vendor: update buildkit to master@8b7bcb900d3c

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/google.golang.org/grpc/internal/transport/controlbuf.go

@@ -191,7 +191,7 @@ type goAway struct {
 	code      http2.ErrCode
 	debugData []byte
 	headsUp   bool
-	closeConn bool
+	closeConn error // if set, loopyWriter will exit, resulting in conn closure
 }
 
 func (*goAway) isTransportResponseFrame() bool { return false }
@@ -209,6 +209,14 @@ type outFlowControlSizeRequest struct {
 
 func (*outFlowControlSizeRequest) isTransportResponseFrame() bool { return false }
 
+// closeConnection is an instruction to tell the loopy writer to flush the
+// framer and exit, which will cause the transport's connection to be closed
+// (by the client or server).  The transport itself will close after the reader
+// encounters the EOF caused by the connection closure.
+type closeConnection struct{}
+
+func (closeConnection) isTransportResponseFrame() bool { return false }
+
 type outStreamState int
 
 const (
@@ -408,7 +416,7 @@ func (c *controlBuffer) get(block bool) (interface{}, error) {
 		select {
 		case <-c.ch:
 		case <-c.done:
-			return nil, ErrConnClosing
+			return nil, errors.New("transport closed by client")
 		}
 	}
 }
@@ -519,18 +527,9 @@ const minBatchSize = 1000
 // As an optimization, to increase the batch size for each flush, loopy yields the processor, once
 // if the batch size is too low to give stream goroutines a chance to fill it up.
 func (l *loopyWriter) run() (err error) {
-	defer func() {
-		if err == ErrConnClosing {
-			// Don't log ErrConnClosing as error since it happens
-			// 1. When the connection is closed by some other known issue.
-			// 2. User closed the connection.
-			// 3. A graceful close of connection.
-			if logger.V(logLevel) {
-				logger.Infof("transport: loopyWriter.run returning. %v", err)
-			}
-			err = nil
-		}
-	}()
+	// Always flush the writer before exiting in case there are pending frames
+	// to be sent.
+	defer l.framer.writer.Flush()
 	for {
 		it, err := l.cbuf.get(true)
 		if err != nil {
@@ -574,7 +573,6 @@ func (l *loopyWriter) run() (err error) {
 			}
 			l.framer.writer.Flush()
 			break hasdata
-
 		}
 	}
 }
@@ -655,19 +653,20 @@ func (l *loopyWriter) headerHandler(h *headerFrame) error {
 		itl:   &itemList{},
 		wq:    h.wq,
 	}
-	str.itl.enqueue(h)
-	return l.originateStream(str)
+	return l.originateStream(str, h)
 }
 
-func (l *loopyWriter) originateStream(str *outStream) error {
-	hdr := str.itl.dequeue().(*headerFrame)
-	if err := hdr.initStream(str.id); err != nil {
-		if err == ErrConnClosing {
-			return err
-		}
-		// Other errors(errStreamDrain) need not close transport.
+func (l *loopyWriter) originateStream(str *outStream, hdr *headerFrame) error {
+	// l.draining is set when handling GoAway. In which case, we want to avoid
+	// creating new streams.
+	if l.draining {
+		// TODO: provide a better error with the reason we are in draining.
+		hdr.onOrphaned(errStreamDrain)
 		return nil
 	}
+	if err := hdr.initStream(str.id); err != nil {
+		return err
+	}
 	if err := l.writeHeader(str.id, hdr.endStream, hdr.hf, hdr.onWrite); err != nil {
 		return err
 	}
@@ -763,8 +762,8 @@ func (l *loopyWriter) cleanupStreamHandler(c *cleanupStream) error {
 			return err
 		}
 	}
-	if l.side == clientSide && l.draining && len(l.estdStreams) == 0 {
-		return ErrConnClosing
+	if l.draining && len(l.estdStreams) == 0 {
+		return errors.New("finished processing active streams while in draining mode")
 	}
 	return nil
 }
@@ -799,7 +798,7 @@ func (l *loopyWriter) incomingGoAwayHandler(*incomingGoAway) error {
 	if l.side == clientSide {
 		l.draining = true
 		if len(l.estdStreams) == 0 {
-			return ErrConnClosing
+			return errors.New("received GOAWAY with no active streams")
 		}
 	}
 	return nil
@@ -817,6 +816,13 @@ func (l *loopyWriter) goAwayHandler(g *goAway) error {
 	return nil
 }
 
+func (l *loopyWriter) closeConnectionHandler() error {
+	// Exit loopyWriter entirely by returning an error here.  This will lead to
+	// the transport closing the connection, and, ultimately, transport
+	// closure.
+	return ErrConnClosing
+}
+
 func (l *loopyWriter) handle(i interface{}) error {
 	switch i := i.(type) {
 	case *incomingWindowUpdate:
@@ -845,6 +851,8 @@ func (l *loopyWriter) handle(i interface{}) error {
 		return l.goAwayHandler(i)
 	case *outFlowControlSizeRequest:
 		return l.outFlowControlSizeRequestHandler(i)
+	case closeConnection:
+		return l.closeConnectionHandler()
 	default:
 		return fmt.Errorf("transport: unknown control message type %T", i)
 	}