core/vm: removed context.Context from evm ENV (review change)

Removed the context.Context cancellation approach from vm.Environment
and added a Cancel method instead; this however makes the environment a
one shot object due to the `evm.abort` being set to 1, disallowing any
further operation to be done using that environment.

core/evm.go

@@ -17,7 +17,6 @@
 package core
 
 import (
-	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -34,8 +33,6 @@ type HeaderFetcher interface {
 // NewEVMContext creates a new context for use in the EVM.
 func NewEVMContext(msg Message, header *types.Header, chain HeaderFetcher) vm.Context {
 	return vm.Context{
-		Context: context.TODO(),
-
 		CanTransfer: CanTransfer,
 		Transfer:    Transfer,
 		GetHash:     GetHashFn(header, chain),

core/vm/environment.go

@@ -17,7 +17,6 @@
 package vm
 
 import (
-	"context"
 	"fmt"
 	"math/big"
 	"sync/atomic"
@@ -37,7 +36,6 @@ type (
 
 // Context provides the EVM with auxilary information. Once provided it shouldn't be modified.
 type Context struct {
-	context.Context
 	// CanTransfer returns whether the account contains
 	// sufficient ether to transfer the value
 	CanTransfer CanTransferFunc
@@ -80,8 +78,6 @@ type EVM struct {
 	// abort is used to abort the EVM calling operations
 	// NOTE: must be set atomically
 	abort int32
-
-	quit chan struct{}
 }
 
 // NewEVM retutrns a new EVM evmironment.
@@ -97,27 +93,16 @@ func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmCon
 	return evm
 }
 
-func (evm *EVM) init() {
+// Cancel cancels any running EVM operation. This may be called concurrently and it's safe to be
-	evm.quit = make(chan struct{})
+// called multiple times.
-	go func() {
+func (evm *EVM) Cancel() {
-		select {
+	atomic.StoreInt32(&evm.abort, 1)
-		case <-evm.quit:
-			return
-		case <-evm.Context.Done():
-			atomic.StoreInt32(&evm.abort, 1)
-		}
-	}()
 }
 
 // Call executes the contract associated with the addr with the given input as paramaters. It also handles any
 // necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
 // case of an execution error or failed value transfer.
 func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) (ret []byte, err error) {
-	if evm.depth == 0 {
-		evm.init()
-		defer close(evm.quit)
-	}
-
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 
@@ -178,11 +163,6 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas,
 //
 // CallCode differs from Call in the sense that it executes the given address' code with the caller as context.
 func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) (ret []byte, err error) {
-	if evm.depth == 0 {
-		evm.init()
-		defer close(evm.quit)
-	}
-
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 
@@ -229,11 +209,6 @@ func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte,
 // DelegateCall differs from CallCode in the sense that it executes the given address' code with the caller as context
 // and the caller is set to the caller of the caller.
 func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas *big.Int) (ret []byte, err error) {
-	if evm.depth == 0 {
-		evm.init()
-		defer close(evm.quit)
-	}
-
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 
@@ -269,11 +244,6 @@ func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []by
 
 // Create creates a new contract using code as deployment code.
 func (evm *EVM) Create(caller ContractRef, code []byte, gas, value *big.Int) (ret []byte, contractAddr common.Address, err error) {
-	if evm.depth == 0 {
-		evm.init()
-		defer close(evm.quit)
-	}
-
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 

core/vm/logger_test.go

@@ -17,7 +17,6 @@
 package vm
 
 import (
-	"context"
 	"math/big"
 	"testing"
 
@@ -53,7 +52,7 @@ func (d dummyStateDB) GetAccount(common.Address) Account {
 
 func TestStoreCapture(t *testing.T) {
 	var (
-		env      = NewEVM(Context{Context: context.TODO()}, nil, params.TestChainConfig, Config{EnableJit: false, ForceJit: false})
+		env      = NewEVM(Context{}, nil, params.TestChainConfig, Config{EnableJit: false, ForceJit: false})
 		logger   = NewStructLogger(nil)
 		mem      = NewMemory()
 		stack    = newstack()
@@ -80,7 +79,7 @@ func TestStorageCapture(t *testing.T) {
 	var (
 		ref      = &dummyContractRef{}
 		contract = NewContract(ref, ref, new(big.Int), new(big.Int))
-		env      = NewEVM(Context{Context: context.TODO()}, dummyStateDB{ref: ref}, params.TestChainConfig, Config{EnableJit: false, ForceJit: false})
+		env      = NewEVM(Context{}, dummyStateDB{ref: ref}, params.TestChainConfig, Config{EnableJit: false, ForceJit: false})
 		logger   = NewStructLogger(nil)
 		mem      = NewMemory()
 		stack    = newstack()

core/vm/runtime/env.go

@@ -17,7 +17,6 @@
 package runtime
 
 import (
-	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -28,7 +27,6 @@ import (
 
 func NewEnv(cfg *Config, state *state.StateDB) *vm.EVM {
 	context := vm.Context{
-		Context:     context.TODO(),
 		CanTransfer: core.CanTransfer,
 		Transfer:    core.Transfer,
 		GetHash:     func(uint64) common.Hash { return common.Hash{} },

tests/util.go

@@ -18,7 +18,6 @@ package tests
 
 import (
 	"bytes"
-	"context"
 	"encoding/hex"
 	"fmt"
 	"math/big"
@@ -191,8 +190,6 @@ func NewEVMEnvironment(vmTest bool, chainConfig *params.ChainConfig, statedb *st
 	}
 
 	context := vm.Context{
-		Context: context.TODO(),
-
 		CanTransfer: canTransfer,
 		Transfer:    transfer,
 		GetHash: func(n uint64) common.Hash {