From 9c66f65410afa87a44d4bd2a455dd246ab626760 Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Thu, 26 Feb 2015 10:12:21 -0800
Subject: [PATCH 1/2] make wantlist updates to connected peers happen async,
 dramatically improves performance between connected nodes

---
 exchange/bitswap/bitswap.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/exchange/bitswap/bitswap.go b/exchange/bitswap/bitswap.go
index 500817b0a..1a4ec73cf 100644
--- a/exchange/bitswap/bitswap.go
+++ b/exchange/bitswap/bitswap.go
@@ -369,10 +369,12 @@ func (bs *bitswap) wantNewBlocks(ctx context.Context, bkeys []u.Key) {
 		message.AddEntry(k, kMaxPriority-i)
 	}
 	for _, p := range bs.engine.Peers() {
-		err := bs.send(ctx, p, message)
-		if err != nil {
-			log.Debugf("Error sending message: %s", err)
-		}
+		go func(p peer.ID) {
+			err := bs.send(ctx, p, message)
+			if err != nil {
+				log.Debugf("Error sending message: %s", err)
+			}
+		}(p)
 	}
 }
 

From 8256b180588bfd9a8286b9416b5aafb3624c10ec Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Thu, 26 Feb 2015 16:43:18 -0800
Subject: [PATCH 2/2] make sure not to orphan any extra goroutines

---
 exchange/bitswap/bitswap.go |  5 +++++
 exchange/bitswap/workers.go | 10 +++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/exchange/bitswap/bitswap.go b/exchange/bitswap/bitswap.go
index 1a4ec73cf..5508f66e3 100644
--- a/exchange/bitswap/bitswap.go
+++ b/exchange/bitswap/bitswap.go
@@ -368,14 +368,19 @@ func (bs *bitswap) wantNewBlocks(ctx context.Context, bkeys []u.Key) {
 	for i, k := range bkeys {
 		message.AddEntry(k, kMaxPriority-i)
 	}
+
+	wg := sync.WaitGroup{}
 	for _, p := range bs.engine.Peers() {
+		wg.Add(1)
 		go func(p peer.ID) {
+			defer wg.Done()
 			err := bs.send(ctx, p, message)
 			if err != nil {
 				log.Debugf("Error sending message: %s", err)
 			}
 		}(p)
 	}
+	wg.Wait()
 }
 
 func (bs *bitswap) ReceiveError(err error) {
diff --git a/exchange/bitswap/workers.go b/exchange/bitswap/workers.go
index 8239fced3..3753edb62 100644
--- a/exchange/bitswap/workers.go
+++ b/exchange/bitswap/workers.go
@@ -90,7 +90,11 @@ func (bs *bitswap) clientWorker(parent context.Context) {
 				bs.wantlist.Add(k, kMaxPriority-i)
 			}
 
-			bs.wantNewBlocks(req.ctx, keys)
+			done := make(chan struct{})
+			go func() {
+				bs.wantNewBlocks(req.ctx, keys)
+				close(done)
+			}()
 
 			// NB: Optimization. Assumes that providers of key[0] are likely to
 			// be able to provide for all keys. This currently holds true in most
@@ -101,6 +105,10 @@ func (bs *bitswap) clientWorker(parent context.Context) {
 			if err != nil {
 				log.Debugf("error sending wantlist: %s", err)
 			}
+
+			// Wait for wantNewBlocks to finish
+			<-done
+
 		case <-parent.Done():
 			return
 		}