From 8ed0f4b854272b5369175ae2e3d9979cf11ddf54 Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Sun, 8 Mar 2015 14:10:02 -0700
Subject: [PATCH 1/2] respect contexts in a more timely manner

---
 exchange/bitswap/bitswap.go | 53 ++++++++++++++++++++++++++++---------
 1 file changed, 40 insertions(+), 13 deletions(-)

diff --git a/exchange/bitswap/bitswap.go b/exchange/bitswap/bitswap.go
index 5271e23f1..91105b20a 100644
--- a/exchange/bitswap/bitswap.go
+++ b/exchange/bitswap/bitswap.go
@@ -227,21 +227,40 @@ func (bs *Bitswap) HasBlock(ctx context.Context, blk *blocks.Block) error {
 func (bs *Bitswap) sendWantlistMsgToPeers(ctx context.Context, m bsmsg.BitSwapMessage, peers <-chan peer.ID) error {
 	set := pset.New()
 	wg := sync.WaitGroup{}
-	for peerToQuery := range peers {
 
-		if !set.TryAdd(peerToQuery) { //Do once per peer
-			continue
-		}
-
-		wg.Add(1)
-		go func(p peer.ID) {
-			defer wg.Done()
-			if err := bs.send(ctx, p, m); err != nil {
-				log.Debug(err) // TODO remove if too verbose
+loop:
+	for {
+		select {
+		case peerToQuery, ok := <-peers:
+			if !ok {
+				break loop
 			}
-		}(peerToQuery)
+
+			if !set.TryAdd(peerToQuery) { //Do once per peer
+				continue
+			}
+
+			wg.Add(1)
+			go func(p peer.ID) {
+				defer wg.Done()
+				if err := bs.send(ctx, p, m); err != nil {
+					log.Debug(err) // TODO remove if too verbose
+				}
+			}(peerToQuery)
+		case <-ctx.Done():
+			return nil
+		}
+	}
+	done := make(chan struct{})
+	go func() {
+		wg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-ctx.Done():
 	}
-	wg.Wait()
 	return nil
 }
 
@@ -385,7 +404,15 @@ func (bs *Bitswap) wantNewBlocks(ctx context.Context, bkeys []u.Key) {
 			}
 		}(p)
 	}
-	wg.Wait()
+	done := make(chan struct{})
+	go func() {
+		wg.Wait()
+		close(done)
+	}()
+	select {
+	case <-done:
+	case <-ctx.Done():
+	}
 }
 
 func (bs *Bitswap) ReceiveError(err error) {

From 5eb08c44736b920cfffc8560a501071098007fd3 Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Mon, 9 Mar 2015 00:03:59 -0700
Subject: [PATCH 2/2] add warning comment about possibly leaked goroutines

---
 exchange/bitswap/bitswap.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/exchange/bitswap/bitswap.go b/exchange/bitswap/bitswap.go
index 91105b20a..649b3cc48 100644
--- a/exchange/bitswap/bitswap.go
+++ b/exchange/bitswap/bitswap.go
@@ -260,6 +260,9 @@ loop:
 	select {
 	case <-done:
 	case <-ctx.Done():
+		// NB: we may be abandoning goroutines here before they complete
+		// this shouldnt be an issue because they will complete soon anyways
+		// we just don't want their being slow to impact bitswap transfer speeds
 	}
 	return nil
 }
@@ -412,6 +415,9 @@ func (bs *Bitswap) wantNewBlocks(ctx context.Context, bkeys []u.Key) {
 	select {
 	case <-done:
 	case <-ctx.Done():
+		// NB: we may be abandoning goroutines here before they complete
+		// this shouldnt be an issue because they will complete soon anyways
+		// we just don't want their being slow to impact bitswap transfer speeds
 	}
 }