Receive messages with delivery attempts

  namespace 
  
 pubsub 
  
 = 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 pubsub 
 ; 
 auto 
  
 sample 
  
 = 
  
 []( 
 pubsub 
 :: 
 Subscriber 
  
 subscriber 
 ) 
  
 { 
  
 return 
  
 subscriber 
 . 
 Subscribe 
 ( 
  
 [&]( 
 pubsub 
 :: 
 Message 
  
 const 
&  
 m 
 , 
  
 pubsub 
 :: 
 AckHandler 
  
 h 
 ) 
  
 { 
  
 std 
 :: 
 cout 
 << 
 "Received message " 
 << 
 m 
 << 
 " 
 \n 
 " 
 ; 
  
 std 
 :: 
 cout 
 << 
 "Delivery attempt: " 
 << 
 h 
 . 
 delivery_attempt 
 () 
 << 
 " 
 \n 
 " 
 ; 
  
 std 
 :: 
 move 
 ( 
 h 
 ). 
 ack 
 (); 
  
 PleaseIgnoreThisSimplifiesTestingTheSamples 
 (); 
  
 }); 
 }; 
 

  using 
  
  Google.Cloud.PubSub.V1 
 
 ; 
 using 
  
 System.Threading 
 ; 
 using 
  
 System.Threading.Tasks 
 ; 
 public 
  
 class 
  
 PullMessagesAsyncWithDeliveryAttemptsSample 
 { 
  
 public 
  
 async 
  
 Task<int> 
  
 PullMessagesAsyncWithDeliveryAttempts 
 ( 
 string 
  
 projectId 
 , 
  
 string 
  
 subscriptionId 
 , 
  
 bool 
  
 acknowledge 
 ) 
  
 { 
  
 // This is an existing subscription with a dead letter policy. 
  
  SubscriptionName 
 
  
 subscriptionName 
  
 = 
  
  SubscriptionName 
 
 . 
  FromProjectSubscription 
 
 ( 
 projectId 
 , 
  
 subscriptionId 
 ); 
  
  SubscriberClient 
 
  
 subscriber 
  
 = 
  
 await 
  
  SubscriberClient 
 
 . 
  CreateAsync 
 
 ( 
 subscriptionName 
 ); 
  
 int 
  
 deliveryAttempt 
  
 = 
  
 0 
 ; 
  
 Task 
  
 startTask 
  
 = 
  
 subscriber 
 . 
  StartAsync 
 
 (( 
  PubsubMessage 
 
  
 message 
 , 
  
 CancellationToken 
  
 cancel 
 ) 
  
 = 
>  
 { 
  
 string 
  
 text 
  
 = 
  
 message 
 . 
 Data 
 . 
 ToStringUtf8 
 (); 
  
 System 
 . 
 Console 
 . 
 WriteLine 
 ( 
 $"Delivery Attempt: {message.GetDeliveryAttempt()}" 
 ); 
  
 if 
  
 ( 
 message 
 . 
  GetDeliveryAttempt 
 
 () 
  
 != 
  
 null 
 ) 
  
 { 
  
 deliveryAttempt 
  
 = 
  
 message 
 . 
  GetDeliveryAttempt 
 
 (). 
 Value 
 ; 
  
 } 
  
 return 
  
 Task 
 . 
 FromResult 
 ( 
 acknowledge 
  
 ? 
  
  SubscriberClient 
 
 . 
  Reply 
 
 . 
  Ack 
 
  
 : 
  
  SubscriberClient 
 
 . 
  Reply 
 
 . 
  Nack 
 
 ); 
  
 }); 
  
 // Run for 7 seconds. 
  
 await 
  
 Task 
 . 
 Delay 
 ( 
 7000 
 ); 
  
 await 
  
 subscriber 
 . 
  StopAsync 
 
 ( 
 CancellationToken 
 . 
 None 
 ); 
  
 // Lets make sure that the start task finished successfully after the call to stop. 
  
 await 
  
 startTask 
 ; 
  
 return 
  
 deliveryAttempt 
 ; 
  
 } 
 } 
 

  import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "io" 
  
 "time" 
  
 "cloud.google.com/go/pubsub/v2" 
 ) 
 func 
  
 pullMsgsDeadLetterDeliveryAttempt 
 ( 
 w 
  
 io 
 . 
 Writer 
 , 
  
 projectID 
 , 
  
 subID 
  
 string 
 ) 
  
 error 
  
 { 
  
 // projectID := "my-project-id" 
  
 // subID := "my-sub" 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 pubsub 
 . 
 NewClient 
 ( 
 ctx 
 , 
  
 projectID 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "pubsub.NewClient: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 // Receive messages for 10 seconds, which simplifies testing. 
  
 // Comment this out in production, since `Receive` should 
  
 // be used as a long running operation. 
  
 ctx 
 , 
  
 cancel 
  
 := 
  
 context 
 . 
 WithTimeout 
 ( 
 ctx 
 , 
  
 10 
 * 
 time 
 . 
 Second 
 ) 
  
 defer 
  
 cancel 
 () 
  
 // client.Subscriber can be passed a subscription ID (e.g. "my-sub") or 
  
 // a fully qualified name (e.g. "projects/my-project/subscriptions/my-sub"). 
  
 // If a subscription ID is provided, the project ID from the client is used. 
  
 sub 
  
 := 
  
 client 
 . 
 Subscriber 
 ( 
 subID 
 ) 
  
 err 
  
 = 
  
 sub 
 . 
 Receive 
 ( 
 ctx 
 , 
  
 func 
 ( 
 _ 
  
 context 
 . 
 Context 
 , 
  
 msg 
  
 * 
 pubsub 
 . 
 Message 
 ) 
  
 { 
  
 // When dead lettering is enabled, the delivery attempt field is a pointer to the 
  
 // the number of times the service has attempted to delivery a message. 
  
 // Otherwise, the field is nil. 
  
 if 
  
 msg 
 . 
 DeliveryAttempt 
  
 != 
  
 nil 
  
 { 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "message: %s, delivery attempts: %d" 
 , 
  
 msg 
 . 
 Data 
 , 
  
 * 
 msg 
 . 
 DeliveryAttempt 
 ) 
  
 } 
  
 msg 
 . 
 Ack 
 () 
  
 }) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "got error in Receive: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 return 
  
 nil 
 } 
 

  import 
  
 com.google.cloud.pubsub.v1. AckReplyConsumer 
 
 ; 
 import 
  
 com.google.cloud.pubsub.v1. MessageReceiver 
 
 ; 
 import 
  
 com.google.cloud.pubsub.v1. Subscriber 
 
 ; 
 import 
  
 com.google.pubsub.v1. ProjectSubscriptionName 
 
 ; 
 import 
  
 com.google.pubsub.v1. PubsubMessage 
 
 ; 
 import 
  
 java.util.concurrent.TimeUnit 
 ; 
 import 
  
 java.util.concurrent.TimeoutException 
 ; 
 public 
  
 class 
 ReceiveMessagesWithDeliveryAttemptsExample 
  
 { 
  
 public 
  
 static 
  
 void 
  
 main 
 ( 
 String 
 ... 
  
 args 
 ) 
  
 throws 
  
 Exception 
  
 { 
  
 // TODO(developer): Replace these variables before running the sample. 
  
 String 
  
 projectId 
  
 = 
  
 "your-project-id" 
 ; 
  
 // This is an existing subscription with a dead letter policy. 
  
 String 
  
 subscriptionId 
  
 = 
  
 "your-subscription-id" 
 ; 
  
 ReceiveMessagesWithDeliveryAttemptsExample 
 . 
 receiveMessagesWithDeliveryAttemptsExample 
 ( 
  
 projectId 
 , 
  
 subscriptionId 
 ); 
  
 } 
  
 public 
  
 static 
  
 void 
  
 receiveMessagesWithDeliveryAttemptsExample 
 ( 
  
 String 
  
 projectId 
 , 
  
 String 
  
 subscriptionId 
 ) 
  
 { 
  
  ProjectSubscriptionName 
 
  
 subscriptionName 
  
 = 
  
  ProjectSubscriptionName 
 
 . 
 of 
 ( 
 projectId 
 , 
  
 subscriptionId 
 ); 
  
 // Instantiate an asynchronous message receiver. 
  
  MessageReceiver 
 
  
 receiver 
  
 = 
  
 new 
  
  MessageReceiver 
 
 () 
  
 { 
  
 @Override 
  
 public 
  
 void 
  
 receiveMessage 
 ( 
  PubsubMessage 
 
  
 message 
 , 
  
  AckReplyConsumer 
 
  
 consumer 
 ) 
  
 { 
  
 // Handle incoming message, then ack the received message. 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "Id: " 
  
 + 
  
 message 
 . 
  getMessageId 
 
 ()); 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "Data: " 
  
 + 
  
 message 
 . 
  getData 
 
 (). 
 toStringUtf8 
 ()); 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "Delivery Attempt: " 
  
 + 
  
  Subscriber 
 
 . 
 getDeliveryAttempt 
 ( 
 message 
 )); 
  
 consumer 
 . 
  ack 
 
 (); 
  
 } 
  
 }; 
  
  Subscriber 
 
  
 subscriber 
  
 = 
  
 null 
 ; 
  
 try 
  
 { 
  
 subscriber 
  
 = 
  
  Subscriber 
 
 . 
 newBuilder 
 ( 
 subscriptionName 
 , 
  
 receiver 
 ). 
 build 
 (); 
  
 // Start the subscriber. 
  
 subscriber 
 . 
  startAsync 
 
 (). 
 awaitRunning 
 (); 
  
 System 
 . 
 out 
 . 
 printf 
 ( 
 "Listening for messages on %s:\n" 
 , 
  
 subscriptionName 
 . 
  toString 
 
 ()); 
  
 // Allow the subscriber to run for 30s unless an unrecoverable error occurs. 
  
 subscriber 
 . 
 awaitTerminated 
 ( 
 30 
 , 
  
 TimeUnit 
 . 
 SECONDS 
 ); 
  
 } 
  
 catch 
  
 ( 
 TimeoutException 
  
 timeoutException 
 ) 
  
 { 
  
 // Shut down the subscriber after 30s. Stop receiving messages. 
  
 subscriber 
 . 
 stopAsync 
 (); 
  
 } 
  
 } 
 } 
 

  use Google\Cloud\PubSub\Message; 
 use Google\Cloud\PubSub\PubSubClient; 
 /** 
 * Get the delivery attempt from a pulled message. 
 * 
 * @param string $projectId  The Google project ID. 
 * @param string $topicName  The Pub/Sub topic name. 
 * @param string $subscriptionName  The Pub/Sub subscription name. 
 * @param string $message The contents of a pubsub message data field. 
 */ 
 function dead_letter_delivery_attempt($projectId, $topicName, $subscriptionName, $message) 
 { 
 $pubsub = new PubSubClient([ 
 'projectId' => $projectId, 
 ]); 
 $topic = $pubsub->topic($topicName); 
 // publish test message 
 $topic->publish(new Message([ 
 'data' => $message 
 ])); 
 $subscription = $topic->subscription($subscriptionName); 
 $messages = $subscription->pull(); 
 foreach ($messages as $message) { 
 printf('Received message %s' . PHP_EOL, $message->data()); 
 printf('Delivery attempt %d' . PHP_EOL, $message->deliveryAttempt()); 
 } 
 print('Done' . PHP_EOL); 
 } 
 

  # subscription_id = "your-subscription-id" 
 pubsub 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  PubSub 
 
 . 
  new 
 
 subscriber 
  
 = 
  
 pubsub 
 . 
  subscriber 
 
  
 subscription_id 
 subscriber 
 . 
 pull 
 ( 
 immediate 
 : 
  
 false 
 ) 
 . 
 each 
  
 do 
  
 | 
 message 
 | 
  
 puts 
  
 "Received message: 
 #{ 
 message 
 . 
 data 
 } 
 " 
  
 puts 
  
 "Delivery Attempt: 
 #{ 
 message 
 . 
 delivery_attempt 
 } 
 " 
  
 message 
 . 
  acknowledge! 
 
 end