火山引擎消息队列 RocketMQ 5.x版本提供同步发送、异步发送两种方式来发送普通消息。本文介绍如何通过不同方式发送普通消息。发送普通消息前请在控制台创建普通消息类型topic

同步发送是指消息发送方发出一条消息后，会在收到服务端返回响应之后才发下一条消息的通讯方式。一般用于较为重要的消息发送场景。
同步发送方式发送普通消息的示例代码如下

#include <algorithm>
#include <atomic>
#include <iostream>
#include <memory>
#include <random>
#include <string>
#include <system_error>

#include "gflags/gflags.h"
#include "rocketmq/CredentialsProvider.h"
#include "rocketmq/Logger.h"
#include "rocketmq/Message.h"
#include "rocketmq/Producer.h"

using namespace ROCKETMQ_NAMESPACE;

const std::string& alphaNumeric() {
  static std::string alpha_numeric("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
  return alpha_numeric;
}

std::string randomString(std::string::size_type len) {
  std::string result;
  result.reserve(len);
  std::random_device rd;
  std::mt19937 generator(rd());
  std::string source(alphaNumeric());
  std::string::size_type generated = 0;
  while (generated < len) {
    std::shuffle(source.begin(), source.end(), generator);
    std::string::size_type delta = std::min({len - generated, source.length()});
    result.append(source.substr(0, delta));
    generated += delta;
  }
  return result;
}

/*
     * 设置为您从火山引擎消息队列 RocketMQ版控制台获取的接入点信息，类似“http://{INSTANCE_ID}.rocketmq.ivolces.com.com:8080”。
     * 设置RocketMQ实例的AccessKey ID和AccessKey Secret。
    */
DEFINE_string(topic, "xxxx", "Topic to which messages are published");
DEFINE_string(access_point, "rocketmq-xxxx:8080", "Service access URL, provided by your service provider");
DEFINE_int32(message_body_size, 4096, "Message body size");
DEFINE_uint32(total, 256, "Number of sample messages to publish");
DEFINE_string(access_key, "xxxxx", "Your access key ID");
DEFINE_string(access_secret, "xxxx", "Your access secret");
DEFINE_bool(tls, false, "Use HTTP2 with TLS/SSL"); //当前火山不支持tsl/ssl模式,需要填写false

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

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

  // Access Key/Secret pair may be acquired from management console
  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 producers, singleton pattern is recommended.
  auto producer = Producer::newBuilder()
                      .withConfiguration(Configuration::newBuilder()
                                             .withEndpoints(FLAGS_access_point)
                                             .withCredentialsProvider(credentials_provider)
                                             .withSsl(FLAGS_tls)
                                             .build())
                      .withTopics({FLAGS_topic})
                      .build();

  std::atomic_bool stopped;
  std::atomic_long count(0);

  auto stats_lambda = [&] {
    while (!stopped.load(std::memory_order_relaxed)) {
      long cnt = count.load(std::memory_order_relaxed);
      while (!count.compare_exchange_weak(cnt, 0)) {
        cnt = count.load(std::memory_order_relaxed);
      }
      std::this_thread::sleep_for(std::chrono::seconds(1));
      std::cout << "QPS: " << cnt << std::endl;
    }
  };

  std::thread stats_thread(stats_lambda);

  std::string body = randomString(FLAGS_message_body_size);

  try {
    for (std::size_t i = 0; i < FLAGS_total; ++i) {
      auto message = Message::newBuilder()
                         .withTopic(FLAGS_topic)
                         .withTag("TagA")
                         .withKeys({"Key-" + std::to_string(i)})
                         .withBody(body)
                         .build();
      std::error_code ec;
      SendReceipt send_receipt = producer.send(std::move(message), ec);
      if (ec) {
        std::cerr << "Failed to publish message to " << FLAGS_topic << ". Cause: " << ec.message() << std::endl;
      } else {
        std::cout << "Publish message to " << FLAGS_topic << " OK. Message-ID: " << send_receipt.message_id
                  << std::endl;
        count++;
      }
    }
  } catch (...) {
    std::cerr << "Ah...No!!!" << std::endl;
  }
  stopped.store(true, std::memory_order_relaxed);
  if (stats_thread.joinable()) {
    stats_thread.join();
  }

  return EXIT_SUCCESS;
}

异步发送是指发送方发出一条消息后，不等服务端返回响应，接着发送下一条消息的通讯方式。异步发送可以避免线程阻塞，允许程序继续执行其他任务，从而提高系统的吞吐量和性能。
异步发送方式发送普通消息的示例代码如下。

#include <algorithm>
#include <atomic>
#include <condition_variable>
#include <iostream>
#include <mutex>
#include <random>
#include <string>
#include <system_error>

#include "gflags/gflags.h"
#include "rocketmq/Message.h"
#include "rocketmq/Producer.h"

using namespace ROCKETMQ_NAMESPACE;

/**
 * @brief A simple Semaphore to limit request concurrency.
 */
class Semaphore {
public:
  Semaphore(std::size_t permits) : permits_(permits) {
  }

  /**
   * @brief Acquire a permit.
   */
  void acquire() {
    while (true) {
      std::unique_lock<std::mutex> lk(mtx_);
      if (permits_ > 0) {
        permits_--;
        return;
      }
      cv_.wait(lk, [this]() { return permits_ > 0; });
    }
  }

  /**
   * @brief Release the permit back to semaphore.
   */
  void release() {
    std::unique_lock<std::mutex> lk(mtx_);
    permits_++;
    if (1 == permits_) {
      cv_.notify_one();
    }
  }

private:
  std::size_t permits_{0};
  std::mutex mtx_;
  std::condition_variable cv_;
};

const std::string& alphaNumeric() {
  static std::string alpha_numeric("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
  return alpha_numeric;
}

std::string randomString(std::string::size_type len) {
  std::string result;
  result.reserve(len);
  std::random_device rd;
  std::mt19937 generator(rd());
  std::string source(alphaNumeric());
  std::string::size_type generated = 0;
  while (generated < len) {
    std::shuffle(source.begin(), source.end(), generator);
    std::string::size_type delta = std::min({len - generated, source.length()});
    result.append(source.substr(0, delta));
    generated += delta;
  }
  return result;
}

/*
     * 设置为您从火山引擎消息队列 RocketMQ版控制台获取的接入点信息，类似“http://{INSTANCE_ID}.rocketmq.ivolces.com.com:8080”。
     * 设置RocketMQ实例的AccessKey ID和AccessKey Secret。
    */
DEFINE_string(topic, "xxxx", "Topic to which messages are published");
DEFINE_string(access_point, "rocketmq-xxxx:8080", "Service access URL, provided by your service provider");
DEFINE_int32(message_body_size, 4096, "Message body size");
DEFINE_uint32(total, 256, "Number of sample messages to publish");
DEFINE_string(access_key, "xxxxx", "Your access key ID");
DEFINE_string(access_secret, "xxxx", "Your access secret");
DEFINE_bool(tls, false, "Use HTTP2 with TLS/SSL"); //当前火山不支持tsl/ssl模式,需要填写false

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

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

  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 producers, singletion pattern is recommended.
  auto producer = Producer::newBuilder()
                      .withConfiguration(Configuration::newBuilder()
                                             .withEndpoints(FLAGS_access_point)
                                             .withCredentialsProvider(credentials_provider)
                                             .withSsl(FLAGS_tls)
                                             .build())
                      .withTopics({FLAGS_topic})
                      .build();

  std::atomic_bool stopped;
  std::atomic_long count(0);

  auto stats_lambda = [&] {
    while (!stopped.load(std::memory_order_relaxed)) {
      long cnt = count.load(std::memory_order_relaxed);
      while (!count.compare_exchange_weak(cnt, 0)) {
        cnt = count.load(std::memory_order_relaxed);
      }
      std::this_thread::sleep_for(std::chrono::seconds(1));
      std::cout << "QPS: " << cnt << std::endl;
    }
  };

  std::thread stats_thread(stats_lambda);

  std::string body = randomString(FLAGS_message_body_size);

  std::size_t completed = 0;
  std::mutex mtx;
  std::condition_variable cv;

  std::unique_ptr<Semaphore> semaphore(new Semaphore(FLAGS_concurrency));

  auto send_callback = [&](const std::error_code& ec, const SendReceipt& receipt) {
    std::unique_lock<std::mutex> lk(mtx);
    semaphore->release();
    completed++;
    count++;
    if (completed >= FLAGS_total) {
      cv.notify_all();
    }
  };

  for (std::size_t i = 0; i < FLAGS_total; ++i) {
    auto message = Message::newBuilder()
                       .withTopic(FLAGS_topic)
                       .withTag("TagA")
                       .withKeys({"Key-" + std::to_string(i)})
                       .withBody(body)
                       .build();
    semaphore->acquire();
    producer.send(std::move(message), send_callback);
  }

  {
    std::unique_lock<std::mutex> lk(mtx);
    cv.wait(lk, [&]() { return completed >= FLAGS_total; });
    std::cout << "Completed: " << completed << ", total: " << FLAGS_total << std::endl;
  }

  stopped.store(true, std::memory_order_relaxed);
  if (stats_thread.joinable()) {
    stats_thread.join();
  }

  return EXIT_SUCCESS;
}

RocketMQ 5.x 支持两种消费模式，分别为 Push Consumer 和 Simple Consumer。前者为服务端推送消息，后者为主动拉取消息。推荐使用Push Consumer
Push Consumer消费示例代码如下：

#include <chrono>
#include <iostream>
#include <thread>

#include "gflags/gflags.h"
#include "rocketmq/Logger.h"
#include "rocketmq/PushConsumer.h"

using namespace ROCKETMQ_NAMESPACE;

/*
     * 设置为您从火山引擎消息队列 RocketMQ版控制台获取的接入点信息，类似“http://{INSTANCE_ID}.rocketmq.ivolces.com.com:8080”。
     * 设置RocketMQ实例的AccessKey ID和AccessKey Secret。
    */
DEFINE_string(topic, "xxxx", "Topic to which messages are published");
DEFINE_string(group, "xxxx", "GroupId, created through your instance management console");
DEFINE_string(access_point, "rocketmq-xxxx:8080", "Service access URL, provided by your service provider");
DEFINE_int32(message_body_size, 4096, "Message body size");
DEFINE_uint32(total, 256, "Number of sample messages to publish");
DEFINE_string(access_key, "xxxxx", "Your access key ID");
DEFINE_string(access_secret, "xxxx", "Your access secret");
DEFINE_bool(tls, false, "Use HTTP2 with TLS/SSL"); //当前火山不支持tsl/ssl模式,需要填写false

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

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

  std::string tag = "*";

  auto listener = [](const Message& message) {
    std::cout << "Received a message[topic=" << message.topic() << ", MsgId=" << message.id() << "]" << std::endl;
    return ConsumeResult::SUCCESS;
  };

  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, singletion pattern is recommended.
  auto push_consumer = PushConsumer::newBuilder()
                           .withGroup(FLAGS_group)
                           .withConfiguration(Configuration::newBuilder()
                                                  .withEndpoints(FLAGS_access_point)
                                                  .withRequestTimeout(std::chrono::seconds(3))
                                                  .withCredentialsProvider(credentials_provider)
                                                  .withSsl(FLAGS_tls)
                                                  .build())
                           .withConsumeThreads(4)
                           .withListener(listener)
                           .subscribe(FLAGS_topic, tag)
                           .build();

  std::this_thread::sleep_for(std::chrono::minutes(30));

  return EXIT_SUCCESS;
}