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swarm/storage/feed/lookup: First LE that works

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This commit is contained in:
Javier Peletier 2019-03-28 16:14:33 +01:00
parent db83ba4067
commit 9f31234beb
2 changed files with 166 additions and 11 deletions
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136
swarm/storage/feed/lookup/lookup.go
View file

@ -20,7 +20,10 @@ so they can be found
*/
package lookup
import "context"
import (
"context"
"time"
)
const maxuint64 = ^uint64(0)
@ -43,7 +46,7 @@ type Algorithm func(ctx context.Context, now uint64, hint Epoch, read ReadFunc)
// read() will be called on each lookup attempt
// Returns an error only if read() returns an error
// Returns nil if an update was not found
var Lookup Algorithm = FluzCapacitorAlgorithm
var Lookup Algorithm = LongEarthAlgorithm
// ReadFunc is a handler called by Lookup each time it attempts to find a value
// It should return <nil> if a value is not found
@ -180,4 +183,133 @@ func FluzCapacitorAlgorithm(ctx context.Context, now uint64, hint Epoch, read Re
}
t = base - 1
}
}
type StepFunc func(ctx context.Context, t uint64, hint Epoch) interface{}
func LongEarthAlgorithm(ctx context.Context, now uint64, hint Epoch, read ReadFunc) (interface{}, error) {
errc := make(chan error)
var step StepFunc
step = func(ctxS context.Context, t uint64, hint Epoch) interface{} {
var valueA, valueB, valueR interface{}
ctxR, cancelR := context.WithCancel(ctxS)
ctxA, cancelA := context.WithCancel(ctxS)
ctxB, cancelB := context.WithCancel(ctxS)
epoch := GetNextEpoch(hint, t)
lookAhead := func() {
valueA = step(ctxA, t, epoch)
if valueA != nil {
cancelB()
cancelR()
}
}
lookBack := func() {
var err error
if epoch.Base() == hint.Base() {
// we have reached the hint itself
if hint == worstHint {
valueB = nil
return
}
// check it out
valueB, err = read(ctxB, hint, now)
if valueB != nil || err == context.Canceled {
return
}
if err != nil {
errc <- err
return
}
// bad hint.
valueB = step(ctxB, hint.Base(), worstHint)
return
}
base := epoch.Base()
if base == 0 {
return
}
valueB = step(ctxB, base-1, hint)
}
go func() {
defer cancelR()
var err error
valueR, err = read(ctxR, epoch, now)
if valueR == nil {
cancelA()
} else {
cancelB()
}
if err != nil && err != context.Canceled {
errc <- err
}
}()
go func() {
defer cancelA()
if epoch.Level == LowestLevel || epoch.Equals(hint) {
return
}
select {
case <-time.After(250 * time.Millisecond):
lookAhead()
case <-ctxR.Done():
if valueR != nil {
lookAhead()
}
case <-ctxA.Done():
}
}()
go func() {
defer cancelB()
select {
case <-time.After(250 * time.Millisecond):
lookBack()
case <-ctxR.Done():
if valueR == nil {
lookBack()
}
case <-ctxB.Done():
}
}()
<-ctxA.Done()
if valueA != nil {
return valueA
}
<-ctxR.Done()
if valueR != nil {
return valueR
}
<-ctxB.Done()
return valueB
}
var value interface{}
ctx, cancel := context.WithCancel(ctx)
defer cancel()
go func() {
value = step(ctx, now, hint)
cancel()
}()
select {
case <-ctx.Done():
return value, nil
case err := <-errc:
return nil, err
}
}

41
swarm/storage/feed/lookup/lookup_test.go
View file

@ -20,7 +20,9 @@ import (
"context"
"fmt"
"math/rand"
"sync/atomic"
"testing"
"time"
"github.com/ethereum/go-ethereum/swarm/log"
"github.com/ethereum/go-ethereum/swarm/storage/feed/lookup"
@ -31,6 +33,10 @@ type Data struct {
Time uint64
}
func (d *Data) String() string {
return fmt.Sprintf("%d-%d", d.Payload, d.Time)
}
type Store map[lookup.EpochID]*Data
func write(store Store, epoch lookup.Epoch, value *Data) {
@ -50,15 +56,21 @@ const Day = 60 * 60 * 24
const Year = Day * 365
const Month = Day * 30
func makeReadFunc(store Store, counter *int) lookup.ReadFunc {
func makeReadFunc(store Store, counter *int32) lookup.ReadFunc {
return func(ctx context.Context, epoch lookup.Epoch, now uint64) (interface{}, error) {
*counter++
atomic.AddInt32(counter, 1)
select {
case <-time.After(1000 * time.Millisecond):
case <-ctx.Done():
return nil, ctx.Err()
}
data := store[epoch.ID()]
var valueStr string
if data != nil {
valueStr = fmt.Sprintf("%d", data.Payload)
}
log.Debug("Read: %d-%d, value='%s'\n", epoch.Base(), epoch.Level, valueStr)
//fmt.Printf("Read: %d-%d, value='%s'\n", epoch.Base(), epoch.Level, valueStr)
if data != nil && data.Time <= now {
return data, nil
}
@ -67,9 +79,8 @@ func makeReadFunc(store Store, counter *int) lookup.ReadFunc {
}
func TestLookup(t *testing.T) {
store := make(Store)
readCount := 0
var readCount int32 = 0
readFunc := makeReadFunc(store, &readCount)
// write an update every month for 12 months 3 years ago and then silence for two years
@ -93,6 +104,7 @@ func TestLookup(t *testing.T) {
if err != nil {
t.Fatal(err)
}
fmt.Printf("readcount=%d\n", readCount)
readCountWithoutHint := readCount
@ -142,7 +154,7 @@ func TestLookup(t *testing.T) {
func TestOneUpdateAt0(t *testing.T) {
store := make(Store)
readCount := 0
var readCount int32 = 0
readFunc := makeReadFunc(store, &readCount)
now := uint64(1533903729)
@ -167,7 +179,7 @@ func TestOneUpdateAt0(t *testing.T) {
func TestBadHint(t *testing.T) {
store := make(Store)
readCount := 0
var readCount int32 = 0
readFunc := makeReadFunc(store, &readCount)
now := uint64(1533903729)
@ -299,7 +311,7 @@ func TestContextCancellation(t *testing.T) {
func TestLookupFail(t *testing.T) {
store := make(Store)
readCount := 0
var readCount int32 = 0
readFunc := makeReadFunc(store, &readCount)
now := uint64(1533903729)
@ -324,7 +336,7 @@ func TestLookupFail(t *testing.T) {
func TestHighFreqUpdates(t *testing.T) {
store := make(Store)
readCount := 0
var readCount int32 = 0
readFunc := makeReadFunc(store, &readCount)
now := uint64(1533903729)
@ -388,7 +400,7 @@ func TestHighFreqUpdates(t *testing.T) {
func TestSparseUpdates(t *testing.T) {
store := make(Store)
readCount := 0
var readCount int32 = 0
readFunc := makeReadFunc(store, &readCount)
// write an update every 5 years 3 times starting in Jan 1st 1970 and then silence
@ -513,3 +525,14 @@ func CookGetNextLevelTests(t *testing.T) {
}
fmt.Println(st)
}
func TestTest(t *testing.T) {
hint := lookup.Epoch{
Time: 20,
Level: 2,
}
e := lookup.GetNextEpoch(hint, 21)
fmt.Println(e)
}