redis分布式锁的实现----C语言_c语言实现分布式锁

EX和NX的区别

ex 设置键的过期时间为 second 秒。NX ：只在键不存在时，才对键进行设置操作。

main.cpp

#include "redis.h"
#include <unistd.h>
int main()
{
	Redis *r = new Redis();
    r->connectRedis("127.0.0.1",6379,5);
    while (r->tryLock(40) != 0)
    {
        /* code */
        sleep(10);
    }
	return 0;
}
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redis.h

#ifndef _REDIS_H_
#define _REDIS_H_

#include <iostream>
#include <string.h>
#include <string>
#include <stdio.h>

#include <hiredis/hiredis.h>

class Redis
{
public:
    Redis();
    ~Redis();
    int connectRedis(std::string addr, int port, int time_out);
    int tryLock(int duration);
    redisReply *ExecuteCmd(const char *cmd, char *data = NULL, int dataSize = 0);
private:
    redisContext *_connect;
    redisReply *_reply;

private:
    int m_timeOutConnect;
    struct timeval m_tv; //redis  命令超时时间
    redisContext *m_redisContent;
    std::string m_redisIp;
    int m_redisPort;
};

#endif //_REDIS_H_
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redis.cpp

#include "redis.h"

Redis::Redis() {}

Redis::~Redis()
{
    this->_connect = NULL;
    this->_reply = NULL;
}

int Redis::connectRedis(std::string addr, int port, int time_out)
{
    m_redisIp = addr;
    m_redisPort = port;

    int ret = -1;
    //struct timeval tv;
    m_tv.tv_sec = time_out;
    m_tv.tv_usec = 0;
    m_timeOutConnect = time_out;

    m_redisContent = redisConnectWithTimeout(m_redisIp.c_str(), m_redisPort, m_tv);
    if (m_redisContent == NULL)
    {
        ret = -1;
        return ret;
    }
    else
    {
        if (m_redisContent->err != 0)
        {
            std::cout << "connect redis ip:" << m_redisIp << ",port:" << m_redisPort << ",error:" << m_redisContent->errstr;
            ret = -1;
            redisFree(m_redisContent);
            m_redisContent = NULL;
            return ret;
        }
    }
    // ret = (int)authRedis();
    redisSetTimeout(m_redisContent, m_tv);
    redisEnableKeepAlive(m_redisContent);
}

int Redis::tryLock(int duration)
{
    int ret = -1;
    char cmdBuf[256] = {0};

    sprintf(cmdBuf, "set %s %s ex %d nx", "gbdlock", "0.0.0.0", duration); //ex 设置键的过期时间为 second 秒。NX ：只在键不存在时，才对键进行设置操作。

    redisReply *reply = ExecuteCmd(cmdBuf);
    if (reply && reply->type != REDIS_REPLY_NIL && strcmp(reply->str, "OK") == 0)
    {
        ret = 0;
        std::cout << "redis set lock OK!!!"
                  << "0.0.0.0" << std::endl;
    }
    else
    {
        char cmdBuf1[256] = {0};

        /* get lock */
        sprintf(cmdBuf1, "GET %s", "gbdlock");
        reply = ExecuteCmd(cmdBuf1);
        if (reply && reply->type != REDIS_REPLY_NIL)
        {
            if (reply->str && !strcmp("gbdlock", reply->str))
            {
                ret = 0;
                std::cout << "Get lock succ: integer = " << reply->integer << " str = " << reply->str;
            }
        }
        std::cout << "redis set lock fail!!!"
                  << "gbdlock" << std::endl;
    }

    if (reply != NULL)
    {
        freeReplyObject(reply);
    }

EXIT:
    return ret;
}

redisReply *Redis::ExecuteCmd(const char *cmd, char *data, int dataSize)
{
    if (m_redisContent == NULL)
    {
        std::cout << "Redis: m_redisContent == NULL error";
        return NULL;
    }

    redisReply *reply = NULL;
    if (data == NULL)
    {
        reply = (redisReply *)redisCommand(m_redisContent, cmd);
    }
    else
    {
        if (dataSize > 2 * 1024 * 1024 /*一个二进制redis数据的最大长度*/)
        {
            std::cout << "redis dataSize more then MAX_REDIS_BIN_LEN ";
            return NULL;
        }
        reply = (redisReply *)redisCommand(m_redisContent, cmd, data, dataSize);
        //redisReply *reply = (redisReply *)redisCommand(m_redisContent, "RPUSH %s %b", listName, data, dataSize);
    }
    return reply;
}
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makefile

redis: main.cpp redis.cpp
	g++ main.cpp redis.cpp -o test -L /usr/local/lib/ -lhiredis
clean:
	rm redis
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