lostluck commented on code in PR #17955: URL: https://github.com/apache/beam/pull/17955#discussion_r894068750
########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { Review Comment: Don't export the types if a user is never supposed to view it. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { Review Comment: It's good to move this to a function and to have documentation, but unless you expect packages outside of this one to call it, don't export it. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } + + for { + ok := rt.TryClaim(r.Subscription) + if !ok { + return sdf.ResumeProcessingIn(5 * time.Second), nil + } + sub := r.Client.Subscription(r.Subscription) + ctx, cFn := context.WithCancel(context.Background()) + + // Because emitters are not thread safe and synchronous Receive() behavior + // is deprecated, we have to collect messages in a goroutine and pipe them + // out through a channel. + messChan := make(chan *pubsub.Message, 1) + go func(sendch chan<- *pubsub.Message) { + err := sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) { + messChan <- m + }) + if (err != nil) && (err != context.Canceled) { + log.Errorf(ctx, "error reading from PubSub: %v, stopping processing", err) + cFn() + close(messChan) + } + }(messChan) + + // Give the goroutines time to start polling. + time.Sleep(5 * time.Second) Review Comment: Prefer creating a timer instead of sleeing: https://pkg.go.dev/time#NewTimer Then you can "react" to the timer firing with the t.C channel. And then you can avoid the default statement, and sleeping while we wait. Technically, you could also avoid the buffered channel too, which will let everything block. A boolean can be added WRT to see if there were any messages since the last sleep, which can be tripped in the messChan case. The timer case can then check if there was a message, and if so, simply go back to sleep, and if not, reset the bundle. Or something with the timer's Reset method. The only awkward bit is we'd probably want to self checkpoint a little sooner than the Ack deadline on any of the messages, so the runner has time to trigger bundleFinalizing for the messages. But since the client automatically [extends the AckDeadline to up to 60 minutes by default](https://pkg.go.dev/cloud.google.com/go/pubsub#hdr-Deadlines) from it's start of 10 seconds, we're probably fine. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription Review Comment: Definitely a "maybe try this later" improvement, but to allow for more parallelism, if the backlog on a subscription becomes large for example, it could be worth having a "primary" and "secondary" restrictions, where a primary can split into secondary restrictions if the backlog is getting too large, and "secondary" restrictions can terminate when it gets too small. This would require information to be passed between the watermark estimation and the tracker to manage the restrictions, but that's not impossible. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } + + for { + ok := rt.TryClaim(r.Subscription) + if !ok { + return sdf.ResumeProcessingIn(5 * time.Second), nil + } + sub := r.Client.Subscription(r.Subscription) + ctx, cFn := context.WithCancel(context.Background()) + + // Because emitters are not thread safe and synchronous Receive() behavior + // is deprecated, we have to collect messages in a goroutine and pipe them + // out through a channel. + messChan := make(chan *pubsub.Message, 1) + go func(sendch chan<- *pubsub.Message) { + err := sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) { + messChan <- m + }) + if (err != nil) && (err != context.Canceled) { + log.Errorf(ctx, "error reading from PubSub: %v, stopping processing", err) + cFn() + close(messChan) + } + }(messChan) + + // Give the goroutines time to start polling. + time.Sleep(5 * time.Second) + + for { + select { + case m, ok := <-messChan: + if !ok { + log.Debug(context.Background(), "stopping bundle processing") + return sdf.StopProcessing(), nil + } + r.ProcessedMessages = append(r.ProcessedMessages, m) + emit(beam.EventTime(m.PublishTime.UnixMilli()), m.Data) + default: + log.Debug(context.Background(), "cancelling receive context, scheduling resumption") + cFn() + return sdf.ResumeProcessingIn(10 * time.Second), nil + } + } + } +} + +// NativeRead reads messages from a PubSub topic in a streaming context, outputting +// received messages as a PCollection of byte slices. If the provided subscription +// name exists for the given topic, the DoFn will read from that subscription; otherwise, +// a new subscription with the given subscription name will be created and read from. +// +// This feature is experimental and subject to change, including its behavior and function signature. +// Please use the cross-language implementation Read() instead. +func NativeRead(s beam.Scope, project, topic, subscription string) beam.PCollection { + s = s.Scope("pubsubio.NativeRead") + + psRead, err := NewPubSubRead(context.Background(), project, topic, subscription) + if err != nil { + panic(err) + } + return beam.ParDo(s, psRead, beam.Impulse(s)) +} + +// PubSubWrite is a structural DoFn representing writes to a given PubSub topic. +type PubSubWrite struct { + ProjectID string + Topic string + Client *pubsub.Client +} + +// ProcessElement takes a []byte element and publishes it to the provided PubSub +// topic. +func (w *PubSubWrite) ProcessElement(elm []byte) error { + // Initialize PubSub client if one has not been created already + if w.Client == nil { + client, err := pubsub.NewClient(context.Background(), w.ProjectID) + if err != nil { + return err + } + w.Client = client + } Review Comment: Same thing, put it in a Setup method. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } Review Comment: This should happen in a Setup(context.Context) error method (which can return error). ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } + + for { + ok := rt.TryClaim(r.Subscription) + if !ok { + return sdf.ResumeProcessingIn(5 * time.Second), nil + } + sub := r.Client.Subscription(r.Subscription) + ctx, cFn := context.WithCancel(context.Background()) + + // Because emitters are not thread safe and synchronous Receive() behavior + // is deprecated, we have to collect messages in a goroutine and pipe them + // out through a channel. + messChan := make(chan *pubsub.Message, 1) + go func(sendch chan<- *pubsub.Message) { + err := sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) { + messChan <- m + }) + if (err != nil) && (err != context.Canceled) { + log.Errorf(ctx, "error reading from PubSub: %v, stopping processing", err) + cFn() + close(messChan) + } + }(messChan) + + // Give the goroutines time to start polling. + time.Sleep(5 * time.Second) + + for { + select { + case m, ok := <-messChan: + if !ok { + log.Debug(context.Background(), "stopping bundle processing") + return sdf.StopProcessing(), nil + } + r.ProcessedMessages = append(r.ProcessedMessages, m) + emit(beam.EventTime(m.PublishTime.UnixMilli()), m.Data) + default: + log.Debug(context.Background(), "cancelling receive context, scheduling resumption") + cFn() + return sdf.ResumeProcessingIn(10 * time.Second), nil + } + } + } +} + +// NativeRead reads messages from a PubSub topic in a streaming context, outputting +// received messages as a PCollection of byte slices. If the provided subscription +// name exists for the given topic, the DoFn will read from that subscription; otherwise, +// a new subscription with the given subscription name will be created and read from. +// +// This feature is experimental and subject to change, including its behavior and function signature. +// Please use the cross-language implementation Read() instead. +func NativeRead(s beam.Scope, project, topic, subscription string) beam.PCollection { + s = s.Scope("pubsubio.NativeRead") + + psRead, err := NewPubSubRead(context.Background(), project, topic, subscription) + if err != nil { + panic(err) + } + return beam.ParDo(s, psRead, beam.Impulse(s)) +} + +// PubSubWrite is a structural DoFn representing writes to a given PubSub topic. +type PubSubWrite struct { Review Comment: Same thing, don't export it if it's not necessary for package users to use it directly. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } + + for { + ok := rt.TryClaim(r.Subscription) + if !ok { + return sdf.ResumeProcessingIn(5 * time.Second), nil + } + sub := r.Client.Subscription(r.Subscription) + ctx, cFn := context.WithCancel(context.Background()) Review Comment: This ProcessElement method should accept a context.Context as the first parameter, and then use that as the basis of this cancelable context. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message Review Comment: I'm surprised these passed through, but if these are only needed at pipeline execution time, unexport the fields so they aren't attempted to be serialized. I doubt the client is meaningfully serializable. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } + + for { + ok := rt.TryClaim(r.Subscription) + if !ok { + return sdf.ResumeProcessingIn(5 * time.Second), nil + } + sub := r.Client.Subscription(r.Subscription) + ctx, cFn := context.WithCancel(context.Background()) + + // Because emitters are not thread safe and synchronous Receive() behavior + // is deprecated, we have to collect messages in a goroutine and pipe them + // out through a channel. + messChan := make(chan *pubsub.Message, 1) + go func(sendch chan<- *pubsub.Message) { + err := sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) { + messChan <- m + }) + if (err != nil) && (err != context.Canceled) { + log.Errorf(ctx, "error reading from PubSub: %v, stopping processing", err) + cFn() + close(messChan) + } + }(messChan) + + // Give the goroutines time to start polling. + time.Sleep(5 * time.Second) + + for { + select { + case m, ok := <-messChan: + if !ok { + log.Debug(context.Background(), "stopping bundle processing") + return sdf.StopProcessing(), nil + } + r.ProcessedMessages = append(r.ProcessedMessages, m) + emit(beam.EventTime(m.PublishTime.UnixMilli()), m.Data) + default: + log.Debug(context.Background(), "cancelling receive context, scheduling resumption") + cFn() + return sdf.ResumeProcessingIn(10 * time.Second), nil + } + } + } +} + +// NativeRead reads messages from a PubSub topic in a streaming context, outputting +// received messages as a PCollection of byte slices. If the provided subscription +// name exists for the given topic, the DoFn will read from that subscription; otherwise, +// a new subscription with the given subscription name will be created and read from. +// +// This feature is experimental and subject to change, including its behavior and function signature. +// Please use the cross-language implementation Read() instead. +func NativeRead(s beam.Scope, project, topic, subscription string) beam.PCollection { + s = s.Scope("pubsubio.NativeRead") + + psRead, err := NewPubSubRead(context.Background(), project, topic, subscription) + if err != nil { + panic(err) + } + return beam.ParDo(s, psRead, beam.Impulse(s)) +} + +// PubSubWrite is a structural DoFn representing writes to a given PubSub topic. +type PubSubWrite struct { + ProjectID string + Topic string + Client *pubsub.Client +} + +// ProcessElement takes a []byte element and publishes it to the provided PubSub +// topic. +func (w *PubSubWrite) ProcessElement(elm []byte) error { + // Initialize PubSub client if one has not been created already + if w.Client == nil { + client, err := pubsub.NewClient(context.Background(), w.ProjectID) + if err != nil { + return err + } + w.Client = client + } + top := w.Client.Topic(w.Topic) + + psMess := &pubsub.Message{Data: elm} + result := top.Publish(context.Background(), psMess) + if _, err := result.Get(context.Background()); err != nil { + return err + } + return nil +} + +// NewPubSubWrite inserts a write to a PubSub topic into the pipeline. +func NewPubSubWrite(ctx context.Context, projectID, topic string) (*PubSubWrite, error) { Review Comment: Unexport this please. ########## sdks/go/examples/native_wordcap/wordcap.go: ########## @@ -0,0 +1,79 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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. + +// native_wordcap is a toy streaming pipeline that uses PubSub. It +// does the following: +// (1) create a topic and publish a few messages to it +// (2) start a streaming pipeline that converts the messages to +// upper case and logs the result. +// +// NOTE: it only runs on Dataflow and must be manually cancelled. Review Comment: Technically, this one *doesn't* have to be run on dataflow! It's portable. Granted it'd be up to the user to have the environment to have whatever credentials present for lookup for the GCP permissions. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} Review Comment: Prefer nil for empty slices. Code shouldn't be making a distinction for nil and non-nil and it doesn't matter to append. ########## sdks/go/examples/native_wordcap/wordcap.go: ########## @@ -0,0 +1,79 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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. + +// native_wordcap is a toy streaming pipeline that uses PubSub. It Review Comment: Clarify that it ises the portable/native pubsub, to distinguish itself from the other wordcap. ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } + + for { + ok := rt.TryClaim(r.Subscription) + if !ok { + return sdf.ResumeProcessingIn(5 * time.Second), nil + } + sub := r.Client.Subscription(r.Subscription) + ctx, cFn := context.WithCancel(context.Background()) + + // Because emitters are not thread safe and synchronous Receive() behavior + // is deprecated, we have to collect messages in a goroutine and pipe them + // out through a channel. + messChan := make(chan *pubsub.Message, 1) + go func(sendch chan<- *pubsub.Message) { + err := sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) { + messChan <- m + }) + if (err != nil) && (err != context.Canceled) { + log.Errorf(ctx, "error reading from PubSub: %v, stopping processing", err) + cFn() + close(messChan) + } + }(messChan) + + // Give the goroutines time to start polling. + time.Sleep(5 * time.Second) + + for { + select { + case m, ok := <-messChan: + if !ok { + log.Debug(context.Background(), "stopping bundle processing") + return sdf.StopProcessing(), nil + } + r.ProcessedMessages = append(r.ProcessedMessages, m) + emit(beam.EventTime(m.PublishTime.UnixMilli()), m.Data) + default: + log.Debug(context.Background(), "cancelling receive context, scheduling resumption") + cFn() + return sdf.ResumeProcessingIn(10 * time.Second), nil + } + } + } +} + +// NativeRead reads messages from a PubSub topic in a streaming context, outputting +// received messages as a PCollection of byte slices. If the provided subscription +// name exists for the given topic, the DoFn will read from that subscription; otherwise, +// a new subscription with the given subscription name will be created and read from. +// +// This feature is experimental and subject to change, including its behavior and function signature. +// Please use the cross-language implementation Read() instead. +func NativeRead(s beam.Scope, project, topic, subscription string) beam.PCollection { + s = s.Scope("pubsubio.NativeRead") + + psRead, err := NewPubSubRead(context.Background(), project, topic, subscription) + if err != nil { + panic(err) + } + return beam.ParDo(s, psRead, beam.Impulse(s)) +} + +// PubSubWrite is a structural DoFn representing writes to a given PubSub topic. +type PubSubWrite struct { + ProjectID string + Topic string + Client *pubsub.Client +} + +// ProcessElement takes a []byte element and publishes it to the provided PubSub +// topic. +func (w *PubSubWrite) ProcessElement(elm []byte) error { + // Initialize PubSub client if one has not been created already + if w.Client == nil { + client, err := pubsub.NewClient(context.Background(), w.ProjectID) + if err != nil { + return err + } + w.Client = client + } + top := w.Client.Topic(w.Topic) + + psMess := &pubsub.Message{Data: elm} + result := top.Publish(context.Background(), psMess) + if _, err := result.Get(context.Background()); err != nil { Review Comment: Have a context.Context parameter and use that instead of context.Background() ########## sdks/go/examples/native_wordcap/nativepubsubio/native.go: ########## @@ -0,0 +1,236 @@ +// Licensed to the Apache Software Foundation (ASF) under one or more +// contributor license agreements. See the NOTICE file distributed with +// this work for additional information regarding copyright ownership. +// The ASF licenses this file to You 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 nativepubsubio contains a Golang implementation of streaming reads +// and writes to PubSub. This is not as fully featured as the cross-language +// pubsubio package present in the Beam Go repository and should not be used +// in place of it. +package nativepubsubio + +import ( + "context" + "errors" + "fmt" + "time" + + "cloud.google.com/go/pubsub" + "github.com/apache/beam/sdks/v2/go/pkg/beam" + "github.com/apache/beam/sdks/v2/go/pkg/beam/core/sdf" + "github.com/apache/beam/sdks/v2/go/pkg/beam/log" + "github.com/apache/beam/sdks/v2/go/pkg/beam/register" + "github.com/apache/beam/sdks/v2/go/pkg/beam/util/pubsubx" +) + +func init() { + register.DoFn4x2[beam.BundleFinalization, *sdf.LockRTracker, []byte, func(beam.EventTime, []byte), sdf.ProcessContinuation, error](&PubSubRead{}) + register.DoFn1x1[[]byte, error](&PubSubWrite{}) + register.Emitter2[beam.EventTime, []byte]() +} + +// PubSubRead is a structural DoFn representing a read from a given subscription ID. +type PubSubRead struct { + ProjectID string + Subscription string + Client *pubsub.Client + ProcessedMessages []*pubsub.Message +} + +// NewPubSubRead inserts an unbounded read from a PubSub topic into the pipeline. If an existing subscription +// is provided, the DoFn will read using that subscription; otherwise, a new subscription to the topic +// will be created using the provided subscription name. +func NewPubSubRead(ctx context.Context, projectID, topic, subscription string) (*PubSubRead, error) { + if topic == "" { + return nil, errors.New("please provide either a topic to read from") + } + client, err := pubsub.NewClient(ctx, projectID) + if err != nil { + return nil, err + } + + top := client.Topic(topic) + if ok, err := top.Exists(ctx); !ok || err != nil { + return nil, fmt.Errorf("failed to get topic; exists: %v, error: %v", ok, err) + } + sub, err := pubsubx.EnsureSubscription(ctx, client, topic, subscription) + if err != nil { + return nil, err + } + return &PubSubRead{ProjectID: projectID, Subscription: sub.ID()}, nil +} + +// CreateInitialRestriction() establishes the PubSub subscription ID as the +// initial restriction +func (r *PubSubRead) CreateInitialRestriction(_ []byte) string { + return r.Subscription +} + +// CreateTracker wraps the PubSub subscription ID in a StaticRTracker +// and applies a mutex via LockRTracker. +func (r *PubSubRead) CreateTracker(rest string) *sdf.LockRTracker { + return sdf.NewLockRTracker(NewSubscriptionRTracker(rest)) +} + +// RestrictionSize always returns 1.0, as the restriction is always 1 subscription. +func (r *PubSubRead) RestrictionSize(_ []byte, rest string) float64 { + return 1.0 +} + +// SplitRestriction is a no-op as the restriction cannot be split. +func (r *PubSubRead) SplitRestriction(_ []byte, rest string) []string { + return []string{rest} +} + +// ProcessElement initializes a PubSub client if one has not been created already, reads from the PubSub subscription, +// and emits elements as it reads them. If no messages are available, the DoFn will schedule itself to resume processing +// later. If polling the subscription returns an error, the error will be logged and the DoFn will not reschedule itself. +func (r *PubSubRead) ProcessElement(bf beam.BundleFinalization, rt *sdf.LockRTracker, _ []byte, emit func(beam.EventTime, []byte)) (sdf.ProcessContinuation, error) { + // Register finalization callback + bf.RegisterCallback(5*time.Minute, func() error { + for _, m := range r.ProcessedMessages { + m.Ack() + } + r.ProcessedMessages = []*pubsub.Message{} + return nil + }) + + // Initialize PubSub client if one has not been created already + if r.Client == nil { + client, err := pubsub.NewClient(context.Background(), r.ProjectID) + if err != nil { + return sdf.StopProcessing(), err + } + r.Client = client + } + + for { + ok := rt.TryClaim(r.Subscription) + if !ok { + return sdf.ResumeProcessingIn(5 * time.Second), nil + } + sub := r.Client.Subscription(r.Subscription) + ctx, cFn := context.WithCancel(context.Background()) + + // Because emitters are not thread safe and synchronous Receive() behavior + // is deprecated, we have to collect messages in a goroutine and pipe them + // out through a channel. + messChan := make(chan *pubsub.Message, 1) + go func(sendch chan<- *pubsub.Message) { + err := sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) { + messChan <- m + }) + if (err != nil) && (err != context.Canceled) { + log.Errorf(ctx, "error reading from PubSub: %v, stopping processing", err) + cFn() + close(messChan) + } + }(messChan) + + // Give the goroutines time to start polling. + time.Sleep(5 * time.Second) + + for { + select { + case m, ok := <-messChan: + if !ok { + log.Debug(context.Background(), "stopping bundle processing") + return sdf.StopProcessing(), nil + } + r.ProcessedMessages = append(r.ProcessedMessages, m) + emit(beam.EventTime(m.PublishTime.UnixMilli()), m.Data) + default: + log.Debug(context.Background(), "cancelling receive context, scheduling resumption") + cFn() + return sdf.ResumeProcessingIn(10 * time.Second), nil + } + } + } +} + +// NativeRead reads messages from a PubSub topic in a streaming context, outputting +// received messages as a PCollection of byte slices. If the provided subscription +// name exists for the given topic, the DoFn will read from that subscription; otherwise, +// a new subscription with the given subscription name will be created and read from. +// +// This feature is experimental and subject to change, including its behavior and function signature. +// Please use the cross-language implementation Read() instead. +func NativeRead(s beam.Scope, project, topic, subscription string) beam.PCollection { + s = s.Scope("pubsubio.NativeRead") + + psRead, err := NewPubSubRead(context.Background(), project, topic, subscription) + if err != nil { + panic(err) + } + return beam.ParDo(s, psRead, beam.Impulse(s)) +} + +// PubSubWrite is a structural DoFn representing writes to a given PubSub topic. +type PubSubWrite struct { + ProjectID string + Topic string + Client *pubsub.Client Review Comment: Unexport the fields that don't need to be serialized please. -- This is an automated message from the Apache Git Service. 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