Reuse timers instead of time.After in loops

Reusing a timer repeatedly results in less GC than time.After in each loop iteration.

Closes #122

bitswap/network/ipfs_impl.go

@@ -179,10 +179,13 @@ func (s *streamMessageSender) multiAttempt(ctx context.Context, fn func() error)
 			return err
 		}
 
+		timer := time.NewTimer(s.opts.SendErrorBackoff)
+		defer timer.Stop()
+
 		select {
 		case <-ctx.Done():
 			return ctx.Err()
-		case <-time.After(s.opts.SendErrorBackoff):
+		case <-timer.C:
 			// wait a short time in case disconnect notifications are still propagating
 			log.Infof("send message to %s failed but context was not Done: %s", s.to, err)
 		}

bootstrap/bootstrap.go

@@ -304,15 +304,19 @@ func peersConnect(ctx context.Context, ph host.Host, availablePeers []peer.AddrI
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 	go func() {
+		timer := time.NewTimer(time.Second)
+		defer timer.Stop()
+
 		for {
 			select {
 			case <-ctx.Done():
 				return
-			case <-time.After(1 * time.Second):
+			case <-timer.C:
 				if int(atomic.LoadUint64(&connected)) >= needed {
 					cancel()
 					return
 				}
+				timer.Reset(time.Second)
 			}
 		}
 	}()

mfs/repub.go

@@ -169,18 +169,27 @@ func (rp *Republisher) Run(lastPublished cid.Cid) {
 
 		// 2. If we have a value to publish, publish it now.
 		if toPublish.Defined() {
+			var timer *time.Timer
 			for {
 				err := rp.pubfunc(rp.ctx, toPublish)
 				if err == nil {
 					break
 				}
+
+				if timer == nil {
+					timer = time.NewTimer(rp.RetryTimeout)
+					defer timer.Stop()
+				} else {
+					timer.Reset(rp.RetryTimeout)
+				}
+
 				// Keep retrying until we succeed or we abort.
 				// TODO(steb): We could try pulling new values
 				// off `update` but that's not critical (and
 				// complicates this code a bit). We'll pull off
 				// a new value on the next loop through.
 				select {
-				case <-time.After(rp.RetryTimeout):
+				case <-timer.C:
 				case <-rp.ctx.Done():
 					return
 				}