Merge pull request ipfs/go-bitswap#369 from ipfs/fix/over-allocated-ctx

fix: avoid calling ctx.SetDeadline() every time we send a message

This commit was moved from ipfs/go-bitswap@f4b63ee

bitswap/network/ipfs_impl.go

@@ -103,11 +103,14 @@ func (s *streamMessageSender) Connect(ctx context.Context) (network.Stream, erro
 		return s.stream, nil
 	}
 
-	if err := s.bsnet.ConnectTo(ctx, s.to); err != nil {
+	tctx, cancel := context.WithTimeout(ctx, s.opts.SendTimeout)
+	defer cancel()
+
+	if err := s.bsnet.ConnectTo(tctx, s.to); err != nil {
 		return nil, err
 	}
 
-	stream, err := s.bsnet.newStreamToPeer(ctx, s.to)
+	stream, err := s.bsnet.newStreamToPeer(tctx, s.to)
 	if err != nil {
 		return nil, err
 	}
@@ -139,25 +142,20 @@ func (s *streamMessageSender) SupportsHave() bool {
 
 // Send a message to the peer, attempting multiple times
 func (s *streamMessageSender) SendMsg(ctx context.Context, msg bsmsg.BitSwapMessage) error {
-	return s.multiAttempt(ctx, func(fnctx context.Context) error {
-		return s.send(fnctx, msg)
+	return s.multiAttempt(ctx, func() error {
+		return s.send(ctx, msg)
 	})
 }
 
 // Perform a function with multiple attempts, and a timeout
-func (s *streamMessageSender) multiAttempt(ctx context.Context, fn func(context.Context) error) error {
+func (s *streamMessageSender) multiAttempt(ctx context.Context, fn func() error) error {
 	// Try to call the function repeatedly
 	var err error
 	for i := 0; i < s.opts.MaxRetries; i++ {
-		deadline := time.Now().Add(s.opts.SendTimeout)
-		sndctx, cancel := context.WithDeadline(ctx, deadline)
-
-		if err = fn(sndctx); err == nil {
-			cancel()
+		if err = fn(); err == nil {
 			// Attempt was successful
 			return nil
 		}
-		cancel()
 
 		// Attempt failed
 
@@ -196,13 +194,18 @@ func (s *streamMessageSender) multiAttempt(ctx context.Context, fn func(context.
 
 // Send a message to the peer
 func (s *streamMessageSender) send(ctx context.Context, msg bsmsg.BitSwapMessage) error {
+	start := time.Now()
 	stream, err := s.Connect(ctx)
 	if err != nil {
 		log.Infof("failed to open stream to %s: %s", s.to, err)
 		return err
 	}
 
-	if err = s.bsnet.msgToStream(ctx, stream, msg); err != nil {
+	// The send timeout includes the time required to connect
+	// (although usually we will already have connected - we only need to
+	// connect after a failed attempt to send)
+	timeout := s.opts.SendTimeout - time.Since(start)
+	if err = s.bsnet.msgToStream(ctx, stream, msg, timeout); err != nil {
 		log.Infof("failed to send message to %s: %s", s.to, err)
 		return err
 	}
@@ -234,9 +237,9 @@ func (bsnet *impl) SupportsHave(proto protocol.ID) bool {
 	return true
 }
 
-func (bsnet *impl) msgToStream(ctx context.Context, s network.Stream, msg bsmsg.BitSwapMessage) error {
-	deadline := time.Now().Add(sendMessageTimeout)
-	if dl, ok := ctx.Deadline(); ok {
+func (bsnet *impl) msgToStream(ctx context.Context, s network.Stream, msg bsmsg.BitSwapMessage, timeout time.Duration) error {
+	deadline := time.Now().Add(timeout)
+	if dl, ok := ctx.Deadline(); ok && dl.Before(deadline) {
 		deadline = dl
 	}
 
@@ -277,8 +280,8 @@ func (bsnet *impl) NewMessageSender(ctx context.Context, p peer.ID, opts *Messag
 		opts:  opts,
 	}
 
-	err := sender.multiAttempt(ctx, func(fnctx context.Context) error {
-		_, err := sender.Connect(fnctx)
+	err := sender.multiAttempt(ctx, func() error {
+		_, err := sender.Connect(ctx)
 		return err
 	})
 
@@ -313,7 +316,7 @@ func (bsnet *impl) SendMessage(
 		return err
 	}
 
-	if err = bsnet.msgToStream(ctx, s, outgoing); err != nil {
+	if err = bsnet.msgToStream(ctx, s, outgoing, sendMessageTimeout); err != nil {
 		_ = s.Reset()
 		return err
 	}