Fix ack failure on message listener in multi topics consumer (#447)

Author: nkurihar

lib/ConsumerImpl.cc

@@ -292,11 +292,7 @@ void ConsumerImpl::sendFlowPermitsToBroker(const ClientConnectionPtr& cnx, int n
 Result ConsumerImpl::handleCreateConsumer(const ClientConnectionPtr& cnx, Result result) {
     Result handleResult = ResultOk;
 
-    static bool firstTime = true;
     if (result == ResultOk) {
-        if (firstTime) {
-            firstTime = false;
-        }
         LOG_INFO(getName() << "Created consumer on broker " << cnx->cnxString());
         {
             Lock lock(mutex_);
@@ -313,12 +309,10 @@ Result ConsumerImpl::handleCreateConsumer(const ClientConnectionPtr& cnx, Result
         }
 
         LOG_DEBUG(getName() << "Send initial flow permits: " << config_.getReceiverQueueSize());
-        if (consumerTopicType_ == NonPartitioned || !firstTime) {
-            if (config_.getReceiverQueueSize() != 0) {
-                sendFlowPermitsToBroker(cnx, config_.getReceiverQueueSize());
-            } else if (messageListener_) {
-                sendFlowPermitsToBroker(cnx, 1);
-            }
+        if (config_.getReceiverQueueSize() != 0) {
+            sendFlowPermitsToBroker(cnx, config_.getReceiverQueueSize());
+        } else if (messageListener_) {
+            sendFlowPermitsToBroker(cnx, 1);
         }
         consumerCreatedPromise_.setValue(get_shared_this_ptr());
     } else {

lib/MultiTopicsConsumerImpl.cc

@@ -149,6 +149,11 @@ void MultiTopicsConsumerImpl::handleOneTopicSubscribed(Result result, Consumer c
         if (state_.compare_exchange_strong(state, Ready)) {
             LOG_INFO("Successfully Subscribed to Topics");
             multiTopicsConsumerCreatedPromise_.setValue(get_shared_this_ptr());
+            // Now all child topics are successfully subscribed, start messageListeners
+            if (messageListener_ && !conf_.isStartPaused()) {
+                LOG_INFO("Start messageListeners");
+                resumeMessageListener();
+            }
         } else {
             LOG_ERROR("Unable to create Consumer - " << consumerStr_ << " Error - " << result);
             // unsubscribed all of the successfully subscribed partitioned consumers
@@ -205,6 +210,11 @@ void MultiTopicsConsumerImpl::subscribeTopicPartitions(int numPartitions, TopicN
                                                        ConsumerSubResultPromisePtr topicSubResultPromise) {
     std::shared_ptr<ConsumerImpl> consumer;
     ConsumerConfiguration config = conf_.clone();
+    // Pause messageListener until all child topics are subscribed.
+    // Otherwise messages may be acked before the parent consumer gets "Ready", causing ack failures.
+    if (messageListener_) {
+        config.setStartPaused(true);
+    }
     auto client = client_.lock();
     if (!client) {
         topicSubResultPromise->setFailed(ResultAlreadyClosed);