peer/queue: close fix, and logging

p2p/peer/queue/sync.go

@@ -4,8 +4,11 @@ import (
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 
 	peer "github.com/jbenet/go-ipfs/p2p/peer"
+	eventlog "github.com/jbenet/go-ipfs/util/eventlog"
 )
 
+var log = eventlog.Logger("peerqueue")
+
 // ChanQueue makes any PeerQueue synchronizable through channels.
 type ChanQueue struct {
 	Queue   PeerQueue
@@ -21,6 +24,7 @@ func NewChanQueue(ctx context.Context, pq PeerQueue) *ChanQueue {
 }
 
 func (cq *ChanQueue) process(ctx context.Context) {
+	log := log.Prefix("<ChanQueue %p>", cq)
 
 	// construct the channels here to be able to use them bidirectionally
 	enqChan := make(chan peer.ID)
@@ -30,6 +34,8 @@ func (cq *ChanQueue) process(ctx context.Context) {
 	cq.DeqChan = deqChan
 
 	go func() {
+		log.Debug("processing")
+		defer log.Debug("closed")
 		defer close(deqChan)
 
 		var next peer.ID
@@ -38,11 +44,13 @@ func (cq *ChanQueue) process(ctx context.Context) {
 
 		for {
 			if cq.Queue.Len() == 0 {
+				// log.Debug("wait for enqueue")
 				select {
 				case next, more = <-enqChan:
 					if !more {
 						return
 					}
+					// log.Debug("got", next)
 
 				case <-ctx.Done():
 					return
@@ -50,19 +58,24 @@ func (cq *ChanQueue) process(ctx context.Context) {
 
 			} else {
 				next = cq.Queue.Dequeue()
+				// log.Debug("peek", next)
 			}
 
 			select {
 			case item, more = <-enqChan:
 				if !more {
-					return
+					if cq.Queue.Len() > 0 {
+						return // we're done done.
+					}
+					enqChan = nil // closed, so no use.
 				}
-
+				// log.Debug("got", item)
 				cq.Queue.Enqueue(item)
-				cq.Queue.Enqueue(next)
+				cq.Queue.Enqueue(next) // order may have changed.
 				next = ""
 
 			case deqChan <- next:
+				// log.Debug("dequeued", next)
 				next = ""
 
 			case <-ctx.Done():