refac(routing) replace timeout -> ctx

@jbenet oh hai there!

exchange/bitswap/bitswap.go

@@ -22,7 +22,7 @@ import (
 type Routing interface {
 	// FindProvidersAsync returns a channel of providers for the given key
 	// TODO replace with timeout with context
-	FindProvidersAsync(u.Key, int, time.Duration) <-chan *peer.Peer
+	FindProvidersAsync(context.Context, u.Key, int) <-chan *peer.Peer
 
 	// Provide provides the key to the network
 	Provide(key u.Key) error
@@ -74,7 +74,7 @@ func (bs *bitswap) Block(k u.Key, timeout time.Duration) (
 	// TODO replace timeout with ctx in routing interface
 	begin := time.Now()
 	tleft := timeout - time.Now().Sub(begin)
-	provs_ch := bs.routing.FindProvidersAsync(k, 20, timeout)
+	provs_ch := bs.routing.FindProvidersAsync(ctx, k, 20)
 
 	blockChannel := make(chan blocks.Block)
 	after := time.After(tleft)

routing/dht/routing.go

@@ -121,9 +121,7 @@ func (dht *IpfsDHT) Provide(key u.Key) error {
 }
 
 // FindProvidersAsync runs FindProviders and sends back results over a channel
-func (dht *IpfsDHT) FindProvidersAsync(key u.Key, count int, timeout time.Duration) <-chan *peer.Peer {
-	ctx, _ := context.WithTimeout(context.TODO(), timeout)
-
+func (dht *IpfsDHT) FindProvidersAsync(ctx context.Context, key u.Key, count int) <-chan *peer.Peer {
 	peerOut := make(chan *peer.Peer, count)
 	go func() {
 		ps := newPeerSet()

routing/routing.go

@@ -3,6 +3,8 @@ package routing
 import (
 	"time"
 
+	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
+
 	peer "github.com/jbenet/go-ipfs/peer"
 	u "github.com/jbenet/go-ipfs/util"
 )
@@ -10,7 +12,7 @@ import (
 // IpfsRouting is the routing module interface
 // It is implemented by things like DHTs, etc.
 type IpfsRouting interface {
-	FindProvidersAsync(u.Key, int, time.Duration) <-chan *peer.Peer
+	FindProvidersAsync(context.Context, u.Key, int) <-chan *peer.Peer
 
 	// Basic Put/Get