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stream.go
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stream.go
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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 grpc
import (
"context"
"errors"
"io"
"math"
"strconv"
"sync"
"time"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/encoding"
"google.golang.org/grpc/internal"
"google.golang.org/grpc/internal/balancerload"
"google.golang.org/grpc/internal/binarylog"
"google.golang.org/grpc/internal/channelz"
"google.golang.org/grpc/internal/grpcrand"
"google.golang.org/grpc/internal/grpcutil"
imetadata "google.golang.org/grpc/internal/metadata"
iresolver "google.golang.org/grpc/internal/resolver"
"google.golang.org/grpc/internal/serviceconfig"
istatus "google.golang.org/grpc/internal/status"
"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"
)
var metadataFromOutgoingContextRaw = internal.FromOutgoingContextRaw.(func(context.Context) (metadata.MD, [][]string, bool))
// StreamHandler defines the handler called by gRPC server to complete the
// execution of a streaming RPC.
//
// If a StreamHandler returns an error, it should either be produced by the
// status package, or be one of the context errors. Otherwise, gRPC will use
// codes.Unknown as the status code and err.Error() as the status message of the
// RPC.
type StreamHandler func(srv any, stream ServerStream) error
// StreamDesc represents a streaming RPC service's method specification. Used
// on the server when registering services and on the client when initiating
// new streams.
type StreamDesc struct {
// StreamName and Handler are only used when registering handlers on a
// server.
StreamName string // the name of the method excluding the service
Handler StreamHandler // the handler called for the method
// ServerStreams and ClientStreams are used for registering handlers on a
// server as well as defining RPC behavior when passed to NewClientStream
// and ClientConn.NewStream. At least one must be true.
ServerStreams bool // indicates the server can perform streaming sends
ClientStreams bool // indicates the client can perform streaming sends
}
// Stream defines the common interface a client or server stream has to satisfy.
//
// Deprecated: See ClientStream and ServerStream documentation instead.
type Stream interface {
// Deprecated: See ClientStream and ServerStream documentation instead.
Context() context.Context
// Deprecated: See ClientStream and ServerStream documentation instead.
SendMsg(m any) error
// Deprecated: See ClientStream and ServerStream documentation instead.
RecvMsg(m any) error
}
// ClientStream defines the client-side behavior of a streaming RPC.
//
// All errors returned from ClientStream methods are compatible with the
// status package.
type ClientStream interface {
// Header returns the header metadata received from the server if there
// is any. It blocks if the metadata is not ready to read. If the metadata
// is nil and the error is also nil, then the stream was terminated without
// headers, and the status can be discovered by calling RecvMsg.
Header() (metadata.MD, error)
// Trailer returns the trailer metadata from the server, if there is any.
// It must only be called after stream.CloseAndRecv has returned, or
// stream.Recv has returned a non-nil error (including io.EOF).
Trailer() metadata.MD
// CloseSend closes the send direction of the stream. It closes the stream
// when non-nil error is met. It is also not safe to call CloseSend
// concurrently with SendMsg.
CloseSend() error
// Context returns the context for this stream.
//
// It should not be called until after Header or RecvMsg has returned. Once
// called, subsequent client-side retries are disabled.
Context() context.Context
// SendMsg is generally called by generated code. On error, SendMsg aborts
// the stream. If the error was generated by the client, the status is
// returned directly; otherwise, io.EOF is returned and the status of
// the stream may be discovered using RecvMsg.
//
// SendMsg blocks until:
// - There is sufficient flow control to schedule m with the transport, or
// - The stream is done, or
// - The stream breaks.
//
// SendMsg does not wait until the message is received by the server. An
// untimely stream closure may result in lost messages. To ensure delivery,
// users should ensure the RPC completed successfully using RecvMsg.
//
// It is safe to have a goroutine calling SendMsg and another goroutine
// calling RecvMsg on the same stream at the same time, but it is not safe
// to call SendMsg on the same stream in different goroutines. It is also
// not safe to call CloseSend concurrently with SendMsg.
//
// It is not safe to modify the message after calling SendMsg. Tracing
// libraries and stats handlers may use the message lazily.
SendMsg(m any) error
// RecvMsg blocks until it receives a message into m or the stream is
// done. It returns io.EOF when the stream completes successfully. On
// any other error, the stream is aborted and the error contains the RPC
// status.
//
// It is safe to have a goroutine calling SendMsg and another goroutine
// calling RecvMsg on the same stream at the same time, but it is not
// safe to call RecvMsg on the same stream in different goroutines.
RecvMsg(m any) error
}
// NewStream creates a new Stream for the client side. This is typically
// called by generated code. ctx is used for the lifetime of the stream.
//
// To ensure resources are not leaked due to the stream returned, one of the following
// actions must be performed:
//
// 1. Call Close on the ClientConn.
// 2. Cancel the context provided.
// 3. Call RecvMsg until a non-nil error is returned. A protobuf-generated
// client-streaming RPC, for instance, might use the helper function
// CloseAndRecv (note that CloseSend does not Recv, therefore is not
// guaranteed to release all resources).
// 4. Receive a non-nil, non-io.EOF error from Header or SendMsg.
//
// If none of the above happen, a goroutine and a context will be leaked, and grpc
// will not call the optionally-configured stats handler with a stats.End message.
func (cc *ClientConn) NewStream(ctx context.Context, desc *StreamDesc, method string, opts ...CallOption) (ClientStream, error) {
// allow interceptor to see all applicable call options, which means those
// configured as defaults from dial option as well as per-call options
opts = combine(cc.dopts.callOptions, opts)
if cc.dopts.streamInt != nil {
return cc.dopts.streamInt(ctx, desc, cc, method, newClientStream, opts...)
}
return newClientStream(ctx, desc, cc, method, opts...)
}
// NewClientStream is a wrapper for ClientConn.NewStream.
func NewClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (ClientStream, error) {
return cc.NewStream(ctx, desc, method, opts...)
}
func newClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (_ ClientStream, err error) {
// Start tracking the RPC for idleness purposes. This is where a stream is
// created for both streaming and unary RPCs, and hence is a good place to
// track active RPC count.
if err := cc.idlenessMgr.OnCallBegin(); err != nil {
return nil, err
}
// Add a calloption, to decrement the active call count, that gets executed
// when the RPC completes.
opts = append([]CallOption{OnFinish(func(error) { cc.idlenessMgr.OnCallEnd() })}, opts...)
if md, added, ok := metadataFromOutgoingContextRaw(ctx); ok {
// validate md
if err := imetadata.Validate(md); err != nil {
return nil, status.Error(codes.Internal, err.Error())
}
// validate added
for _, kvs := range added {
for i := 0; i < len(kvs); i += 2 {
if err := imetadata.ValidatePair(kvs[i], kvs[i+1]); err != nil {
return nil, status.Error(codes.Internal, err.Error())
}
}
}
}
if channelz.IsOn() {
cc.incrCallsStarted()
defer func() {
if err != nil {
cc.incrCallsFailed()
}
}()
}
// Provide an opportunity for the first RPC to see the first service config
// provided by the resolver.
if err := cc.waitForResolvedAddrs(ctx); err != nil {
return nil, err
}
var mc serviceconfig.MethodConfig
var onCommit func()
var newStream = func(ctx context.Context, done func()) (iresolver.ClientStream, error) {
return newClientStreamWithParams(ctx, desc, cc, method, mc, onCommit, done, opts...)
}
rpcInfo := iresolver.RPCInfo{Context: ctx, Method: method}
rpcConfig, err := cc.safeConfigSelector.SelectConfig(rpcInfo)
if err != nil {
if st, ok := status.FromError(err); ok {
// Restrict the code to the list allowed by gRFC A54.
if istatus.IsRestrictedControlPlaneCode(st) {
err = status.Errorf(codes.Internal, "config selector returned illegal status: %v", err)
}
return nil, err
}
return nil, toRPCErr(err)
}
if rpcConfig != nil {
if rpcConfig.Context != nil {
ctx = rpcConfig.Context
}
mc = rpcConfig.MethodConfig
onCommit = rpcConfig.OnCommitted
if rpcConfig.Interceptor != nil {
rpcInfo.Context = nil
ns := newStream
newStream = func(ctx context.Context, done func()) (iresolver.ClientStream, error) {
cs, err := rpcConfig.Interceptor.NewStream(ctx, rpcInfo, done, ns)
if err != nil {
return nil, toRPCErr(err)
}
return cs, nil
}
}
}
return newStream(ctx, func() {})
}
func newClientStreamWithParams(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, mc serviceconfig.MethodConfig, onCommit, doneFunc func(), opts ...CallOption) (_ iresolver.ClientStream, err error) {
c := defaultCallInfo()
if mc.WaitForReady != nil {
c.failFast = !*mc.WaitForReady
}
// Possible context leak:
// The cancel function for the child context we create will only be called
// when RecvMsg returns a non-nil error, if the ClientConn is closed, or if
// an error is generated by SendMsg.
// https://github.com/grpc/grpc-go/issues/1818.
var cancel context.CancelFunc
if mc.Timeout != nil && *mc.Timeout >= 0 {
ctx, cancel = context.WithTimeout(ctx, *mc.Timeout)
} else {
ctx, cancel = context.WithCancel(ctx)
}
defer func() {
if err != nil {
cancel()
}
}()
for _, o := range opts {
if err := o.before(c); err != nil {
return nil, toRPCErr(err)
}
}
c.maxSendMessageSize = getMaxSize(mc.MaxReqSize, c.maxSendMessageSize, defaultClientMaxSendMessageSize)
c.maxReceiveMessageSize = getMaxSize(mc.MaxRespSize, c.maxReceiveMessageSize, defaultClientMaxReceiveMessageSize)
if err := setCallInfoCodec(c); err != nil {
return nil, err
}
callHdr := &transport.CallHdr{
Host: cc.authority,
Method: method,
ContentSubtype: c.contentSubtype,
DoneFunc: doneFunc,
}
// Set our outgoing compression according to the UseCompressor CallOption, if
// set. In that case, also find the compressor from the encoding package.
// Otherwise, use the compressor configured by the WithCompressor DialOption,
// if set.
var cp Compressor
var comp encoding.Compressor
if ct := c.compressorType; ct != "" {
callHdr.SendCompress = ct
if ct != encoding.Identity {
comp = encoding.GetCompressor(ct)
if comp == nil {
return nil, status.Errorf(codes.Internal, "grpc: Compressor is not installed for requested grpc-encoding %q", ct)
}
}
} else if cc.dopts.cp != nil {
callHdr.SendCompress = cc.dopts.cp.Type()
cp = cc.dopts.cp
}
if c.creds != nil {
callHdr.Creds = c.creds
}
cs := &clientStream{
callHdr: callHdr,
ctx: ctx,
methodConfig: &mc,
opts: opts,
callInfo: c,
cc: cc,
desc: desc,
codec: c.codec,
cp: cp,
comp: comp,
cancel: cancel,
firstAttempt: true,
onCommit: onCommit,
}
if !cc.dopts.disableRetry {
cs.retryThrottler = cc.retryThrottler.Load().(*retryThrottler)
}
if ml := binarylog.GetMethodLogger(method); ml != nil {
cs.binlogs = append(cs.binlogs, ml)
}
if cc.dopts.binaryLogger != nil {
if ml := cc.dopts.binaryLogger.GetMethodLogger(method); ml != nil {
cs.binlogs = append(cs.binlogs, ml)
}
}
// Pick the transport to use and create a new stream on the transport.
// Assign cs.attempt upon success.
op := func(a *csAttempt) error {
if err := a.getTransport(); err != nil {
return err
}
if err := a.newStream(); err != nil {
return err
}
// Because this operation is always called either here (while creating
// the clientStream) or by the retry code while locked when replaying
// the operation, it is safe to access cs.attempt directly.
cs.attempt = a
return nil
}
if err := cs.withRetry(op, func() { cs.bufferForRetryLocked(0, op) }); err != nil {
return nil, err
}
if len(cs.binlogs) != 0 {
md, _ := metadata.FromOutgoingContext(ctx)
logEntry := &binarylog.ClientHeader{
OnClientSide: true,
Header: md,
MethodName: method,
Authority: cs.cc.authority,
}
if deadline, ok := ctx.Deadline(); ok {
logEntry.Timeout = time.Until(deadline)
if logEntry.Timeout < 0 {
logEntry.Timeout = 0
}
}
for _, binlog := range cs.binlogs {
binlog.Log(cs.ctx, logEntry)
}
}
if desc != unaryStreamDesc {
// Listen on cc and stream contexts to cleanup when the user closes the
// ClientConn or cancels the stream context. In all other cases, an error
// should already be injected into the recv buffer by the transport, which
// the client will eventually receive, and then we will cancel the stream's
// context in clientStream.finish.
go func() {
select {
case <-cc.ctx.Done():
cs.finish(ErrClientConnClosing)
case <-ctx.Done():
cs.finish(toRPCErr(ctx.Err()))
}
}()
}
return cs, nil
}
// newAttemptLocked creates a new csAttempt without a transport or stream.
func (cs *clientStream) newAttemptLocked(isTransparent bool) (*csAttempt, error) {
if err := cs.ctx.Err(); err != nil {
return nil, toRPCErr(err)
}
if err := cs.cc.ctx.Err(); err != nil {
return nil, ErrClientConnClosing
}
ctx := newContextWithRPCInfo(cs.ctx, cs.callInfo.failFast, cs.callInfo.codec, cs.cp, cs.comp)
method := cs.callHdr.Method
var beginTime time.Time
shs := cs.cc.dopts.copts.StatsHandlers
for _, sh := range shs {
ctx = sh.TagRPC(ctx, &stats.RPCTagInfo{FullMethodName: method, FailFast: cs.callInfo.failFast})
beginTime = time.Now()
begin := &stats.Begin{
Client: true,
BeginTime: beginTime,
FailFast: cs.callInfo.failFast,
IsClientStream: cs.desc.ClientStreams,
IsServerStream: cs.desc.ServerStreams,
IsTransparentRetryAttempt: isTransparent,
}
sh.HandleRPC(ctx, begin)
}
var trInfo *traceInfo
if EnableTracing {
trInfo = &traceInfo{
tr: newTrace("grpc.Sent."+methodFamily(method), method),
firstLine: firstLine{
client: true,
},
}
if deadline, ok := ctx.Deadline(); ok {
trInfo.firstLine.deadline = time.Until(deadline)
}
trInfo.tr.LazyLog(&trInfo.firstLine, false)
ctx = newTraceContext(ctx, trInfo.tr)
}
if cs.cc.parsedTarget.URL.Scheme == internal.GRPCResolverSchemeExtraMetadata {
// Add extra metadata (metadata that will be added by transport) to context
// so the balancer can see them.
ctx = grpcutil.WithExtraMetadata(ctx, metadata.Pairs(
"content-type", grpcutil.ContentType(cs.callHdr.ContentSubtype),
))
}
return &csAttempt{
ctx: ctx,
beginTime: beginTime,
cs: cs,
dc: cs.cc.dopts.dc,
statsHandlers: shs,
trInfo: trInfo,
}, nil
}
func (a *csAttempt) getTransport() error {
cs := a.cs
var err error
a.t, a.pickResult, err = cs.cc.getTransport(a.ctx, cs.callInfo.failFast, cs.callHdr.Method)
if err != nil {
if de, ok := err.(dropError); ok {
err = de.error
a.drop = true
}
return err
}
if a.trInfo != nil {
a.trInfo.firstLine.SetRemoteAddr(a.t.RemoteAddr())
}
return nil
}
func (a *csAttempt) newStream() error {
cs := a.cs
cs.callHdr.PreviousAttempts = cs.numRetries
// Merge metadata stored in PickResult, if any, with existing call metadata.
// It is safe to overwrite the csAttempt's context here, since all state
// maintained in it are local to the attempt. When the attempt has to be
// retried, a new instance of csAttempt will be created.
if a.pickResult.Metadata != nil {
// We currently do not have a function it the metadata package which
// merges given metadata with existing metadata in a context. Existing
// function `AppendToOutgoingContext()` takes a variadic argument of key
// value pairs.
//
// TODO: Make it possible to retrieve key value pairs from metadata.MD
// in a form passable to AppendToOutgoingContext(), or create a version
// of AppendToOutgoingContext() that accepts a metadata.MD.
md, _ := metadata.FromOutgoingContext(a.ctx)
md = metadata.Join(md, a.pickResult.Metadata)
a.ctx = metadata.NewOutgoingContext(a.ctx, md)
}
s, err := a.t.NewStream(a.ctx, cs.callHdr)
if err != nil {
nse, ok := err.(*transport.NewStreamError)
if !ok {
// Unexpected.
return err
}
if nse.AllowTransparentRetry {
a.allowTransparentRetry = true
}
// Unwrap and convert error.
return toRPCErr(nse.Err)
}
a.s = s
a.p = &parser{r: s, recvBufferPool: a.cs.cc.dopts.recvBufferPool}
return nil
}
// clientStream implements a client side Stream.
type clientStream struct {
callHdr *transport.CallHdr
opts []CallOption
callInfo *callInfo
cc *ClientConn
desc *StreamDesc
codec baseCodec
cp Compressor
comp encoding.Compressor
cancel context.CancelFunc // cancels all attempts
sentLast bool // sent an end stream
methodConfig *MethodConfig
ctx context.Context // the application's context, wrapped by stats/tracing
retryThrottler *retryThrottler // The throttler active when the RPC began.
binlogs []binarylog.MethodLogger
// serverHeaderBinlogged is a boolean for whether server header has been
// logged. Server header will be logged when the first time one of those
// happens: stream.Header(), stream.Recv().
//
// It's only read and used by Recv() and Header(), so it doesn't need to be
// synchronized.
serverHeaderBinlogged bool
mu sync.Mutex
firstAttempt bool // if true, transparent retry is valid
numRetries int // exclusive of transparent retry attempt(s)
numRetriesSincePushback int // retries since pushback; to reset backoff
finished bool // TODO: replace with atomic cmpxchg or sync.Once?
// attempt is the active client stream attempt.
// The only place where it is written is the newAttemptLocked method and this method never writes nil.
// So, attempt can be nil only inside newClientStream function when clientStream is first created.
// One of the first things done after clientStream's creation, is to call newAttemptLocked which either
// assigns a non nil value to the attempt or returns an error. If an error is returned from newAttemptLocked,
// then newClientStream calls finish on the clientStream and returns. So, finish method is the only
// place where we need to check if the attempt is nil.
attempt *csAttempt
// TODO(hedging): hedging will have multiple attempts simultaneously.
committed bool // active attempt committed for retry?
onCommit func()
buffer []func(a *csAttempt) error // operations to replay on retry
bufferSize int // current size of buffer
}
// csAttempt implements a single transport stream attempt within a
// clientStream.
type csAttempt struct {
ctx context.Context
cs *clientStream
t transport.ClientTransport
s *transport.Stream
p *parser
pickResult balancer.PickResult
finished bool
dc Decompressor
decomp encoding.Compressor
decompSet bool
mu sync.Mutex // guards trInfo.tr
// trInfo may be nil (if EnableTracing is false).
// trInfo.tr is set when created (if EnableTracing is true),
// and cleared when the finish method is called.
trInfo *traceInfo
statsHandlers []stats.Handler
beginTime time.Time
// set for newStream errors that may be transparently retried
allowTransparentRetry bool
// set for pick errors that are returned as a status
drop bool
}
func (cs *clientStream) commitAttemptLocked() {
if !cs.committed && cs.onCommit != nil {
cs.onCommit()
}
cs.committed = true
cs.buffer = nil
}
func (cs *clientStream) commitAttempt() {
cs.mu.Lock()
cs.commitAttemptLocked()
cs.mu.Unlock()
}
// shouldRetry returns nil if the RPC should be retried; otherwise it returns
// the error that should be returned by the operation. If the RPC should be
// retried, the bool indicates whether it is being retried transparently.
func (a *csAttempt) shouldRetry(err error) (bool, error) {
cs := a.cs
if cs.finished || cs.committed || a.drop {
// RPC is finished or committed or was dropped by the picker; cannot retry.
return false, err
}
if a.s == nil && a.allowTransparentRetry {
return true, nil
}
// Wait for the trailers.
unprocessed := false
if a.s != nil {
<-a.s.Done()
unprocessed = a.s.Unprocessed()
}
if cs.firstAttempt && unprocessed {
// First attempt, stream unprocessed: transparently retry.
return true, nil
}
if cs.cc.dopts.disableRetry {
return false, err
}
pushback := 0
hasPushback := false
if a.s != nil {
if !a.s.TrailersOnly() {
return false, err
}
// TODO(retry): Move down if the spec changes to not check server pushback
// before considering this a failure for throttling.
sps := a.s.Trailer()["grpc-retry-pushback-ms"]
if len(sps) == 1 {
var e error
if pushback, e = strconv.Atoi(sps[0]); e != nil || pushback < 0 {
channelz.Infof(logger, cs.cc.channelzID, "Server retry pushback specified to abort (%q).", sps[0])
cs.retryThrottler.throttle() // This counts as a failure for throttling.
return false, err
}
hasPushback = true
} else if len(sps) > 1 {
channelz.Warningf(logger, cs.cc.channelzID, "Server retry pushback specified multiple values (%q); not retrying.", sps)
cs.retryThrottler.throttle() // This counts as a failure for throttling.
return false, err
}
}
var code codes.Code
if a.s != nil {
code = a.s.Status().Code()
} else {
code = status.Code(err)
}
rp := cs.methodConfig.RetryPolicy
if rp == nil || !rp.RetryableStatusCodes[code] {
return false, err
}
// Note: the ordering here is important; we count this as a failure
// only if the code matched a retryable code.
if cs.retryThrottler.throttle() {
return false, err
}
if cs.numRetries+1 >= rp.MaxAttempts {
return false, err
}
var dur time.Duration
if hasPushback {
dur = time.Millisecond * time.Duration(pushback)
cs.numRetriesSincePushback = 0
} else {
fact := math.Pow(rp.BackoffMultiplier, float64(cs.numRetriesSincePushback))
cur := float64(rp.InitialBackoff) * fact
if max := float64(rp.MaxBackoff); cur > max {
cur = max
}
dur = time.Duration(grpcrand.Int63n(int64(cur)))
cs.numRetriesSincePushback++
}
// TODO(dfawley): we could eagerly fail here if dur puts us past the
// deadline, but unsure if it is worth doing.
t := time.NewTimer(dur)
select {
case <-t.C:
cs.numRetries++
return false, nil
case <-cs.ctx.Done():
t.Stop()
return false, status.FromContextError(cs.ctx.Err()).Err()
}
}
// Returns nil if a retry was performed and succeeded; error otherwise.
func (cs *clientStream) retryLocked(attempt *csAttempt, lastErr error) error {
for {
attempt.finish(toRPCErr(lastErr))
isTransparent, err := attempt.shouldRetry(lastErr)
if err != nil {
cs.commitAttemptLocked()
return err
}
cs.firstAttempt = false
attempt, err = cs.newAttemptLocked(isTransparent)
if err != nil {
// Only returns error if the clientconn is closed or the context of
// the stream is canceled.
return err
}
// Note that the first op in the replay buffer always sets cs.attempt
// if it is able to pick a transport and create a stream.
if lastErr = cs.replayBufferLocked(attempt); lastErr == nil {
return nil
}
}
}
func (cs *clientStream) Context() context.Context {
cs.commitAttempt()
// No need to lock before using attempt, since we know it is committed and
// cannot change.
if cs.attempt.s != nil {
return cs.attempt.s.Context()
}
return cs.ctx
}
func (cs *clientStream) withRetry(op func(a *csAttempt) error, onSuccess func()) error {
cs.mu.Lock()
for {
if cs.committed {
cs.mu.Unlock()
// toRPCErr is used in case the error from the attempt comes from
// NewClientStream, which intentionally doesn't return a status
// error to allow for further inspection; all other errors should
// already be status errors.
return toRPCErr(op(cs.attempt))
}
if len(cs.buffer) == 0 {
// For the first op, which controls creation of the stream and
// assigns cs.attempt, we need to create a new attempt inline
// before executing the first op. On subsequent ops, the attempt
// is created immediately before replaying the ops.
var err error
if cs.attempt, err = cs.newAttemptLocked(false /* isTransparent */); err != nil {
cs.mu.Unlock()
cs.finish(err)
return err
}
}
a := cs.attempt
cs.mu.Unlock()
err := op(a)
cs.mu.Lock()
if a != cs.attempt {
// We started another attempt already.
continue
}
if err == io.EOF {
<-a.s.Done()
}
if err == nil || (err == io.EOF && a.s.Status().Code() == codes.OK) {
onSuccess()
cs.mu.Unlock()
return err
}
if err := cs.retryLocked(a, err); err != nil {
cs.mu.Unlock()
return err
}
}
}
func (cs *clientStream) Header() (metadata.MD, error) {
var m metadata.MD
err := cs.withRetry(func(a *csAttempt) error {
var err error
m, err = a.s.Header()
return toRPCErr(err)
}, cs.commitAttemptLocked)
if m == nil && err == nil {
// The stream ended with success. Finish the clientStream.
err = io.EOF
}
if err != nil {
cs.finish(err)
// Do not return the error. The user should get it by calling Recv().
return nil, nil
}
if len(cs.binlogs) != 0 && !cs.serverHeaderBinlogged && m != nil {
// Only log if binary log is on and header has not been logged, and
// there is actually headers to log.
logEntry := &binarylog.ServerHeader{
OnClientSide: true,
Header: m,
PeerAddr: nil,
}
if peer, ok := peer.FromContext(cs.Context()); ok {
logEntry.PeerAddr = peer.Addr
}
cs.serverHeaderBinlogged = true
for _, binlog := range cs.binlogs {
binlog.Log(cs.ctx, logEntry)
}
}
return m, nil
}
func (cs *clientStream) Trailer() metadata.MD {
// On RPC failure, we never need to retry, because usage requires that
// RecvMsg() returned a non-nil error before calling this function is valid.
// We would have retried earlier if necessary.
//
// Commit the attempt anyway, just in case users are not following those
// directions -- it will prevent races and should not meaningfully impact
// performance.
cs.commitAttempt()
if cs.attempt.s == nil {
return nil
}
return cs.attempt.s.Trailer()
}
func (cs *clientStream) replayBufferLocked(attempt *csAttempt) error {
for _, f := range cs.buffer {
if err := f(attempt); err != nil {
return err
}
}
return nil
}
func (cs *clientStream) bufferForRetryLocked(sz int, op func(a *csAttempt) error) {
// Note: we still will buffer if retry is disabled (for transparent retries).
if cs.committed {
return
}
cs.bufferSize += sz
if cs.bufferSize > cs.callInfo.maxRetryRPCBufferSize {
cs.commitAttemptLocked()
return
}
cs.buffer = append(cs.buffer, op)
}
func (cs *clientStream) SendMsg(m any) (err error) {
defer func() {
if err != nil && err != io.EOF {
// Call finish on the client stream for errors generated by this SendMsg
// call, as these indicate problems created by this client. (Transport
// errors are converted to an io.EOF error in csAttempt.sendMsg; the real
// error will be returned from RecvMsg eventually in that case, or be
// retried.)
cs.finish(err)
}
}()
if cs.sentLast {
return status.Errorf(codes.Internal, "SendMsg called after CloseSend")
}
if !cs.desc.ClientStreams {
cs.sentLast = true
}
// load hdr, payload, data
hdr, payload, data, err := prepareMsg(m, cs.codec, cs.cp, cs.comp)
if err != nil {
return err
}
// TODO(dfawley): should we be checking len(data) instead?
if len(payload) > *cs.callInfo.maxSendMessageSize {
return status.Errorf(codes.ResourceExhausted, "trying to send message larger than max (%d vs. %d)", len(payload), *cs.callInfo.maxSendMessageSize)
}
op := func(a *csAttempt) error {
return a.sendMsg(m, hdr, payload, data)
}
err = cs.withRetry(op, func() { cs.bufferForRetryLocked(len(hdr)+len(payload), op) })
if len(cs.binlogs) != 0 && err == nil {
cm := &binarylog.ClientMessage{
OnClientSide: true,
Message: data,
}
for _, binlog := range cs.binlogs {
binlog.Log(cs.ctx, cm)
}
}
return err
}
func (cs *clientStream) RecvMsg(m any) error {
if len(cs.binlogs) != 0 && !cs.serverHeaderBinlogged {
// Call Header() to binary log header if it's not already logged.
cs.Header()
}
var recvInfo *payloadInfo
if len(cs.binlogs) != 0 {
recvInfo = &payloadInfo{}
}
err := cs.withRetry(func(a *csAttempt) error {
return a.recvMsg(m, recvInfo)
}, cs.commitAttemptLocked)
if len(cs.binlogs) != 0 && err == nil {
sm := &binarylog.ServerMessage{
OnClientSide: true,
Message: recvInfo.uncompressedBytes,
}
for _, binlog := range cs.binlogs {
binlog.Log(cs.ctx, sm)
}
}
if err != nil || !cs.desc.ServerStreams {
// err != nil or non-server-streaming indicates end of stream.
cs.finish(err)
}
return err
}
func (cs *clientStream) CloseSend() error {
if cs.sentLast {
// TODO: return an error and finish the stream instead, due to API misuse?
return nil
}
cs.sentLast = true
op := func(a *csAttempt) error {
a.t.Write(a.s, nil, nil, &transport.Options{Last: true})
// Always return nil; io.EOF is the only error that might make sense
// instead, but there is no need to signal the client to call RecvMsg
// as the only use left for the stream after CloseSend is to call
// RecvMsg. This also matches historical behavior.
return nil
}
cs.withRetry(op, func() { cs.bufferForRetryLocked(0, op) })
if len(cs.binlogs) != 0 {
chc := &binarylog.ClientHalfClose{
OnClientSide: true,
}
for _, binlog := range cs.binlogs {
binlog.Log(cs.ctx, chc)
}
}
// We never returned an error here for reasons.
return nil
}
func (cs *clientStream) finish(err error) {
if err == io.EOF {
// Ending a stream with EOF indicates a success.
err = nil
}
cs.mu.Lock()
if cs.finished {
cs.mu.Unlock()
return
}
cs.finished = true
for _, onFinish := range cs.callInfo.onFinish {
onFinish(err)
}
cs.commitAttemptLocked()
if cs.attempt != nil {
cs.attempt.finish(err)
// after functions all rely upon having a stream.
if cs.attempt.s != nil {
for _, o := range cs.opts {
o.after(cs.callInfo, cs.attempt)
}
}
}
cs.mu.Unlock()
// Only one of cancel or trailer needs to be logged.
if len(cs.binlogs) != 0 {