diff --git a/vendor/google.golang.org/grpc/rpc_util.go b/vendor/google.golang.org/grpc/rpc_util.go
new file mode 100644
index 0000000..088c3f1
--- /dev/null
+++ b/vendor/google.golang.org/grpc/rpc_util.go
@@ -0,0 +1,863 @@
+/*
+ *
+ * Copyright 2014 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+	"bytes"
+	"compress/gzip"
+	"context"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"math"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/encoding"
+	"google.golang.org/grpc/encoding/proto"
+	"google.golang.org/grpc/internal/transport"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/peer"
+	"google.golang.org/grpc/stats"
+	"google.golang.org/grpc/status"
+)
+
+// Compressor defines the interface gRPC uses to compress a message.
+//
+// Deprecated: use package encoding.
+type Compressor interface {
+	// Do compresses p into w.
+	Do(w io.Writer, p []byte) error
+	// Type returns the compression algorithm the Compressor uses.
+	Type() string
+}
+
+type gzipCompressor struct {
+	pool sync.Pool
+}
+
+// NewGZIPCompressor creates a Compressor based on GZIP.
+//
+// Deprecated: use package encoding/gzip.
+func NewGZIPCompressor() Compressor {
+	c, _ := NewGZIPCompressorWithLevel(gzip.DefaultCompression)
+	return c
+}
+
+// NewGZIPCompressorWithLevel is like NewGZIPCompressor but specifies the gzip compression level instead
+// of assuming DefaultCompression.
+//
+// The error returned will be nil if the level is valid.
+//
+// Deprecated: use package encoding/gzip.
+func NewGZIPCompressorWithLevel(level int) (Compressor, error) {
+	if level < gzip.DefaultCompression || level > gzip.BestCompression {
+		return nil, fmt.Errorf("grpc: invalid compression level: %d", level)
+	}
+	return &gzipCompressor{
+		pool: sync.Pool{
+			New: func() interface{} {
+				w, err := gzip.NewWriterLevel(ioutil.Discard, level)
+				if err != nil {
+					panic(err)
+				}
+				return w
+			},
+		},
+	}, nil
+}
+
+func (c *gzipCompressor) Do(w io.Writer, p []byte) error {
+	z := c.pool.Get().(*gzip.Writer)
+	defer c.pool.Put(z)
+	z.Reset(w)
+	if _, err := z.Write(p); err != nil {
+		return err
+	}
+	return z.Close()
+}
+
+func (c *gzipCompressor) Type() string {
+	return "gzip"
+}
+
+// Decompressor defines the interface gRPC uses to decompress a message.
+//
+// Deprecated: use package encoding.
+type Decompressor interface {
+	// Do reads the data from r and uncompress them.
+	Do(r io.Reader) ([]byte, error)
+	// Type returns the compression algorithm the Decompressor uses.
+	Type() string
+}
+
+type gzipDecompressor struct {
+	pool sync.Pool
+}
+
+// NewGZIPDecompressor creates a Decompressor based on GZIP.
+//
+// Deprecated: use package encoding/gzip.
+func NewGZIPDecompressor() Decompressor {
+	return &gzipDecompressor{}
+}
+
+func (d *gzipDecompressor) Do(r io.Reader) ([]byte, error) {
+	var z *gzip.Reader
+	switch maybeZ := d.pool.Get().(type) {
+	case nil:
+		newZ, err := gzip.NewReader(r)
+		if err != nil {
+			return nil, err
+		}
+		z = newZ
+	case *gzip.Reader:
+		z = maybeZ
+		if err := z.Reset(r); err != nil {
+			d.pool.Put(z)
+			return nil, err
+		}
+	}
+
+	defer func() {
+		z.Close()
+		d.pool.Put(z)
+	}()
+	return ioutil.ReadAll(z)
+}
+
+func (d *gzipDecompressor) Type() string {
+	return "gzip"
+}
+
+// callInfo contains all related configuration and information about an RPC.
+type callInfo struct {
+	compressorType        string
+	failFast              bool
+	stream                ClientStream
+	maxReceiveMessageSize *int
+	maxSendMessageSize    *int
+	creds                 credentials.PerRPCCredentials
+	contentSubtype        string
+	codec                 baseCodec
+	maxRetryRPCBufferSize int
+}
+
+func defaultCallInfo() *callInfo {
+	return &callInfo{
+		failFast:              true,
+		maxRetryRPCBufferSize: 256 * 1024, // 256KB
+	}
+}
+
+// CallOption configures a Call before it starts or extracts information from
+// a Call after it completes.
+type CallOption interface {
+	// before is called before the call is sent to any server.  If before
+	// returns a non-nil error, the RPC fails with that error.
+	before(*callInfo) error
+
+	// after is called after the call has completed.  after cannot return an
+	// error, so any failures should be reported via output parameters.
+	after(*callInfo)
+}
+
+// EmptyCallOption does not alter the Call configuration.
+// It can be embedded in another structure to carry satellite data for use
+// by interceptors.
+type EmptyCallOption struct{}
+
+func (EmptyCallOption) before(*callInfo) error { return nil }
+func (EmptyCallOption) after(*callInfo)        {}
+
+// Header returns a CallOptions that retrieves the header metadata
+// for a unary RPC.
+func Header(md *metadata.MD) CallOption {
+	return HeaderCallOption{HeaderAddr: md}
+}
+
+// HeaderCallOption is a CallOption for collecting response header metadata.
+// The metadata field will be populated *after* the RPC completes.
+// This is an EXPERIMENTAL API.
+type HeaderCallOption struct {
+	HeaderAddr *metadata.MD
+}
+
+func (o HeaderCallOption) before(c *callInfo) error { return nil }
+func (o HeaderCallOption) after(c *callInfo) {
+	if c.stream != nil {
+		*o.HeaderAddr, _ = c.stream.Header()
+	}
+}
+
+// Trailer returns a CallOptions that retrieves the trailer metadata
+// for a unary RPC.
+func Trailer(md *metadata.MD) CallOption {
+	return TrailerCallOption{TrailerAddr: md}
+}
+
+// TrailerCallOption is a CallOption for collecting response trailer metadata.
+// The metadata field will be populated *after* the RPC completes.
+// This is an EXPERIMENTAL API.
+type TrailerCallOption struct {
+	TrailerAddr *metadata.MD
+}
+
+func (o TrailerCallOption) before(c *callInfo) error { return nil }
+func (o TrailerCallOption) after(c *callInfo) {
+	if c.stream != nil {
+		*o.TrailerAddr = c.stream.Trailer()
+	}
+}
+
+// Peer returns a CallOption that retrieves peer information for a unary RPC.
+// The peer field will be populated *after* the RPC completes.
+func Peer(p *peer.Peer) CallOption {
+	return PeerCallOption{PeerAddr: p}
+}
+
+// PeerCallOption is a CallOption for collecting the identity of the remote
+// peer. The peer field will be populated *after* the RPC completes.
+// This is an EXPERIMENTAL API.
+type PeerCallOption struct {
+	PeerAddr *peer.Peer
+}
+
+func (o PeerCallOption) before(c *callInfo) error { return nil }
+func (o PeerCallOption) after(c *callInfo) {
+	if c.stream != nil {
+		if x, ok := peer.FromContext(c.stream.Context()); ok {
+			*o.PeerAddr = *x
+		}
+	}
+}
+
+// WaitForReady configures the action to take when an RPC is attempted on broken
+// connections or unreachable servers. If waitForReady is false, the RPC will fail
+// immediately. Otherwise, the RPC client will block the call until a
+// connection is available (or the call is canceled or times out) and will
+// retry the call if it fails due to a transient error.  gRPC will not retry if
+// data was written to the wire unless the server indicates it did not process
+// the data.  Please refer to
+// https://github.com/grpc/grpc/blob/master/doc/wait-for-ready.md.
+//
+// By default, RPCs don't "wait for ready".
+func WaitForReady(waitForReady bool) CallOption {
+	return FailFastCallOption{FailFast: !waitForReady}
+}
+
+// FailFast is the opposite of WaitForReady.
+//
+// Deprecated: use WaitForReady.
+func FailFast(failFast bool) CallOption {
+	return FailFastCallOption{FailFast: failFast}
+}
+
+// FailFastCallOption is a CallOption for indicating whether an RPC should fail
+// fast or not.
+// This is an EXPERIMENTAL API.
+type FailFastCallOption struct {
+	FailFast bool
+}
+
+func (o FailFastCallOption) before(c *callInfo) error {
+	c.failFast = o.FailFast
+	return nil
+}
+func (o FailFastCallOption) after(c *callInfo) {}
+
+// MaxCallRecvMsgSize returns a CallOption which sets the maximum message size the client can receive.
+func MaxCallRecvMsgSize(s int) CallOption {
+	return MaxRecvMsgSizeCallOption{MaxRecvMsgSize: s}
+}
+
+// MaxRecvMsgSizeCallOption is a CallOption that indicates the maximum message
+// size the client can receive.
+// This is an EXPERIMENTAL API.
+type MaxRecvMsgSizeCallOption struct {
+	MaxRecvMsgSize int
+}
+
+func (o MaxRecvMsgSizeCallOption) before(c *callInfo) error {
+	c.maxReceiveMessageSize = &o.MaxRecvMsgSize
+	return nil
+}
+func (o MaxRecvMsgSizeCallOption) after(c *callInfo) {}
+
+// MaxCallSendMsgSize returns a CallOption which sets the maximum message size the client can send.
+func MaxCallSendMsgSize(s int) CallOption {
+	return MaxSendMsgSizeCallOption{MaxSendMsgSize: s}
+}
+
+// MaxSendMsgSizeCallOption is a CallOption that indicates the maximum message
+// size the client can send.
+// This is an EXPERIMENTAL API.
+type MaxSendMsgSizeCallOption struct {
+	MaxSendMsgSize int
+}
+
+func (o MaxSendMsgSizeCallOption) before(c *callInfo) error {
+	c.maxSendMessageSize = &o.MaxSendMsgSize
+	return nil
+}
+func (o MaxSendMsgSizeCallOption) after(c *callInfo) {}
+
+// PerRPCCredentials returns a CallOption that sets credentials.PerRPCCredentials
+// for a call.
+func PerRPCCredentials(creds credentials.PerRPCCredentials) CallOption {
+	return PerRPCCredsCallOption{Creds: creds}
+}
+
+// PerRPCCredsCallOption is a CallOption that indicates the per-RPC
+// credentials to use for the call.
+// This is an EXPERIMENTAL API.
+type PerRPCCredsCallOption struct {
+	Creds credentials.PerRPCCredentials
+}
+
+func (o PerRPCCredsCallOption) before(c *callInfo) error {
+	c.creds = o.Creds
+	return nil
+}
+func (o PerRPCCredsCallOption) after(c *callInfo) {}
+
+// UseCompressor returns a CallOption which sets the compressor used when
+// sending the request.  If WithCompressor is also set, UseCompressor has
+// higher priority.
+//
+// This API is EXPERIMENTAL.
+func UseCompressor(name string) CallOption {
+	return CompressorCallOption{CompressorType: name}
+}
+
+// CompressorCallOption is a CallOption that indicates the compressor to use.
+// This is an EXPERIMENTAL API.
+type CompressorCallOption struct {
+	CompressorType string
+}
+
+func (o CompressorCallOption) before(c *callInfo) error {
+	c.compressorType = o.CompressorType
+	return nil
+}
+func (o CompressorCallOption) after(c *callInfo) {}
+
+// CallContentSubtype returns a CallOption that will set the content-subtype
+// for a call. For example, if content-subtype is "json", the Content-Type over
+// the wire will be "application/grpc+json". The content-subtype is converted
+// to lowercase before being included in Content-Type. See Content-Type on
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
+// more details.
+//
+// If ForceCodec is not also used, the content-subtype will be used to look up
+// the Codec to use in the registry controlled by RegisterCodec. See the
+// documentation on RegisterCodec for details on registration. The lookup of
+// content-subtype is case-insensitive. If no such Codec is found, the call
+// will result in an error with code codes.Internal.
+//
+// If ForceCodec is also used, that Codec will be used for all request and
+// response messages, with the content-subtype set to the given contentSubtype
+// here for requests.
+func CallContentSubtype(contentSubtype string) CallOption {
+	return ContentSubtypeCallOption{ContentSubtype: strings.ToLower(contentSubtype)}
+}
+
+// ContentSubtypeCallOption is a CallOption that indicates the content-subtype
+// used for marshaling messages.
+// This is an EXPERIMENTAL API.
+type ContentSubtypeCallOption struct {
+	ContentSubtype string
+}
+
+func (o ContentSubtypeCallOption) before(c *callInfo) error {
+	c.contentSubtype = o.ContentSubtype
+	return nil
+}
+func (o ContentSubtypeCallOption) after(c *callInfo) {}
+
+// ForceCodec returns a CallOption that will set the given Codec to be
+// used for all request and response messages for a call. The result of calling
+// String() will be used as the content-subtype in a case-insensitive manner.
+//
+// See Content-Type on
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
+// more details. Also see the documentation on RegisterCodec and
+// CallContentSubtype for more details on the interaction between Codec and
+// content-subtype.
+//
+// This function is provided for advanced users; prefer to use only
+// CallContentSubtype to select a registered codec instead.
+//
+// This is an EXPERIMENTAL API.
+func ForceCodec(codec encoding.Codec) CallOption {
+	return ForceCodecCallOption{Codec: codec}
+}
+
+// ForceCodecCallOption is a CallOption that indicates the codec used for
+// marshaling messages.
+//
+// This is an EXPERIMENTAL API.
+type ForceCodecCallOption struct {
+	Codec encoding.Codec
+}
+
+func (o ForceCodecCallOption) before(c *callInfo) error {
+	c.codec = o.Codec
+	return nil
+}
+func (o ForceCodecCallOption) after(c *callInfo) {}
+
+// CallCustomCodec behaves like ForceCodec, but accepts a grpc.Codec instead of
+// an encoding.Codec.
+//
+// Deprecated: use ForceCodec instead.
+func CallCustomCodec(codec Codec) CallOption {
+	return CustomCodecCallOption{Codec: codec}
+}
+
+// CustomCodecCallOption is a CallOption that indicates the codec used for
+// marshaling messages.
+//
+// This is an EXPERIMENTAL API.
+type CustomCodecCallOption struct {
+	Codec Codec
+}
+
+func (o CustomCodecCallOption) before(c *callInfo) error {
+	c.codec = o.Codec
+	return nil
+}
+func (o CustomCodecCallOption) after(c *callInfo) {}
+
+// MaxRetryRPCBufferSize returns a CallOption that limits the amount of memory
+// used for buffering this RPC's requests for retry purposes.
+//
+// This API is EXPERIMENTAL.
+func MaxRetryRPCBufferSize(bytes int) CallOption {
+	return MaxRetryRPCBufferSizeCallOption{bytes}
+}
+
+// MaxRetryRPCBufferSizeCallOption is a CallOption indicating the amount of
+// memory to be used for caching this RPC for retry purposes.
+// This is an EXPERIMENTAL API.
+type MaxRetryRPCBufferSizeCallOption struct {
+	MaxRetryRPCBufferSize int
+}
+
+func (o MaxRetryRPCBufferSizeCallOption) before(c *callInfo) error {
+	c.maxRetryRPCBufferSize = o.MaxRetryRPCBufferSize
+	return nil
+}
+func (o MaxRetryRPCBufferSizeCallOption) after(c *callInfo) {}
+
+// The format of the payload: compressed or not?
+type payloadFormat uint8
+
+const (
+	compressionNone payloadFormat = 0 // no compression
+	compressionMade payloadFormat = 1 // compressed
+)
+
+// parser reads complete gRPC messages from the underlying reader.
+type parser struct {
+	// r is the underlying reader.
+	// See the comment on recvMsg for the permissible
+	// error types.
+	r io.Reader
+
+	// The header of a gRPC message. Find more detail at
+	// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md
+	header [5]byte
+}
+
+// recvMsg reads a complete gRPC message from the stream.
+//
+// It returns the message and its payload (compression/encoding)
+// format. The caller owns the returned msg memory.
+//
+// If there is an error, possible values are:
+//   * io.EOF, when no messages remain
+//   * io.ErrUnexpectedEOF
+//   * of type transport.ConnectionError
+//   * an error from the status package
+// No other error values or types must be returned, which also means
+// that the underlying io.Reader must not return an incompatible
+// error.
+func (p *parser) recvMsg(maxReceiveMessageSize int) (pf payloadFormat, msg []byte, err error) {
+	if _, err := p.r.Read(p.header[:]); err != nil {
+		return 0, nil, err
+	}
+
+	pf = payloadFormat(p.header[0])
+	length := binary.BigEndian.Uint32(p.header[1:])
+
+	if length == 0 {
+		return pf, nil, nil
+	}
+	if int64(length) > int64(maxInt) {
+		return 0, nil, status.Errorf(codes.ResourceExhausted, "grpc: received message larger than max length allowed on current machine (%d vs. %d)", length, maxInt)
+	}
+	if int(length) > maxReceiveMessageSize {
+		return 0, nil, status.Errorf(codes.ResourceExhausted, "grpc: received message larger than max (%d vs. %d)", length, maxReceiveMessageSize)
+	}
+	// TODO(bradfitz,zhaoq): garbage. reuse buffer after proto decoding instead
+	// of making it for each message:
+	msg = make([]byte, int(length))
+	if _, err := p.r.Read(msg); err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
+		}
+		return 0, nil, err
+	}
+	return pf, msg, nil
+}
+
+// encode serializes msg and returns a buffer containing the message, or an
+// error if it is too large to be transmitted by grpc.  If msg is nil, it
+// generates an empty message.
+func encode(c baseCodec, msg interface{}) ([]byte, error) {
+	if msg == nil { // NOTE: typed nils will not be caught by this check
+		return nil, nil
+	}
+	b, err := c.Marshal(msg)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "grpc: error while marshaling: %v", err.Error())
+	}
+	if uint(len(b)) > math.MaxUint32 {
+		return nil, status.Errorf(codes.ResourceExhausted, "grpc: message too large (%d bytes)", len(b))
+	}
+	return b, nil
+}
+
+// compress returns the input bytes compressed by compressor or cp.  If both
+// compressors are nil, returns nil.
+//
+// TODO(dfawley): eliminate cp parameter by wrapping Compressor in an encoding.Compressor.
+func compress(in []byte, cp Compressor, compressor encoding.Compressor) ([]byte, error) {
+	if compressor == nil && cp == nil {
+		return nil, nil
+	}
+	wrapErr := func(err error) error {
+		return status.Errorf(codes.Internal, "grpc: error while compressing: %v", err.Error())
+	}
+	cbuf := &bytes.Buffer{}
+	if compressor != nil {
+		z, err := compressor.Compress(cbuf)
+		if err != nil {
+			return nil, wrapErr(err)
+		}
+		if _, err := z.Write(in); err != nil {
+			return nil, wrapErr(err)
+		}
+		if err := z.Close(); err != nil {
+			return nil, wrapErr(err)
+		}
+	} else {
+		if err := cp.Do(cbuf, in); err != nil {
+			return nil, wrapErr(err)
+		}
+	}
+	return cbuf.Bytes(), nil
+}
+
+const (
+	payloadLen = 1
+	sizeLen    = 4
+	headerLen  = payloadLen + sizeLen
+)
+
+// msgHeader returns a 5-byte header for the message being transmitted and the
+// payload, which is compData if non-nil or data otherwise.
+func msgHeader(data, compData []byte) (hdr []byte, payload []byte) {
+	hdr = make([]byte, headerLen)
+	if compData != nil {
+		hdr[0] = byte(compressionMade)
+		data = compData
+	} else {
+		hdr[0] = byte(compressionNone)
+	}
+
+	// Write length of payload into buf
+	binary.BigEndian.PutUint32(hdr[payloadLen:], uint32(len(data)))
+	return hdr, data
+}
+
+func outPayload(client bool, msg interface{}, data, payload []byte, t time.Time) *stats.OutPayload {
+	return &stats.OutPayload{
+		Client:     client,
+		Payload:    msg,
+		Data:       data,
+		Length:     len(data),
+		WireLength: len(payload) + headerLen,
+		SentTime:   t,
+	}
+}
+
+func checkRecvPayload(pf payloadFormat, recvCompress string, haveCompressor bool) *status.Status {
+	switch pf {
+	case compressionNone:
+	case compressionMade:
+		if recvCompress == "" || recvCompress == encoding.Identity {
+			return status.New(codes.Internal, "grpc: compressed flag set with identity or empty encoding")
+		}
+		if !haveCompressor {
+			return status.Newf(codes.Unimplemented, "grpc: Decompressor is not installed for grpc-encoding %q", recvCompress)
+		}
+	default:
+		return status.Newf(codes.Internal, "grpc: received unexpected payload format %d", pf)
+	}
+	return nil
+}
+
+type payloadInfo struct {
+	wireLength        int // The compressed length got from wire.
+	uncompressedBytes []byte
+}
+
+func recvAndDecompress(p *parser, s *transport.Stream, dc Decompressor, maxReceiveMessageSize int, payInfo *payloadInfo, compressor encoding.Compressor) ([]byte, error) {
+	pf, d, err := p.recvMsg(maxReceiveMessageSize)
+	if err != nil {
+		return nil, err
+	}
+	if payInfo != nil {
+		payInfo.wireLength = len(d)
+	}
+
+	if st := checkRecvPayload(pf, s.RecvCompress(), compressor != nil || dc != nil); st != nil {
+		return nil, st.Err()
+	}
+
+	if pf == compressionMade {
+		// To match legacy behavior, if the decompressor is set by WithDecompressor or RPCDecompressor,
+		// use this decompressor as the default.
+		if dc != nil {
+			d, err = dc.Do(bytes.NewReader(d))
+			if err != nil {
+				return nil, status.Errorf(codes.Internal, "grpc: failed to decompress the received message %v", err)
+			}
+		} else {
+			dcReader, err := compressor.Decompress(bytes.NewReader(d))
+			if err != nil {
+				return nil, status.Errorf(codes.Internal, "grpc: failed to decompress the received message %v", err)
+			}
+			// Read from LimitReader with limit max+1. So if the underlying
+			// reader is over limit, the result will be bigger than max.
+			d, err = ioutil.ReadAll(io.LimitReader(dcReader, int64(maxReceiveMessageSize)+1))
+			if err != nil {
+				return nil, status.Errorf(codes.Internal, "grpc: failed to decompress the received message %v", err)
+			}
+		}
+	}
+	if len(d) > maxReceiveMessageSize {
+		// TODO: Revisit the error code. Currently keep it consistent with java
+		// implementation.
+		return nil, status.Errorf(codes.ResourceExhausted, "grpc: received message larger than max (%d vs. %d)", len(d), maxReceiveMessageSize)
+	}
+	return d, nil
+}
+
+// For the two compressor parameters, both should not be set, but if they are,
+// dc takes precedence over compressor.
+// TODO(dfawley): wrap the old compressor/decompressor using the new API?
+func recv(p *parser, c baseCodec, s *transport.Stream, dc Decompressor, m interface{}, maxReceiveMessageSize int, payInfo *payloadInfo, compressor encoding.Compressor) error {
+	d, err := recvAndDecompress(p, s, dc, maxReceiveMessageSize, payInfo, compressor)
+	if err != nil {
+		return err
+	}
+	if err := c.Unmarshal(d, m); err != nil {
+		return status.Errorf(codes.Internal, "grpc: failed to unmarshal the received message %v", err)
+	}
+	if payInfo != nil {
+		payInfo.uncompressedBytes = d
+	}
+	return nil
+}
+
+// Information about RPC
+type rpcInfo struct {
+	failfast      bool
+	preloaderInfo *compressorInfo
+}
+
+// Information about Preloader
+// Responsible for storing codec, and compressors
+// If stream (s) has  context s.Context which stores rpcInfo that has non nil
+// pointers to codec, and compressors, then we can use preparedMsg for Async message prep
+// and reuse marshalled bytes
+type compressorInfo struct {
+	codec baseCodec
+	cp    Compressor
+	comp  encoding.Compressor
+}
+
+type rpcInfoContextKey struct{}
+
+func newContextWithRPCInfo(ctx context.Context, failfast bool, codec baseCodec, cp Compressor, comp encoding.Compressor) context.Context {
+	return context.WithValue(ctx, rpcInfoContextKey{}, &rpcInfo{
+		failfast: failfast,
+		preloaderInfo: &compressorInfo{
+			codec: codec,
+			cp:    cp,
+			comp:  comp,
+		},
+	})
+}
+
+func rpcInfoFromContext(ctx context.Context) (s *rpcInfo, ok bool) {
+	s, ok = ctx.Value(rpcInfoContextKey{}).(*rpcInfo)
+	return
+}
+
+// Code returns the error code for err if it was produced by the rpc system.
+// Otherwise, it returns codes.Unknown.
+//
+// Deprecated: use status.Code instead.
+func Code(err error) codes.Code {
+	return status.Code(err)
+}
+
+// ErrorDesc returns the error description of err if it was produced by the rpc system.
+// Otherwise, it returns err.Error() or empty string when err is nil.
+//
+// Deprecated: use status.Convert and Message method instead.
+func ErrorDesc(err error) string {
+	return status.Convert(err).Message()
+}
+
+// Errorf returns an error containing an error code and a description;
+// Errorf returns nil if c is OK.
+//
+// Deprecated: use status.Errorf instead.
+func Errorf(c codes.Code, format string, a ...interface{}) error {
+	return status.Errorf(c, format, a...)
+}
+
+// toRPCErr converts an error into an error from the status package.
+func toRPCErr(err error) error {
+	if err == nil || err == io.EOF {
+		return err
+	}
+	if err == io.ErrUnexpectedEOF {
+		return status.Error(codes.Internal, err.Error())
+	}
+	if _, ok := status.FromError(err); ok {
+		return err
+	}
+	switch e := err.(type) {
+	case transport.ConnectionError:
+		return status.Error(codes.Unavailable, e.Desc)
+	default:
+		switch err {
+		case context.DeadlineExceeded:
+			return status.Error(codes.DeadlineExceeded, err.Error())
+		case context.Canceled:
+			return status.Error(codes.Canceled, err.Error())
+		}
+	}
+	return status.Error(codes.Unknown, err.Error())
+}
+
+// setCallInfoCodec should only be called after CallOptions have been applied.
+func setCallInfoCodec(c *callInfo) error {
+	if c.codec != nil {
+		// codec was already set by a CallOption; use it.
+		return nil
+	}
+
+	if c.contentSubtype == "" {
+		// No codec specified in CallOptions; use proto by default.
+		c.codec = encoding.GetCodec(proto.Name)
+		return nil
+	}
+
+	// c.contentSubtype is already lowercased in CallContentSubtype
+	c.codec = encoding.GetCodec(c.contentSubtype)
+	if c.codec == nil {
+		return status.Errorf(codes.Internal, "no codec registered for content-subtype %s", c.contentSubtype)
+	}
+	return nil
+}
+
+// parseDialTarget returns the network and address to pass to dialer
+func parseDialTarget(target string) (net string, addr string) {
+	net = "tcp"
+
+	m1 := strings.Index(target, ":")
+	m2 := strings.Index(target, ":/")
+
+	// handle unix:addr which will fail with url.Parse
+	if m1 >= 0 && m2 < 0 {
+		if n := target[0:m1]; n == "unix" {
+			net = n
+			addr = target[m1+1:]
+			return net, addr
+		}
+	}
+	if m2 >= 0 {
+		t, err := url.Parse(target)
+		if err != nil {
+			return net, target
+		}
+		scheme := t.Scheme
+		addr = t.Path
+		if scheme == "unix" {
+			net = scheme
+			if addr == "" {
+				addr = t.Host
+			}
+			return net, addr
+		}
+	}
+
+	return net, target
+}
+
+// channelzData is used to store channelz related data for ClientConn, addrConn and Server.
+// These fields cannot be embedded in the original structs (e.g. ClientConn), since to do atomic
+// operation on int64 variable on 32-bit machine, user is responsible to enforce memory alignment.
+// Here, by grouping those int64 fields inside a struct, we are enforcing the alignment.
+type channelzData struct {
+	callsStarted   int64
+	callsFailed    int64
+	callsSucceeded int64
+	// lastCallStartedTime stores the timestamp that last call starts. It is of int64 type instead of
+	// time.Time since it's more costly to atomically update time.Time variable than int64 variable.
+	lastCallStartedTime int64
+}
+
+// The SupportPackageIsVersion variables are referenced from generated protocol
+// buffer files to ensure compatibility with the gRPC version used.  The latest
+// support package version is 5.
+//
+// Older versions are kept for compatibility. They may be removed if
+// compatibility cannot be maintained.
+//
+// These constants should not be referenced from any other code.
+const (
+	SupportPackageIsVersion3 = true
+	SupportPackageIsVersion4 = true
+	SupportPackageIsVersion5 = true
+)
+
+const grpcUA = "grpc-go/" + Version