From 8bacc6cdd991cc932671307e8b6dad4a83c9678f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ra=C3=BAl=20Kripalani?= <raul@protocol.ai>
Date: Tue, 19 Feb 2019 18:10:01 +0000
Subject: [PATCH 1/2] dialqueue: fix possible worker goroutine leak.

---
 dial_queue.go | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/dial_queue.go b/dial_queue.go
index 62fbf03e507..0315bb15f33 100644
--- a/dial_queue.go
+++ b/dial_queue.go
@@ -323,7 +323,14 @@ func (dq *dialQueue) worker() {
 			}
 			logger.Debugf("dialling %v took %dms (as observed by the dht subsystem).", p, time.Since(t)/time.Millisecond)
 			waiting := len(dq.waitingCh)
-			dq.out.EnqChan <- p
+
+			// by the time we're done dialling, it's possible that the context is closed, in which case there will
+			// be nobody listening on dq.out.EnqChan and we could block forever.
+			select {
+			case dq.out.EnqChan <- p:
+			case <-dq.ctx.Done():
+				return
+			}
 			if waiting > 0 {
 				// we have somebody to deliver this value to, so no need to shrink.
 				continue

From 4f0cf486fa2a8ccbce14dd047c1a18c0f50d7f4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ra=C3=BAl=20Kripalani?= <raul@protocol.ai>
Date: Tue, 19 Feb 2019 18:10:56 +0000
Subject: [PATCH 2/2] dialqueue: rename local var for clarity.

---
 dial_queue.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/dial_queue.go b/dial_queue.go
index 0315bb15f33..75cc703f64c 100644
--- a/dial_queue.go
+++ b/dial_queue.go
@@ -110,7 +110,7 @@ type waitingCh struct {
 // end up adding fuel to the fire. Since we have no deterministic way to detect this for now, we hard-limit concurrency
 // to config.maxParallelism.
 func newDialQueue(params *dqParams) (*dialQueue, error) {
-	sq := &dialQueue{
+	dq := &dialQueue{
 		dqParams:  params,
 		nWorkers:  params.config.minParallelism,
 		out:       queue.NewChanQueue(params.ctx, queue.NewXORDistancePQ(params.target)),
@@ -121,10 +121,10 @@ func newDialQueue(params *dqParams) (*dialQueue, error) {
 	}
 
 	for i := 0; i < int(params.config.minParallelism); i++ {
-		go sq.worker()
+		go dq.worker()
 	}
-	go sq.control()
-	return sq, nil
+	go dq.control()
+	return dq, nil
 }
 
 func (dq *dialQueue) control() {