Update dependencies

10 files changed, 1834 insertions, 1280 deletions

diff --git a/vendor/google.golang.org/grpc/transport/bdp_estimator.go b/vendor/google.golang.org/grpc/transport/bdp_estimator.go
new file mode 100644
index 0000000..8dd2ed4
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/bdp_estimator.go
@@ -0,0 +1,143 @@
+/*
+ *
+ * Copyright 2017 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 (
+	"sync"
+	"time"
+)
+
+const (
+	// bdpLimit is the maximum value the flow control windows
+	// will be increased to.
+	bdpLimit = (1 << 20) * 4
+	// alpha is a constant factor used to keep a moving average
+	// of RTTs.
+	alpha = 0.9
+	// If the current bdp sample is greater than or equal to
+	// our beta * our estimated bdp and the current bandwidth
+	// sample is the maximum bandwidth observed so far, we
+	// increase our bbp estimate by a factor of gamma.
+	beta = 0.66
+	// To put our bdp to be smaller than or equal to twice the real BDP,
+	// we should multiply our current sample with 4/3, however to round things out
+	// we use 2 as the multiplication factor.
+	gamma = 2
+)
+
+var (
+	// Adding arbitrary data to ping so that its ack can be
+	// identified.
+	// Easter-egg: what does the ping message say?
+	bdpPing = &ping{data: [8]byte{2, 4, 16, 16, 9, 14, 7, 7}}
+)
+
+type bdpEstimator struct {
+	// sentAt is the time when the ping was sent.
+	sentAt time.Time
+
+	mu sync.Mutex
+	// bdp is the current bdp estimate.
+	bdp uint32
+	// sample is the number of bytes received in one measurement cycle.
+	sample uint32
+	// bwMax is the maximum bandwidth noted so far (bytes/sec).
+	bwMax float64
+	// bool to keep track of the beginning of a new measurement cycle.
+	isSent bool
+	// Callback to update the window sizes.
+	updateFlowControl func(n uint32)
+	// sampleCount is the number of samples taken so far.
+	sampleCount uint64
+	// round trip time (seconds)
+	rtt float64
+}
+
+// timesnap registers the time bdp ping was sent out so that
+// network rtt can be calculated when its ack is received.
+// It is called (by controller) when the bdpPing is
+// being written on the wire.
+func (b *bdpEstimator) timesnap(d [8]byte) {
+	if bdpPing.data != d {
+		return
+	}
+	b.sentAt = time.Now()
+}
+
+// add adds bytes to the current sample for calculating bdp.
+// It returns true only if a ping must be sent. This can be used
+// by the caller (handleData) to make decision about batching
+// a window update with it.
+func (b *bdpEstimator) add(n uint32) bool {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.bdp == bdpLimit {
+		return false
+	}
+	if !b.isSent {
+		b.isSent = true
+		b.sample = n
+		b.sentAt = time.Time{}
+		b.sampleCount++
+		return true
+	}
+	b.sample += n
+	return false
+}
+
+// calculate is called when an ack for a bdp ping is received.
+// Here we calculate the current bdp and bandwidth sample and
+// decide if the flow control windows should go up.
+func (b *bdpEstimator) calculate(d [8]byte) {
+	// Check if the ping acked for was the bdp ping.
+	if bdpPing.data != d {
+		return
+	}
+	b.mu.Lock()
+	rttSample := time.Since(b.sentAt).Seconds()
+	if b.sampleCount < 10 {
+		// Bootstrap rtt with an average of first 10 rtt samples.
+		b.rtt += (rttSample - b.rtt) / float64(b.sampleCount)
+	} else {
+		// Heed to the recent past more.
+		b.rtt += (rttSample - b.rtt) * float64(alpha)
+	}
+	b.isSent = false
+	// The number of bytes accumulated so far in the sample is smaller
+	// than or equal to 1.5 times the real BDP on a saturated connection.
+	bwCurrent := float64(b.sample) / (b.rtt * float64(1.5))
+	if bwCurrent > b.bwMax {
+		b.bwMax = bwCurrent
+	}
+	// If the current sample (which is smaller than or equal to the 1.5 times the real BDP) is
+	// greater than or equal to 2/3rd our perceived bdp AND this is the maximum bandwidth seen so far, we
+	// should update our perception of the network BDP.
+	if float64(b.sample) >= beta*float64(b.bdp) && bwCurrent == b.bwMax && b.bdp != bdpLimit {
+		sampleFloat := float64(b.sample)
+		b.bdp = uint32(gamma * sampleFloat)
+		if b.bdp > bdpLimit {
+			b.bdp = bdpLimit
+		}
+		bdp := b.bdp
+		b.mu.Unlock()
+		b.updateFlowControl(bdp)
+		return
+	}
+	b.mu.Unlock()
+}
diff --git a/vendor/google.golang.org/grpc/transport/control.go b/vendor/google.golang.org/grpc/transport/control.go
index 8d29aee..dd1a8d4 100644
--- a/vendor/google.golang.org/grpc/transport/control.go
+++ b/vendor/google.golang.org/grpc/transport/control.go
@@ -1,33 +1,18 @@
 /*
  *
- * Copyright 2014, Google Inc.
- * All rights reserved.
+ * Copyright 2014 gRPC authors.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
+ * 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
  *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 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.
  *
  */
 
@@ -37,17 +22,18 @@ import (
 	"fmt"
 	"math"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/hpack"
 )
 
 const (
 	// The default value of flow control window size in HTTP2 spec.
 	defaultWindowSize = 65535
 	// The initial window size for flow control.
-	initialWindowSize             = defaultWindowSize      // for an RPC
-	initialConnWindowSize         = defaultWindowSize * 16 // for a connection
+	initialWindowSize             = defaultWindowSize // for an RPC
 	infinity                      = time.Duration(math.MaxInt64)
 	defaultClientKeepaliveTime    = infinity
 	defaultClientKeepaliveTimeout = time.Duration(20 * time.Second)
@@ -58,11 +44,43 @@ const (
 	defaultServerKeepaliveTime    = time.Duration(2 * time.Hour)
 	defaultServerKeepaliveTimeout = time.Duration(20 * time.Second)
 	defaultKeepalivePolicyMinTime = time.Duration(5 * time.Minute)
+	// max window limit set by HTTP2 Specs.
+	maxWindowSize = math.MaxInt32
+	// defaultLocalSendQuota sets is default value for number of data
+	// bytes that each stream can schedule before some of it being
+	// flushed out.
+	defaultLocalSendQuota = 64 * 1024
 )
 
 // The following defines various control items which could flow through
 // the control buffer of transport. They represent different aspects of
 // control tasks, e.g., flow control, settings, streaming resetting, etc.
+
+type headerFrame struct {
+	streamID  uint32
+	hf        []hpack.HeaderField
+	endStream bool
+}
+
+func (*headerFrame) item() {}
+
+type continuationFrame struct {
+	streamID            uint32
+	endHeaders          bool
+	headerBlockFragment []byte
+}
+
+type dataFrame struct {
+	streamID  uint32
+	endStream bool
+	d         []byte
+	f         func()
+}
+
+func (*dataFrame) item() {}
+
+func (*continuationFrame) item() {}
+
 type windowUpdate struct {
 	streamID  uint32
 	increment uint32
@@ -87,6 +105,8 @@ func (*resetStream) item() {}
 type goAway struct {
 	code      http2.ErrCode
 	debugData []byte
+	headsUp   bool
+	closeConn bool
 }
 
 func (*goAway) item() {}
@@ -108,8 +128,9 @@ func (*ping) item() {}
 type quotaPool struct {
 	c chan int
 
-	mu    sync.Mutex
-	quota int
+	mu      sync.Mutex
+	version uint32
+	quota   int
 }
 
 // newQuotaPool creates a quotaPool which has quota q available to consume.
@@ -130,6 +151,10 @@ func newQuotaPool(q int) *quotaPool {
 func (qb *quotaPool) add(v int) {
 	qb.mu.Lock()
 	defer qb.mu.Unlock()
+	qb.lockedAdd(v)
+}
+
+func (qb *quotaPool) lockedAdd(v int) {
 	select {
 	case n := <-qb.c:
 		qb.quota += n
@@ -150,6 +175,35 @@ func (qb *quotaPool) add(v int) {
 	}
 }
 
+func (qb *quotaPool) addAndUpdate(v int) {
+	qb.mu.Lock()
+	defer qb.mu.Unlock()
+	qb.lockedAdd(v)
+	// Update the version only after having added to the quota
+	// so that if acquireWithVesrion sees the new vesrion it is
+	// guaranteed to have seen the updated quota.
+	// Also, still keep this inside of the lock, so that when
+	// compareAndExecute is processing, this function doesn't
+	// get executed partially (quota gets updated but the version
+	// doesn't).
+	atomic.AddUint32(&(qb.version), 1)
+}
+
+func (qb *quotaPool) acquireWithVersion() (<-chan int, uint32) {
+	return qb.c, atomic.LoadUint32(&(qb.version))
+}
+
+func (qb *quotaPool) compareAndExecute(version uint32, success, failure func()) bool {
+	qb.mu.Lock()
+	defer qb.mu.Unlock()
+	if version == atomic.LoadUint32(&(qb.version)) {
+		success()
+		return true
+	}
+	failure()
+	return false
+}
+
 // acquire returns the channel on which available quota amounts are sent.
 func (qb *quotaPool) acquire() <-chan int {
 	return qb.c
@@ -157,16 +211,59 @@ func (qb *quotaPool) acquire() <-chan int {
 
 // inFlow deals with inbound flow control
 type inFlow struct {
+	mu sync.Mutex
 	// The inbound flow control limit for pending data.
 	limit uint32
-
-	mu sync.Mutex
 	// pendingData is the overall data which have been received but not been
 	// consumed by applications.
 	pendingData uint32
 	// The amount of data the application has consumed but grpc has not sent
 	// window update for them. Used to reduce window update frequency.
 	pendingUpdate uint32
+	// delta is the extra window update given by receiver when an application
+	// is reading data bigger in size than the inFlow limit.
+	delta uint32
+}
+
+// newLimit updates the inflow window to a new value n.
+// It assumes that n is always greater than the old limit.
+func (f *inFlow) newLimit(n uint32) uint32 {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	d := n - f.limit
+	f.limit = n
+	return d
+}
+
+func (f *inFlow) maybeAdjust(n uint32) uint32 {
+	if n > uint32(math.MaxInt32) {
+		n = uint32(math.MaxInt32)
+	}
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	// estSenderQuota is the receiver's view of the maximum number of bytes the sender
+	// can send without a window update.
+	estSenderQuota := int32(f.limit - (f.pendingData + f.pendingUpdate))
+	// estUntransmittedData is the maximum number of bytes the sends might not have put
+	// on the wire yet. A value of 0 or less means that we have already received all or
+	// more bytes than the application is requesting to read.
+	estUntransmittedData := int32(n - f.pendingData) // Casting into int32 since it could be negative.
+	// This implies that unless we send a window update, the sender won't be able to send all the bytes
+	// for this message. Therefore we must send an update over the limit since there's an active read
+	// request from the application.
+	if estUntransmittedData > estSenderQuota {
+		// Sender's window shouldn't go more than 2^31 - 1 as speecified in the HTTP spec.
+		if f.limit+n > maxWindowSize {
+			f.delta = maxWindowSize - f.limit
+		} else {
+			// Send a window update for the whole message and not just the difference between
+			// estUntransmittedData and estSenderQuota. This will be helpful in case the message
+			// is padded; We will fallback on the current available window(at least a 1/4th of the limit).
+			f.delta = n
+		}
+		return f.delta
+	}
+	return 0
 }
 
 // onData is invoked when some data frame is received. It updates pendingData.
@@ -174,7 +271,7 @@ func (f *inFlow) onData(n uint32) error {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	f.pendingData += n
-	if f.pendingData+f.pendingUpdate > f.limit {
+	if f.pendingData+f.pendingUpdate > f.limit+f.delta {
 		return fmt.Errorf("received %d-bytes data exceeding the limit %d bytes", f.pendingData+f.pendingUpdate, f.limit)
 	}
 	return nil
@@ -189,6 +286,13 @@ func (f *inFlow) onRead(n uint32) uint32 {
 		return 0
 	}
 	f.pendingData -= n
+	if n > f.delta {
+		n -= f.delta
+		f.delta = 0
+	} else {
+		f.delta -= n
+		n = 0
+	}
 	f.pendingUpdate += n
 	if f.pendingUpdate >= f.limit/4 {
 		wu := f.pendingUpdate
@@ -198,10 +302,10 @@ func (f *inFlow) onRead(n uint32) uint32 {
 	return 0
 }
 
-func (f *inFlow) resetPendingData() uint32 {
+func (f *inFlow) resetPendingUpdate() uint32 {
 	f.mu.Lock()
 	defer f.mu.Unlock()
-	n := f.pendingData
-	f.pendingData = 0
+	n := f.pendingUpdate
+	f.pendingUpdate = 0
 	return n
 }
diff --git a/vendor/google.golang.org/grpc/transport/go16.go b/vendor/google.golang.org/grpc/transport/go16.go
deleted file mode 100644
index ee1c46b..0000000
--- a/vendor/google.golang.org/grpc/transport/go16.go
+++ /dev/null
@@ -1,46 +0,0 @@
-// +build go1.6,!go1.7
-
-/*
- * Copyright 2016, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-package transport
-
-import (
-	"net"
-
-	"golang.org/x/net/context"
-)
-
-// dialContext connects to the address on the named network.
-func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
-	return (&net.Dialer{Cancel: ctx.Done()}).Dial(network, address)
-}
diff --git a/vendor/google.golang.org/grpc/transport/go17.go b/vendor/google.golang.org/grpc/transport/go17.go
deleted file mode 100644
index 356f13f..0000000
--- a/vendor/google.golang.org/grpc/transport/go17.go
+++ /dev/null
@@ -1,46 +0,0 @@
-// +build go1.7
-
-/*
- * Copyright 2016, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-package transport
-
-import (
-	"net"
-
-	"golang.org/x/net/context"
-)
-
-// dialContext connects to the address on the named network.
-func dialContext(ctx context.Context, network, address string) (net.Conn, error) {
-	return (&net.Dialer{}).DialContext(ctx, network, address)
-}
diff --git a/vendor/google.golang.org/grpc/transport/handler_server.go b/vendor/google.golang.org/grpc/transport/handler_server.go
index 28c9ce0..f1f6caf 100644
--- a/vendor/google.golang.org/grpc/transport/handler_server.go
+++ b/vendor/google.golang.org/grpc/transport/handler_server.go
@@ -1,32 +1,18 @@
 /*
- * Copyright 2016, Google Inc.
- * All rights reserved.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
+ * Copyright 2016 gRPC authors.
  *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
+ * 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
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *     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.
  *
  */
 
@@ -47,6 +33,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/golang/protobuf/proto"
 	"golang.org/x/net/context"
 	"golang.org/x/net/http2"
 	"google.golang.org/grpc/codes"
@@ -102,14 +89,9 @@ func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request) (ServerTr
 			continue
 		}
 		for _, v := range vv {
-			if k == "user-agent" {
-				// user-agent is special. Copying logic of http_util.go.
-				if i := strings.LastIndex(v, " "); i == -1 {
-					// There is no application user agent string being set
-					continue
-				} else {
-					v = v[:i]
-				}
+			v, err := decodeMetadataHeader(k, v)
+			if err != nil {
+				return nil, streamErrorf(codes.InvalidArgument, "malformed binary metadata: %v", err)
 			}
 			metakv = append(metakv, k, v)
 		}
@@ -140,6 +122,11 @@ type serverHandlerTransport struct {
 	// ServeHTTP (HandleStreams) goroutine. The channel is closed
 	// when WriteStatus is called.
 	writes chan func()
+
+	mu sync.Mutex
+	// streamDone indicates whether WriteStatus has been called and writes channel
+	// has been closed.
+	streamDone bool
 }
 
 func (ht *serverHandlerTransport) Close() error {
@@ -175,15 +162,28 @@ func (a strAddr) String() string { return string(a) }
 
 // do runs fn in the ServeHTTP goroutine.
 func (ht *serverHandlerTransport) do(fn func()) error {
+	// Avoid a panic writing to closed channel. Imperfect but maybe good enough.
 	select {
-	case ht.writes <- fn:
-		return nil
 	case <-ht.closedCh:
 		return ErrConnClosing
+	default:
+		select {
+		case ht.writes <- fn:
+			return nil
+		case <-ht.closedCh:
+			return ErrConnClosing
+		}
 	}
 }
 
 func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) error {
+	ht.mu.Lock()
+	if ht.streamDone {
+		ht.mu.Unlock()
+		return nil
+	}
+	ht.streamDone = true
+	ht.mu.Unlock()
 	err := ht.do(func() {
 		ht.writeCommonHeaders(s)
 
@@ -198,7 +198,15 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) erro
 			h.Set("Grpc-Message", encodeGrpcMessage(m))
 		}
 
-		// TODO: Support Grpc-Status-Details-Bin
+		if p := st.Proto(); p != nil && len(p.Details) > 0 {
+			stBytes, err := proto.Marshal(p)
+			if err != nil {
+				// TODO: return error instead, when callers are able to handle it.
+				panic(err)
+			}
+
+			h.Set("Grpc-Status-Details-Bin", encodeBinHeader(stBytes))
+		}
 
 		if md := s.Trailer(); len(md) > 0 {
 			for k, vv := range md {
@@ -207,10 +215,9 @@ func (ht *serverHandlerTransport) WriteStatus(s *Stream, st *status.Status) erro
 					continue
 				}
 				for _, v := range vv {
-					// http2 ResponseWriter mechanism to
-					// send undeclared Trailers after the
-					// headers have possibly been written.
-					h.Add(http2.TrailerPrefix+k, v)
+					// http2 ResponseWriter mechanism to send undeclared Trailers after
+					// the headers have possibly been written.
+					h.Add(http2.TrailerPrefix+k, encodeMetadataHeader(k, v))
 				}
 			}
 		}
@@ -238,16 +245,17 @@ func (ht *serverHandlerTransport) writeCommonHeaders(s *Stream) {
 	// and https://golang.org/pkg/net/http/#example_ResponseWriter_trailers
 	h.Add("Trailer", "Grpc-Status")
 	h.Add("Trailer", "Grpc-Message")
-	// TODO: Support Grpc-Status-Details-Bin
+	h.Add("Trailer", "Grpc-Status-Details-Bin")
 
 	if s.sendCompress != "" {
 		h.Set("Grpc-Encoding", s.sendCompress)
 	}
 }
 
-func (ht *serverHandlerTransport) Write(s *Stream, data []byte, opts *Options) error {
+func (ht *serverHandlerTransport) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
 	return ht.do(func() {
 		ht.writeCommonHeaders(s)
+		ht.rw.Write(hdr)
 		ht.rw.Write(data)
 		if !opts.Delay {
 			ht.rw.(http.Flusher).Flush()
@@ -265,6 +273,7 @@ func (ht *serverHandlerTransport) WriteHeader(s *Stream, md metadata.MD) error {
 				continue
 			}
 			for _, v := range vv {
+				v = encodeMetadataHeader(k, v)
 				h.Add(k, v)
 			}
 		}
@@ -305,13 +314,13 @@ func (ht *serverHandlerTransport) HandleStreams(startStream func(*Stream), trace
 	req := ht.req
 
 	s := &Stream{
-		id:            0,            // irrelevant
-		windowHandler: func(int) {}, // nothing
-		cancel:        cancel,
-		buf:           newRecvBuffer(),
-		st:            ht,
-		method:        req.URL.Path,
-		recvCompress:  req.Header.Get("grpc-encoding"),
+		id:           0, // irrelevant
+		requestRead:  func(int) {},
+		cancel:       cancel,
+		buf:          newRecvBuffer(),
+		st:           ht,
+		method:       req.URL.Path,
+		recvCompress: req.Header.Get("grpc-encoding"),
 	}
 	pr := &peer.Peer{
 		Addr: ht.RemoteAddr(),
@@ -322,7 +331,10 @@ func (ht *serverHandlerTransport) HandleStreams(startStream func(*Stream), trace
 	ctx = metadata.NewIncomingContext(ctx, ht.headerMD)
 	ctx = peer.NewContext(ctx, pr)
 	s.ctx = newContextWithStream(ctx, s)
-	s.dec = &recvBufferReader{ctx: s.ctx, recv: s.buf}
+	s.trReader = &transportReader{
+		reader:        &recvBufferReader{ctx: s.ctx, recv: s.buf},
+		windowHandler: func(int) {},
+	}
 
 	// readerDone is closed when the Body.Read-ing goroutine exits.
 	readerDone := make(chan struct{})
@@ -334,11 +346,11 @@ func (ht *serverHandlerTransport) HandleStreams(startStream func(*Stream), trace
 		for buf := make([]byte, readSize); ; {
 			n, err := req.Body.Read(buf)
 			if n > 0 {
-				s.buf.put(&recvMsg{data: buf[:n:n]})
+				s.buf.put(recvMsg{data: buf[:n:n]})
 				buf = buf[n:]
 			}
 			if err != nil {
-				s.buf.put(&recvMsg{err: mapRecvMsgError(err)})
+				s.buf.put(recvMsg{err: mapRecvMsgError(err)})
 				return
 			}
 			if len(buf) == 0 {
diff --git a/vendor/google.golang.org/grpc/transport/http2_client.go b/vendor/google.golang.org/grpc/transport/http2_client.go
index 5fc6b75..6ca6cc6 100644
--- a/vendor/google.golang.org/grpc/transport/http2_client.go
+++ b/vendor/google.golang.org/grpc/transport/http2_client.go
@@ -1,33 +1,18 @@
 /*
  *
- * Copyright 2014, Google Inc.
- * All rights reserved.
+ * Copyright 2014 gRPC authors.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
+ * 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
  *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 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.
  *
  */
 
@@ -48,7 +33,6 @@ import (
 	"golang.org/x/net/http2/hpack"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
-	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
@@ -59,6 +43,7 @@ import (
 // http2Client implements the ClientTransport interface with HTTP2.
 type http2Client struct {
 	ctx        context.Context
+	cancel     context.CancelFunc
 	target     string // server name/addr
 	userAgent  string
 	md         interface{}
@@ -68,17 +53,6 @@ type http2Client struct {
 	authInfo   credentials.AuthInfo // auth info about the connection
 	nextID     uint32               // the next stream ID to be used
 
-	// writableChan synchronizes write access to the transport.
-	// A writer acquires the write lock by sending a value on writableChan
-	// and releases it by receiving from writableChan.
-	writableChan chan int
-	// shutdownChan is closed when Close is called.
-	// Blocking operations should select on shutdownChan to avoid
-	// blocking forever after Close.
-	// TODO(zhaoq): Maybe have a channel context?
-	shutdownChan chan struct{}
-	// errorChan is closed to notify the I/O error to the caller.
-	errorChan chan struct{}
 	// goAway is closed to notify the upper layer (i.e., addrConn.transportMonitor)
 	// that the server sent GoAway on this transport.
 	goAway chan struct{}
@@ -91,7 +65,7 @@ type http2Client struct {
 
 	// controlBuf delivers all the control related tasks (e.g., window
 	// updates, reset streams, and various settings) to the controller.
-	controlBuf *recvBuffer
+	controlBuf *controlBuffer
 	fc         *inFlow
 	// sendQuotaPool provides flow control to outbound message.
 	sendQuotaPool *quotaPool
@@ -101,6 +75,8 @@ type http2Client struct {
 	// The scheme used: https if TLS is on, http otherwise.
 	scheme string
 
+	isSecure bool
+
 	creds []credentials.PerRPCCredentials
 
 	// Boolean to keep track of reading activity on transport.
@@ -110,6 +86,11 @@ type http2Client struct {
 
 	statsHandler stats.Handler
 
+	initialWindowSize int32
+
+	bdpEst          *bdpEstimator
+	outQuotaVersion uint32
+
 	mu            sync.Mutex     // guard the following variables
 	state         transportState // the state of underlying connection
 	activeStreams map[uint32]*Stream
@@ -117,17 +98,18 @@ type http2Client struct {
 	maxStreams int
 	// the per-stream outbound flow control window size set by the peer.
 	streamSendQuota uint32
-	// goAwayID records the Last-Stream-ID in the GoAway frame from the server.
-	goAwayID uint32
 	// 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
 }
 
 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 dialContext(ctx, "tcp", addr)
+	return (&net.Dialer{}).DialContext(ctx, "tcp", addr)
 }
 
 func isTemporary(err error) bool {
@@ -161,14 +143,23 @@ func isTemporary(err error) bool {
 // 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(ctx context.Context, addr TargetInfo, opts ConnectOptions) (_ ClientTransport, err error) {
+func newHTTP2Client(ctx context.Context, addr TargetInfo, opts ConnectOptions, timeout time.Duration) (_ ClientTransport, err error) {
 	scheme := "http"
-	conn, err := dial(ctx, opts.Dialer, addr.Addr)
+	ctx, cancel := context.WithCancel(ctx)
+	connectCtx, connectCancel := context.WithTimeout(ctx, timeout)
+	defer func() {
+		connectCancel()
+		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: %v", err)
+			return nil, connectionErrorf(isTemporary(err), err, "transport: error while dialing: %v", err)
 		}
-		return nil, connectionErrorf(true, err, "transport: %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) {
@@ -176,16 +167,20 @@ func newHTTP2Client(ctx context.Context, addr TargetInfo, opts ConnectOptions) (
 			conn.Close()
 		}
 	}(conn)
-	var authInfo credentials.AuthInfo
+	var (
+		isSecure bool
+		authInfo credentials.AuthInfo
+	)
 	if creds := opts.TransportCredentials; creds != nil {
 		scheme = "https"
-		conn, authInfo, err = creds.ClientHandshake(ctx, addr.Addr, conn)
+		conn, authInfo, err = creds.ClientHandshake(connectCtx, addr.Addr, conn)
 		if err != nil {
 			// Credentials handshake errors are typically considered permanent
 			// to avoid retrying on e.g. bad certificates.
 			temp := isTemporary(err)
-			return nil, connectionErrorf(temp, err, "transport: %v", err)
+			return nil, connectionErrorf(temp, err, "transport: authentication handshake failed: %v", err)
 		}
+		isSecure = true
 	}
 	kp := opts.KeepaliveParams
 	// Validate keepalive parameters.
@@ -195,9 +190,24 @@ func newHTTP2Client(ctx context.Context, addr TargetInfo, opts ConnectOptions) (
 	if kp.Timeout == 0 {
 		kp.Timeout = defaultClientKeepaliveTimeout
 	}
+	dynamicWindow := true
+	icwz := int32(initialWindowSize)
+	if opts.InitialConnWindowSize >= defaultWindowSize {
+		icwz = opts.InitialConnWindowSize
+		dynamicWindow = false
+	}
 	var buf bytes.Buffer
+	writeBufSize := defaultWriteBufSize
+	if opts.WriteBufferSize > 0 {
+		writeBufSize = opts.WriteBufferSize
+	}
+	readBufSize := defaultReadBufSize
+	if opts.ReadBufferSize > 0 {
+		readBufSize = opts.ReadBufferSize
+	}
 	t := &http2Client{
 		ctx:        ctx,
+		cancel:     cancel,
 		target:     addr.Addr,
 		userAgent:  opts.UserAgent,
 		md:         addr.Metadata,
@@ -206,27 +216,36 @@ func newHTTP2Client(ctx context.Context, addr TargetInfo, opts ConnectOptions) (
 		localAddr:  conn.LocalAddr(),
 		authInfo:   authInfo,
 		// The client initiated stream id is odd starting from 1.
-		nextID:          1,
-		writableChan:    make(chan int, 1),
-		shutdownChan:    make(chan struct{}),
-		errorChan:       make(chan struct{}),
-		goAway:          make(chan struct{}),
-		awakenKeepalive: make(chan struct{}, 1),
-		framer:          newFramer(conn),
-		hBuf:            &buf,
-		hEnc:            hpack.NewEncoder(&buf),
-		controlBuf:      newRecvBuffer(),
-		fc:              &inFlow{limit: initialConnWindowSize},
-		sendQuotaPool:   newQuotaPool(defaultWindowSize),
-		scheme:          scheme,
-		state:           reachable,
-		activeStreams:   make(map[uint32]*Stream),
-		creds:           opts.PerRPCCredentials,
-		maxStreams:      defaultMaxStreamsClient,
-		streamsQuota:    newQuotaPool(defaultMaxStreamsClient),
-		streamSendQuota: defaultWindowSize,
-		kp:              kp,
-		statsHandler:    opts.StatsHandler,
+		nextID:            1,
+		goAway:            make(chan struct{}),
+		awakenKeepalive:   make(chan struct{}, 1),
+		hBuf:              &buf,
+		hEnc:              hpack.NewEncoder(&buf),
+		framer:            newFramer(conn, writeBufSize, readBufSize),
+		controlBuf:        newControlBuffer(),
+		fc:                &inFlow{limit: uint32(icwz)},
+		sendQuotaPool:     newQuotaPool(defaultWindowSize),
+		scheme:            scheme,
+		state:             reachable,
+		activeStreams:     make(map[uint32]*Stream),
+		isSecure:          isSecure,
+		creds:             opts.PerRPCCredentials,
+		maxStreams:        defaultMaxStreamsClient,
+		streamsQuota:      newQuotaPool(defaultMaxStreamsClient),
+		streamSendQuota:   defaultWindowSize,
+		kp:                kp,
+		statsHandler:      opts.StatsHandler,
+		initialWindowSize: initialWindowSize,
+	}
+	if opts.InitialWindowSize >= defaultWindowSize {
+		t.initialWindowSize = opts.InitialWindowSize
+		dynamicWindow = false
+	}
+	if dynamicWindow {
+		t.bdpEst = &bdpEstimator{
+			bdp:               initialWindowSize,
+			updateFlowControl: t.updateFlowControl,
+		}
 	}
 	// Make sure awakenKeepalive can't be written upon.
 	// keepalive routine will make it writable, if need be.
@@ -249,65 +268,75 @@ func newHTTP2Client(ctx context.Context, addr TargetInfo, opts ConnectOptions) (
 	n, err := t.conn.Write(clientPreface)
 	if err != nil {
 		t.Close()
-		return nil, connectionErrorf(true, err, "transport: %v", err)
+		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))
 	}
-	if initialWindowSize != defaultWindowSize {
-		err = t.framer.writeSettings(true, http2.Setting{
+	if t.initialWindowSize != defaultWindowSize {
+		err = t.framer.fr.WriteSettings(http2.Setting{
 			ID:  http2.SettingInitialWindowSize,
-			Val: uint32(initialWindowSize),
+			Val: uint32(t.initialWindowSize),
 		})
 	} else {
-		err = t.framer.writeSettings(true)
+		err = t.framer.fr.WriteSettings()
 	}
 	if err != nil {
 		t.Close()
-		return nil, connectionErrorf(true, err, "transport: %v", err)
+		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(initialConnWindowSize - defaultWindowSize); delta > 0 {
-		if err := t.framer.writeWindowUpdate(true, 0, delta); err != nil {
+	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: %v", err)
+			return nil, connectionErrorf(true, err, "transport: failed to write window update: %v", err)
 		}
 	}
-	go t.controller()
+	t.framer.writer.Flush()
+	go func() {
+		loopyWriter(t.ctx, t.controlBuf, t.itemHandler)
+		t.Close()
+	}()
 	if t.kp.Time != infinity {
 		go t.keepalive()
 	}
-	t.writableChan <- 0
 	return t, nil
 }
 
 func (t *http2Client) newStream(ctx context.Context, callHdr *CallHdr) *Stream {
 	// TODO(zhaoq): Handle uint32 overflow of Stream.id.
 	s := &Stream{
-		id:            t.nextID,
-		done:          make(chan struct{}),
-		goAway:        make(chan struct{}),
-		method:        callHdr.Method,
-		sendCompress:  callHdr.SendCompress,
-		buf:           newRecvBuffer(),
-		fc:            &inFlow{limit: initialWindowSize},
-		sendQuotaPool: newQuotaPool(int(t.streamSendQuota)),
-		headerChan:    make(chan struct{}),
+		id:             t.nextID,
+		done:           make(chan struct{}),
+		goAway:         make(chan struct{}),
+		method:         callHdr.Method,
+		sendCompress:   callHdr.SendCompress,
+		buf:            newRecvBuffer(),
+		fc:             &inFlow{limit: uint32(t.initialWindowSize)},
+		sendQuotaPool:  newQuotaPool(int(t.streamSendQuota)),
+		localSendQuota: newQuotaPool(defaultLocalSendQuota),
+		headerChan:     make(chan struct{}),
 	}
 	t.nextID += 2
-	s.windowHandler = func(n int) {
-		t.updateWindow(s, uint32(n))
+	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.dec = &recvBufferReader{
-		ctx:    s.ctx,
-		goAway: s.goAway,
-		recv:   s.buf,
+	s.trReader = &transportReader{
+		reader: &recvBufferReader{
+			ctx:    s.ctx,
+			goAway: s.goAway,
+			recv:   s.buf,
+		},
+		windowHandler: func(n int) {
+			t.updateWindow(s, uint32(n))
+		},
 	}
+
 	return s
 }
 
@@ -321,31 +350,51 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Strea
 	if t.authInfo != nil {
 		pr.AuthInfo = t.authInfo
 	}
-	userCtx := ctx
 	ctx = peer.NewContext(ctx, pr)
-	authData := make(map[string]string)
-	for _, c := range t.creds {
+	var (
+		authData = make(map[string]string)
+		audience string
+	)
+	// Create an audience string only if needed.
+	if len(t.creds) > 0 || callHdr.Creds != nil {
 		// Construct URI required to get auth request metadata.
-		var port string
-		if pos := strings.LastIndex(t.target, ":"); pos != -1 {
-			// Omit port if it is the default one.
-			if t.target[pos+1:] != "443" {
-				port = ":" + t.target[pos+1:]
-			}
-		}
+		// Omit port if it is the default one.
+		host := strings.TrimSuffix(callHdr.Host, ":443")
 		pos := strings.LastIndex(callHdr.Method, "/")
 		if pos == -1 {
-			return nil, streamErrorf(codes.InvalidArgument, "transport: malformed method name: %q", callHdr.Method)
+			pos = len(callHdr.Method)
 		}
-		audience := "https://" + callHdr.Host + port + callHdr.Method[:pos]
+		audience = "https://" + host + callHdr.Method[:pos]
+	}
+	for _, c := range t.creds {
 		data, err := c.GetRequestMetadata(ctx, audience)
 		if err != nil {
-			return nil, streamErrorf(codes.InvalidArgument, "transport: %v", err)
+			return nil, streamErrorf(codes.Internal, "transport: %v", err)
 		}
 		for k, v := range data {
+			// Capital header names are illegal in HTTP/2.
+			k = strings.ToLower(k)
 			authData[k] = v
 		}
 	}
+	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, streamErrorf(codes.Unauthenticated, "transport: cannot send secure credentials on an insecure connection")
+		}
+		data, err := callCreds.GetRequestMetadata(ctx, audience)
+		if err != nil {
+			return nil, streamErrorf(codes.Internal, "transport: %v", err)
+		}
+		for k, v := range data {
+			// Capital header names are illegal in HTTP/2
+			k = strings.ToLower(k)
+			callAuthData[k] = v
+		}
+	}
 	t.mu.Lock()
 	if t.activeStreams == nil {
 		t.mu.Unlock()
@@ -360,7 +409,7 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Strea
 		return nil, ErrConnClosing
 	}
 	t.mu.Unlock()
-	sq, err := wait(ctx, nil, nil, t.shutdownChan, t.streamsQuota.acquire())
+	sq, err := wait(ctx, t.ctx, nil, nil, t.streamsQuota.acquire())
 	if err != nil {
 		return nil, err
 	}
@@ -368,140 +417,108 @@ func (t *http2Client) NewStream(ctx context.Context, callHdr *CallHdr) (_ *Strea
 	if sq > 1 {
 		t.streamsQuota.add(sq - 1)
 	}
-	if _, err := wait(ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
-		// Return the quota back now because there is no stream returned to the caller.
-		if _, ok := err.(StreamError); ok {
-			t.streamsQuota.add(1)
-		}
-		return nil, err
-	}
-	t.mu.Lock()
-	if t.state == draining {
-		t.mu.Unlock()
-		t.streamsQuota.add(1)
-		// Need to make t writable again so that the rpc in flight can still proceed.
-		t.writableChan <- 0
-		return nil, ErrStreamDrain
-	}
-	if t.state != reachable {
-		t.mu.Unlock()
-		return nil, ErrConnClosing
-	}
-	s := t.newStream(ctx, callHdr)
-	s.clientStatsCtx = userCtx
-	t.activeStreams[s.id] = s
-	// If the number of active streams change from 0 to 1, then check if keepalive
-	// has gone dormant. If so, wake it up.
-	if len(t.activeStreams) == 1 {
-		select {
-		case t.awakenKeepalive <- struct{}{}:
-			t.framer.writePing(false, false, [8]byte{})
-		default:
-		}
-	}
-
-	t.mu.Unlock()
-
-	// HPACK encodes various headers. Note that once WriteField(...) is
-	// called, the corresponding headers/continuation frame has to be sent
-	// because hpack.Encoder is stateful.
-	t.hBuf.Reset()
-	t.hEnc.WriteField(hpack.HeaderField{Name: ":method", Value: "POST"})
-	t.hEnc.WriteField(hpack.HeaderField{Name: ":scheme", Value: t.scheme})
-	t.hEnc.WriteField(hpack.HeaderField{Name: ":path", Value: callHdr.Method})
-	t.hEnc.WriteField(hpack.HeaderField{Name: ":authority", Value: callHdr.Host})
-	t.hEnc.WriteField(hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
-	t.hEnc.WriteField(hpack.HeaderField{Name: "user-agent", Value: t.userAgent})
-	t.hEnc.WriteField(hpack.HeaderField{Name: "te", Value: "trailers"})
+	// TODO(mmukhi): Benchmark if the perfomance 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: "application/grpc"})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "user-agent", Value: t.userAgent})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "te", Value: "trailers"})
 
 	if callHdr.SendCompress != "" {
-		t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-encoding", Value: 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 := dl.Sub(time.Now())
-		t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-timeout", Value: encodeTimeout(timeout)})
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-timeout", Value: encodeTimeout(timeout)})
 	}
-
 	for k, v := range authData {
-		// Capital header names are illegal in HTTP/2.
-		k = strings.ToLower(k)
-		t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: v})
+		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)})
 	}
-	var (
-		hasMD      bool
-		endHeaders bool
-	)
 	if md, ok := metadata.FromOutgoingContext(ctx); ok {
-		hasMD = true
-		for k, v := range md {
+		for k, vv := range md {
 			// HTTP doesn't allow you to set pseudoheaders after non pseudoheaders were set.
 			if isReservedHeader(k) {
 				continue
 			}
-			for _, entry := range v {
-				t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
+			for _, v := range vv {
+				headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
 			}
 		}
 	}
 	if md, ok := t.md.(*metadata.MD); ok {
-		for k, v := range *md {
+		for k, vv := range *md {
 			if isReservedHeader(k) {
 				continue
 			}
-			for _, entry := range v {
-				t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
+			for _, v := range vv {
+				headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
 			}
 		}
 	}
-	first := true
-	bufLen := t.hBuf.Len()
-	// Sends the headers in a single batch even when they span multiple frames.
-	for !endHeaders {
-		size := t.hBuf.Len()
-		if size > http2MaxFrameLen {
-			size = http2MaxFrameLen
-		} else {
-			endHeaders = true
-		}
-		var flush bool
-		if endHeaders && (hasMD || callHdr.Flush) {
-			flush = true
-		}
-		if first {
-			// Sends a HeadersFrame to server to start a new stream.
-			p := http2.HeadersFrameParam{
-				StreamID:      s.id,
-				BlockFragment: t.hBuf.Next(size),
-				EndStream:     false,
-				EndHeaders:    endHeaders,
-			}
-			// Do a force flush for the buffered frames iff it is the last headers frame
-			// and there is header metadata to be sent. Otherwise, there is flushing until
-			// the corresponding data frame is written.
-			err = t.framer.writeHeaders(flush, p)
-			first = false
-		} else {
-			// Sends Continuation frames for the leftover headers.
-			err = t.framer.writeContinuation(flush, s.id, endHeaders, t.hBuf.Next(size))
-		}
-		if err != nil {
-			t.notifyError(err)
-			return nil, connectionErrorf(true, err, "transport: %v", err)
+	t.mu.Lock()
+	if t.state == draining {
+		t.mu.Unlock()
+		t.streamsQuota.add(1)
+		return nil, ErrStreamDrain
+	}
+	if t.state != reachable {
+		t.mu.Unlock()
+		return nil, ErrConnClosing
+	}
+	s := t.newStream(ctx, callHdr)
+	t.activeStreams[s.id] = s
+	// If the number of active streams change from 0 to 1, then check if keepalive
+	// has gone dormant. If so, wake it up.
+	if len(t.activeStreams) == 1 {
+		select {
+		case t.awakenKeepalive <- struct{}{}:
+			t.controlBuf.put(&ping{data: [8]byte{}})
+			// Fill the awakenKeepalive channel again as this channel must be
+			// kept non-writable except at the point that the keepalive()
+			// goroutine is waiting either to be awaken or shutdown.
+			t.awakenKeepalive <- struct{}{}
+		default:
 		}
 	}
+	t.controlBuf.put(&headerFrame{
+		streamID:  s.id,
+		hf:        headerFields,
+		endStream: false,
+	})
+	t.mu.Unlock()
+
+	s.mu.Lock()
+	s.bytesSent = true
+	s.mu.Unlock()
+
 	if t.statsHandler != nil {
 		outHeader := &stats.OutHeader{
 			Client:      true,
-			WireLength:  bufLen,
 			FullMethod:  callHdr.Method,
 			RemoteAddr:  t.remoteAddr,
 			LocalAddr:   t.localAddr,
 			Compression: callHdr.SendCompress,
 		}
-		t.statsHandler.HandleRPC(s.clientStatsCtx, outHeader)
+		t.statsHandler.HandleRPC(s.ctx, outHeader)
 	}
-	t.writableChan <- 0
 	return s, nil
 }
 
@@ -513,6 +530,10 @@ func (t *http2Client) CloseStream(s *Stream, err error) {
 		t.mu.Unlock()
 		return
 	}
+	if err != nil {
+		// notify in-flight streams, before the deletion
+		s.write(recvMsg{err: err})
+	}
 	delete(t.activeStreams, s.id)
 	if t.state == draining && len(t.activeStreams) == 0 {
 		// The transport is draining and s is the last live stream on t.
@@ -542,11 +563,6 @@ func (t *http2Client) CloseStream(s *Stream, err error) {
 	s.mu.Lock()
 	rstStream = s.rstStream
 	rstError = s.rstError
-	if q := s.fc.resetPendingData(); q > 0 {
-		if n := t.fc.onRead(q); n > 0 {
-			t.controlBuf.put(&windowUpdate{0, n})
-		}
-	}
 	if s.state == streamDone {
 		s.mu.Unlock()
 		return
@@ -572,12 +588,9 @@ func (t *http2Client) Close() (err error) {
 		t.mu.Unlock()
 		return
 	}
-	if t.state == reachable || t.state == draining {
-		close(t.errorChan)
-	}
 	t.state = closing
 	t.mu.Unlock()
-	close(t.shutdownChan)
+	t.cancel()
 	err = t.conn.Close()
 	t.mu.Lock()
 	streams := t.activeStreams
@@ -599,41 +612,18 @@ func (t *http2Client) Close() (err error) {
 		}
 		t.statsHandler.HandleConn(t.ctx, connEnd)
 	}
-	return
+	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() error {
 	t.mu.Lock()
 	switch t.state {
-	case unreachable:
-		// The server may close the connection concurrently. t is not available for
-		// any streams. Close it now.
-		t.mu.Unlock()
-		t.Close()
-		return nil
-	case closing:
-		t.mu.Unlock()
-		return nil
-	}
-	// Notify the streams which were initiated after the server sent GOAWAY.
-	select {
-	case <-t.goAway:
-		n := t.prevGoAwayID
-		if n == 0 && t.nextID > 1 {
-			n = t.nextID - 2
-		}
-		m := t.goAwayID + 2
-		if m == 2 {
-			m = 1
-		}
-		for i := m; i <= n; i += 2 {
-			if s, ok := t.activeStreams[i]; ok {
-				close(s.goAway)
-			}
-		}
-	default:
-	}
-	if t.state == draining {
+	case closing, draining:
 		t.mu.Unlock()
 		return nil
 	}
@@ -648,21 +638,38 @@ func (t *http2Client) GracefulClose() error {
 
 // Write formats the data into HTTP2 data frame(s) and sends it out. The caller
 // should proceed only if Write returns nil.
-// TODO(zhaoq): opts.Delay is ignored in this implementation. Support it later
-// if it improves the performance.
-func (t *http2Client) Write(s *Stream, data []byte, opts *Options) error {
-	r := bytes.NewBuffer(data)
-	for {
-		var p []byte
-		if r.Len() > 0 {
+func (t *http2Client) Write(s *Stream, hdr []byte, data []byte, opts *Options) error {
+	select {
+	case <-s.ctx.Done():
+		return ContextErr(s.ctx.Err())
+	case <-t.ctx.Done():
+		return ErrConnClosing
+	default:
+	}
+
+	if hdr == nil && data == nil && opts.Last {
+		// stream.CloseSend uses this to send an empty frame with endStream=True
+		t.controlBuf.put(&dataFrame{streamID: s.id, endStream: true, f: func() {}})
+		return nil
+	}
+	// Add data to header frame so that we can equally distribute data across frames.
+	emptyLen := http2MaxFrameLen - len(hdr)
+	if emptyLen > len(data) {
+		emptyLen = len(data)
+	}
+	hdr = append(hdr, data[:emptyLen]...)
+	data = data[emptyLen:]
+	for idx, r := range [][]byte{hdr, data} {
+		for len(r) > 0 {
 			size := http2MaxFrameLen
 			// Wait until the stream has some quota to send the data.
-			sq, err := wait(s.ctx, s.done, s.goAway, t.shutdownChan, s.sendQuotaPool.acquire())
+			quotaChan, quotaVer := s.sendQuotaPool.acquireWithVersion()
+			sq, err := wait(s.ctx, t.ctx, s.done, s.goAway, quotaChan)
 			if err != nil {
 				return err
 			}
 			// Wait until the transport has some quota to send the data.
-			tq, err := wait(s.ctx, s.done, s.goAway, t.shutdownChan, t.sendQuotaPool.acquire())
+			tq, err := wait(s.ctx, t.ctx, s.done, s.goAway, t.sendQuotaPool.acquire())
 			if err != nil {
 				return err
 			}
@@ -672,69 +679,51 @@ func (t *http2Client) Write(s *Stream, data []byte, opts *Options) error {
 			if tq < size {
 				size = tq
 			}
-			p = r.Next(size)
-			ps := len(p)
-			if ps < sq {
-				// Overbooked stream quota. Return it back.
-				s.sendQuotaPool.add(sq - ps)
+			if size > len(r) {
+				size = len(r)
 			}
+			p := r[:size]
+			ps := len(p)
 			if ps < tq {
 				// Overbooked transport quota. Return it back.
 				t.sendQuotaPool.add(tq - ps)
 			}
-		}
-		var (
-			endStream  bool
-			forceFlush bool
-		)
-		if opts.Last && r.Len() == 0 {
-			endStream = true
-		}
-		// Indicate there is a writer who is about to write a data frame.
-		t.framer.adjustNumWriters(1)
-		// Got some quota. Try to acquire writing privilege on the transport.
-		if _, err := wait(s.ctx, s.done, s.goAway, t.shutdownChan, t.writableChan); err != nil {
-			if _, ok := err.(StreamError); ok || err == io.EOF {
-				// Return the connection quota back.
-				t.sendQuotaPool.add(len(p))
+			// Acquire local send quota to be able to write to the controlBuf.
+			ltq, err := wait(s.ctx, t.ctx, s.done, s.goAway, s.localSendQuota.acquire())
+			if err != nil {
+				if _, ok := err.(ConnectionError); !ok {
+					t.sendQuotaPool.add(ps)
+				}
+				return err
 			}
-			if t.framer.adjustNumWriters(-1) == 0 {
-				// This writer is the last one in this batch and has the
-				// responsibility to flush the buffered frames. It queues
-				// a flush request to controlBuf instead of flushing directly
-				// in order to avoid the race with other writing or flushing.
-				t.controlBuf.put(&flushIO{})
+			s.localSendQuota.add(ltq - ps) // It's ok if we make it negative.
+			var endStream bool
+			// See if this is the last frame to be written.
+			if opts.Last {
+				if len(r)-size == 0 { // No more data in r after this iteration.
+					if idx == 0 { // We're writing data header.
+						if len(data) == 0 { // There's no data to follow.
+							endStream = true
+						}
+					} else { // We're writing data.
+						endStream = true
+					}
+				}
 			}
-			return err
-		}
-		select {
-		case <-s.ctx.Done():
-			t.sendQuotaPool.add(len(p))
-			if t.framer.adjustNumWriters(-1) == 0 {
-				t.controlBuf.put(&flushIO{})
+			success := func() {
+				t.controlBuf.put(&dataFrame{streamID: s.id, endStream: endStream, d: p, f: func() { s.localSendQuota.add(ps) }})
+				if ps < sq {
+					s.sendQuotaPool.lockedAdd(sq - ps)
+				}
+				r = r[ps:]
+			}
+			failure := func() {
+				s.sendQuotaPool.lockedAdd(sq)
+			}
+			if !s.sendQuotaPool.compareAndExecute(quotaVer, success, failure) {
+				t.sendQuotaPool.add(ps)
+				s.localSendQuota.add(ps)
 			}
-			t.writableChan <- 0
-			return ContextErr(s.ctx.Err())
-		default:
-		}
-		if r.Len() == 0 && t.framer.adjustNumWriters(0) == 1 {
-			// Do a force flush iff this is last frame for the entire gRPC message
-			// and the caller is the only writer at this moment.
-			forceFlush = true
-		}
-		// If WriteData fails, all the pending streams will be handled
-		// by http2Client.Close(). No explicit CloseStream() needs to be
-		// invoked.
-		if err := t.framer.writeData(forceFlush, s.id, endStream, p); err != nil {
-			t.notifyError(err)
-			return connectionErrorf(true, err, "transport: %v", err)
-		}
-		if t.framer.adjustNumWriters(-1) == 0 {
-			t.framer.flushWrite()
-		}
-		t.writableChan <- 0
-		if r.Len() == 0 {
-			break
 		}
 	}
 	if !opts.Last {
@@ -755,6 +744,24 @@ func (t *http2Client) getStream(f http2.Frame) (*Stream, bool) {
 	return s, ok
 }
 
+// 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) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.state == streamDone {
+		return
+	}
+	if w := s.fc.maybeAdjust(n); w > 0 {
+		// Piggyback connection's window update along.
+		if cw := t.fc.resetPendingUpdate(); cw > 0 {
+			t.controlBuf.put(&windowUpdate{0, cw})
+		}
+		t.controlBuf.put(&windowUpdate{s.id, w})
+	}
+}
+
 // updateWindow adjusts the inbound quota for the stream and the transport.
 // Window updates will deliver to the controller for sending when
 // the cumulative quota exceeds the corresponding threshold.
@@ -764,41 +771,76 @@ func (t *http2Client) updateWindow(s *Stream, n uint32) {
 	if s.state == streamDone {
 		return
 	}
-	if w := t.fc.onRead(n); w > 0 {
-		t.controlBuf.put(&windowUpdate{0, w})
-	}
 	if w := s.fc.onRead(n); w > 0 {
+		if cw := t.fc.resetPendingUpdate(); cw > 0 {
+			t.controlBuf.put(&windowUpdate{0, cw})
+		}
 		t.controlBuf.put(&windowUpdate{s.id, 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.initialWindowSize = int32(n)
+	t.mu.Unlock()
+	t.controlBuf.put(&windowUpdate{0, t.fc.newLimit(n)})
+	t.controlBuf.put(&settings{
+		ack: false,
+		ss: []http2.Setting{
+			{
+				ID:  http2.SettingInitialWindowSize,
+				Val: uint32(n),
+			},
+		},
+	})
+}
+
 func (t *http2Client) handleData(f *http2.DataFrame) {
 	size := f.Header().Length
-	if err := t.fc.onData(uint32(size)); err != nil {
-		t.notifyError(connectionErrorf(true, err, "%v", err))
-		return
+	var sendBDPPing bool
+	if t.bdpEst != nil {
+		sendBDPPing = t.bdpEst.add(uint32(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.
+	//
+	// Furthermore, if a bdpPing is being sent out we can piggyback
+	// connection's window update for the bytes we just received.
+	if sendBDPPing {
+		if size != 0 { // Could've been an empty data frame.
+			t.controlBuf.put(&windowUpdate{0, uint32(size)})
+		}
+		t.controlBuf.put(bdpPing)
+	} else {
+		if err := t.fc.onData(uint32(size)); err != nil {
+			t.Close()
+			return
+		}
+		if w := t.fc.onRead(uint32(size)); w > 0 {
+			t.controlBuf.put(&windowUpdate{0, w})
+		}
 	}
 	// Select the right stream to dispatch.
 	s, ok := t.getStream(f)
 	if !ok {
-		if w := t.fc.onRead(uint32(size)); w > 0 {
-			t.controlBuf.put(&windowUpdate{0, w})
-		}
 		return
 	}
 	if size > 0 {
-		if f.Header().Flags.Has(http2.FlagDataPadded) {
-			if w := t.fc.onRead(uint32(size) - uint32(len(f.Data()))); w > 0 {
-				t.controlBuf.put(&windowUpdate{0, w})
-			}
-		}
 		s.mu.Lock()
 		if s.state == streamDone {
 			s.mu.Unlock()
-			// The stream has been closed. Release the corresponding quota.
-			if w := t.fc.onRead(uint32(size)); w > 0 {
-				t.controlBuf.put(&windowUpdate{0, w})
-			}
 			return
 		}
 		if err := s.fc.onData(uint32(size)); err != nil {
@@ -854,10 +896,10 @@ func (t *http2Client) handleRSTStream(f *http2.RSTStreamFrame) {
 	}
 	statusCode, ok := http2ErrConvTab[http2.ErrCode(f.ErrCode)]
 	if !ok {
-		grpclog.Println("transport: http2Client.handleRSTStream found no mapped gRPC status for the received http2 error ", f.ErrCode)
+		warningf("transport: http2Client.handleRSTStream found no mapped gRPC status for the received http2 error %v", f.ErrCode)
 		statusCode = codes.Unknown
 	}
-	s.finish(status.Newf(statusCode, "stream terminated by RST_STREAM with error code: %d", f.ErrCode))
+	s.finish(status.Newf(statusCode, "stream terminated by RST_STREAM with error code: %v", f.ErrCode))
 	s.mu.Unlock()
 	s.write(recvMsg{err: io.EOF})
 }
@@ -876,7 +918,11 @@ func (t *http2Client) handleSettings(f *http2.SettingsFrame) {
 }
 
 func (t *http2Client) handlePing(f *http2.PingFrame) {
-	if f.IsAck() { // Do nothing.
+	if f.IsAck() {
+		// Maybe it's a BDP ping.
+		if t.bdpEst != nil {
+			t.bdpEst.calculate(f.Data)
+		}
 		return
 	}
 	pingAck := &ping{ack: true}
@@ -885,35 +931,76 @@ func (t *http2Client) handlePing(f *http2.PingFrame) {
 }
 
 func (t *http2Client) handleGoAway(f *http2.GoAwayFrame) {
+	t.mu.Lock()
+	if t.state != reachable && t.state != draining {
+		t.mu.Unlock()
+		return
+	}
 	if f.ErrCode == http2.ErrCodeEnhanceYourCalm {
-		grpclog.Printf("Client received GoAway with http2.ErrCodeEnhanceYourCalm.")
+		infof("Client received GoAway with http2.ErrCodeEnhanceYourCalm.")
 	}
-	t.mu.Lock()
-	if t.state == reachable || t.state == draining {
-		if f.LastStreamID > 0 && f.LastStreamID%2 != 1 {
-			t.mu.Unlock()
-			t.notifyError(connectionErrorf(true, nil, "received illegal http2 GOAWAY frame: stream ID %d is even", f.LastStreamID))
-			return
-		}
-		select {
-		case <-t.goAway:
-			id := t.goAwayID
-			// t.goAway has been closed (i.e.,multiple GoAways).
-			if id < f.LastStreamID {
-				t.mu.Unlock()
-				t.notifyError(connectionErrorf(true, nil, "received illegal http2 GOAWAY frame: previously recv GOAWAY frame with LastStramID %d, currently recv %d", id, f.LastStreamID))
-				return
-			}
-			t.prevGoAwayID = id
-			t.goAwayID = f.LastStreamID
+	id := f.LastStreamID
+	if id > 0 && id%2 != 1 {
+		t.mu.Unlock()
+		t.Close()
+		return
+	}
+	// A client can receive multiple GoAways from server (look at 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 really close any streams. While in case of second GoAway we
+	// close all streams created after the second 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.goAwayID = f.LastStreamID
+	default:
+		t.setGoAwayReason(f)
 		close(t.goAway)
+		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 {
+			close(stream.goAway)
+		}
+	}
+	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 = NoReason
+	switch f.ErrCode {
+	case http2.ErrCodeEnhanceYourCalm:
+		if string(f.DebugData()) == "too_many_pings" {
+			t.goAwayReason = TooManyPings
+		}
+	}
+}
+
+func (t *http2Client) GetGoAwayReason() GoAwayReason {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.goAwayReason
 }
 
 func (t *http2Client) handleWindowUpdate(f *http2.WindowUpdateFrame) {
@@ -934,19 +1021,20 @@ func (t *http2Client) operateHeaders(frame *http2.MetaHeadersFrame) {
 	if !ok {
 		return
 	}
+	s.mu.Lock()
+	s.bytesReceived = true
+	s.mu.Unlock()
 	var state decodeState
-	for _, hf := range frame.Fields {
-		if err := state.processHeaderField(hf); err != nil {
-			s.mu.Lock()
-			if !s.headerDone {
-				close(s.headerChan)
-				s.headerDone = true
-			}
-			s.mu.Unlock()
-			s.write(recvMsg{err: err})
-			// Something wrong. Stops reading even when there is remaining.
-			return
+	if err := state.decodeResponseHeader(frame); err != nil {
+		s.mu.Lock()
+		if !s.headerDone {
+			close(s.headerChan)
+			s.headerDone = true
 		}
+		s.mu.Unlock()
+		s.write(recvMsg{err: err})
+		// Something wrong. Stops reading even when there is remaining.
+		return
 	}
 
 	endStream := frame.StreamEnded()
@@ -958,13 +1046,13 @@ func (t *http2Client) operateHeaders(frame *http2.MetaHeadersFrame) {
 					Client:     true,
 					WireLength: int(frame.Header().Length),
 				}
-				t.statsHandler.HandleRPC(s.clientStatsCtx, inHeader)
+				t.statsHandler.HandleRPC(s.ctx, inHeader)
 			} else {
 				inTrailer := &stats.InTrailer{
 					Client:     true,
 					WireLength: int(frame.Header().Length),
 				}
-				t.statsHandler.HandleRPC(s.clientStatsCtx, inTrailer)
+				t.statsHandler.HandleRPC(s.ctx, inTrailer)
 			}
 		}
 	}()
@@ -1012,22 +1100,22 @@ func handleMalformedHTTP2(s *Stream, err error) {
 // TODO(zhaoq): Check the validity of the incoming frame sequence.
 func (t *http2Client) reader() {
 	// Check the validity of server preface.
-	frame, err := t.framer.readFrame()
+	frame, err := t.framer.fr.ReadFrame()
 	if err != nil {
-		t.notifyError(err)
+		t.Close()
 		return
 	}
 	atomic.CompareAndSwapUint32(&t.activity, 0, 1)
 	sf, ok := frame.(*http2.SettingsFrame)
 	if !ok {
-		t.notifyError(err)
+		t.Close()
 		return
 	}
 	t.handleSettings(sf)
 
 	// loop to keep reading incoming messages on this transport.
 	for {
-		frame, err := t.framer.readFrame()
+		frame, err := t.framer.fr.ReadFrame()
 		atomic.CompareAndSwapUint32(&t.activity, 0, 1)
 		if err != nil {
 			// Abort an active stream if the http2.Framer returns a
@@ -1039,12 +1127,12 @@ func (t *http2Client) reader() {
 				t.mu.Unlock()
 				if s != nil {
 					// use error detail to provide better err message
-					handleMalformedHTTP2(s, streamErrorf(http2ErrConvTab[se.Code], "%v", t.framer.errorDetail()))
+					handleMalformedHTTP2(s, streamErrorf(http2ErrConvTab[se.Code], "%v", t.framer.fr.ErrorDetail()))
 				}
 				continue
 			} else {
 				// Transport error.
-				t.notifyError(err)
+				t.Close()
 				return
 			}
 		}
@@ -1064,7 +1152,7 @@ func (t *http2Client) reader() {
 		case *http2.WindowUpdateFrame:
 			t.handleWindowUpdate(frame)
 		default:
-			grpclog.Printf("transport: http2Client.reader got unhandled frame type %v.", frame)
+			errorf("transport: http2Client.reader got unhandled frame type %v.", frame)
 		}
 	}
 }
@@ -1088,7 +1176,7 @@ func (t *http2Client) applySettings(ss []http2.Setting) {
 			t.mu.Lock()
 			for _, stream := range t.activeStreams {
 				// Adjust the sending quota for each stream.
-				stream.sendQuotaPool.add(int(s.Val - t.streamSendQuota))
+				stream.sendQuotaPool.addAndUpdate(int(s.Val) - int(t.streamSendQuota))
 			}
 			t.streamSendQuota = s.Val
 			t.mu.Unlock()
@@ -1096,49 +1184,78 @@ func (t *http2Client) applySettings(ss []http2.Setting) {
 	}
 }
 
-// controller running in a separate goroutine takes charge of sending control
-// frames (e.g., window update, reset stream, setting, etc.) to the server.
-func (t *http2Client) controller() {
-	for {
-		select {
-		case i := <-t.controlBuf.get():
-			t.controlBuf.load()
-			select {
-			case <-t.writableChan:
-				switch i := i.(type) {
-				case *windowUpdate:
-					t.framer.writeWindowUpdate(true, i.streamID, i.increment)
-				case *settings:
-					if i.ack {
-						t.framer.writeSettingsAck(true)
-						t.applySettings(i.ss)
-					} else {
-						t.framer.writeSettings(true, i.ss...)
-					}
-				case *resetStream:
-					// If the server needs to be to intimated about stream closing,
-					// then we need to make sure the RST_STREAM frame is written to
-					// the wire before the headers of the next stream waiting on
-					// streamQuota. We ensure this by adding to the streamsQuota pool
-					// only after having acquired the writableChan to send RST_STREAM.
-					t.streamsQuota.add(1)
-					t.framer.writeRSTStream(true, i.streamID, i.code)
-				case *flushIO:
-					t.framer.flushWrite()
-				case *ping:
-					t.framer.writePing(true, i.ack, i.data)
-				default:
-					grpclog.Printf("transport: http2Client.controller got unexpected item type %v\n", i)
-				}
-				t.writableChan <- 0
-				continue
-			case <-t.shutdownChan:
-				return
+// TODO(mmukhi): A lot of this code(and code in other places in the tranpsort layer)
+// is duplicated between the client and the server.
+// The transport layer needs to be refactored to take care of this.
+func (t *http2Client) itemHandler(i item) error {
+	var err error
+	switch i := i.(type) {
+	case *dataFrame:
+		err = t.framer.fr.WriteData(i.streamID, i.endStream, i.d)
+		if err == nil {
+			i.f()
+		}
+	case *headerFrame:
+		t.hBuf.Reset()
+		for _, f := range i.hf {
+			t.hEnc.WriteField(f)
+		}
+		endHeaders := false
+		first := true
+		for !endHeaders {
+			size := t.hBuf.Len()
+			if size > http2MaxFrameLen {
+				size = http2MaxFrameLen
+			} else {
+				endHeaders = true
 			}
-		case <-t.shutdownChan:
-			return
+			if first {
+				first = false
+				err = t.framer.fr.WriteHeaders(http2.HeadersFrameParam{
+					StreamID:      i.streamID,
+					BlockFragment: t.hBuf.Next(size),
+					EndStream:     i.endStream,
+					EndHeaders:    endHeaders,
+				})
+			} else {
+				err = t.framer.fr.WriteContinuation(
+					i.streamID,
+					endHeaders,
+					t.hBuf.Next(size),
+				)
+			}
+			if err != nil {
+				return err
+			}
+		}
+	case *windowUpdate:
+		err = t.framer.fr.WriteWindowUpdate(i.streamID, i.increment)
+	case *settings:
+		if i.ack {
+			t.applySettings(i.ss)
+			err = t.framer.fr.WriteSettingsAck()
+		} else {
+			err = t.framer.fr.WriteSettings(i.ss...)
+		}
+	case *resetStream:
+		// If the server needs to be to intimated about stream closing,
+		// then we need to make sure the RST_STREAM frame is written to
+		// the wire before the headers of the next stream waiting on
+		// streamQuota. We ensure this by adding to the streamsQuota pool
+		// only after having acquired the writableChan to send RST_STREAM.
+		err = t.framer.fr.WriteRSTStream(i.streamID, i.code)
+		t.streamsQuota.add(1)
+	case *flushIO:
+		err = t.framer.writer.Flush()
+	case *ping:
+		if !i.ack {
+			t.bdpEst.timesnap(i.data)
 		}
+		err = t.framer.fr.WritePing(i.ack, i.data)
+	default:
+		errorf("transport: http2Client.controller got unexpected item type %v", i)
 	}
+	return err
 }
 
 // keepalive running in a separate goroutune makes sure the connection is alive by sending pings.
@@ -1162,7 +1279,7 @@ func (t *http2Client) keepalive() {
 				case <-t.awakenKeepalive:
 					// If the control gets here a ping has been sent
 					// need to reset the timer with keepalive.Timeout.
-				case <-t.shutdownChan:
+				case <-t.ctx.Done():
 					return
 				}
 			} else {
@@ -1181,13 +1298,13 @@ func (t *http2Client) keepalive() {
 				}
 				t.Close()
 				return
-			case <-t.shutdownChan:
+			case <-t.ctx.Done():
 				if !timer.Stop() {
 					<-timer.C
 				}
 				return
 			}
-		case <-t.shutdownChan:
+		case <-t.ctx.Done():
 			if !timer.Stop() {
 				<-timer.C
 			}
@@ -1197,25 +1314,9 @@ func (t *http2Client) keepalive() {
 }
 
 func (t *http2Client) Error() <-chan struct{} {
-	return t.errorChan
+	return t.ctx.Done()
 }
 
 func (t *http2Client) GoAway() <-chan struct{} {
 	return t.goAway
 }
-
-func (t *http2Client) notifyError(err error) {
-	t.mu.Lock()
-	// make sure t.errorChan is closed only once.
-	if t.state == draining {
-		t.mu.Unlock()
-		t.Close()
-		return
-	}
-	if t.state == reachable {
-		t.state = unreachable
-		close(t.errorChan)
-		grpclog.Printf("transport: http2Client.notifyError got notified that the client transport was broken %v.", err)
-	}
-	t.mu.Unlock()
-}
diff --git a/vendor/google.golang.org/grpc/transport/http2_server.go b/vendor/google.golang.org/grpc/transport/http2_server.go
index 31fefc7..bad29b8 100644
--- a/vendor/google.golang.org/grpc/transport/http2_server.go
+++ b/vendor/google.golang.org/grpc/transport/http2_server.go
@@ -1,33 +1,18 @@
 /*
  *
- * Copyright 2014, Google Inc.
- * All rights reserved.
+ * Copyright 2014 gRPC authors.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
+ * 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
  *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 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.
  *
  */
 
@@ -36,6 +21,7 @@ package transport
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"math"
 	"math/rand"
@@ -51,7 +37,6 @@ import (
 	"golang.org/x/net/http2/hpack"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials"
-	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
@@ -67,35 +52,25 @@ var ErrIllegalHeaderWrite = errors.New("transport: the stream is done or WriteHe
 // http2Server implements the ServerTransport interface with HTTP2.
 type http2Server struct {
 	ctx         context.Context
+	cancel      context.CancelFunc
 	conn        net.Conn
 	remoteAddr  net.Addr
 	localAddr   net.Addr
 	maxStreamID uint32               // max stream ID ever seen
 	authInfo    credentials.AuthInfo // auth info about the connection
 	inTapHandle tap.ServerInHandle
-	// writableChan synchronizes write access to the transport.
-	// A writer acquires the write lock by receiving a value on writableChan
-	// and releases it by sending on writableChan.
-	writableChan chan int
-	// shutdownChan is closed when Close is called.
-	// Blocking operations should select on shutdownChan to avoid
-	// blocking forever after Close.
-	shutdownChan chan struct{}
-	framer       *framer
-	hBuf         *bytes.Buffer  // the buffer for HPACK encoding
-	hEnc         *hpack.Encoder // HPACK encoder
-
+	framer      *framer
+	hBuf        *bytes.Buffer  // the buffer for HPACK encoding
+	hEnc        *hpack.Encoder // HPACK encoder
 	// The max number of concurrent streams.
 	maxStreams uint32
 	// controlBuf delivers all the control related tasks (e.g., window
 	// updates, reset streams, and various settings) to the controller.
-	controlBuf *recvBuffer
+	controlBuf *controlBuffer
 	fc         *inFlow
 	// sendQuotaPool provides flow control to outbound message.
 	sendQuotaPool *quotaPool
-
-	stats stats.Handler
-
+	stats         stats.Handler
 	// Flag to keep track of reading activity on transport.
 	// 1 is true and 0 is false.
 	activity uint32 // Accessed atomically.
@@ -111,15 +86,25 @@ type http2Server struct {
 	// Flag to signify that number of ping strikes should be reset to 0.
 	// This is set whenever data or header frames are sent.
 	// 1 means yes.
-	resetPingStrikes uint32 // Accessed atomically.
+	resetPingStrikes  uint32 // Accessed atomically.
+	initialWindowSize int32
+	bdpEst            *bdpEstimator
+
+	mu sync.Mutex // guard the following
 
-	mu            sync.Mutex // guard the following
+	// drainChan is initialized when drain(...) is called the first time.
+	// After which the server writes out the first GoAway(with ID 2^31-1) frame.
+	// Then an independent goroutine will be launched to later send the second GoAway.
+	// During this time we don't want to write another first GoAway(with ID 2^31 -1) frame.
+	// Thus call to drain(...) will be a no-op if drainChan is already initialized since draining is
+	// already underway.
+	drainChan     chan struct{}
 	state         transportState
 	activeStreams map[uint32]*Stream
 	// the per-stream outbound flow control window size set by the peer.
 	streamSendQuota uint32
 	// idle is the time instant when the connection went idle.
-	// This is either the begining of the connection or when the number of
+	// This is either the beginning of the connection or when the number of
 	// RPCs go down to 0.
 	// When the connection is busy, this value is set to 0.
 	idle time.Time
@@ -128,31 +113,50 @@ type http2Server struct {
 // newHTTP2Server constructs a ServerTransport based on HTTP2. ConnectionError is
 // returned if something goes wrong.
 func newHTTP2Server(conn net.Conn, config *ServerConfig) (_ ServerTransport, err error) {
-	framer := newFramer(conn)
+	writeBufSize := defaultWriteBufSize
+	if config.WriteBufferSize > 0 {
+		writeBufSize = config.WriteBufferSize
+	}
+	readBufSize := defaultReadBufSize
+	if config.ReadBufferSize > 0 {
+		readBufSize = config.ReadBufferSize
+	}
+	framer := newFramer(conn, writeBufSize, readBufSize)
 	// Send initial settings as connection preface to client.
-	var settings []http2.Setting
+	var isettings []http2.Setting
 	// TODO(zhaoq): Have a better way to signal "no limit" because 0 is
 	// permitted in the HTTP2 spec.
 	maxStreams := config.MaxStreams
 	if maxStreams == 0 {
 		maxStreams = math.MaxUint32
 	} else {
-		settings = append(settings, http2.Setting{
+		isettings = append(isettings, http2.Setting{
 			ID:  http2.SettingMaxConcurrentStreams,
 			Val: maxStreams,
 		})
 	}
-	if initialWindowSize != defaultWindowSize {
-		settings = append(settings, http2.Setting{
+	dynamicWindow := true
+	iwz := int32(initialWindowSize)
+	if config.InitialWindowSize >= defaultWindowSize {
+		iwz = config.InitialWindowSize
+		dynamicWindow = false
+	}
+	icwz := int32(initialWindowSize)
+	if config.InitialConnWindowSize >= defaultWindowSize {
+		icwz = config.InitialConnWindowSize
+		dynamicWindow = false
+	}
+	if iwz != defaultWindowSize {
+		isettings = append(isettings, http2.Setting{
 			ID:  http2.SettingInitialWindowSize,
-			Val: uint32(initialWindowSize)})
+			Val: uint32(iwz)})
 	}
-	if err := framer.writeSettings(true, settings...); err != nil {
+	if err := framer.fr.WriteSettings(isettings...); err != nil {
 		return nil, connectionErrorf(true, err, "transport: %v", err)
 	}
 	// Adjust the connection flow control window if needed.
-	if delta := uint32(initialConnWindowSize - defaultWindowSize); delta > 0 {
-		if err := framer.writeWindowUpdate(true, 0, delta); err != nil {
+	if delta := uint32(icwz - defaultWindowSize); delta > 0 {
+		if err := framer.fr.WriteWindowUpdate(0, delta); err != nil {
 			return nil, connectionErrorf(true, err, "transport: %v", err)
 		}
 	}
@@ -179,29 +183,36 @@ func newHTTP2Server(conn net.Conn, config *ServerConfig) (_ ServerTransport, err
 		kep.MinTime = defaultKeepalivePolicyMinTime
 	}
 	var buf bytes.Buffer
+	ctx, cancel := context.WithCancel(context.Background())
 	t := &http2Server{
-		ctx:             context.Background(),
-		conn:            conn,
-		remoteAddr:      conn.RemoteAddr(),
-		localAddr:       conn.LocalAddr(),
-		authInfo:        config.AuthInfo,
-		framer:          framer,
-		hBuf:            &buf,
-		hEnc:            hpack.NewEncoder(&buf),
-		maxStreams:      maxStreams,
-		inTapHandle:     config.InTapHandle,
-		controlBuf:      newRecvBuffer(),
-		fc:              &inFlow{limit: initialConnWindowSize},
-		sendQuotaPool:   newQuotaPool(defaultWindowSize),
-		state:           reachable,
-		writableChan:    make(chan int, 1),
-		shutdownChan:    make(chan struct{}),
-		activeStreams:   make(map[uint32]*Stream),
-		streamSendQuota: defaultWindowSize,
-		stats:           config.StatsHandler,
-		kp:              kp,
-		idle:            time.Now(),
-		kep:             kep,
+		ctx:               ctx,
+		cancel:            cancel,
+		conn:              conn,
+		remoteAddr:        conn.RemoteAddr(),
+		localAddr:         conn.LocalAddr(),
+		authInfo:          config.AuthInfo,
+		framer:            framer,
+		hBuf:              &buf,
+		hEnc:              hpack.NewEncoder(&buf),
+		maxStreams:        maxStreams,
+		inTapHandle:       config.InTapHandle,
+		controlBuf:        newControlBuffer(),
+		fc:                &inFlow{limit: uint32(icwz)},
+		sendQuotaPool:     newQuotaPool(defaultWindowSize),
+		state:             reachable,
+		activeStreams:     make(map[uint32]*Stream),
+		streamSendQuota:   defaultWindowSize,
+		stats:             config.StatsHandler,
+		kp:                kp,
+		idle:              time.Now(),
+		kep:               kep,
+		initialWindowSize: iwz,
+	}
+	if dynamicWindow {
+		t.bdpEst = &bdpEstimator{
+			bdp:               initialWindowSize,
+			updateFlowControl: t.updateFlowControl,
+		}
 	}
 	if t.stats != nil {
 		t.ctx = t.stats.TagConn(t.ctx, &stats.ConnTagInfo{
@@ -211,37 +222,43 @@ func newHTTP2Server(conn net.Conn, config *ServerConfig) (_ ServerTransport, err
 		connBegin := &stats.ConnBegin{}
 		t.stats.HandleConn(t.ctx, connBegin)
 	}
-	go t.controller()
+	t.framer.writer.Flush()
+	go func() {
+		loopyWriter(t.ctx, t.controlBuf, t.itemHandler)
+		t.Close()
+	}()
 	go t.keepalive()
-	t.writableChan <- 0
 	return t, nil
 }
 
 // operateHeader takes action on the decoded headers.
 func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(*Stream), traceCtx func(context.Context, string) context.Context) (close bool) {
-	buf := newRecvBuffer()
-	s := &Stream{
-		id:  frame.Header().StreamID,
-		st:  t,
-		buf: buf,
-		fc:  &inFlow{limit: initialWindowSize},
-	}
+	streamID := frame.Header().StreamID
 
 	var state decodeState
 	for _, hf := range frame.Fields {
 		if err := state.processHeaderField(hf); err != nil {
 			if se, ok := err.(StreamError); ok {
-				t.controlBuf.put(&resetStream{s.id, statusCodeConvTab[se.Code]})
+				t.controlBuf.put(&resetStream{streamID, statusCodeConvTab[se.Code]})
 			}
 			return
 		}
 	}
 
+	buf := newRecvBuffer()
+	s := &Stream{
+		id:           streamID,
+		st:           t,
+		buf:          buf,
+		fc:           &inFlow{limit: uint32(t.initialWindowSize)},
+		recvCompress: state.encoding,
+		method:       state.method,
+	}
+
 	if frame.StreamEnded() {
 		// s is just created by the caller. No lock needed.
 		s.state = streamReadDone
 	}
-	s.recvCompress = state.encoding
 	if state.timeoutSet {
 		s.ctx, s.cancel = context.WithTimeout(t.ctx, state.timeout)
 	} else {
@@ -263,13 +280,12 @@ func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(
 	if len(state.mdata) > 0 {
 		s.ctx = metadata.NewIncomingContext(s.ctx, state.mdata)
 	}
-
-	s.dec = &recvBufferReader{
-		ctx:  s.ctx,
-		recv: s.buf,
+	if state.statsTags != nil {
+		s.ctx = stats.SetIncomingTags(s.ctx, state.statsTags)
+	}
+	if state.statsTrace != nil {
+		s.ctx = stats.SetIncomingTrace(s.ctx, state.statsTrace)
 	}
-	s.recvCompress = state.encoding
-	s.method = state.method
 	if t.inTapHandle != nil {
 		var err error
 		info := &tap.Info{
@@ -277,7 +293,7 @@ func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(
 		}
 		s.ctx, err = t.inTapHandle(s.ctx, info)
 		if err != nil {
-			// TODO: Log the real error.
+			warningf("transport: http2Server.operateHeaders got an error from InTapHandle: %v", err)
 			t.controlBuf.put(&resetStream{s.id, http2.ErrCodeRefusedStream})
 			return
 		}
@@ -289,24 +305,25 @@ func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(
 	}
 	if uint32(len(t.activeStreams)) >= t.maxStreams {
 		t.mu.Unlock()
-		t.controlBuf.put(&resetStream{s.id, http2.ErrCodeRefusedStream})
+		t.controlBuf.put(&resetStream{streamID, http2.ErrCodeRefusedStream})
 		return
 	}
-	if s.id%2 != 1 || s.id <= t.maxStreamID {
+	if streamID%2 != 1 || streamID <= t.maxStreamID {
 		t.mu.Unlock()
 		// illegal gRPC stream id.
-		grpclog.Println("transport: http2Server.HandleStreams received an illegal stream id: ", s.id)
+		errorf("transport: http2Server.HandleStreams received an illegal stream id: %v", streamID)
 		return true
 	}
-	t.maxStreamID = s.id
+	t.maxStreamID = streamID
 	s.sendQuotaPool = newQuotaPool(int(t.streamSendQuota))
-	t.activeStreams[s.id] = s
+	s.localSendQuota = newQuotaPool(defaultLocalSendQuota)
+	t.activeStreams[streamID] = s
 	if len(t.activeStreams) == 1 {
 		t.idle = time.Time{}
 	}
 	t.mu.Unlock()
-	s.windowHandler = func(n int) {
-		t.updateWindow(s, uint32(n))
+	s.requestRead = func(n int) {
+		t.adjustWindow(s, uint32(n))
 	}
 	s.ctx = traceCtx(s.ctx, s.method)
 	if t.stats != nil {
@@ -320,6 +337,15 @@ func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(
 		}
 		t.stats.HandleRPC(s.ctx, inHeader)
 	}
+	s.trReader = &transportReader{
+		reader: &recvBufferReader{
+			ctx:  s.ctx,
+			recv: s.buf,
+		},
+		windowHandler: func(n int) {
+			t.updateWindow(s, uint32(n))
+		},
+	}
 	handle(s)
 	return
 }
@@ -331,37 +357,40 @@ func (t *http2Server) HandleStreams(handle func(*Stream), traceCtx func(context.
 	// Check the validity of client preface.
 	preface := make([]byte, len(clientPreface))
 	if _, err := io.ReadFull(t.conn, preface); err != nil {
-		grpclog.Printf("transport: http2Server.HandleStreams failed to receive the preface from client: %v", err)
+		// Only log if it isn't a simple tcp accept check (ie: tcp balancer doing open/close socket)
+		if err != io.EOF {
+			errorf("transport: http2Server.HandleStreams failed to receive the preface from client: %v", err)
+		}
 		t.Close()
 		return
 	}
 	if !bytes.Equal(preface, clientPreface) {
-		grpclog.Printf("transport: http2Server.HandleStreams received bogus greeting from client: %q", preface)
+		errorf("transport: http2Server.HandleStreams received bogus greeting from client: %q", preface)
 		t.Close()
 		return
 	}
 
-	frame, err := t.framer.readFrame()
+	frame, err := t.framer.fr.ReadFrame()
 	if err == io.EOF || err == io.ErrUnexpectedEOF {
 		t.Close()
 		return
 	}
 	if err != nil {
-		grpclog.Printf("transport: http2Server.HandleStreams failed to read frame: %v", err)
+		errorf("transport: http2Server.HandleStreams failed to read initial settings frame: %v", err)
 		t.Close()
 		return
 	}
 	atomic.StoreUint32(&t.activity, 1)
 	sf, ok := frame.(*http2.SettingsFrame)
 	if !ok {
-		grpclog.Printf("transport: http2Server.HandleStreams saw invalid preface type %T from client", frame)
+		errorf("transport: http2Server.HandleStreams saw invalid preface type %T from client", frame)
 		t.Close()
 		return
 	}
 	t.handleSettings(sf)
 
 	for {
-		frame, err := t.framer.readFrame()
+		frame, err := t.framer.fr.ReadFrame()
 		atomic.StoreUint32(&t.activity, 1)
 		if err != nil {
 			if se, ok := err.(http2.StreamError); ok {
@@ -378,7 +407,7 @@ func (t *http2Server) HandleStreams(handle func(*Stream), traceCtx func(context.
 				t.Close()
 				return
 			}
-			grpclog.Printf("transport: http2Server.HandleStreams failed to read frame: %v", err)
+			warningf("transport: http2Server.HandleStreams failed to read frame: %v", err)
 			t.Close()
 			return
 		}
@@ -401,7 +430,7 @@ func (t *http2Server) HandleStreams(handle func(*Stream), traceCtx func(context.
 		case *http2.GoAwayFrame:
 			// TODO: Handle GoAway from the client appropriately.
 		default:
-			grpclog.Printf("transport: http2Server.HandleStreams found unhandled frame type %v.", frame)
+			errorf("transport: http2Server.HandleStreams found unhandled frame type %v.", frame)
 		}
 	}
 }
@@ -421,6 +450,23 @@ func (t *http2Server) getStream(f http2.Frame) (*Stream, bool) {
 	return s, true
 }
 
+// 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 *http2Server) adjustWindow(s *Stream, n uint32) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.state == streamDone {
+		return
+	}
+	if w := s.fc.maybeAdjust(n); w > 0 {
+		if cw := t.fc.resetPendingUpdate(); cw > 0 {
+			t.controlBuf.put(&windowUpdate{0, cw})
+		}
+		t.controlBuf.put(&windowUpdate{s.id, w})
+	}
+}
+
 // updateWindow adjusts the inbound quota for the stream and the transport.
 // Window updates will deliver to the controller for sending when
 // the cumulative quota exceeds the corresponding threshold.
@@ -430,42 +476,78 @@ func (t *http2Server) updateWindow(s *Stream, n uint32) {
 	if s.state == streamDone {
 		return
 	}
-	if w := t.fc.onRead(n); w > 0 {
-		t.controlBuf.put(&windowUpdate{0, w})
-	}
 	if w := s.fc.onRead(n); w > 0 {
+		if cw := t.fc.resetPendingUpdate(); cw > 0 {
+			t.controlBuf.put(&windowUpdate{0, cw})
+		}
 		t.controlBuf.put(&windowUpdate{s.id, w})
 	}
 }
 
+// updateFlowControl updates the incoming flow control windows
+// for the transport and the stream based on the current bdp
+// estimation.
+func (t *http2Server) updateFlowControl(n uint32) {
+	t.mu.Lock()
+	for _, s := range t.activeStreams {
+		s.fc.newLimit(n)
+	}
+	t.initialWindowSize = int32(n)
+	t.mu.Unlock()
+	t.controlBuf.put(&windowUpdate{0, t.fc.newLimit(n)})
+	t.controlBuf.put(&settings{
+		ack: false,
+		ss: []http2.Setting{
+			{
+				ID:  http2.SettingInitialWindowSize,
+				Val: uint32(n),
+			},
+		},
+	})
+
+}
+
 func (t *http2Server) handleData(f *http2.DataFrame) {
 	size := f.Header().Length
-	if err := t.fc.onData(uint32(size)); err != nil {
-		grpclog.Printf("transport: http2Server %v", err)
-		t.Close()
-		return
+	var sendBDPPing bool
+	if t.bdpEst != nil {
+		sendBDPPing = t.bdpEst.add(uint32(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.
+	//
+	// Furthermore, if a bdpPing is being sent out we can piggyback
+	// connection's window update for the bytes we just received.
+	if sendBDPPing {
+		if size != 0 { // Could be an empty frame.
+			t.controlBuf.put(&windowUpdate{0, uint32(size)})
+		}
+		t.controlBuf.put(bdpPing)
+	} else {
+		if err := t.fc.onData(uint32(size)); err != nil {
+			errorf("transport: http2Server %v", err)
+			t.Close()
+			return
+		}
+		if w := t.fc.onRead(uint32(size)); w > 0 {
+			t.controlBuf.put(&windowUpdate{0, w})
+		}
 	}
 	// Select the right stream to dispatch.
 	s, ok := t.getStream(f)
 	if !ok {
-		if w := t.fc.onRead(uint32(size)); w > 0 {
-			t.controlBuf.put(&windowUpdate{0, w})
-		}
 		return
 	}
 	if size > 0 {
-		if f.Header().Flags.Has(http2.FlagDataPadded) {
-			if w := t.fc.onRead(uint32(size) - uint32(len(f.Data()))); w > 0 {
-				t.controlBuf.put(&windowUpdate{0, w})
-			}
-		}
 		s.mu.Lock()
 		if s.state == streamDone {
 			s.mu.Unlock()
-			// The stream has been closed. Release the corresponding quota.
-			if w := t.fc.onRead(uint32(size)); w > 0 {
-				t.controlBuf.put(&windowUpdate{0, w})
-			}
 			return
 		}
 		if err := s.fc.onData(uint32(size)); err != nil {
@@ -517,17 +599,38 @@ func (t *http2Server) handleSettings(f *http2.SettingsFrame) {
 		ss = append(ss, s)
 		return nil
 	})
-	// The settings will be applied once the ack is sent.
 	t.controlBuf.put(&settings{ack: true, ss: ss})
 }
 
+func (t *http2Server) applySettings(ss []http2.Setting) {
+	for _, s := range ss {
+		if s.ID == http2.SettingInitialWindowSize {
+			t.mu.Lock()
+			for _, stream := range t.activeStreams {
+				stream.sendQuotaPool.addAndUpdate(int(s.Val) - int(t.streamSendQuota))
+			}
+			t.streamSendQuota = s.Val
+			t.mu.Unlock()
+		}
+
+	}
+}
+
 const (
 	maxPingStrikes     = 2
 	defaultPingTimeout = 2 * time.Hour
 )
 
 func (t *http2Server) handlePing(f *http2.PingFrame) {
-	if f.IsAck() { // Do nothing.
+	if f.IsAck() {
+		if f.Data == goAwayPing.data && t.drainChan != nil {
+			close(t.drainChan)
+			return
+		}
+		// Maybe it's a BDP ping.
+		if t.bdpEst != nil {
+			t.bdpEst.calculate(f.Data)
+		}
 		return
 	}
 	pingAck := &ping{ack: true}
@@ -550,7 +653,7 @@ func (t *http2Server) handlePing(f *http2.PingFrame) {
 	t.mu.Unlock()
 	if ns < 1 && !t.kep.PermitWithoutStream {
 		// Keepalive shouldn't be active thus, this new ping should
-		// have come after atleast defaultPingTimeout.
+		// have come after at least defaultPingTimeout.
 		if t.lastPingAt.Add(defaultPingTimeout).After(now) {
 			t.pingStrikes++
 		}
@@ -563,7 +666,8 @@ func (t *http2Server) handlePing(f *http2.PingFrame) {
 
 	if t.pingStrikes > maxPingStrikes {
 		// Send goaway and close the connection.
-		t.controlBuf.put(&goAway{code: http2.ErrCodeEnhanceYourCalm, debugData: []byte("too_many_pings")})
+		errorf("transport: Got to too many pings from the client, closing the connection.")
+		t.controlBuf.put(&goAway{code: http2.ErrCodeEnhanceYourCalm, debugData: []byte("too_many_pings"), closeConn: true})
 	}
 }
 
@@ -579,47 +683,16 @@ func (t *http2Server) handleWindowUpdate(f *http2.WindowUpdateFrame) {
 	}
 }
 
-func (t *http2Server) writeHeaders(s *Stream, b *bytes.Buffer, endStream bool) error {
-	first := true
-	endHeaders := false
-	var err error
-	defer func() {
-		if err == nil {
-			// Reset ping strikes when seding headers since that might cause the
-			// peer to send ping.
-			atomic.StoreUint32(&t.resetPingStrikes, 1)
-		}
-	}()
-	// Sends the headers in a single batch.
-	for !endHeaders {
-		size := t.hBuf.Len()
-		if size > http2MaxFrameLen {
-			size = http2MaxFrameLen
-		} else {
-			endHeaders = true
-		}
-		if first {
-			p := http2.HeadersFrameParam{
-				StreamID:      s.id,
-				BlockFragment: b.Next(size),
-				EndStream:     endStream,
-				EndHeaders:    endHeaders,
-			}
-			err = t.framer.writeHeaders(endHeaders, p)
-			first = false
-		} else {
-			err = t.framer.writeContinuation(endHeaders, s.id, endHeaders, b.Next(size))
-		}
-		if err != nil {
-			t.Close()
-			return connectionErrorf(true, err, "transport: %v", err)
-		}
-	}
-	return nil
-}
-
 // WriteHeader sends the header metedata md back to the client.
 func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
+	select {
+	case <-s.ctx.Done():
+		return ContextErr(s.ctx.Err())
+	case <-t.ctx.Done():
+		return ErrConnClosing
+	default:
+	}
+
 	s.mu.Lock()
 	if s.headerOk || s.state == streamDone {
 		s.mu.Unlock()
@@ -635,35 +708,34 @@ func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
 	}
 	md = s.header
 	s.mu.Unlock()
-	if _, err := wait(s.ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
-		return err
-	}
-	t.hBuf.Reset()
-	t.hEnc.WriteField(hpack.HeaderField{Name: ":status", Value: "200"})
-	t.hEnc.WriteField(hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
+	// TODO(mmukhi): Benchmark if the perfomance gets better if count the metadata and other header fields
+	// first and create a slice of that exact size.
+	headerFields := make([]hpack.HeaderField, 0, 2) // at least :status, content-type will be there if none else.
+	headerFields = append(headerFields, hpack.HeaderField{Name: ":status", Value: "200"})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
 	if s.sendCompress != "" {
-		t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-encoding", Value: s.sendCompress})
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-encoding", Value: s.sendCompress})
 	}
-	for k, v := range md {
+	for k, vv := range md {
 		if isReservedHeader(k) {
 			// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
 			continue
 		}
-		for _, entry := range v {
-			t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
+		for _, v := range vv {
+			headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
 		}
 	}
-	bufLen := t.hBuf.Len()
-	if err := t.writeHeaders(s, t.hBuf, false); err != nil {
-		return err
-	}
+	t.controlBuf.put(&headerFrame{
+		streamID:  s.id,
+		hf:        headerFields,
+		endStream: false,
+	})
 	if t.stats != nil {
 		outHeader := &stats.OutHeader{
-			WireLength: bufLen,
+		//WireLength: // TODO(mmukhi): Revisit this later, if needed.
 		}
 		t.stats.HandleRPC(s.Context(), outHeader)
 	}
-	t.writableChan <- 0
 	return nil
 }
 
@@ -672,6 +744,12 @@ func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
 // TODO(zhaoq): Now it indicates the end of entire stream. Revisit if early
 // OK is adopted.
 func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
+	select {
+	case <-t.ctx.Done():
+		return ErrConnClosing
+	default:
+	}
+
 	var headersSent, hasHeader bool
 	s.mu.Lock()
 	if s.state == streamDone {
@@ -691,20 +769,15 @@ func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
 		headersSent = true
 	}
 
-	if _, err := wait(s.ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
-		return err
-	}
-	t.hBuf.Reset()
+	// TODO(mmukhi): Benchmark if the perfomance gets better if count the metadata and other header fields
+	// first and create a slice of that exact size.
+	headerFields := make([]hpack.HeaderField, 0, 2) // grpc-status and grpc-message will be there if none else.
 	if !headersSent {
-		t.hEnc.WriteField(hpack.HeaderField{Name: ":status", Value: "200"})
-		t.hEnc.WriteField(hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
+		headerFields = append(headerFields, hpack.HeaderField{Name: ":status", Value: "200"})
+		headerFields = append(headerFields, hpack.HeaderField{Name: "content-type", Value: "application/grpc"})
 	}
-	t.hEnc.WriteField(
-		hpack.HeaderField{
-			Name:  "grpc-status",
-			Value: strconv.Itoa(int(st.Code())),
-		})
-	t.hEnc.WriteField(hpack.HeaderField{Name: "grpc-message", Value: encodeGrpcMessage(st.Message())})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-status", Value: strconv.Itoa(int(st.Code()))})
+	headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-message", Value: encodeGrpcMessage(st.Message())})
 
 	if p := st.Proto(); p != nil && len(p.Details) > 0 {
 		stBytes, err := proto.Marshal(p)
@@ -713,43 +786,42 @@ func (t *http2Server) WriteStatus(s *Stream, st *status.Status) error {
 			panic(err)
 		}
 
-		for k, v := range metadata.New(map[string]string{"grpc-status-details-bin": (string)(stBytes)}) {
-			for _, entry := range v {
-				t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
-			}
-		}
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-status-details-bin", Value: encodeBinHeader(stBytes)})
 	}
 
 	// Attach the trailer metadata.
-	for k, v := range s.trailer {
+	for k, vv := range s.trailer {
 		// Clients don't tolerate reading restricted headers after some non restricted ones were sent.
 		if isReservedHeader(k) {
 			continue
 		}
-		for _, entry := range v {
-			t.hEnc.WriteField(hpack.HeaderField{Name: k, Value: entry})
+		for _, v := range vv {
+			headerFields = append(headerFields, hpack.HeaderField{Name: k, Value: encodeMetadataHeader(k, v)})
 		}
 	}
-	bufLen := t.hBuf.Len()
-	if err := t.writeHeaders(s, t.hBuf, true); err != nil {
-		t.Close()
-		return err
-	}
+	t.controlBuf.put(&headerFrame{
+		streamID:  s.id,
+		hf:        headerFields,
+		endStream: true,
+	})
 	if t.stats != nil {
-		outTrailer := &stats.OutTrailer{
-			WireLength: bufLen,
-		}
-		t.stats.HandleRPC(s.Context(), outTrailer)
+		t.stats.HandleRPC(s.Context(), &stats.OutTrailer{})
 	}
 	t.closeStream(s)
-	t.writableChan <- 0
 	return nil
 }
 
 // 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, data []byte, opts *Options) (err error) {
-	// TODO(zhaoq): Support multi-writers for a single stream.
+func (t *http2Server) Write(s *Stream, hdr []byte, data []byte, opts *Options) (err error) {
+	select {
+	case <-s.ctx.Done():
+		return ContextErr(s.ctx.Err())
+	case <-t.ctx.Done():
+		return ErrConnClosing
+	default:
+	}
+
 	var writeHeaderFrame bool
 	s.mu.Lock()
 	if s.state == streamDone {
@@ -763,107 +835,81 @@ func (t *http2Server) Write(s *Stream, data []byte, opts *Options) (err error) {
 	if writeHeaderFrame {
 		t.WriteHeader(s, nil)
 	}
-	defer func() {
-		if err == nil {
+	// Add data to header frame so that we can equally distribute data across frames.
+	emptyLen := http2MaxFrameLen - len(hdr)
+	if emptyLen > len(data) {
+		emptyLen = len(data)
+	}
+	hdr = append(hdr, data[:emptyLen]...)
+	data = data[emptyLen:]
+	for _, r := range [][]byte{hdr, data} {
+		for len(r) > 0 {
+			size := http2MaxFrameLen
+			// Wait until the stream has some quota to send the data.
+			quotaChan, quotaVer := s.sendQuotaPool.acquireWithVersion()
+			sq, err := wait(s.ctx, t.ctx, nil, nil, quotaChan)
+			if err != nil {
+				return err
+			}
+			// Wait until the transport has some quota to send the data.
+			tq, err := wait(s.ctx, t.ctx, nil, nil, t.sendQuotaPool.acquire())
+			if err != nil {
+				return err
+			}
+			if sq < size {
+				size = sq
+			}
+			if tq < size {
+				size = tq
+			}
+			if size > len(r) {
+				size = len(r)
+			}
+			p := r[:size]
+			ps := len(p)
+			if ps < tq {
+				// Overbooked transport quota. Return it back.
+				t.sendQuotaPool.add(tq - ps)
+			}
+			// Acquire local send quota to be able to write to the controlBuf.
+			ltq, err := wait(s.ctx, t.ctx, nil, nil, s.localSendQuota.acquire())
+			if err != nil {
+				if _, ok := err.(ConnectionError); !ok {
+					t.sendQuotaPool.add(ps)
+				}
+				return err
+			}
+			s.localSendQuota.add(ltq - ps) // It's ok we make this negative.
 			// Reset ping strikes when sending data since this might cause
 			// the peer to send ping.
 			atomic.StoreUint32(&t.resetPingStrikes, 1)
-		}
-	}()
-	r := bytes.NewBuffer(data)
-	for {
-		if r.Len() == 0 {
-			return nil
-		}
-		size := http2MaxFrameLen
-		// Wait until the stream has some quota to send the data.
-		sq, err := wait(s.ctx, nil, nil, t.shutdownChan, s.sendQuotaPool.acquire())
-		if err != nil {
-			return err
-		}
-		// Wait until the transport has some quota to send the data.
-		tq, err := wait(s.ctx, nil, nil, t.shutdownChan, t.sendQuotaPool.acquire())
-		if err != nil {
-			return err
-		}
-		if sq < size {
-			size = sq
-		}
-		if tq < size {
-			size = tq
-		}
-		p := r.Next(size)
-		ps := len(p)
-		if ps < sq {
-			// Overbooked stream quota. Return it back.
-			s.sendQuotaPool.add(sq - ps)
-		}
-		if ps < tq {
-			// Overbooked transport quota. Return it back.
-			t.sendQuotaPool.add(tq - ps)
-		}
-		t.framer.adjustNumWriters(1)
-		// Got some quota. Try to acquire writing privilege on the
-		// transport.
-		if _, err := wait(s.ctx, nil, nil, t.shutdownChan, t.writableChan); err != nil {
-			if _, ok := err.(StreamError); ok {
-				// Return the connection quota back.
-				t.sendQuotaPool.add(ps)
-			}
-			if t.framer.adjustNumWriters(-1) == 0 {
-				// This writer is the last one in this batch and has the
-				// responsibility to flush the buffered frames. It queues
-				// a flush request to controlBuf instead of flushing directly
-				// in order to avoid the race with other writing or flushing.
-				t.controlBuf.put(&flushIO{})
+			success := func() {
+				t.controlBuf.put(&dataFrame{streamID: s.id, endStream: false, d: p, f: func() {
+					s.localSendQuota.add(ps)
+				}})
+				if ps < sq {
+					// Overbooked stream quota. Return it back.
+					s.sendQuotaPool.lockedAdd(sq - ps)
+				}
+				r = r[ps:]
 			}
-			return err
-		}
-		select {
-		case <-s.ctx.Done():
-			t.sendQuotaPool.add(ps)
-			if t.framer.adjustNumWriters(-1) == 0 {
-				t.controlBuf.put(&flushIO{})
+			failure := func() {
+				s.sendQuotaPool.lockedAdd(sq)
 			}
-			t.writableChan <- 0
-			return ContextErr(s.ctx.Err())
-		default:
-		}
-		var forceFlush bool
-		if r.Len() == 0 && t.framer.adjustNumWriters(0) == 1 && !opts.Last {
-			forceFlush = true
-		}
-		if err := t.framer.writeData(forceFlush, s.id, false, p); err != nil {
-			t.Close()
-			return connectionErrorf(true, err, "transport: %v", err)
-		}
-		if t.framer.adjustNumWriters(-1) == 0 {
-			t.framer.flushWrite()
-		}
-		t.writableChan <- 0
-	}
-
-}
-
-func (t *http2Server) applySettings(ss []http2.Setting) {
-	for _, s := range ss {
-		if s.ID == http2.SettingInitialWindowSize {
-			t.mu.Lock()
-			defer t.mu.Unlock()
-			for _, stream := range t.activeStreams {
-				stream.sendQuotaPool.add(int(s.Val - t.streamSendQuota))
+			if !s.sendQuotaPool.compareAndExecute(quotaVer, success, failure) {
+				t.sendQuotaPool.add(ps)
+				s.localSendQuota.add(ps)
 			}
-			t.streamSendQuota = s.Val
 		}
-
 	}
+	return nil
 }
 
 // keepalive running in a separate goroutine does the following:
 // 1. Gracefully closes an idle connection after a duration of keepalive.MaxConnectionIdle.
 // 2. Gracefully closes any connection after a duration of keepalive.MaxConnectionAge.
 // 3. Forcibly closes a connection after an additive period of keepalive.MaxConnectionAgeGrace over keepalive.MaxConnectionAge.
-// 4. Makes sure a connection is alive by sending pings with a frequency of keepalive.Time and closes a non-resposive connection
+// 4. Makes sure a connection is alive by sending pings with a frequency of keepalive.Time and closes a non-responsive connection
 // after an additional duration of keepalive.Timeout.
 func (t *http2Server) keepalive() {
 	p := &ping{}
@@ -872,7 +918,7 @@ func (t *http2Server) keepalive() {
 	maxAge := time.NewTimer(t.kp.MaxConnectionAge)
 	keepalive := time.NewTimer(t.kp.Time)
 	// NOTE: All exit paths of this function should reset their
-	// respecitve timers. A failure to do so will cause the
+	// respective timers. A failure to do so will cause the
 	// following clean-up to deadlock and eventually leak.
 	defer func() {
 		if !maxIdle.Stop() {
@@ -896,23 +942,18 @@ func (t *http2Server) keepalive() {
 				continue
 			}
 			val := t.kp.MaxConnectionIdle - time.Since(idle)
+			t.mu.Unlock()
 			if val <= 0 {
 				// The connection has been idle for a duration of keepalive.MaxConnectionIdle or more.
 				// Gracefully close the connection.
-				t.state = draining
-				t.mu.Unlock()
-				t.Drain()
+				t.drain(http2.ErrCodeNo, []byte{})
 				// Reseting the timer so that the clean-up doesn't deadlock.
 				maxIdle.Reset(infinity)
 				return
 			}
-			t.mu.Unlock()
 			maxIdle.Reset(val)
 		case <-maxAge.C:
-			t.mu.Lock()
-			t.state = draining
-			t.mu.Unlock()
-			t.Drain()
+			t.drain(http2.ErrCodeNo, []byte{})
 			maxAge.Reset(t.kp.MaxConnectionAgeGrace)
 			select {
 			case <-maxAge.C:
@@ -920,7 +961,7 @@ func (t *http2Server) keepalive() {
 				t.Close()
 				// Reseting the timer so that the clean-up doesn't deadlock.
 				maxAge.Reset(infinity)
-			case <-t.shutdownChan:
+			case <-t.ctx.Done():
 			}
 			return
 		case <-keepalive.C:
@@ -938,69 +979,137 @@ func (t *http2Server) keepalive() {
 			pingSent = true
 			t.controlBuf.put(p)
 			keepalive.Reset(t.kp.Timeout)
-		case <-t.shutdownChan:
+		case <-t.ctx.Done():
 			return
 		}
 	}
 }
 
-// controller running in a separate goroutine takes charge of sending control
-// frames (e.g., window update, reset stream, setting, etc.) to the server.
-func (t *http2Server) controller() {
-	for {
-		select {
-		case i := <-t.controlBuf.get():
-			t.controlBuf.load()
+var goAwayPing = &ping{data: [8]byte{1, 6, 1, 8, 0, 3, 3, 9}}
+
+// TODO(mmukhi): A lot of this code(and code in other places in the tranpsort layer)
+// is duplicated between the client and the server.
+// The transport layer needs to be refactored to take care of this.
+func (t *http2Server) itemHandler(i item) error {
+	switch i := i.(type) {
+	case *dataFrame:
+		if err := t.framer.fr.WriteData(i.streamID, i.endStream, i.d); err != nil {
+			return err
+		}
+		i.f()
+		return nil
+	case *headerFrame:
+		t.hBuf.Reset()
+		for _, f := range i.hf {
+			t.hEnc.WriteField(f)
+		}
+		first := true
+		endHeaders := false
+		for !endHeaders {
+			size := t.hBuf.Len()
+			if size > http2MaxFrameLen {
+				size = http2MaxFrameLen
+			} else {
+				endHeaders = true
+			}
+			var err error
+			if first {
+				first = false
+				err = t.framer.fr.WriteHeaders(http2.HeadersFrameParam{
+					StreamID:      i.streamID,
+					BlockFragment: t.hBuf.Next(size),
+					EndStream:     i.endStream,
+					EndHeaders:    endHeaders,
+				})
+			} else {
+				err = t.framer.fr.WriteContinuation(
+					i.streamID,
+					endHeaders,
+					t.hBuf.Next(size),
+				)
+			}
+			if err != nil {
+				return err
+			}
+		}
+		atomic.StoreUint32(&t.resetPingStrikes, 1)
+		return nil
+	case *windowUpdate:
+		return t.framer.fr.WriteWindowUpdate(i.streamID, i.increment)
+	case *settings:
+		if i.ack {
+			t.applySettings(i.ss)
+			return t.framer.fr.WriteSettingsAck()
+		}
+		return t.framer.fr.WriteSettings(i.ss...)
+	case *resetStream:
+		return t.framer.fr.WriteRSTStream(i.streamID, i.code)
+	case *goAway:
+		t.mu.Lock()
+		if t.state == closing {
+			t.mu.Unlock()
+			// The transport is closing.
+			return fmt.Errorf("transport: Connection closing")
+		}
+		sid := t.maxStreamID
+		if !i.headsUp {
+			// Stop accepting more streams now.
+			t.state = draining
+			t.mu.Unlock()
+			if err := t.framer.fr.WriteGoAway(sid, i.code, i.debugData); err != nil {
+				return err
+			}
+			if i.closeConn {
+				// Abruptly close the connection following the GoAway (via
+				// loopywriter).  But flush out what's inside the buffer first.
+				t.framer.writer.Flush()
+				return fmt.Errorf("transport: Connection closing")
+			}
+			return nil
+		}
+		t.mu.Unlock()
+		// For a graceful close, send out a GoAway with stream ID of MaxUInt32,
+		// Follow that with a ping and wait for the ack to come back or a timer
+		// to expire. During this time accept new streams since they might have
+		// originated before the GoAway reaches the client.
+		// After getting the ack or timer expiration send out another GoAway this
+		// time with an ID of the max stream server intends to process.
+		if err := t.framer.fr.WriteGoAway(math.MaxUint32, http2.ErrCodeNo, []byte{}); err != nil {
+			return err
+		}
+		if err := t.framer.fr.WritePing(false, goAwayPing.data); err != nil {
+			return err
+		}
+		go func() {
+			timer := time.NewTimer(time.Minute)
+			defer timer.Stop()
 			select {
-			case <-t.writableChan:
-				switch i := i.(type) {
-				case *windowUpdate:
-					t.framer.writeWindowUpdate(true, i.streamID, i.increment)
-				case *settings:
-					if i.ack {
-						t.framer.writeSettingsAck(true)
-						t.applySettings(i.ss)
-					} else {
-						t.framer.writeSettings(true, i.ss...)
-					}
-				case *resetStream:
-					t.framer.writeRSTStream(true, i.streamID, i.code)
-				case *goAway:
-					t.mu.Lock()
-					if t.state == closing {
-						t.mu.Unlock()
-						// The transport is closing.
-						return
-					}
-					sid := t.maxStreamID
-					t.state = draining
-					t.mu.Unlock()
-					t.framer.writeGoAway(true, sid, i.code, i.debugData)
-					if i.code == http2.ErrCodeEnhanceYourCalm {
-						t.Close()
-					}
-				case *flushIO:
-					t.framer.flushWrite()
-				case *ping:
-					t.framer.writePing(true, i.ack, i.data)
-				default:
-					grpclog.Printf("transport: http2Server.controller got unexpected item type %v\n", i)
-				}
-				t.writableChan <- 0
-				continue
-			case <-t.shutdownChan:
+			case <-t.drainChan:
+			case <-timer.C:
+			case <-t.ctx.Done():
 				return
 			}
-		case <-t.shutdownChan:
-			return
+			t.controlBuf.put(&goAway{code: i.code, debugData: i.debugData})
+		}()
+		return nil
+	case *flushIO:
+		return t.framer.writer.Flush()
+	case *ping:
+		if !i.ack {
+			t.bdpEst.timesnap(i.data)
 		}
+		return t.framer.fr.WritePing(i.ack, i.data)
+	default:
+		err := status.Errorf(codes.Internal, "transport: http2Server.controller got unexpected item type %t", i)
+		errorf("%v", err)
+		return err
 	}
 }
 
 // Close starts shutting down the http2Server transport.
 // TODO(zhaoq): Now the destruction is not blocked on any pending streams. This
 // could cause some resource issue. Revisit this later.
-func (t *http2Server) Close() (err error) {
+func (t *http2Server) Close() error {
 	t.mu.Lock()
 	if t.state == closing {
 		t.mu.Unlock()
@@ -1010,8 +1119,8 @@ func (t *http2Server) Close() (err error) {
 	streams := t.activeStreams
 	t.activeStreams = nil
 	t.mu.Unlock()
-	close(t.shutdownChan)
-	err = t.conn.Close()
+	t.cancel()
+	err := t.conn.Close()
 	// Cancel all active streams.
 	for _, s := range streams {
 		s.cancel()
@@ -1020,7 +1129,7 @@ func (t *http2Server) Close() (err error) {
 		connEnd := &stats.ConnEnd{}
 		t.stats.HandleConn(t.ctx, connEnd)
 	}
-	return
+	return err
 }
 
 // closeStream clears the footprint of a stream when the stream is not needed
@@ -1040,11 +1149,6 @@ func (t *http2Server) closeStream(s *Stream) {
 	// called to interrupt the potential blocking on other goroutines.
 	s.cancel()
 	s.mu.Lock()
-	if q := s.fc.resetPendingData(); q > 0 {
-		if w := t.fc.onRead(q); w > 0 {
-			t.controlBuf.put(&windowUpdate{0, w})
-		}
-	}
 	if s.state == streamDone {
 		s.mu.Unlock()
 		return
@@ -1058,7 +1162,17 @@ func (t *http2Server) RemoteAddr() net.Addr {
 }
 
 func (t *http2Server) Drain() {
-	t.controlBuf.put(&goAway{code: http2.ErrCodeNo})
+	t.drain(http2.ErrCodeNo, []byte{})
+}
+
+func (t *http2Server) drain(code http2.ErrCode, debugData []byte) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.drainChan != nil {
+		return
+	}
+	t.drainChan = make(chan struct{})
+	t.controlBuf.put(&goAway{code: code, debugData: debugData, headsUp: true})
 }
 
 var rgen = rand.New(rand.NewSource(time.Now().UnixNano()))
diff --git a/vendor/google.golang.org/grpc/transport/http_util.go b/vendor/google.golang.org/grpc/transport/http_util.go
index 6adef77..39f878c 100644
--- a/vendor/google.golang.org/grpc/transport/http_util.go
+++ b/vendor/google.golang.org/grpc/transport/http_util.go
@@ -1,33 +1,18 @@
 /*
  *
- * Copyright 2014, Google Inc.
- * All rights reserved.
+ * Copyright 2014 gRPC authors.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
+ * 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
  *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 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.
  *
  */
 
@@ -36,12 +21,13 @@ package transport
 import (
 	"bufio"
 	"bytes"
+	"encoding/base64"
 	"fmt"
 	"io"
 	"net"
+	"net/http"
 	"strconv"
 	"strings"
-	"sync/atomic"
 	"time"
 
 	"github.com/golang/protobuf/proto"
@@ -49,8 +35,6 @@ import (
 	"golang.org/x/net/http2/hpack"
 	spb "google.golang.org/genproto/googleapis/rpc/status"
 	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/grpclog"
-	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 )
 
@@ -60,7 +44,8 @@ const (
 	// http://http2.github.io/http2-spec/#SettingValues
 	http2InitHeaderTableSize = 4096
 	// http2IOBufSize specifies the buffer size for sending frames.
-	http2IOBufSize = 32 * 1024
+	defaultWriteBufSize = 32 * 1024
+	defaultReadBufSize  = 32 * 1024
 )
 
 var (
@@ -88,6 +73,24 @@ var (
 		codes.ResourceExhausted: http2.ErrCodeEnhanceYourCalm,
 		codes.PermissionDenied:  http2.ErrCodeInadequateSecurity,
 	}
+	httpStatusConvTab = map[int]codes.Code{
+		// 400 Bad Request - INTERNAL.
+		http.StatusBadRequest: codes.Internal,
+		// 401 Unauthorized  - UNAUTHENTICATED.
+		http.StatusUnauthorized: codes.Unauthenticated,
+		// 403 Forbidden - PERMISSION_DENIED.
+		http.StatusForbidden: codes.PermissionDenied,
+		// 404 Not Found - UNIMPLEMENTED.
+		http.StatusNotFound: codes.Unimplemented,
+		// 429 Too Many Requests - UNAVAILABLE.
+		http.StatusTooManyRequests: codes.Unavailable,
+		// 502 Bad Gateway - UNAVAILABLE.
+		http.StatusBadGateway: codes.Unavailable,
+		// 503 Service Unavailable - UNAVAILABLE.
+		http.StatusServiceUnavailable: codes.Unavailable,
+		// 504 Gateway timeout - UNAVAILABLE.
+		http.StatusGatewayTimeout: codes.Unavailable,
+	}
 )
 
 // Records the states during HPACK decoding. Must be reset once the
@@ -100,14 +103,17 @@ type decodeState struct {
 	statusGen *status.Status
 	// rawStatusCode and rawStatusMsg are set from the raw trailer fields and are not
 	// intended for direct access outside of parsing.
-	rawStatusCode int32
+	rawStatusCode *int
 	rawStatusMsg  string
+	httpStatus    *int
 	// Server side only fields.
 	timeoutSet bool
 	timeout    time.Duration
 	method     string
 	// key-value metadata map from the peer.
-	mdata map[string][]string
+	mdata      map[string][]string
+	statsTags  []byte
+	statsTrace []byte
 }
 
 // isReservedHeader checks whether hdr belongs to HTTP2 headers
@@ -159,11 +165,85 @@ func validContentType(t string) bool {
 func (d *decodeState) status() *status.Status {
 	if d.statusGen == nil {
 		// No status-details were provided; generate status using code/msg.
-		d.statusGen = status.New(codes.Code(d.rawStatusCode), d.rawStatusMsg)
+		d.statusGen = status.New(codes.Code(int32(*(d.rawStatusCode))), d.rawStatusMsg)
 	}
 	return d.statusGen
 }
 
+const binHdrSuffix = "-bin"
+
+func encodeBinHeader(v []byte) string {
+	return base64.RawStdEncoding.EncodeToString(v)
+}
+
+func decodeBinHeader(v string) ([]byte, error) {
+	if len(v)%4 == 0 {
+		// Input was padded, or padding was not necessary.
+		return base64.StdEncoding.DecodeString(v)
+	}
+	return base64.RawStdEncoding.DecodeString(v)
+}
+
+func encodeMetadataHeader(k, v string) string {
+	if strings.HasSuffix(k, binHdrSuffix) {
+		return encodeBinHeader(([]byte)(v))
+	}
+	return v
+}
+
+func decodeMetadataHeader(k, v string) (string, error) {
+	if strings.HasSuffix(k, binHdrSuffix) {
+		b, err := decodeBinHeader(v)
+		return string(b), err
+	}
+	return v, nil
+}
+
+func (d *decodeState) decodeResponseHeader(frame *http2.MetaHeadersFrame) error {
+	for _, hf := range frame.Fields {
+		if err := d.processHeaderField(hf); err != nil {
+			return err
+		}
+	}
+
+	// If grpc status exists, no need to check further.
+	if d.rawStatusCode != nil || d.statusGen != nil {
+		return nil
+	}
+
+	// If grpc status doesn't exist and http status doesn't exist,
+	// then it's a malformed header.
+	if d.httpStatus == nil {
+		return streamErrorf(codes.Internal, "malformed header: doesn't contain status(gRPC or HTTP)")
+	}
+
+	if *(d.httpStatus) != http.StatusOK {
+		code, ok := httpStatusConvTab[*(d.httpStatus)]
+		if !ok {
+			code = codes.Unknown
+		}
+		return streamErrorf(code, http.StatusText(*(d.httpStatus)))
+	}
+
+	// gRPC status doesn't exist and http status is OK.
+	// Set rawStatusCode to be unknown and return nil error.
+	// So that, if the stream has ended this Unknown status
+	// will be propogated to the user.
+	// Otherwise, it will be ignored. In which case, status from
+	// a later trailer, that has StreamEnded flag set, is propogated.
+	code := int(codes.Unknown)
+	d.rawStatusCode = &code
+	return nil
+
+}
+
+func (d *decodeState) addMetadata(k, v string) {
+	if d.mdata == nil {
+		d.mdata = make(map[string][]string)
+	}
+	d.mdata[k] = append(d.mdata[k], v)
+}
+
 func (d *decodeState) processHeaderField(f hpack.HeaderField) error {
 	switch f.Name {
 	case "content-type":
@@ -177,16 +257,16 @@ func (d *decodeState) processHeaderField(f hpack.HeaderField) error {
 		if err != nil {
 			return streamErrorf(codes.Internal, "transport: malformed grpc-status: %v", err)
 		}
-		d.rawStatusCode = int32(code)
+		d.rawStatusCode = &code
 	case "grpc-message":
 		d.rawStatusMsg = decodeGrpcMessage(f.Value)
 	case "grpc-status-details-bin":
-		_, v, err := metadata.DecodeKeyValue("grpc-status-details-bin", f.Value)
+		v, err := decodeBinHeader(f.Value)
 		if err != nil {
 			return streamErrorf(codes.Internal, "transport: malformed grpc-status-details-bin: %v", err)
 		}
 		s := &spb.Status{}
-		if err := proto.Unmarshal([]byte(v), s); err != nil {
+		if err := proto.Unmarshal(v, s); err != nil {
 			return streamErrorf(codes.Internal, "transport: malformed grpc-status-details-bin: %v", err)
 		}
 		d.statusGen = status.FromProto(s)
@@ -198,18 +278,36 @@ func (d *decodeState) processHeaderField(f hpack.HeaderField) error {
 		}
 	case ":path":
 		d.method = f.Value
+	case ":status":
+		code, err := strconv.Atoi(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed http-status: %v", err)
+		}
+		d.httpStatus = &code
+	case "grpc-tags-bin":
+		v, err := decodeBinHeader(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed grpc-tags-bin: %v", err)
+		}
+		d.statsTags = v
+		d.addMetadata(f.Name, string(v))
+	case "grpc-trace-bin":
+		v, err := decodeBinHeader(f.Value)
+		if err != nil {
+			return streamErrorf(codes.Internal, "transport: malformed grpc-trace-bin: %v", err)
+		}
+		d.statsTrace = v
+		d.addMetadata(f.Name, string(v))
 	default:
-		if !isReservedHeader(f.Name) || isWhitelistedPseudoHeader(f.Name) {
-			if d.mdata == nil {
-				d.mdata = make(map[string][]string)
-			}
-			k, v, err := metadata.DecodeKeyValue(f.Name, f.Value)
-			if err != nil {
-				grpclog.Printf("Failed to decode (%q, %q): %v", f.Name, f.Value, err)
-				return nil
-			}
-			d.mdata[k] = append(d.mdata[k], v)
+		if isReservedHeader(f.Name) && !isWhitelistedPseudoHeader(f.Name) {
+			break
 		}
+		v, err := decodeMetadataHeader(f.Name, f.Value)
+		if err != nil {
+			errorf("Failed to decode metadata header (%q, %q): %v", f.Name, f.Value, err)
+			return nil
+		}
+		d.addMetadata(f.Name, string(v))
 	}
 	return nil
 }
@@ -377,141 +475,15 @@ type framer struct {
 	fr         *http2.Framer
 }
 
-func newFramer(conn net.Conn) *framer {
+func newFramer(conn net.Conn, writeBufferSize, readBufferSize int) *framer {
 	f := &framer{
-		reader: bufio.NewReaderSize(conn, http2IOBufSize),
-		writer: bufio.NewWriterSize(conn, http2IOBufSize),
+		reader: bufio.NewReaderSize(conn, readBufferSize),
+		writer: bufio.NewWriterSize(conn, writeBufferSize),
 	}
 	f.fr = http2.NewFramer(f.writer, f.reader)
+	// Opt-in to Frame reuse API on framer to reduce garbage.
+	// Frames aren't safe to read from after a subsequent call to ReadFrame.
+	f.fr.SetReuseFrames()
 	f.fr.ReadMetaHeaders = hpack.NewDecoder(http2InitHeaderTableSize, nil)
 	return f
 }
-
-func (f *framer) adjustNumWriters(i int32) int32 {
-	return atomic.AddInt32(&f.numWriters, i)
-}
-
-// The following writeXXX functions can only be called when the caller gets
-// unblocked from writableChan channel (i.e., owns the privilege to write).
-
-func (f *framer) writeContinuation(forceFlush bool, streamID uint32, endHeaders bool, headerBlockFragment []byte) error {
-	if err := f.fr.WriteContinuation(streamID, endHeaders, headerBlockFragment); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writeData(forceFlush bool, streamID uint32, endStream bool, data []byte) error {
-	if err := f.fr.WriteData(streamID, endStream, data); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writeGoAway(forceFlush bool, maxStreamID uint32, code http2.ErrCode, debugData []byte) error {
-	if err := f.fr.WriteGoAway(maxStreamID, code, debugData); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writeHeaders(forceFlush bool, p http2.HeadersFrameParam) error {
-	if err := f.fr.WriteHeaders(p); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writePing(forceFlush, ack bool, data [8]byte) error {
-	if err := f.fr.WritePing(ack, data); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writePriority(forceFlush bool, streamID uint32, p http2.PriorityParam) error {
-	if err := f.fr.WritePriority(streamID, p); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writePushPromise(forceFlush bool, p http2.PushPromiseParam) error {
-	if err := f.fr.WritePushPromise(p); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writeRSTStream(forceFlush bool, streamID uint32, code http2.ErrCode) error {
-	if err := f.fr.WriteRSTStream(streamID, code); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writeSettings(forceFlush bool, settings ...http2.Setting) error {
-	if err := f.fr.WriteSettings(settings...); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writeSettingsAck(forceFlush bool) error {
-	if err := f.fr.WriteSettingsAck(); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) writeWindowUpdate(forceFlush bool, streamID, incr uint32) error {
-	if err := f.fr.WriteWindowUpdate(streamID, incr); err != nil {
-		return err
-	}
-	if forceFlush {
-		return f.writer.Flush()
-	}
-	return nil
-}
-
-func (f *framer) flushWrite() error {
-	return f.writer.Flush()
-}
-
-func (f *framer) readFrame() (http2.Frame, error) {
-	return f.fr.ReadFrame()
-}
-
-func (f *framer) errorDetail() error {
-	return f.fr.ErrorDetail()
-}
diff --git a/vendor/google.golang.org/grpc/transport/log.go b/vendor/google.golang.org/grpc/transport/log.go
new file mode 100644
index 0000000..ac8e358
--- /dev/null
+++ b/vendor/google.golang.org/grpc/transport/log.go
@@ -0,0 +1,50 @@
+/*
+ *
+ * Copyright 2017 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.
+ *
+ */
+
+// This file contains wrappers for grpclog functions.
+// The transport package only logs to verbose level 2 by default.
+
+package transport
+
+import "google.golang.org/grpc/grpclog"
+
+const logLevel = 2
+
+func infof(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Infof(format, args...)
+	}
+}
+
+func warningf(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Warningf(format, args...)
+	}
+}
+
+func errorf(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Errorf(format, args...)
+	}
+}
+
+func fatalf(format string, args ...interface{}) {
+	if grpclog.V(logLevel) {
+		grpclog.Fatalf(format, args...)
+	}
+}
diff --git a/vendor/google.golang.org/grpc/transport/transport.go b/vendor/google.golang.org/grpc/transport/transport.go
index b62f702..2cf9bd3 100644
--- a/vendor/google.golang.org/grpc/transport/transport.go
+++ b/vendor/google.golang.org/grpc/transport/transport.go
@@ -1,48 +1,32 @@
 /*
  *
- * Copyright 2014, Google Inc.
- * All rights reserved.
+ * Copyright 2014 gRPC authors.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
+ * 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
  *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 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 defines and implements message oriented communication channel
-to complete various transactions (e.g., an RPC).
-*/
+// Package transport defines and implements message oriented communication
+// channel to complete various transactions (e.g., an RPC).
 package transport // import "google.golang.org/grpc/transport"
 
 import (
-	"bytes"
+	stdctx "context"
 	"fmt"
 	"io"
 	"net"
 	"sync"
+	"time"
 
 	"golang.org/x/net/context"
 	"golang.org/x/net/http2"
@@ -65,57 +49,56 @@ type recvMsg struct {
 	err error
 }
 
-func (*recvMsg) item() {}
-
-// All items in an out of a recvBuffer should be the same type.
-type item interface {
-	item()
-}
-
-// recvBuffer is an unbounded channel of item.
+// recvBuffer is an unbounded channel of recvMsg structs.
+// Note recvBuffer differs from controlBuffer only in that recvBuffer
+// holds a channel of only recvMsg structs instead of objects implementing "item" interface.
+// recvBuffer is written to much more often than
+// controlBuffer and using strict recvMsg structs helps avoid allocation in "recvBuffer.put"
 type recvBuffer struct {
-	c       chan item
+	c       chan recvMsg
 	mu      sync.Mutex
-	backlog []item
+	backlog []recvMsg
 }
 
 func newRecvBuffer() *recvBuffer {
 	b := &recvBuffer{
-		c: make(chan item, 1),
+		c: make(chan recvMsg, 1),
 	}
 	return b
 }
 
-func (b *recvBuffer) put(r item) {
+func (b *recvBuffer) put(r recvMsg) {
 	b.mu.Lock()
-	defer b.mu.Unlock()
 	if len(b.backlog) == 0 {
 		select {
 		case b.c <- r:
+			b.mu.Unlock()
 			return
 		default:
 		}
 	}
 	b.backlog = append(b.backlog, r)
+	b.mu.Unlock()
 }
 
 func (b *recvBuffer) load() {
 	b.mu.Lock()
-	defer b.mu.Unlock()
 	if len(b.backlog) > 0 {
 		select {
 		case b.c <- b.backlog[0]:
+			b.backlog[0] = recvMsg{}
 			b.backlog = b.backlog[1:]
 		default:
 		}
 	}
+	b.mu.Unlock()
 }
 
-// get returns the channel that receives an item in the buffer.
+// get returns the channel that receives a recvMsg in the buffer.
 //
-// Upon receipt of an item, the caller should call load to send another
-// item onto the channel if there is any.
-func (b *recvBuffer) get() <-chan item {
+// Upon receipt of a recvMsg, the caller should call load to send another
+// recvMsg onto the channel if there is any.
+func (b *recvBuffer) get() <-chan recvMsg {
 	return b.c
 }
 
@@ -125,7 +108,7 @@ type recvBufferReader struct {
 	ctx    context.Context
 	goAway chan struct{}
 	recv   *recvBuffer
-	last   *bytes.Reader // Stores the remaining data in the previous calls.
+	last   []byte // Stores the remaining data in the previous calls.
 	err    error
 }
 
@@ -136,27 +119,87 @@ func (r *recvBufferReader) Read(p []byte) (n int, err error) {
 	if r.err != nil {
 		return 0, r.err
 	}
-	defer func() { r.err = err }()
-	if r.last != nil && r.last.Len() > 0 {
+	n, r.err = r.read(p)
+	return n, r.err
+}
+
+func (r *recvBufferReader) read(p []byte) (n int, err error) {
+	if r.last != nil && len(r.last) > 0 {
 		// Read remaining data left in last call.
-		return r.last.Read(p)
+		copied := copy(p, r.last)
+		r.last = r.last[copied:]
+		return copied, nil
 	}
 	select {
 	case <-r.ctx.Done():
 		return 0, ContextErr(r.ctx.Err())
 	case <-r.goAway:
 		return 0, ErrStreamDrain
-	case i := <-r.recv.get():
+	case m := <-r.recv.get():
 		r.recv.load()
-		m := i.(*recvMsg)
 		if m.err != nil {
 			return 0, m.err
 		}
-		r.last = bytes.NewReader(m.data)
-		return r.last.Read(p)
+		copied := copy(p, m.data)
+		r.last = m.data[copied:]
+		return copied, nil
 	}
 }
 
+// All items in an out of a controlBuffer should be the same type.
+type item interface {
+	item()
+}
+
+// controlBuffer is an unbounded channel of item.
+type controlBuffer struct {
+	c       chan item
+	mu      sync.Mutex
+	backlog []item
+}
+
+func newControlBuffer() *controlBuffer {
+	b := &controlBuffer{
+		c: make(chan item, 1),
+	}
+	return b
+}
+
+func (b *controlBuffer) put(r item) {
+	b.mu.Lock()
+	if len(b.backlog) == 0 {
+		select {
+		case b.c <- r:
+			b.mu.Unlock()
+			return
+		default:
+		}
+	}
+	b.backlog = append(b.backlog, r)
+	b.mu.Unlock()
+}
+
+func (b *controlBuffer) load() {
+	b.mu.Lock()
+	if len(b.backlog) > 0 {
+		select {
+		case b.c <- b.backlog[0]:
+			b.backlog[0] = nil
+			b.backlog = b.backlog[1:]
+		default:
+		}
+	}
+	b.mu.Unlock()
+}
+
+// get returns the channel that receives an item in the buffer.
+//
+// Upon receipt of an item, the caller should call load to send another
+// item onto the channel if there is any.
+func (b *controlBuffer) get() <-chan item {
+	return b.c
+}
+
 type streamState uint8
 
 const (
@@ -171,11 +214,6 @@ type Stream struct {
 	id uint32
 	// nil for client side Stream.
 	st ServerTransport
-	// clientStatsCtx keeps the user context for stats handling.
-	// It's only valid on client side. Server side stats context is same as s.ctx.
-	// All client side stats collection should use the clientStatsCtx (instead of the stream context)
-	// so that all the generated stats for a particular RPC can be associated in the processing phase.
-	clientStatsCtx context.Context
 	// ctx is the associated context of the stream.
 	ctx context.Context
 	// cancel is always nil for client side Stream.
@@ -189,16 +227,20 @@ type Stream struct {
 	recvCompress string
 	sendCompress string
 	buf          *recvBuffer
-	dec          io.Reader
+	trReader     io.Reader
 	fc           *inFlow
 	recvQuota    uint32
+
+	// TODO: Remote this unused variable.
 	// The accumulated inbound quota pending for window update.
 	updateQuota uint32
-	// The handler to control the window update procedure for both this
-	// particular stream and the associated transport.
-	windowHandler func(int)
 
-	sendQuotaPool *quotaPool
+	// Callback to state application's intentions to read data. This
+	// is used to adjust flow control, if need be.
+	requestRead func(int)
+
+	sendQuotaPool  *quotaPool
+	localSendQuota *quotaPool
 	// Close headerChan to indicate the end of reception of header metadata.
 	headerChan chan struct{}
 	// header caches the received header metadata.
@@ -220,6 +262,10 @@ type Stream struct {
 	rstStream bool
 	// rstError is the error that needs to be sent along with the RST_STREAM frame.
 	rstError http2.ErrCode
+	// bytesSent and bytesReceived indicates whether any bytes have been sent or
+	// received on this stream.
+	bytesSent     bool
+	bytesReceived bool
 }
 
 // RecvCompress returns the compression algorithm applied to the inbound
@@ -247,16 +293,24 @@ func (s *Stream) GoAway() <-chan struct{} {
 
 // Header acquires the key-value pairs of header metadata once it
 // is available. It blocks until i) the metadata is ready or ii) there is no
-// header metadata or iii) the stream is cancelled/expired.
+// header metadata or iii) the stream is canceled/expired.
 func (s *Stream) Header() (metadata.MD, error) {
+	var err error
 	select {
 	case <-s.ctx.Done():
-		return nil, ContextErr(s.ctx.Err())
+		err = ContextErr(s.ctx.Err())
 	case <-s.goAway:
-		return nil, ErrStreamDrain
+		err = ErrStreamDrain
+	case <-s.headerChan:
+		return s.header.Copy(), nil
+	}
+	// Even if the stream is closed, header is returned if available.
+	select {
 	case <-s.headerChan:
 		return s.header.Copy(), nil
+	default:
 	}
+	return nil, err
 }
 
 // Trailer returns the cached trailer metedata. Note that if it is not called
@@ -264,8 +318,9 @@ func (s *Stream) Header() (metadata.MD, error) {
 // side only.
 func (s *Stream) Trailer() metadata.MD {
 	s.mu.RLock()
-	defer s.mu.RUnlock()
-	return s.trailer.Copy()
+	c := s.trailer.Copy()
+	s.mu.RUnlock()
+	return c
 }
 
 // ServerTransport returns the underlying ServerTransport for the stream.
@@ -293,14 +348,16 @@ func (s *Stream) Status() *status.Status {
 // Server side only.
 func (s *Stream) SetHeader(md metadata.MD) error {
 	s.mu.Lock()
-	defer s.mu.Unlock()
 	if s.headerOk || s.state == streamDone {
+		s.mu.Unlock()
 		return ErrIllegalHeaderWrite
 	}
 	if md.Len() == 0 {
+		s.mu.Unlock()
 		return nil
 	}
 	s.header = metadata.Join(s.header, md)
+	s.mu.Unlock()
 	return nil
 }
 
@@ -311,25 +368,44 @@ func (s *Stream) SetTrailer(md metadata.MD) error {
 		return nil
 	}
 	s.mu.Lock()
-	defer s.mu.Unlock()
 	s.trailer = metadata.Join(s.trailer, md)
+	s.mu.Unlock()
 	return nil
 }
 
 func (s *Stream) write(m recvMsg) {
-	s.buf.put(&m)
+	s.buf.put(m)
 }
 
-// Read reads all the data available for this Stream from the transport and
+// Read reads all p bytes from the wire for this stream.
+func (s *Stream) Read(p []byte) (n int, err error) {
+	// Don't request a read if there was an error earlier
+	if er := s.trReader.(*transportReader).er; er != nil {
+		return 0, er
+	}
+	s.requestRead(len(p))
+	return io.ReadFull(s.trReader, p)
+}
+
+// tranportReader 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.
-func (s *Stream) Read(p []byte) (n int, err error) {
-	n, err = s.dec.Read(p)
+type transportReader struct {
+	reader io.Reader
+	// 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)
 	if err != nil {
+		t.er = err
 		return
 	}
-	s.windowHandler(n)
+	t.windowHandler(n)
 	return
 }
 
@@ -341,6 +417,22 @@ func (s *Stream) finish(st *status.Status) {
 	close(s.done)
 }
 
+// BytesSent indicates whether any bytes have been sent on this stream.
+func (s *Stream) BytesSent() bool {
+	s.mu.Lock()
+	bs := s.bytesSent
+	s.mu.Unlock()
+	return bs
+}
+
+// BytesReceived indicates whether any bytes have been received on this stream.
+func (s *Stream) BytesReceived() bool {
+	s.mu.Lock()
+	br := s.bytesReceived
+	s.mu.Unlock()
+	return br
+}
+
 // GoString is implemented by Stream so context.String() won't
 // race when printing %#v.
 func (s *Stream) GoString() string {
@@ -367,19 +459,22 @@ type transportState int
 
 const (
 	reachable transportState = iota
-	unreachable
 	closing
 	draining
 )
 
 // ServerConfig consists of all the configurations to establish a server transport.
 type ServerConfig struct {
-	MaxStreams      uint32
-	AuthInfo        credentials.AuthInfo
-	InTapHandle     tap.ServerInHandle
-	StatsHandler    stats.Handler
-	KeepaliveParams keepalive.ServerParameters
-	KeepalivePolicy keepalive.EnforcementPolicy
+	MaxStreams            uint32
+	AuthInfo              credentials.AuthInfo
+	InTapHandle           tap.ServerInHandle
+	StatsHandler          stats.Handler
+	KeepaliveParams       keepalive.ServerParameters
+	KeepalivePolicy       keepalive.EnforcementPolicy
+	InitialWindowSize     int32
+	InitialConnWindowSize int32
+	WriteBufferSize       int
+	ReadBufferSize        int
 }
 
 // NewServerTransport creates a ServerTransport with conn or non-nil error
@@ -407,6 +502,14 @@ type ConnectOptions struct {
 	KeepaliveParams keepalive.ClientParameters
 	// StatsHandler stores the handler for stats.
 	StatsHandler stats.Handler
+	// InitialWindowSize sets the initial window size for a stream.
+	InitialWindowSize int32
+	// InitialConnWindowSize sets the initial window size for a connection.
+	InitialConnWindowSize int32
+	// WriteBufferSize sets the size of write buffer which in turn determines how much data can be batched before it's written on the wire.
+	WriteBufferSize int
+	// ReadBufferSize sets the size of read buffer, which in turn determines how much data can be read at most for one read syscall.
+	ReadBufferSize int
 }
 
 // TargetInfo contains the information of the target such as network address and metadata.
@@ -417,8 +520,8 @@ type TargetInfo struct {
 
 // NewClientTransport establishes the transport with the required ConnectOptions
 // and returns it to the caller.
-func NewClientTransport(ctx context.Context, target TargetInfo, opts ConnectOptions) (ClientTransport, error) {
-	return newHTTP2Client(ctx, target, opts)
+func NewClientTransport(ctx context.Context, target TargetInfo, opts ConnectOptions, timeout time.Duration) (ClientTransport, error) {
+	return newHTTP2Client(ctx, target, opts, timeout)
 }
 
 // Options provides additional hints and information for message
@@ -430,7 +533,7 @@ type Options struct {
 
 	// Delay is a hint to the transport implementation for whether
 	// the data could be buffered for a batching write. The
-	// Transport implementation may ignore the hint.
+	// transport implementation may ignore the hint.
 	Delay bool
 }
 
@@ -450,10 +553,15 @@ type CallHdr struct {
 	// outbound message.
 	SendCompress string
 
+	// Creds specifies credentials.PerRPCCredentials for a call.
+	Creds credentials.PerRPCCredentials
+
 	// Flush indicates whether a new stream command should be sent
 	// to the peer without waiting for the first data. This is
-	// only a hint. The transport may modify the flush decision
+	// only a hint.
+	// If it's true, the transport may modify the flush decision
 	// for performance purposes.
+	// If it's false, new stream will never be flushed.
 	Flush bool
 }
 
@@ -471,7 +579,7 @@ 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, data []byte, opts *Options) error
+	Write(s *Stream, hdr []byte, data []byte, opts *Options) error
 
 	// NewStream creates a Stream for an RPC.
 	NewStream(ctx context.Context, callHdr *CallHdr) (*Stream, error)
@@ -489,10 +597,13 @@ type ClientTransport interface {
 	// once the transport is initiated.
 	Error() <-chan struct{}
 
-	// GoAway returns a channel that is closed when ClientTranspor
+	// GoAway returns a channel that is closed when ClientTransport
 	// receives the draining signal from the server (e.g., GOAWAY frame in
 	// HTTP/2).
 	GoAway() <-chan struct{}
+
+	// GetGoAwayReason returns the reason why GoAway frame was received.
+	GetGoAwayReason() GoAwayReason
 }
 
 // ServerTransport is the common interface for all gRPC server-side transport
@@ -510,7 +621,7 @@ type ServerTransport interface {
 
 	// Write sends the data for the given stream.
 	// Write may not be called on all streams.
-	Write(s *Stream, data []byte, opts *Options) error
+	Write(s *Stream, hdr []byte, data []byte, 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.
@@ -592,41 +703,80 @@ func (e StreamError) Error() string {
 	return fmt.Sprintf("stream error: code = %s desc = %q", e.Code, e.Desc)
 }
 
+// wait blocks until it can receive from one of the provided contexts or
+// channels.  ctx is the context of the RPC, tctx is the context of the
+// transport, done is a channel closed to indicate the end of the RPC, goAway
+// is a channel closed to indicate a GOAWAY was received, and proceed is a
+// quota channel, whose received value is returned from this function if none
+// of the other signals occur first.
+func wait(ctx, tctx context.Context, done, goAway <-chan struct{}, proceed <-chan int) (int, error) {
+	select {
+	case <-ctx.Done():
+		return 0, ContextErr(ctx.Err())
+	case <-done:
+		return 0, io.EOF
+	case <-goAway:
+		return 0, ErrStreamDrain
+	case <-tctx.Done():
+		return 0, ErrConnClosing
+	case i := <-proceed:
+		return i, nil
+	}
+}
+
 // ContextErr converts the error from context package into a StreamError.
 func ContextErr(err error) StreamError {
 	switch err {
-	case context.DeadlineExceeded:
+	case context.DeadlineExceeded, stdctx.DeadlineExceeded:
 		return streamErrorf(codes.DeadlineExceeded, "%v", err)
-	case context.Canceled:
+	case context.Canceled, stdctx.Canceled:
 		return streamErrorf(codes.Canceled, "%v", err)
 	}
-	panic(fmt.Sprintf("Unexpected error from context packet: %v", err))
+	return streamErrorf(codes.Internal, "Unexpected error from context packet: %v", err)
 }
 
-// wait blocks until it can receive from ctx.Done, closing, or proceed.
-// If it receives from ctx.Done, it returns 0, the StreamError for ctx.Err.
-// If it receives from done, it returns 0, io.EOF if ctx is not done; otherwise
-// it return the StreamError for ctx.Err.
-// If it receives from goAway, it returns 0, ErrStreamDrain.
-// If it receives from closing, it returns 0, ErrConnClosing.
-// If it receives from proceed, it returns the received integer, nil.
-func wait(ctx context.Context, done, goAway, closing <-chan struct{}, proceed <-chan int) (int, error) {
-	select {
-	case <-ctx.Done():
-		return 0, ContextErr(ctx.Err())
-	case <-done:
-		// User cancellation has precedence.
+// GoAwayReason contains the reason for the GoAway frame received.
+type GoAwayReason uint8
+
+const (
+	// Invalid indicates that no GoAway frame is received.
+	Invalid GoAwayReason = 0
+	// NoReason is the default value when GoAway frame is received.
+	NoReason GoAwayReason = 1
+	// TooManyPings indicates that a GoAway frame with ErrCodeEnhanceYourCalm
+	// was received and that the debug data said "too_many_pings".
+	TooManyPings GoAwayReason = 2
+)
+
+// loopyWriter is run in a separate go routine. It is the single code path that will
+// write data on wire.
+func loopyWriter(ctx context.Context, cbuf *controlBuffer, handler func(item) error) {
+	for {
 		select {
+		case i := <-cbuf.get():
+			cbuf.load()
+			if err := handler(i); err != nil {
+				return
+			}
 		case <-ctx.Done():
-			return 0, ContextErr(ctx.Err())
-		default:
+			return
+		}
+	hasData:
+		for {
+			select {
+			case i := <-cbuf.get():
+				cbuf.load()
+				if err := handler(i); err != nil {
+					return
+				}
+			case <-ctx.Done():
+				return
+			default:
+				if err := handler(&flushIO{}); err != nil {
+					return
+				}
+				break hasData
+			}
 		}
-		return 0, io.EOF
-	case <-goAway:
-		return 0, ErrStreamDrain
-	case <-closing:
-		return 0, ErrConnClosing
-	case i := <-proceed:
-		return i, nil
 	}
 }