refac(exchange) replace timeout -> context in API

blockservice/blockservice.go

@@ -4,12 +4,13 @@ import (
 	"fmt"
 	"time"
 
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/datastore.go"
+	mh "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multihash"
+
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	exchange "github.com/jbenet/go-ipfs/exchange"
 	u "github.com/jbenet/go-ipfs/util"
-
-	mh "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-multihash"
 )
 
 // BlockService is a block datastore.
@@ -65,7 +66,8 @@ func (s *BlockService) GetBlock(k u.Key) (*blocks.Block, error) {
 		}, nil
 	} else if err == ds.ErrNotFound && s.Remote != nil {
 		u.DOut("Blockservice: Searching bitswap.\n")
-		blk, err := s.Remote.Block(k, time.Second*5)
+		ctx, _ := context.WithTimeout(context.TODO(), 5*time.Second)
+		blk, err := s.Remote.Block(ctx, k)
 		if err != nil {
 			return nil, err
 		}

exchange/bitswap/bitswap.go

@@ -2,7 +2,6 @@ package bitswap
 
 import (
 	"errors"
-	"time"
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/datastore.go"
@@ -65,18 +64,14 @@ type bitswap struct {
 	strategy strategy.Strategy
 }
 
-// GetBlock attempts to retrieve a particular block from peers, within timeout.
-func (bs *bitswap) Block(k u.Key, timeout time.Duration) (
+// GetBlock attempts to retrieve a particular block from peers within the
+// deadline enforced by the context
+func (bs *bitswap) Block(ctx context.Context, k u.Key) (
 	*blocks.Block, error) {
-	ctx, _ := context.WithTimeout(context.Background(), timeout)
 
-	// TODO replace timeout with ctx in routing interface
-	begin := time.Now()
-	tleft := timeout - time.Now().Sub(begin)
 	provs_ch := bs.routing.FindProvidersAsync(ctx, k, 20)
 
 	blockChannel := make(chan blocks.Block)
-	after := time.After(tleft)
 
 	// TODO: when the data is received, shut down this for loop ASAP
 	go func() {
@@ -98,8 +93,8 @@ func (bs *bitswap) Block(k u.Key, timeout time.Duration) (
 	case block := <-blockChannel:
 		close(blockChannel)
 		return &block, nil
-	case <-after:
-		return nil, u.ErrTimeout
+	case <-ctx.Done():
+		return nil, ctx.Err()
 	}
 }
 

exchange/bitswap/offline.go

@@ -2,7 +2,8 @@ package bitswap
 
 import (
 	"errors"
-	"time"
+
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	exchange "github.com/jbenet/go-ipfs/exchange"
@@ -21,7 +22,7 @@ type offlineExchange struct {
 // Block returns nil to signal that a block could not be retrieved for the
 // given key.
 // NB: This function may return before the timeout expires.
-func (_ *offlineExchange) Block(k u.Key, timeout time.Duration) (*blocks.Block, error) {
+func (_ *offlineExchange) Block(context.Context, u.Key) (*blocks.Block, error) {
 	return nil, errors.New("Block unavailable. Operating in offline mode")
 }
 

exchange/bitswap/offline_test.go

@@ -2,7 +2,8 @@ package bitswap
 
 import (
 	"testing"
-	"time"
+
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 
 	u "github.com/jbenet/go-ipfs/util"
 	testutil "github.com/jbenet/go-ipfs/util/testutil"
@@ -10,7 +11,7 @@ import (
 
 func TestBlockReturnsErr(t *testing.T) {
 	off := NewOfflineExchange()
-	_, err := off.Block(u.Key("foo"), time.Second)
+	_, err := off.Block(context.TODO(), u.Key("foo"))
 	if err != nil {
 		return // as desired
 	}

exchange/interface.go

 package bitswap
 
 import (
-	"time"
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 
 	blocks "github.com/jbenet/go-ipfs/blocks"
 	u "github.com/jbenet/go-ipfs/util"
@@ -13,7 +13,7 @@ type Interface interface {
 
 	// Block returns the block associated with a given key.
 	// TODO(brian): pass a context instead of a timeout
-	Block(k u.Key, timeout time.Duration) (*blocks.Block, error)
+	Block(context.Context, u.Key) (*blocks.Block, error)
 
 	// HasBlock asserts the existence of this block
 	// TODO(brian): rename -> HasBlock