diff --git a/vendor/google.golang.org/grpc/internal/transport/http2_client.go b/vendor/google.golang.org/grpc/internal/transport/http2_client.go
new file mode 100644
index 0000000..9bd8c27
--- /dev/null
+++ b/vendor/google.golang.org/grpc/internal/transport/http2_client.go
@@ -0,0 +1,1414 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package transport
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"math"
+	"net"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/hpack"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/internal/syscall"
+	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/peer"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+// http2Client implements the ClientTransport interface with HTTP2.
+type http2Client struct {
+	ctx        context.Context
+	cancel     context.CancelFunc
+	ctxDone    <-chan struct{} // Cache the ctx.Done() chan.
+	userAgent  string
+	md         interface{}
+	conn       net.Conn // underlying communication channel
+	loopy      *loopyWriter
+	remoteAddr net.Addr
+	localAddr  net.Addr
+	authInfo   credentials.AuthInfo // auth info about the connection
+
+	readerDone chan struct{} // sync point to enable testing.
+	writerDone chan struct{} // sync point to enable testing.
+	// goAway is closed to notify the upper layer (i.e., addrConn.transportMonitor)
+	// that the server sent GoAway on this transport.
+	goAway chan struct{}
+
+	framer *framer
+	// controlBuf delivers all the control related tasks (e.g., window
+	// updates, reset streams, and various settings) to the controller.
+	controlBuf *controlBuffer
+	fc         *trInFlow
+	// The scheme used: https if TLS is on, http otherwise.
+	scheme string
+
+	isSecure bool
+
+	perRPCCreds []credentials.PerRPCCredentials
+
+	// Boolean to keep track of reading activity on transport.
+	// 1 is true and 0 is false.
+	activity         uint32 // Accessed atomically.
+	kp               keepalive.ClientParameters
+	keepaliveEnabled bool
+
+	statsHandler stats.Handler
+
+	initialWindowSize int32
+
+	// configured by peer through SETTINGS_MAX_HEADER_LIST_SIZE
+	maxSendHeaderListSize *uint32
+
+	bdpEst *bdpEstimator
+	// onPrefaceReceipt is a callback that client transport calls upon
+	// receiving server preface to signal that a succefull HTTP2
+	// connection was established.
+	onPrefaceReceipt func()
+
+	maxConcurrentStreams  uint32
+	streamQuota           int64
+	streamsQuotaAvailable chan struct{}
+	waitingStreams        uint32
+	nextID                uint32
+
+	mu            sync.Mutex // guard the following variables
+	state         transportState
+	activeStreams map[uint32]*Stream
+	// prevGoAway ID records the Last-Stream-ID in the previous GOAway frame.
+	prevGoAwayID uint32
+	// goAwayReason records the http2.ErrCode and debug data received with the
+	// GoAway frame.
+	goAwayReason GoAwayReason
+	// A condition variable used to signal when the keepalive goroutine should
+	// go dormant. The condition for dormancy is based on the number of active
+	// streams and the `PermitWithoutStream` keepalive client parameter. And
+	// since the number of active streams is guarded by the above mutex, we use
+	// the same for this condition variable as well.
+	kpDormancyCond *sync.Cond
+	// A boolean to track whether the keepalive goroutine is dormant or not.
+	// This is checked before attempting to signal the above condition
+	// variable.
+	kpDormant bool
+
+	// Fields below are for channelz metric collection.
+	channelzID int64 // channelz unique identification number
+	czData     *channelzData
+
+	onGoAway func(GoAwayReason)
+	onClose  func()
+
+	bufferPool *bufferPool
+}
+
+func dial(ctx context.Context, fn func(context.Context, string) (net.Conn, error), addr string) (net.Conn, error) {
+	if fn != nil {
+		return fn(ctx, addr)
+	}
+	return (&net.Dialer{}).DialContext(ctx, "tcp", addr)
+}
+
+func isTemporary(err error) bool {
+	switch err := err.(type) {
+	case interface {
+		Temporary() bool
+	}:
+		return err.Temporary()
+	case interface {
+		Timeout() bool
+	}:
+		// Timeouts may be resolved upon retry, and are thus treated as
+		// temporary.
+		return err.Timeout()
+	}
+	return true
+}
+
+// newHTTP2Client constructs a connected ClientTransport to addr based on HTTP2
+// and starts to receive messages on it. Non-nil error returns if construction
+// fails.
+func newHTTP2Client(connectCtx, ctx context.Context, addr TargetInfo, opts ConnectOptions, onPrefaceReceipt func(), onGoAway func(GoAwayReason), onClose func()) (_ *http2Client, err error) {
+	scheme := "http"
+	ctx, cancel := context.WithCancel(ctx)
+	defer func() {
+		if err != nil {
+			cancel()
+		}
+	}()
+
+	conn, err := dial(connectCtx, opts.Dialer, addr.Addr)
+	if err != nil {
+		if opts.FailOnNonTempDialError {
+			return nil, connectionErrorf(isTemporary(err), err, "transport: error while dialing: %v", err)
+		}
+		return nil, connectionErrorf(true, err, "transport: Error while dialing %v", err)
+	}
+	// Any further errors will close the underlying connection
+	defer func(conn net.Conn) {
+		if err != nil {
+			conn.Close()
+		}
+	}(conn)
+	kp := opts.KeepaliveParams
+	// Validate keepalive parameters.
+	if kp.Time == 0 {
+		kp.Time = defaultClientKeepaliveTime
+	}
+	if kp.Timeout == 0 {
+		kp.Timeout = defaultClientKeepaliveTimeout
+	}
+	keepaliveEnabled := false
+	if kp.Time != infinity {
+		if err = syscall.SetTCPUserTimeout(conn, kp.Timeout); err != nil {
+			return nil, connectionErrorf(false, err, "transport: failed to set TCP_USER_TIMEOUT: %v", err)
+		}
+		keepaliveEnabled = true
+	}
+	var (
+		isSecure bool
+		authInfo credentials.AuthInfo
+	)
+	transportCreds := opts.TransportCredentials
+	perRPCCreds := opts.PerRPCCredentials
+
+	if b := opts.CredsBundle; b != nil {
+		if t := b.TransportCredentials(); t != nil {
+			transportCreds = t
+		}
+		if t := b.PerRPCCredentials(); t != nil {
+			perRPCCreds = append(perRPCCreds, t)
+		}
+	}
+	if transportCreds != nil {
+		scheme = "https"
+		conn, authInfo, err = transportCreds.ClientHandshake(connectCtx, addr.Authority, conn)
+		if err != nil {
+			return nil, connectionErrorf(isTemporary(err), err, "transport: authentication handshake failed: %v", err)
+		}
+		isSecure = true
+	}
+	dynamicWindow := true
+	icwz := int32(initialWindowSize)
+	if opts.InitialConnWindowSize >= defaultWindowSize {
+		icwz = opts.InitialConnWindowSize
+		dynamicWindow = false
+	}
+	writeBufSize := opts.WriteBufferSize
+	readBufSize := opts.ReadBufferSize
+	maxHeaderListSize := defaultClientMaxHeaderListSize
+	if opts.MaxHeaderListSize != nil {
+		maxHeaderListSize = *opts.MaxHeaderListSize
+	}
+	t := &http2Client{
+		ctx:                   ctx,
+		ctxDone:               ctx.Done(), // Cache Done chan.
+		cancel:                cancel,
+		userAgent:             opts.UserAgent,
+		md:                    addr.Metadata,
+		conn:                  conn,
+		remoteAddr:            conn.RemoteAddr(),
+		localAddr:             conn.LocalAddr(),
+		authInfo:              authInfo,
+		readerDone:            make(chan struct{}),
+		writerDone:            make(chan struct{}),
+		goAway:                make(chan struct{}),
+		framer:                newFramer(conn, writeBufSize, readBufSize, maxHeaderListSize),
+		fc:                    &trInFlow{limit: uint32(icwz)},
+		scheme:                scheme,
+		activeStreams:         make(map[uint32]*Stream),
+		isSecure:              isSecure,
+		perRPCCreds:           perRPCCreds,
+		kp:                    kp,
+		statsHandler:          opts.StatsHandler,
+		initialWindowSize:     initialWindowSize,
+		onPrefaceReceipt:      onPrefaceReceipt,
+		nextID:                1,
+		maxConcurrentStreams:  defaultMaxStreamsClient,
+		streamQuota:           defaultMaxStreamsClient,
+		streamsQuotaAvailable: make(chan struct{}, 1),
+		czData:                new(channelzData),
+		onGoAway:              onGoAway,
+		onClose:               onClose,
+		keepaliveEnabled:      keepaliveEnabled,
+		bufferPool:            newBufferPool(),
+	}
+	t.controlBuf = newControlBuffer(t.ctxDone)
+	if opts.InitialWindowSize >= defaultWindowSize {
+		t.initialWindowSize = opts.InitialWindowSize
+		dynamicWindow = false
+	}
+	if dynamicWindow {
+		t.bdpEst = &bdpEstimator{
+			bdp:               initialWindowSize,
+			updateFlowControl: t.updateFlowControl,
+		}
+	}
+	if t.statsHandler != nil {
+		t.ctx = t.statsHandler.TagConn(t.ctx, &stats.ConnTagInfo{
+			RemoteAddr: t.remoteAddr,
+			LocalAddr:  t.localAddr,
+		})
+		connBegin := &stats.ConnBegin{
+			Client: true,
+		}
+		t.statsHandler.HandleConn(t.ctx, connBegin)
+	}
+	if channelz.IsOn() {
+		t.channelzID = channelz.RegisterNormalSocket(t, opts.ChannelzParentID, fmt.Sprintf("%s -> %s", t.localAddr, t.remoteAddr))
+	}
+	if t.keepaliveEnabled {
+		t.kpDormancyCond = sync.NewCond(&t.mu)
+		go t.keepalive()
+	}
+	// Start the reader goroutine for incoming message. Each transport has
+	// a dedicated goroutine which reads HTTP2 frame from network. Then it
+	// dispatches the frame to the corresponding stream entity.
+	go t.reader()
+
+	// Send connection preface to server.
+	n, err := t.conn.Write(clientPreface)
+	if err != nil {
+		t.Close()
+		return nil, connectionErrorf(true, err, "transport: failed to write client preface: %v", err)
+	}
+	if n != len(clientPreface) {
+		t.Close()
+		return nil, connectionErrorf(true, err, "transport: preface mismatch, wrote %d bytes; want %d", n, len(clientPreface))
+	}
+	var ss []http2.Setting
+
+	if t.initialWindowSize != defaultWindowSize {
+		ss = append(ss, http2.Setting{
+			ID:  http2.SettingInitialWindowSize,
+			Val: uint32(t.initialWindowSize),
+		})
+	}
+	if opts.MaxHeaderListSize != nil {
+		ss = append(ss, http2.Setting{
+			ID:  http2.SettingMaxHeaderListSize,
+			Val: *opts.MaxHeaderListSize,
+		})
+	}
+	err = t.framer.fr.WriteSettings(ss...)
+	if err != nil {
+		t.Close()
+		return nil, connectionErrorf(true, err, "transport: failed to write initial settings frame: %v", err)
+	}
+	// Adjust the connection flow control window if needed.
+	if delta := uint32(icwz - defaultWindowSize); delta > 0 {
+		if err := t.framer.fr.WriteWindowUpdate(0, delta); err != nil {
+			t.Close()
+			return nil, connectionErrorf(true, err, "transport: failed to write window update: %v", err)
+		}
+	}
+
+	if err := t.framer.writer.Flush(); err != nil {
+		return nil, err
+	}
+	go func() {
+		t.loopy = newLoopyWriter(clientSide, t.framer, t.controlBuf, t.bdpEst)
+		err := t.loopy.run()
+		if err != nil {
+			errorf("transport: loopyWriter.run returning. Err: %v", err)
+		}
+		// If it's a connection error, let reader goroutine handle it
+		// since there might be data in the buffers.
+		if _, ok := err.(net.Error); !ok {
+			t.conn.Close()
+		}
+		close(t.writerDone)
+	}()
+	return t, nil
+}
+
+func (t *http2Client) newStream(ctx context.Context, callHdr *CallHdr) *Stream {
+	// TODO(zhaoq): Handle uint32 overflow of Stream.id.
+	s := &Stream{
+		done:           make(chan struct{}),
+		method:         callHdr.Method,
+		sendCompress:   callHdr.SendCompress,
+		buf:            newRecvBuffer(),
+		headerChan:     make(chan struct{}),
+		contentSubtype: callHdr.ContentSubtype,
+	}
+	s.wq = newWriteQuota(defaultWriteQuota, s.done)
+	s.requestRead = func(n int) {
+		t.adjustWindow(s, uint32(n))
+	}
+	// The client side stream context should have exactly the same life cycle with the user provided context.
+	// That means, s.ctx should be read-only. And s.ctx is done iff ctx is done.
+	// So we use the original context here instead of creating a copy.
+	s.ctx = ctx
+	s.trReader = &transportReader{
+		reader: &recvBufferReader{
+			ctx:     s.ctx,
+			ctxDone: s.ctx.Done(),
+			recv:    s.buf,
+			closeStream: func(err error) {
+				t.CloseStream(s, err)
+			},
+			freeBuffer: t.bufferPool.put,
+		},
+		windowHandler: func(n int) {
+			t.updateWindow(s, uint32(n))
+		},
+	}
+	return s
+}
+
+func (t *http2Client) getPeer() *peer.Peer {
+	pr := &peer.Peer{
+		Addr: t.remoteAddr,
+	}
+	// Attach Auth info if there is any.
+	if t.authInfo != nil {
+		pr.AuthInfo = t.authInfo
+	}
+	return pr
+}
+
+func (t *http2Client) createHeaderFields(ctx context.Context, callHdr *CallHdr) ([]hpack.HeaderField, error) {
+	aud := t.createAudience(callHdr)
+	authData, err := t.getTrAuthData(ctx, aud)
+	if err != nil {
+		return nil, err
+	}
+	callAuthData, err := t.getCallAuthData(ctx, aud, callHdr)
+	if err != nil {
+		return nil, err
+	}
+	// TODO(mmukhi): Benchmark if the performance gets better if count the metadata and other header fields
+	// first and create a slice of that exact size.
+	// Make the slice of certain predictable size to reduce allocations made by append.
+	hfLen := 7 // :method, :scheme, :path, :authority, content-type, user-agent, te
+	hfLen += len(authData) + len(callAuthData)
+	headerFields := make([]hpack.HeaderField, 0, hfLen)
+	headerFields = append(headerFields, hpack.HeaderField{Name: ":method", Value: "POST"})
+	headerFields = append(headerFields, hpack.HeaderField{Name: ":scheme", Value: t.scheme})
+	headerFields = append(headerFields, hpack.HeaderField{Name: ":path", Value: callHdr.Method})
+	headerFields = append(headerFields, hpack.HeaderField{Name: ":authority", Value: callHdr.Host})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "content-type", Value: contentType(callHdr.ContentSubtype)})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "user-agent", Value: t.userAgent})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "te", Value: "trailers"})
+	if callHdr.PreviousAttempts > 0 {
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-previous-rpc-attempts", Value: strconv.Itoa(callHdr.PreviousAttempts)})
+	}
+
+	if callHdr.SendCompress != "" {
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-encoding", Value: callHdr.SendCompress})
+	}
+	if dl, ok := ctx.Deadline(); ok {
+		// Send out timeout regardless its value. The server can detect timeout context by itself.
+		// TODO(mmukhi): Perhaps this field should be updated when actually writing out to the wire.
+		timeout := time.Until(dl)
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-timeout", Value: encodeTimeout(timeout)})
+	}
+	for k, v := range authData {
+		headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+	}
+	for k, v := range callAuthData {
+		headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+	}
+	if b := stats.OutgoingTags(ctx); b != nil {
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-tags-bin", Value: encodeBinHeader(b)})
+	}
+	if b := stats.OutgoingTrace(ctx); b != nil {
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-trace-bin", Value: encodeBinHeader(b)})
+	}
+
+	if md, added, ok := metadata.FromOutgoingContextRaw(ctx); ok {
+		var k string
+		for k, vv := range md {
+			// HTTP doesn't allow you to set pseudoheaders after non pseudoheaders were set.
+			if isReservedHeader(k) {
+				continue
+			}
+			for _, v := range vv {
+				headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+			}
+		}
+		for _, vv := range added {
+			for i, v := range vv {
+				if i%2 == 0 {
+					k = v
+					continue
+				}
+				// HTTP doesn't allow you to set pseudoheaders after non pseudoheaders were set.
+				if isReservedHeader(k) {
+					continue
+				}
+				headerFields = append(headerFields, hpack.HeaderField{Name: strings.ToLower(k), Value: encodeMetadataHeader(k, v)})
+			}
+		}
+	}
+	if md, ok := t.md.(*metadata.MD); ok {
+		for k, vv := range *md {
+			if isReservedHeader(k) {
+				continue
+			}
+			for _, v := range vv {
+				headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
+			}
+		}
+	}
+	return headerFields, nil
+}
+
+func (t *http2Client) createAudience(callHdr *CallHdr) string {
+	// Create an audience string only if needed.
+	if len(t.perRPCCreds) == 0 && callHdr.Creds == nil {
+		return ""
+	}
+	// Construct URI required to get auth request metadata.
+	// Omit port if it is the default one.
+	host := strings.TrimSuffix(callHdr.Host, ":443")
+	pos := strings.LastIndex(callHdr.Method, "/")
+	if pos == -1 {
+		pos = len(callHdr.Method)
+	}
+	return "https://" + host + callHdr.Method[:pos]
+}
+
+func (t *http2Client) getTrAuthData(ctx context.Context, audience string) (map[string]string, error) {
+	if len(t.perRPCCreds) == 0 {
+		return nil, nil
+	}
+	authData := map[string]string{}
+	for _, c := range t.perRPCCreds {
+		data, err := c.GetRequestMetadata(ctx, audience)
+		if err != nil {
+			if _, ok := status.FromError(err); ok {
+				return nil, err
+			}
+
+			return nil, status.Errorf(codes.Unauthenticated, "transport: %v", err)
+		}
+		for k, v := range data {
+			// Capital header names are illegal in HTTP/2.
+			k = strings.ToLower(k)
+			authData[k] = v
+		}
+	}
+	return authData, nil
+}
+
+func (t *http2Client) getCallAuthData(ctx context.Context, audience string, callHdr *CallHdr) (map[string]string, error) {
+	var callAuthData map[string]string
+	// Check if credentials.PerRPCCredentials were provided via call options.
+	// Note: if these credentials are provided both via dial options and call
+	// options, then both sets of credentials will be applied.
+	if callCreds := callHdr.Creds; callCreds != nil {
+		if !t.isSecure && callCreds.RequireTransportSecurity() {
+			return nil, status.Error(codes.Unauthenticated, "transport: cannot send secure credentials on an insecure connection")
+		}
+		data, err := callCreds.GetRequestMetadata(ctx, audience)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "transport: %v", err)
+		}
+		callAuthData = make(map[string]string, len(data))
+		for k, v := range data {
+			// Capital header names are illegal in HTTP/2
+			k = strings.ToLower(k)
+			callAuthData[k] = v
+		}
+	}
+	return callAuthData, nil
+}
+
+// NewStream creates a stream and registers it into the transport as "active"
+// streams.
+func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Stream, err error) {
+	ctx = peer.NewContext(ctx, t.getPeer())
+	headerFields, err := t.createHeaderFields(ctx, callHdr)
+	if err != nil {
+		return nil, err
+	}
+	s := t.newStream(ctx, callHdr)
+	cleanup := func(err error) {
+		if s.swapState(streamDone) == streamDone {
+			// If it was already done, return.
+			return
+		}
+		// The stream was unprocessed by the server.
+		atomic.StoreUint32(&s.unprocessed, 1)
+		s.write(recvMsg{err: err})
+		close(s.done)
+		// If headerChan isn't closed, then close it.
+		if atomic.CompareAndSwapUint32(&s.headerChanClosed, 0, 1) {
+			close(s.headerChan)
+		}
+	}
+	hdr := &headerFrame{
+		hf:        headerFields,
+		endStream: false,
+		initStream: func(id uint32) error {
+			t.mu.Lock()
+			if state := t.state; state != reachable {
+				t.mu.Unlock()
+				// Do a quick cleanup.
+				err := error(errStreamDrain)
+				if state == closing {
+					err = ErrConnClosing
+				}
+				cleanup(err)
+				return err
+			}
+			t.activeStreams[id] = s
+			if channelz.IsOn() {
+				atomic.AddInt64(&t.czData.streamsStarted, 1)
+				atomic.StoreInt64(&t.czData.lastStreamCreatedTime, time.Now().UnixNano())
+			}
+			// If the keepalive goroutine has gone dormant, wake it up.
+			if t.kpDormant {
+				t.kpDormancyCond.Signal()
+			}
+			t.mu.Unlock()
+			return nil
+		},
+		onOrphaned: cleanup,
+		wq:         s.wq,
+	}
+	firstTry := true
+	var ch chan struct{}
+	checkForStreamQuota := func(it interface{}) bool {
+		if t.streamQuota <= 0 { // Can go negative if server decreases it.
+			if firstTry {
+				t.waitingStreams++
+			}
+			ch = t.streamsQuotaAvailable
+			return false
+		}
+		if !firstTry {
+			t.waitingStreams--
+		}
+		t.streamQuota--
+		h := it.(*headerFrame)
+		h.streamID = t.nextID
+		t.nextID += 2
+		s.id = h.streamID
+		s.fc = &inFlow{limit: uint32(t.initialWindowSize)}
+		if t.streamQuota > 0 && t.waitingStreams > 0 {
+			select {
+			case t.streamsQuotaAvailable <- struct{}{}:
+			default:
+			}
+		}
+		return true
+	}
+	var hdrListSizeErr error
+	checkForHeaderListSize := func(it interface{}) bool {
+		if t.maxSendHeaderListSize == nil {
+			return true
+		}
+		hdrFrame := it.(*headerFrame)
+		var sz int64
+		for _, f := range hdrFrame.hf {
+			if sz += int64(f.Size()); sz > int64(*t.maxSendHeaderListSize) {
+				hdrListSizeErr = status.Errorf(codes.Internal, "header list size to send violates the maximum size (%d bytes) set by server", *t.maxSendHeaderListSize)
+				return false
+			}
+		}
+		return true
+	}
+	for {
+		success, err := t.controlBuf.executeAndPut(func(it interface{}) bool {
+			if !checkForStreamQuota(it) {
+				return false
+			}
+			if !checkForHeaderListSize(it) {
+				return false
+			}
+			return true
+		}, hdr)
+		if err != nil {
+			return nil, err
+		}
+		if success {
+			break
+		}
+		if hdrListSizeErr != nil {
+			return nil, hdrListSizeErr
+		}
+		firstTry = false
+		select {
+		case <-ch:
+		case <-s.ctx.Done():
+			return nil, ContextErr(s.ctx.Err())
+		case <-t.goAway:
+			return nil, errStreamDrain
+		case <-t.ctx.Done():
+			return nil, ErrConnClosing
+		}
+	}
+	if t.statsHandler != nil {
+		outHeader := &stats.OutHeader{
+			Client:      true,
+			FullMethod:  callHdr.Method,
+			RemoteAddr:  t.remoteAddr,
+			LocalAddr:   t.localAddr,
+			Compression: callHdr.SendCompress,
+		}
+		t.statsHandler.HandleRPC(s.ctx, outHeader)
+	}
+	return s, nil
+}
+
+// CloseStream clears the footprint of a stream when the stream is not needed any more.
+// This must not be executed in reader's goroutine.
+func (t *http2Client) CloseStream(s *Stream, err error) {
+	var (
+		rst     bool
+		rstCode http2.ErrCode
+	)
+	if err != nil {
+		rst = true
+		rstCode = http2.ErrCodeCancel
+	}
+	t.closeStream(s, err, rst, rstCode, status.Convert(err), nil, false)
+}
+
+func (t *http2Client) closeStream(s *Stream, err error, rst bool, rstCode http2.ErrCode, st *status.Status, mdata map[string][]string, eosReceived bool) {
+	// Set stream status to done.
+	if s.swapState(streamDone) == streamDone {
+		// If it was already done, return.  If multiple closeStream calls
+		// happen simultaneously, wait for the first to finish.
+		<-s.done
+		return
+	}
+	// status and trailers can be updated here without any synchronization because the stream goroutine will
+	// only read it after it sees an io.EOF error from read or write and we'll write those errors
+	// only after updating this.
+	s.status = st
+	if len(mdata) > 0 {
+		s.trailer = mdata
+	}
+	if err != nil {
+		// This will unblock reads eventually.
+		s.write(recvMsg{err: err})
+	}
+	// If headerChan isn't closed, then close it.
+	if atomic.CompareAndSwapUint32(&s.headerChanClosed, 0, 1) {
+		s.noHeaders = true
+		close(s.headerChan)
+	}
+	cleanup := &cleanupStream{
+		streamID: s.id,
+		onWrite: func() {
+			t.mu.Lock()
+			if t.activeStreams != nil {
+				delete(t.activeStreams, s.id)
+			}
+			t.mu.Unlock()
+			if channelz.IsOn() {
+				if eosReceived {
+					atomic.AddInt64(&t.czData.streamsSucceeded, 1)
+				} else {
+					atomic.AddInt64(&t.czData.streamsFailed, 1)
+				}
+			}
+		},
+		rst:     rst,
+		rstCode: rstCode,
+	}
+	addBackStreamQuota := func(interface{}) bool {
+		t.streamQuota++
+		if t.streamQuota > 0 && t.waitingStreams > 0 {
+			select {
+			case t.streamsQuotaAvailable <- struct{}{}:
+			default:
+			}
+		}
+		return true
+	}
+	t.controlBuf.executeAndPut(addBackStreamQuota, cleanup)
+	// This will unblock write.
+	close(s.done)
+}
+
+// Close kicks off the shutdown process of the transport. This should be called
+// only once on a transport. Once it is called, the transport should not be
+// accessed any more.
+//
+// This method blocks until the addrConn that initiated this transport is
+// re-connected. This happens because t.onClose() begins reconnect logic at the
+// addrConn level and blocks until the addrConn is successfully connected.
+func (t *http2Client) Close() error {
+	t.mu.Lock()
+	// Make sure we only Close once.
+	if t.state == closing {
+		t.mu.Unlock()
+		return nil
+	}
+	// Call t.onClose before setting the state to closing to prevent the client
+	// from attempting to create new streams ASAP.
+	t.onClose()
+	t.state = closing
+	streams := t.activeStreams
+	t.activeStreams = nil
+	if t.kpDormant {
+		// If the keepalive goroutine is blocked on this condition variable, we
+		// should unblock it so that the goroutine eventually exits.
+		t.kpDormancyCond.Signal()
+	}
+	t.mu.Unlock()
+	t.controlBuf.finish()
+	t.cancel()
+	err := t.conn.Close()
+	if channelz.IsOn() {
+		channelz.RemoveEntry(t.channelzID)
+	}
+	// Notify all active streams.
+	for _, s := range streams {
+		t.closeStream(s, ErrConnClosing, false, http2.ErrCodeNo, status.New(codes.Unavailable, ErrConnClosing.Desc), nil, false)
+	}
+	if t.statsHandler != nil {
+		connEnd := &stats.ConnEnd{
+			Client: true,
+		}
+		t.statsHandler.HandleConn(t.ctx, connEnd)
+	}
+	return err
+}
+
+// GracefulClose sets the state to draining, which prevents new streams from
+// being created and causes the transport to be closed when the last active
+// stream is closed.  If there are no active streams, the transport is closed
+// immediately.  This does nothing if the transport is already draining or
+// closing.
+func (t *http2Client) GracefulClose() {
+	t.mu.Lock()
+	// Make sure we move to draining only from active.
+	if t.state == draining || t.state == closing {
+		t.mu.Unlock()
+		return
+	}
+	t.state = draining
+	active := len(t.activeStreams)
+	t.mu.Unlock()
+	if active == 0 {
+		t.Close()
+		return
+	}
+	t.controlBuf.put(&incomingGoAway{})
+}
+
+// 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 {
+	if opts.Last {
+		// If it's the last message, update stream state.
+		if !s.compareAndSwapState(streamActive, streamWriteDone) {
+			return errStreamDone
+		}
+	} else if s.getState() != streamActive {
+		return errStreamDone
+	}
+	df := &dataFrame{
+		streamID:  s.id,
+		endStream: opts.Last,
+	}
+	if hdr != nil || data != nil { // If it's not an empty data frame.
+		// Add some data to grpc message header so that we can equally
+		// distribute bytes across frames.
+		emptyLen := http2MaxFrameLen - len(hdr)
+		if emptyLen > len(data) {
+			emptyLen = len(data)
+		}
+		hdr = append(hdr, data[:emptyLen]...)
+		data = data[emptyLen:]
+		df.h, df.d = hdr, data
+		// TODO(mmukhi): The above logic in this if can be moved to loopyWriter's data handler.
+		if err := s.wq.get(int32(len(hdr) + len(data))); err != nil {
+			return err
+		}
+	}
+	return t.controlBuf.put(df)
+}
+
+func (t *http2Client) getStream(f http2.Frame) *Stream {
+	t.mu.Lock()
+	s := t.activeStreams[f.Header().StreamID]
+	t.mu.Unlock()
+	return s
+}
+
+// adjustWindow sends out extra window update over the initial window size
+// of stream if the application is requesting data larger in size than
+// the window.
+func (t *http2Client) adjustWindow(s *Stream, n uint32) {
+	if w := s.fc.maybeAdjust(n); w > 0 {
+		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id, increment: w})
+	}
+}
+
+// updateWindow adjusts the inbound quota for the stream.
+// Window updates will be sent out when the cumulative quota
+// exceeds the corresponding threshold.
+func (t *http2Client) updateWindow(s *Stream, n uint32) {
+	if w := s.fc.onRead(n); w > 0 {
+		t.controlBuf.put(&outgoingWindowUpdate{streamID: s.id, increment: w})
+	}
+}
+
+// updateFlowControl updates the incoming flow control windows
+// for the transport and the stream based on the current bdp
+// estimation.
+func (t *http2Client) updateFlowControl(n uint32) {
+	t.mu.Lock()
+	for _, s := range t.activeStreams {
+		s.fc.newLimit(n)
+	}
+	t.mu.Unlock()
+	updateIWS := func(interface{}) bool {
+		t.initialWindowSize = int32(n)
+		return true
+	}
+	t.controlBuf.executeAndPut(updateIWS, &outgoingWindowUpdate{streamID: 0, increment: t.fc.newLimit(n)})
+	t.controlBuf.put(&outgoingSettings{
+		ss: []http2.Setting{
+			{
+				ID:  http2.SettingInitialWindowSize,
+				Val: n,
+			},
+		},
+	})
+}
+
+func (t *http2Client) handleData(f *http2.DataFrame) {
+	size := f.Header().Length
+	var sendBDPPing bool
+	if t.bdpEst != nil {
+		sendBDPPing = t.bdpEst.add(size)
+	}
+	// Decouple connection's flow control from application's read.
+	// An update on connection's flow control should not depend on
+	// whether user application has read the data or not. Such a
+	// restriction is already imposed on the stream's flow control,
+	// and therefore the sender will be blocked anyways.
+	// Decoupling the connection flow control will prevent other
+	// active(fast) streams from starving in presence of slow or
+	// inactive streams.
+	//
+	if w := t.fc.onData(size); w > 0 {
+		t.controlBuf.put(&outgoingWindowUpdate{
+			streamID:  0,
+			increment: w,
+		})
+	}
+	if sendBDPPing {
+		// Avoid excessive ping detection (e.g. in an L7 proxy)
+		// by sending a window update prior to the BDP ping.
+
+		if w := t.fc.reset(); w > 0 {
+			t.controlBuf.put(&outgoingWindowUpdate{
+				streamID:  0,
+				increment: w,
+			})
+		}
+
+		t.controlBuf.put(bdpPing)
+	}
+	// Select the right stream to dispatch.
+	s := t.getStream(f)
+	if s == nil {
+		return
+	}
+	if size > 0 {
+		if err := s.fc.onData(size); err != nil {
+			t.closeStream(s, io.EOF, true, http2.ErrCodeFlowControl, status.New(codes.Internal, err.Error()), nil, false)
+			return
+		}
+		if f.Header().Flags.Has(http2.FlagDataPadded) {
+			if w := s.fc.onRead(size - uint32(len(f.Data()))); w > 0 {
+				t.controlBuf.put(&outgoingWindowUpdate{s.id, w})
+			}
+		}
+		// TODO(bradfitz, zhaoq): A copy is required here because there is no
+		// 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})
+		}
+	}
+	// The server has closed the stream without sending trailers.  Record that
+	// the read direction is closed, and set the status appropriately.
+	if f.FrameHeader.Flags.Has(http2.FlagDataEndStream) {
+		t.closeStream(s, io.EOF, false, http2.ErrCodeNo, status.New(codes.Internal, "server closed the stream without sending trailers"), nil, true)
+	}
+}
+
+func (t *http2Client) handleRSTStream(f *http2.RSTStreamFrame) {
+	s := t.getStream(f)
+	if s == nil {
+		return
+	}
+	if f.ErrCode == http2.ErrCodeRefusedStream {
+		// The stream was unprocessed by the server.
+		atomic.StoreUint32(&s.unprocessed, 1)
+	}
+	statusCode, ok := http2ErrConvTab[f.ErrCode]
+	if !ok {
+		warningf("transport: http2Client.handleRSTStream found no mapped gRPC status for the received http2 error %v", f.ErrCode)
+		statusCode = codes.Unknown
+	}
+	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.
+			statusCode = codes.DeadlineExceeded
+		}
+	}
+	t.closeStream(s, io.EOF, false, http2.ErrCodeNo, status.Newf(statusCode, "stream terminated by RST_STREAM with error code: %v", f.ErrCode), nil, false)
+}
+
+func (t *http2Client) handleSettings(f *http2.SettingsFrame, isFirst bool) {
+	if f.IsAck() {
+		return
+	}
+	var maxStreams *uint32
+	var ss []http2.Setting
+	var updateFuncs []func()
+	f.ForeachSetting(func(s http2.Setting) error {
+		switch s.ID {
+		case http2.SettingMaxConcurrentStreams:
+			maxStreams = new(uint32)
+			*maxStreams = s.Val
+		case http2.SettingMaxHeaderListSize:
+			updateFuncs = append(updateFuncs, func() {
+				t.maxSendHeaderListSize = new(uint32)
+				*t.maxSendHeaderListSize = s.Val
+			})
+		default:
+			ss = append(ss, s)
+		}
+		return nil
+	})
+	if isFirst && maxStreams == nil {
+		maxStreams = new(uint32)
+		*maxStreams = math.MaxUint32
+	}
+	sf := &incomingSettings{
+		ss: ss,
+	}
+	if maxStreams != nil {
+		updateStreamQuota := func() {
+			delta := int64(*maxStreams) - int64(t.maxConcurrentStreams)
+			t.maxConcurrentStreams = *maxStreams
+			t.streamQuota += delta
+			if delta > 0 && t.waitingStreams > 0 {
+				close(t.streamsQuotaAvailable) // wake all of them up.
+				t.streamsQuotaAvailable = make(chan struct{}, 1)
+			}
+		}
+		updateFuncs = append(updateFuncs, updateStreamQuota)
+	}
+	t.controlBuf.executeAndPut(func(interface{}) bool {
+		for _, f := range updateFuncs {
+			f()
+		}
+		return true
+	}, sf)
+}
+
+func (t *http2Client) handlePing(f *http2.PingFrame) {
+	if f.IsAck() {
+		// Maybe it's a BDP ping.
+		if t.bdpEst != nil {
+			t.bdpEst.calculate(f.Data)
+		}
+		return
+	}
+	pingAck := &ping{ack: true}
+	copy(pingAck.data[:], f.Data[:])
+	t.controlBuf.put(pingAck)
+}
+
+func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
+	t.mu.Lock()
+	if t.state == closing {
+		t.mu.Unlock()
+		return
+	}
+	if f.ErrCode == http2.ErrCodeEnhanceYourCalm {
+		infof("Client received GoAway with http2.ErrCodeEnhanceYourCalm.")
+	}
+	id := f.LastStreamID
+	if id > 0 && id%2 != 1 {
+		t.mu.Unlock()
+		t.Close()
+		return
+	}
+	// A client can receive multiple GoAways from the server (see
+	// https://github.com/grpc/grpc-go/issues/1387).  The idea is that the first
+	// GoAway will be sent with an ID of MaxInt32 and the second GoAway will be
+	// sent after an RTT delay with the ID of the last stream the server will
+	// process.
+	//
+	// Therefore, when we get the first GoAway we don't necessarily close any
+	// streams. While in case of second GoAway we close all streams created after
+	// the GoAwayId. This way streams that were in-flight while the GoAway from
+	// server was being sent don't get killed.
+	select {
+	case <-t.goAway: // t.goAway has been closed (i.e.,multiple GoAways).
+		// If there are multiple GoAways the first one should always have an ID greater than the following ones.
+		if id > t.prevGoAwayID {
+			t.mu.Unlock()
+			t.Close()
+			return
+		}
+	default:
+		t.setGoAwayReason(f)
+		close(t.goAway)
+		t.controlBuf.put(&incomingGoAway{})
+		// Notify the clientconn about the GOAWAY before we set the state to
+		// draining, to allow the client to stop attempting to create streams
+		// before disallowing new streams on this connection.
+		t.onGoAway(t.goAwayReason)
+		t.state = draining
+	}
+	// All streams with IDs greater than the GoAwayId
+	// and smaller than the previous GoAway ID should be killed.
+	upperLimit := t.prevGoAwayID
+	if upperLimit == 0 { // This is the first GoAway Frame.
+		upperLimit = math.MaxUint32 // Kill all streams after the GoAway ID.
+	}
+	for streamID, stream := range t.activeStreams {
+		if streamID > id && streamID <= upperLimit {
+			// The stream was unprocessed by the server.
+			atomic.StoreUint32(&stream.unprocessed, 1)
+			t.closeStream(stream, errStreamDrain, false, http2.ErrCodeNo, statusGoAway, nil, false)
+		}
+	}
+	t.prevGoAwayID = id
+	active := len(t.activeStreams)
+	t.mu.Unlock()
+	if active == 0 {
+		t.Close()
+	}
+}
+
+// setGoAwayReason sets the value of t.goAwayReason based
+// on the GoAway frame received.
+// It expects a lock on transport's mutext to be held by
+// the caller.
+func (t *http2Client) setGoAwayReason(f *http2.GoAwayFrame) {
+	t.goAwayReason = GoAwayNoReason
+	switch f.ErrCode {
+	case http2.ErrCodeEnhanceYourCalm:
+		if string(f.DebugData()) == "too_many_pings" {
+			t.goAwayReason = GoAwayTooManyPings
+		}
+	}
+}
+
+func (t *http2Client) GetGoAwayReason() GoAwayReason {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.goAwayReason
+}
+
+func (t *http2Client) handleWindowUpdate(f *http2.WindowUpdateFrame) {
+	t.controlBuf.put(&incomingWindowUpdate{
+		streamID:  f.Header().StreamID,
+		increment: f.Increment,
+	})
+}
+
+// operateHeaders takes action on the decoded headers.
+func (t *http2Client) operateHeaders(frame *http2.MetaHeadersFrame) {
+	s := t.getStream(frame)
+	if s == nil {
+		return
+	}
+	endStream := frame.StreamEnded()
+	atomic.StoreUint32(&s.bytesReceived, 1)
+	initialHeader := atomic.LoadUint32(&s.headerChanClosed) == 0
+
+	if !initialHeader && !endStream {
+		// As specified by gRPC over HTTP2, a HEADERS frame (and associated CONTINUATION frames) can only appear at the start or end of a stream. Therefore, second HEADERS frame must have EOS bit set.
+		st := status.New(codes.Internal, "a HEADERS frame cannot appear in the middle of a stream")
+		t.closeStream(s, st.Err(), true, http2.ErrCodeProtocol, st, nil, false)
+		return
+	}
+
+	state := &decodeState{}
+	// Initialize isGRPC value to be !initialHeader, since if a gRPC Response-Headers has already been received, then it means that the peer is speaking gRPC and we are in gRPC mode.
+	state.data.isGRPC = !initialHeader
+	if err := state.decodeHeader(frame); err != nil {
+		t.closeStream(s, err, true, http2.ErrCodeProtocol, status.Convert(err), nil, endStream)
+		return
+	}
+
+	isHeader := false
+	defer func() {
+		if t.statsHandler != nil {
+			if isHeader {
+				inHeader := &stats.InHeader{
+					Client:     true,
+					WireLength: int(frame.Header().Length),
+				}
+				t.statsHandler.HandleRPC(s.ctx, inHeader)
+			} else {
+				inTrailer := &stats.InTrailer{
+					Client:     true,
+					WireLength: int(frame.Header().Length),
+				}
+				t.statsHandler.HandleRPC(s.ctx, inTrailer)
+			}
+		}
+	}()
+
+	// If headerChan hasn't been closed yet
+	if atomic.CompareAndSwapUint32(&s.headerChanClosed, 0, 1) {
+		if !endStream {
+			// HEADERS frame block carries a Response-Headers.
+			isHeader = true
+			// These values can be set without any synchronization because
+			// stream goroutine will read it only after seeing a closed
+			// headerChan which we'll close after setting this.
+			s.recvCompress = state.data.encoding
+			if len(state.data.mdata) > 0 {
+				s.header = state.data.mdata
+			}
+		} else {
+			// HEADERS frame block carries a Trailers-Only.
+			s.noHeaders = true
+		}
+		close(s.headerChan)
+	}
+
+	if !endStream {
+		return
+	}
+
+	// if client received END_STREAM from server while stream was still active, send RST_STREAM
+	rst := s.getState() == streamActive
+	t.closeStream(s, io.EOF, rst, http2.ErrCodeNo, state.status(), state.data.mdata, true)
+}
+
+// reader runs as a separate goroutine in charge of reading data from network
+// connection.
+//
+// TODO(zhaoq): currently one reader per transport. Investigate whether this is
+// optimal.
+// TODO(zhaoq): Check the validity of the incoming frame sequence.
+func (t *http2Client) reader() {
+	defer close(t.readerDone)
+	// Check the validity of server preface.
+	frame, err := t.framer.fr.ReadFrame()
+	if err != nil {
+		t.Close() // this kicks off resetTransport, so must be last before return
+		return
+	}
+	t.conn.SetReadDeadline(time.Time{}) // reset deadline once we get the settings frame (we didn't time out, yay!)
+	if t.keepaliveEnabled {
+		atomic.CompareAndSwapUint32(&t.activity, 0, 1)
+	}
+	sf, ok := frame.(*http2.SettingsFrame)
+	if !ok {
+		t.Close() // this kicks off resetTransport, so must be last before return
+		return
+	}
+	t.onPrefaceReceipt()
+	t.handleSettings(sf, true)
+
+	// loop to keep reading incoming messages on this transport.
+	for {
+		t.controlBuf.throttle()
+		frame, err := t.framer.fr.ReadFrame()
+		if t.keepaliveEnabled {
+			atomic.CompareAndSwapUint32(&t.activity, 0, 1)
+		}
+		if err != nil {
+			// Abort an active stream if the http2.Framer returns a
+			// http2.StreamError. This can happen only if the server's response
+			// is malformed http2.
+			if se, ok := err.(http2.StreamError); ok {
+				t.mu.Lock()
+				s := t.activeStreams[se.StreamID]
+				t.mu.Unlock()
+				if s != nil {
+					// use error detail to provide better err message
+					code := http2ErrConvTab[se.Code]
+					msg := t.framer.fr.ErrorDetail().Error()
+					t.closeStream(s, status.Error(code, msg), true, http2.ErrCodeProtocol, status.New(code, msg), nil, false)
+				}
+				continue
+			} else {
+				// Transport error.
+				t.Close()
+				return
+			}
+		}
+		switch frame := frame.(type) {
+		case *http2.MetaHeadersFrame:
+			t.operateHeaders(frame)
+		case *http2.DataFrame:
+			t.handleData(frame)
+		case *http2.RSTStreamFrame:
+			t.handleRSTStream(frame)
+		case *http2.SettingsFrame:
+			t.handleSettings(frame, false)
+		case *http2.PingFrame:
+			t.handlePing(frame)
+		case *http2.GoAwayFrame:
+			t.handleGoAway(frame)
+		case *http2.WindowUpdateFrame:
+			t.handleWindowUpdate(frame)
+		default:
+			errorf("transport: http2Client.reader got unhandled frame type %v.", frame)
+		}
+	}
+}
+
+// keepalive running in a separate goroutune makes sure the connection is alive by sending pings.
+func (t *http2Client) keepalive() {
+	p := &ping{data: [8]byte{}}
+	timer := time.NewTimer(t.kp.Time)
+	for {
+		select {
+		case <-timer.C:
+			if atomic.CompareAndSwapUint32(&t.activity, 1, 0) {
+				timer.Reset(t.kp.Time)
+				continue
+			}
+			t.mu.Lock()
+			if t.state == closing {
+				// If the transport is closing, we should exit from the
+				// keepalive goroutine here. If not, we could have a race
+				// between the call to Signal() from Close() and the call to
+				// Wait() here, whereby the keepalive goroutine ends up
+				// blocking on the condition variable which will never be
+				// signalled again.
+				t.mu.Unlock()
+				return
+			}
+			if len(t.activeStreams) < 1 && !t.kp.PermitWithoutStream {
+				t.kpDormant = true
+				t.kpDormancyCond.Wait()
+			}
+			t.kpDormant = false
+			t.mu.Unlock()
+
+			if channelz.IsOn() {
+				atomic.AddInt64(&t.czData.kpCount, 1)
+			}
+			// We get here either because we were dormant and a new stream was
+			// created which unblocked the Wait() call, or because the
+			// keepalive timer expired. In both cases, we need to send a ping.
+			t.controlBuf.put(p)
+
+			timer.Reset(t.kp.Timeout)
+			select {
+			case <-timer.C:
+				if atomic.CompareAndSwapUint32(&t.activity, 1, 0) {
+					timer.Reset(t.kp.Time)
+					continue
+				}
+				infof("transport: closing client transport due to idleness.")
+				t.Close()
+				return
+			case <-t.ctx.Done():
+				if !timer.Stop() {
+					<-timer.C
+				}
+				return
+			}
+		case <-t.ctx.Done():
+			if !timer.Stop() {
+				<-timer.C
+			}
+			return
+		}
+	}
+}
+
+func (t *http2Client) Error() <-chan struct{} {
+	return t.ctx.Done()
+}
+
+func (t *http2Client) GoAway() <-chan struct{} {
+	return t.goAway
+}
+
+func (t *http2Client) ChannelzMetric() *channelz.SocketInternalMetric {
+	s := channelz.SocketInternalMetric{
+		StreamsStarted:                  atomic.LoadInt64(&t.czData.streamsStarted),
+		StreamsSucceeded:                atomic.LoadInt64(&t.czData.streamsSucceeded),
+		StreamsFailed:                   atomic.LoadInt64(&t.czData.streamsFailed),
+		MessagesSent:                    atomic.LoadInt64(&t.czData.msgSent),
+		MessagesReceived:                atomic.LoadInt64(&t.czData.msgRecv),
+		KeepAlivesSent:                  atomic.LoadInt64(&t.czData.kpCount),
+		LastLocalStreamCreatedTimestamp: time.Unix(0, atomic.LoadInt64(&t.czData.lastStreamCreatedTime)),
+		LastMessageSentTimestamp:        time.Unix(0, atomic.LoadInt64(&t.czData.lastMsgSentTime)),
+		LastMessageReceivedTimestamp:    time.Unix(0, atomic.LoadInt64(&t.czData.lastMsgRecvTime)),
+		LocalFlowControlWindow:          int64(t.fc.getSize()),
+		SocketOptions:                   channelz.GetSocketOption(t.conn),
+		LocalAddr:                       t.localAddr,
+		RemoteAddr:                      t.remoteAddr,
+		// RemoteName :
+	}
+	if au, ok := t.authInfo.(credentials.ChannelzSecurityInfo); ok {
+		s.Security = au.GetSecurityValue()
+	}
+	s.RemoteFlowControlWindow = t.getOutFlowWindow()
+	return &s
+}
+
+func (t *http2Client) RemoteAddr() net.Addr { return t.remoteAddr }
+
+func (t *http2Client) IncrMsgSent() {
+	atomic.AddInt64(&t.czData.msgSent, 1)
+	atomic.StoreInt64(&t.czData.lastMsgSentTime, time.Now().UnixNano())
+}
+
+func (t *http2Client) IncrMsgRecv() {
+	atomic.AddInt64(&t.czData.msgRecv, 1)
+	atomic.StoreInt64(&t.czData.lastMsgRecvTime, time.Now().UnixNano())
+}
+
+func (t *http2Client) getOutFlowWindow() int64 {
+	resp := make(chan uint32, 1)
+	timer := time.NewTimer(time.Second)
+	defer timer.Stop()
+	t.controlBuf.put(&outFlowControlSizeRequest{resp})
+	select {
+	case sz := <-resp:
+		return int64(sz)
+	case <-t.ctxDone:
+		return -1
+	case <-timer.C:
+		return -2
+	}
+}