light client core

Godeps/_workspace/src/golang.org/x/net/context/context.go

@@ -0,0 +1,447 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package context defines the Context type, which carries deadlines,
+// cancelation signals, and other request-scoped values across API boundaries
+// and between processes.
+//
+// Incoming requests to a server should create a Context, and outgoing calls to
+// servers should accept a Context.  The chain of function calls between must
+// propagate the Context, optionally replacing it with a modified copy created
+// using WithDeadline, WithTimeout, WithCancel, or WithValue.
+//
+// Programs that use Contexts should follow these rules to keep interfaces
+// consistent across packages and enable static analysis tools to check context
+// propagation:
+//
+// Do not store Contexts inside a struct type; instead, pass a Context
+// explicitly to each function that needs it.  The Context should be the first
+// parameter, typically named ctx:
+//
+// 	func DoSomething(ctx context.Context, arg Arg) error {
+// 		// ... use ctx ...
+// 	}
+//
+// Do not pass a nil Context, even if a function permits it.  Pass context.TODO
+// if you are unsure about which Context to use.
+//
+// Use context Values only for request-scoped data that transits processes and
+// APIs, not for passing optional parameters to functions.
+//
+// The same Context may be passed to functions running in different goroutines;
+// Contexts are safe for simultaneous use by multiple goroutines.
+//
+// See http://blog.golang.org/context for example code for a server that uses
+// Contexts.
+package context // import "golang.org/x/net/context"
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+)
+
+// A Context carries a deadline, a cancelation signal, and other values across
+// API boundaries.
+//
+// Context's methods may be called by multiple goroutines simultaneously.
+type Context interface {
+	// Deadline returns the time when work done on behalf of this context
+	// should be canceled.  Deadline returns ok==false when no deadline is
+	// set.  Successive calls to Deadline return the same results.
+	Deadline() (deadline time.Time, ok bool)
+
+	// Done returns a channel that's closed when work done on behalf of this
+	// context should be canceled.  Done may return nil if this context can
+	// never be canceled.  Successive calls to Done return the same value.
+	//
+	// WithCancel arranges for Done to be closed when cancel is called;
+	// WithDeadline arranges for Done to be closed when the deadline
+	// expires; WithTimeout arranges for Done to be closed when the timeout
+	// elapses.
+	//
+	// Done is provided for use in select statements:
+	//
+	//  // Stream generates values with DoSomething and sends them to out
+	//  // until DoSomething returns an error or ctx.Done is closed.
+	//  func Stream(ctx context.Context, out <-chan Value) error {
+	//  	for {
+	//  		v, err := DoSomething(ctx)
+	//  		if err != nil {
+	//  			return err
+	//  		}
+	//  		select {
+	//  		case <-ctx.Done():
+	//  			return ctx.Err()
+	//  		case out <- v:
+	//  		}
+	//  	}
+	//  }
+	//
+	// See http://blog.golang.org/pipelines for more examples of how to use
+	// a Done channel for cancelation.
+	Done() <-chan struct{}
+
+	// Err returns a non-nil error value after Done is closed.  Err returns
+	// Canceled if the context was canceled or DeadlineExceeded if the
+	// context's deadline passed.  No other values for Err are defined.
+	// After Done is closed, successive calls to Err return the same value.
+	Err() error
+
+	// Value returns the value associated with this context for key, or nil
+	// if no value is associated with key.  Successive calls to Value with
+	// the same key returns the same result.
+	//
+	// Use context values only for request-scoped data that transits
+	// processes and API boundaries, not for passing optional parameters to
+	// functions.
+	//
+	// A key identifies a specific value in a Context.  Functions that wish
+	// to store values in Context typically allocate a key in a global
+	// variable then use that key as the argument to context.WithValue and
+	// Context.Value.  A key can be any type that supports equality;
+	// packages should define keys as an unexported type to avoid
+	// collisions.
+	//
+	// Packages that define a Context key should provide type-safe accessors
+	// for the values stores using that key:
+	//
+	// 	// Package user defines a User type that's stored in Contexts.
+	// 	package user
+	//
+	// 	import "golang.org/x/net/context"
+	//
+	// 	// User is the type of value stored in the Contexts.
+	// 	type User struct {...}
+	//
+	// 	// key is an unexported type for keys defined in this package.
+	// 	// This prevents collisions with keys defined in other packages.
+	// 	type key int
+	//
+	// 	// userKey is the key for user.User values in Contexts.  It is
+	// 	// unexported; clients use user.NewContext and user.FromContext
+	// 	// instead of using this key directly.
+	// 	var userKey key = 0
+	//
+	// 	// NewContext returns a new Context that carries value u.
+	// 	func NewContext(ctx context.Context, u *User) context.Context {
+	// 		return context.WithValue(ctx, userKey, u)
+	// 	}
+	//
+	// 	// FromContext returns the User value stored in ctx, if any.
+	// 	func FromContext(ctx context.Context) (*User, bool) {
+	// 		u, ok := ctx.Value(userKey).(*User)
+	// 		return u, ok
+	// 	}
+	Value(key interface{}) interface{}
+}
+
+// Canceled is the error returned by Context.Err when the context is canceled.
+var Canceled = errors.New("context canceled")
+
+// DeadlineExceeded is the error returned by Context.Err when the context's
+// deadline passes.
+var DeadlineExceeded = errors.New("context deadline exceeded")
+
+// An emptyCtx is never canceled, has no values, and has no deadline.  It is not
+// struct{}, since vars of this type must have distinct addresses.
+type emptyCtx int
+
+func (*emptyCtx) Deadline() (deadline time.Time, ok bool) {
+	return
+}
+
+func (*emptyCtx) Done() <-chan struct{} {
+	return nil
+}
+
+func (*emptyCtx) Err() error {
+	return nil
+}
+
+func (*emptyCtx) Value(key interface{}) interface{} {
+	return nil
+}
+
+func (e *emptyCtx) String() string {
+	switch e {
+	case background:
+		return "context.Background"
+	case todo:
+		return "context.TODO"
+	}
+	return "unknown empty Context"
+}
+
+var (
+	background = new(emptyCtx)
+	todo       = new(emptyCtx)
+)
+
+// Background returns a non-nil, empty Context. It is never canceled, has no
+// values, and has no deadline.  It is typically used by the main function,
+// initialization, and tests, and as the top-level Context for incoming
+// requests.
+func Background() Context {
+	return background
+}
+
+// TODO returns a non-nil, empty Context.  Code should use context.TODO when
+// it's unclear which Context to use or it's is not yet available (because the
+// surrounding function has not yet been extended to accept a Context
+// parameter).  TODO is recognized by static analysis tools that determine
+// whether Contexts are propagated correctly in a program.
+func TODO() Context {
+	return todo
+}
+
+// A CancelFunc tells an operation to abandon its work.
+// A CancelFunc does not wait for the work to stop.
+// After the first call, subsequent calls to a CancelFunc do nothing.
+type CancelFunc func()
+
+// WithCancel returns a copy of parent with a new Done channel. The returned
+// context's Done channel is closed when the returned cancel function is called
+// or when the parent context's Done channel is closed, whichever happens first.
+//
+// Canceling this context releases resources associated with it, so code should
+// call cancel as soon as the operations running in this Context complete.
+func WithCancel(parent Context) (ctx Context, cancel CancelFunc) {
+	c := newCancelCtx(parent)
+	propagateCancel(parent, &c)
+	return &c, func() { c.cancel(true, Canceled) }
+}
+
+// newCancelCtx returns an initialized cancelCtx.
+func newCancelCtx(parent Context) cancelCtx {
+	return cancelCtx{
+		Context: parent,
+		done:    make(chan struct{}),
+	}
+}
+
+// propagateCancel arranges for child to be canceled when parent is.
+func propagateCancel(parent Context, child canceler) {
+	if parent.Done() == nil {
+		return // parent is never canceled
+	}
+	if p, ok := parentCancelCtx(parent); ok {
+		p.mu.Lock()
+		if p.err != nil {
+			// parent has already been canceled
+			child.cancel(false, p.err)
+		} else {
+			if p.children == nil {
+				p.children = make(map[canceler]bool)
+			}
+			p.children[child] = true
+		}
+		p.mu.Unlock()
+	} else {
+		go func() {
+			select {
+			case <-parent.Done():
+				child.cancel(false, parent.Err())
+			case <-child.Done():
+			}
+		}()
+	}
+}
+
+// parentCancelCtx follows a chain of parent references until it finds a
+// *cancelCtx.  This function understands how each of the concrete types in this
+// package represents its parent.
+func parentCancelCtx(parent Context) (*cancelCtx, bool) {
+	for {
+		switch c := parent.(type) {
+		case *cancelCtx:
+			return c, true
+		case *timerCtx:
+			return &c.cancelCtx, true
+		case *valueCtx:
+			parent = c.Context
+		default:
+			return nil, false
+		}
+	}
+}
+
+// removeChild removes a context from its parent.
+func removeChild(parent Context, child canceler) {
+	p, ok := parentCancelCtx(parent)
+	if !ok {
+		return
+	}
+	p.mu.Lock()
+	if p.children != nil {
+		delete(p.children, child)
+	}
+	p.mu.Unlock()
+}
+
+// A canceler is a context type that can be canceled directly.  The
+// implementations are *cancelCtx and *timerCtx.
+type canceler interface {
+	cancel(removeFromParent bool, err error)
+	Done() <-chan struct{}
+}
+
+// A cancelCtx can be canceled.  When canceled, it also cancels any children
+// that implement canceler.
+type cancelCtx struct {
+	Context
+
+	done chan struct{} // closed by the first cancel call.
+
+	mu       sync.Mutex
+	children map[canceler]bool // set to nil by the first cancel call
+	err      error             // set to non-nil by the first cancel call
+}
+
+func (c *cancelCtx) Done() <-chan struct{} {
+	return c.done
+}
+
+func (c *cancelCtx) Err() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.err
+}
+
+func (c *cancelCtx) String() string {
+	return fmt.Sprintf("%v.WithCancel", c.Context)
+}
+
+// cancel closes c.done, cancels each of c's children, and, if
+// removeFromParent is true, removes c from its parent's children.
+func (c *cancelCtx) cancel(removeFromParent bool, err error) {
+	if err == nil {
+		panic("context: internal error: missing cancel error")
+	}
+	c.mu.Lock()
+	if c.err != nil {
+		c.mu.Unlock()
+		return // already canceled
+	}
+	c.err = err
+	close(c.done)
+	for child := range c.children {
+		// NOTE: acquiring the child's lock while holding parent's lock.
+		child.cancel(false, err)
+	}
+	c.children = nil
+	c.mu.Unlock()
+
+	if removeFromParent {
+		removeChild(c.Context, c)
+	}
+}
+
+// WithDeadline returns a copy of the parent context with the deadline adjusted
+// to be no later than d.  If the parent's deadline is already earlier than d,
+// WithDeadline(parent, d) is semantically equivalent to parent.  The returned
+// context's Done channel is closed when the deadline expires, when the returned
+// cancel function is called, or when the parent context's Done channel is
+// closed, whichever happens first.
+//
+// Canceling this context releases resources associated with it, so code should
+// call cancel as soon as the operations running in this Context complete.
+func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
+	if cur, ok := parent.Deadline(); ok && cur.Before(deadline) {
+		// The current deadline is already sooner than the new one.
+		return WithCancel(parent)
+	}
+	c := &timerCtx{
+		cancelCtx: newCancelCtx(parent),
+		deadline:  deadline,
+	}
+	propagateCancel(parent, c)
+	d := deadline.Sub(time.Now())
+	if d <= 0 {
+		c.cancel(true, DeadlineExceeded) // deadline has already passed
+		return c, func() { c.cancel(true, Canceled) }
+	}
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.err == nil {
+		c.timer = time.AfterFunc(d, func() {
+			c.cancel(true, DeadlineExceeded)
+		})
+	}
+	return c, func() { c.cancel(true, Canceled) }
+}
+
+// A timerCtx carries a timer and a deadline.  It embeds a cancelCtx to
+// implement Done and Err.  It implements cancel by stopping its timer then
+// delegating to cancelCtx.cancel.
+type timerCtx struct {
+	cancelCtx
+	timer *time.Timer // Under cancelCtx.mu.
+
+	deadline time.Time
+}
+
+func (c *timerCtx) Deadline() (deadline time.Time, ok bool) {
+	return c.deadline, true
+}
+
+func (c *timerCtx) String() string {
+	return fmt.Sprintf("%v.WithDeadline(%s [%s])", c.cancelCtx.Context, c.deadline, c.deadline.Sub(time.Now()))
+}
+
+func (c *timerCtx) cancel(removeFromParent bool, err error) {
+	c.cancelCtx.cancel(false, err)
+	if removeFromParent {
+		// Remove this timerCtx from its parent cancelCtx's children.
+		removeChild(c.cancelCtx.Context, c)
+	}
+	c.mu.Lock()
+	if c.timer != nil {
+		c.timer.Stop()
+		c.timer = nil
+	}
+	c.mu.Unlock()
+}
+
+// WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).
+//
+// Canceling this context releases resources associated with it, so code should
+// call cancel as soon as the operations running in this Context complete:
+//
+// 	func slowOperationWithTimeout(ctx context.Context) (Result, error) {
+// 		ctx, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
+// 		defer cancel()  // releases resources if slowOperation completes before timeout elapses
+// 		return slowOperation(ctx)
+// 	}
+func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) {
+	return WithDeadline(parent, time.Now().Add(timeout))
+}
+
+// WithValue returns a copy of parent in which the value associated with key is
+// val.
+//
+// Use context Values only for request-scoped data that transits processes and
+// APIs, not for passing optional parameters to functions.
+func WithValue(parent Context, key interface{}, val interface{}) Context {
+	return &valueCtx{parent, key, val}
+}
+
+// A valueCtx carries a key-value pair.  It implements Value for that key and
+// delegates all other calls to the embedded Context.
+type valueCtx struct {
+	Context
+	key, val interface{}
+}
+
+func (c *valueCtx) String() string {
+	return fmt.Sprintf("%v.WithValue(%#v, %#v)", c.Context, c.key, c.val)
+}
+
+func (c *valueCtx) Value(key interface{}) interface{} {
+	if c.key == key {
+		return c.val
+	}
+	return c.Context.Value(key)
+}

Godeps/_workspace/src/golang.org/x/net/context/context_test.go

@@ -0,0 +1,575 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package context
+
+import (
+	"fmt"
+	"math/rand"
+	"runtime"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+)
+
+// otherContext is a Context that's not one of the types defined in context.go.
+// This lets us test code paths that differ based on the underlying type of the
+// Context.
+type otherContext struct {
+	Context
+}
+
+func TestBackground(t *testing.T) {
+	c := Background()
+	if c == nil {
+		t.Fatalf("Background returned nil")
+	}
+	select {
+	case x := <-c.Done():
+		t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
+	default:
+	}
+	if got, want := fmt.Sprint(c), "context.Background"; got != want {
+		t.Errorf("Background().String() = %q want %q", got, want)
+	}
+}
+
+func TestTODO(t *testing.T) {
+	c := TODO()
+	if c == nil {
+		t.Fatalf("TODO returned nil")
+	}
+	select {
+	case x := <-c.Done():
+		t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
+	default:
+	}
+	if got, want := fmt.Sprint(c), "context.TODO"; got != want {
+		t.Errorf("TODO().String() = %q want %q", got, want)
+	}
+}
+
+func TestWithCancel(t *testing.T) {
+	c1, cancel := WithCancel(Background())
+
+	if got, want := fmt.Sprint(c1), "context.Background.WithCancel"; got != want {
+		t.Errorf("c1.String() = %q want %q", got, want)
+	}
+
+	o := otherContext{c1}
+	c2, _ := WithCancel(o)
+	contexts := []Context{c1, o, c2}
+
+	for i, c := range contexts {
+		if d := c.Done(); d == nil {
+			t.Errorf("c[%d].Done() == %v want non-nil", i, d)
+		}
+		if e := c.Err(); e != nil {
+			t.Errorf("c[%d].Err() == %v want nil", i, e)
+		}
+
+		select {
+		case x := <-c.Done():
+			t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+	}
+
+	cancel()
+	time.Sleep(100 * time.Millisecond) // let cancelation propagate
+
+	for i, c := range contexts {
+		select {
+		case <-c.Done():
+		default:
+			t.Errorf("<-c[%d].Done() blocked, but shouldn't have", i)
+		}
+		if e := c.Err(); e != Canceled {
+			t.Errorf("c[%d].Err() == %v want %v", i, e, Canceled)
+		}
+	}
+}
+
+func TestParentFinishesChild(t *testing.T) {
+	// Context tree:
+	// parent -> cancelChild
+	// parent -> valueChild -> timerChild
+	parent, cancel := WithCancel(Background())
+	cancelChild, stop := WithCancel(parent)
+	defer stop()
+	valueChild := WithValue(parent, "key", "value")
+	timerChild, stop := WithTimeout(valueChild, 10000*time.Hour)
+	defer stop()
+
+	select {
+	case x := <-parent.Done():
+		t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+	case x := <-cancelChild.Done():
+		t.Errorf("<-cancelChild.Done() == %v want nothing (it should block)", x)
+	case x := <-timerChild.Done():
+		t.Errorf("<-timerChild.Done() == %v want nothing (it should block)", x)
+	case x := <-valueChild.Done():
+		t.Errorf("<-valueChild.Done() == %v want nothing (it should block)", x)
+	default:
+	}
+
+	// The parent's children should contain the two cancelable children.
+	pc := parent.(*cancelCtx)
+	cc := cancelChild.(*cancelCtx)
+	tc := timerChild.(*timerCtx)
+	pc.mu.Lock()
+	if len(pc.children) != 2 || !pc.children[cc] || !pc.children[tc] {
+		t.Errorf("bad linkage: pc.children = %v, want %v and %v",
+			pc.children, cc, tc)
+	}
+	pc.mu.Unlock()
+
+	if p, ok := parentCancelCtx(cc.Context); !ok || p != pc {
+		t.Errorf("bad linkage: parentCancelCtx(cancelChild.Context) = %v, %v want %v, true", p, ok, pc)
+	}
+	if p, ok := parentCancelCtx(tc.Context); !ok || p != pc {
+		t.Errorf("bad linkage: parentCancelCtx(timerChild.Context) = %v, %v want %v, true", p, ok, pc)
+	}
+
+	cancel()
+
+	pc.mu.Lock()
+	if len(pc.children) != 0 {
+		t.Errorf("pc.cancel didn't clear pc.children = %v", pc.children)
+	}
+	pc.mu.Unlock()
+
+	// parent and children should all be finished.
+	check := func(ctx Context, name string) {
+		select {
+		case <-ctx.Done():
+		default:
+			t.Errorf("<-%s.Done() blocked, but shouldn't have", name)
+		}
+		if e := ctx.Err(); e != Canceled {
+			t.Errorf("%s.Err() == %v want %v", name, e, Canceled)
+		}
+	}
+	check(parent, "parent")
+	check(cancelChild, "cancelChild")
+	check(valueChild, "valueChild")
+	check(timerChild, "timerChild")
+
+	// WithCancel should return a canceled context on a canceled parent.
+	precanceledChild := WithValue(parent, "key", "value")
+	select {
+	case <-precanceledChild.Done():
+	default:
+		t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
+	}
+	if e := precanceledChild.Err(); e != Canceled {
+		t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
+	}
+}
+
+func TestChildFinishesFirst(t *testing.T) {
+	cancelable, stop := WithCancel(Background())
+	defer stop()
+	for _, parent := range []Context{Background(), cancelable} {
+		child, cancel := WithCancel(parent)
+
+		select {
+		case x := <-parent.Done():
+			t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+		case x := <-child.Done():
+			t.Errorf("<-child.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+
+		cc := child.(*cancelCtx)
+		pc, pcok := parent.(*cancelCtx) // pcok == false when parent == Background()
+		if p, ok := parentCancelCtx(cc.Context); ok != pcok || (ok && pc != p) {
+			t.Errorf("bad linkage: parentCancelCtx(cc.Context) = %v, %v want %v, %v", p, ok, pc, pcok)
+		}
+
+		if pcok {
+			pc.mu.Lock()
+			if len(pc.children) != 1 || !pc.children[cc] {
+				t.Errorf("bad linkage: pc.children = %v, cc = %v", pc.children, cc)
+			}
+			pc.mu.Unlock()
+		}
+
+		cancel()
+
+		if pcok {
+			pc.mu.Lock()
+			if len(pc.children) != 0 {
+				t.Errorf("child's cancel didn't remove self from pc.children = %v", pc.children)
+			}
+			pc.mu.Unlock()
+		}
+
+		// child should be finished.
+		select {
+		case <-child.Done():
+		default:
+			t.Errorf("<-child.Done() blocked, but shouldn't have")
+		}
+		if e := child.Err(); e != Canceled {
+			t.Errorf("child.Err() == %v want %v", e, Canceled)
+		}
+
+		// parent should not be finished.
+		select {
+		case x := <-parent.Done():
+			t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+		if e := parent.Err(); e != nil {
+			t.Errorf("parent.Err() == %v want nil", e)
+		}
+	}
+}
+
+func testDeadline(c Context, wait time.Duration, t *testing.T) {
+	select {
+	case <-time.After(wait):
+		t.Fatalf("context should have timed out")
+	case <-c.Done():
+	}
+	if e := c.Err(); e != DeadlineExceeded {
+		t.Errorf("c.Err() == %v want %v", e, DeadlineExceeded)
+	}
+}
+
+func TestDeadline(t *testing.T) {
+	c, _ := WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
+	if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
+		t.Errorf("c.String() = %q want prefix %q", got, prefix)
+	}
+	testDeadline(c, 200*time.Millisecond, t)
+
+	c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
+	o := otherContext{c}
+	testDeadline(o, 200*time.Millisecond, t)
+
+	c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
+	o = otherContext{c}
+	c, _ = WithDeadline(o, time.Now().Add(300*time.Millisecond))
+	testDeadline(c, 200*time.Millisecond, t)
+}
+
+func TestTimeout(t *testing.T) {
+	c, _ := WithTimeout(Background(), 100*time.Millisecond)
+	if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
+		t.Errorf("c.String() = %q want prefix %q", got, prefix)
+	}
+	testDeadline(c, 200*time.Millisecond, t)
+
+	c, _ = WithTimeout(Background(), 100*time.Millisecond)
+	o := otherContext{c}
+	testDeadline(o, 200*time.Millisecond, t)
+
+	c, _ = WithTimeout(Background(), 100*time.Millisecond)
+	o = otherContext{c}
+	c, _ = WithTimeout(o, 300*time.Millisecond)
+	testDeadline(c, 200*time.Millisecond, t)
+}
+
+func TestCanceledTimeout(t *testing.T) {
+	c, _ := WithTimeout(Background(), 200*time.Millisecond)
+	o := otherContext{c}
+	c, cancel := WithTimeout(o, 400*time.Millisecond)
+	cancel()
+	time.Sleep(100 * time.Millisecond) // let cancelation propagate
+	select {
+	case <-c.Done():
+	default:
+		t.Errorf("<-c.Done() blocked, but shouldn't have")
+	}
+	if e := c.Err(); e != Canceled {
+		t.Errorf("c.Err() == %v want %v", e, Canceled)
+	}
+}
+
+type key1 int
+type key2 int
+
+var k1 = key1(1)
+var k2 = key2(1) // same int as k1, different type
+var k3 = key2(3) // same type as k2, different int
+
+func TestValues(t *testing.T) {
+	check := func(c Context, nm, v1, v2, v3 string) {
+		if v, ok := c.Value(k1).(string); ok == (len(v1) == 0) || v != v1 {
+			t.Errorf(`%s.Value(k1).(string) = %q, %t want %q, %t`, nm, v, ok, v1, len(v1) != 0)
+		}
+		if v, ok := c.Value(k2).(string); ok == (len(v2) == 0) || v != v2 {
+			t.Errorf(`%s.Value(k2).(string) = %q, %t want %q, %t`, nm, v, ok, v2, len(v2) != 0)
+		}
+		if v, ok := c.Value(k3).(string); ok == (len(v3) == 0) || v != v3 {
+			t.Errorf(`%s.Value(k3).(string) = %q, %t want %q, %t`, nm, v, ok, v3, len(v3) != 0)
+		}
+	}
+
+	c0 := Background()
+	check(c0, "c0", "", "", "")
+
+	c1 := WithValue(Background(), k1, "c1k1")
+	check(c1, "c1", "c1k1", "", "")
+
+	if got, want := fmt.Sprint(c1), `context.Background.WithValue(1, "c1k1")`; got != want {
+		t.Errorf("c.String() = %q want %q", got, want)
+	}
+
+	c2 := WithValue(c1, k2, "c2k2")
+	check(c2, "c2", "c1k1", "c2k2", "")
+
+	c3 := WithValue(c2, k3, "c3k3")
+	check(c3, "c2", "c1k1", "c2k2", "c3k3")
+
+	c4 := WithValue(c3, k1, nil)
+	check(c4, "c4", "", "c2k2", "c3k3")
+
+	o0 := otherContext{Background()}
+	check(o0, "o0", "", "", "")
+
+	o1 := otherContext{WithValue(Background(), k1, "c1k1")}
+	check(o1, "o1", "c1k1", "", "")
+
+	o2 := WithValue(o1, k2, "o2k2")
+	check(o2, "o2", "c1k1", "o2k2", "")
+
+	o3 := otherContext{c4}
+	check(o3, "o3", "", "c2k2", "c3k3")
+
+	o4 := WithValue(o3, k3, nil)
+	check(o4, "o4", "", "c2k2", "")
+}
+
+func TestAllocs(t *testing.T) {
+	bg := Background()
+	for _, test := range []struct {
+		desc       string
+		f          func()
+		limit      float64
+		gccgoLimit float64
+	}{
+		{
+			desc:       "Background()",
+			f:          func() { Background() },
+			limit:      0,
+			gccgoLimit: 0,
+		},
+		{
+			desc: fmt.Sprintf("WithValue(bg, %v, nil)", k1),
+			f: func() {
+				c := WithValue(bg, k1, nil)
+				c.Value(k1)
+			},
+			limit:      3,
+			gccgoLimit: 3,
+		},
+		{
+			desc: "WithTimeout(bg, 15*time.Millisecond)",
+			f: func() {
+				c, _ := WithTimeout(bg, 15*time.Millisecond)
+				<-c.Done()
+			},
+			limit:      8,
+			gccgoLimit: 13,
+		},
+		{
+			desc: "WithCancel(bg)",
+			f: func() {
+				c, cancel := WithCancel(bg)
+				cancel()
+				<-c.Done()
+			},
+			limit:      5,
+			gccgoLimit: 8,
+		},
+		{
+			desc: "WithTimeout(bg, 100*time.Millisecond)",
+			f: func() {
+				c, cancel := WithTimeout(bg, 100*time.Millisecond)
+				cancel()
+				<-c.Done()
+			},
+			limit:      8,
+			gccgoLimit: 25,
+		},
+	} {
+		limit := test.limit
+		if runtime.Compiler == "gccgo" {
+			// gccgo does not yet do escape analysis.
+			// TOOD(iant): Remove this when gccgo does do escape analysis.
+			limit = test.gccgoLimit
+		}
+		if n := testing.AllocsPerRun(100, test.f); n > limit {
+			t.Errorf("%s allocs = %f want %d", test.desc, n, int(limit))
+		}
+	}
+}
+
+func TestSimultaneousCancels(t *testing.T) {
+	root, cancel := WithCancel(Background())
+	m := map[Context]CancelFunc{root: cancel}
+	q := []Context{root}
+	// Create a tree of contexts.
+	for len(q) != 0 && len(m) < 100 {
+		parent := q[0]
+		q = q[1:]
+		for i := 0; i < 4; i++ {
+			ctx, cancel := WithCancel(parent)
+			m[ctx] = cancel
+			q = append(q, ctx)
+		}
+	}
+	// Start all the cancels in a random order.
+	var wg sync.WaitGroup
+	wg.Add(len(m))
+	for _, cancel := range m {
+		go func(cancel CancelFunc) {
+			cancel()
+			wg.Done()
+		}(cancel)
+	}
+	// Wait on all the contexts in a random order.
+	for ctx := range m {
+		select {
+		case <-ctx.Done():
+		case <-time.After(1 * time.Second):
+			buf := make([]byte, 10<<10)
+			n := runtime.Stack(buf, true)
+			t.Fatalf("timed out waiting for <-ctx.Done(); stacks:\n%s", buf[:n])
+		}
+	}
+	// Wait for all the cancel functions to return.
+	done := make(chan struct{})
+	go func() {
+		wg.Wait()
+		close(done)
+	}()
+	select {
+	case <-done:
+	case <-time.After(1 * time.Second):
+		buf := make([]byte, 10<<10)
+		n := runtime.Stack(buf, true)
+		t.Fatalf("timed out waiting for cancel functions; stacks:\n%s", buf[:n])
+	}
+}
+
+func TestInterlockedCancels(t *testing.T) {
+	parent, cancelParent := WithCancel(Background())
+	child, cancelChild := WithCancel(parent)
+	go func() {
+		parent.Done()
+		cancelChild()
+	}()
+	cancelParent()
+	select {
+	case <-child.Done():
+	case <-time.After(1 * time.Second):
+		buf := make([]byte, 10<<10)
+		n := runtime.Stack(buf, true)
+		t.Fatalf("timed out waiting for child.Done(); stacks:\n%s", buf[:n])
+	}
+}
+
+func TestLayersCancel(t *testing.T) {
+	testLayers(t, time.Now().UnixNano(), false)
+}
+
+func TestLayersTimeout(t *testing.T) {
+	testLayers(t, time.Now().UnixNano(), true)
+}
+
+func testLayers(t *testing.T, seed int64, testTimeout bool) {
+	rand.Seed(seed)
+	errorf := func(format string, a ...interface{}) {
+		t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
+	}
+	const (
+		timeout   = 200 * time.Millisecond
+		minLayers = 30
+	)
+	type value int
+	var (
+		vals      []*value
+		cancels   []CancelFunc
+		numTimers int
+		ctx       = Background()
+	)
+	for i := 0; i < minLayers || numTimers == 0 || len(cancels) == 0 || len(vals) == 0; i++ {
+		switch rand.Intn(3) {
+		case 0:
+			v := new(value)
+			ctx = WithValue(ctx, v, v)
+			vals = append(vals, v)
+		case 1:
+			var cancel CancelFunc
+			ctx, cancel = WithCancel(ctx)
+			cancels = append(cancels, cancel)
+		case 2:
+			var cancel CancelFunc
+			ctx, cancel = WithTimeout(ctx, timeout)
+			cancels = append(cancels, cancel)
+			numTimers++
+		}
+	}
+	checkValues := func(when string) {
+		for _, key := range vals {
+			if val := ctx.Value(key).(*value); key != val {
+				errorf("%s: ctx.Value(%p) = %p want %p", when, key, val, key)
+			}
+		}
+	}
+	select {
+	case <-ctx.Done():
+		errorf("ctx should not be canceled yet")
+	default:
+	}
+	if s, prefix := fmt.Sprint(ctx), "context.Background."; !strings.HasPrefix(s, prefix) {
+		t.Errorf("ctx.String() = %q want prefix %q", s, prefix)
+	}
+	t.Log(ctx)
+	checkValues("before cancel")
+	if testTimeout {
+		select {
+		case <-ctx.Done():
+		case <-time.After(timeout + timeout/10):
+			errorf("ctx should have timed out")
+		}
+		checkValues("after timeout")
+	} else {
+		cancel := cancels[rand.Intn(len(cancels))]
+		cancel()
+		select {
+		case <-ctx.Done():
+		default:
+			errorf("ctx should be canceled")
+		}
+		checkValues("after cancel")
+	}
+}
+
+func TestCancelRemoves(t *testing.T) {
+	checkChildren := func(when string, ctx Context, want int) {
+		if got := len(ctx.(*cancelCtx).children); got != want {
+			t.Errorf("%s: context has %d children, want %d", when, got, want)
+		}
+	}
+
+	ctx, _ := WithCancel(Background())
+	checkChildren("after creation", ctx, 0)
+	_, cancel := WithCancel(ctx)
+	checkChildren("with WithCancel child ", ctx, 1)
+	cancel()
+	checkChildren("after cancelling WithCancel child", ctx, 0)
+
+	ctx, _ = WithCancel(Background())
+	checkChildren("after creation", ctx, 0)
+	_, cancel = WithTimeout(ctx, 60*time.Minute)
+	checkChildren("with WithTimeout child ", ctx, 1)
+	cancel()
+	checkChildren("after cancelling WithTimeout child", ctx, 0)
+}

Godeps/_workspace/src/golang.org/x/net/context/withtimeout_test.go

@@ -0,0 +1,26 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package context_test
+
+import (
+	"fmt"
+	"time"
+
+	"golang.org/x/net/context"
+)
+
+func ExampleWithTimeout() {
+	// Pass a context with a timeout to tell a blocking function that it
+	// should abandon its work after the timeout elapses.
+	ctx, _ := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	select {
+	case <-time.After(200 * time.Millisecond):
+		fmt.Println("overslept")
+	case <-ctx.Done():
+		fmt.Println(ctx.Err()) // prints "context deadline exceeded"
+	}
+	// Output:
+	// context deadline exceeded
+}

cmd/evm/main.go

@@ -28,6 +28,7 @@ import (
 	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -113,7 +114,7 @@ func run(ctx *cli.Context) {
 	glog.SetV(ctx.GlobalInt(VerbosityFlag.Name))
 
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
+	statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 	sender := statedb.CreateAccount(common.StringToAddress("sender"))
 	receiver := statedb.CreateAccount(common.StringToAddress("receiver"))
 	receiver.SetCode(common.Hex2Bytes(ctx.GlobalString(CodeFlag.Name)))

cmd/geth/chaincmd.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -179,7 +180,7 @@ func dump(ctx *cli.Context) {
 			fmt.Println("{}")
 			utils.Fatalf("block not found")
 		} else {
-			state, err := state.New(block.Root(), chainDb)
+			state, err := state.New(block.Root(), access.NewDbChainAccess(chainDb))
 			if err != nil {
 				utils.Fatalf("could not create new state: %v", err)
 				return

cmd/geth/main.go

@@ -34,6 +34,7 @@ import (
 	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -555,12 +556,13 @@ func blockRecovery(ctx *cli.Context) {
 	if err != nil {
 		glog.Fatalln("could not open db:", err)
 	}
+	ca := access.NewDbChainAccess(blockDb)
 
 	var block *types.Block
 	if arg[0] == '#' {
-		block = core.GetBlock(blockDb, core.GetCanonicalHash(blockDb, common.String2Big(arg[1:]).Uint64()))
+		block = core.GetBlock(ca, core.GetCanonicalHash(blockDb, common.String2Big(arg[1:]).Uint64()))
 	} else {
-		block = core.GetBlock(blockDb, common.HexToHash(arg))
+		block = core.GetBlock(ca, common.HexToHash(arg))
 	}
 
 	if block == nil {

cmd/utils/flags.go

@@ -34,6 +34,7 @@ import (
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/eth"
@@ -552,12 +553,12 @@ func MakeChain(ctx *cli.Context) (chain *core.BlockChain, chainDb ethdb.Database
 	eventMux := new(event.TypeMux)
 	pow := ethash.New()
 	//genesis := core.GenesisBlock(uint64(ctx.GlobalInt(GenesisNonceFlag.Name)), blockDB)
-	chain, err = core.NewBlockChain(chainDb, pow, eventMux)
+	chain, err = core.NewBlockChain(access.NewDbChainAccess(chainDb), pow, eventMux)
 	if err != nil {
 		Fatalf("Could not start chainmanager: %v", err)
 	}
 
-	proc := core.NewBlockProcessor(chainDb, pow, chain, eventMux)
+	proc := core.NewBlockProcessor(access.NewDbChainAccess(chainDb), pow, chain, eventMux)
 	chain.SetProcessor(proc)
 	return chain, chainDb
 }

core/access/chain_access.go

@@ -0,0 +1,219 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package access provides a layer to handle local blockchain database and
+// on-demand network retrieval
+package access
+
+import (
+	"errors"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"golang.org/x/net/context"
+)
+
+var (
+	errNotInDb = errors.New("object not found in database")
+)
+
+const LogLevel = logger.Debug
+
+var (
+	requestTimeout = time.Millisecond * 300
+	retryPeers     = time.Second * 1
+)
+
+// ChainAccess provides access to blockchain and state data through local
+// database and optionally also on-demand network retrieval
+type ChainAccess struct {
+	db         ethdb.Database
+	odr        bool // light client mode, odr enabled
+	lock       sync.Mutex
+	sentReqs   map[uint64]*sentReq
+	sentReqCnt uint64
+	peers      *peerSet
+}
+
+// requestFunc is a function that requests some data from a peer
+type requestFunc func(*Peer) error
+
+// validatorFunc is a function that processes a message and returns true if
+// it was a meaningful answer to a given request
+type validatorFunc func(*Msg) bool
+
+// sentReq is a request waiting for an answer that satisfies its valFunc
+type sentReq struct {
+	valFunc     validatorFunc
+	deliverChan chan *Msg
+}
+
+// NewDbChainAccess creates a ChainAccess with ODR disabled
+func NewDbChainAccess(db ethdb.Database) *ChainAccess {
+	return NewChainAccess(db, false)
+}
+
+// NewChainAccess create a ChainAccess with optional ODR
+func NewChainAccess(db ethdb.Database, odr bool) *ChainAccess {
+	return &ChainAccess{
+		db:       db,
+		peers:    newPeerSet(),
+		sentReqs: make(map[uint64]*sentReq),
+		odr:      odr,
+	}
+}
+
+// Db returns the local database assigned to the ChainAccess object
+func (self *ChainAccess) Db() ethdb.Database {
+	return self.db
+}
+
+// OdrEnabled returns true if this ChainAccess is capable of doing ODR requests
+func (self *ChainAccess) OdrEnabled() bool {
+	return self.odr
+}
+
+// RegisterPeer registers a new LES peer to the ODR capable peer set
+func (self *ChainAccess) RegisterPeer(id string, version int, head common.Hash, getBlockBodies getBlockBodiesFn, getNodeData getNodeDataFn, getReceipts getReceiptsFn, getProofs getProofsFn) error {
+	glog.V(logger.Detail).Infoln("Registering peer", id)
+	if err := self.peers.Register(newPeer(id, version, head, getBlockBodies, getNodeData, getReceipts, getProofs)); err != nil {
+		glog.V(logger.Error).Infoln("Register failed:", err)
+		return err
+	}
+	return nil
+}
+
+// UnregisterPeer removes a peer from the ODR capable peer set
+func (self *ChainAccess) UnregisterPeer(id string) {
+	self.peers.Unregister(id)
+}
+
+const (
+	MsgBlockBodies = iota
+	MsgNodeData
+	MsgReceipts
+	MsgProofs
+)
+
+// Msg encodes a LES message that delivers reply data for a request
+type Msg struct {
+	MsgType int
+	Obj     interface{}
+}
+
+// ObjectAccess is the ODR request interface (passed to Retrieve, functions called by Retrieve and Deliver)
+// 		DbGet() tries to retrieve the object from the local database (object is stored by the request struct in memory if retrieved)
+//		DbPut() stores it in the local database
+//		Request(*Peer) requests it from a LES peer
+//		Valid(*Msg) checks if a message is a valid answer to this request and stores the retrieved object in memory
+type ObjectAccess interface {
+	// database storage
+	DbGet() bool
+	DbPut()
+	// network retrieval
+	Request(*Peer) error
+	Valid(*Msg) bool // if true, keeps the retrieved object
+}
+
+// Deliver is called by the LES protocol manager to deliver ODR reply messages to waiting requests
+func (self *ChainAccess) Deliver(id string, msg *Msg) (processed bool) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
+	for i, req := range self.sentReqs {
+		if req.valFunc(msg) {
+			req.deliverChan <- msg
+			delete(self.sentReqs, i)
+			return true
+		}
+	}
+	return false
+}
+
+// networkRequest sends a request to known peers until an answer is received
+// or the context is cancelled
+func (self *ChainAccess) networkRequest(ctx context.Context, rqFunc requestFunc, valFunc validatorFunc) (*Msg, error) {
+	req := &sentReq{
+		deliverChan: make(chan *Msg),
+		valFunc:     valFunc,
+	}
+	self.lock.Lock()
+	reqCnt := self.sentReqCnt
+	self.sentReqCnt++
+	self.sentReqs[reqCnt] = req
+	self.lock.Unlock()
+
+	defer func() {
+		self.lock.Lock()
+		delete(self.sentReqs, reqCnt)
+		self.lock.Unlock()
+	}()
+
+	var msg *Msg
+
+	for {
+		peers := self.peers.BestPeers()
+		if len(peers) == 0 {
+			select {
+			case <-ctx.Done():
+				setTerminated(ctx)
+				return nil, ctx.Err()
+			case <-time.After(retryPeers):
+			}
+		}
+		for _, peer := range peers {
+			rqFunc(peer)
+			select {
+			case <-ctx.Done():
+				setTerminated(ctx)
+				return nil, ctx.Err()
+			case msg = <-req.deliverChan:
+				peer.Promote()
+				glog.V(LogLevel).Infof("networkRequest success")
+				return msg, nil
+			case <-time.After(requestTimeout):
+				peer.Demote()
+				glog.V(LogLevel).Infof("networkRequest timeout")
+			}
+		}
+	}
+}
+
+// Retrieve tries to fetch an object from the local db, then from the LES network.
+// If the network retrieval was successful, it stores the object in local db.
+func (self *ChainAccess) Retrieve(ctx context.Context, obj ObjectAccess) (err error) {
+	// look in db
+	if obj.DbGet() {
+		return nil
+	}
+	if IsOdrContext(ctx) {
+		// not found in db, trying the network
+		_, err = self.networkRequest(ctx, obj.Request, obj.Valid)
+		if err == nil {
+			// retrieved from network, store in db
+			obj.DbPut()
+		} else {
+			glog.V(LogLevel).Infof("networkRequest  err = %v", err)
+		}
+		return
+	} else {
+		return errNotInDb
+	}
+}

core/access/context.go

@@ -0,0 +1,76 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package access provides a layer to handle local blockchain database and
+// on-demand network retrieval
+package access
+
+import (
+	"sync/atomic"
+	"time"
+
+	"golang.org/x/net/context"
+)
+
+// NoOdr is the default context when ODR is not used
+var NoOdr = context.Background()
+
+// NewContext creates an ODR context, carrying channel ID and a "terminated" flag
+func NewContext(id *OdrChannelID) (context.Context, context.CancelFunc) {
+	ctx := context.Background()
+	ctx = context.WithValue(ctx, 0, id)
+	ctx = context.WithValue(ctx, 1, new(int32))
+	return context.WithTimeout(ctx, id.timeout)
+}
+
+// IsOdrContext returns true if ctx is an ODR-enabled context
+func IsOdrContext(ctx context.Context) bool {
+	_, ok := ctx.Value(0).(*OdrChannelID)
+	return ok
+}
+
+// setTerminated switches the "terminated" flag on, notifying caller that any
+// result it received should be considered invalid
+func setTerminated(ctx context.Context) {
+	ptr, ok := ctx.Value(1).(*int32)
+	if ok {
+		atomic.StoreInt32(ptr, 1)
+	}
+}
+
+// Terminated returns true if the "terminated" flag was switched on, meaning
+// that any result received should be considered invalid
+func Terminated(ctx context.Context) bool {
+	ptr, ok := ctx.Value(1).(*int32)
+	if ok {
+		return atomic.LoadInt32(ptr) == 1
+	} else {
+		return false
+	}
+}
+
+// OdrChannelID is a permanent identifier of a source from where
+// requests can come (like an RPC channel).
+// (needed for future functions like "list of my waiting requests" and
+// "cancel all requests from this channel")
+type OdrChannelID struct {
+	timeout time.Duration
+}
+
+// NewChannelID creates a new OdrChannelID with a channel-specific timeout parameter
+func NewChannelID(timeout time.Duration) *OdrChannelID {
+	return &OdrChannelID{timeout: timeout}
+}

core/access/peer.go

@@ -0,0 +1,181 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package access provides a layer to handle local blockchain database and
+// on-demand network retrieval
+package access
+
+import (
+	"errors"
+	"sync"
+	"sync/atomic"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+var (
+	errAlreadyRegistered = errors.New("peer is already registered")
+	errNotRegistered     = errors.New("peer is not registered")
+	errNoOdr             = errors.New("peer cannot serve on-demand requests")
+)
+
+type ProofReq struct {
+	Root common.Hash
+	Key  []byte
+}
+
+type getBlockBodiesFn func([]common.Hash) error
+type getNodeDataFn func([]common.Hash) error
+type getReceiptsFn func([]common.Hash) error
+type getProofsFn func([]*ProofReq) error
+
+// Peer stores ODR-specific information about LES peers that are able to serve requests
+type Peer struct {
+	id   string      // Unique identifier of the peer
+	head common.Hash // Hash of the peers latest known block
+
+	rep int32 // Simple peer reputation
+
+	GetBlockBodies getBlockBodiesFn
+	GetNodeData    getNodeDataFn
+	GetReceipts    getReceiptsFn
+	GetProofs      getProofsFn
+
+	version int // LES protocol version number
+}
+
+// newPeer creates a new ODR peer
+func newPeer(id string, version int, head common.Hash, getBlockBodies getBlockBodiesFn, getNodeData getNodeDataFn, getReceipts getReceiptsFn, getProofs getProofsFn) *Peer {
+	return &Peer{
+		id:             id,
+		head:           head,
+		GetBlockBodies: getBlockBodies,
+		GetNodeData:    getNodeData,
+		GetReceipts:    getReceipts,
+		GetProofs:      getProofs,
+		version:        version,
+	}
+}
+
+// Id returns a peer's ID string
+func (p *Peer) Id() string {
+	return p.id
+}
+
+
+// Promote increases the peer's reputation
+func (p *Peer) Promote() {
+	atomic.AddInt32(&p.rep, 1)
+}
+
+// Demote decreases the peer's reputation or leaves it at 0.
+func (p *Peer) Demote() {
+	for {
+		// Calculate the new reputation value
+		prev := atomic.LoadInt32(&p.rep)
+		next := prev / 2
+
+		// Try to update the old value
+		if atomic.CompareAndSwapInt32(&p.rep, prev, next) {
+			return
+		}
+	}
+}
+
+// peerSet represents the collection of active peer participating in the block
+// download procedure.
+type peerSet struct {
+	peers map[string]*Peer
+	lock  sync.RWMutex
+}
+
+// newPeerSet creates a new peer set top track the active download sources.
+func newPeerSet() *peerSet {
+	return &peerSet{
+		peers: make(map[string]*Peer),
+	}
+}
+
+// Register injects a new peer into the working set, or returns an error if the
+// peer is already known.
+func (ps *peerSet) Register(p *Peer) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if _, ok := ps.peers[p.id]; ok {
+		return errAlreadyRegistered
+	}
+	ps.peers[p.id] = p
+	return nil
+}
+
+// Unregister removes a remote peer from the active set, disabling any further
+// actions to/from that particular entity.
+func (ps *peerSet) Unregister(id string) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if _, ok := ps.peers[id]; !ok {
+		return errNotRegistered
+	}
+	delete(ps.peers, id)
+	return nil
+}
+
+// Peer retrieves the registered peer with the given id.
+func (ps *peerSet) Peer(id string) *Peer {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	return ps.peers[id]
+}
+
+// Len returns if the current number of peers in the set.
+func (ps *peerSet) Len() int {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	return len(ps.peers)
+}
+
+// AllPeers retrieves a flat list of all the peers within the set.
+func (ps *peerSet) AllPeers() []*Peer {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	list := make([]*Peer, 0, len(ps.peers))
+	for _, p := range ps.peers {
+		list = append(list, p)
+	}
+	return list
+}
+
+// BestPeers returns an ordered list of available peers, starting with the
+// highest reputation
+func (ps *peerSet) BestPeers() []*Peer {
+	list := ps.AllPeers()
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	for i := 0; i < len(list); i++ {
+		for j := i + 1; j < len(list); j++ {
+			if atomic.LoadInt32(&list[i].rep) < atomic.LoadInt32(&list[j].rep) {
+				list[i], list[j] = list[j], list[i]
+			}
+		}
+	}
+	return list
+}

core/bench_test.go

@@ -24,6 +24,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -168,8 +169,9 @@ func benchInsertChain(b *testing.B, disk bool, gen func(int, *BlockGen)) {
 	// Time the insertion of the new chain.
 	// State and blocks are stored in the same DB.
 	evmux := new(event.TypeMux)
-	chainman, _ := NewBlockChain(db, FakePow{}, evmux)
+	ca := access.NewDbChainAccess(db)
-	chainman.SetProcessor(NewBlockProcessor(db, FakePow{}, chainman, evmux))
+	chainman, _ := NewBlockChain(ca, FakePow{}, evmux)
+	chainman.SetProcessor(NewBlockProcessor(ca, FakePow{}, chainman, evmux))
 	defer chainman.Stop()
 	b.ReportAllocs()
 	b.ResetTimer()

core/block_processor.go

@@ -23,11 +23,11 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
-	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
@@ -43,7 +43,7 @@ const (
 )
 
 type BlockProcessor struct {
-	chainDb ethdb.Database
+	chainAccess *access.ChainAccess
 	// Mutex for locking the block processor. Blocks can only be handled one at a time
 	mutex sync.Mutex
 	// Canonical block chain
@@ -85,9 +85,9 @@ func (gp *GasPool) String() string {
 	return (*big.Int)(gp).String()
 }
 
-func NewBlockProcessor(db ethdb.Database, pow pow.PoW, blockchain *BlockChain, eventMux *event.TypeMux) *BlockProcessor {
+func NewBlockProcessor(ca *access.ChainAccess, pow pow.PoW, blockchain *BlockChain, eventMux *event.TypeMux) *BlockProcessor {
 	sm := &BlockProcessor{
-		chainDb:  db,
+		chainAccess: ca,
 		mem:      make(map[string]*big.Int),
 		Pow:      pow,
 		bc:       blockchain,
@@ -212,12 +212,12 @@ func (sm *BlockProcessor) Process(block *types.Block) (logs vm.Logs, receipts ty
 	defer sm.mutex.Unlock()
 
 	if sm.bc.HasBlock(block.Hash()) {
-		if _, err := state.New(block.Root(), sm.chainDb); err == nil {
+		if _, err := state.New(block.Root(), sm.chainAccess); err == nil {
 			return nil, nil, &KnownBlockError{block.Number(), block.Hash()}
 		}
 	}
 	if parent := sm.bc.GetBlock(block.ParentHash()); parent != nil {
-		if _, err := state.New(parent.Root(), sm.chainDb); err == nil {
+		if _, err := state.New(parent.Root(), sm.chainAccess); err == nil {
 			return sm.processWithParent(block, parent)
 		}
 	}
@@ -226,7 +226,7 @@ func (sm *BlockProcessor) Process(block *types.Block) (logs vm.Logs, receipts ty
 
 func (sm *BlockProcessor) processWithParent(block, parent *types.Block) (logs vm.Logs, receipts types.Receipts, err error) {
 	// Create a new state based on the parent's root (e.g., create copy)
-	state, err := state.New(parent.Root(), sm.chainDb)
+	state, err := state.New(parent.Root(), sm.chainAccess)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -370,7 +370,7 @@ func (sm *BlockProcessor) VerifyUncles(statedb *state.StateDB, block, parent *ty
 // GetBlockReceipts returns the receipts beloniging to the block hash
 func (sm *BlockProcessor) GetBlockReceipts(bhash common.Hash) types.Receipts {
 	if block := sm.BlockChain().GetBlock(bhash); block != nil {
-		return GetBlockReceipts(sm.chainDb, block.Hash())
+		return GetBlockReceipts(sm.chainAccess, block.Hash())
 	}
 
 	return nil
@@ -380,7 +380,7 @@ func (sm *BlockProcessor) GetBlockReceipts(bhash common.Hash) types.Receipts {
 // where it tries to get it from the (updated) method which gets them from the receipts or
 // the depricated way by re-processing the block.
 func (sm *BlockProcessor) GetLogs(block *types.Block) (logs vm.Logs, err error) {
-	receipts := GetBlockReceipts(sm.chainDb, block.Hash())
+	receipts := GetBlockReceipts(sm.chainAccess, block.Hash())
 	// coalesce logs
 	for _, receipt := range receipts {
 		logs = append(logs, receipt.Logs...)

core/block_processor_test.go

@@ -22,6 +22,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -32,21 +33,22 @@ import (
 
 func proc() (*BlockProcessor, *BlockChain) {
 	db, _ := ethdb.NewMemDatabase()
+	ca := access.NewDbChainAccess(db)
 	var mux event.TypeMux
 
 	WriteTestNetGenesisBlock(db, 0)
-	blockchain, err := NewBlockChain(db, thePow(), &mux)
+	blockchain, err := NewBlockChain(ca, thePow(), &mux)
 	if err != nil {
 		fmt.Println(err)
 	}
-	return NewBlockProcessor(db, ezp.New(), blockchain, &mux), blockchain
+	return NewBlockProcessor(ca, ezp.New(), blockchain, &mux), blockchain
 }
 
 func TestNumber(t *testing.T) {
 	pow := ezp.New()
 	_, chain := proc()
 
-	statedb, _ := state.New(chain.Genesis().Root(), chain.chainDb)
+	statedb, _ := state.New(chain.Genesis().Root(), access.NewDbChainAccess(chain.chainDb))
 	header := makeHeader(chain.Genesis(), statedb)
 	header.Number = big.NewInt(3)
 	err := ValidateHeader(pow, header, chain.Genesis().Header(), false, false)
@@ -82,7 +84,7 @@ func TestPutReceipt(t *testing.T) {
 	}}
 
 	PutReceipts(db, types.Receipts{receipt})
-	receipt = GetReceipt(db, common.Hash{})
+	receipt = GetReceipt(access.NewDbChainAccess(db), common.Hash{})
 	if receipt == nil {
 		t.Error("expected to get 1 receipt, got none.")
 	}

core/blockchain.go

@@ -31,6 +31,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -43,6 +44,7 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 	"github.com/hashicorp/golang-lru"
+	"golang.org/x/net/context"
 )
 
 var (
@@ -64,6 +66,7 @@ const (
 )
 
 type BlockChain struct {
+	chainAccess  *access.ChainAccess
 	chainDb      ethdb.Database
 	processor    types.BlockProcessor
 	eventMux     *event.TypeMux
@@ -95,7 +98,7 @@ type BlockChain struct {
 	rand *mrand.Rand
 }
 
-func NewBlockChain(chainDb ethdb.Database, pow pow.PoW, mux *event.TypeMux) (*BlockChain, error) {
+func NewBlockChain(chainAccess *access.ChainAccess, pow pow.PoW, mux *event.TypeMux) (*BlockChain, error) {
 	headerCache, _ := lru.New(headerCacheLimit)
 	bodyCache, _ := lru.New(bodyCacheLimit)
 	bodyRLPCache, _ := lru.New(bodyCacheLimit)
@@ -104,7 +107,8 @@ func NewBlockChain(chainDb ethdb.Database, pow pow.PoW, mux *event.TypeMux) (*Bl
 	futureBlocks, _ := lru.New(maxFutureBlocks)
 
 	bc := &BlockChain{
-		chainDb:      chainDb,
+		chainDb:      chainAccess.Db(),
+		chainAccess:  chainAccess,
 		eventMux:     mux,
 		quit:         make(chan struct{}),
 		headerCache:  headerCache,
@@ -128,7 +132,7 @@ func NewBlockChain(chainDb ethdb.Database, pow pow.PoW, mux *event.TypeMux) (*Bl
 		if err != nil {
 			return nil, err
 		}
-		bc.genesisBlock, err = WriteGenesisBlock(chainDb, reader)
+		bc.genesisBlock, err = WriteGenesisBlock(bc.chainDb, reader)
 		if err != nil {
 			return nil, err
 		}
@@ -344,8 +348,14 @@ func (self *BlockChain) SetProcessor(proc types.BlockProcessor) {
 	self.processor = proc
 }
 
+// State returns a new StateDB for the current block
 func (self *BlockChain) State() (*state.StateDB, error) {
-	return state.New(self.CurrentBlock().Root(), self.chainDb)
+	return state.New(self.CurrentBlock().Root(), self.chainAccess)
+}
+
+// StateOdr returns a new StateDB for the current block with ODR enabled
+func (self *BlockChain) StateOdr(ctx context.Context) (*state.StateDB, error) {
+	return state.NewOdr(ctx, self.CurrentBlock().Root(), self.chainAccess)
 }
 
 // Reset purges the entire blockchain, restoring it to its genesis state.
@@ -482,12 +492,18 @@ func (self *BlockChain) GetHeaderByNumber(number uint64) *types.Header {
 // GetBody retrieves a block body (transactions and uncles) from the database by
 // hash, caching it if found.
 func (self *BlockChain) GetBody(hash common.Hash) *types.Body {
+	return self.GetBodyOdr(access.NoOdr, hash)
+}
+
+// GetBodyOdr retrieves a block body (transactions and uncles) from the database
+// or network by hash, caching it if found.
+func (self *BlockChain) GetBodyOdr(ctx context.Context, hash common.Hash) *types.Body {
 	// Short circuit if the body's already in the cache, retrieve otherwise
 	if cached, ok := self.bodyCache.Get(hash); ok {
 		body := cached.(*types.Body)
 		return body
 	}
-	body := GetBody(self.chainDb, hash)
+	body := GetBodyOdr(ctx, self.chainAccess, hash)
 	if body == nil {
 		return nil
 	}
@@ -499,11 +515,17 @@ func (self *BlockChain) GetBody(hash common.Hash) *types.Body {
 // GetBodyRLP retrieves a block body in RLP encoding from the database by hash,
 // caching it if found.
 func (self *BlockChain) GetBodyRLP(hash common.Hash) rlp.RawValue {
+	return self.GetBodyRLPOdr(access.NoOdr, hash)
+}
+
+// GetBodyRLPOdr retrieves a block body in RLP encoding from the database or
+// network by hash, caching it if found.
+func (self *BlockChain) GetBodyRLPOdr(ctx context.Context, hash common.Hash) rlp.RawValue {
 	// Short circuit if the body's already in the cache, retrieve otherwise
 	if cached, ok := self.bodyRLPCache.Get(hash); ok {
 		return cached.(rlp.RawValue)
 	}
-	body := GetBodyRLP(self.chainDb, hash)
+	body := GetBodyRLPOdr(ctx, self.chainAccess, hash)
 	if len(body) == 0 {
 		return nil
 	}
@@ -536,11 +558,16 @@ func (bc *BlockChain) HasBlock(hash common.Hash) bool {
 
 // GetBlock retrieves a block from the database by hash, caching it if found.
 func (self *BlockChain) GetBlock(hash common.Hash) *types.Block {
+	return self.GetBlockOdr(access.NoOdr, hash)
+}
+
+// GetBlockOdr retrieves a block from the database or network by hash, caching it if found.
+func (self *BlockChain) GetBlockOdr(ctx context.Context, hash common.Hash) *types.Block {
 	// Short circuit if the block's already in the cache, retrieve otherwise
 	if block, ok := self.blockCache.Get(hash); ok {
 		return block.(*types.Block)
 	}
-	block := GetBlock(self.chainDb, hash)
+	block := GetBlockOdr(ctx, self.chainAccess, hash)
 	if block == nil {
 		return nil
 	}
@@ -552,11 +579,17 @@ func (self *BlockChain) GetBlock(hash common.Hash) *types.Block {
 // GetBlockByNumber retrieves a block from the database by number, caching it
 // (associated with its hash) if found.
 func (self *BlockChain) GetBlockByNumber(number uint64) *types.Block {
+	return self.GetBlockByNumberOdr(access.NoOdr, number)
+}
+
+// GetBlockByNumberOdr retrieves a block from the database or network by number,
+// caching it (associated with its hash) if found.
+func (self *BlockChain) GetBlockByNumberOdr(ctx context.Context, number uint64) *types.Block {
 	hash := GetCanonicalHash(self.chainDb, number)
 	if hash == (common.Hash{}) {
 		return nil
 	}
-	return self.GetBlock(hash)
+	return self.GetBlockOdr(ctx, hash)
 }
 
 // GetBlockHashesFromHash retrieves a number of block hashes starting at a given
@@ -1209,7 +1242,7 @@ func (self *BlockChain) reorg(oldBlock, newBlock *types.Block) error {
 		if err := PutTransactions(self.chainDb, block, block.Transactions()); err != nil {
 			return err
 		}
-		receipts := GetBlockReceipts(self.chainDb, block.Hash())
+		receipts := GetBlockReceipts(self.chainAccess, block.Hash())
 		// write receipts
 		if err := PutReceipts(self.chainDb, receipts); err != nil {
 			return err

core/blockchain_test.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/ethereum/ethash"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -51,13 +52,14 @@ func thePow() pow.PoW {
 func theBlockChain(db ethdb.Database, t *testing.T) *BlockChain {
 	var eventMux event.TypeMux
 	WriteTestNetGenesisBlock(db, 0)
-	blockchain, err := NewBlockChain(db, thePow(), &eventMux)
+	ca := access.NewDbChainAccess(db)
+	blockchain, err := NewBlockChain(ca, thePow(), &eventMux)
 	if err != nil {
 		t.Error("failed creating chainmanager:", err)
 		t.FailNow()
 		return nil
 	}
-	blockMan := NewBlockProcessor(db, nil, blockchain, &eventMux)
+	blockMan := NewBlockProcessor(ca, nil, blockchain, &eventMux)
 	blockchain.SetProcessor(blockMan)
 
 	return blockchain
@@ -138,8 +140,8 @@ func testBlockChainImport(chain []*types.Block, processor *BlockProcessor) error
 		}
 		// Manually insert the block into the database, but don't reorganize (allows subsequent testing)
 		processor.bc.mu.Lock()
-		WriteTd(processor.chainDb, block.Hash(), new(big.Int).Add(block.Difficulty(), processor.bc.GetTd(block.ParentHash())))
+		WriteTd(processor.chainAccess.Db(), block.Hash(), new(big.Int).Add(block.Difficulty(), processor.bc.GetTd(block.ParentHash())))
-		WriteBlock(processor.chainDb, block)
+		WriteBlock(processor.chainAccess.Db(), block)
 		processor.bc.mu.Unlock()
 	}
 	return nil
@@ -155,8 +157,8 @@ func testHeaderChainImport(chain []*types.Header, processor *BlockProcessor) err
 		}
 		// Manually insert the header into the database, but don't reorganize (allows subsequent testing)
 		processor.bc.mu.Lock()
-		WriteTd(processor.chainDb, header.Hash(), new(big.Int).Add(header.Difficulty, processor.bc.GetTd(header.ParentHash)))
+		WriteTd(processor.chainAccess.Db(), header.Hash(), new(big.Int).Add(header.Difficulty, processor.bc.GetTd(header.ParentHash)))
-		WriteHeader(processor.chainDb, header)
+		WriteHeader(processor.chainAccess.Db(), header)
 		processor.bc.mu.Unlock()
 	}
 	return nil
@@ -452,7 +454,8 @@ func makeBlockChainWithDiff(genesis *types.Block, d []int, seed byte) []*types.B
 
 func chm(genesis *types.Block, db ethdb.Database) *BlockChain {
 	var eventMux event.TypeMux
-	bc := &BlockChain{chainDb: db, genesisBlock: genesis, eventMux: &eventMux, pow: FakePow{}, rand: rand.New(rand.NewSource(0))}
+	ca := access.NewDbChainAccess(db)
+	bc := &BlockChain{chainAccess: ca, chainDb: db, genesisBlock: genesis, eventMux: &eventMux, pow: FakePow{}, rand: rand.New(rand.NewSource(0))}
 	bc.headerCache, _ = lru.New(100)
 	bc.bodyCache, _ = lru.New(100)
 	bc.bodyRLPCache, _ = lru.New(100)
@@ -587,7 +590,7 @@ func testReorgBadHashes(t *testing.T, full bool) {
 		defer func() { delete(BadHashes, headers[3].Hash()) }()
 	}
 	// Create a new chain manager and check it rolled back the state
-	ncm, err := NewBlockChain(db, FakePow{}, new(event.TypeMux))
+	ncm, err := NewBlockChain(access.NewDbChainAccess(db), FakePow{}, new(event.TypeMux))
 	if err != nil {
 		t.Fatalf("failed to create new chain manager: %v", err)
 	}
@@ -708,19 +711,21 @@ func TestFastVsFullChains(t *testing.T) {
 	})
 	// Import the chain as an archive node for the comparison baseline
 	archiveDb, _ := ethdb.NewMemDatabase()
+	archiveCa := access.NewDbChainAccess(archiveDb)
 	WriteGenesisBlockForTesting(archiveDb, GenesisAccount{address, funds})
 
-	archive, _ := NewBlockChain(archiveDb, FakePow{}, new(event.TypeMux))
+	archive, _ := NewBlockChain(archiveCa, FakePow{}, new(event.TypeMux))
-	archive.SetProcessor(NewBlockProcessor(archiveDb, FakePow{}, archive, new(event.TypeMux)))
+	archive.SetProcessor(NewBlockProcessor(archiveCa, FakePow{}, archive, new(event.TypeMux)))
 
 	if n, err := archive.InsertChain(blocks); err != nil {
 		t.Fatalf("failed to process block %d: %v", n, err)
 	}
 	// Fast import the chain as a non-archive node to test
 	fastDb, _ := ethdb.NewMemDatabase()
+	fastCa := access.NewDbChainAccess(fastDb)
 	WriteGenesisBlockForTesting(fastDb, GenesisAccount{address, funds})
-	fast, _ := NewBlockChain(fastDb, FakePow{}, new(event.TypeMux))
+	fast, _ := NewBlockChain(fastCa, FakePow{}, new(event.TypeMux))
-	fast.SetProcessor(NewBlockProcessor(fastDb, FakePow{}, fast, new(event.TypeMux)))
+	fast.SetProcessor(NewBlockProcessor(fastCa, FakePow{}, fast, new(event.TypeMux)))
 
 	headers := make([]*types.Header, len(blocks))
 	for i, block := range blocks {
@@ -749,7 +754,7 @@ func TestFastVsFullChains(t *testing.T) {
 		} else if types.CalcUncleHash(fblock.Uncles()) != types.CalcUncleHash(ablock.Uncles()) {
 			t.Errorf("block #%d [%x]: uncles mismatch: have %v, want %v", num, hash, fblock.Uncles(), ablock.Uncles())
 		}
-		if freceipts, areceipts := GetBlockReceipts(fastDb, hash), GetBlockReceipts(archiveDb, hash); types.DeriveSha(freceipts) != types.DeriveSha(areceipts) {
+		if freceipts, areceipts := GetBlockReceipts(fastCa, hash), GetBlockReceipts(archiveCa, hash); types.DeriveSha(freceipts) != types.DeriveSha(areceipts) {
 			t.Errorf("block #%d [%x]: receipts mismatch: have %v, want %v", num, hash, freceipts, areceipts)
 		}
 	}
@@ -794,10 +799,10 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 	}
 	// Import the chain as an archive node and ensure all pointers are updated
 	archiveDb, _ := ethdb.NewMemDatabase()
+	archiveCa := access.NewDbChainAccess(archiveDb)
 	WriteGenesisBlockForTesting(archiveDb, GenesisAccount{address, funds})
-
+	archive, _ := NewBlockChain(archiveCa, FakePow{}, new(event.TypeMux))
-	archive, _ := NewBlockChain(archiveDb, FakePow{}, new(event.TypeMux))
+	archive.SetProcessor(NewBlockProcessor(archiveCa, FakePow{}, archive, new(event.TypeMux)))
-	archive.SetProcessor(NewBlockProcessor(archiveDb, FakePow{}, archive, new(event.TypeMux)))
 
 	if n, err := archive.InsertChain(blocks); err != nil {
 		t.Fatalf("failed to process block %d: %v", n, err)
@@ -808,9 +813,10 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 
 	// Import the chain as a non-archive node and ensure all pointers are updated
 	fastDb, _ := ethdb.NewMemDatabase()
+	fastCa := access.NewDbChainAccess(fastDb)
 	WriteGenesisBlockForTesting(fastDb, GenesisAccount{address, funds})
-	fast, _ := NewBlockChain(fastDb, FakePow{}, new(event.TypeMux))
+	fast, _ := NewBlockChain(fastCa, FakePow{}, new(event.TypeMux))
-	fast.SetProcessor(NewBlockProcessor(fastDb, FakePow{}, fast, new(event.TypeMux)))
+	fast.SetProcessor(NewBlockProcessor(fastCa, FakePow{}, fast, new(event.TypeMux)))
 
 	headers := make([]*types.Header, len(blocks))
 	for i, block := range blocks {
@@ -828,9 +834,10 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 
 	// Import the chain as a light node and ensure all pointers are updated
 	lightDb, _ := ethdb.NewMemDatabase()
+	lightCa := access.NewDbChainAccess(lightDb)
 	WriteGenesisBlockForTesting(lightDb, GenesisAccount{address, funds})
-	light, _ := NewBlockChain(lightDb, FakePow{}, new(event.TypeMux))
+	light, _ := NewBlockChain(lightCa, FakePow{}, new(event.TypeMux))
-	light.SetProcessor(NewBlockProcessor(lightDb, FakePow{}, light, new(event.TypeMux)))
+	light.SetProcessor(NewBlockProcessor(lightCa, FakePow{}, light, new(event.TypeMux)))
 
 	if n, err := light.InsertHeaderChain(headers, 1); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
@@ -895,8 +902,9 @@ func TestChainTxReorgs(t *testing.T) {
 	})
 	// Import the chain. This runs all block validation rules.
 	evmux := &event.TypeMux{}
-	chainman, _ := NewBlockChain(db, FakePow{}, evmux)
+	ca := access.NewDbChainAccess(db)
-	chainman.SetProcessor(NewBlockProcessor(db, FakePow{}, chainman, evmux))
+	chainman, _ := NewBlockChain(ca, FakePow{}, evmux)
+	chainman.SetProcessor(NewBlockProcessor(ca, FakePow{}, chainman, evmux))
 	if i, err := chainman.InsertChain(chain); err != nil {
 		t.Fatalf("failed to insert original chain[%d]: %v", i, err)
 	}
@@ -929,7 +937,7 @@ func TestChainTxReorgs(t *testing.T) {
 		if GetTransaction(db, tx.Hash()) != nil {
 			t.Errorf("drop %d: tx found while shouldn't have been", i)
 		}
-		if GetReceipt(db, tx.Hash()) != nil {
+		if GetReceipt(ca, tx.Hash()) != nil {
 			t.Errorf("drop %d: receipt found while shouldn't have been", i)
 		}
 	}
@@ -938,7 +946,7 @@ func TestChainTxReorgs(t *testing.T) {
 		if GetTransaction(db, tx.Hash()) == nil {
 			t.Errorf("add %d: expected tx to be found", i)
 		}
-		if GetReceipt(db, tx.Hash()) == nil {
+		if GetReceipt(ca, tx.Hash()) == nil {
 			t.Errorf("add %d: expected receipt to be found", i)
 		}
 	}
@@ -947,7 +955,7 @@ func TestChainTxReorgs(t *testing.T) {
 		if GetTransaction(db, tx.Hash()) == nil {
 			t.Errorf("share %d: expected tx to be found", i)
 		}
-		if GetReceipt(db, tx.Hash()) == nil {
+		if GetReceipt(ca, tx.Hash()) == nil {
 			t.Errorf("share %d: expected receipt to be found", i)
 		}
 	}

core/chain_makers.go

@@ -21,6 +21,7 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -164,7 +165,7 @@ func (b *BlockGen) OffsetTime(seconds int64) {
 // values. Inserting them into BlockChain requires use of FakePow or
 // a similar non-validating proof of work implementation.
 func GenerateChain(parent *types.Block, db ethdb.Database, n int, gen func(int, *BlockGen)) ([]*types.Block, []types.Receipts) {
-	statedb, err := state.New(parent.Root(), db)
+	statedb, err := state.New(parent.Root(), access.NewDbChainAccess(db))
 	if err != nil {
 		panic(err)
 	}
@@ -222,8 +223,9 @@ func newCanonical(n int, full bool) (ethdb.Database, *BlockProcessor, error) {
 	// Initialize a fresh chain with only a genesis block
 	genesis, _ := WriteTestNetGenesisBlock(db, 0)
 
-	blockchain, _ := NewBlockChain(db, FakePow{}, evmux)
+	ca := access.NewDbChainAccess(db)
-	processor := NewBlockProcessor(db, FakePow{}, blockchain, evmux)
+	blockchain, _ := NewBlockChain(ca, FakePow{}, evmux)
+	processor := NewBlockProcessor(ca, FakePow{}, blockchain, evmux)
 	processor.bc.SetProcessor(processor)
 
 	// Create and inject the requested chain

core/chain_makers_test.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"math/big"
 
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -77,8 +78,9 @@ func ExampleGenerateChain() {
 
 	// Import the chain. This runs all block validation rules.
 	evmux := &event.TypeMux{}
-	chainman, _ := NewBlockChain(db, FakePow{}, evmux)
+	ca := access.NewDbChainAccess(db)
-	chainman.SetProcessor(NewBlockProcessor(db, FakePow{}, chainman, evmux))
+	chainman, _ := NewBlockChain(ca, FakePow{}, evmux)
+	chainman.SetProcessor(NewBlockProcessor(ca, FakePow{}, chainman, evmux))
 	if i, err := chainman.InsertChain(chain); err != nil {
 		fmt.Printf("insert error (block %d): %v\n", i, err)
 		return

core/chain_util.go

@@ -23,12 +23,15 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
+	"github.com/ethereum/go-ethereum/core/requests"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
+	"golang.org/x/net/context"
 )
 
 var (
@@ -182,16 +185,31 @@ func GetHeader(db ethdb.Database, hash common.Hash) *types.Header {
 	return header
 }
 
-// GetBodyRLP retrieves the block body (transactions and uncles) in RLP encoding.
+// GetBodyRLP retrieves the block body (transactions and uncles) from the
-func GetBodyRLP(db ethdb.Database, hash common.Hash) rlp.RawValue {
+// database in RLP encoding.
-	data, _ := db.Get(append(append(blockPrefix, hash[:]...), bodySuffix...))
+func GetBodyRLP(ca *access.ChainAccess, hash common.Hash) rlp.RawValue {
-	return data
+	return GetBodyRLPOdr(access.NoOdr, ca, hash)
+}
+
+// GetBodyRLPOdr retrieves the block body (transactions and uncles) from the
+// database or network in RLP encoding.
+func GetBodyRLPOdr(ctx context.Context, ca *access.ChainAccess, hash common.Hash) rlp.RawValue {
+	//fmt.Println("request block %v", hash)
+	r := requests.NewBlockAccess(ca.Db(), hash, GetHeader)
+	ca.Retrieve(ctx, r)
+	return r.GetRlp()
 }
 
 // GetBody retrieves the block body (transactons, uncles) corresponding to the
-// hash, nil if none found.
+// hash from the database, nil if none found.
-func GetBody(db ethdb.Database, hash common.Hash) *types.Body {
+func GetBody(ca *access.ChainAccess, hash common.Hash) *types.Body {
-	data := GetBodyRLP(db, hash)
+	return GetBodyOdr(access.NoOdr, ca, hash)
+}
+
+// GetBodyOdr retrieves the block body (transactons, uncles) corresponding to the
+// hash from the database or network, nil if none found.
+func GetBodyOdr(ctx context.Context, ca *access.ChainAccess, hash common.Hash) *types.Body {
+	data := GetBodyRLPOdr(ctx, ca, hash)
 	if len(data) == 0 {
 		return nil
 	}
@@ -218,15 +236,21 @@ func GetTd(db ethdb.Database, hash common.Hash) *big.Int {
 	return td
 }
 
-// GetBlock retrieves an entire block corresponding to the hash, assembling it
+// GetBlock retrieves an entire block from the database corresponding to the
-// back from the stored header and body.
+// hash, assembling it back from the stored header and body.
-func GetBlock(db ethdb.Database, hash common.Hash) *types.Block {
+func GetBlock(ca *access.ChainAccess, hash common.Hash) *types.Block {
+	return GetBlockOdr(access.NoOdr, ca, hash)
+}
+
+// GetBlockOdr retrieves an entire block from database or network corresponding
+// to the hash, assembling it back from the stored header and body.
+func GetBlockOdr(ctx context.Context, ca *access.ChainAccess, hash common.Hash) *types.Block {
 	// Retrieve the block header and body contents
-	header := GetHeader(db, hash)
+	header := GetHeader(ca.Db(), hash)
 	if header == nil {
 		return nil
 	}
-	body := GetBody(db, hash)
+	body := GetBodyOdr(ctx, ca, hash)
 	if body == nil {
 		return nil
 	}

core/chain_util_test.go

@@ -24,6 +24,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -121,6 +122,7 @@ func TestHeaderStorage(t *testing.T) {
 // Tests block body storage and retrieval operations.
 func TestBodyStorage(t *testing.T) {
 	db, _ := ethdb.NewMemDatabase()
+	ca := access.NewDbChainAccess(db)
 
 	// Create a test body to move around the database and make sure it's really new
 	body := &types.Body{Uncles: []*types.Header{{Extra: []byte("test header")}}}
@@ -129,19 +131,19 @@ func TestBodyStorage(t *testing.T) {
 	rlp.Encode(hasher, body)
 	hash := common.BytesToHash(hasher.Sum(nil))
 
-	if entry := GetBody(db, hash); entry != nil {
+	if entry := GetBody(ca, hash); entry != nil {
 		t.Fatalf("Non existent body returned: %v", entry)
 	}
 	// Write and verify the body in the database
 	if err := WriteBody(db, hash, body); err != nil {
 		t.Fatalf("Failed to write body into database: %v", err)
 	}
-	if entry := GetBody(db, hash); entry == nil {
+	if entry := GetBody(ca, hash); entry == nil {
 		t.Fatalf("Stored body not found")
 	} else if types.DeriveSha(types.Transactions(entry.Transactions)) != types.DeriveSha(types.Transactions(body.Transactions)) || types.CalcUncleHash(entry.Uncles) != types.CalcUncleHash(body.Uncles) {
 		t.Fatalf("Retrieved body mismatch: have %v, want %v", entry, body)
 	}
-	if entry := GetBodyRLP(db, hash); entry == nil {
+	if entry := GetBodyRLP(ca, hash); entry == nil {
 		t.Fatalf("Stored body RLP not found")
 	} else {
 		hasher := sha3.NewKeccak256()
@@ -153,7 +155,7 @@ func TestBodyStorage(t *testing.T) {
 	}
 	// Delete the body and verify the execution
 	DeleteBody(db, hash)
-	if entry := GetBody(db, hash); entry != nil {
+	if entry := GetBody(ca, hash); entry != nil {
 		t.Fatalf("Deleted body returned: %v", entry)
 	}
 }
@@ -161,6 +163,7 @@ func TestBodyStorage(t *testing.T) {
 // Tests block storage and retrieval operations.
 func TestBlockStorage(t *testing.T) {
 	db, _ := ethdb.NewMemDatabase()
+	ca := access.NewDbChainAccess(db)
 
 	// Create a test block to move around the database and make sure it's really new
 	block := types.NewBlockWithHeader(&types.Header{
@@ -169,20 +172,20 @@ func TestBlockStorage(t *testing.T) {
 		TxHash:      types.EmptyRootHash,
 		ReceiptHash: types.EmptyRootHash,
 	})
-	if entry := GetBlock(db, block.Hash()); entry != nil {
+	if entry := GetBlock(ca, block.Hash()); entry != nil {
 		t.Fatalf("Non existent block returned: %v", entry)
 	}
 	if entry := GetHeader(db, block.Hash()); entry != nil {
 		t.Fatalf("Non existent header returned: %v", entry)
 	}
-	if entry := GetBody(db, block.Hash()); entry != nil {
+	if entry := GetBody(ca, block.Hash()); entry != nil {
 		t.Fatalf("Non existent body returned: %v", entry)
 	}
 	// Write and verify the block in the database
 	if err := WriteBlock(db, block); err != nil {
 		t.Fatalf("Failed to write block into database: %v", err)
 	}
-	if entry := GetBlock(db, block.Hash()); entry == nil {
+	if entry := GetBlock(ca, block.Hash()); entry == nil {
 		t.Fatalf("Stored block not found")
 	} else if entry.Hash() != block.Hash() {
 		t.Fatalf("Retrieved block mismatch: have %v, want %v", entry, block)
@@ -192,20 +195,20 @@ func TestBlockStorage(t *testing.T) {
 	} else if entry.Hash() != block.Header().Hash() {
 		t.Fatalf("Retrieved header mismatch: have %v, want %v", entry, block.Header())
 	}
-	if entry := GetBody(db, block.Hash()); entry == nil {
+	if entry := GetBody(ca, block.Hash()); entry == nil {
 		t.Fatalf("Stored body not found")
 	} else if types.DeriveSha(types.Transactions(entry.Transactions)) != types.DeriveSha(block.Transactions()) || types.CalcUncleHash(entry.Uncles) != types.CalcUncleHash(block.Uncles()) {
 		t.Fatalf("Retrieved body mismatch: have %v, want %v", entry, &types.Body{block.Transactions(), block.Uncles()})
 	}
 	// Delete the block and verify the execution
 	DeleteBlock(db, block.Hash())
-	if entry := GetBlock(db, block.Hash()); entry != nil {
+	if entry := GetBlock(ca, block.Hash()); entry != nil {
 		t.Fatalf("Deleted block returned: %v", entry)
 	}
 	if entry := GetHeader(db, block.Hash()); entry != nil {
 		t.Fatalf("Deleted header returned: %v", entry)
 	}
-	if entry := GetBody(db, block.Hash()); entry != nil {
+	if entry := GetBody(ca, block.Hash()); entry != nil {
 		t.Fatalf("Deleted body returned: %v", entry)
 	}
 }
@@ -213,6 +216,7 @@ func TestBlockStorage(t *testing.T) {
 // Tests that partial block contents don't get reassembled into full blocks.
 func TestPartialBlockStorage(t *testing.T) {
 	db, _ := ethdb.NewMemDatabase()
+	ca := access.NewDbChainAccess(db)
 	block := types.NewBlockWithHeader(&types.Header{
 		Extra:       []byte("test block"),
 		UncleHash:   types.EmptyUncleHash,
@@ -223,7 +227,7 @@ func TestPartialBlockStorage(t *testing.T) {
 	if err := WriteHeader(db, block.Header()); err != nil {
 		t.Fatalf("Failed to write header into database: %v", err)
 	}
-	if entry := GetBlock(db, block.Hash()); entry != nil {
+	if entry := GetBlock(ca, block.Hash()); entry != nil {
 		t.Fatalf("Non existent block returned: %v", entry)
 	}
 	DeleteHeader(db, block.Hash())
@@ -232,7 +236,7 @@ func TestPartialBlockStorage(t *testing.T) {
 	if err := WriteBody(db, block.Hash(), &types.Body{block.Transactions(), block.Uncles()}); err != nil {
 		t.Fatalf("Failed to write body into database: %v", err)
 	}
-	if entry := GetBlock(db, block.Hash()); entry != nil {
+	if entry := GetBlock(ca, block.Hash()); entry != nil {
 		t.Fatalf("Non existent block returned: %v", entry)
 	}
 	DeleteBody(db, block.Hash())
@@ -244,7 +248,7 @@ func TestPartialBlockStorage(t *testing.T) {
 	if err := WriteBody(db, block.Hash(), &types.Body{block.Transactions(), block.Uncles()}); err != nil {
 		t.Fatalf("Failed to write body into database: %v", err)
 	}
-	if entry := GetBlock(db, block.Hash()); entry == nil {
+	if entry := GetBlock(ca, block.Hash()); entry == nil {
 		t.Fatalf("Stored block not found")
 	} else if entry.Hash() != block.Hash() {
 		t.Fatalf("Retrieved block mismatch: have %v, want %v", entry, block)

core/genesis.go

@@ -25,6 +25,7 @@ import (
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -61,7 +62,8 @@ func WriteGenesisBlock(chainDb ethdb.Database, reader io.Reader) (*types.Block,
 	}
 
 	// creating with empty hash always works
-	statedb, _ := state.New(common.Hash{}, chainDb)
+	ca := access.NewDbChainAccess(chainDb)
+	statedb, _ := state.New(common.Hash{}, ca)
 	for addr, account := range genesis.Alloc {
 		address := common.HexToAddress(addr)
 		statedb.AddBalance(address, common.String2Big(account.Balance))
@@ -85,7 +87,7 @@ func WriteGenesisBlock(chainDb ethdb.Database, reader io.Reader) (*types.Block,
 		Root:       root,
 	}, nil, nil, nil)
 
-	if block := GetBlock(chainDb, block.Hash()); block != nil {
+	if block := GetBlock(ca, block.Hash()); block != nil {
 		glog.V(logger.Info).Infoln("Genesis block already in chain. Writing canonical number")
 		err := WriteCanonicalHash(chainDb, block.Hash(), block.NumberU64())
 		if err != nil {
@@ -118,7 +120,7 @@ func WriteGenesisBlock(chainDb ethdb.Database, reader io.Reader) (*types.Block,
 // GenesisBlockForTesting creates a block in which addr has the given wei balance.
 // The state trie of the block is written to db. the passed db needs to contain a state root
 func GenesisBlockForTesting(db ethdb.Database, addr common.Address, balance *big.Int) *types.Block {
-	statedb, _ := state.New(common.Hash{}, db)
+	statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 	obj := statedb.GetOrNewStateObject(addr)
 	obj.SetBalance(balance)
 	root, err := statedb.Commit()

core/manager.go

@@ -18,6 +18,7 @@ package core
 
 import (
 	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 )
@@ -29,6 +30,7 @@ type Backend interface {
 	BlockChain() *BlockChain
 	TxPool() *TxPool
 	ChainDb() ethdb.Database
+	ChainAccess() *access.ChainAccess
 	DappDb() ethdb.Database
 	EventMux() *event.TypeMux
 }

core/requests/block_access.go

@@ -0,0 +1,204 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package requests
+
+import (
+	"bytes"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/core/access"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+var (
+	blockReceiptsPre = []byte("receipts-block-")
+	blockPrefix      = []byte("block-")
+	bodySuffix       = []byte("-body")
+)
+
+// BlockAccess is the ODR request type for block bodies
+type BlockAccess struct {
+	access.ObjectAccess
+	db        ethdb.Database
+	blockHash common.Hash
+	rlp       []byte
+	getHeader getHeaderFn
+}
+
+type getHeaderFn func(db ethdb.Database, hash common.Hash) *types.Header
+
+// NewBlockAccess creates a new BlockAccess request
+func NewBlockAccess(db ethdb.Database, blockHash common.Hash, getHeader getHeaderFn) *BlockAccess {
+	return &BlockAccess{db: db, blockHash: blockHash, getHeader: getHeader}
+}
+
+// GetRlp returns the block body rlp data stored in memory after a successful request
+func (self *BlockAccess) GetRlp() []byte {
+	return self.rlp
+}
+
+// Request sends an ODR request to the LES network (implementation of access.ObjectAccess)
+func (self *BlockAccess) Request(peer *access.Peer) error {
+	glog.V(access.LogLevel).Infof("ODR: requesting body of block %08x from peer %v", self.blockHash[:4], peer.Id())
+	return peer.GetBlockBodies([]common.Hash{self.blockHash})
+}
+
+// Valid processes an ODR request reply message from the LES network
+// returns true and stores results in memory if the message was a valid reply
+// to the request (implementation of access.ObjectAccess)
+func (self *BlockAccess) Valid(msg *access.Msg) bool {
+	glog.V(access.LogLevel).Infof("ODR: validating body of block %08x", self.blockHash[:4])
+	if msg.MsgType != access.MsgBlockBodies {
+		glog.V(access.LogLevel).Infof("ODR: invalid message type")
+		return false
+	}
+	bodies := msg.Obj.([]*types.Body)
+	if len(bodies) != 1 {
+		glog.V(access.LogLevel).Infof("ODR: invalid number of entries: %d", len(bodies))
+		return false
+	}
+	body := bodies[0]
+	header := self.getHeader(self.db, self.blockHash)
+	if header == nil {
+		glog.V(access.LogLevel).Infof("ODR: header not found for block %08x", self.blockHash[:4])
+		return false
+	}
+	txHash := types.DeriveSha(types.Transactions(body.Transactions))
+	if header.TxHash != txHash {
+		glog.V(access.LogLevel).Infof("ODR: header.TxHash %08x does not match received txHash %08x", header.TxHash[:4], txHash[:4])
+		return false
+	}
+	uncleHash := types.CalcUncleHash(body.Uncles)
+	if header.UncleHash != uncleHash {
+		glog.V(access.LogLevel).Infof("ODR: header.UncleHash %08x does not match received uncleHash %08x", header.UncleHash[:4], uncleHash[:4])
+		return false
+	}
+	data, err := rlp.EncodeToBytes(body)
+	if err != nil {
+		glog.V(access.LogLevel).Infof("ODR: body RLP encode error: %v", err)
+		return false
+	}
+	self.rlp = data
+	glog.V(access.LogLevel).Infof("ODR: validation successful")
+	return true
+}
+
+// DbGet tries to retrieve requested data from the local database, returns
+// true and stores results in memory if successful
+// (implementation of access.ObjectAccess)
+func (self *BlockAccess) DbGet() bool {
+	self.rlp, _ = self.db.Get(append(append(blockPrefix, self.blockHash[:]...), bodySuffix...))
+	glog.V(access.LogLevel).Infof("ODR: get body %08x  len = %d", self.blockHash[:4], len(self.rlp))
+	return len(self.rlp) != 0
+}
+
+// DbPut stores the results of a successful request in the local database
+// (implementation of access.ObjectAccess)
+func (self *BlockAccess) DbPut() {
+	self.db.Put(append(append(blockPrefix, self.blockHash[:]...), bodySuffix...), self.rlp)
+	glog.V(access.LogLevel).Infof("ODR: put body %08x  len = %d", self.blockHash[:4], len(self.rlp))
+}
+
+// ReceiptsAccess is the ODR request type for block receipts by block hash
+type ReceiptsAccess struct {
+	access.ObjectAccess
+	db               ethdb.Database
+	blockHash        common.Hash
+	receipts         types.Receipts
+	getHeader        getHeaderFn
+	putReceipts      putReceiptsFn
+	putBlockReceipts putBlockReceiptsFn
+}
+
+type putReceiptsFn func(db ethdb.Database, receipts types.Receipts) error
+type putBlockReceiptsFn func(db ethdb.Database, hash common.Hash, receipts types.Receipts) error
+
+// NewReceiptsAccess creates a new ReceiptsAccess request
+func NewReceiptsAccess(db ethdb.Database, blockHash common.Hash, getHeader getHeaderFn, putReceipts putReceiptsFn, putBlockReceipts putBlockReceiptsFn) *ReceiptsAccess {
+	return &ReceiptsAccess{db: db, blockHash: blockHash, getHeader: getHeader, putReceipts: putReceipts, putBlockReceipts: putBlockReceipts}
+}
+
+// GetReceipts returns the block receipts stored in memory after a successful request
+func (self *ReceiptsAccess) GetReceipts() types.Receipts {
+	return self.receipts
+}
+
+// Request sends an ODR request to the LES network (implementation of access.ObjectAccess)
+func (self *ReceiptsAccess) Request(peer *access.Peer) error {
+	glog.V(access.LogLevel).Infof("ODR: requesting receipts for block %08x from peer %v", self.blockHash[:4], peer.Id())
+	return peer.GetReceipts([]common.Hash{self.blockHash})
+}
+
+// Valid processes an ODR request reply message from the LES network
+// returns true and stores results in memory if the message was a valid reply
+// to the request (implementation of access.ObjectAccess)
+func (self *ReceiptsAccess) Valid(msg *access.Msg) bool {
+	glog.V(access.LogLevel).Infof("ODR: validating receipts for block %08x", self.blockHash[:4])
+	if msg.MsgType != access.MsgReceipts {
+		glog.V(access.LogLevel).Infof("ODR: invalid message type")
+		return false
+	}
+	receipts := msg.Obj.([]types.Receipts)
+	if len(receipts) != 1 {
+		glog.V(access.LogLevel).Infof("ODR: invalid number of entries: %d", len(receipts))
+		return false
+	}
+	hash := types.DeriveSha(receipts[0])
+	header := self.getHeader(self.db, self.blockHash)
+	if header == nil {
+		glog.V(access.LogLevel).Infof("ODR: header not found for block %08x", self.blockHash[:4])
+		return false
+	}
+	if !bytes.Equal(header.ReceiptHash[:], hash[:]) {
+		glog.V(access.LogLevel).Infof("ODR: header receipts hash %08x does not match calculated RLP hash %08x", header.ReceiptHash[:4], hash[:4])
+		return false
+	}
+	self.receipts = receipts[0]
+	glog.V(access.LogLevel).Infof("ODR: validation successful")
+	return true
+}
+
+// DbGet tries to retrieve requested data from the local database, returns
+// true and stores results in memory if successful
+// (implementation of access.ObjectAccess)
+func (self *ReceiptsAccess) DbGet() bool {
+	data, _ := self.db.Get(append(blockReceiptsPre, self.blockHash[:]...))
+	if len(data) == 0 {
+		return false
+	}
+	rs := []*types.ReceiptForStorage{}
+	if err := rlp.DecodeBytes(data, &rs); err != nil {
+		glog.V(logger.Error).Infof("invalid receipt array RLP for hash %x: %v", self.blockHash, err)
+		return false
+	}
+	self.receipts = make(types.Receipts, len(rs))
+	for i, receipt := range rs {
+		self.receipts[i] = (*types.Receipt)(receipt)
+	}
+	return true
+}
+
+// DbPut stores the results of a successful request in the local database
+// (implementation of access.ObjectAccess)
+func (self *ReceiptsAccess) DbPut() {
+	self.putBlockReceipts(self.db, self.blockHash, self.receipts)
+	self.putReceipts(self.db, self.receipts)
+}

core/requests/trie_access.go

@@ -0,0 +1,200 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package state provides a caching layer atop the Ethereum state trie.
+package requests
+
+import (
+	"bytes"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/core/access"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/trie"
+	"golang.org/x/net/context"
+)
+
+// TrieAccess implements trie.OdrAccess, providing database/network access for
+// a trie identified by root hash
+type TrieAccess struct {
+	trie.OdrAccess
+	ca     *access.ChainAccess
+	root   common.Hash
+	trieDb trie.Database
+}
+
+// NewTrieAccess creates a new TrieAccess
+func NewTrieAccess(ca *access.ChainAccess, root common.Hash, trieDb trie.Database) *TrieAccess {
+	return &TrieAccess{
+		ca:     ca,
+		root:   root,
+		trieDb: trieDb,
+	}
+}
+
+// RetrieveKey retrieves a single key, returns true and stores nodes in local
+// database if successful
+func (self *TrieAccess) RetrieveKey(ctx context.Context, key []byte) bool {
+	//fmt.Println("request trie %v key %v", self.root, key)
+	r := NewTrieEntryAccess(self.root, self.trieDb, key)
+	return self.ca.Retrieve(ctx, r) == nil
+}
+
+// OdrEnabled returns true if this TrieAccess is capable of doing network requests
+func (self *TrieAccess) OdrEnabled() bool {
+	return self.ca.OdrEnabled()
+}
+
+// TrieEntryAccess is the ODR request type for state/storage trie entries
+type TrieEntryAccess struct {
+	access.ObjectAccess
+	root       common.Hash
+	trieDb     trie.Database
+	key, value []byte
+	proof      trie.MerkleProof
+	skipLevels int // set by DbGet() if unsuccessful
+}
+
+// NewTrieEntryAccess creates a new TrieEntryAccess request
+func NewTrieEntryAccess(root common.Hash, trieDb trie.Database, key []byte) *TrieEntryAccess {
+	return &TrieEntryAccess{root: root, trieDb: trieDb, key: key}
+}
+
+// Request sends an ODR request to the LES network (implementation of access.ObjectAccess)
+func (self *TrieEntryAccess) Request(peer *access.Peer) error {
+	glog.V(access.LogLevel).Infof("ODR: requesting trie root %08x key %08x from peer %v", self.root[:4], self.key[:4], peer.Id())
+	req := &access.ProofReq{
+		Root: self.root,
+		Key:  self.key,
+	}
+	return peer.GetProofs([]*access.ProofReq{req})
+}
+
+// Valid processes an ODR request reply message from the LES network
+// returns true and stores results in memory if the message was a valid reply
+// to the request (implementation of access.ObjectAccess)
+func (self *TrieEntryAccess) Valid(msg *access.Msg) bool {
+	glog.V(access.LogLevel).Infof("ODR: validating trie root %08x key %08x", self.root[:4], self.key[:4])
+
+	if msg.MsgType != access.MsgProofs {
+		glog.V(access.LogLevel).Infof("ODR: invalid message type")
+		return false
+	}
+	proofs := msg.Obj.([]trie.MerkleProof)
+	if len(proofs) != 1 {
+		glog.V(access.LogLevel).Infof("ODR: invalid number of entries: %d", len(proofs))
+		return false
+	}
+	value, err := trie.VerifyProof(self.root, self.key, proofs[0])
+	if err != nil {
+		glog.V(access.LogLevel).Infof("ODR: merkle proof verification error: %v", err)
+		return false
+	}
+	self.proof = proofs[0]
+	self.value = value
+	glog.V(access.LogLevel).Infof("ODR: validation successful")
+	return true
+}
+
+// DbGet tries to retrieve requested data from the local database, returns
+// true and stores results in memory if successful
+// (implementation of access.ObjectAccess)
+func (self *TrieEntryAccess) DbGet() bool {
+	return false // not used
+}
+
+// DbPut stores the results of a successful request in the local database
+// (implementation of access.ObjectAccess)
+func (self *TrieEntryAccess) DbPut() {
+	trie.StoreProof(self.trieDb, self.proof)
+}
+
+// NodeDataBlockAccess is the ODR request type for node data (used for retrieving contract code)
+type NodeDataAccess struct {
+	access.ObjectAccess
+	db   ethdb.Database
+	hash common.Hash
+	data []byte
+}
+
+// NewNodeDataAccess creates a new NodeDataAccess request
+func NewNodeDataAccess(db ethdb.Database, hash common.Hash) *NodeDataAccess {
+	return &NodeDataAccess{db: db, hash: hash}
+}
+
+// Request sends an ODR request to the LES network (implementation of access.ObjectAccess)
+func (self *NodeDataAccess) Request(peer *access.Peer) error {
+	glog.V(access.LogLevel).Infof("ODR: requesting node data for hash %08x from peer %v", self.hash[:4], peer.Id())
+	return peer.GetNodeData([]common.Hash{self.hash})
+}
+
+// Valid processes an ODR request reply message from the LES network
+// returns true and stores results in memory if the message was a valid reply
+// to the request (implementation of access.ObjectAccess)
+func (self *NodeDataAccess) Valid(msg *access.Msg) bool {
+	glog.V(access.LogLevel).Infof("ODR: validating node data for hash %08x", self.hash[:4])
+	if msg.MsgType != access.MsgNodeData {
+		glog.V(access.LogLevel).Infof("ODR: invalid message type")
+		return false
+	}
+	reply := msg.Obj.([][]byte)
+	if len(reply) != 1 {
+		glog.V(access.LogLevel).Infof("ODR: invalid number of entries: %d", len(reply))
+		return false
+	}
+	data := reply[0]
+	hash := crypto.Sha3Hash(data)
+	if bytes.Compare(self.hash[:], hash[:]) != 0 {
+		glog.V(access.LogLevel).Infof("ODR: requested hash %08x does not match received data hash %08x", self.hash[:4], hash[:4])
+		return false
+	}
+	self.data = data
+	glog.V(access.LogLevel).Infof("ODR: validation successful")
+	return true
+}
+
+// DbGet tries to retrieve requested data from the local database, returns
+// true and stores results in memory if successful
+// (implementation of access.ObjectAccess)
+func (self *NodeDataAccess) DbGet() bool {
+	data, _ := self.db.Get(self.hash[:])
+	if len(data) == 0 {
+		return false
+	}
+	self.data = data
+	return true
+}
+
+// DbPut stores the results of a successful request in the local database
+// (implementation of access.ObjectAccess)
+func (self *NodeDataAccess) DbPut() {
+	self.db.Put(self.hash[:], self.data)
+}
+
+var sha3_nil = sha3.NewKeccak256().Sum(nil)
+
+func RetrieveNodeData(ctx context.Context, ca *access.ChainAccess, hash common.Hash) []byte {
+	//fmt.Println("request node data %v", hash)
+	if bytes.Compare(hash[:], sha3_nil) == 0 {
+		return nil
+	}
+	r := NewNodeDataAccess(ca.Db(), hash)
+	ca.Retrieve(ctx, r)
+	return r.data
+}

core/state/dump.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 )
 
 type Account struct {
@@ -45,7 +46,7 @@ func (self *StateDB) RawDump() World {
 	it := self.trie.Iterator()
 	for it.Next() {
 		addr := self.trie.GetKey(it.Key)
-		stateObject := NewStateObjectFromBytes(common.BytesToAddress(addr), it.Value, self.db)
+		stateObject := NewStateObjectFromBytes(access.NoOdr, common.BytesToAddress(addr), it.Value, self.ca)
 
 		account := Account{Balance: stateObject.balance.String(), Nonce: stateObject.nonce, Root: common.Bytes2Hex(stateObject.Root()), CodeHash: common.Bytes2Hex(stateObject.codeHash)}
 		account.Storage = make(map[string]string)

core/state/managed_state_test.go

@@ -20,6 +20,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/ethdb"
 )
 
@@ -27,7 +28,7 @@ var addr = common.BytesToAddress([]byte("test"))
 
 func create() (*ManagedState, *account) {
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := New(common.Hash{}, db)
+	statedb, _ := New(common.Hash{}, access.NewDbChainAccess(db))
 	ms := ManageState(statedb)
 	so := &StateObject{address: addr, nonce: 100}
 	ms.StateDB.stateObjects[addr.Str()] = so

core/state/state_object.go

@@ -22,12 +22,14 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
+	"github.com/ethereum/go-ethereum/core/requests"
 	"github.com/ethereum/go-ethereum/crypto"
-	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
+	"golang.org/x/net/context"
 )
 
 type Code []byte
@@ -57,7 +59,8 @@ func (self Storage) Copy() Storage {
 
 type StateObject struct {
 	// State database for storing state changes
-	db   ethdb.Database
+	ca   *access.ChainAccess
+	ctx context.Context
 	trie *trie.SecureTrie
 
 	// Address belonging to this account
@@ -83,14 +86,14 @@ type StateObject struct {
 	dirty   bool
 }
 
-func NewStateObject(address common.Address, db ethdb.Database) *StateObject {
+func NewStateObject(ctx context.Context, address common.Address, ca *access.ChainAccess) *StateObject {
-	object := &StateObject{db: db, address: address, balance: new(big.Int), dirty: true}
+	object := &StateObject{ca: ca, ctx: ctx, address: address, balance: new(big.Int), dirty: true}
-	object.trie, _ = trie.NewSecure(common.Hash{}, db)
+	object.trie, _ = trie.NewSecure(common.Hash{}, ca.Db())
 	object.storage = make(Storage)
 	return object
 }
 
-func NewStateObjectFromBytes(address common.Address, data []byte, db ethdb.Database) *StateObject {
+func NewStateObjectFromBytes(ctx context.Context, address common.Address, data []byte, ca *access.ChainAccess) *StateObject {
 	var extobject struct {
 		Nonce    uint64
 		Balance  *big.Int
@@ -102,20 +105,20 @@ func NewStateObjectFromBytes(address common.Address, data []byte, db ethdb.Datab
 		glog.Errorf("can't decode state object %x: %v", address, err)
 		return nil
 	}
-	trie, err := trie.NewSecure(extobject.Root, db)
+	trie, err := trie.NewSecureOdr(ctx, extobject.Root, ca.Db(), requests.NewTrieAccess(ca, extobject.Root, ca.Db()))
 	if err != nil {
 		// TODO: bubble this up or panic
 		glog.Errorf("can't create account trie with root %x: %v", extobject.Root[:], err)
 		return nil
 	}
 
-	object := &StateObject{address: address, db: db}
+	object := &StateObject{address: address, ca: ca, ctx: ctx}
 	object.nonce = extobject.Nonce
 	object.balance = extobject.Balance
 	object.codeHash = extobject.CodeHash
 	object.trie = trie
 	object.storage = make(map[string]common.Hash)
-	object.code, _ = db.Get(extobject.CodeHash)
+	object.code = requests.RetrieveNodeData(ctx, ca, common.BytesToHash(extobject.CodeHash))
 	return object
 }
 
@@ -130,7 +133,8 @@ func (self *StateObject) MarkForDeletion() {
 
 func (c *StateObject) getAddr(addr common.Hash) common.Hash {
 	var ret []byte
-	rlp.DecodeBytes(c.trie.Get(addr[:]), &ret)
+	value := c.trie.Get(addr[:])
+	rlp.DecodeBytes(value, &ret)
 	return common.BytesToHash(ret)
 }
 
@@ -205,12 +209,22 @@ func (c *StateObject) St() Storage {
 // Return the gas back to the origin. Used by the Virtual machine or Closures
 func (c *StateObject) ReturnGas(gas, price *big.Int) {}
 
+// Copy creates a copy of the state object
 func (self *StateObject) Copy() *StateObject {
-	stateObject := NewStateObject(self.Address(), self.db)
+	return self.CopyOdr(access.NoOdr)
+}
+
+// CopyOdr creates a copy of the state object with ODR option
+func (self *StateObject) CopyOdr(ctx context.Context) *StateObject {
+	stateObject := NewStateObject(ctx, self.Address(), self.ca)
 	stateObject.balance.Set(self.balance)
 	stateObject.codeHash = common.CopyBytes(self.codeHash)
 	stateObject.nonce = self.nonce
+	if access.IsOdrContext(ctx) {
+		stateObject.trie = self.trie.CopySecureWithOdr(ctx, requests.NewTrieAccess(self.ca, common.BytesToHash(self.trie.Root()), self.ca.Db()))
+	} else {
 		stateObject.trie = self.trie
+	}
 	stateObject.code = common.CopyBytes(self.code)
 	stateObject.initCode = common.CopyBytes(self.initCode)
 	stateObject.storage = self.storage.Copy()

core/state/state_test.go

@@ -24,6 +24,7 @@ import (
 	checker "gopkg.in/check.v1"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/ethdb"
 )
 
@@ -77,12 +78,12 @@ func (s *StateSuite) TestDump(c *checker.C) {
 
 func (s *StateSuite) SetUpTest(c *checker.C) {
 	db, _ := ethdb.NewMemDatabase()
-	s.state, _ = New(common.Hash{}, db)
+	s.state, _ = New(common.Hash{}, access.NewDbChainAccess(db))
 }
 
 func TestNull(t *testing.T) {
 	db, _ := ethdb.NewMemDatabase()
-	state, _ := New(common.Hash{}, db)
+	state, _ := New(common.Hash{}, access.NewDbChainAccess(db))
 
 	address := common.HexToAddress("0x823140710bf13990e4500136726d8b55")
 	state.CreateAccount(address)
@@ -122,7 +123,7 @@ func (s *StateSuite) TestSnapshot(c *checker.C) {
 // printing/logging in tests (-check.vv does not work)
 func TestSnapshot2(t *testing.T) {
 	db, _ := ethdb.NewMemDatabase()
-	state, _ := New(common.Hash{}, db)
+	state, _ := New(common.Hash{}, access.NewDbChainAccess(db))
 
 	stateobjaddr0 := toAddr([]byte("so0"))
 	stateobjaddr1 := toAddr([]byte("so1"))

core/state/statedb.go

@@ -22,10 +22,13 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/core/access"
+	"github.com/ethereum/go-ethereum/core/requests"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/trie"
+	"golang.org/x/net/context"
 )
 
 // The starting nonce determines the default nonce when new accounts are being
@@ -38,8 +41,9 @@ var StartingNonce uint64
 // * Contracts
 // * Accounts
 type StateDB struct {
-	db   ethdb.Database
+	ca   *access.ChainAccess
 	trie *trie.SecureTrie
+	ctx context.Context
 
 	stateObjects map[string]*StateObject
 
@@ -51,22 +55,33 @@ type StateDB struct {
 	logSize      uint
 }
 
-// Create a new state from a given trie
+// New creates a new state from a given trie
-func New(root common.Hash, db ethdb.Database) (*StateDB, error) {
+func New(root common.Hash, ca *access.ChainAccess) (*StateDB, error) {
-	tr, err := trie.NewSecure(root, db)
+	return NewOdr(access.NoOdr, root, ca)
+}
+
+// NewOdr creates a new state from a given trie with ODR option
+func NewOdr(ctx context.Context, root common.Hash, ca *access.ChainAccess) (*StateDB, error) {
+	tr, err := trie.NewSecureOdr(ctx, root, ca.Db(), requests.NewTrieAccess(ca, root, ca.Db()))
 	if err != nil {
 		glog.Errorf("can't create state trie with root %x: %v", root[:], err)
 		return nil, err
 	}
 	return &StateDB{
-		db:           db,
+		ca:           ca,
 		trie:         tr,
+		ctx:		  ctx,
 		stateObjects: make(map[string]*StateObject),
 		refund:       new(big.Int),
 		logs:         make(map[common.Hash]vm.Logs),
 	}, nil
 }
 
+// Ctx returns the ODR context of the state
+func (self *StateDB) Ctx() context.Context {
+	return self.ctx
+}
+
 func (self *StateDB) StartRecord(thash, bhash common.Hash, ti int) {
 	self.thash = thash
 	self.bhash = bhash
@@ -208,7 +223,7 @@ func (self *StateDB) UpdateStateObject(stateObject *StateObject) {
 	//addr := stateObject.Address()
 
 	if len(stateObject.CodeHash()) > 0 {
-		self.db.Put(stateObject.CodeHash(), stateObject.code)
+		self.ca.Db().Put(stateObject.CodeHash(), stateObject.code)
 	}
 	addr := stateObject.Address()
 	self.trie.Update(addr[:], stateObject.RlpEncode())
@@ -220,7 +235,6 @@ func (self *StateDB) DeleteStateObject(stateObject *StateObject) {
 
 	addr := stateObject.Address()
 	self.trie.Delete(addr[:])
-	//delete(self.stateObjects, addr.Str())
 }
 
 // Retrieve a state object given my the address. Nil if not found
@@ -239,7 +253,7 @@ func (self *StateDB) GetStateObject(addr common.Address) (stateObject *StateObje
 		return nil
 	}
 
-	stateObject = NewStateObjectFromBytes(addr, []byte(data), self.db)
+	stateObject = NewStateObjectFromBytes(self.ctx, addr, []byte(data), self.ca)
 	self.SetStateObject(stateObject)
 
 	return stateObject
@@ -265,7 +279,7 @@ func (self *StateDB) newStateObject(addr common.Address) *StateObject {
 		glog.Infof("(+) %x\n", addr)
 	}
 
-	stateObject := NewStateObject(addr, self.db)
+	stateObject := NewStateObject(self.ctx, addr, self.ca)
 	stateObject.SetNonce(StartingNonce)
 	self.stateObjects[addr.Str()] = stateObject
 
@@ -295,12 +309,27 @@ func (self *StateDB) CreateAccount(addr common.Address) vm.Account {
 // Setting, copying of the state methods
 //
 
+// CopyWithCtx creates a copy of the state, keeping the original ODR context
+func (self *StateDB) CopyWithCtx() *StateDB {
+	return self.CopyOdr(self.ctx)
+}
+
+// Copy creates a copy of the state with no ODR option
 func (self *StateDB) Copy() *StateDB {
+	return self.CopyOdr(access.NoOdr)
+}
+
+// CopyOdr creates a copy of the state with a new ODR context
+func (self *StateDB) CopyOdr(ctx context.Context) *StateDB {
 	// ignore error - we assume state-to-be-copied always exists
-	state, _ := New(common.Hash{}, self.db)
+	state, _ := NewOdr(ctx, common.Hash{}, self.ca)
+	if access.IsOdrContext(ctx) {
+		state.trie = self.trie.CopySecureWithOdr(ctx, requests.NewTrieAccess(self.ca, common.BytesToHash(self.trie.Root()), self.ca.Db()))
+	} else {
 		state.trie = self.trie
+	}
 	for k, stateObject := range self.stateObjects {
-		state.stateObjects[k] = stateObject.Copy()
+		state.stateObjects[k] = stateObject.CopyOdr(ctx)
 	}
 
 	state.refund.Set(self.refund)
@@ -348,14 +377,14 @@ func (s *StateDB) IntermediateRoot() common.Hash {
 
 // Commit commits all state changes to the database.
 func (s *StateDB) Commit() (root common.Hash, err error) {
-	return s.commit(s.db)
+	return s.commit(s.ca.Db())
 }
 
 // CommitBatch commits all state changes to a write batch but does not
 // execute the batch. It is used to validate state changes against
 // the root hash stored in a block.
 func (s *StateDB) CommitBatch() (root common.Hash, batch ethdb.Batch) {
-	batch = s.db.NewBatch()
+	batch = s.ca.Db().NewBatch()
 	root, _ = s.commit(batch)
 	return root, batch
 }

core/state/sync_test.go

@@ -22,6 +22,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/trie"
 )
@@ -38,7 +39,7 @@ type testAccount struct {
 func makeTestState() (ethdb.Database, common.Hash, []*testAccount) {
 	// Create an empty state
 	db, _ := ethdb.NewMemDatabase()
-	state, _ := New(common.Hash{}, db)
+	state, _ := New(common.Hash{}, access.NewDbChainAccess(db))
 
 	// Fill it with some arbitrary data
 	accounts := []*testAccount{}
@@ -68,7 +69,7 @@ func makeTestState() (ethdb.Database, common.Hash, []*testAccount) {
 // checkStateAccounts cross references a reconstructed state with an expected
 // account array.
 func checkStateAccounts(t *testing.T, db ethdb.Database, root common.Hash, accounts []*testAccount) {
-	state, _ := New(root, db)
+	state, _ := New(root, access.NewDbChainAccess(db))
 	for i, acc := range accounts {
 
 		if balance := state.GetBalance(acc.address); balance.Cmp(acc.balance) != 0 {

core/transaction_pool_test.go

@@ -22,6 +22,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -36,7 +37,7 @@ func transaction(nonce uint64, gaslimit *big.Int, key *ecdsa.PrivateKey) *types.
 
 func setupTxPool() (*TxPool, *ecdsa.PrivateKey) {
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
+	statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 
 	var m event.TypeMux
 	key, _ := crypto.GenerateKey()
@@ -163,7 +164,7 @@ func TestTransactionChainFork(t *testing.T) {
 	addr := crypto.PubkeyToAddress(key.PublicKey)
 	resetState := func() {
 		db, _ := ethdb.NewMemDatabase()
-		statedb, _ := state.New(common.Hash{}, db)
+		statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 		pool.currentState = func() (*state.StateDB, error) { return statedb, nil }
 		currentState, _ := pool.currentState()
 		currentState.AddBalance(addr, big.NewInt(100000000000000))
@@ -189,7 +190,7 @@ func TestTransactionDoubleNonce(t *testing.T) {
 	addr := crypto.PubkeyToAddress(key.PublicKey)
 	resetState := func() {
 		db, _ := ethdb.NewMemDatabase()
-		statedb, _ := state.New(common.Hash{}, db)
+		statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 		pool.currentState = func() (*state.StateDB, error) { return statedb, nil }
 		currentState, _ := pool.currentState()
 		currentState.AddBalance(addr, big.NewInt(100000000000000))

core/transaction_util.go

@@ -20,17 +20,20 @@ import (
 	"fmt"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
+	"github.com/ethereum/go-ethereum/core/requests"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/syndtr/goleveldb/leveldb"
+	"golang.org/x/net/context"
 )
 
 var (
-	receiptsPre      = []byte("receipts-")
 	blockReceiptsPre = []byte("receipts-block-")
+	receiptsPre      = []byte("receipts-")
 )
 
 // PutTransactions stores the transactions in the given database
@@ -119,8 +122,8 @@ func DeleteReceipt(db ethdb.Database, txHash common.Hash) {
 }
 
 // GetReceipt returns a receipt by hash
-func GetReceipt(db ethdb.Database, txHash common.Hash) *types.Receipt {
+func GetReceipt(ca *access.ChainAccess, txHash common.Hash) *types.Receipt {
-	data, _ := db.Get(append(receiptsPre, txHash[:]...))
+	data, _ := ca.Db().Get(append(receiptsPre, txHash[:]...))
 	if len(data) == 0 {
 		return nil
 	}
@@ -134,21 +137,16 @@ func GetReceipt(db ethdb.Database, txHash common.Hash) *types.Receipt {
 
 // GetBlockReceipts returns the receipts generated by the transactions
 // included in block's given hash.
-func GetBlockReceipts(db ethdb.Database, hash common.Hash) types.Receipts {
+func GetBlockReceipts(ca *access.ChainAccess, hash common.Hash) types.Receipts {
-	data, _ := db.Get(append(blockReceiptsPre, hash[:]...))
+	return GetBlockReceiptsOdr(access.NoOdr, ca, hash)
-	if len(data) == 0 {
-		return nil
 }
-	rs := []*types.ReceiptForStorage{}
+
-	if err := rlp.DecodeBytes(data, &rs); err != nil {
+// GetBlockReceiptsOdr returns the receipts generated by the transactions
-		glog.V(logger.Error).Infof("invalid receipt array RLP for hash %x: %v", hash, err)
+// included in block's given hash from the database or network.
-		return nil
+func GetBlockReceiptsOdr(ctx context.Context, ca *access.ChainAccess, hash common.Hash) types.Receipts {
-	}
+	r := requests.NewReceiptsAccess(ca.Db(), hash, GetHeader, PutReceipts, PutBlockReceipts)
-	receipts := make(types.Receipts, len(rs))
+	ca.Retrieve(ctx, r)
-	for i, receipt := range rs {
+	return r.GetReceipts()
-		receipts[i] = (*types.Receipt)(receipt)
-	}
-	return receipts
 }
 
 // PutBlockReceipts stores the block's transactions associated receipts

core/vm_env.go

@@ -76,7 +76,7 @@ func (self *VMEnv) CanTransfer(from common.Address, balance *big.Int) bool {
 }
 
 func (self *VMEnv) MakeSnapshot() vm.Database {
-	return self.state.Copy()
+	return self.state.CopyWithCtx()
 }
 
 func (self *VMEnv) SetSnapshot(copy vm.Database) {

eth/backend.go

@@ -37,6 +37,7 @@ import (
 	"github.com/ethereum/go-ethereum/common/compiler"
 	"github.com/ethereum/go-ethereum/common/httpclient"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -231,6 +232,8 @@ type Ethereum struct {
 	chainDb ethdb.Database // Block chain database
 	dappDb  ethdb.Database // Dapp database
 
+	chainAccess *access.ChainAccess // blockchain access layer
+
 	//*** SERVICES ***
 	// State manager for processing new blocks and managing the over all states
 	blockProcessor  *core.BlockProcessor
@@ -297,10 +300,10 @@ func New(config *Config) (*Ethereum, error) {
 	if err := upgradeChainDatabase(chainDb); err != nil {
 		return nil, err
 	}
-	if err := addMipmapBloomBins(chainDb); err != nil {
+	chainAccess := access.NewChainAccess(chainDb, false)
+	if err := addMipmapBloomBins(chainAccess); err != nil {
 		return nil, err
 	}
-
 	dappDb, err := newdb(filepath.Join(config.DataDir, "dapp"))
 	if err != nil {
 		if errno, ok := err.(syscall.Errno); ok && datadirInUseErrnos[uint(errno)] {
@@ -366,6 +369,7 @@ func New(config *Config) (*Ethereum, error) {
 	eth := &Ethereum{
 		shutdownChan:            make(chan bool),
 		chainDb:                 chainDb,
+		chainAccess:             chainAccess,
 		dappDb:                  dappDb,
 		eventMux:                &event.TypeMux{},
 		accountManager:          config.AccountManager,
@@ -397,7 +401,7 @@ func New(config *Config) (*Ethereum, error) {
 		eth.pow = ethash.New()
 	}
 	//genesis := core.GenesisBlock(uint64(config.GenesisNonce), stateDb)
-	eth.blockchain, err = core.NewBlockChain(chainDb, eth.pow, eth.EventMux())
+	eth.blockchain, err = core.NewBlockChain(chainAccess, eth.pow, eth.EventMux())
 	if err != nil {
 		if err == core.ErrNoGenesis {
 			return nil, fmt.Errorf(`Genesis block not found. Please supply a genesis block with the "--genesis /path/to/file" argument`)
@@ -407,11 +411,13 @@ func New(config *Config) (*Ethereum, error) {
 	newPool := core.NewTxPool(eth.EventMux(), eth.blockchain.State, eth.blockchain.GasLimit)
 	eth.txPool = newPool
 
-	eth.blockProcessor = core.NewBlockProcessor(chainDb, eth.pow, eth.blockchain, eth.EventMux())
+	eth.blockProcessor = core.NewBlockProcessor(chainAccess, eth.pow, eth.blockchain, eth.EventMux())
 	eth.blockchain.SetProcessor(eth.blockProcessor)
-	if eth.protocolManager, err = NewProtocolManager(config.FastSync, config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainDb); err != nil {
+
+	if eth.protocolManager, err = NewProtocolManager(config.FastSync, config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainAccess); err != nil {
 		return nil, err
 	}
+
 	eth.miner = miner.New(eth, eth.EventMux(), eth.pow)
 	eth.miner.SetGasPrice(config.GasPrice)
 	eth.miner.SetExtra(config.ExtraData)
@@ -493,6 +499,7 @@ func (s *Ethereum) TxPool() *core.TxPool                 { return s.txPool }
 func (s *Ethereum) Whisper() *whisper.Whisper            { return s.whisper }
 func (s *Ethereum) EventMux() *event.TypeMux             { return s.eventMux }
 func (s *Ethereum) ChainDb() ethdb.Database              { return s.chainDb }
+func (s *Ethereum) ChainAccess() *access.ChainAccess     { return s.chainAccess }
 func (s *Ethereum) DappDb() ethdb.Database               { return s.dappDb }
 func (s *Ethereum) IsListening() bool                    { return true } // Always listening
 func (s *Ethereum) PeerCount() int                       { return s.net.PeerCount() }
@@ -732,9 +739,10 @@ func upgradeChainDatabase(db ethdb.Database) error {
 	return nil
 }
 
-func addMipmapBloomBins(db ethdb.Database) (err error) {
+func addMipmapBloomBins(ca *access.ChainAccess) (err error) {
 	const mipmapVersion uint = 2
 
+	db := ca.Db()
 	// check if the version is set. We ignore data for now since there's
 	// only one version so we can easily ignore it for now
 	var data []byte
@@ -756,7 +764,7 @@ func addMipmapBloomBins(db ethdb.Database) (err error) {
 			return
 		}
 	}()
-	latestBlock := core.GetBlock(db, core.GetHeadBlockHash(db))
+	latestBlock := core.GetBlock(ca, core.GetHeadBlockHash(db))
 	if latestBlock == nil { // clean database
 		return
 	}
@@ -768,7 +776,7 @@ func addMipmapBloomBins(db ethdb.Database) (err error) {
 		if (hash == common.Hash{}) {
 			return fmt.Errorf("chain db corrupted. Could not find block %d.", i)
 		}
-		core.WriteMipmapBloom(db, i, core.GetBlockReceipts(db, hash))
+		core.WriteMipmapBloom(db, i, core.GetBlockReceipts(ca, hash))
 	}
 	glog.V(logger.Info).Infoln("upgrade completed in", time.Since(tstart))
 	return nil

eth/backend_test.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -50,7 +51,7 @@ func TestMipmapUpgrade(t *testing.T) {
 		}
 	}
 
-	err := addMipmapBloomBins(db)
+	err := addMipmapBloomBins(access.NewDbChainAccess(db))
 	if err != nil {
 		t.Fatal(err)
 	}

eth/downloader/downloader_test.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -682,7 +683,7 @@ func assertOwnForkedChain(t *testing.T, tester *downloadTester, common int, leng
 			index = len(tester.ownHashes) - lengths[len(lengths)-1] + int(tester.downloader.queue.fastSyncPivot)
 		}
 		if index > 0 {
-			if statedb, err := state.New(tester.ownHeaders[tester.ownHashes[index]].Root, tester.stateDb); statedb == nil || err != nil {
+			if statedb, err := state.New(tester.ownHeaders[tester.ownHashes[index]].Root, access.NewDbChainAccess(tester.stateDb)); statedb == nil || err != nil {
 				t.Fatalf("state reconstruction failed: %v", err)
 			}
 		}

eth/filters/filter.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -32,6 +33,7 @@ type AccountChange struct {
 
 // Filtering interface
 type Filter struct {
+	ca         *access.ChainAccess
 	db         ethdb.Database
 	begin, end int64
 	addresses  []common.Address
@@ -42,10 +44,15 @@ type Filter struct {
 	LogsCallback        func(vm.Logs)
 }
 
-// Create a new filter which uses a bloom filter on blocks to figure out whether a particular block
+// New creates a new filter which uses a bloom filter on blocks to figure out whether a particular block
 // is interesting or not.
-func New(db ethdb.Database) *Filter {
+func New(ca *access.ChainAccess) *Filter {
-	return &Filter{db: db}
+	return &Filter{ca: ca, db: ca.Db()}
+}
+
+// NewWithDb creates a filter with no ODR option
+func NewWithDb(db ethdb.Database) *Filter {
+	return &Filter{ca: access.NewDbChainAccess(db), db: db}
 }
 
 // Set the earliest and latest block for filtering.
@@ -69,7 +76,7 @@ func (self *Filter) SetTopics(topics [][]common.Hash) {
 
 // Run filters logs with the current parameters set
 func (self *Filter) Find() vm.Logs {
-	latestBlock := core.GetBlock(self.db, core.GetHeadBlockHash(self.db))
+	latestBlock := core.GetBlock(self.ca, core.GetHeadBlockHash(self.db))
 	var beginBlockNo uint64 = uint64(self.begin)
 	if self.begin == -1 {
 		beginBlockNo = latestBlock.NumberU64()
@@ -124,7 +131,7 @@ func (self *Filter) getLogs(start, end uint64) (logs vm.Logs) {
 	for i := start; i <= end; i++ {
 		hash := core.GetCanonicalHash(self.db, i)
 		if hash != (common.Hash{}) {
-			block = core.GetBlock(self.db, hash)
+			block = core.GetBlock(self.ca, hash)
 		} else { // block not found
 			return logs
 		}
@@ -134,7 +141,7 @@ func (self *Filter) getLogs(start, end uint64) (logs vm.Logs) {
 		if self.bloomFilter(block) {
 			// Get the logs of the block
 			var (
-				receipts   = core.GetBlockReceipts(self.db, block.Hash())
+				receipts   = core.GetBlockReceipts(self.ca, block.Hash())
 				unfiltered vm.Logs
 			)
 			for _, receipt := range receipts {
@@ -142,6 +149,7 @@ func (self *Filter) getLogs(start, end uint64) (logs vm.Logs) {
 			}
 			logs = append(logs, self.FilterLogs(unfiltered)...)
 		}
+		block = core.GetBlock(self.ca, block.ParentHash())
 	}
 
 	return logs

eth/filters/filter_test.go

@@ -84,7 +84,7 @@ func BenchmarkMipmaps(b *testing.B) {
 	}
 	b.ResetTimer()
 
-	filter := New(db)
+	filter := NewWithDb(db)
 	filter.SetAddresses([]common.Address{addr1, addr2, addr3, addr4})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
@@ -185,7 +185,7 @@ func TestFilters(t *testing.T) {
 		}
 	}
 
-	filter := New(db)
+	filter := NewWithDb(db)
 	filter.SetAddresses([]common.Address{addr})
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash1, hash2, hash3, hash4}})
 	filter.SetBeginBlock(0)
@@ -196,7 +196,7 @@ func TestFilters(t *testing.T) {
 		t.Error("expected 4 log, got", len(logs))
 	}
 
-	filter = New(db)
+	filter = NewWithDb(db)
 	filter.SetAddresses([]common.Address{addr})
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash3}})
 	filter.SetBeginBlock(900)
@@ -209,7 +209,7 @@ func TestFilters(t *testing.T) {
 		t.Errorf("expected log[0].Topics[0] to be %x, got %x", hash3, logs[0].Topics[0])
 	}
 
-	filter = New(db)
+	filter = NewWithDb(db)
 	filter.SetAddresses([]common.Address{addr})
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash3}})
 	filter.SetBeginBlock(990)
@@ -222,7 +222,7 @@ func TestFilters(t *testing.T) {
 		t.Errorf("expected log[0].Topics[0] to be %x, got %x", hash3, logs[0].Topics[0])
 	}
 
-	filter = New(db)
+	filter = NewWithDb(db)
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash1, hash2}})
 	filter.SetBeginBlock(1)
 	filter.SetEndBlock(10)
@@ -233,7 +233,7 @@ func TestFilters(t *testing.T) {
 	}
 
 	failHash := common.BytesToHash([]byte("fail"))
-	filter = New(db)
+	filter = NewWithDb(db)
 	filter.SetTopics([][]common.Hash{[]common.Hash{failHash}})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
@@ -244,7 +244,7 @@ func TestFilters(t *testing.T) {
 	}
 
 	failAddr := common.BytesToAddress([]byte("failmenow"))
-	filter = New(db)
+	filter = NewWithDb(db)
 	filter.SetAddresses([]common.Address{failAddr})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
@@ -254,7 +254,7 @@ func TestFilters(t *testing.T) {
 		t.Error("expected 0 log, got", len(logs))
 	}
 
-	filter = New(db)
+	filter = NewWithDb(db)
 	filter.SetTopics([][]common.Hash{[]common.Hash{failHash}, []common.Hash{hash1}})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)

eth/handler.go

@@ -26,10 +26,10 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/eth/fetcher"
-	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
@@ -61,7 +61,7 @@ type ProtocolManager struct {
 	fastSync    bool
 	txpool      txPool
 	blockchain  *core.BlockChain
-	chaindb    ethdb.Database
+	chainAccess *access.ChainAccess
 
 	downloader *downloader.Downloader
 	fetcher    *fetcher.Fetcher
@@ -86,7 +86,7 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
-func NewProtocolManager(fastSync bool, networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, blockchain *core.BlockChain, chaindb ethdb.Database) (*ProtocolManager, error) {
+func NewProtocolManager(fastSync bool, networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, blockchain *core.BlockChain, ca *access.ChainAccess) (*ProtocolManager, error) {
 	// Figure out whether to allow fast sync or not
 	if fastSync && blockchain.CurrentBlock().NumberU64() > 0 {
 		glog.V(logger.Info).Infof("blockchain not empty, fast sync disabled")
@@ -99,7 +99,7 @@ func NewProtocolManager(fastSync bool, networkId int, mux *event.TypeMux, txpool
 		eventMux:    mux,
 		txpool:      txpool,
 		blockchain:  blockchain,
-		chaindb:    chaindb,
+		chainAccess: ca,
 		peers:       newPeerSet(),
 		newPeerCh:   make(chan *peer, 1),
 		txsyncCh:    make(chan *txsync),
@@ -109,7 +109,7 @@ func NewProtocolManager(fastSync bool, networkId int, mux *event.TypeMux, txpool
 	manager.SubProtocols = make([]p2p.Protocol, 0, len(ProtocolVersions))
 	for i, version := range ProtocolVersions {
 		// Skip protocol version if incompatible with the mode of operation
-		if fastSync && version < eth63 {
+		if manager.fastSync && version < eth63 {
 			continue
 		}
 		// Compatible; initialise the sub-protocol
@@ -137,9 +137,8 @@ func NewProtocolManager(fastSync bool, networkId int, mux *event.TypeMux, txpool
 	if len(manager.SubProtocols) == 0 {
 		return nil, errIncompatibleConfig
 	}
-	// Construct the different synchronisation mechanisms
+	manager.downloader = downloader.New(ca.Db(), manager.eventMux, blockchain.HasHeader, blockchain.HasBlock, blockchain.GetHeader,
-	manager.downloader = downloader.New(chaindb, manager.eventMux, blockchain.HasHeader, blockchain.HasBlock, blockchain.GetHeader, blockchain.GetBlock,
+		blockchain.GetBlock, blockchain.CurrentHeader, blockchain.CurrentBlock, blockchain.CurrentFastBlock, blockchain.FastSyncCommitHead, blockchain.GetTd,
-		blockchain.CurrentHeader, blockchain.CurrentBlock, blockchain.CurrentFastBlock, blockchain.FastSyncCommitHead, blockchain.GetTd,
 		blockchain.InsertHeaderChain, blockchain.InsertChain, blockchain.InsertReceiptChain, blockchain.Rollback, manager.removePeer)
 
 	validator := func(block *types.Block, parent *types.Block) error {
@@ -233,6 +232,7 @@ func (pm *ProtocolManager) handle(p *peer) error {
 		p.RequestHeadersByNumber, p.RequestBodies, p.RequestReceipts, p.RequestNodeData); err != nil {
 		return err
 	}
+
 	// Propagate existing transactions. new transactions appearing
 	// after this will be sent via broadcasts.
 	pm.syncTransactions(p)
@@ -517,7 +517,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 				return errResp(ErrDecode, "msg %v: %v", msg, err)
 			}
 			// Retrieve the requested state entry, stopping if enough was found
-			if entry, err := pm.chaindb.Get(hash.Bytes()); err == nil {
+			if entry, err := pm.chainAccess.Db().Get(hash.Bytes()); err == nil {
 				data = append(data, entry)
 				bytes += len(entry)
 			}
@@ -555,7 +555,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 				return errResp(ErrDecode, "msg %v: %v", msg, err)
 			}
 			// Retrieve the requested block's receipts, skipping if unknown to us
-			results := core.GetBlockReceipts(pm.chaindb, hash)
+			results := core.GetBlockReceipts(pm.chainAccess, hash)
 			if results == nil {
 				if header := pm.blockchain.GetHeader(hash); header == nil || header.ReceiptHash != types.EmptyRootHash {
 					continue

eth/handler_test.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -35,7 +36,6 @@ func TestProtocolCompatibility(t *testing.T) {
 	// Try all available compatibility configs and check for errors
 	for i, tt := range tests {
 		ProtocolVersions = []uint{tt.version}
-
 		pm, err := newTestProtocolManager(tt.fastSync, 0, nil, nil)
 		if pm != nil {
 			defer pm.Stop()
@@ -365,7 +365,7 @@ func testGetBlockBodies(t *testing.T, protocol int) {
 	for i, tt := range tests {
 		// Collect the hashes to request, and the response to expect
 		hashes, seen := []common.Hash{}, make(map[int64]bool)
-		bodies := []*blockBody{}
+		bodies := []*types.Body{}
 
 		for j := 0; j < tt.random; j++ {
 			for {
@@ -376,7 +376,7 @@ func testGetBlockBodies(t *testing.T, protocol int) {
 					block := pm.blockchain.GetBlockByNumber(uint64(num))
 					hashes = append(hashes, block.Hash())
 					if len(bodies) < tt.expected {
-						bodies = append(bodies, &blockBody{Transactions: block.Transactions(), Uncles: block.Uncles()})
+						bodies = append(bodies, &types.Body{Transactions: block.Transactions(), Uncles: block.Uncles()})
 					}
 					break
 				}
@@ -386,7 +386,7 @@ func testGetBlockBodies(t *testing.T, protocol int) {
 			hashes = append(hashes, hash)
 			if tt.available[j] && len(bodies) < tt.expected {
 				block := pm.blockchain.GetBlock(hash)
-				bodies = append(bodies, &blockBody{Transactions: block.Transactions(), Uncles: block.Uncles()})
+				bodies = append(bodies, &types.Body{Transactions: block.Transactions(), Uncles: block.Uncles()})
 			}
 		}
 		// Send the hash request and verify the response
@@ -442,7 +442,7 @@ func testGetNodeData(t *testing.T, protocol int) {
 
 	// Fetch for now the entire chain db
 	hashes := []common.Hash{}
-	for _, key := range pm.chaindb.(*ethdb.MemDatabase).Keys() {
+	for _, key := range pm.chainAccess.Db().(*ethdb.MemDatabase).Keys() {
 		if len(key) == len(common.Hash{}) {
 			hashes = append(hashes, common.BytesToHash(key))
 		}
@@ -471,7 +471,7 @@ func testGetNodeData(t *testing.T, protocol int) {
 	}
 	accounts := []common.Address{testBankAddress, acc1Addr, acc2Addr}
 	for i := uint64(0); i <= pm.blockchain.CurrentBlock().NumberU64(); i++ {
-		trie, _ := state.New(pm.blockchain.GetBlockByNumber(i).Root(), statedb)
+		trie, _ := state.New(pm.blockchain.GetBlockByNumber(i).Root(), access.NewDbChainAccess(statedb))
 
 		for j, acc := range accounts {
 			state, _ := pm.blockchain.State()
@@ -537,7 +537,7 @@ func testGetReceipt(t *testing.T, protocol int) {
 		block := pm.blockchain.GetBlockByNumber(i)
 
 		hashes = append(hashes, block.Hash())
-		receipts = append(receipts, core.GetBlockReceipts(pm.chaindb, block.Hash()))
+		receipts = append(receipts, core.GetBlockReceipts(pm.chainAccess, block.Hash()))
 	}
 	// Send the hash request and verify the response
 	p2p.Send(peer.app, 0x0f, hashes)

eth/helper_test.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -33,16 +34,17 @@ func newTestProtocolManager(fastSync bool, blocks int, generator func(int, *core
 		evmux         = new(event.TypeMux)
 		pow           = new(core.FakePow)
 		db, _         = ethdb.NewMemDatabase()
+		ca            = access.NewDbChainAccess(db)
 		genesis       = core.WriteGenesisBlockForTesting(db, core.GenesisAccount{testBankAddress, testBankFunds})
-		blockchain, _ = core.NewBlockChain(db, pow, evmux)
+		blockchain, _ = core.NewBlockChain(ca, pow, evmux)
-		blockproc     = core.NewBlockProcessor(db, pow, blockchain, evmux)
+		blockproc     = core.NewBlockProcessor(ca, pow, blockchain, evmux)
 	)
 	blockchain.SetProcessor(blockproc)
 	chain, _ := core.GenerateChain(genesis, db, blocks, generator)
 	if _, err := blockchain.InsertChain(chain); err != nil {
 		panic(err)
 	}
-	pm, err := NewProtocolManager(fastSync, NetworkId, evmux, &testTxPool{added: newtx}, pow, blockchain, db)
+	pm, err := NewProtocolManager(fastSync, NetworkId, evmux, &testTxPool{added: newtx}, pow, blockchain, ca)
 	if err != nil {
 		return nil, err
 	}

eth/peer.go

@@ -196,7 +196,7 @@ func (p *peer) SendBlockHeaders(headers []*types.Header) error {
 }
 
 // SendBlockBodies sends a batch of block contents to the remote peer.
-func (p *peer) SendBlockBodies(bodies []*blockBody) error {
+func (p *peer) SendBlockBodies(bodies []*types.Body) error {
 	return p2p.Send(p.rw, BlockBodiesMsg, blockBodiesData(bodies))
 }
 

eth/protocol.go

@@ -201,14 +201,8 @@ type newBlockData struct {
 	TD    *big.Int
 }
 
-// blockBody represents the data content of a single block.
-type blockBody struct {
-	Transactions []*types.Transaction // Transactions contained within a block
-	Uncles       []*types.Header      // Uncles contained within a block
-}
-
 // blockBodiesData is the network packet for block content distribution.
-type blockBodiesData []*blockBody
+type blockBodiesData []*types.Body
 
 // nodeDataData is the network response packet for a node data retrieval.
 type nodeDataData []struct {

miner/worker.go

@@ -359,7 +359,7 @@ func (self *worker) push(work *Work) {
 
 // makeCurrent creates a new environment for the current cycle.
 func (self *worker) makeCurrent(parent *types.Block, header *types.Header) error {
-	state, err := state.New(parent.Root(), self.eth.ChainDb())
+	state, err := state.New(parent.Root(), self.eth.ChainAccess())
 	if err != nil {
 		return err
 	}

rpc/api/debug.go

@@ -119,7 +119,7 @@ func (self *debugApi) DumpBlock(req *shared.Request) (interface{}, error) {
 		return nil, fmt.Errorf("block #%d not found", args.BlockNumber)
 	}
 
-	stateDb, err := state.New(block.Root(), self.ethereum.ChainDb())
+	stateDb, err := state.New(block.Root(), self.ethereum.ChainAccess())
 	if err != nil {
 		return nil, err
 	}

rpc/api/eth.go

@@ -19,9 +19,8 @@ package api
 import (
 	"bytes"
 	"encoding/json"
-	"math/big"
-
 	"fmt"
+	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/natspec"
@@ -29,6 +28,7 @@ import (
 	"github.com/ethereum/go-ethereum/rpc/codec"
 	"github.com/ethereum/go-ethereum/rpc/shared"
 	"github.com/ethereum/go-ethereum/xeth"
+	"golang.org/x/net/context"
 	"gopkg.in/fatih/set.v0"
 )
 
@@ -153,8 +153,8 @@ func (self *ethApi) GetBalance(req *shared.Request) (interface{}, error) {
 	if err := self.codec.Decode(req.Params, &args); err != nil {
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
-
+	res := self.xeth.WithCtx(req.GetCtx()).AtStateNum(args.BlockNumber).BalanceAt(args.Address)
-	return self.xeth.AtStateNum(args.BlockNumber).BalanceAt(args.Address), nil
+	return res, nil
 }
 
 func (self *ethApi) ProtocolVersion(req *shared.Request) (interface{}, error) {
@@ -170,6 +170,9 @@ func (self *ethApi) IsMining(req *shared.Request) (interface{}, error) {
 }
 
 func (self *ethApi) IsSyncing(req *shared.Request) (interface{}, error) {
+	if self.ethereum.Downloader() == nil {
+		return false, nil
+	}
 	origin, current, height := self.ethereum.Downloader().Progress()
 	if current < height {
 		return map[string]interface{}{
@@ -191,7 +194,7 @@ func (self *ethApi) GetStorage(req *shared.Request) (interface{}, error) {
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	return self.xeth.AtStateNum(args.BlockNumber).State().SafeGet(args.Address).Storage(), nil
+	return self.xeth.WithCtx(req.GetCtx()).AtStateNum(args.BlockNumber).State().SafeGet(args.Address).Storage(), nil
 }
 
 func (self *ethApi) GetStorageAt(req *shared.Request) (interface{}, error) {
@@ -200,7 +203,7 @@ func (self *ethApi) GetStorageAt(req *shared.Request) (interface{}, error) {
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	return self.xeth.AtStateNum(args.BlockNumber).StorageAt(args.Address, args.Key), nil
+	return self.xeth.WithCtx(req.GetCtx()).AtStateNum(args.BlockNumber).StorageAt(args.Address, args.Key), nil
 }
 
 func (self *ethApi) GetTransactionCount(req *shared.Request) (interface{}, error) {
@@ -209,7 +212,7 @@ func (self *ethApi) GetTransactionCount(req *shared.Request) (interface{}, error
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	count := self.xeth.AtStateNum(args.BlockNumber).TxCountAt(args.Address)
+	count := self.xeth.WithCtx(req.GetCtx()).AtStateNum(args.BlockNumber).TxCountAt(args.Address)
 	return fmt.Sprintf("%#x", count), nil
 }
 
@@ -218,7 +221,7 @@ func (self *ethApi) GetBlockTransactionCountByHash(req *shared.Request) (interfa
 	if err := self.codec.Decode(req.Params, &args); err != nil {
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
-	block := self.xeth.EthBlockByHash(args.Hash)
+	block := self.xeth.WithCtx(req.GetCtx()).EthBlockByHash(args.Hash)
 	if block == nil {
 		return nil, nil
 	}
@@ -231,7 +234,7 @@ func (self *ethApi) GetBlockTransactionCountByNumber(req *shared.Request) (inter
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	block := self.xeth.EthBlockByNumber(args.BlockNumber)
+	block := self.xeth.WithCtx(req.GetCtx()).EthBlockByNumber(args.BlockNumber)
 	if block == nil {
 		return nil, nil
 	}
@@ -244,7 +247,7 @@ func (self *ethApi) GetUncleCountByBlockHash(req *shared.Request) (interface{},
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	block := self.xeth.EthBlockByHash(args.Hash)
+	block := self.xeth.WithCtx(req.GetCtx()).EthBlockByHash(args.Hash)
 	if block == nil {
 		return nil, nil
 	}
@@ -257,7 +260,7 @@ func (self *ethApi) GetUncleCountByBlockNumber(req *shared.Request) (interface{}
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	block := self.xeth.EthBlockByNumber(args.BlockNumber)
+	block := self.xeth.WithCtx(req.GetCtx()).EthBlockByNumber(args.BlockNumber)
 	if block == nil {
 		return nil, nil
 	}
@@ -269,7 +272,7 @@ func (self *ethApi) GetData(req *shared.Request) (interface{}, error) {
 	if err := self.codec.Decode(req.Params, &args); err != nil {
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
-	v := self.xeth.AtStateNum(args.BlockNumber).CodeAtBytes(args.Address)
+	v := self.xeth.WithCtx(req.GetCtx()).AtStateNum(args.BlockNumber).CodeAtBytes(args.Address)
 	return newHexData(v), nil
 }
 
@@ -337,7 +340,7 @@ func (self *ethApi) GetNatSpec(req *shared.Request) (interface{}, error) {
 }
 
 func (self *ethApi) EstimateGas(req *shared.Request) (interface{}, error) {
-	_, gas, err := self.doCall(req.Params)
+	_, gas, err := self.doCall(req.GetCtx(), req.Params)
 	if err != nil {
 		return nil, err
 	}
@@ -351,7 +354,7 @@ func (self *ethApi) EstimateGas(req *shared.Request) (interface{}, error) {
 }
 
 func (self *ethApi) Call(req *shared.Request) (interface{}, error) {
-	v, _, err := self.doCall(req.Params)
+	v, _, err := self.doCall(req.GetCtx(), req.Params)
 	if err != nil {
 		return nil, err
 	}
@@ -368,13 +371,13 @@ func (self *ethApi) Flush(req *shared.Request) (interface{}, error) {
 	return nil, shared.NewNotImplementedError(req.Method)
 }
 
-func (self *ethApi) doCall(params json.RawMessage) (string, string, error) {
+func (self *ethApi) doCall(ctx context.Context, params json.RawMessage) (string, string, error) {
 	args := new(CallArgs)
 	if err := self.codec.Decode(params, &args); err != nil {
 		return "", "", err
 	}
 
-	return self.xeth.AtStateNum(args.BlockNumber).Call(args.From, args.To, args.Value.String(), args.Gas.String(), args.GasPrice.String(), args.Data)
+	return self.xeth.WithCtx(ctx).AtStateNum(args.BlockNumber).Call(args.From, args.To, args.Value.String(), args.Gas.String(), args.GasPrice.String(), args.Data)
 }
 
 func (self *ethApi) GetBlockByHash(req *shared.Request) (interface{}, error) {
@@ -382,7 +385,7 @@ func (self *ethApi) GetBlockByHash(req *shared.Request) (interface{}, error) {
 	if err := self.codec.Decode(req.Params, &args); err != nil {
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
-	block := self.xeth.EthBlockByHash(args.BlockHash)
+	block := self.xeth.WithCtx(req.GetCtx()).EthBlockByHash(args.BlockHash)
 	if block == nil {
 		return nil, nil
 	}
@@ -395,7 +398,7 @@ func (self *ethApi) GetBlockByNumber(req *shared.Request) (interface{}, error) {
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	block := self.xeth.EthBlockByNumber(args.BlockNumber)
+	block := self.xeth.WithCtx(req.GetCtx()).EthBlockByNumber(args.BlockNumber)
 	if block == nil {
 		return nil, nil
 	}
@@ -408,7 +411,7 @@ func (self *ethApi) GetTransactionByHash(req *shared.Request) (interface{}, erro
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	tx, bhash, bnum, txi := self.xeth.EthTransactionByHash(args.Hash)
+	tx, bhash, bnum, txi := self.xeth.EthTransactionByHash(args.Hash) //ODR
 	if tx != nil {
 		v := NewTransactionRes(tx)
 		// if the blockhash is 0, assume this is a pending transaction
@@ -428,7 +431,7 @@ func (self *ethApi) GetTransactionByBlockHashAndIndex(req *shared.Request) (inte
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	raw := self.xeth.EthBlockByHash(args.Hash)
+	raw := self.xeth.WithCtx(req.GetCtx()).EthBlockByHash(args.Hash)
 	if raw == nil {
 		return nil, nil
 	}
@@ -446,7 +449,7 @@ func (self *ethApi) GetTransactionByBlockNumberAndIndex(req *shared.Request) (in
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	raw := self.xeth.EthBlockByNumber(args.BlockNumber)
+	raw := self.xeth.WithCtx(req.GetCtx()).EthBlockByNumber(args.BlockNumber)
 	if raw == nil {
 		return nil, nil
 	}
@@ -464,7 +467,7 @@ func (self *ethApi) GetUncleByBlockHashAndIndex(req *shared.Request) (interface{
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	raw := self.xeth.EthBlockByHash(args.Hash)
+	raw := self.xeth.WithCtx(req.GetCtx()).EthBlockByHash(args.Hash)
 	if raw == nil {
 		return nil, nil
 	}
@@ -482,7 +485,7 @@ func (self *ethApi) GetUncleByBlockNumberAndIndex(req *shared.Request) (interfac
 		return nil, shared.NewDecodeParamError(err.Error())
 	}
 
-	raw := self.xeth.EthBlockByNumber(args.BlockNumber)
+	raw := self.xeth.WithCtx(req.GetCtx()).EthBlockByNumber(args.BlockNumber)
 	if raw == nil {
 		return nil, nil
 	}
@@ -662,7 +665,7 @@ func (self *ethApi) GetTransactionReceipt(req *shared.Request) (interface{}, err
 
 	txhash := common.BytesToHash(common.FromHex(args.Hash))
 	tx, bhash, bnum, txi := self.xeth.EthTransactionByHash(args.Hash)
-	rec := self.xeth.GetTxReceipt(txhash)
+	rec := self.xeth.GetTxReceipt(txhash) //ODR
 	// We could have an error of "not found". Should disambiguate
 	// if err != nil {
 	// 	return err, nil

rpc/comms/comms.go

@@ -19,12 +19,12 @@ package comms
 import (
 	"io"
 	"net"
-
 	"fmt"
 	"strings"
-
 	"strconv"
+	"time"
 
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rpc/codec"
@@ -69,6 +69,8 @@ func handle(id int, conn net.Conn, api shared.EthereumApi, c codec.Codec) {
 		codec.Close()
 	}()
 
+	channelID := access.NewChannelID(time.Second)
+
 	for {
 		requests, isBatch, err := codec.ReadRequest()
 		if err == io.EOF {
@@ -78,11 +80,21 @@ func handle(id int, conn net.Conn, api shared.EthereumApi, c codec.Codec) {
 			return
 		}
 
+		ctx, _ := access.NewContext(channelID)
+
 		if isBatch {
 			responses := make([]*interface{}, len(requests))
 			responseCount := 0
+			var res interface{}
+			var err error
 			for _, req := range requests {
-				res, err := api.Execute(req)
+				if access.Terminated(ctx) {
+					res = nil
+					err = ctx.Err()
+				} else {
+					req.SetCtx(ctx)
+					res, err = api.Execute(req)
+				}
 				if req.Id != nil {
 					rpcResponse := shared.NewRpcResponse(req.Id, req.Jsonrpc, res, err)
 					responses[responseCount] = rpcResponse
@@ -97,7 +109,12 @@ func handle(id int, conn net.Conn, api shared.EthereumApi, c codec.Codec) {
 			}
 		} else {
 			var rpcResponse interface{}
+			requests[0].SetCtx(ctx)
 			res, err := api.Execute(requests[0])
+			if access.Terminated(ctx) {
+				res = nil
+				err = ctx.Err()
+			}
 
 			rpcResponse = shared.NewRpcResponse(requests[0].Id, requests[0].Jsonrpc, res, err)
 			err = codec.WriteResponse(rpcResponse)

rpc/comms/http.go

@@ -29,6 +29,7 @@ import (
 	"io"
 	"io/ioutil"
 
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rpc/codec"
@@ -67,6 +68,7 @@ type stopServer struct {
 type handler struct {
 	codec codec.Codec
 	api   shared.EthereumApi
+	channelID	*access.OdrChannelID
 }
 
 // StartHTTP starts listening for RPC requests sent via HTTP.
@@ -82,7 +84,8 @@ func StartHttp(cfg HttpConfig, codec codec.Codec, api shared.EthereumApi) error
 		return nil // RPC service already running on given host/port
 	}
 	// Set up the request handler, wrapping it with CORS headers if configured.
-	handler := http.Handler(&handler{codec, api})
+	channelID := access.NewChannelID(time.Second)
+	handler := http.Handler(&handler{codec, api, channelID})
 	if len(cfg.CorsDomain) > 0 {
 		opts := cors.Options{
 			AllowedMethods: []string{"POST"},
@@ -121,9 +124,15 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	}
 
 	c := h.codec.New(nil)
+	ctx, _ := access.NewContext(h.channelID)
 	var rpcReq shared.Request
 	if err = c.Decode(payload, &rpcReq); err == nil {
+		rpcReq.SetCtx(ctx)
 		reply, err := h.api.Execute(&rpcReq)
+		if access.Terminated(ctx) {
+			reply = nil
+			err = ctx.Err()
+		}
 		res := shared.NewRpcResponse(rpcReq.Id, rpcReq.Jsonrpc, reply, err)
 		sendJSON(w, &res)
 		return
@@ -133,8 +142,16 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	if err = c.Decode(payload, &reqBatch); err == nil {
 		resBatch := make([]*interface{}, len(reqBatch))
 		resCount := 0
+		var reply interface{}
+		var err error
 		for i, rpcReq := range reqBatch {
-			reply, err := h.api.Execute(&rpcReq)
+			if access.Terminated(ctx) {
+				reply = nil
+				err = ctx.Err()
+			} else {
+				rpcReq.SetCtx(ctx)
+				reply, err = h.api.Execute(&rpcReq)
+			}
 			if rpcReq.Id != nil { // this leaves nil entries in the response batch for later removal
 				resBatch[i] = shared.NewRpcResponse(rpcReq.Id, rpcReq.Jsonrpc, reply, err)
 				resCount += 1

rpc/comms/inproc.go

@@ -18,7 +18,9 @@ package comms
 
 import (
 	"fmt"
+	"time"
 
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/rpc/codec"
 	"github.com/ethereum/go-ethereum/rpc/shared"
 )
@@ -30,12 +32,14 @@ type InProcClient struct {
 	lastJsonrpc string
 	lastErr     error
 	lastRes     interface{}
+	channelID	*access.OdrChannelID
 }
 
 // Create a new in process client
 func NewInProcClient(codec codec.Codec) *InProcClient {
 	return &InProcClient{
 		codec: codec,
+		channelID: access.NewChannelID(time.Second),
 	}
 }
 
@@ -52,7 +56,13 @@ func (self *InProcClient) Send(req interface{}) error {
 	if r, ok := req.(*shared.Request); ok {
 		self.lastId = r.Id
 		self.lastJsonrpc = r.Jsonrpc
+		ctx, _ := access.NewContext(self.channelID)
+		r.SetCtx(ctx)
 		self.lastRes, self.lastErr = self.api.Execute(r)
+		if access.Terminated(ctx) {
+			self.lastRes = nil
+			self.lastErr = ctx.Err()
+		}
 		return self.lastErr
 	}
 

rpc/shared/types.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
+	"golang.org/x/net/context"
 )
 
 // Ethereum RPC API interface
@@ -39,11 +40,14 @@ type EthereumApi interface {
 }
 
 // RPC request
+// (ODR context is propagated inside the request struct because every
+//  request has its own context. It does not influence JSON encoding.)
 type Request struct {
 	Id      interface{}     `json:"id"`
 	Jsonrpc string          `json:"jsonrpc"`
 	Method  string          `json:"method"`
 	Params  json.RawMessage `json:"params"`
+	ctx 	context.Context
 }
 
 // RPC response
@@ -73,6 +77,16 @@ type ErrorObject struct {
 	// Data    interface{} `json:"data"`
 }
 
+// GetCtx returns the ODR context assigned to the request
+func (req *Request) GetCtx() context.Context {
+	return req.ctx
+}
+
+// SetCtx assigns an ODR context to the request
+func (req *Request) SetCtx(ctx context.Context) {
+	req.ctx = ctx
+}
+
 // Create RPC error response, this allows for custom error codes
 func NewRpcErrorResponse(id interface{}, jsonrpcver string, errCode int, err error) *ErrorResponse {
 	jsonerr := &ErrorObject{errCode, err.Error()}

tests/block_test_util.go

@@ -31,6 +31,7 @@ import (
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -217,7 +218,7 @@ func runBlockTest(test *BlockTest) error {
 // InsertPreState populates the given database with the genesis
 // accounts defined by the test.
 func (t *BlockTest) InsertPreState(db ethdb.Database, am *accounts.Manager) (*state.StateDB, error) {
-	statedb, err := state.New(common.Hash{}, db)
+	statedb, err := state.New(common.Hash{}, access.NewDbChainAccess(db))
 	if err != nil {
 		return nil, err
 	}

tests/state_test_util.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -103,7 +104,7 @@ func BenchStateTest(p string, conf bconf, b *testing.B) error {
 func benchStateTest(test VmTest, env map[string]string, b *testing.B) {
 	b.StopTimer()
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
+	statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 	for addr, account := range test.Pre {
 		obj := StateObjectFromAccount(db, addr, account)
 		statedb.SetStateObject(obj)
@@ -142,7 +143,7 @@ func runStateTests(tests map[string]VmTest, skipTests []string) error {
 
 func runStateTest(test VmTest) error {
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
+	statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 	for addr, account := range test.Pre {
 		obj := StateObjectFromAccount(db, addr, account)
 		statedb.SetStateObject(obj)

tests/util.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -89,7 +90,7 @@ func (self Log) Topics() [][]byte {
 }
 
 func StateObjectFromAccount(db ethdb.Database, addr string, account Account) *state.StateObject {
-	obj := state.NewStateObject(common.HexToAddress(addr), db)
+	obj := state.NewStateObject(access.NoOdr, common.HexToAddress(addr), access.NewDbChainAccess(db))
 	obj.SetBalance(common.Big(account.Balance))
 
 	if common.IsHex(account.Code) {

tests/vm_test_util.go

@@ -25,6 +25,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -108,7 +109,7 @@ func BenchVmTest(p string, conf bconf, b *testing.B) error {
 func benchVmTest(test VmTest, env map[string]string, b *testing.B) {
 	b.StopTimer()
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
+	statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 	for addr, account := range test.Pre {
 		obj := StateObjectFromAccount(db, addr, account)
 		statedb.SetStateObject(obj)
@@ -159,7 +160,7 @@ func runVmTests(tests map[string]VmTest, skipTests []string) error {
 
 func runVmTest(test VmTest) error {
 	db, _ := ethdb.NewMemDatabase()
-	statedb, _ := state.New(common.Hash{}, db)
+	statedb, _ := state.New(common.Hash{}, access.NewDbChainAccess(db))
 	for addr, account := range test.Pre {
 		obj := StateObjectFromAccount(db, addr, account)
 		statedb.SetStateObject(obj)

trie/encoding.go

@@ -58,6 +58,7 @@ func compactDecode(str []byte) []byte {
 	return base
 }
 
+// compactHexDecode decodes a series of nibbles from a byte array
 func compactHexDecode(str []byte) []byte {
 	l := len(str)*2 + 1
 	var nibbles = make([]byte, l)
@@ -69,6 +70,24 @@ func compactHexDecode(str []byte) []byte {
 	return nibbles
 }
 
+// compactHexEncode encodes a series of nibbles into a byte array
+func compactHexEncode(nibbles []byte) []byte {
+	nl := len(nibbles)
+	if nibbles[nl-1] == 16 {
+		nl--
+	}
+	l := (nl + 1) / 2
+	var str = make([]byte, l)
+	for i, _ := range str {
+		b := nibbles[i*2] * 16
+		if nl > i*2 {
+			b += nibbles[i*2+1]
+		}
+		str[i] = b
+	}
+	return str
+}
+
 func decodeCompact(key []byte) []byte {
 	l := len(key) / 2
 	var res = make([]byte, l)

trie/iterator.go

@@ -100,7 +100,7 @@ func (self *Iterator) next(node interface{}, key []byte, isIterStart bool) []byt
 		}
 
 	case hashNode:
-		return self.next(self.trie.resolveHash(node), key, isIterStart)
+		return self.next(self.trie.resolveHash(node, nil, nil), key, isIterStart)
 	}
 	return nil
 }
@@ -127,7 +127,7 @@ func (self *Iterator) key(node interface{}) []byte {
 			}
 		}
 	case hashNode:
-		return self.key(self.trie.resolveHash(node))
+		return self.key(self.trie.resolveHash(node, nil, nil))
 	}
 
 	return nil

trie/proof.go

@@ -10,6 +10,8 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
+type MerkleProof []rlp.RawValue
+
 // Prove constructs a merkle proof for key. The result contains all
 // encoded nodes on the path to the value at key. The value itself is
 // also included in the last node and can be retrieved by verifying
@@ -17,29 +19,28 @@ import (
 //
 // The returned proof is nil if the trie does not contain a value for key.
 // For existing keys, the proof will have at least one element.
-func (t *Trie) Prove(key []byte) []rlp.RawValue {
+func (t *Trie) Prove(key []byte) MerkleProof {
 	// Collect all nodes on the path to key.
 	key = compactHexDecode(key)
 	nodes := []node{}
 	tn := t.root
-	for len(key) > 0 {
+	for len(key) > 0 && tn != nil {
 		switch n := tn.(type) {
 		case shortNode:
 			if len(key) < len(n.Key) || !bytes.Equal(n.Key, key[:len(n.Key)]) {
 				// The trie doesn't contain the key.
-				return nil
+				tn = nil
-			}
+			} else {
 				tn = n.Val
+			}
 			key = key[len(n.Key):]
 			nodes = append(nodes, n)
 		case fullNode:
 			tn = n[key[0]]
 			key = key[1:]
 			nodes = append(nodes, n)
-		case nil:
-			return nil
 		case hashNode:
-			tn = t.resolveHash(n)
+			tn = t.resolveHash(n, nil, nil)
 		default:
 			panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
 		}
@@ -67,7 +68,7 @@ func (t *Trie) Prove(key []byte) []rlp.RawValue {
 // value for key in a trie with the given root hash. VerifyProof
 // returns an error if the proof contains invalid trie nodes or the
 // wrong value.
-func VerifyProof(rootHash common.Hash, key []byte, proof []rlp.RawValue) (value []byte, err error) {
+func VerifyProof(rootHash common.Hash, key []byte, proof MerkleProof) (value []byte, err error) {
 	key = compactHexDecode(key)
 	sha := sha3.NewKeccak256()
 	wantHash := rootHash.Bytes()
@@ -84,7 +85,12 @@ func VerifyProof(rootHash common.Hash, key []byte, proof []rlp.RawValue) (value
 		keyrest, cld := get(n, key)
 		switch cld := cld.(type) {
 		case nil:
+			if i != len(proof)-1 {
 				return nil, fmt.Errorf("key mismatch at proof node %d", i)
+			} else {
+				// The trie doesn't contain the key.
+				return nil, nil
+			}
 		case hashNode:
 			key = keyrest
 			wantHash = cld
@@ -98,6 +104,20 @@ func VerifyProof(rootHash common.Hash, key []byte, proof []rlp.RawValue) (value
 	return nil, errors.New("unexpected end of proof")
 }
 
+// StoreProof stores the new trie nodes obtained from a merkle proof in the database
+func StoreProof(db Database, proof MerkleProof) {
+	sha := sha3.NewKeccak256()
+	for _, buf := range proof {
+		sha.Reset()
+		sha.Write(buf)
+		hash := sha.Sum(nil)
+		val, _ := db.Get(hash)
+		if val == nil {
+			db.Put(hash, buf)
+		}
+	}
+}
+
 func get(tn node, key []byte) ([]byte, node) {
 	for len(key) > 0 {
 		switch n := tn.(type) {

trie/secure_trie.go

@@ -20,7 +20,9 @@ import (
 	"hash"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"golang.org/x/net/context"
 )
 
 var secureKeyPrefix = []byte("secure-key-")
@@ -50,16 +52,32 @@ type SecureTrie struct {
 // and returns ErrMissingRoot if the root node cannpt be found.
 // Accessing the trie loads nodes from db on demand.
 func NewSecure(root common.Hash, db Database) (*SecureTrie, error) {
+	return NewSecureOdr(access.NoOdr, root, db, nil)
+}
+
+// NewSecureOdr creates a trie with optional ODR. If ODR is enabled, an existing
+// root node in db is not required.
+func NewSecureOdr(ctx context.Context, root common.Hash, db Database, access OdrAccess) (*SecureTrie, error) {
 	if db == nil {
 		panic("NewSecure called with nil database")
 	}
-	trie, err := New(root, db)
+	trie, err := NewOdr(ctx, root, db, access)
 	if err != nil {
 		return nil, err
 	}
 	return &SecureTrie{Trie: trie}, nil
 }
 
+// CopySecureWithOdr creates a copy of a trie with additional ODR capability
+func (t *SecureTrie) CopySecureWithOdr(ctx context.Context, access OdrAccess) *SecureTrie {
+	return &SecureTrie{
+		Trie: t.Trie.CopyWithOdr(ctx, access),
+		hash: t.hash,
+		secKeyBuf: t.secKeyBuf,
+		hashKeyBuf: t.hashKeyBuf,
+	}
+}
+
 // Get returns the value for key stored in the trie.
 // The value bytes must not be modified by the caller.
 func (t *SecureTrie) Get(key []byte) []byte {

trie/trie.go

@@ -24,11 +24,13 @@ import (
 	"hash"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/access"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rlp"
+	"golang.org/x/net/context"
 )
 
 const defaultCacheCapacity = 800
@@ -46,6 +48,12 @@ var (
 
 var ErrMissingRoot = errors.New("missing root node")
 
+// OdrAccess is an interface to on-demand network access layer
+type OdrAccess interface {
+	OdrEnabled() bool		// is network access actually enabled
+	RetrieveKey(ctx context.Context, key []byte) bool // retrieve key from network and store it in local db
+}
+
 // Database must be implemented by backing stores for the trie.
 type Database interface {
 	DatabaseWriter
@@ -69,6 +77,8 @@ type DatabaseWriter interface {
 type Trie struct {
 	root   node
 	db     Database
+	access OdrAccess
+	ctx context.Context
 	*hasher
 }
 
@@ -79,19 +89,32 @@ type Trie struct {
 // New will panics if db is nil or root does not exist in the
 // database. Accessing the trie loads nodes from db on demand.
 func New(root common.Hash, db Database) (*Trie, error) {
-	trie := &Trie{db: db}
+	return NewOdr(access.NoOdr, root, db, nil)
+}
+
+// NewOdr creates a trie with optional ODR. If ODR is enabled, an existing
+// root node in db is not required.
+func NewOdr(ctx context.Context, root common.Hash, db Database, access OdrAccess) (*Trie, error) {
+	trie := &Trie{db: db, access: access, ctx: ctx}
 	if (root != common.Hash{}) && root != emptyRoot {
 		if db == nil {
 			panic("trie.New: cannot use existing root without a database")
 		}
+		if access == nil || !access.OdrEnabled() {
 			if v, _ := trie.db.Get(root[:]); len(v) == 0 {
 				return nil, ErrMissingRoot
 			}
+		}
 		trie.root = hashNode(root.Bytes())
 	}
 	return trie, nil
 }
 
+// CopyWithOdr creates a copy of a trie with additional ODR capability
+func (t *Trie) CopyWithOdr(ctx context.Context, access OdrAccess) *Trie {
+	return &Trie{db: t.db, root: t.root, access: access, ctx: ctx}
+}
+
 // Iterator returns an iterator over all mappings in the trie.
 func (t *Trie) Iterator() *Iterator {
 	return NewIterator(t)
@@ -101,22 +124,23 @@ func (t *Trie) Iterator() *Iterator {
 // The value bytes must not be modified by the caller.
 func (t *Trie) Get(key []byte) []byte {
 	key = compactHexDecode(key)
+	pos := 0
 	tn := t.root
-	for len(key) > 0 {
+	for pos < len(key) {
 		switch n := tn.(type) {
 		case shortNode:
-			if len(key) < len(n.Key) || !bytes.Equal(n.Key, key[:len(n.Key)]) {
+			if len(key)-pos < len(n.Key) || !bytes.Equal(n.Key, key[pos:pos+len(n.Key)]) {
 				return nil
 			}
 			tn = n.Val
-			key = key[len(n.Key):]
+			pos += len(n.Key)
 		case fullNode:
-			tn = n[key[0]]
+			tn = n[key[pos]]
-			key = key[1:]
+			pos++
 		case nil:
 			return nil
 		case hashNode:
-			tn = t.resolveHash(n)
+			tn = t.resolveHash(n, key[:pos], key[pos:])
 		default:
 			panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
 		}
@@ -133,13 +157,13 @@ func (t *Trie) Get(key []byte) []byte {
 func (t *Trie) Update(key, value []byte) {
 	k := compactHexDecode(key)
 	if len(value) != 0 {
-		t.root = t.insert(t.root, k, valueNode(value))
+		t.root = t.insert(t.root, nil, k, valueNode(value))
 	} else {
-		t.root = t.delete(t.root, k)
+		t.root = t.delete(t.root, nil, k)
 	}
 }
 
-func (t *Trie) insert(n node, key []byte, value node) node {
+func (t *Trie) insert(n node, prefix, key []byte, value node) node {
 	if len(key) == 0 {
 		return value
 	}
@@ -149,12 +173,12 @@ func (t *Trie) insert(n node, key []byte, value node) node {
 		// If the whole key matches, keep this short node as is
 		// and only update the value.
 		if matchlen == len(n.Key) {
-			return shortNode{n.Key, t.insert(n.Val, key[matchlen:], value)}
+			return shortNode{n.Key, t.insert(n.Val, append(prefix, key[:matchlen]...), key[matchlen:], value)}
 		}
 		// Otherwise branch out at the index where they differ.
 		var branch fullNode
-		branch[n.Key[matchlen]] = t.insert(nil, n.Key[matchlen+1:], n.Val)
+		branch[n.Key[matchlen]] = t.insert(nil, append(prefix, n.Key[:matchlen+1]...), n.Key[matchlen+1:], n.Val)
-		branch[key[matchlen]] = t.insert(nil, key[matchlen+1:], value)
+		branch[key[matchlen]] = t.insert(nil, append(prefix, key[:matchlen+1]...), key[matchlen+1:], value)
 		// Replace this shortNode with the branch if it occurs at index 0.
 		if matchlen == 0 {
 			return branch
@@ -163,7 +187,7 @@ func (t *Trie) insert(n node, key []byte, value node) node {
 		return shortNode{key[:matchlen], branch}
 
 	case fullNode:
-		n[key[0]] = t.insert(n[key[0]], key[1:], value)
+		n[key[0]] = t.insert(n[key[0]], append(prefix, key[0]), key[1:], value)
 		return n
 
 	case nil:
@@ -176,7 +200,7 @@ func (t *Trie) insert(n node, key []byte, value node) node {
 		//
 		// TODO: track whether insertion changed the value and keep
 		// n as a hash node if it didn't.
-		return t.insert(t.resolveHash(n), key, value)
+		return t.insert(t.resolveHash(n, prefix, key), prefix, key, value)
 
 	default:
 		panic(fmt.Sprintf("%T: invalid node: %v", n, n))
@@ -186,13 +210,13 @@ func (t *Trie) insert(n node, key []byte, value node) node {
 // Delete removes any existing value for key from the trie.
 func (t *Trie) Delete(key []byte) {
 	k := compactHexDecode(key)
-	t.root = t.delete(t.root, k)
+	t.root = t.delete(t.root, nil, k)
 }
 
 // delete returns the new root of the trie with key deleted.
 // It reduces the trie to minimal form by simplifying
 // nodes on the way up after deleting recursively.
-func (t *Trie) delete(n node, key []byte) node {
+func (t *Trie) delete(n node, prefix, key []byte) node {
 	switch n := n.(type) {
 	case shortNode:
 		matchlen := prefixLen(key, n.Key)
@@ -206,7 +230,7 @@ func (t *Trie) delete(n node, key []byte) node {
 		// from the subtrie. Child can never be nil here since the
 		// subtrie must contain at least two other values with keys
 		// longer than n.Key.
-		child := t.delete(n.Val, key[len(n.Key):])
+		child := t.delete(n.Val, append(prefix, key[:len(n.Key)]...), key[len(n.Key):])
 		switch child := child.(type) {
 		case shortNode:
 			// Deleting from the subtrie reduced it to another
@@ -221,7 +245,7 @@ func (t *Trie) delete(n node, key []byte) node {
 		}
 
 	case fullNode:
-		n[key[0]] = t.delete(n[key[0]], key[1:])
+		n[key[0]] = t.delete(n[key[0]], append(prefix, key[0]), key[1:])
 		// Check how many non-nil entries are left after deleting and
 		// reduce the full node to a short node if only one entry is
 		// left. Since n must've contained at least two children
@@ -250,7 +274,7 @@ func (t *Trie) delete(n node, key []byte) node {
 				// shortNode{..., shortNode{...}}.  Since the entry
 				// might not be loaded yet, resolve it just for this
 				// check.
-				cnode := t.resolve(n[pos])
+				cnode := t.resolve(n[pos], prefix, []byte{byte(pos)})
 				if cnode, ok := cnode.(shortNode); ok {
 					k := append([]byte{byte(pos)}, cnode.Key...)
 					return shortNode{k, cnode.Val}
@@ -273,7 +297,7 @@ func (t *Trie) delete(n node, key []byte) node {
 		//
 		// TODO: track whether deletion actually hit a key and keep
 		// n as a hash node if it didn't.
-		return t.delete(t.resolveHash(n), key)
+		return t.delete(t.resolveHash(n, prefix, key), prefix, key)
 
 	default:
 		panic(fmt.Sprintf("%T: invalid node: %v (%v)", n, n, key))
@@ -287,19 +311,28 @@ func concat(s1 []byte, s2 ...byte) []byte {
 	return r
 }
 
-func (t *Trie) resolve(n node) node {
+func (t *Trie) resolve(n node, prefix, suffix []byte) node {
 	if n, ok := n.(hashNode); ok {
-		return t.resolveHash(n)
+		return t.resolveHash(n, prefix, suffix)
 	}
 	return n
 }
 
-func (t *Trie) resolveHash(n hashNode) node {
+func (t *Trie) resolveHash(n hashNode, prefix, suffix []byte) node {
 	if v, ok := globalCache.Get(n); ok {
 		return v
 	}
 	enc, err := t.db.Get(n)
 	if err != nil || enc == nil {
+		if prefix != nil || suffix != nil {
+			key := compactHexEncode(append(prefix, suffix...))
+			if t.access != nil && t.access.RetrieveKey(t.ctx, key) {
+				enc, err = t.db.Get(n)
+			}
+		}
+	}
+	if err != nil || enc == nil {
+
 		// TODO: This needs to be improved to properly distinguish errors.
 		// Disk I/O errors shouldn't produce nil (and cause a
 		// consensus failure or weird crash), but it is unclear how
@@ -348,6 +381,11 @@ func (t *Trie) Commit() (root common.Hash, err error) {
 // the changes made to db are written back to the trie's attached
 // database before using the trie.
 func (t *Trie) CommitTo(db DatabaseWriter) (root common.Hash, err error) {
+	if access.Terminated(t.ctx) {
+		// we should never commit potentially corrupt trie nodes to the db
+		return common.Hash{}, t.ctx.Err()
+	}	
+	
 	n, err := t.hashRoot(db)
 	if err != nil {
 		return (common.Hash{}), err

xeth/state.go

@@ -45,7 +45,7 @@ func (self *State) SafeGet(addr string) *Object {
 func (self *State) safeGet(addr string) *state.StateObject {
 	object := self.state.GetStateObject(common.HexToAddress(addr))
 	if object == nil {
-		object = state.NewStateObject(common.HexToAddress(addr), self.xeth.backend.ChainDb())
+		object = state.NewStateObject(self.state.Ctx(), common.HexToAddress(addr), self.xeth.backend.ChainAccess())
 	}
 
 	return object

xeth/xeth.go

@@ -41,6 +41,7 @@ import (
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/miner"
 	"github.com/ethereum/go-ethereum/rlp"
+	"golang.org/x/net/context"
 )
 
 var (
@@ -84,6 +85,7 @@ type XEth struct {
 	state         *State
 	whisper       *Whisper
 	filterManager *filters.FilterSystem
+	ctx context.Context
 }
 
 func NewTest(eth *eth.Ethereum, frontend Frontend) *XEth {
@@ -207,15 +209,15 @@ func (self *XEth) AtStateNum(num int64) *XEth {
 	var err error
 	switch num {
 	case -2:
-		st = self.backend.Miner().PendingState().Copy()
+		st = self.backend.Miner().PendingState().CopyOdr(self.ctx)
 	default:
 		if block := self.getBlockByHeight(num); block != nil {
-			st, err = state.New(block.Root(), self.backend.ChainDb())
+			st, err = state.NewOdr(self.ctx, block.Root(), self.backend.ChainAccess())
 			if err != nil {
 				return nil
 			}
 		} else {
-			st, err = state.New(self.backend.BlockChain().GetBlockByNumber(0).Root(), self.backend.ChainDb())
+			st, err = state.NewOdr(self.ctx, self.backend.BlockChain().GetBlockByNumberOdr(self.ctx, 0).Root(), self.backend.ChainAccess())
 			if err != nil {
 				return nil
 			}
@@ -238,6 +240,19 @@ func (self *XEth) WithState(statedb *state.StateDB) *XEth {
 
 func (self *XEth) State() *State { return self.state }
 
+// WithCtx creates a copy of the XEth object with a new ODR context
+func (self *XEth) WithCtx(ctx context.Context) *XEth {
+	xeth := &XEth{
+		backend:  self.backend,
+		frontend: self.frontend,
+		gpo:      self.gpo,
+		ctx:      ctx,
+	}
+
+	xeth.state = NewState(xeth, self.state.State().CopyOdr(ctx))
+	return xeth
+}
+
 // subscribes to new head block events and
 // waits until blockchain height is greater n at any time
 // given the current head, waits for the next chain event
@@ -270,7 +285,7 @@ func (self *XEth) UpdateState() (wait chan *big.Int) {
 						wait <- n
 						n = nil
 					}
-					statedb, err := state.New(event.Block.Root(), self.backend.ChainDb())
+					statedb, err := state.New(event.Block.Root(), self.backend.ChainAccess())
 					if err != nil {
 						glog.V(logger.Error).Infoln("Could not create new state: %v", err)
 						return
@@ -305,19 +320,19 @@ func (self *XEth) getBlockByHeight(height int64) *types.Block {
 		num = uint64(height)
 	}
 
-	return self.backend.BlockChain().GetBlockByNumber(num)
+	return self.backend.BlockChain().GetBlockByNumberOdr(self.ctx, num)
 }
 
 func (self *XEth) BlockByHash(strHash string) *Block {
 	hash := common.HexToHash(strHash)
-	block := self.backend.BlockChain().GetBlock(hash)
+	block := self.backend.BlockChain().GetBlockOdr(self.ctx, hash)
 
 	return NewBlock(block)
 }
 
 func (self *XEth) EthBlockByHash(strHash string) *types.Block {
 	hash := common.HexToHash(strHash)
-	block := self.backend.BlockChain().GetBlock(hash)
+	block := self.backend.BlockChain().GetBlockOdr(self.ctx, hash)
 
 	return block
 }
@@ -379,11 +394,11 @@ func (self *XEth) CurrentBlock() *types.Block {
 }
 
 func (self *XEth) GetBlockReceipts(bhash common.Hash) types.Receipts {
-	return self.backend.BlockProcessor().GetBlockReceipts(bhash)
+	return self.backend.BlockProcessor().GetBlockReceipts(bhash) //ODR
 }
 
-func (self *XEth) GetTxReceipt(txhash common.Hash) *types.Receipt {
+func (self *XEth) GetTxReceipt(txhash common.Hash) *types.Receipt { //ODR
-	return core.GetReceipt(self.backend.ChainDb(), txhash)
+	return core.GetReceipt(self.backend.ChainAccess(), txhash) //TODO
 }
 
 func (self *XEth) GasLimit() *big.Int {
@@ -547,7 +562,7 @@ func (self *XEth) NewLogFilter(earliest, latest int64, skip, max int, address []
 	self.logMu.Lock()
 	defer self.logMu.Unlock()
 
-	filter := filters.New(self.backend.ChainDb())
+	filter := filters.New(self.backend.ChainAccess())
 	id := self.filterManager.Add(filter)
 	self.logQueue[id] = &logQueue{timeout: time.Now()}
 
@@ -571,7 +586,7 @@ func (self *XEth) NewTransactionFilter() int {
 	self.transactionMu.Lock()
 	defer self.transactionMu.Unlock()
 
-	filter := filters.New(self.backend.ChainDb())
+	filter := filters.New(self.backend.ChainAccess())
 	id := self.filterManager.Add(filter)
 	self.transactionQueue[id] = &hashQueue{timeout: time.Now()}
 
@@ -590,7 +605,7 @@ func (self *XEth) NewBlockFilter() int {
 	self.blockMu.Lock()
 	defer self.blockMu.Unlock()
 
-	filter := filters.New(self.backend.ChainDb())
+	filter := filters.New(self.backend.ChainAccess())
 	id := self.filterManager.Add(filter)
 	self.blockQueue[id] = &hashQueue{timeout: time.Now()}
 
@@ -657,7 +672,7 @@ func (self *XEth) Logs(id int) vm.Logs {
 }
 
 func (self *XEth) AllLogs(earliest, latest int64, skip, max int, address []string, topics [][]string) vm.Logs {
-	filter := filters.New(self.backend.ChainDb())
+	filter := filters.New(self.backend.ChainAccess())
 	filter.SetBeginBlock(earliest)
 	filter.SetEndBlock(latest)
 	filter.SetAddresses(cAddress(address))
@@ -829,7 +844,7 @@ func (self *XEth) PushTx(encodedTx string) (string, error) {
 }
 
 func (self *XEth) Call(fromStr, toStr, valueStr, gasStr, gasPriceStr, dataStr string) (string, string, error) {
-	statedb := self.State().State().Copy()
+	statedb := self.State().State().CopyWithCtx()
 	var from *state.StateObject
 	if len(fromStr) == 0 {
 		accounts, err := self.backend.AccountManager().Accounts()