Centos 7下使用C++使用Rdkafka库实现生产者消费者

1. 了解 Kafka

Apache Kafka 是一个分布式流处理平台，核心功能包括：

• 发布/订阅消息系统：解耦生产者和消费者

• 分布式存储：持久化、容错的消息存储

• 流处理：实时处理数据流

核心概念：

2. 了解 rdkafka

rdkafka 是 Kafka 的 C/C++ 客户端库，提供：

• 高性能生产/消费 API（支持 C/C++/Python 等）

• 特性：

  • 异步/同步发送模式

  • 自动负载均衡

  • 消息压缩（gzip, snappy, lz4）

  • SASL 认证

  • 精确一次语义（EOS）

• 开源地址：edenhill/librdkafka

3. 代码实现

以下是使用 librdkafka 的 C++ 接口操作 Kafka 的生产者和消费者完整实现：

生产者代码 (producer.cpp)

#include <iostream>
#include <string>
#include <sstream>
#include <librdkafka/rdkafkacpp.h>

class ProducerDeliveryReportCb : public RdKafka::DeliveryReportCb {
public:
    void dr_cb(RdKafka::Message &message) {
        if (message.err()) {
            std::cerr << "消息发送失败: " << message.errstr() << std::endl;
        } else {
            std::cout << "消息发送成功: " << message.topic_name() 
                      << " [" << message.partition() << "] @ " 
                      << message.offset() << std::endl;
        }
    }
};

int main() {
    // 1. 创建配置对象
    RdKafka::Conf *conf = RdKafka::Conf::create(RdKafka::Conf::CONF_GLOBAL);
    std::string errstr;

    // 2. 设置配置参数
    if (conf->set("bootstrap.servers", "localhost:9092", errstr) != RdKafka::Conf::CONF_OK) {
        std::cerr << "配置错误: " << errstr << std::endl;
        return 1;
    }
    
    // 设置消息确认模式 (all = 最高可靠性)
    if (conf->set("acks", "all", errstr) != RdKafka::Conf::CONF_OK) {
        std::cerr << "配置错误: " << errstr << std::endl;
        return 1;
    }

    // 3. 创建生产者实例
    ProducerDeliveryReportCb delivery_cb;
    if (conf->set("dr_cb", &delivery_cb, errstr) != RdKafka::Conf::CONF_OK) {
        std::cerr << "配置回调错误: " << errstr << std::endl;
        return 1;
    }

    RdKafka::Producer *producer = RdKafka::Producer::create(conf, errstr);
    if (!producer) {
        std::cerr << "创建生产者失败: " << errstr << std::endl;
        return 1;
    }
    delete conf;

    // 4. 创建Topic对象
    RdKafka::Conf *tconf = RdKafka::Conf::create(RdKafka::Conf::CONF_TOPIC);
    RdKafka::Topic *topic = RdKafka::Topic::create(producer,"cpp_test_topic",tconf,errstr);
    if (!topic) {
        std::cerr << "创建Topic失败: " << errstr << std::endl;
        delete tconf;
        return 1;
    }
    delete tconf;

    // 5. 生产消息
    for (int i = 0; i < 10; ++i) {
        std::string key = "key-" + std::to_string(i);
        std::string payload = "Message #" + std::to_string(i);
        
        // 发送消息
        RdKafka::ErrorCode resp = producer->produce(
            topic, 
            RdKafka::Topic::PARTITION_UA, // 自动分区分配
            RdKafka::Producer::RK_MSG_COPY,
            const_cast<char*>(payload.c_str()), payload.size(),
            const_cast<char*>(key.c_str()), key.size(),
            NULL
        );

        if (resp != RdKafka::ERR_NO_ERROR) {
            std::cerr << "生产消息失败: " << RdKafka::err2str(resp) << std::endl;
        } else {
            std::cout << "已发送: " << payload << std::endl;
        }
        
        // 处理事件队列
        producer->poll(0);
    }

    // 6. 等待所有消息完成发送
    while (producer->outq_len() > 0) {
        std::cout << "等待发送队列: " << producer->outq_len() << std::endl;
        producer->poll(100);
    }

    // 7. 清理资源
    delete topic;
    delete producer;

    return 0;
}

消费者代码 (consumer.cpp)

#include <iostream>
#include <string>
#include <csignal>
#include <vector>
#include <librdkafka/rdkafkacpp.h>

bool running = true;

void stop(int sig) {
    running = false;
}

class ConsumerEventCb : public RdKafka::EventCb {
public:
    void event_cb(RdKafka::Event &event) {
        switch (event.type()) {
            case RdKafka::Event::EVENT_ERROR:
                std::cerr << "错误: " << RdKafka::err2str(event.err()) << std::endl;
                break;
            case RdKafka::Event::EVENT_LOG:
                std::cout << "日志: " << event.str() << std::endl;
                break;
            default:
                std::cout << "事件: " << event.type() << ": " << event.str() << std::endl;
                break;
        }
    }
};

int main() {
    // 注册信号处理
    signal(SIGINT, stop);
    signal(SIGTERM, stop);

    // 1. 创建配置对象
    RdKafka::Conf *conf = RdKafka::Conf::create(RdKafka::Conf::CONF_GLOBAL);
    std::string errstr;

    // 2. 设置配置参数
    if (conf->set("bootstrap.servers", "localhost:9092", errstr) != RdKafka::Conf::CONF_OK) {
        std::cerr << "配置错误: " << errstr << std::endl;
        return 1;
    }

    // 设置消费组
    if (conf->set("group.id", "cpp_consumer_group", errstr) != RdKafka::Conf::CONF_OK) {
        std::cerr << "配置错误: " << errstr << std::endl;
        return 1;
    }

    // 从最早的消息开始消费
    if (conf->set("auto.offset.reset", "earliest", errstr) != RdKafka::Conf::CONF_OK) {
        std::cerr << "配置错误: " << errstr << std::endl;
        return 1;
    }

    // 3. 设置事件回调
    ConsumerEventCb event_cb;
    if (conf->set("event_cb", &event_cb, errstr) != RdKafka::Conf::CONF_OK) {
        std::cerr << "设置回调失败: " << errstr << std::endl;
        return 1;
    }

    // 4. 创建消费者实例
    RdKafka::KafkaConsumer *consumer = RdKafka::KafkaConsumer::create(conf, errstr);
    if (!consumer) {
        std::cerr << "创建消费者失败: " << errstr << std::endl;
        return 1;
    }
    delete conf;

    // 5. 订阅Topic
    std::vector<std::string> topics;
    topics.push_back("cpp_test_topic");
    RdKafka::ErrorCode resp = consumer->subscribe(topics);
    if (resp != RdKafka::ERR_NO_ERROR) {
        std::cerr << "订阅失败: " << RdKafka::err2str(resp) << std::endl;
        return 1;
    }

    // 6. 消费消息
    while (running) {
        // 等待消息 (1000ms超时)
        RdKafka::Message *msg = consumer->consume(1000);
        
        switch (msg->err()) {
            case RdKafka::ERR__TIMED_OUT:
                break;  // 超时继续
                
            case RdKafka::ERR_NO_ERROR:
                // 成功消费到消息
                std::cout << "收到消息: "
                          << "主题: " << msg->topic_name() 
                          << " | 分区: [" << msg->partition() << "]"
                          << " | 偏移量: " << msg->offset() << std::endl;
                          
                if (msg->key()) {
                    std::cout << "键: " << *msg->key() << " => ";
                }
                
                std::cout << "值: " << static_cast<const char*>(msg->payload()) 
                          << std::endl;
                break;
                
            default:
                std::cerr << "消费错误: " << msg->errstr() << std::endl;
                break;
        }
        
        // 手动提交偏移量
        consumer->commitAsync(msg);
        delete msg;
    }

    // 7. 关闭消费者
    consumer->close();
    delete consumer;

    return 0;
}

编译运行

# 编译生产者
g++ -o producer producer.cpp -lrdkafka++ -lrdkafka -lpthread -lz -ldl

# 编译消费者
g++ -o consumer consumer.cpp -lrdkafka++ -lrdkafka -lpthread -lz -ldl