vendor: update buildkit to 8effd45b

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

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

@@ -857,38 +857,45 @@ func (l *loopyWriter) processData() (bool, error) {
 		return false, nil
 	}
 	var (
-		idx int
 		buf []byte
 	)
-	if len(dataItem.h) != 0 { // data header has not been written out yet.
-		buf = dataItem.h
-	} else {
-		idx = 1
-		buf = dataItem.d
-	}
-	size := http2MaxFrameLen
-	if len(buf) < size {
-		size = len(buf)
-	}
+	// Figure out the maximum size we can send
+	maxSize := http2MaxFrameLen
 	if strQuota := int(l.oiws) - str.bytesOutStanding; strQuota <= 0 { // stream-level flow control.
 		str.state = waitingOnStreamQuota
 		return false, nil
-	} else if strQuota < size {
-		size = strQuota
+	} else if maxSize > strQuota {
+		maxSize = strQuota
+	}
+	if maxSize > int(l.sendQuota) { // connection-level flow control.
+		maxSize = int(l.sendQuota)
+	}
+	// Compute how much of the header and data we can send within quota and max frame length
+	hSize := min(maxSize, len(dataItem.h))
+	dSize := min(maxSize-hSize, len(dataItem.d))
+	if hSize != 0 {
+		if dSize == 0 {
+			buf = dataItem.h
+		} else {
+			// We can add some data to grpc message header to distribute bytes more equally across frames.
+			// Copy on the stack to avoid generating garbage
+			var localBuf [http2MaxFrameLen]byte
+			copy(localBuf[:hSize], dataItem.h)
+			copy(localBuf[hSize:], dataItem.d[:dSize])
+			buf = localBuf[:hSize+dSize]
+		}
+	} else {
+		buf = dataItem.d
 	}
 
-	if l.sendQuota < uint32(size) { // connection-level flow control.
-		size = int(l.sendQuota)
-	}
+	size := hSize + dSize
+
 	// Now that outgoing flow controls are checked we can replenish str's write quota
 	str.wq.replenish(size)
 	var endStream bool
 	// If this is the last data message on this stream and all of it can be written in this iteration.
-	if dataItem.endStream && size == len(buf) {
-		// buf contains either data or it contains header but data is empty.
-		if idx == 1 || len(dataItem.d) == 0 {
-			endStream = true
-		}
+	if dataItem.endStream && len(dataItem.h)+len(dataItem.d) <= size {
+		endStream = true
 	}
 	if dataItem.onEachWrite != nil {
 		dataItem.onEachWrite()
@@ -896,14 +903,10 @@ func (l *loopyWriter) processData() (bool, error) {
 	if err := l.framer.fr.WriteData(dataItem.streamID, endStream, buf[:size]); err != nil {
 		return false, err
 	}
-	buf = buf[size:]
 	str.bytesOutStanding += size
 	l.sendQuota -= uint32(size)
-	if idx == 0 {
-		dataItem.h = buf
-	} else {
-		dataItem.d = buf
-	}
+	dataItem.h = dataItem.h[hSize:]
+	dataItem.d = dataItem.d[dSize:]
 
 	if len(dataItem.h) == 0 && len(dataItem.d) == 0 { // All the data from that message was written out.
 		str.itl.dequeue()
@@ -924,3 +927,10 @@ func (l *loopyWriter) processData() (bool, error) {
 	}
 	return false, nil
 }
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}