| // Copyright 2018 Google Inc. All Rights Reserved. |
| // |
| // 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 pubsub |
| |
| import ( |
| "io" |
| "sync" |
| |
| vkit "cloud.google.com/go/pubsub/apiv1" |
| gax "github.com/googleapis/gax-go" |
| "golang.org/x/net/context" |
| pb "google.golang.org/genproto/googleapis/pubsub/v1" |
| "google.golang.org/grpc" |
| ) |
| |
| // A pullStream supports the methods of a StreamingPullClient, but re-opens |
| // the stream on a retryable error. |
| type pullStream struct { |
| ctx context.Context |
| open func() (pb.Subscriber_StreamingPullClient, error) |
| |
| mu sync.Mutex |
| spc *pb.Subscriber_StreamingPullClient |
| err error // permanent error |
| } |
| |
| func newPullStream(ctx context.Context, subc *vkit.SubscriberClient, subName string, ackDeadlineSecs int32) *pullStream { |
| return &pullStream{ |
| ctx: ctx, |
| open: func() (pb.Subscriber_StreamingPullClient, error) { |
| spc, err := subc.StreamingPull(ctx, gax.WithGRPCOptions(grpc.MaxCallRecvMsgSize(maxSendRecvBytes))) |
| if err == nil { |
| err = spc.Send(&pb.StreamingPullRequest{ |
| Subscription: subName, |
| StreamAckDeadlineSeconds: ackDeadlineSecs, |
| }) |
| } |
| if err != nil { |
| return nil, err |
| } |
| return spc, nil |
| }, |
| } |
| } |
| |
| // get returns either a valid *StreamingPullClient (SPC), or a permanent error. |
| // If the argument is nil, this is the first call for an RPC, and the current |
| // SPC will be returned (or a new one will be opened). Otherwise, this call is a |
| // request to re-open the stream because of a retryable error, and the argument |
| // is a pointer to the SPC that returned the error. |
| func (s *pullStream) get(spc *pb.Subscriber_StreamingPullClient) (*pb.Subscriber_StreamingPullClient, error) { |
| s.mu.Lock() |
| defer s.mu.Unlock() |
| // A stored error is permanent. |
| if s.err != nil { |
| return nil, s.err |
| } |
| // If the context is done, so are we. |
| select { |
| case <-s.ctx.Done(): |
| s.err = s.ctx.Err() |
| return nil, s.err |
| default: |
| } |
| // TODO(jba): We can use the following instead of the above after we drop support for 1.8: |
| // s.err = s.ctx.Err() |
| // if s.err != nil { |
| // return nil, s.err |
| // } |
| |
| // If the current and argument SPCs differ, return the current one. This subsumes two cases: |
| // 1. We have an SPC and the caller is getting the stream for the first time. |
| // 2. The caller wants to retry, but they have an older SPC; we've already retried. |
| if spc != s.spc { |
| return s.spc, nil |
| } |
| // Either this is the very first call on this stream (s.spc == nil), or we have a valid |
| // retry request. Either way, open a new stream. |
| // The lock is held here for a long time, but it doesn't matter because no callers could get |
| // anything done anyway. |
| s.spc = new(pb.Subscriber_StreamingPullClient) |
| *s.spc, s.err = s.open() // Setting s.err means any error from open is permanent. Reconsider. |
| return s.spc, s.err |
| } |
| |
| func (s *pullStream) call(f func(pb.Subscriber_StreamingPullClient) error) error { |
| var ( |
| spc *pb.Subscriber_StreamingPullClient |
| err error |
| bo gax.Backoff |
| ) |
| for { |
| spc, err = s.get(spc) |
| if err != nil { |
| // Preserve the existing behavior of not retrying on open. Is that a bug? |
| // (If we do decide to retry, don't retry after we're closed.) |
| return err |
| } |
| err = f(*spc) |
| if err != nil { |
| if isRetryable(err) { |
| gax.Sleep(s.ctx, bo.Pause()) |
| continue |
| } |
| s.err = err |
| } |
| return err |
| } |
| } |
| |
| func (s *pullStream) Send(req *pb.StreamingPullRequest) error { |
| return s.call(func(spc pb.Subscriber_StreamingPullClient) error { |
| return spc.Send(req) |
| }) |
| } |
| |
| func (s *pullStream) Recv() (*pb.StreamingPullResponse, error) { |
| var res *pb.StreamingPullResponse |
| err := s.call(func(spc pb.Subscriber_StreamingPullClient) error { |
| var err error |
| res, err = spc.Recv() |
| return err |
| }) |
| return res, err |
| } |
| |
| func (s *pullStream) CloseSend() error { |
| err := s.call(func(spc pb.Subscriber_StreamingPullClient) error { |
| return spc.CloseSend() |
| }) |
| s.mu.Lock() |
| s.err = io.EOF // should not be retried |
| s.mu.Unlock() |
| return err |
| } |