[GitHub] [pulsar-client-cpp] shibd commented on a diff in pull request #139: [feat] Support Dead Letter Topic.

[GitBox <gi...@apache.org>]

shibd commented on code in PR #139:
URL: https://github.com/apache/pulsar-client-cpp/pull/139#discussion_r1063259612


##########
lib/ConsumerImpl.cc:
##########
@@ -1526,4 +1577,96 @@ void ConsumerImpl::cancelTimers() noexcept {
     checkExpiredChunkedTimer_->cancel(ec);
 }
 
+void ConsumerImpl::processPossibleToDLQ(const MessageId& messageId, ProcessDLQCallBack cb) {
+    auto messages = possibleSendToDeadLetterTopicMessages_.find(messageId);
+    if (!messages) {
+        cb(false);
+        return;
+    }
+
+    // Initialize deadLetterProducer_
+    if (!deadLetterProducer_) {
+        Lock createLock(createProducerLock_);
+        if (!deadLetterProducer_) {
+            deadLetterProducer_ = std::make_shared<Promise<Result, Producer>>();
+            ProducerConfiguration producerConfiguration;
+            producerConfiguration.setSchema(config_.getSchema());
+            producerConfiguration.setBlockIfQueueFull(false);
+            if (!deadLetterPolicy_.getInitialSubscriptionName().empty()) {
+                producerConfiguration.setInitialSubscriptionName(
+                    deadLetterPolicy_.getInitialSubscriptionName());
+            }
+            ClientImplPtr client = client_.lock();
+            if (client) {
+                client->createProducerAsync(
+                    deadLetterPolicy_.getDeadLetterTopic(), producerConfiguration,
+                    [this](Result res, Producer producer) {
+                        if (res == ResultOk) {
+                            deadLetterProducer_->setValue(producer);
+                        } else {
+                            LOG_ERROR("Dead letter producer create exception with topic: "
+                                      << deadLetterPolicy_.getDeadLetterTopic() << " ex: " << res);
+                            deadLetterProducer_.reset();
+                        }
+                    });
+            } else {
+                LOG_WARN(getName() << "Client is destroyed and cannot create dead letter producer.");
+            }
+        }
+        createLock.unlock();
+    }
+
+    for (const auto& message : messages.value()) {
+        auto self = get_shared_this_ptr();
+        deadLetterProducer_->getFuture().addListener([self, message, cb](Result res, Producer producer) {
+            auto originMessageId = message.getMessageId();
+            std::stringstream originMessageIdStr;
+            originMessageIdStr << originMessageId;
+            MessageBuilder msgBuilder;
+            msgBuilder.setAllocatedContent(const_cast<void*>(message.getData()), message.getLength())
+                .setProperties(message.getProperties())
+                .setProperty(PROPERTY_ORIGIN_MESSAGE_ID, originMessageIdStr.str())
+                .setProperty(SYSTEM_PROPERTY_REAL_TOPIC, message.getTopicName());
+            if (message.hasPartitionKey()) {
+                msgBuilder.setPartitionKey(message.getPartitionKey());
+            }
+            if (message.hasOrderingKey()) {
+                msgBuilder.setOrderingKey(message.getOrderingKey());
+            }
+            producer.sendAsync(msgBuilder.build(), [self, originMessageId, cb](Result res,

Review Comment:
   Make sense.



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