all: import "context" instead of "golang.org/x/net/context"

There is no need to depend on the old context package now that the
minimum Go version is 1.7. The move to "context" eliminates our weird
vendoring setup. Some vendored code still uses golang.org/x/net/context
and it is now vendored in the normal way.

This change triggered new vet checks around context.WithTimeout which
didn't fire with golang.org/x/net/context.

12 files changed, 39 insertions, 26 deletions

diff --git a/light/lightchain.go b/light/lightchain.go
index 4715d47ab..82b7a5866 100644
--- a/light/lightchain.go
+++ b/light/lightchain.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"math/big"
 	"sync"
 	"sync/atomic"
@@ -32,7 +33,6 @@ import (
 	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/hashicorp/golang-lru"
-	"golang.org/x/net/context"
 )
 
 var (
diff --git a/light/lightchain_test.go b/light/lightchain_test.go
index 8a99c69f1..7460fd1a3 100644
--- a/light/lightchain_test.go
+++ b/light/lightchain_test.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"fmt"
 	"math/big"
 	"runtime"
@@ -30,7 +31,6 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/pow"
 	"github.com/hashicorp/golang-lru"
-	"golang.org/x/net/context"
 )
 
 // So we can deterministically seed different blockchains
diff --git a/light/odr.go b/light/odr.go
index 4f6ef6b9e..ca6364f28 100644
--- a/light/odr.go
+++ b/light/odr.go
@@ -19,6 +19,7 @@
 package light
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -27,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 // NoOdr is the default context passed to an ODR capable function when the ODR
diff --git a/light/odr_test.go b/light/odr_test.go
index e2eced346..ba82ec04f 100644
--- a/light/odr_test.go
+++ b/light/odr_test.go
@@ -18,6 +18,7 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"math/big"
 	"testing"
@@ -36,7 +37,6 @@ import (
 	"github.com/ethereum/go-ethereum/pow"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
-	"golang.org/x/net/context"
 )
 
 var (
@@ -277,8 +277,11 @@ func testChainOdr(t *testing.T, protocol int, expFail uint64, fn odrTestFn) {
 		for i := uint64(0); i <= blockchain.CurrentHeader().Number.Uint64(); i++ {
 			bhash := core.GetCanonicalHash(sdb, i)
 			b1 := fn(NoOdr, sdb, blockchain, nil, bhash)
-			ctx, _ := context.WithTimeout(context.Background(), 200*time.Millisecond)
+
+			ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
+			defer cancel()
 			b2 := fn(ctx, ldb, nil, lightchain, bhash)
+
 			eq := bytes.Equal(b1, b2)
 			exp := i < expFail
 			if exp && !eq {
diff --git a/light/odr_util.go b/light/odr_util.go
index 17e9aadcb..d7f8458f1 100644
--- a/light/odr_util.go
+++ b/light/odr_util.go
@@ -18,6 +18,7 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"math/big"
 
@@ -27,7 +28,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 var sha3_nil = crypto.Keccak256Hash(nil)
diff --git a/light/state.go b/light/state.go
index d3e047ef4..b184dc3a5 100644
--- a/light/state.go
+++ b/light/state.go
@@ -17,11 +17,11 @@
 package light
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
-	"golang.org/x/net/context"
 )
 
 // LightState is a memory representation of a state.
diff --git a/light/state_object.go b/light/state_object.go
index f33ba217e..a54ea1d9f 100644
--- a/light/state_object.go
+++ b/light/state_object.go
@@ -18,13 +18,13 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 var emptyCodeHash = crypto.Keccak256(nil)
diff --git a/light/state_test.go b/light/state_test.go
index d594ab9ff..e776efec8 100644
--- a/light/state_test.go
+++ b/light/state_test.go
@@ -18,6 +18,7 @@ package light
 
 import (
 	"bytes"
+	"context"
 	"math/big"
 	"testing"
 
@@ -26,7 +27,6 @@ import (
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
-	"golang.org/x/net/context"
 )
 
 func makeTestState() (common.Hash, ethdb.Database) {
diff --git a/light/trie.go b/light/trie.go
index c5525358a..1440f2fbf 100644
--- a/light/trie.go
+++ b/light/trie.go
@@ -17,9 +17,10 @@
 package light
 
 import (
+	"context"
+
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/trie"
-	"golang.org/x/net/context"
 )
 
 // LightTrie is an ODR-capable wrapper around trie.SecureTrie
diff --git a/light/txpool.go b/light/txpool.go
index 5eb1ba801..446195806 100644
--- a/light/txpool.go
+++ b/light/txpool.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"fmt"
 	"sync"
 	"time"
@@ -29,7 +30,6 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
-	"golang.org/x/net/context"
 )
 
 // txPermanent is the number of mined blocks after a mined transaction is
@@ -230,13 +230,13 @@ func (pool *TxPool) rollbackTxs(hash common.Hash, txc txStateChanges) {
 	}
 }
 
-// setNewHead sets a new head header, processing (and rolling back if necessary)
+// reorgOnNewHead sets a new head header, processing (and rolling back if necessary)
 // the blocks since the last known head and returns a txStateChanges map containing
 // the recently mined and rolled back transaction hashes. If an error (context
 // timeout) occurs during checking new blocks, it leaves the locally known head
 // at the latest checked block and still returns a valid txStateChanges, making it
 // possible to continue checking the missing blocks at the next chain head event
-func (pool *TxPool) setNewHead(ctx context.Context, newHeader *types.Header) (txStateChanges, error) {
+func (pool *TxPool) reorgOnNewHead(ctx context.Context, newHeader *types.Header) (txStateChanges, error) {
 	txc := make(txStateChanges)
 	oldh := pool.chain.GetHeaderByHash(pool.head)
 	newh := newHeader
@@ -305,20 +305,28 @@ func (pool *TxPool) eventLoop() {
 	for ev := range pool.events.Chan() {
 		switch ev.Data.(type) {
 		case core.ChainHeadEvent:
-			head := pool.chain.CurrentHeader()
-			pool.mu.Lock()
-			ctx, _ := context.WithTimeout(context.Background(), blockCheckTimeout)
-			txc, _ := pool.setNewHead(ctx, head)
-			m, r := txc.getLists()
-			pool.relay.NewHead(pool.head, m, r)
-			pool.homestead = pool.config.IsHomestead(head.Number)
-			pool.signer = types.MakeSigner(pool.config, head.Number)
-			pool.mu.Unlock()
-			time.Sleep(time.Millisecond) // hack in order to avoid hogging the lock; this part will be replaced by a subsequent PR
+			pool.setNewHead(ev.Data.(core.ChainHeadEvent).Block.Header())
+			// hack in order to avoid hogging the lock; this part will
+			// be replaced by a subsequent PR.
+			time.Sleep(time.Millisecond)
 		}
 	}
 }
 
+func (pool *TxPool) setNewHead(head *types.Header) {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
+
+	ctx, cancel := context.WithTimeout(context.Background(), blockCheckTimeout)
+	defer cancel()
+
+	txc, _ := pool.reorgOnNewHead(ctx, head)
+	m, r := txc.getLists()
+	pool.relay.NewHead(pool.head, m, r)
+	pool.homestead = pool.config.IsHomestead(head.Number)
+	pool.signer = types.MakeSigner(pool.config, head.Number)
+}
+
 // Stop stops the light transaction pool
 func (pool *TxPool) Stop() {
 	close(pool.quit)
diff --git a/light/txpool_test.go b/light/txpool_test.go
index 980c7c898..e93955511 100644
--- a/light/txpool_test.go
+++ b/light/txpool_test.go
@@ -17,6 +17,7 @@
 package light
 
 import (
+	"context"
 	"math"
 	"math/big"
 	"testing"
@@ -30,7 +31,6 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/pow"
-	"golang.org/x/net/context"
 )
 
 type testTxRelay struct {
@@ -107,10 +107,11 @@ func TestTxPool(t *testing.T) {
 	lightchain.SetValidator(bproc{})
 	txPermanent = 50
 	pool := NewTxPool(testChainConfig(), evmux, lightchain, relay)
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
 
 	for ii, block := range gchain {
 		i := ii + 1
-		ctx, _ := context.WithTimeout(context.Background(), 200*time.Millisecond)
 		s := sentTx(i - 1)
 		e := sentTx(i)
 		for i := s; i < e; i++ {
diff --git a/light/vm_env.go b/light/vm_env.go
index ebd229de8..54aa12875 100644
--- a/light/vm_env.go
+++ b/light/vm_env.go
@@ -17,12 +17,12 @@
 package light
 
 import (
+	"context"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
-	"golang.org/x/net/context"
 )
 
 // VMState is a wrapper for the light state that holds the actual context and