[GitHub] [pulsar-client-node] BewareMyPower commented on a diff in pull request #309: [Fix] Fix message listener doesn't respect receiver queue size

["BewareMyPower (via GitHub)" <gi...@apache.org>]

BewareMyPower commented on code in PR #309:
URL: https://github.com/apache/pulsar-client-node/pull/309#discussion_r1157505847


##########
src/Consumer.cc:
##########
@@ -82,9 +96,15 @@ void MessageListener(pulsar_consumer_t *rawConsumer, pulsar_message_t *rawMessag
     return;
   }
 
-  MessageListenerProxyData *dataPtr = new MessageListenerProxyData(cMessage, consumer);
+  std::promise<void> promise;
+  std::future<void> future = promise.get_future();
+  MessageListenerProxyData *dataPtr =
+      new MessageListenerProxyData(cMessage, consumer, [&]() { promise.set_value(); });
   listenerCallback->callback.BlockingCall(dataPtr, MessageListenerProxy);
   listenerCallback->callback.Release();
+
+  future.wait();
+  delete dataPtr;

Review Comment:
   It's better not to use `delete` directly, use `std::unique_ptr`.



##########
src/Consumer.cc:
##########
@@ -55,21 +56,34 @@ void Consumer::Init(Napi::Env env, Napi::Object exports) {
 struct MessageListenerProxyData {
   std::shared_ptr<pulsar_message_t> cMessage;
   Consumer *consumer;
+  std::function<void(void)> callback;
 
-  MessageListenerProxyData(std::shared_ptr<pulsar_message_t> cMessage, Consumer *consumer)
-      : cMessage(cMessage), consumer(consumer) {}
+  MessageListenerProxyData(std::shared_ptr<pulsar_message_t> cMessage, Consumer *consumer,
+                           std::function<void(void)> callback)
+      : cMessage(cMessage), consumer(consumer), callback(callback) {}
 };
 
 void MessageListenerProxy(Napi::Env env, Napi::Function jsCallback, MessageListenerProxyData *data) {
   Napi::Object msg = Message::NewInstance({}, data->cMessage);
   Consumer *consumer = data->consumer;
-  delete data;

Review Comment:
   I think we should still delete the data. Replace this line with `std::unique_ptr<MessageListenerProxyData*> data_guard` is a common used RAII solution.



##########
src/Consumer.cc:
##########
@@ -82,9 +96,15 @@ void MessageListener(pulsar_consumer_t *rawConsumer, pulsar_message_t *rawMessag
     return;
   }
 
-  MessageListenerProxyData *dataPtr = new MessageListenerProxyData(cMessage, consumer);
+  std::promise<void> promise;
+  std::future<void> future = promise.get_future();
+  MessageListenerProxyData *dataPtr =
+      new MessageListenerProxyData(cMessage, consumer, [&]() { promise.set_value(); });

Review Comment:
   ```suggestion
         new MessageListenerProxyData(cMessage, consumer, [&promise]() { promise.set_value(); });
   ```
   
   Capture the specific value or reference instead of capturing all values or references.



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