src/main/cpp/rocketmq/ConsumeTask.cpp

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "ConsumeTask.h"

#include "LoggerImpl.h"

ROCKETMQ_NAMESPACE_BEGIN

ConsumeTask::ConsumeTask(ConsumeMessageServiceWeakPtr service,
                         std::weak_ptr<ProcessQueue> process_queue,
                         MessageConstSharedPtr message)
    : service_(service), process_queue_(std::move(process_queue)) {
  messages_.emplace_back(message);
}

ConsumeTask::ConsumeTask(ConsumeMessageServiceWeakPtr service,
                         std::weak_ptr<ProcessQueue> process_queue,
                         std::vector<MessageConstSharedPtr> messages)
    : service_(service), process_queue_(std::move(process_queue)), messages_(std::move(messages)) {
  fifo_ = messages_.size() > 1;
}

void ConsumeTask::pop() {
  assert(!messages_.empty());
  auto process_queue = process_queue_.lock();
  if (!process_queue) {
    return;
  }

  process_queue->release(messages_[0]->body().size());

  messages_.erase(messages_.begin());
}

void ConsumeTask::submit() {
  auto svc = service_.lock();
  if (!svc) {
    return;
  }
  svc->submit(shared_from_this());
}

void ConsumeTask::schedule() {
  auto svc = service_.lock();
  if (!svc) {
    return;
  }

  svc->schedule(shared_from_this(), std::chrono::seconds(1));
}

void ConsumeTask::onAck(std::shared_ptr<ConsumeTask> task, const std::error_code& ec) {
  if (task->fifo_ && ec) {
    auto service = task->service_.lock();
    task->next_step_ = NextStep::Ack;
    task->schedule();
  } else {
    // If it is not FIFO or ack operation succeeded
    task->pop();
    task->next_step_ = NextStep::Consume;
  }
  task->submit();
}

void ConsumeTask::onNack(std::shared_ptr<ConsumeTask> task, const std::error_code& ec) {
  assert(!task->fifo_);
  assert(!task->messages_.empty());
  if (ec) {
    SPDLOG_WARN("Failed to nack message[message-id={}]. Cause: {}", task->messages_[0]->id(), ec.message());
  }
  task->pop();
  task->next_step_ = NextStep::Consume;
  task->submit();
}

void ConsumeTask::onForward(std::shared_ptr<ConsumeTask> task, const std::error_code& ec) {
  assert(task->fifo_);
  assert(!task->messages_.empty());
  if (ec) {
    SPDLOG_DEBUG("Failed to forward Message[message-id={}] to DLQ", task->messages_[0]->id());
    task->next_step_ = NextStep::Forward;
    task->schedule();
  } else {
    SPDLOG_DEBUG("Message[message-id={}] forwarded to DLQ", task->messages_[0]->id());
    task->pop();
    task->next_step_ = NextStep::Consume;
    task->submit();
  }
}

void ConsumeTask::process() {
  auto svc = service_.lock();
  if (!svc) {
    SPDLOG_DEBUG("ConsumeMessageService has destructed");
    return;
  }

  if (messages_.empty()) {
    SPDLOG_DEBUG("No more messages to process");
    return;
  }

  auto self = shared_from_this();

  switch (next_step_) {
    case NextStep::Consume: {
      const auto& listener = svc->listener();
      auto it = messages_.begin();
      SPDLOG_DEBUG("Start to process message[message-id={}]", (*it)->id());
      svc->preHandle(**it);
      auto result = listener(**it);
      svc->postHandle(**it, result);
      switch (result) {
        case ConsumeResult::SUCCESS: {
          auto callback = std::bind(&ConsumeTask::onAck, self, std::placeholders::_1);
          svc->ack(**it, callback);
          break;
        }
        case ConsumeResult::FAILURE: {
          if (fifo_) {
            next_step_ = NextStep::Consume;
            // Increase delivery attempts.
            auto raw = const_cast<Message*>((*it).get());
            raw->mutableExtension().delivery_attempt++;
            schedule();
          } else {
            // For standard way of processing, Nack to server.
            auto callback = std::bind(&ConsumeTask::onNack, self, std::placeholders::_1);
            svc->nack(**it, callback);
          }
          break;
        }
      }
      break;
    }

    case NextStep::Ack: {
      assert(!messages_.empty());
      auto callback = std::bind(&ConsumeTask::onAck, self, std::placeholders::_1);
      svc->ack(*messages_[0], callback);
      break;
    }
    case NextStep::Forward: {
      assert(!messages_.empty());
      auto callback = std::bind(&ConsumeTask::onForward, self, std::placeholders::_1);
      svc->forward(*messages_[0], callback);
      break;
    }
  }
}

ROCKETMQ_NAMESPACE_END