cpp/examples/ExampleSimpleConsumer.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 <chrono>
#include <iostream>

#include "gflags/gflags.h"
#include "rocketmq/ErrorCode.h"
#include "rocketmq/Logger.h"
#include "rocketmq/SimpleConsumer.h"
#include "spdlog/spdlog.h"

using namespace ROCKETMQ_NAMESPACE;

DEFINE_string(topic, "NormalTopic", "Topic to which messages are published");
DEFINE_string(access_point, "127.0.0.1:8081", "Service access URL, provided by your service provider");
DEFINE_string(group, "SimpleConsumer", "GroupId, created through your instance management console");
DEFINE_string(access_key, "", "Your access key ID");
DEFINE_string(access_secret, "", "Your access secret");
DEFINE_bool(tls, false, "Use HTTP2 with TLS/SSL");

int main(int argc, char* argv[]) {
  gflags::ParseCommandLineFlags(&argc, &argv, true);

  auto& logger = getLogger();
  logger.setConsoleLevel(Level::Info);
  logger.setLevel(Level::Info);
  logger.init();

  // Subscribe with Tag or SQL92 to filter messages on the server side
  std::string tag = "*";
  // auto filter_expression = new FilterExpression("a = 1", ExpressionType::SQL92);

  CredentialsProviderPtr credentials_provider;
  if (!FLAGS_access_key.empty() && !FLAGS_access_secret.empty()) {
    credentials_provider = std::make_shared<StaticCredentialsProvider>(
        FLAGS_access_key, FLAGS_access_secret);
  }

  // In most case, you don't need to create too many consumers, singleton pattern is recommended.
  auto simple_consumer = SimpleConsumer::newBuilder()
                             .withGroup(FLAGS_group)
                             .withConfiguration(Configuration::newBuilder()
                                                    .withEndpoints(FLAGS_access_point)
                                                    .withCredentialsProvider(credentials_provider)
                                                    .withSsl(FLAGS_tls)
                                                    .build())
                             .subscribe(FLAGS_topic, tag)
                             // .subscribe(FLAGS_topic, *filter_expression)
                             .withAwaitDuration(std::chrono::seconds(10))
                             .build();
  std::size_t total = 0;

  // Should use while (true) instead
  for (int j = 0; j < 30; j++) {
    std::vector<MessageConstSharedPtr> messages;
    std::error_code ec;
    simple_consumer.receive(4, std::chrono::seconds(15), ec, messages);

    if (ec) {
      std::cerr << "Failed to receive messages. Cause: " << ec.message() << std::endl;
    } else {
      std::cout << "Received " << messages.size() << " messages" << std::endl;
    }

    for (const auto& message : messages) {
      std::string receipt_handle = message->extension().receipt_handle;
      SPDLOG_INFO("Receive message, topic={}, message-id={}, receipt-handle={}]", message->topic(), message->id(), receipt_handle);

      if (total++ % 2 == 0) {
        // Consume message successfully then ack it
        simple_consumer.ack(*message, ec);
        if (ec) {
          SPDLOG_ERROR("Failed to ack message. Cause: {}", ec.message());
        } else {
          SPDLOG_INFO("Ack message, topic={}, message-id={}, receipt-handle={}]", message->topic(), message->id(), receipt_handle);
        }
      } else {
        // Extend the message consumption time by modifying the invisible duration API
        for (int k = 0; k < 3; k++) {
          simple_consumer.changeInvisibleDuration(
              *message, receipt_handle, std::chrono::seconds(15), ec);
          if (ec) {
            SPDLOG_WARN("Failed to change invisible duration of message. Cause: ", ec.message());
          } else {
            SPDLOG_INFO("Change invisible duration, topic={}, message-id={}, times={}, receipt-handle={}]",
                        message->topic(), message->id(), k, receipt_handle);
          }
        }
      }
    }
  }

  return EXIT_SUCCESS;
}