grpcproxy: client watch adapter

proxy/grpcproxy/watch_client_adapter.go

@@ -0,0 +1,141 @@
+// Copyright 2016 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 grpcproxy
+
+import (
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+type ws2wc struct{ wserv pb.WatchServer }
+
+func WatchServerToWatchClient(wserv pb.WatchServer) pb.WatchClient {
+	return &ws2wc{wserv}
+}
+
+func (s *ws2wc) Watch(ctx context.Context, opts ...grpc.CallOption) (pb.Watch_WatchClient, error) {
+	ch1, ch2 := make(chan interface{}), make(chan interface{})
+	headerc, trailerc := make(chan metadata.MD, 1), make(chan metadata.MD, 1)
+	wclient := &ws2wcClientStream{chanClientStream{headerc, trailerc, &chanStream{ch1, ch2, ctx}}}
+	wserver := &ws2wcServerStream{chanServerStream{headerc, trailerc, &chanStream{ch2, ch1, ctx}}}
+	go s.wserv.Watch(wserver)
+	return wclient, nil
+}
+
+// ws2wcClientStream implements Watch_WatchClient
+type ws2wcClientStream struct{ chanClientStream }
+
+// ws2wcServerStream implements Watch_WatchServer
+type ws2wcServerStream struct{ chanServerStream }
+
+func (s *ws2wcClientStream) Send(wr *pb.WatchRequest) error {
+	return s.SendMsg(wr)
+}
+func (s *ws2wcClientStream) Recv() (*pb.WatchResponse, error) {
+	var v interface{}
+	if err := s.RecvMsg(&v); err != nil {
+		return nil, err
+	}
+	return v.(*pb.WatchResponse), nil
+}
+
+func (s *ws2wcServerStream) Send(wr *pb.WatchResponse) error {
+	return s.SendMsg(wr)
+}
+func (s *ws2wcServerStream) Recv() (*pb.WatchRequest, error) {
+	var v interface{}
+	if err := s.RecvMsg(&v); err != nil {
+		return nil, err
+	}
+	return v.(*pb.WatchRequest), nil
+}
+
+// chanServerStream implements grpc.ServerStream with a chanStream
+type chanServerStream struct {
+	headerc  chan<- metadata.MD
+	trailerc chan<- metadata.MD
+	grpc.Stream
+}
+
+func (ss *chanServerStream) SendHeader(md metadata.MD) error {
+	select {
+	case ss.headerc <- md:
+		return nil
+	case <-ss.Context().Done():
+	}
+	return ss.Context().Err()
+}
+
+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
+	grpc.Stream
+}
+
+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 (s *chanClientStream) CloseSend() error { return nil }
+
+// chanStream implements grpc.Stream using channels
+type chanStream struct {
+	recvc <-chan interface{}
+	sendc chan<- interface{}
+	ctx   context.Context
+}
+
+func (s *chanStream) Context() context.Context { return s.Context() }
+
+func (s *chanStream) SendMsg(m interface{}) error {
+	select {
+	case s.sendc <- m:
+		return nil
+	case <-s.ctx.Done():
+	}
+	return s.ctx.Err()
+}
+
+func (s *chanStream) RecvMsg(m interface{}) error {
+	v := m.(*interface{})
+	select {
+	case m = <-s.recvc:
+		*v = m
+		return nil
+	case <-s.ctx.Done():
+	}
+	return s.ctx.Err()
+}