数据库应用之--Redis+mysql实现大量数据的读写，以及高并发

一、开发背景

在项目开发过程中中遇到了以下三个需求：

　　1. 多个用户同时上传数据；

　　2. 数据库需要支持同时读写；

　　3. 1分钟内存储上万条数据；

根据对Mysql的测试情况，遇到以下问题：

　　1. 最先遇到压力的是服务器，在写入2500-3000条数据时，服务器崩溃了；

　　2. 当数据库写入时，耗时太长，10000条数据，大概需要505.887s，相当于8分钟，如下：

　　a. 表结构：

　　

　　b. 数据库Procedure:

DROP PROCEDURE IF EXISTS my_insert;
CREATE PROCEDURE my_insert()
BEGIN
   DECLARE n int DEFAULT 1;
        loopname:LOOP
            INSERT INTO car_pathinfo_driver_cpy(id, linkphone,cartype,carcolor,carnumber,drivername,pubtimes)VALUES(n+500,'','雪弗兰','白','豫A190XS','siker','');
            SET n=n+1;
        IF n=10000 THEN
            LEAVE loopname;
        END IF;
        END LOOP loopname;
END;
CALL my_insert();

　　c. 运行结果如下：

　　

　　3. 不断的数据库写入导致数据库压力过大；

出现以上问题，是由于mysql是基于磁盘的IO，基于服务响应性能考虑，就需要给数据做缓存，所以决定使用Mysql+redis缓存的解决方案，将业务热数据写入Redis缓存，使得高频业务数据可以直接从内存读取，提高系统整体响应速度。

二、使用Redis+Mysql需要考虑的问题
　　使用redis缓存+mysql数据库存储能解决：

　　1. 数据读写的速度

　　2. 服务器的压力问题

　　同时，就需要考虑同步问题了，Redis和Mysql的同步问题

三、Redis+mysql同步解决方案

　　1.写Redis->redis写mysql,读Mysql。

　　以下是一个Redis+mysql同步的示例，该示例测试了写入100000条数据的效率，先向Redis写入100000条数据，再将数据读出，写入Mysql。

　　　　批量写入缓解了服务器的压力。

stdafx.h

// stdafx.h : 标准系统包含文件的包含文件，
// 或是经常使用但不常更改的
// 特定于项目的包含文件
//

#pragma once

#include "targetver.h"

#include <stdio.h>
#include <tchar.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <assert.h>
#include <vector>
#include "hiredis.h"
#include <Windows.h>
#include "mysql.h"

#ifdef _DEBUG
#pragma comment(lib, "hiredis_d.lib")
#pragma comment(lib, "Win32_Interop_d.lib")
#else
#pragma comment(lib, "hiredis.lib")
#pragma comment(lib, "Win32_Interop.lib")

#endif
#pragma comment(lib, "AdvAPI32.Lib")
#pragma comment(lib, "DbgHelp.Lib")
#pragma comment (lib, "Shlwapi.lib")
#pragma comment(lib,"libmysql.lib")

using namespace std;

typedef struct testData
{
    int iHeight;
    int iWidth;
    char szValue[];
    char szHValue[];
}stTestData, *pstTestData;

test.h

#include "stdafx.h"
#include "DBHandle.h"

int main()
{

    DBHandle *dbHandle = new DBHandle();
    thread tWriteDataToRedis(&DBHandle::writeHsetToRedis, *dbHandle);
    tWriteDataToRedis.join();

    return ;
}

DBHandle.h

#pragma once
#include <mutex>
#include <thread>

class DBHandle
{
public:
    DBHandle();
    ~DBHandle();

    bool connectRedis(string strIp, int iPort, string strPwd);
    void freeRedis();

    int getRedisDBSize();

    bool writeHsetToRedis();
    bool readDataFromRedis();

    bool connectMysql();
    void FreeMysqlConnect();

    bool insertDataToMysql(string strData);

    redisContext* m_pRedisContext;
    MYSQL m_mysql;
    MYSQL_RES *res;     //行的一个查询结果集

};

DBHandle.cpp

#include "stdafx.h"
#include "DBHandle.h"

DBHandle::DBHandle()
{
    m_pRedisContext = NULL;
}

DBHandle::~DBHandle()
{
    if (m_pRedisContext != NULL)
    {
        m_pRedisContext = NULL;
    }
}

bool DBHandle::connectRedis(string strIp, int iPort, string strPwd)
{
    //redis默认监听端口为6387 可以再配置文件中修改
    char szBuf[] = {};
    strcpy_s(szBuf, sizeof(strIp), strIp.c_str());
    m_pRedisContext = redisConnect(szBuf, iPort);
    if (NULL == m_pRedisContext || m_pRedisContext->err)
    {
        return false;
    }

    //输入Redis密码
    strcpy_s(szBuf, sizeof(strPwd), strPwd.c_str());
    redisReply *pRedisReply = (redisReply*)redisCommand(m_pRedisContext, "AUTH %s", szBuf);
    if (NULL != pRedisReply)
    {
        freeReplyObject(pRedisReply);
    }
    if (NULL == pRedisReply->str)
    {
        return false;
    }
    return true;

}

void DBHandle::freeRedis()
{
    redisFree(m_pRedisContext);
    if (m_pRedisContext != NULL)
    {
        m_pRedisContext = NULL;
    }
}

int DBHandle::getRedisDBSize()
{
    //查看list长度
    int iListLen = ;
    //redisReply *pRedisReply = (redisReply *)redisCommand(m_pRedisContext, "LLen datalist");
    redisReply *pRedisReply = (redisReply *)redisCommand(m_pRedisContext, "DBSIZE");
    if (NULL != pRedisReply)
    {
        if (NULL == pRedisReply->integer)
        {
            return false;
        }
        iListLen = pRedisReply->integer;
        freeReplyObject(pRedisReply);
    }
    if (NULL == pRedisReply)
    {
        printf("%s \r\n", m_pRedisContext->errstr);
        return false;
    }

    return iListLen;
}

bool DBHandle::writeHsetToRedis()
{
    bool bFlag = connectRedis("127.0.0.1", , "");
    if (false == bFlag)
    {
        return false;
    }

    time_t st = time(NULL);//秒
    stTestData data = {};
    int i = ;
    while (i<)
    {

        data.iHeight = i;
        data.iWidth = ;
        char szBuf[] = {};
        sprintf_s(szBuf, "width%d", i);
        strcpy_s(data.szValue, , szBuf);
        sprintf_s(data.szHValue, "%s%d", "heighttest", i);

        //向Redis写入数据hset location (interger)1 "width"
        sprintf_s(szBuf, "hset location%d value %s", i, data.szValue);
        redisReply *pRedisReply = (redisReply *)redisCommand(m_pRedisContext, szBuf);
        if (NULL != pRedisReply)
        {
            freeReplyObject(pRedisReply);
        }
        i++;
    }

    printf("write finish");
    readDataFromRedis();

    time_t et = time(NULL);
    int iUsed = st - et;
    printf("used time is %d", iUsed);
    freeRedis();
    return true;

}

bool DBHandle::readDataFromRedis()
{
    /*bool bFlag = connectRedis("127.0.0.1", 6379, "123456");
    if (false == bFlag)
    {
        return false;
    }*/

    printf("read start");

    int iSize = getListSize();
    if (iSize <= )
    {
        return false;
    }
    bool bSuc = connectMysql();
    if (bSuc == false)
    {
        return false;
    }

    int iCount = iSize;//计数
    while (iCount > )
    {
        //用get命令获取数据
        redisReply *pRedisReply = (redisReply*)redisCommand(m_pRedisContext, "RPOP datalist");
        if (NULL == pRedisReply)
        {
            return false;
        }
        if (NULL != pRedisReply->str)
        {
            string str = pRedisReply->str;
            insertDataToMysql(str);
            freeReplyObject(pRedisReply);
        }
        iCount--;
    }

    printf("read finish");

    return true;

}

bool DBHandle::connectMysql()
{
    mysql_init(&m_mysql);

    // Connects to a MySQL server
    const char host[] = "192.168.4.8";
    const char user[] = "root";
    const char passwd[] = "";
    const char db[] = "topproductline";
    unsigned int port = ;
    const char *unix_socket = NULL;
    unsigned long client_flag = ;

    /*A MYSQL* connection handler if the connection was successful,
    NULL if the connection was unsuccessful. For a successful connection,
    the return value is the same as the value of the first parameter.*/
    if (mysql_real_connect(&m_mysql, host, user, passwd, db, port, unix_socket, client_flag)) {
        printf("The connection was successful.\n");
        return true;
    }
    else {
        printf("Error connecting to database:%s\n", mysql_error(&m_mysql));
        return false;
    }
}

void DBHandle::FreeMysqlConnect()
{
    mysql_free_result(res);
    mysql_close(&m_mysql);
}

bool DBHandle::insertDataToMysql(string strData)
{
    char szQuery[] = {};
    sprintf_s(szQuery, "insert into a_test (type) values ('%s');", strData.c_str());
    if (mysql_query(&m_mysql, szQuery)) {
        printf("Query failed (%s)\n", mysql_error(&m_mysql));
        return false;
    }
    else {
        printf("Insert success\n");
        return true;
    }
}

　　测试结果：

　　2.写redis->写mysql,读Redis->未找到->读Mysql