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// Copyright 2017 The etcd 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 adapter
import (
"context"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/status"
)
// chanServerStream implements grpc.ServerStream with a chanStream
type chanServerStream struct {
headerc chan<- metadata.MD
trailerc chan<- metadata.MD
grpc.Stream
headers []metadata.MD
}
func (ss *chanServerStream) SendHeader(md metadata.MD) error {
if ss.headerc == nil {
return errAlreadySentHeader
}
outmd := make(map[string][]string)
for _, h := range append(ss.headers, md) {
for k, v := range h {
outmd[k] = v
}
}
select {
case ss.headerc <- outmd:
ss.headerc = nil
ss.headers = nil
return nil
case <-ss.Context().Done():
}
return ss.Context().Err()
}
func (ss *chanServerStream) SetHeader(md metadata.MD) error {
if ss.headerc == nil {
return errAlreadySentHeader
}
ss.headers = append(ss.headers, md)
return nil
}
func (ss *chanServerStream) SetTrailer(md metadata.MD) {
ss.trailerc <- md
}
// chanClientStream implements grpc.ClientStream with a chanStream
type chanClientStream struct {
headerc <-chan metadata.MD
trailerc <-chan metadata.MD
*chanStream
}
func (cs *chanClientStream) Header() (metadata.MD, error) {
select {
case md := <-cs.headerc:
return md, nil
case <-cs.Context().Done():
}
return nil, cs.Context().Err()
}
func (cs *chanClientStream) Trailer() metadata.MD {
select {
case md := <-cs.trailerc:
return md
case <-cs.Context().Done():
return nil
}
}
func (cs *chanClientStream) CloseSend() error {
close(cs.chanStream.sendc)
return nil
}
// chanStream implements grpc.Stream using channels
type chanStream struct {
recvc <-chan interface{}
sendc chan<- interface{}
ctx context.Context
cancel context.CancelFunc
}
func (s *chanStream) Context() context.Context { return s.ctx }
func (s *chanStream) SendMsg(m interface{}) error {
select {
case s.sendc <- m:
if err, ok := m.(error); ok {
return err
}
return nil
case <-s.ctx.Done():
}
return s.ctx.Err()
}
func (s *chanStream) RecvMsg(m interface{}) error {
v := m.(*interface{})
for {
select {
case msg, ok := <-s.recvc:
if !ok {
return status.Error(codes.Canceled, "the client connection is closing")
}
if err, ok := msg.(error); ok {
return err
}
*v = msg
return nil
case <-s.ctx.Done():
}
if len(s.recvc) == 0 {
// prioritize any pending recv messages over canceled context
break
}
}
return s.ctx.Err()
}
func newPipeStream(ctx context.Context, ssHandler func(chanServerStream) error) chanClientStream {
// ch1 is buffered so server can send error on close
ch1, ch2 := make(chan interface{}, 1), make(chan interface{})
headerc, trailerc := make(chan metadata.MD, 1), make(chan metadata.MD, 1)
cctx, ccancel := context.WithCancel(ctx)
cli := &chanStream{recvc: ch1, sendc: ch2, ctx: cctx, cancel: ccancel}
cs := chanClientStream{headerc, trailerc, cli}
sctx, scancel := context.WithCancel(ctx)
srv := &chanStream{recvc: ch2, sendc: ch1, ctx: sctx, cancel: scancel}
ss := chanServerStream{headerc, trailerc, srv, nil}
go func() {
if err := ssHandler(ss); err != nil {
select {
case srv.sendc <- err:
case <-sctx.Done():
case <-cctx.Done():
}
}
scancel()
ccancel()
}()
return cs
}
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