packagemainimport("context""flag""fmt""log""sync/atomic""time""cloud.google.com/go/pubsub""cloud.google.com/go/pubsublite/pscompat")funcmain(){// NOTE: Set these flags for an existing Pub/Sub Lite subscription containing// published messages when running this sample.projectID:=flag.String("project_id","","Cloud Project ID")zone:=flag.String("zone","","Cloud Zone where the topic resides, e.g. us-central1-a")subscriptionID:=flag.String("subscription_id","","Existing Pub/Sub Lite subscription")timeout:=flag.Duration("timeout",90*time.Second,"The duration to receive messages")flag.Parse()ctx:=context.Background()subscriptionPath:=fmt.Sprintf("projects/%s/locations/%s/subscriptions/%s",*projectID,*zone,*subscriptionID)// Configure flow control settings. These settings apply per partition.// The message stream is paused based on the maximum size or number of// messages that the subscriber has already received, whichever condition is// met first.settings:=pscompat.ReceiveSettings{// 10 MiB. Must be greater than the allowed size of the largest message// (1 MiB).MaxOutstandingBytes:10*1024*1024,// 1,000 outstanding messages. Must be > 0.MaxOutstandingMessages:1000,}// Create the subscriber client.subscriber,err:=pscompat.NewSubscriberClientWithSettings(ctx,subscriptionPath,settings)iferr!=nil{log.Fatalf("pscompat.NewSubscriberClientWithSettings error: %v",err)}// Listen for messages until the timeout expires.log.Printf("Listening to messages on %s for %v...\n",subscriptionPath,*timeout)cctx,cancel:=context.WithTimeout(ctx,*timeout)defercancel()varreceiveCountint32// Receive blocks until the context is cancelled or an error occurs.iferr:=subscriber.Receive(cctx,func(ctxcontext.Context,msg*pubsub.Message){// NOTE: May be called concurrently; synchronize access to shared memory.atomic.AddInt32(&receiveCount,1)// Metadata decoded from the message ID contains the partition and offset.metadata,err:=pscompat.ParseMessageMetadata(msg.ID)iferr!=nil{log.Fatalf("Failed to parse %q: %v",msg.ID,err)}fmt.Printf("Received (partition=%d, offset=%d): %s\n",metadata.Partition,metadata.Offset,string(msg.Data))msg.Ack()});err!=nil{log.Fatalf("SubscriberClient.Receive error: %v",err)}fmt.Printf("Received %d messages\n",receiveCount)}

importcom.google.api.gax.rpc.ApiException;importcom.google.cloud.pubsub.v1.AckReplyConsumer;importcom.google.cloud.pubsub.v1.MessageReceiver;importcom.google.cloud.pubsublite.CloudRegion;importcom.google.cloud.pubsublite.CloudRegionOrZone;importcom.google.cloud.pubsublite.CloudZone;importcom.google.cloud.pubsublite.MessageMetadata;importcom.google.cloud.pubsublite.ProjectNumber;importcom.google.cloud.pubsublite.SubscriptionName;importcom.google.cloud.pubsublite.SubscriptionPath;importcom.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;importcom.google.cloud.pubsublite.cloudpubsub.MessageTransforms;importcom.google.cloud.pubsublite.cloudpubsub.Subscriber;importcom.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;importcom.google.protobuf.Timestamp;importcom.google.pubsub.v1.PubsubMessage;importjava.util.concurrent.TimeUnit;importjava.util.concurrent.TimeoutException;publicclassSubscriberExample{publicstaticvoidmain(String...args)throwsException{// TODO(developer): Replace these variables before running the sample.StringcloudRegion="your-cloud-region";charzoneId='b';// Choose an existing subscription for the subscribe example to work.StringsubscriptionId="your-subscription-id";longprojectNumber=Long.parseLong("123456789");// True if using a regional location. False if using a zonal location.// https://cloud.google.com/pubsub/lite/docs/topicsbooleanregional=false;subscriberExample(cloudRegion,zoneId,projectNumber,subscriptionId,regional);}publicstaticvoidsubscriberExample(StringcloudRegion,charzoneId,longprojectNumber,StringsubscriptionId,booleanregional)throwsApiException{CloudRegionOrZonelocation;if(regional){location=CloudRegionOrZone.of(CloudRegion.of(cloudRegion));}else{location=CloudRegionOrZone.of(CloudZone.of(CloudRegion.of(cloudRegion),zoneId));}SubscriptionPathsubscriptionPath=SubscriptionPath.newBuilder().setLocation(location).setProject(ProjectNumber.of(projectNumber)).setName(SubscriptionName.of(subscriptionId)).build();// The message stream is paused based on the maximum size or number of messages that the// subscriber has already received, whichever condition is met first.FlowControlSettingsflowControlSettings=FlowControlSettings.builder()// 10 MiB. Must be greater than the allowed size of the largest message (1 MiB)..setBytesOutstanding(10*1024*1024L)// 1,000 outstanding messages. Must be >0..setMessagesOutstanding(1000L).build();MessageReceiverreceiver=(PubsubMessagemessage,AckReplyConsumerconsumer)->{System.out.println("Id : "+MessageMetadata.decode(message.getMessageId()));System.out.println("Data : "+message.getData().toStringUtf8());System.out.println("Ordering key : "+message.getOrderingKey());System.out.println("Attributes : ");message.getAttributesMap().forEach((key,value)->{if(key==MessageTransforms.PUBSUB_LITE_EVENT_TIME_TIMESTAMP_PROTO){Timestampts=MessageTransforms.decodeAttributeEventTime(value);System.out.println(key+" = "+ts.toString());}else{System.out.println(key+" = "+value);}});// Acknowledge the message.consumer.ack();};SubscriberSettingssubscriberSettings=SubscriberSettings.newBuilder().setSubscriptionPath(subscriptionPath).setReceiver(receiver)// Flow control settings are set at the partition level..setPerPartitionFlowControlSettings(flowControlSettings).build();Subscribersubscriber=Subscriber.create(subscriberSettings);// Start the subscriber. Upon successful starting, its state will become RUNNING.subscriber.startAsync().awaitRunning();System.out.println("Listening to messages on "+subscriptionPath.toString()+"...");try{System.out.println(subscriber.state());// Wait 90 seconds for the subscriber to reach TERMINATED state. If it encounters// unrecoverable errors before then, its state will change to FAILED and an// IllegalStateException will be thrown.subscriber.awaitTerminated(90,TimeUnit.SECONDS);}catch(TimeoutExceptiont){// Shut down the subscriber. This will change the state of the subscriber to TERMINATED.subscriber.stopAsync().awaitTerminated();System.out.println("Subscriber is shut down: "+subscriber.state());}}}

fromconcurrent.futures._baseimportTimeoutErrorfromgoogle.pubsub_v1importPubsubMessagefromgoogle.cloud.pubsublite.cloudpubsubimportSubscriberClientfromgoogle.cloud.pubsublite.typesimport(CloudRegion,CloudZone,FlowControlSettings,MessageMetadata,SubscriptionPath,)# TODO(developer):# project_number = 1122334455# cloud_region = "us-central1"# zone_id = "a"# subscription_id = "your-subscription-id"# timeout = 90# regional = Trueifregional:location=CloudRegion(cloud_region)else:location=CloudZone(CloudRegion(cloud_region),zone_id)subscription_path=SubscriptionPath(project_number,location,subscription_id)# Configure when to pause the message stream for more incoming messages based on the# maximum size or number of messages that a single-partition subscriber has received,# whichever condition is met first.per_partition_flow_control_settings=FlowControlSettings(# 1,000 outstanding messages. Must be >0.messages_outstanding=1000,# 10 MiB. Must be greater than the allowed size of the largest message (1 MiB).bytes_outstanding=10*1024*1024,)defcallback(message:PubsubMessage):message_data=message.data.decode("utf-8")metadata=MessageMetadata.decode(message.message_id)print(f"Received{message_data} of ordering key{message.ordering_key} with id{metadata}.")message.ack()# SubscriberClient() must be used in a `with` block or have __enter__() called before use.withSubscriberClient()assubscriber_client:streaming_pull_future=subscriber_client.subscribe(subscription_path,callback=callback,per_partition_flow_control_settings=per_partition_flow_control_settings,)print(f"Listening for messages on{str(subscription_path)}...")try:streaming_pull_future.result(timeout=timeout)exceptTimeoutErrororKeyboardInterrupt:streaming_pull_future.cancel()assertstreaming_pull_future.done()