| // Copyright 2018 Google LLC |
| // |
| // 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 ( |
| "context" |
| "io" |
| "sync" |
| "time" |
| |
| gax "github.com/googleapis/gax-go/v2" |
| 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) |
| cancel context.CancelFunc |
| |
| mu sync.Mutex |
| spc *pb.Subscriber_StreamingPullClient |
| err error // permanent error |
| } |
| |
| // for testing |
| type streamingPullFunc func(context.Context, ...gax.CallOption) (pb.Subscriber_StreamingPullClient, error) |
| |
| func newPullStream(ctx context.Context, streamingPull streamingPullFunc, subName string, maxOutstandingMessages, maxOutstandingBytes int, maxDurationPerLeaseExtension time.Duration) *pullStream { |
| ctx = withSubscriptionKey(ctx, subName) |
| ctx, cancel := context.WithCancel(ctx) |
| return &pullStream{ |
| ctx: ctx, |
| cancel: cancel, |
| open: func() (pb.Subscriber_StreamingPullClient, error) { |
| spc, err := streamingPull(ctx, gax.WithGRPCOptions(grpc.MaxCallRecvMsgSize(maxSendRecvBytes))) |
| if err == nil { |
| recordStat(ctx, StreamRequestCount, 1) |
| streamAckDeadline := int32(maxDurationPerLeaseExtension / time.Second) |
| // By default, maxDurationPerLeaseExtension, aka MaxExtensionPeriod, is disabled, |
| // so in these cases, use a healthy default of 60 seconds. |
| if streamAckDeadline <= 0 { |
| streamAckDeadline = 60 |
| } |
| err = spc.Send(&pb.StreamingPullRequest{ |
| Subscription: subName, |
| StreamAckDeadlineSeconds: streamAckDeadline, |
| MaxOutstandingMessages: int64(maxOutstandingMessages), |
| MaxOutstandingBytes: int64(maxOutstandingBytes), |
| }) |
| } |
| 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. |
| 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.openWithRetry() // Any error from openWithRetry is permanent. |
| return s.spc, s.err |
| } |
| |
| func (s *pullStream) openWithRetry() (pb.Subscriber_StreamingPullClient, error) { |
| r := defaultRetryer{} |
| for { |
| recordStat(s.ctx, StreamOpenCount, 1) |
| spc, err := s.open() |
| bo, shouldRetry := r.Retry(err) |
| if err != nil && shouldRetry { |
| recordStat(s.ctx, StreamRetryCount, 1) |
| if err := gax.Sleep(s.ctx, bo); err != nil { |
| return nil, err |
| } |
| continue |
| } |
| return spc, err |
| } |
| } |
| |
| func (s *pullStream) call(f func(pb.Subscriber_StreamingPullClient) error, opts ...gax.CallOption) error { |
| var settings gax.CallSettings |
| for _, opt := range opts { |
| opt.Resolve(&settings) |
| } |
| var r gax.Retryer = &defaultRetryer{} |
| if settings.Retry != nil { |
| r = settings.Retry() |
| } |
| |
| var ( |
| spc *pb.Subscriber_StreamingPullClient |
| err error |
| ) |
| for { |
| spc, err = s.get(spc) |
| if err != nil { |
| return err |
| } |
| start := time.Now() |
| err = f(*spc) |
| if err != nil { |
| bo, shouldRetry := r.Retry(err) |
| if shouldRetry { |
| recordStat(s.ctx, StreamRetryCount, 1) |
| if time.Since(start) < 30*time.Second { // don't sleep if we've been blocked for a while |
| if err := gax.Sleep(s.ctx, bo); err != nil { |
| return err |
| } |
| } |
| continue |
| } |
| s.mu.Lock() |
| s.err = err |
| s.mu.Unlock() |
| } |
| return err |
| } |
| } |
| |
| func (s *pullStream) Send(req *pb.StreamingPullRequest) error { |
| return s.call(func(spc pb.Subscriber_StreamingPullClient) error { |
| recordStat(s.ctx, AckCount, int64(len(req.AckIds))) |
| zeroes := 0 |
| for _, mds := range req.ModifyDeadlineSeconds { |
| if mds == 0 { |
| zeroes++ |
| } |
| } |
| recordStat(s.ctx, NackCount, int64(zeroes)) |
| recordStat(s.ctx, ModAckCount, int64(len(req.ModifyDeadlineSeconds)-zeroes)) |
| recordStat(s.ctx, StreamRequestCount, 1) |
| 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 |
| recordStat(s.ctx, StreamResponseCount, 1) |
| res, err = spc.Recv() |
| return err |
| }, gax.WithRetry(func() gax.Retryer { return &streamingPullRetryer{defaultRetryer: &defaultRetryer{}} })) |
| 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 |
| } |