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/*
*
* Copyright 2014 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
// Package transport defines and implements message oriented communication
// channel to complete various transactions (e.g., an RPC).
package transport // import "google.golang.org/grpc/transport"
import (
"fmt"
"io"
"net"
"sync"
"golang.org/x/net/context"
"golang.org/x/net/http2"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/keepalive"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/stats"
"google.golang.org/grpc/status"
"google.golang.org/grpc/tap"
)
// recvMsg represents the received msg from the transport. All transport
// protocol specific info has been removed.
type recvMsg struct {
data []byte
// nil: received some data
// io.EOF: stream is completed. data is nil.
// other non-nil error: transport failure. data is nil.
err error
}
// 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 recvMsg
mu sync.Mutex
backlog []recvMsg
}
func newRecvBuffer() *recvBuffer {
b := &recvBuffer{
c: make(chan recvMsg, 1),
}
return b
}
func (b *recvBuffer) put(r recvMsg) {
b.mu.Lock()
defer b.mu.Unlock()
if len(b.backlog) == 0 {
select {
case b.c <- r:
return
default:
}
}
b.backlog = append(b.backlog, r)
}
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:
}
}
}
// get returns the channel that receives a recvMsg in the buffer.
//
// 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
}
// recvBufferReader implements io.Reader interface to read the data from
// recvBuffer.
type recvBufferReader struct {
ctx context.Context
goAway chan struct{}
recv *recvBuffer
last []byte // Stores the remaining data in the previous calls.
err error
}
// Read reads the next len(p) bytes from last. If last is drained, it tries to
// read additional data from recv. It blocks if there no additional data available
// in recv. If Read returns any non-nil error, it will continue to return that error.
func (r *recvBufferReader) Read(p []byte) (n int, err error) {
if r.err != nil {
return 0, r.err
}
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.
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 m := <-r.recv.get():
r.recv.load()
if m.err != nil {
return 0, m.err
}
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()
defer b.mu.Unlock()
if len(b.backlog) == 0 {
select {
case b.c <- r:
return
default:
}
}
b.backlog = append(b.backlog, r)
}
func (b *controlBuffer) load() {
b.mu.Lock()
defer b.mu.Unlock()
if len(b.backlog) > 0 {
select {
case b.c <- b.backlog[0]:
b.backlog[0] = nil
b.backlog = b.backlog[1:]
default:
}
}
}
// 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 (
streamActive streamState = iota
streamWriteDone // EndStream sent
streamReadDone // EndStream received
streamDone // the entire stream is finished.
)
// Stream represents an RPC in the transport layer.
type Stream struct {
id uint32
// nil for client side Stream.
st ServerTransport
// ctx is the associated context of the stream.
ctx context.Context
// cancel is always nil for client side Stream.
cancel context.CancelFunc
// done is closed when the final status arrives.
done chan struct{}
// goAway is closed when the server sent GoAways signal before this stream was initiated.
goAway chan struct{}
// method records the associated RPC method of the stream.
method string
recvCompress string
sendCompress string
buf *recvBuffer
trReader io.Reader
fc *inFlow
recvQuota uint32
// TODO: Remote this unused variable.
// The accumulated inbound quota pending for window update.
updateQuota uint32
// 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.
header metadata.MD
// The key-value map of trailer metadata.
trailer metadata.MD
mu sync.RWMutex // guard the following
// headerOK becomes true from the first header is about to send.
headerOk bool
state streamState
// true iff headerChan is closed. Used to avoid closing headerChan
// multiple times.
headerDone bool
// the status error received from the server.
status *status.Status
// rstStream indicates whether a RST_STREAM frame needs to be sent
// to the server to signify that this stream is closing.
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
// message. It is empty string if there is no compression applied.
func (s *Stream) RecvCompress() string {
return s.recvCompress
}
// SetSendCompress sets the compression algorithm to the stream.
func (s *Stream) SetSendCompress(str string) {
s.sendCompress = str
}
// Done returns a chanel which is closed when it receives the final status
// from the server.
func (s *Stream) Done() <-chan struct{} {
return s.done
}
// GoAway returns a channel which is closed when the server sent GoAways signal
// before this stream was initiated.
func (s *Stream) GoAway() <-chan struct{} {
return s.goAway
}
// 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 canceled/expired.
func (s *Stream) Header() (metadata.MD, error) {
var err error
select {
case <-s.ctx.Done():
err = ContextErr(s.ctx.Err())
case <-s.goAway:
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
// after the entire stream is done, it could return an empty MD. Client
// side only.
func (s *Stream) Trailer() metadata.MD {
s.mu.RLock()
defer s.mu.RUnlock()
return s.trailer.Copy()
}
// ServerTransport returns the underlying ServerTransport for the stream.
// The client side stream always returns nil.
func (s *Stream) ServerTransport() ServerTransport {
return s.st
}
// Context returns the context of the stream.
func (s *Stream) Context() context.Context {
return s.ctx
}
// Method returns the method for the stream.
func (s *Stream) Method() string {
return s.method
}
// Status returns the status received from the server.
func (s *Stream) Status() *status.Status {
return s.status
}
// SetHeader sets the header metadata. This can be called multiple times.
// Server side only.
func (s *Stream) SetHeader(md metadata.MD) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.headerOk || s.state == streamDone {
return ErrIllegalHeaderWrite
}
if md.Len() == 0 {
return nil
}
s.header = metadata.Join(s.header, md)
return nil
}
// SetTrailer sets the trailer metadata which will be sent with the RPC status
// by the server. This can be called multiple times. Server side only.
func (s *Stream) SetTrailer(md metadata.MD) error {
if md.Len() == 0 {
return nil
}
s.mu.Lock()
defer s.mu.Unlock()
s.trailer = metadata.Join(s.trailer, md)
return nil
}
func (s *Stream) write(m recvMsg) {
s.buf.put(m)
}
// Read reads all p bytes from the wire for this stream.
func (s *Stream) Read(p []byte) (n int, err error) {
// 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.
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
}
t.windowHandler(n)
return
}
// finish sets the stream's state and status, and closes the done channel.
// s.mu must be held by the caller. st must always be non-nil.
func (s *Stream) finish(st *status.Status) {
s.status = st
s.state = streamDone
close(s.done)
}
// BytesSent indicates whether any bytes have been sent on this stream.
func (s *Stream) BytesSent() bool {
s.mu.Lock()
defer s.mu.Unlock()
return s.bytesSent
}
// BytesReceived indicates whether any bytes have been received on this stream.
func (s *Stream) BytesReceived() bool {
s.mu.Lock()
defer s.mu.Unlock()
return s.bytesReceived
}
// GoString is implemented by Stream so context.String() won't
// race when printing %#v.
func (s *Stream) GoString() string {
return fmt.Sprintf("<stream: %p, %v>", s, s.method)
}
// The key to save transport.Stream in the context.
type streamKey struct{}
// newContextWithStream creates a new context from ctx and attaches stream
// to it.
func newContextWithStream(ctx context.Context, stream *Stream) context.Context {
return context.WithValue(ctx, streamKey{}, stream)
}
// StreamFromContext returns the stream saved in ctx.
func StreamFromContext(ctx context.Context) (s *Stream, ok bool) {
s, ok = ctx.Value(streamKey{}).(*Stream)
return
}
// state of transport
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
InitialWindowSize int32
InitialConnWindowSize int32
}
// NewServerTransport creates a ServerTransport with conn or non-nil error
// if it fails.
func NewServerTransport(protocol string, conn net.Conn, config *ServerConfig) (ServerTransport, error) {
return newHTTP2Server(conn, config)
}
// ConnectOptions covers all relevant options for communicating with the server.
type ConnectOptions struct {
// UserAgent is the application user agent.
UserAgent string
// Authority is the :authority pseudo-header to use. This field has no effect if
// TransportCredentials is set.
Authority string
// Dialer specifies how to dial a network address.
Dialer func(context.Context, string) (net.Conn, error)
// FailOnNonTempDialError specifies if gRPC fails on non-temporary dial errors.
FailOnNonTempDialError bool
// PerRPCCredentials stores the PerRPCCredentials required to issue RPCs.
PerRPCCredentials []credentials.PerRPCCredentials
// TransportCredentials stores the Authenticator required to setup a client connection.
TransportCredentials credentials.TransportCredentials
// KeepaliveParams stores the keepalive parameters.
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
}
// TargetInfo contains the information of the target such as network address and metadata.
type TargetInfo struct {
Addr string
Metadata interface{}
}
// 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)
}
// Options provides additional hints and information for message
// transmission.
type Options struct {
// Last indicates whether this write is the last piece for
// this stream.
Last bool
// 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.
Delay bool
}
// CallHdr carries the information of a particular RPC.
type CallHdr struct {
// Host specifies the peer's host.
Host string
// Method specifies the operation to perform.
Method string
// RecvCompress specifies the compression algorithm applied on
// inbound messages.
RecvCompress string
// SendCompress specifies the compression algorithm applied on
// 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.
// 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
}
// ClientTransport is the common interface for all gRPC client-side transport
// implementations.
type ClientTransport interface {
// Close tears down this transport. Once it returns, the transport
// should not be accessed any more. The caller must make sure this
// is called only once.
Close() error
// GracefulClose starts to tear down the transport. It stops accepting
// new RPCs and wait the completion of the pending RPCs.
GracefulClose() error
// Write sends the data for the given stream. A nil stream indicates
// the write is to be performed on the transport as a whole.
Write(s *Stream, hdr []byte, data []byte, opts *Options) error
// NewStream creates a Stream for an RPC.
NewStream(ctx context.Context, callHdr *CallHdr) (*Stream, error)
// CloseStream clears the footprint of a stream when the stream is
// not needed any more. The err indicates the error incurred when
// CloseStream is called. Must be called when a stream is finished
// unless the associated transport is closing.
CloseStream(stream *Stream, err error)
// Error returns a channel that is closed when some I/O error
// happens. Typically the caller should have a goroutine to monitor
// this in order to take action (e.g., close the current transport
// and create a new one) in error case. It should not return nil
// once the transport is initiated.
Error() <-chan struct{}
// 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
// implementations.
//
// Methods may be called concurrently from multiple goroutines, but
// Write methods for a given Stream will be called serially.
type ServerTransport interface {
// HandleStreams receives incoming streams using the given handler.
HandleStreams(func(*Stream), func(context.Context, string) context.Context)
// WriteHeader sends the header metadata for the given stream.
// WriteHeader may not be called on all streams.
WriteHeader(s *Stream, md metadata.MD) error
// Write sends the data for the given stream.
// Write may not be called on all streams.
Write(s *Stream, hdr []byte, data []byte, opts *Options) error
// WriteStatus sends the status of a stream to the client. WriteStatus is
// the final call made on a stream and always occurs.
WriteStatus(s *Stream, st *status.Status) error
// Close tears down the transport. Once it is called, the transport
// should not be accessed any more. All the pending streams and their
// handlers will be terminated asynchronously.
Close() error
// RemoteAddr returns the remote network address.
RemoteAddr() net.Addr
// Drain notifies the client this ServerTransport stops accepting new RPCs.
Drain()
}
// streamErrorf creates an StreamError with the specified error code and description.
func streamErrorf(c codes.Code, format string, a ...interface{}) StreamError {
return StreamError{
Code: c,
Desc: fmt.Sprintf(format, a...),
}
}
// connectionErrorf creates an ConnectionError with the specified error description.
func connectionErrorf(temp bool, e error, format string, a ...interface{}) ConnectionError {
return ConnectionError{
Desc: fmt.Sprintf(format, a...),
temp: temp,
err: e,
}
}
// ConnectionError is an error that results in the termination of the
// entire connection and the retry of all the active streams.
type ConnectionError struct {
Desc string
temp bool
err error
}
func (e ConnectionError) Error() string {
return fmt.Sprintf("connection error: desc = %q", e.Desc)
}
// Temporary indicates if this connection error is temporary or fatal.
func (e ConnectionError) Temporary() bool {
return e.temp
}
// Origin returns the original error of this connection error.
func (e ConnectionError) Origin() error {
// Never return nil error here.
// If the original error is nil, return itself.
if e.err == nil {
return e
}
return e.err
}
var (
// ErrConnClosing indicates that the transport is closing.
ErrConnClosing = connectionErrorf(true, nil, "transport is closing")
// ErrStreamDrain indicates that the stream is rejected by the server because
// the server stops accepting new RPCs.
ErrStreamDrain = streamErrorf(codes.Unavailable, "the server stops accepting new RPCs")
)
// TODO: See if we can replace StreamError with status package errors.
// StreamError is an error that only affects one stream within a connection.
type StreamError struct {
Code codes.Code
Desc string
}
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 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:
return 0, io.EOF
case <-goAway:
return 0, ErrStreamDrain
case <-closing:
return 0, ErrConnClosing
case i := <-proceed:
return i, nil
}
}
// 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(cbuf *controlBuffer, done chan struct{}, handler func(item) error) {
for {
select {
case i := <-cbuf.get():
cbuf.load()
if err := handler(i); err != nil {
return
}
case <-done:
return
}
hasData:
for {
select {
case i := <-cbuf.get():
cbuf.load()
if err := handler(i); err != nil {
return
}
case <-done:
return
default:
if err := handler(&flushIO{}); err != nil {
return
}
break hasData
}
}
}
}