Publish with concurrency control

  namespace 
  
 pubsub 
  
 = 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 pubsub 
 ; 
 using 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 future 
 ; 
 using 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 GrpcBackgroundThreadPoolSizeOption 
 ; 
 using 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 Options 
 ; 
 using 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 StatusOr 
 ; 
 []( 
 std 
 :: 
 string 
  
 project_id 
 , 
  
 std 
 :: 
 string 
  
 topic_id 
 ) 
  
 { 
  
 auto 
  
 topic 
  
 = 
  
 pubsub 
 :: 
 Topic 
 ( 
 std 
 :: 
 move 
 ( 
 project_id 
 ), 
  
 std 
 :: 
 move 
 ( 
 topic_id 
 )); 
  
 // Override the default number of background (I/O) threads. By default the 
  
 // library uses `std::thread::hardware_concurrency()` threads. 
  
 auto 
  
 options 
  
 = 
  
 Options 
 {}. 
 set<GrpcBackgroundThreadPoolSizeOption> 
 ( 
 8 
 ); 
  
 auto 
  
 publisher 
  
 = 
  
 pubsub 
 :: 
 Publisher 
 ( 
  
 pubsub 
 :: 
 MakePublisherConnection 
 ( 
 std 
 :: 
 move 
 ( 
 topic 
 ), 
  
 std 
 :: 
 move 
 ( 
 options 
 ))); 
  
 std 
 :: 
 vector<future<void> 
>  
 ids 
 ; 
  
 for 
  
 ( 
 char 
  
 const 
 * 
  
 data 
  
 : 
  
 { 
 "1" 
 , 
  
 "2" 
 , 
  
 "3" 
 , 
  
 "go!" 
 }) 
  
 { 
  
 ids 
 . 
 push_back 
 ( 
  
 publisher 
 . 
 Publish 
 ( 
 pubsub 
 :: 
 MessageBuilder 
 (). 
 SetData 
 ( 
 data 
 ). 
 Build 
 ()) 
  
 . 
 then 
 ([ 
 data 
 ]( 
 future<StatusOr<std 
 :: 
 string 
>>  
 f 
 ) 
  
 { 
  
 auto 
  
 s 
  
 = 
  
 f 
 . 
 get 
 (); 
  
 if 
  
 ( 
 ! 
 s 
 ) 
  
 return 
 ; 
  
 std 
 :: 
 cout 
 << 
 "Sent '" 
 << 
 data 
 << 
 "' (" 
 << 
 * 
 s 
 << 
 ") 
 \n 
 " 
 ; 
  
 })); 
  
 } 
  
 publisher 
 . 
 Flush 
 (); 
  
 // Block until they are actually sent. 
  
 for 
  
 ( 
 auto 
&  
 id 
  
 : 
  
 ids 
 ) 
  
 id 
 . 
 get 
 (); 
 } 
 

  import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "io" 
  
 "cloud.google.com/go/pubsub/v2" 
 ) 
 func 
  
 publishSingleGoroutine 
 ( 
 w 
  
 io 
 . 
 Writer 
 , 
  
 projectID 
 , 
  
 topicID 
 , 
  
 msg 
  
 string 
 ) 
  
 error 
  
 { 
  
 // projectID := "my-project-id" 
  
 // topicID := "my-topic" 
  
 // msg := "Hello World" 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 pubsub 
 . 
 NewClient 
 ( 
 ctx 
 , 
  
 projectID 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "pubsub.NewClient: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 // client.Publisher can be passed a topic ID (e.g. "my-topic") or 
  
 // a fully qualified name (e.g. "projects/my-project/topics/my-topic"). 
  
 // If a topic ID is provided, the project ID from the client is used. 
  
 publisher 
  
 := 
  
 client 
 . 
 Publisher 
 ( 
 topicID 
 ) 
  
 publisher 
 . 
 PublishSettings 
 . 
 NumGoroutines 
  
 = 
  
 1 
  
 result 
  
 := 
  
 publisher 
 . 
 Publish 
 ( 
 ctx 
 , 
  
& pubsub 
 . 
 Message 
 { 
 Data 
 : 
  
 [] 
 byte 
 ( 
 msg 
 )}) 
  
 // Block until the result is returned and a server-generated 
  
 // ID is returned for the published message. 
  
 id 
 , 
  
 err 
  
 := 
  
 result 
 . 
 Get 
 ( 
 ctx 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "Get: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Published a message; msg ID: %v\n" 
 , 
  
 id 
 ) 
  
 return 
  
 nil 
 } 
 

  import 
  
 com.google.api.core. ApiFuture 
 
 ; 
 import 
  
 com.google.api.core. ApiFutures 
 
 ; 
 import 
  
 com.google.api.gax.core. ExecutorProvider 
 
 ; 
 import 
  
 com.google.api.gax.core. InstantiatingExecutorProvider 
 
 ; 
 import 
  
 com.google.cloud.pubsub.v1. Publisher 
 
 ; 
 import 
  
 com.google.protobuf. ByteString 
 
 ; 
 import 
  
 com.google.pubsub.v1. PubsubMessage 
 
 ; 
 import 
  
 com.google.pubsub.v1. TopicName 
 
 ; 
 import 
  
 java.io.IOException 
 ; 
 import 
  
 java.util.ArrayList 
 ; 
 import 
  
 java.util.List 
 ; 
 import 
  
 java.util.concurrent.ExecutionException 
 ; 
 import 
  
 java.util.concurrent.TimeUnit 
 ; 
 public 
  
 class 
 PublishWithConcurrencyControlExample 
  
 { 
  
 public 
  
 static 
  
 void 
  
 main 
 ( 
 String 
 ... 
  
 args 
 ) 
  
 throws 
  
 Exception 
  
 { 
  
 // TODO(developer): Replace these variables before running the sample. 
  
 String 
  
 projectId 
  
 = 
  
 "your-project-id" 
 ; 
  
 String 
  
 topicId 
  
 = 
  
 "your-topic-id" 
 ; 
  
 publishWithConcurrencyControlExample 
 ( 
 projectId 
 , 
  
 topicId 
 ); 
  
 } 
  
 public 
  
 static 
  
 void 
  
 publishWithConcurrencyControlExample 
 ( 
 String 
  
 projectId 
 , 
  
 String 
  
 topicId 
 ) 
  
 throws 
  
 IOException 
 , 
  
 ExecutionException 
 , 
  
 InterruptedException 
  
 { 
  
  TopicName 
 
  
 topicName 
  
 = 
  
  TopicName 
 
 . 
 of 
 ( 
 projectId 
 , 
  
 topicId 
 ); 
  
  Publisher 
 
  
 publisher 
  
 = 
  
 null 
 ; 
  
 List<ApiFuture<String> 
>  
 messageIdFutures 
  
 = 
  
 new 
  
 ArrayList 
<> (); 
  
 try 
  
 { 
  
 // Provides an executor service for processing messages. The default 
  
 // `executorProvider` used by the publisher has a default thread count of 
  
 // 5 * the number of processors available to the Java virtual machine. 
  
  ExecutorProvider 
 
  
 executorProvider 
  
 = 
  
  InstantiatingExecutorProvider 
 
 . 
 newBuilder 
 (). 
  setExecutorThreadCount 
 
 ( 
 4 
 ). 
 build 
 (); 
  
 // `setExecutorProvider` configures an executor for the publisher. 
  
 publisher 
  
 = 
  
  Publisher 
 
 . 
 newBuilder 
 ( 
 topicName 
 ). 
 setExecutorProvider 
 ( 
 executorProvider 
 ). 
 build 
 (); 
  
 // schedule publishing one message at a time : messages get automatically batched 
  
 for 
  
 ( 
 int 
  
 i 
  
 = 
  
 0 
 ; 
  
 i 
 < 
 100 
 ; 
  
 i 
 ++ 
 ) 
  
 { 
  
 String 
  
 message 
  
 = 
  
 "message " 
  
 + 
  
 i 
 ; 
  
  ByteString 
 
  
 data 
  
 = 
  
  ByteString 
 
 . 
  copyFromUtf8 
 
 ( 
 message 
 ); 
  
  PubsubMessage 
 
  
 pubsubMessage 
  
 = 
  
  PubsubMessage 
 
 . 
 newBuilder 
 (). 
  setData 
 
 ( 
 data 
 ). 
 build 
 (); 
  
 // Once published, returns a server-assigned message id (unique within the topic) 
  
 ApiFuture<String> 
  
 messageIdFuture 
  
 = 
  
  publish 
 
er . 
  publish 
 
 ( 
 pubsubMessage 
 ); 
  
 messageIdFutures 
 . 
 add 
 ( 
 messageIdFuture 
 ); 
  
 } 
  
 } 
  
 finally 
  
 { 
  
 // Wait on any pending publish requests. 
  
 List<String> 
  
 messageIds 
  
 = 
  
  ApiFutures 
 
 . 
  allAsList 
 
 ( 
 messageIdFutures 
 ). 
 get 
 (); 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "Published " 
  
 + 
  
 messageIds 
 . 
 size 
 () 
  
 + 
  
 " messages with concurrency control." 
 ); 
  
 if 
  
 ( 
 publisher 
  
 != 
  
 null 
 ) 
  
 { 
  
 // When finished with the publisher, shutdown to free up resources. 
  
 publisher 
 . 
  shutdown 
 
 (); 
  
 publisher 
 . 
  awaitTermination 
 
 ( 
 1 
 , 
  
 TimeUnit 
 . 
 MINUTES 
 ); 
  
 } 
  
 } 
  
 } 
 } 
 

  # topic_id = "your-topic-id" 
 pubsub 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  PubSub 
 
 . 
  new 
 
 publisher 
  
 = 
  
 pubsub 
 . 
  publisher 
 
  
 topic_id 
 , 
  
 async 
 : 
  
 { 
  
 threads 
 : 
  
 { 
  
 # Use exactly one thread for publishing message and exactly one thread 
  
 # for executing callbacks 
  
 publish 
 : 
  
 1 
 , 
  
 callback 
 : 
  
 1 
  
 } 
 } 
 publisher 
 . 
  publish_async 
 
  
 "This is a test message." 
  
 do 
  
 | 
 result 
 | 
  
 raise 
  
 "Failed to publish the message." 
  
 unless 
  
 result 
 . 
 succeeded? 
  
 puts 
  
 "Message published asynchronously." 
 end 
 # Stop the async_publisher to send all queued messages immediately. 
 publisher 
 . 
  async_publisher 
 
 . 
 stop 
 . 
 wait!