vendor: update buildkit to 2943a0838

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

vendor/golang.org/x/net/http2/transport.go

@@ -108,6 +108,19 @@ type Transport struct {
 	// waiting for their turn.
 	StrictMaxConcurrentStreams bool
 
+	// ReadIdleTimeout is the timeout after which a health check using ping
+	// frame will be carried out if no frame is received on the connection.
+	// Note that a ping response will is considered a received frame, so if
+	// there is no other traffic on the connection, the health check will
+	// be performed every ReadIdleTimeout interval.
+	// If zero, no health check is performed.
+	ReadIdleTimeout time.Duration
+
+	// PingTimeout is the timeout after which the connection will be closed
+	// if a response to Ping is not received.
+	// Defaults to 15s.
+	PingTimeout time.Duration
+
 	// t1, if non-nil, is the standard library Transport using
 	// this transport. Its settings are used (but not its
 	// RoundTrip method, etc).
@@ -131,6 +144,14 @@ func (t *Transport) disableCompression() bool {
 	return t.DisableCompression || (t.t1 != nil && t.t1.DisableCompression)
 }
 
+func (t *Transport) pingTimeout() time.Duration {
+	if t.PingTimeout == 0 {
+		return 15 * time.Second
+	}
+	return t.PingTimeout
+
+}
+
 // ConfigureTransport configures a net/http HTTP/1 Transport to use HTTP/2.
 // It returns an error if t1 has already been HTTP/2-enabled.
 func ConfigureTransport(t1 *http.Transport) error {
@@ -675,6 +696,20 @@ func (t *Transport) newClientConn(c net.Conn, singleUse bool) (*ClientConn, erro
 	return cc, nil
 }
 
+func (cc *ClientConn) healthCheck() {
+	pingTimeout := cc.t.pingTimeout()
+	// We don't need to periodically ping in the health check, because the readLoop of ClientConn will
+	// trigger the healthCheck again if there is no frame received.
+	ctx, cancel := context.WithTimeout(context.Background(), pingTimeout)
+	defer cancel()
+	err := cc.Ping(ctx)
+	if err != nil {
+		cc.closeForLostPing()
+		cc.t.connPool().MarkDead(cc)
+		return
+	}
+}
+
 func (cc *ClientConn) setGoAway(f *GoAwayFrame) {
 	cc.mu.Lock()
 	defer cc.mu.Unlock()
@@ -846,14 +881,12 @@ func (cc *ClientConn) sendGoAway() error {
 	return nil
 }
 
-// Close closes the client connection immediately.
-//
-// In-flight requests are interrupted. For a graceful shutdown, use Shutdown instead.
-func (cc *ClientConn) Close() error {
+// closes the client connection immediately. In-flight requests are interrupted.
+// err is sent to streams.
+func (cc *ClientConn) closeForError(err error) error {
 	cc.mu.Lock()
 	defer cc.cond.Broadcast()
 	defer cc.mu.Unlock()
-	err := errors.New("http2: client connection force closed via ClientConn.Close")
 	for id, cs := range cc.streams {
 		select {
 		case cs.resc <- resAndError{err: err}:
@@ -866,6 +899,20 @@ func (cc *ClientConn) Close() error {
 	return cc.tconn.Close()
 }
 
+// Close closes the client connection immediately.
+//
+// In-flight requests are interrupted. For a graceful shutdown, use Shutdown instead.
+func (cc *ClientConn) Close() error {
+	err := errors.New("http2: client connection force closed via ClientConn.Close")
+	return cc.closeForError(err)
+}
+
+// closes the client connection immediately. In-flight requests are interrupted.
+func (cc *ClientConn) closeForLostPing() error {
+	err := errors.New("http2: client connection lost")
+	return cc.closeForError(err)
+}
+
 const maxAllocFrameSize = 512 << 10
 
 // frameBuffer returns a scratch buffer suitable for writing DATA frames.
@@ -916,7 +963,7 @@ func commaSeparatedTrailers(req *http.Request) (string, error) {
 		k = http.CanonicalHeaderKey(k)
 		switch k {
 		case "Transfer-Encoding", "Trailer", "Content-Length":
-			return "", &badStringError{"invalid Trailer key", k}
+			return "", fmt.Errorf("invalid Trailer key %q", k)
 		}
 		keys = append(keys, k)
 	}
@@ -1394,13 +1441,6 @@ func (cs *clientStream) awaitFlowControl(maxBytes int) (taken int32, err error)
 	}
 }
 
-type badStringError struct {
-	what string
-	str  string
-}
-
-func (e *badStringError) Error() string { return fmt.Sprintf("%s %q", e.what, e.str) }
-
 // requires cc.mu be held.
 func (cc *ClientConn) encodeHeaders(req *http.Request, addGzipHeader bool, trailers string, contentLength int64) ([]byte, error) {
 	cc.hbuf.Reset()
@@ -1616,6 +1656,7 @@ func (cc *ClientConn) writeHeader(name, value string) {
 }
 
 type resAndError struct {
+	_   incomparable
 	res *http.Response
 	err error
 }
@@ -1663,6 +1704,7 @@ func (cc *ClientConn) streamByID(id uint32, andRemove bool) *clientStream {
 
 // clientConnReadLoop is the state owned by the clientConn's frame-reading readLoop.
 type clientConnReadLoop struct {
+	_             incomparable
 	cc            *ClientConn
 	closeWhenIdle bool
 }
@@ -1742,8 +1784,17 @@ func (rl *clientConnReadLoop) run() error {
 	rl.closeWhenIdle = cc.t.disableKeepAlives() || cc.singleUse
 	gotReply := false // ever saw a HEADERS reply
 	gotSettings := false
+	readIdleTimeout := cc.t.ReadIdleTimeout
+	var t *time.Timer
+	if readIdleTimeout != 0 {
+		t = time.AfterFunc(readIdleTimeout, cc.healthCheck)
+		defer t.Stop()
+	}
 	for {
 		f, err := cc.fr.ReadFrame()
+		if t != nil {
+			t.Reset(readIdleTimeout)
+		}
 		if err != nil {
 			cc.vlogf("http2: Transport readFrame error on conn %p: (%T) %v", cc, err, err)
 		}
@@ -1892,7 +1943,9 @@ func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFra
 		return nil, errors.New("malformed response from server: malformed non-numeric status pseudo header")
 	}
 
-	header := make(http.Header)
+	regularFields := f.RegularFields()
+	strs := make([]string, len(regularFields))
+	header := make(http.Header, len(regularFields))
 	res := &http.Response{
 		Proto:      "HTTP/2.0",
 		ProtoMajor: 2,
@@ -1900,7 +1953,7 @@ func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFra
 		StatusCode: statusCode,
 		Status:     status + " " + http.StatusText(statusCode),
 	}
-	for _, hf := range f.RegularFields() {
+	for _, hf := range regularFields {
 		key := http.CanonicalHeaderKey(hf.Name)
 		if key == "Trailer" {
 			t := res.Trailer
@@ -1912,7 +1965,18 @@ func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFra
 				t[http.CanonicalHeaderKey(v)] = nil
 			})
 		} else {
-			header[key] = append(header[key], hf.Value)
+			vv := header[key]
+			if vv == nil && len(strs) > 0 {
+				// More than likely this will be a single-element key.
+				// Most headers aren't multi-valued.
+				// Set the capacity on strs[0] to 1, so any future append
+				// won't extend the slice into the other strings.
+				vv, strs = strs[:1:1], strs[1:]
+				vv[0] = hf.Value
+				header[key] = vv
+			} else {
+				header[key] = append(vv, hf.Value)
+			}
 		}
 	}
 
@@ -2466,6 +2530,7 @@ func (rt erringRoundTripper) RoundTrip(*http.Request) (*http.Response, error) {
 // gzipReader wraps a response body so it can lazily
 // call gzip.NewReader on the first call to Read
 type gzipReader struct {
+	_    incomparable
 	body io.ReadCloser // underlying Response.Body
 	zr   *gzip.Reader  // lazily-initialized gzip reader
 	zerr error         // sticky error