关于librdkafka库的介绍,可以参考kafka的c/c++高性能客户端librdkafka简介,本文使用librdkafka库来进行kafka的简单的消费
librdkafka在c语言的基础上封装了一层c++的API,可以实现kafka的消费操作,基本操作步骤如下
1、创建kafka 配置
RdKafka::Conf *conf = nullptr;
conf = RdKafka::Conf::create(RdKafka::Conf::CONF_GLOBAL);
2、设置kafka各项参数
/*设置broker list*/
conf->set("bootstrap.servers", brokers_, errstr);
/*设置consumer group*/
conf->set("group.id", groupid_, errstr);
/*每次从单个分区中拉取消息的最大尺寸*/
conf->set("max.partition.fetch.bytes", strfetch_num, errstr);
3、创建kafka topic配置
RdKafka::Conf *tconf = nullptr;
tconf = RdKafka::Conf::create(RdKafka::Conf::CONF_TOPIC);
4、设置kafka topic参数
if(tconf->set("auto.offset.reset", "smallest", errstr)
5、创建kafka consumer实例
kafka_consumer_ = RdKafka::Consumer::create(conf, errstr);
6、创建kafka topic
RdKafka::Topic::create(kafka_consumer_, topics_, tconf, errstr);
7、启动kafka consumer实例
RdKafka::ErrorCode resp = kafka_consumer_->start(topic_, partition_, offset_);
8、消费kafka
kafka_consumer_->consume(topic_, partition_, timeout_ms);
9、阻塞等待消息
kafka_consumer_->poll(0);
10、停止消费
kafka_consumer_->stop(topic_, partition_);
11、销毁consumer实例
RdKafka::wait_destroyed(5000);
完整代码
my_consumer.h:
#include
#include
#include
#include
#include
#include
#include "../src-cpp/rdkafkacpp.h" class kafka_consumer_client{ public: kafka_consumer_client(const std::string& brokers, const std::string& topics, std::string groupid, int64_t offset); //kafka_consumer_client(); virtual ~kafka_consumer_client(); bool initClient(); bool consume(int timeout_ms); void finalize(); private: void consumer(RdKafka::Message *msg, void *opt); std::string brokers_; std::string topics_; std::string groupid_; int64_t last_offset_ = 0; RdKafka::Consumer *kafka_consumer_ = nullptr; RdKafka::Topic *topic_ = nullptr; int64_t offset_ = RdKafka::Topic::OFFSET_BEGINNING; int32_t partition_ = 0; };
my_consumer.cpp
#include "my_consumer_cpp.h"
bool run_ = true;
static void sigterm (int sig) {
run_ = false;
}
kafka_consumer_client::kafka_consumer_client(const std::string& brokers, const std::string& topics, std::string groupid, int64_t offset)
:brokers_(brokers),
topics_(topics),
groupid_(groupid),
offset_(offset){
}
//kafka_consumer_client::kafka_consumer_client(){}
kafka_consumer_client::~kafka_consumer_client(){}
bool kafka_consumer_client::initClient(){
RdKafka::Conf *conf = nullptr;
conf = RdKafka::Conf::create(RdKafka::Conf::CONF_GLOBAL);
if(!conf){
fprintf(stderr, "RdKafka create global conf failed\n");
return false;
}
std::string errstr;
/*设置broker list*/
if (conf->set("bootstrap.servers", brokers_, errstr) != RdKafka::Conf::CONF_OK){
fprintf(stderr, "RdKafka conf set brokerlist failed : %s\n", errstr.c_str());
}
/*设置consumer group*/
if (conf->set("group.id", groupid_, errstr) != RdKafka::Conf::CONF_OK){
fprintf(stderr, "RdKafka conf set group.id failed : %s\n", errstr.c_str());
}
std::string strfetch_num = "10240000";