rebase: bump google.golang.org/grpc from 1.65.0 to 1.66.0

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.65.0 to 1.66.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.65.0...v1.66.0)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

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

@@ -32,6 +32,7 @@ import (
 	"golang.org/x/net/http2/hpack"
 	"google.golang.org/grpc/internal/grpclog"
 	"google.golang.org/grpc/internal/grpcutil"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/status"
 )
 
@@ -148,9 +149,9 @@ type dataFrame struct {
 	streamID  uint32
 	endStream bool
 	h         []byte
-	d         []byte
+	reader    mem.Reader
 	// onEachWrite is called every time
-	// a part of d is written out.
+	// a part of data is written out.
 	onEachWrite func()
 }
 
@@ -289,18 +290,22 @@ func (l *outStreamList) dequeue() *outStream {
 }
 
 // controlBuffer is a way to pass information to loopy.
-// Information is passed as specific struct types called control frames.
-// A control frame not only represents data, messages or headers to be sent out
-// but can also be used to instruct loopy to update its internal state.
-// It shouldn't be confused with an HTTP2 frame, although some of the control frames
-// like dataFrame and headerFrame do go out on wire as HTTP2 frames.
+//
+// Information is passed as specific struct types called control frames. A
+// control frame not only represents data, messages or headers to be sent out
+// but can also be used to instruct loopy to update its internal state. It
+// shouldn't be confused with an HTTP2 frame, although some of the control
+// frames like dataFrame and headerFrame do go out on wire as HTTP2 frames.
 type controlBuffer struct {
-	ch              chan struct{}
-	done            <-chan struct{}
+	wakeupCh chan struct{}   // Unblocks readers waiting for something to read.
+	done     <-chan struct{} // Closed when the transport is done.
+
+	// Mutex guards all the fields below, except trfChan which can be read
+	// atomically without holding mu.
 	mu              sync.Mutex
-	consumerWaiting bool
-	list            *itemList
-	err             error
+	consumerWaiting bool      // True when readers are blocked waiting for new data.
+	closed          bool      // True when the controlbuf is finished.
+	list            *itemList // List of queued control frames.
 
 	// transportResponseFrames counts the number of queued items that represent
 	// the response of an action initiated by the peer.  trfChan is created
@@ -308,47 +313,59 @@ type controlBuffer struct {
 	// closed and nilled when transportResponseFrames drops below the
 	// threshold.  Both fields are protected by mu.
 	transportResponseFrames int
-	trfChan                 atomic.Value // chan struct{}
+	trfChan                 atomic.Pointer[chan struct{}]
 }
 
 func newControlBuffer(done <-chan struct{}) *controlBuffer {
 	return &controlBuffer{
-		ch:   make(chan struct{}, 1),
-		list: &itemList{},
-		done: done,
+		wakeupCh: make(chan struct{}, 1),
+		list:     &itemList{},
+		done:     done,
 	}
 }
 
-// throttle blocks if there are too many incomingSettings/cleanupStreams in the
-// controlbuf.
+// throttle blocks if there are too many frames in the control buf that
+// represent the response of an action initiated by the peer, like
+// incomingSettings cleanupStreams etc.
 func (c *controlBuffer) throttle() {
-	ch, _ := c.trfChan.Load().(chan struct{})
-	if ch != nil {
+	if ch := c.trfChan.Load(); ch != nil {
 		select {
-		case <-ch:
+		case <-(*ch):
 		case <-c.done:
 		}
 	}
 }
 
+// put adds an item to the controlbuf.
 func (c *controlBuffer) put(it cbItem) error {
 	_, err := c.executeAndPut(nil, it)
 	return err
 }
 
+// executeAndPut runs f, and if the return value is true, adds the given item to
+// the controlbuf. The item could be nil, in which case, this method simply
+// executes f and does not add the item to the controlbuf.
+//
+// The first return value indicates whether the item was successfully added to
+// the control buffer. A non-nil error, specifically ErrConnClosing, is returned
+// if the control buffer is already closed.
 func (c *controlBuffer) executeAndPut(f func() bool, it cbItem) (bool, error) {
-	var wakeUp bool
 	c.mu.Lock()
-	if c.err != nil {
-		c.mu.Unlock()
-		return false, c.err
+	defer c.mu.Unlock()
+
+	if c.closed {
+		return false, ErrConnClosing
 	}
 	if f != nil {
 		if !f() { // f wasn't successful
-			c.mu.Unlock()
 			return false, nil
 		}
 	}
+	if it == nil {
+		return true, nil
+	}
+
+	var wakeUp bool
 	if c.consumerWaiting {
 		wakeUp = true
 		c.consumerWaiting = false
@@ -359,98 +376,102 @@ func (c *controlBuffer) executeAndPut(f func() bool, it cbItem) (bool, error) {
 		if c.transportResponseFrames == maxQueuedTransportResponseFrames {
 			// We are adding the frame that puts us over the threshold; create
 			// a throttling channel.
-			c.trfChan.Store(make(chan struct{}))
+			ch := make(chan struct{})
+			c.trfChan.Store(&ch)
 		}
 	}
-	c.mu.Unlock()
 	if wakeUp {
 		select {
-		case c.ch <- struct{}{}:
+		case c.wakeupCh <- struct{}{}:
 		default:
 		}
 	}
 	return true, nil
 }
 
-// Note argument f should never be nil.
-func (c *controlBuffer) execute(f func(it any) bool, it any) (bool, error) {
-	c.mu.Lock()
-	if c.err != nil {
-		c.mu.Unlock()
-		return false, c.err
-	}
-	if !f(it) { // f wasn't successful
-		c.mu.Unlock()
-		return false, nil
-	}
-	c.mu.Unlock()
-	return true, nil
-}
-
+// get returns the next control frame from the control buffer. If block is true
+// **and** there are no control frames in the control buffer, the call blocks
+// until one of the conditions is met: there is a frame to return or the
+// transport is closed.
 func (c *controlBuffer) get(block bool) (any, error) {
 	for {
 		c.mu.Lock()
-		if c.err != nil {
+		frame, err := c.getOnceLocked()
+		if frame != nil || err != nil || !block {
+			// If we read a frame or an error, we can return to the caller. The
+			// call to getOnceLocked() returns a nil frame and a nil error if
+			// there is nothing to read, and in that case, if the caller asked
+			// us not to block, we can return now as well.
 			c.mu.Unlock()
-			return nil, c.err
-		}
-		if !c.list.isEmpty() {
-			h := c.list.dequeue().(cbItem)
-			if h.isTransportResponseFrame() {
-				if c.transportResponseFrames == maxQueuedTransportResponseFrames {
-					// We are removing the frame that put us over the
-					// threshold; close and clear the throttling channel.
-					ch := c.trfChan.Load().(chan struct{})
-					close(ch)
-					c.trfChan.Store((chan struct{})(nil))
-				}
-				c.transportResponseFrames--
-			}
-			c.mu.Unlock()
-			return h, nil
-		}
-		if !block {
-			c.mu.Unlock()
-			return nil, nil
+			return frame, err
 		}
 		c.consumerWaiting = true
 		c.mu.Unlock()
+
+		// Release the lock above and wait to be woken up.
 		select {
-		case <-c.ch:
+		case <-c.wakeupCh:
 		case <-c.done:
 			return nil, errors.New("transport closed by client")
 		}
 	}
 }
 
+// Callers must not use this method, but should instead use get().
+//
+// Caller must hold c.mu.
+func (c *controlBuffer) getOnceLocked() (any, error) {
+	if c.closed {
+		return false, ErrConnClosing
+	}
+	if c.list.isEmpty() {
+		return nil, nil
+	}
+	h := c.list.dequeue().(cbItem)
+	if h.isTransportResponseFrame() {
+		if c.transportResponseFrames == maxQueuedTransportResponseFrames {
+			// We are removing the frame that put us over the
+			// threshold; close and clear the throttling channel.
+			ch := c.trfChan.Swap(nil)
+			close(*ch)
+		}
+		c.transportResponseFrames--
+	}
+	return h, nil
+}
+
+// finish closes the control buffer, cleaning up any streams that have queued
+// header frames. Once this method returns, no more frames can be added to the
+// control buffer, and attempts to do so will return ErrConnClosing.
 func (c *controlBuffer) finish() {
 	c.mu.Lock()
-	if c.err != nil {
-		c.mu.Unlock()
+	defer c.mu.Unlock()
+
+	if c.closed {
 		return
 	}
-	c.err = ErrConnClosing
+	c.closed = true
 	// There may be headers for streams in the control buffer.
 	// These streams need to be cleaned out since the transport
 	// is still not aware of these yet.
 	for head := c.list.dequeueAll(); head != nil; head = head.next {
-		hdr, ok := head.it.(*headerFrame)
-		if !ok {
-			continue
-		}
-		if hdr.onOrphaned != nil { // It will be nil on the server-side.
-			hdr.onOrphaned(ErrConnClosing)
+		switch v := head.it.(type) {
+		case *headerFrame:
+			if v.onOrphaned != nil { // It will be nil on the server-side.
+				v.onOrphaned(ErrConnClosing)
+			}
+		case *dataFrame:
+			_ = v.reader.Close()
 		}
 	}
+
 	// In case throttle() is currently in flight, it needs to be unblocked.
 	// Otherwise, the transport may not close, since the transport is closed by
 	// the reader encountering the connection error.
-	ch, _ := c.trfChan.Load().(chan struct{})
+	ch := c.trfChan.Swap(nil)
 	if ch != nil {
-		close(ch)
+		close(*ch)
 	}
-	c.trfChan.Store((chan struct{})(nil))
-	c.mu.Unlock()
 }
 
 type side int
@@ -466,7 +487,7 @@ const (
 // stream maintains a queue of data frames; as loopy receives data frames
 // it gets added to the queue of the relevant stream.
 // Loopy goes over this list of active streams by processing one node every iteration,
-// thereby closely resemebling to a round-robin scheduling over all streams. While
+// thereby closely resembling a round-robin scheduling over all streams. While
 // processing a stream, loopy writes out data bytes from this stream capped by the min
 // of http2MaxFrameLen, connection-level flow control and stream-level flow control.
 type loopyWriter struct {
@@ -490,12 +511,13 @@ type loopyWriter struct {
 	draining      bool
 	conn          net.Conn
 	logger        *grpclog.PrefixLogger
+	bufferPool    mem.BufferPool
 
 	// Side-specific handlers
 	ssGoAwayHandler func(*goAway) (bool, error)
 }
 
-func newLoopyWriter(s side, fr *framer, cbuf *controlBuffer, bdpEst *bdpEstimator, conn net.Conn, logger *grpclog.PrefixLogger, goAwayHandler func(*goAway) (bool, error)) *loopyWriter {
+func newLoopyWriter(s side, fr *framer, cbuf *controlBuffer, bdpEst *bdpEstimator, conn net.Conn, logger *grpclog.PrefixLogger, goAwayHandler func(*goAway) (bool, error), bufferPool mem.BufferPool) *loopyWriter {
 	var buf bytes.Buffer
 	l := &loopyWriter{
 		side:            s,
@@ -511,6 +533,7 @@ func newLoopyWriter(s side, fr *framer, cbuf *controlBuffer, bdpEst *bdpEstimato
 		conn:            conn,
 		logger:          logger,
 		ssGoAwayHandler: goAwayHandler,
+		bufferPool:      bufferPool,
 	}
 	return l
 }
@@ -768,6 +791,11 @@ func (l *loopyWriter) cleanupStreamHandler(c *cleanupStream) error {
 		// not be established yet.
 		delete(l.estdStreams, c.streamID)
 		str.deleteSelf()
+		for head := str.itl.dequeueAll(); head != nil; head = head.next {
+			if df, ok := head.it.(*dataFrame); ok {
+				_ = df.reader.Close()
+			}
+		}
 	}
 	if c.rst { // If RST_STREAM needs to be sent.
 		if err := l.framer.fr.WriteRSTStream(c.streamID, c.rstCode); err != nil {
@@ -903,16 +931,18 @@ func (l *loopyWriter) processData() (bool, error) {
 	dataItem := str.itl.peek().(*dataFrame) // Peek at the first data item this stream.
 	// A data item is represented by a dataFrame, since it later translates into
 	// multiple HTTP2 data frames.
-	// Every dataFrame has two buffers; h that keeps grpc-message header and d that is actual data.
-	// As an optimization to keep wire traffic low, data from d is copied to h to make as big as the
-	// maximum possible HTTP2 frame size.
+	// Every dataFrame has two buffers; h that keeps grpc-message header and data
+	// that is the actual message. As an optimization to keep wire traffic low, data
+	// from data is copied to h to make as big as the maximum possible HTTP2 frame
+	// size.
 
-	if len(dataItem.h) == 0 && len(dataItem.d) == 0 { // Empty data frame
+	if len(dataItem.h) == 0 && dataItem.reader.Remaining() == 0 { // Empty data frame
 		// Client sends out empty data frame with endStream = true
 		if err := l.framer.fr.WriteData(dataItem.streamID, dataItem.endStream, nil); err != nil {
 			return false, err
 		}
 		str.itl.dequeue() // remove the empty data item from stream
+		_ = dataItem.reader.Close()
 		if str.itl.isEmpty() {
 			str.state = empty
 		} else if trailer, ok := str.itl.peek().(*headerFrame); ok { // the next item is trailers.
@@ -927,9 +957,7 @@ func (l *loopyWriter) processData() (bool, error) {
 		}
 		return false, nil
 	}
-	var (
-		buf []byte
-	)
+
 	// Figure out the maximum size we can send
 	maxSize := http2MaxFrameLen
 	if strQuota := int(l.oiws) - str.bytesOutStanding; strQuota <= 0 { // stream-level flow control.
@@ -943,43 +971,50 @@ func (l *loopyWriter) processData() (bool, error) {
 	}
 	// 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
-	}
-
+	dSize := min(maxSize-hSize, dataItem.reader.Remaining())
+	remainingBytes := len(dataItem.h) + dataItem.reader.Remaining() - hSize - dSize
 	size := hSize + dSize
 
+	var buf *[]byte
+
+	if hSize != 0 && dSize == 0 {
+		buf = &dataItem.h
+	} else {
+		// Note: this is only necessary because the http2.Framer does not support
+		// partially writing a frame, so the sequence must be materialized into a buffer.
+		// TODO: Revisit once https://github.com/golang/go/issues/66655 is addressed.
+		pool := l.bufferPool
+		if pool == nil {
+			// Note that this is only supposed to be nil in tests. Otherwise, stream is
+			// always initialized with a BufferPool.
+			pool = mem.DefaultBufferPool()
+		}
+		buf = pool.Get(size)
+		defer pool.Put(buf)
+
+		copy((*buf)[:hSize], dataItem.h)
+		_, _ = dataItem.reader.Read((*buf)[hSize:])
+	}
+
 	// 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 && len(dataItem.h)+len(dataItem.d) <= size {
+	if dataItem.endStream && remainingBytes == 0 {
 		endStream = true
 	}
 	if dataItem.onEachWrite != nil {
 		dataItem.onEachWrite()
 	}
-	if err := l.framer.fr.WriteData(dataItem.streamID, endStream, buf[:size]); err != nil {
+	if err := l.framer.fr.WriteData(dataItem.streamID, endStream, (*buf)[:size]); err != nil {
 		return false, err
 	}
 	str.bytesOutStanding += size
 	l.sendQuota -= uint32(size)
 	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.
+	if remainingBytes == 0 { // All the data from that message was written out.
+		_ = dataItem.reader.Close()
 		str.itl.dequeue()
 	}
 	if str.itl.isEmpty() {

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

@@ -24,7 +24,6 @@
 package transport
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -40,6 +39,7 @@ import (
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/internal/grpclog"
 	"google.golang.org/grpc/internal/grpcutil"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
 	"google.golang.org/grpc/stats"
@@ -50,7 +50,7 @@ import (
 // NewServerHandlerTransport returns a ServerTransport handling gRPC from
 // inside an http.Handler, or writes an HTTP error to w and returns an error.
 // It requires that the http Server supports HTTP/2.
-func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request, stats []stats.Handler) (ServerTransport, error) {
+func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request, stats []stats.Handler, bufferPool mem.BufferPool) (ServerTransport, error) {
 	if r.Method != http.MethodPost {
 		w.Header().Set("Allow", http.MethodPost)
 		msg := fmt.Sprintf("invalid gRPC request method %q", r.Method)
@@ -98,6 +98,7 @@ func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request, stats []s
 		contentType:    contentType,
 		contentSubtype: contentSubtype,
 		stats:          stats,
+		bufferPool:     bufferPool,
 	}
 	st.logger = prefixLoggerForServerHandlerTransport(st)
 
@@ -171,6 +172,8 @@ type serverHandlerTransport struct {
 
 	stats  []stats.Handler
 	logger *grpclog.PrefixLogger
+
+	bufferPool mem.BufferPool
 }
 
 func (ht *serverHandlerTransport) Close(err error) {
@@ -244,6 +247,7 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) erro
 		}
 
 		s.hdrMu.Lock()
+		defer s.hdrMu.Unlock()
 		if p := st.Proto(); p != nil && len(p.Details) > 0 {
 			delete(s.trailer, grpcStatusDetailsBinHeader)
 			stBytes, err := proto.Marshal(p)
@@ -268,7 +272,6 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) erro
 				}
 			}
 		}
-		s.hdrMu.Unlock()
 	})
 
 	if err == nil { // transport has not been closed
@@ -330,16 +333,28 @@ func (ht *serverHandlerTransport) writeCustomHeaders(s *Stream) {
 	s.hdrMu.Unlock()
 }
 
-func (ht *serverHandlerTransport) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+func (ht *serverHandlerTransport) Write(s *Stream, hdr []byte, data mem.BufferSlice, opts *Options) error {
+	// Always take a reference because otherwise there is no guarantee the data will
+	// be available after this function returns. This is what callers to Write
+	// expect.
+	data.Ref()
 	headersWritten := s.updateHeaderSent()
-	return ht.do(func() {
+	err := ht.do(func() {
+		defer data.Free()
 		if !headersWritten {
 			ht.writePendingHeaders(s)
 		}
 		ht.rw.Write(hdr)
-		ht.rw.Write(data)
+		for _, b := range data {
+			_, _ = ht.rw.Write(b.ReadOnlyData())
+		}
 		ht.rw.(http.Flusher).Flush()
 	})
+	if err != nil {
+		data.Free()
+		return err
+	}
+	return nil
 }
 
 func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
@@ -406,7 +421,7 @@ func (ht *serverHandlerTransport) HandleStreams(ctx context.Context, startStream
 		headerWireLength: 0, // won't have access to header wire length until golang/go#18997.
 	}
 	s.trReader = &transportReader{
-		reader:        &recvBufferReader{ctx: s.ctx, ctxDone: s.ctx.Done(), recv: s.buf, freeBuffer: func(*bytes.Buffer) {}},
+		reader:        &recvBufferReader{ctx: s.ctx, ctxDone: s.ctx.Done(), recv: s.buf},
 		windowHandler: func(int) {},
 	}
 
@@ -415,21 +430,19 @@ func (ht *serverHandlerTransport) HandleStreams(ctx context.Context, startStream
 	go func() {
 		defer close(readerDone)
 
-		// TODO: minimize garbage, optimize recvBuffer code/ownership
-		const readSize = 8196
-		for buf := make([]byte, readSize); ; {
-			n, err := req.Body.Read(buf)
+		for {
+			buf := ht.bufferPool.Get(http2MaxFrameLen)
+			n, err := req.Body.Read(*buf)
 			if n > 0 {
-				s.buf.put(recvMsg{buffer: bytes.NewBuffer(buf[:n:n])})
-				buf = buf[n:]
+				*buf = (*buf)[:n]
+				s.buf.put(recvMsg{buffer: mem.NewBuffer(buf, ht.bufferPool)})
+			} else {
+				ht.bufferPool.Put(buf)
 			}
 			if err != nil {
 				s.buf.put(recvMsg{err: mapRecvMsgError(err)})
 				return
 			}
-			if len(buf) == 0 {
-				buf = make([]byte, readSize)
-			}
 		}
 	}()
 

vendor/google.golang.org/grpc/internal/transport/http2_client.go

@@ -47,6 +47,7 @@ import (
 	isyscall "google.golang.org/grpc/internal/syscall"
 	"google.golang.org/grpc/internal/transport/networktype"
 	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
 	"google.golang.org/grpc/resolver"
@@ -59,6 +60,8 @@ import (
 // atomically.
 var clientConnectionCounter uint64
 
+var goAwayLoopyWriterTimeout = 5 * time.Second
+
 var metadataFromOutgoingContextRaw = internal.FromOutgoingContextRaw.(func(context.Context) (metadata.MD, [][]string, bool))
 
 // http2Client implements the ClientTransport interface with HTTP2.
@@ -144,7 +147,7 @@ type http2Client struct {
 
 	onClose func(GoAwayReason)
 
-	bufferPool *bufferPool
+	bufferPool mem.BufferPool
 
 	connectionID uint64
 	logger       *grpclog.PrefixLogger
@@ -229,7 +232,7 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		}
 	}(conn)
 
-	// The following defer and goroutine monitor the connectCtx for cancelation
+	// The following defer and goroutine monitor the connectCtx for cancellation
 	// and deadline.  On context expiration, the connection is hard closed and
 	// this function will naturally fail as a result.  Otherwise, the defer
 	// waits for the goroutine to exit to prevent the context from being
@@ -346,7 +349,7 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		streamQuota:           defaultMaxStreamsClient,
 		streamsQuotaAvailable: make(chan struct{}, 1),
 		keepaliveEnabled:      keepaliveEnabled,
-		bufferPool:            newBufferPool(),
+		bufferPool:            opts.BufferPool,
 		onClose:               onClose,
 	}
 	var czSecurity credentials.ChannelzSecurityValue
@@ -463,7 +466,7 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		return nil, err
 	}
 	go func() {
-		t.loopy = newLoopyWriter(clientSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger, t.outgoingGoAwayHandler)
+		t.loopy = newLoopyWriter(clientSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger, t.outgoingGoAwayHandler, t.bufferPool)
 		if err := t.loopy.run(); !isIOError(err) {
 			// Immediately close the connection, as the loopy writer returns
 			// when there are no more active streams and we were draining (the
@@ -504,7 +507,6 @@ func (t *http2Client) newStream(ctx context.Context, callHdr *CallHdr) *Stream {
 			closeStream: func(err error) {
 				t.CloseStream(s, err)
 			},
-			freeBuffer: t.bufferPool.put,
 		},
 		windowHandler: func(n int) {
 			t.updateWindow(s, uint32(n))
@@ -983,6 +985,7 @@ func (t *http2Client) closeStream(s *Stream, err error, rst bool, rstCode http2.
 // only once on a transport. Once it is called, the transport should not be
 // accessed anymore.
 func (t *http2Client) Close(err error) {
+	t.conn.SetWriteDeadline(time.Now().Add(time.Second * 10))
 	t.mu.Lock()
 	// Make sure we only close once.
 	if t.state == closing {
@@ -1006,10 +1009,20 @@ func (t *http2Client) Close(err error) {
 		t.kpDormancyCond.Signal()
 	}
 	t.mu.Unlock()
+
 	// Per HTTP/2 spec, a GOAWAY frame must be sent before closing the
-	// connection. See https://httpwg.org/specs/rfc7540.html#GOAWAY.
+	// connection. See https://httpwg.org/specs/rfc7540.html#GOAWAY. It
+	// also waits for loopyWriter to be closed with a timer to avoid the
+	// long blocking in case the connection is blackholed, i.e. TCP is
+	// just stuck.
 	t.controlBuf.put(&goAway{code: http2.ErrCodeNo, debugData: []byte("client transport shutdown"), closeConn: err})
-	<-t.writerDone
+	timer := time.NewTimer(goAwayLoopyWriterTimeout)
+	defer timer.Stop()
+	select {
+	case <-t.writerDone: // success
+	case <-timer.C:
+		t.logger.Infof("Failed to write a GOAWAY frame as part of connection close after %s. Giving up and closing the transport.", goAwayLoopyWriterTimeout)
+	}
 	t.cancel()
 	t.conn.Close()
 	channelz.RemoveEntry(t.channelz.ID)
@@ -1065,27 +1078,36 @@ func (t *http2Client) GracefulClose() {
 
 // Write formats the data into HTTP2 data frame(s) and sends it out. The caller
 // should proceed only if Write returns nil.
-func (t *http2Client) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+func (t *http2Client) Write(s *Stream, hdr []byte, data mem.BufferSlice, opts *Options) error {
+	reader := data.Reader()
+
 	if opts.Last {
 		// If it's the last message, update stream state.
 		if !s.compareAndSwapState(streamActive, streamWriteDone) {
+			_ = reader.Close()
 			return errStreamDone
 		}
 	} else if s.getState() != streamActive {
+		_ = reader.Close()
 		return errStreamDone
 	}
 	df := &dataFrame{
 		streamID:  s.id,
 		endStream: opts.Last,
 		h:         hdr,
-		d:         data,
+		reader:    reader,
 	}
-	if hdr != nil || data != nil { // If it's not an empty data frame, check quota.
-		if err := s.wq.get(int32(len(hdr) + len(data))); err != nil {
+	if hdr != nil || df.reader.Remaining() != 0 { // If it's not an empty data frame, check quota.
+		if err := s.wq.get(int32(len(hdr) + df.reader.Remaining())); err != nil {
+			_ = reader.Close()
 			return err
 		}
 	}
-	return t.controlBuf.put(df)
+	if err := t.controlBuf.put(df); err != nil {
+		_ = reader.Close()
+		return err
+	}
+	return nil
 }
 
 func (t *http2Client) getStream(f http2.Frame) *Stream {
@@ -1190,10 +1212,13 @@ func (t *http2Client) handleData(f *http2.DataFrame) {
 		// guarantee f.Data() is consumed before the arrival of next frame.
 		// Can this copy be eliminated?
 		if len(f.Data()) > 0 {
-			buffer := t.bufferPool.get()
-			buffer.Reset()
-			buffer.Write(f.Data())
-			s.write(recvMsg{buffer: buffer})
+			pool := t.bufferPool
+			if pool == nil {
+				// Note that this is only supposed to be nil in tests. Otherwise, stream is
+				// always initialized with a BufferPool.
+				pool = mem.DefaultBufferPool()
+			}
+			s.write(recvMsg{buffer: mem.Copy(f.Data(), pool)})
 		}
 	}
 	// The server has closed the stream without sending trailers.  Record that
@@ -1222,7 +1247,7 @@ func (t *http2Client) handleRSTStream(f *http2.RSTStreamFrame) {
 	if statusCode == codes.Canceled {
 		if d, ok := s.ctx.Deadline(); ok && !d.After(time.Now()) {
 			// Our deadline was already exceeded, and that was likely the cause
-			// of this cancelation.  Alter the status code accordingly.
+			// of this cancellation.  Alter the status code accordingly.
 			statusCode = codes.DeadlineExceeded
 		}
 	}
@@ -1307,7 +1332,7 @@ func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
 	id := f.LastStreamID
 	if id > 0 && id%2 == 0 {
 		t.mu.Unlock()
-		t.Close(connectionErrorf(true, nil, "received goaway with non-zero even-numbered numbered stream id: %v", id))
+		t.Close(connectionErrorf(true, nil, "received goaway with non-zero even-numbered stream id: %v", id))
 		return
 	}
 	// A client can receive multiple GoAways from the server (see

vendor/google.golang.org/grpc/internal/transport/http2_server.go

@@ -39,6 +39,7 @@ import (
 	"google.golang.org/grpc/internal/grpcutil"
 	"google.golang.org/grpc/internal/pretty"
 	"google.golang.org/grpc/internal/syscall"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/protobuf/proto"
 
 	"google.golang.org/grpc/codes"
@@ -119,7 +120,7 @@ type http2Server struct {
 
 	// Fields below are for channelz metric collection.
 	channelz   *channelz.Socket
-	bufferPool *bufferPool
+	bufferPool mem.BufferPool
 
 	connectionID uint64
 
@@ -261,7 +262,7 @@ func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport,
 		idle:              time.Now(),
 		kep:               kep,
 		initialWindowSize: iwz,
-		bufferPool:        newBufferPool(),
+		bufferPool:        config.BufferPool,
 	}
 	var czSecurity credentials.ChannelzSecurityValue
 	if au, ok := authInfo.(credentials.ChannelzSecurityInfo); ok {
@@ -330,7 +331,7 @@ func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport,
 	t.handleSettings(sf)
 
 	go func() {
-		t.loopy = newLoopyWriter(serverSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger, t.outgoingGoAwayHandler)
+		t.loopy = newLoopyWriter(serverSide, t.framer, t.controlBuf, t.bdpEst, t.conn, t.logger, t.outgoingGoAwayHandler, t.bufferPool)
 		err := t.loopy.run()
 		close(t.loopyWriterDone)
 		if !isIOError(err) {
@@ -613,10 +614,9 @@ func (t *http2Server) operateHeaders(ctx context.Context, frame *http2.MetaHeade
 	s.wq = newWriteQuota(defaultWriteQuota, s.ctxDone)
 	s.trReader = &transportReader{
 		reader: &recvBufferReader{
-			ctx:        s.ctx,
-			ctxDone:    s.ctxDone,
-			recv:       s.buf,
-			freeBuffer: t.bufferPool.put,
+			ctx:     s.ctx,
+			ctxDone: s.ctxDone,
+			recv:    s.buf,
 		},
 		windowHandler: func(n int) {
 			t.updateWindow(s, uint32(n))
@@ -813,10 +813,13 @@ func (t *http2Server) handleData(f *http2.DataFrame) {
 		// guarantee f.Data() is consumed before the arrival of next frame.
 		// Can this copy be eliminated?
 		if len(f.Data()) > 0 {
-			buffer := t.bufferPool.get()
-			buffer.Reset()
-			buffer.Write(f.Data())
-			s.write(recvMsg{buffer: buffer})
+			pool := t.bufferPool
+			if pool == nil {
+				// Note that this is only supposed to be nil in tests. Otherwise, stream is
+				// always initialized with a BufferPool.
+				pool = mem.DefaultBufferPool()
+			}
+			s.write(recvMsg{buffer: mem.Copy(f.Data(), pool)})
 		}
 	}
 	if f.StreamEnded() {
@@ -1089,7 +1092,9 @@ func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
 		onWrite:   t.setResetPingStrikes,
 	}
 
-	success, err := t.controlBuf.execute(t.checkForHeaderListSize, trailingHeader)
+	success, err := t.controlBuf.executeAndPut(func() bool {
+		return t.checkForHeaderListSize(trailingHeader)
+	}, nil)
 	if !success {
 		if err != nil {
 			return err
@@ -1112,27 +1117,37 @@ func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
 
 // Write converts the data into HTTP2 data frame and sends it out. Non-nil error
 // is returns if it fails (e.g., framing error, transport error).
-func (t *http2Server) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+func (t *http2Server) Write(s *Stream, hdr []byte, data mem.BufferSlice, opts *Options) error {
+	reader := data.Reader()
+
 	if !s.isHeaderSent() { // Headers haven't been written yet.
 		if err := t.WriteHeader(s, nil); err != nil {
+			_ = reader.Close()
 			return err
 		}
 	} else {
 		// Writing headers checks for this condition.
 		if s.getState() == streamDone {
+			_ = reader.Close()
 			return t.streamContextErr(s)
 		}
 	}
+
 	df := &dataFrame{
 		streamID:    s.id,
 		h:           hdr,
-		d:           data,
+		reader:      reader,
 		onEachWrite: t.setResetPingStrikes,
 	}
-	if err := s.wq.get(int32(len(hdr) + len(data))); err != nil {
+	if err := s.wq.get(int32(len(hdr) + df.reader.Remaining())); err != nil {
+		_ = reader.Close()
 		return t.streamContextErr(s)
 	}
-	return t.controlBuf.put(df)
+	if err := t.controlBuf.put(df); err != nil {
+		_ = reader.Close()
+		return err
+	}
+	return nil
 }
 
 // keepalive running in a separate goroutine does the following:

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

@@ -317,28 +317,32 @@ func newBufWriter(conn net.Conn, batchSize int, pool *sync.Pool) *bufWriter {
 	return w
 }
 
-func (w *bufWriter) Write(b []byte) (n int, err error) {
+func (w *bufWriter) Write(b []byte) (int, error) {
 	if w.err != nil {
 		return 0, w.err
 	}
 	if w.batchSize == 0 { // Buffer has been disabled.
-		n, err = w.conn.Write(b)
+		n, err := w.conn.Write(b)
 		return n, toIOError(err)
 	}
 	if w.buf == nil {
 		b := w.pool.Get().(*[]byte)
 		w.buf = *b
 	}
+	written := 0
 	for len(b) > 0 {
-		nn := copy(w.buf[w.offset:], b)
-		b = b[nn:]
-		w.offset += nn
-		n += nn
-		if w.offset >= w.batchSize {
-			err = w.flushKeepBuffer()
+		copied := copy(w.buf[w.offset:], b)
+		b = b[copied:]
+		written += copied
+		w.offset += copied
+		if w.offset < w.batchSize {
+			continue
+		}
+		if err := w.flushKeepBuffer(); err != nil {
+			return written, err
 		}
 	}
-	return n, err
+	return written, nil
 }
 
 func (w *bufWriter) Flush() error {

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

@@ -107,8 +107,14 @@ func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr stri
 		}
 		return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
 	}
-
-	return &bufConn{Conn: conn, r: r}, nil
+	// The buffer could contain extra bytes from the target server, so we can't
+	// discard it. However, in many cases where the server waits for the client
+	// to send the first message (e.g. when TLS is being used), the buffer will
+	// be empty, so we can avoid the overhead of reading through this buffer.
+	if r.Buffered() != 0 {
+		return &bufConn{Conn: conn, r: r}, nil
+	}
+	return conn, nil
 }
 
 // proxyDial dials, connecting to a proxy first if necessary. Checks if a proxy

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

@@ -22,7 +22,6 @@
 package transport
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -37,6 +36,7 @@ import (
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/internal/channelz"
 	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
 	"google.golang.org/grpc/resolver"
@@ -47,32 +47,10 @@ import (
 
 const logLevel = 2
 
-type bufferPool struct {
-	pool sync.Pool
-}
-
-func newBufferPool() *bufferPool {
-	return &bufferPool{
-		pool: sync.Pool{
-			New: func() any {
-				return new(bytes.Buffer)
-			},
-		},
-	}
-}
-
-func (p *bufferPool) get() *bytes.Buffer {
-	return p.pool.Get().(*bytes.Buffer)
-}
-
-func (p *bufferPool) put(b *bytes.Buffer) {
-	p.pool.Put(b)
-}
-
 // recvMsg represents the received msg from the transport. All transport
 // protocol specific info has been removed.
 type recvMsg struct {
-	buffer *bytes.Buffer
+	buffer mem.Buffer
 	// nil: received some data
 	// io.EOF: stream is completed. data is nil.
 	// other non-nil error: transport failure. data is nil.
@@ -102,6 +80,9 @@ func newRecvBuffer() *recvBuffer {
 func (b *recvBuffer) put(r recvMsg) {
 	b.mu.Lock()
 	if b.err != nil {
+		// drop the buffer on the floor. Since b.err is not nil, any subsequent reads
+		// will always return an error, making this buffer inaccessible.
+		r.buffer.Free()
 		b.mu.Unlock()
 		// An error had occurred earlier, don't accept more
 		// data or errors.
@@ -148,45 +129,70 @@ type recvBufferReader struct {
 	ctx         context.Context
 	ctxDone     <-chan struct{} // cache of ctx.Done() (for performance).
 	recv        *recvBuffer
-	last        *bytes.Buffer // Stores the remaining data in the previous calls.
+	last        mem.Buffer // Stores the remaining data in the previous calls.
 	err         error
-	freeBuffer  func(*bytes.Buffer)
 }
 
-// Read reads the next len(p) bytes from last. If last is drained, it tries to
-// read additional data from recv. It blocks if there no additional data available
-// in recv. If Read returns any non-nil error, it will continue to return that error.
-func (r *recvBufferReader) Read(p []byte) (n int, err error) {
+func (r *recvBufferReader) ReadHeader(header []byte) (n int, err error) {
 	if r.err != nil {
 		return 0, r.err
 	}
 	if r.last != nil {
-		// Read remaining data left in last call.
-		copied, _ := r.last.Read(p)
-		if r.last.Len() == 0 {
-			r.freeBuffer(r.last)
-			r.last = nil
-		}
-		return copied, nil
+		n, r.last = mem.ReadUnsafe(header, r.last)
+		return n, nil
 	}
 	if r.closeStream != nil {
-		n, r.err = r.readClient(p)
+		n, r.err = r.readHeaderClient(header)
 	} else {
-		n, r.err = r.read(p)
+		n, r.err = r.readHeader(header)
 	}
 	return n, r.err
 }
 
-func (r *recvBufferReader) read(p []byte) (n int, err error) {
+// Read reads the next n bytes from last. If last is drained, it tries to read
+// additional data from recv. It blocks if there no additional data available in
+// recv. If Read returns any non-nil error, it will continue to return that
+// error.
+func (r *recvBufferReader) Read(n int) (buf mem.Buffer, err error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	if r.last != nil {
+		buf = r.last
+		if r.last.Len() > n {
+			buf, r.last = mem.SplitUnsafe(buf, n)
+		} else {
+			r.last = nil
+		}
+		return buf, nil
+	}
+	if r.closeStream != nil {
+		buf, r.err = r.readClient(n)
+	} else {
+		buf, r.err = r.read(n)
+	}
+	return buf, r.err
+}
+
+func (r *recvBufferReader) readHeader(header []byte) (n int, err error) {
 	select {
 	case <-r.ctxDone:
 		return 0, ContextErr(r.ctx.Err())
 	case m := <-r.recv.get():
-		return r.readAdditional(m, p)
+		return r.readHeaderAdditional(m, header)
 	}
 }
 
-func (r *recvBufferReader) readClient(p []byte) (n int, err error) {
+func (r *recvBufferReader) read(n int) (buf mem.Buffer, err error) {
+	select {
+	case <-r.ctxDone:
+		return nil, ContextErr(r.ctx.Err())
+	case m := <-r.recv.get():
+		return r.readAdditional(m, n)
+	}
+}
+
+func (r *recvBufferReader) readHeaderClient(header []byte) (n int, err error) {
 	// If the context is canceled, then closes the stream with nil metadata.
 	// closeStream writes its error parameter to r.recv as a recvMsg.
 	// r.readAdditional acts on that message and returns the necessary error.
@@ -207,25 +213,67 @@ func (r *recvBufferReader) readClient(p []byte) (n int, err error) {
 		// faster.
 		r.closeStream(ContextErr(r.ctx.Err()))
 		m := <-r.recv.get()
-		return r.readAdditional(m, p)
+		return r.readHeaderAdditional(m, header)
 	case m := <-r.recv.get():
-		return r.readAdditional(m, p)
+		return r.readHeaderAdditional(m, header)
 	}
 }
 
-func (r *recvBufferReader) readAdditional(m recvMsg, p []byte) (n int, err error) {
+func (r *recvBufferReader) readClient(n int) (buf mem.Buffer, err error) {
+	// If the context is canceled, then closes the stream with nil metadata.
+	// closeStream writes its error parameter to r.recv as a recvMsg.
+	// r.readAdditional acts on that message and returns the necessary error.
+	select {
+	case <-r.ctxDone:
+		// Note that this adds the ctx error to the end of recv buffer, and
+		// reads from the head. This will delay the error until recv buffer is
+		// empty, thus will delay ctx cancellation in Recv().
+		//
+		// It's done this way to fix a race between ctx cancel and trailer. The
+		// race was, stream.Recv() may return ctx error if ctxDone wins the
+		// race, but stream.Trailer() may return a non-nil md because the stream
+		// was not marked as done when trailer is received. This closeStream
+		// call will mark stream as done, thus fix the race.
+		//
+		// TODO: delaying ctx error seems like a unnecessary side effect. What
+		// we really want is to mark the stream as done, and return ctx error
+		// faster.
+		r.closeStream(ContextErr(r.ctx.Err()))
+		m := <-r.recv.get()
+		return r.readAdditional(m, n)
+	case m := <-r.recv.get():
+		return r.readAdditional(m, n)
+	}
+}
+
+func (r *recvBufferReader) readHeaderAdditional(m recvMsg, header []byte) (n int, err error) {
 	r.recv.load()
 	if m.err != nil {
+		if m.buffer != nil {
+			m.buffer.Free()
+		}
 		return 0, m.err
 	}
-	copied, _ := m.buffer.Read(p)
-	if m.buffer.Len() == 0 {
-		r.freeBuffer(m.buffer)
-		r.last = nil
-	} else {
-		r.last = m.buffer
+
+	n, r.last = mem.ReadUnsafe(header, m.buffer)
+
+	return n, nil
+}
+
+func (r *recvBufferReader) readAdditional(m recvMsg, n int) (b mem.Buffer, err error) {
+	r.recv.load()
+	if m.err != nil {
+		if m.buffer != nil {
+			m.buffer.Free()
+		}
+		return nil, m.err
 	}
-	return copied, nil
+
+	if m.buffer.Len() > n {
+		m.buffer, r.last = mem.SplitUnsafe(m.buffer, n)
+	}
+
+	return m.buffer, nil
 }
 
 type streamState uint32
@@ -241,7 +289,7 @@ const (
 type Stream struct {
 	id           uint32
 	st           ServerTransport    // nil for client side Stream
-	ct           *http2Client       // nil for server side Stream
+	ct           ClientTransport    // nil for server side Stream
 	ctx          context.Context    // the associated context of the stream
 	cancel       context.CancelFunc // always nil for client side Stream
 	done         chan struct{}      // closed at the end of stream to unblock writers. On the client side.
@@ -251,7 +299,7 @@ type Stream struct {
 	recvCompress string
 	sendCompress string
 	buf          *recvBuffer
-	trReader     io.Reader
+	trReader     *transportReader
 	fc           *inFlow
 	wq           *writeQuota
 
@@ -408,7 +456,7 @@ func (s *Stream) TrailersOnly() bool {
 	return s.noHeaders
 }
 
-// Trailer returns the cached trailer metedata. Note that if it is not called
+// Trailer returns the cached trailer metadata. Note that if it is not called
 // after the entire stream is done, it could return an empty MD. Client
 // side only.
 // It can be safely read only after stream has ended that is either read
@@ -499,36 +547,87 @@ func (s *Stream) write(m recvMsg) {
 	s.buf.put(m)
 }
 
-// Read reads all p bytes from the wire for this stream.
-func (s *Stream) Read(p []byte) (n int, err error) {
+func (s *Stream) ReadHeader(header []byte) (err error) {
 	// Don't request a read if there was an error earlier
-	if er := s.trReader.(*transportReader).er; er != nil {
-		return 0, er
+	if er := s.trReader.er; er != nil {
+		return er
 	}
-	s.requestRead(len(p))
-	return io.ReadFull(s.trReader, p)
+	s.requestRead(len(header))
+	for len(header) != 0 {
+		n, err := s.trReader.ReadHeader(header)
+		header = header[n:]
+		if len(header) == 0 {
+			err = nil
+		}
+		if err != nil {
+			if n > 0 && err == io.EOF {
+				err = io.ErrUnexpectedEOF
+			}
+			return err
+		}
+	}
+	return nil
 }
 
-// tranportReader reads all the data available for this Stream from the transport and
+// Read reads n bytes from the wire for this stream.
+func (s *Stream) Read(n int) (data mem.BufferSlice, err error) {
+	// Don't request a read if there was an error earlier
+	if er := s.trReader.er; er != nil {
+		return nil, er
+	}
+	s.requestRead(n)
+	for n != 0 {
+		buf, err := s.trReader.Read(n)
+		var bufLen int
+		if buf != nil {
+			bufLen = buf.Len()
+		}
+		n -= bufLen
+		if n == 0 {
+			err = nil
+		}
+		if err != nil {
+			if bufLen > 0 && err == io.EOF {
+				err = io.ErrUnexpectedEOF
+			}
+			data.Free()
+			return nil, err
+		}
+		data = append(data, buf)
+	}
+	return data, nil
+}
+
+// transportReader reads all the data available for this Stream from the transport and
 // passes them into the decoder, which converts them into a gRPC message stream.
 // The error is io.EOF when the stream is done or another non-nil error if
 // the stream broke.
 type transportReader struct {
-	reader io.Reader
+	reader *recvBufferReader
 	// The handler to control the window update procedure for both this
 	// particular stream and the associated transport.
 	windowHandler func(int)
 	er            error
 }
 
-func (t *transportReader) Read(p []byte) (n int, err error) {
-	n, err = t.reader.Read(p)
+func (t *transportReader) ReadHeader(header []byte) (int, error) {
+	n, err := t.reader.ReadHeader(header)
 	if err != nil {
 		t.er = err
-		return
+		return 0, err
 	}
-	t.windowHandler(n)
-	return
+	t.windowHandler(len(header))
+	return n, nil
+}
+
+func (t *transportReader) Read(n int) (mem.Buffer, error) {
+	buf, err := t.reader.Read(n)
+	if err != nil {
+		t.er = err
+		return buf, err
+	}
+	t.windowHandler(buf.Len())
+	return buf, nil
 }
 
 // BytesReceived indicates whether any bytes have been received on this stream.
@@ -574,6 +673,7 @@ type ServerConfig struct {
 	ChannelzParent        *channelz.Server
 	MaxHeaderListSize     *uint32
 	HeaderTableSize       *uint32
+	BufferPool            mem.BufferPool
 }
 
 // ConnectOptions covers all relevant options for communicating with the server.
@@ -612,6 +712,8 @@ type ConnectOptions struct {
 	MaxHeaderListSize *uint32
 	// UseProxy specifies if a proxy should be used.
 	UseProxy bool
+	// The mem.BufferPool to use when reading/writing to the wire.
+	BufferPool mem.BufferPool
 }
 
 // NewClientTransport establishes the transport with the required ConnectOptions
@@ -673,7 +775,7 @@ type ClientTransport interface {
 
 	// Write sends the data for the given stream. A nil stream indicates
 	// the write is to be performed on the transport as a whole.
-	Write(s *Stream, hdr []byte, data []byte, opts *Options) error
+	Write(s *Stream, hdr []byte, data mem.BufferSlice, opts *Options) error
 
 	// NewStream creates a Stream for an RPC.
 	NewStream(ctx context.Context, callHdr *CallHdr) (*Stream, error)
@@ -725,7 +827,7 @@ type ServerTransport interface {
 
 	// Write sends the data for the given stream.
 	// Write may not be called on all streams.
-	Write(s *Stream, hdr []byte, data []byte, opts *Options) error
+	Write(s *Stream, hdr []byte, data mem.BufferSlice, opts *Options) error
 
 	// WriteStatus sends the status of a stream to the client.  WriteStatus is
 	// the final call made on a stream and always occurs.
@@ -798,7 +900,7 @@ var (
 	// connection is draining. This could be caused by goaway or balancer
 	// removing the address.
 	errStreamDrain = status.Error(codes.Unavailable, "the connection is draining")
-	// errStreamDone is returned from write at the client side to indiacte application
+	// errStreamDone is returned from write at the client side to indicate application
 	// layer of an error.
 	errStreamDone = errors.New("the stream is done")
 	// StatusGoAway indicates that the server sent a GOAWAY that included this