mysql异步调用的实现

1.实现原理

现在我们的项目已经实现了异步类XThread，数据库类XMylsq,验证了std::function和std::bind实现回调的功能，现在我们只需要把他们组在一起就行。

2.代码实现 ①这里先把我的代码分享一下

链接：https://pan.baidu.com/s/16fDkpC_g3QVgHTocxygDSQ 
提取码：su1a 

②再次封装XMysql

        新增异步回调结果XMysqlAsynRes,新增回调 *** 作信息XMysqlAsynData,实现异步 *** 作虚函数virtual bool exec(),新增异步 *** 作函数 bool exeAsynSql(const char* sql, std::function fun)，新增异步处理队列std::queue m_sqlQueue。

        主要原理是，主进程加载一个异步数据库，执行流程和主进程分离开。mysql流程在exec()函数中阻塞，不断地去遍历队列的数据， *** 作完之后就进入等待状态。主进程可以通过调用exeAsynSql（）接口将 *** 作放入队列中，等待 *** 作结果。

        XMysql.h和XMysql.cpp

/**********************************************************
 * Author        : 谢名聪
 * Email         : 869408604@qq.com
 * Last modified : 2022-04-21 11:45
 * Filename      : XMysql.h
 * Description   : xsqly类，提供同步异步两种 *** 作
 * *******************************************************/

#ifndef X_MYSQL
#define X_MYSQL

#include "../XThread/XThread.h"
#include "mysqlToProtobuf.h"
#include "../include/mysql/mysql.h"
#include 
#include 
#include 
#include 

struct XMysqlRes
{
    bool suc = false;
    std::vector> res;
};

struct XMysqlAsynRes
{
    XMysqlAsynRes() = default;
    ~XMysqlAsynRes() {
        //释放掉mysql的数据
        if (mysqlRes) {
            mysql_free_result(mysqlRes);
        }
    }
    XMysqlRes xMysqlRes;
    MYSQL_RES* mysqlRes;
    template
    bool getProtoRes(std::vector>& res) {
        //重置遍历的行数
        mysql_data_seek(mysqlRes, 0);
        mysqlToProtobuf(mysqlRes, res);
    }
};


struct XMysqlAsynData
{
    std::function fun;
    const char* sql;
};

class XMysql : public XThread
{
    public:
        virtual bool exec() override;
    public:
        //初始化数据库
        bool init(const char* host, const char* port, const char* user, const char* pwd, const char* db, const uint32_t timeout = 2);
    //---------------------------------------------------------
    //同步 *** 作
    //--------------------------------------------------------
    public:
        //有返回的 *** 作
        XMysqlRes exeSqlStore(const char* sql);
        //无返回的 *** 作
        bool exeSql(const char* sql);
        //定义一个模板，针对不同的protobuf结构
        template
        //这里必须再类内实现，在类外实现的话，进行外部链接的时候会出错
        bool exeSqlProtobuf(const char* sql, std::vector>& protoRes)
        {
            if (!exeSql(sql)) {
                std::cout << "XMysql exeSqlStore error! sql=" << sql << std::endl;
                return false;
            }
            //转成protobuf形式
            mysqlToProtobuf(mysql_store_result(&m_mysql), protoRes);
            return true;
        }
        //校验连接状态
        void check();
        //连接数据库
        bool connect();
    //---------------------------------------------
    //异步操作
    //---------------------------------------------
    public:
        bool exeAsynSql(const char* sql, std::function fun);
    private:
        MYSQL m_mysql;
        std::string m_host = "";
        std::string m_user = "";
        std::string m_pwd = "";
        std::string m_db = "";
        uint32_t m_port = 0;
        uint32_t m_timeout = 0;
    //异步处理
    private:
        std::queue m_sqlQueue;//需要处理的队列
};

#endif

#include "XMysql.h"

bool XMysql::init(const char* host, const char* port, const char* user, const char* pwd, const char* db, const uint32_t timeout)
{
    m_host = host;
    m_port = std::atoi(port);
    m_user = user;
    m_pwd = pwd;
    m_db = db;
    m_timeout = timeout;

    if (connect()) {
        std::cout << "XMysql connect error" << std::endl;
        return false;
    }

    return true;
}

bool XMysql::exeSql(const char* sql)
{
    if (mysql_real_query(&m_mysql,sql,strlen(sql)) != 0) {
        std::cout << "XMysql exeSql error! sql=" << sql << std::endl;
        return false;
    }
   return true;
}

XMysqlRes XMysql::exeSqlStore(const char* sql)
{
    XMysqlRes res;
    check();
    if (!exeSql(sql)) {
        std::cout << "XMysql exeSqlStore error! sql=" << sql << std::endl;
        return res;
    }
    //执行成功
    res.suc = true;
    //查询结果
    auto result = mysql_store_result(&m_mysql);
    //行数
    auto rowNum = mysql_num_rows(result);
    //列数
    auto fiedNum = mysql_num_fields(result);
    for (int i = 0; i < rowNum; i++) {
        auto row = mysql_fetch_row(result);
        std::vector rows;
        for (int j = 0; j < fiedNum; j++) {
            rows.push_back(row[j]);
        }
        res.res.push_back(rows);
    }

    return res;
}

void XMysql::check()
{
    //ping返回0时表示正常
    if (mysql_ping(&m_mysql) != 0) {
        std::cout << "XMysql ping == 0" << std::endl;
        //关闭mysql
        mysql_close(&m_mysql);
        return;
    }
    
    //重新连接
    connect();
}

bool XMysql::connect()
{
    //初始化
    if (!mysql_init(&m_mysql)) {
        std::cout << "XMysql init error!" << std::endl;
        return false;
    }
    //连接数据库
    if (!mysql_real_connect(&m_mysql, m_host.c_str(), m_user.c_str(), m_pwd.c_str(), m_db.c_str(), m_port, NULL, CLIENT_MULTI_STATEMENTS)) {
        std::cout << "XMysql connect error!" << std::endl;
        return false;
    }
    //设置参数
    mysql_options(&m_mysql, MYSQL_OPT_READ_TIMEOUT, &m_timeout);
    mysql_options(&m_mysql, MYSQL_SET_CHARSET_NAME, "utf8");
}

bool XMysql::exeAsynSql(const char* sql, std::function fun)
{
    auto info = new XMysqlAsynData;
    info->sql = sql;
    info->fun = fun;
    m_sqlQueue.push(info);
}

bool XMysql::exec()
{
    XMysqlAsynData* info = nullptr;
    while (status()) {
        if (m_sqlQueue.size() > 0) {
            info = m_sqlQueue.front();
            m_sqlQueue.pop();
            XMysqlRes res;
            check();
            if (!exeSql(info->sql)) {
                std::cout << "XMysql exeAsynSql error! sql=" << info->sql << std::endl;
                continue;
            }
            //执行成功
            res.suc = true;
            //查询结果
            auto result = mysql_store_result(&m_mysql);
            //行数
            auto rowNum = mysql_num_rows(result);
            //列数
            auto fiedNum = mysql_num_fields(result);
            for (int i = 0; i < rowNum; i++) {
                auto row = mysql_fetch_row(result);
                std::vector rows;
                for (int j = 0; j < fiedNum; j++) {
                    rows.push_back(row[j]);
                }
                res.res.push_back(rows); 
            }
            XMysqlAsynRes* asynRes = new XMysqlAsynRes();
            asynRes->xMysqlRes = res;
            asynRes->mysqlRes = result;
            mysql_free_result(result);
            if (info->fun) {
                info->fun(asynRes);
            } else {
                std::cout << "info->fun = nullptr" << std::endl; 
            }
        }
    }

    return true;
}

③在进程基类加入异步数据库

        异步数据库实现后，将他加入主进程类Process中，加入异步mysql类成员m_asynXMysqls，并实现初始化和调用接口，增加异步工具管理容器m_asynTools，在结束程序的时候，可以调用这个工具，结束掉分离出去的异步工具。

Process.h和Process.cpp

/**********************************************************
 * Author        : 谢名聪
 * Email         : 869408604@qq.com
 * Last modified : 2022-04-21 11:42
 * Filename      : Process.h
 * Description   : 进程的基类
 * *******************************************************/

#ifndef PROCESS_H
#define PROCESS_H

#include "XInclude/XMysql/XMysql.h"
#include "XInclude/XConfig/XConfig.h"

class Process
{
    public:
        Process();
        virtual ~Process();

    //进程子类需要实现的逻辑
    private:
        virtual bool initProcess() = 0;
        virtual bool startProcess() = 0;
        virtual bool stopProcess() = 0;

    //main.cpp中调用的逻辑
    public:
        bool init(const std::string config);
        bool start();
        bool stop();
        bool startAsynTools();
        bool stopAsynTools();
    //*********************************************************
    //工具类:包括config socket  redis mysql timer log等
    //*********************************************************

    //---------------------------------------------------------
    //config
    //--------------------------------------------------------
    private:
        std::shared_ptr m_config;
    public:
        //获取配置
        std::string getConfigValue(const std::string groupKey, const std::string key);

    //-----------------------------------------------------------
    //同步数据库，只 *** 作一些简单的逻辑
    //-----------------------------------------------------------
    private:
        std::map> m_XMysqls;
    public:
        //增加数据库服务
        bool addMysqlServer(uint32_t id, const char* host, \
                const char* port, const char* user, \
                const char* pwd, const char* db, \
                uint32_t timeout = 2);
        //无返回值
        bool exeSql(uint32_t id, const char* sql); 
        //返回XMysql
        XMysqlRes exeSqlStore(uint32_t id, const char* sql);
        //返回protobuf
        template
        bool exeSqlProtobuf(uint32_t id, const char* sql, std::vector>& protoRes)
        {
            auto it = m_XMysqls.find(id);
            if (it == m_XMysqls.end()) {
                return false;
            }

            return m_XMysqls[id]->exeSqlProtobuf(sql, protoRes);
        } 
    //------------------------------------------------------------
    //异步mysql 异步类型  有一些不需要马上得到结果的 *** 作可以在这完成
    //-----------------------------------------------------------
    private:
        std::map> m_asynXMysqls;
    public:
        //增加一个异步mysql服务
        bool addAsynMysqlServer(uint32_t id, const char* host, \
                const char* port, const char* user, \
                const char* pwd, const char* db, \
                uint32_t timeout = 20);
        //加入一个异步 *** 作
        bool exeAsynSql(uint32_t id, const char* sql,  std::function func = nullptr);

    public:
        std::string m_name = "";
        uint32_t m_type = 0;
        uint32_t m_id = 0;
        std::vector> m_asynTools;
};
extern Process* g_process;

#endif

#include "Process.h"

Process* g_process = nullptr;

Process::Process()
{
    if (!g_process) {
        g_process = this; 
    }
    if (!m_config) {
        m_config = std::make_shared();
    }
}

Process::~Process()
{
}

bool Process::init(const std::string config)
{
    try {
        // 加载配置
        if (!m_config->load(config)) {
            std::cout << "load config error" << std::endl;
            return false;
        }
        // 初始化进程
        if (!initProcess()) {
            std::cout << "initProcess error!" << std::endl;;
            return false;
        }
        //开启异步工具
        startAsynTools();

    } catch (std::exception& ex) {
        std::cout << "Process, init ex= " << ex.what() << std::endl;
    }

    std::cout << "Process, init success!" << std::endl;
    return true;
}

bool Process::start()
{
    try {
    // 开启服务逻辑
    if (!startProcess()) {
        std::cout << "startProcess error!" << std::endl;
        return false;
    }
    
    } catch (std::exception& ex) {
        std::cout << "PROCESS, start ex = " << ex.what() << std::endl;
    }

    std::cout << "PROCESS, start success!" << std::endl;

    return true;
}

bool Process::stop()
{
    try {
        //关闭工具
        stopAsynTools();
        //关闭服务逻辑
        stopProcess();

        std::cout << "PROCESS, " << m_name << "stopped" << std::endl;;

    } catch (std::exception& ex) {
        std::cout << "stop ex, " << ex.what() << std::endl;
    }

    return true;
}

std::string Process::getConfigValue(const std::string groupKey, const std::string key)
{
    return m_config->getConfigValue(groupKey, key);
}

bool Process::addMysqlServer(uint32_t id, const char* host, \
        const char* port, const char* user, \
        const char* pwd, const char* db, \
        uint32_t timeout)
{
    auto it = m_XMysqls.find(id);
    if (it != m_XMysqls.end()) {
        return true;
    }
    auto mysql = std::make_shared ();
    m_XMysqls[id] = mysql;
    return mysql->init(host, port, user, pwd, db, timeout);
}

bool Process::exeSql(uint32_t id, const char* sql)
{
    auto it = m_XMysqls.find(id);
    if (it == m_XMysqls.end()) {
        return false;
    }

    return m_XMysqls[id]->exeSql(sql);
}


XMysqlRes Process::exeSqlStore(uint32_t id, const char* sql)
{
    auto it = m_XMysqls.find(id);
    if (it == m_XMysqls.end()) {
        return XMysqlRes();
    }

    return m_XMysqls[id]->exeSqlStore(sql);
}

bool Process::addAsynMysqlServer(uint32_t id, const char* host, \
        const char* port, const char* user, \
        const char* pwd, const char* db, \
        uint32_t timeout)
{
    auto it = m_asynXMysqls.find(id);
    if (it != m_asynXMysqls.end()) {
        return true;
    }
    auto mysql = std::make_shared ();
    if (!mysql->init(host, port, user, pwd, db, timeout)) {
        std::cout << "init asynSql error" << std::endl;
        return false;
    }
    std::cout << "addAsynMysqlServer" << std::endl;
    m_asynXMysqls[id] = mysql;
    m_asynTools.push_back(mysql);
    return true;
}

bool Process::exeAsynSql(uint32_t id, const char* sql, std::function func)
{
    auto it = m_asynXMysqls.find(id);
    if (it == m_asynXMysqls.end()) {
        std::cout << "not find m_asynXMsql id = " << id << std::endl;
        return false;
    }
    std::cout << "exeAsynSql " << std::endl;
    return m_asynXMysqls[id]->exeAsynSql(sql, func);
}

bool Process::startAsynTools()
{
    for (auto tool : m_asynTools) {
        tool->run();
    }
    return true;
}


bool Process::stopAsynTools()
{
    for (auto tool : m_asynTools) {
        tool->stop();
    }
    return true;
}

④写一个测试看看 *** 作结果

        在XProcess中，增加回调函数void testAsynSql(XMysqlAsynRes* res), 在initProcess()中初始化异步数据库，在startProcess（）中调用异步数据库。

XProcess.cpp

#include "XProcess.h"
#include "../../proto/src/User.pb.h"
#include  
#include 
XProcess xprocess;

bool XProcess::initProcess()
{
    //加载数据库
    std::string host = getConfigValue("mysql", "host");
    std::string port = getConfigValue("mysql", "port");
    std::string user = getConfigValue("mysql", "user");
    std::string pwd = getConfigValue("mysql", "pwd");
    std::string db = getConfigValue("mysql", "db");
    std::string sqlType = getConfigValue("mysql", "type");
    uint32_t type = std::atoi(sqlType.c_str());
    if (!addMysqlServer(type, host.c_str(), port.c_str(), user.c_str(), pwd.c_str(), db.c_str())) {
        std::cout << "addMysqlServer error" << std::endl;
        return false;
    }

    //加载异步数据库
    if (!addAsynMysqlServer(type, host.c_str(), port.c_str(), user.c_str(), pwd.c_str(), db.c_str())) {
        std::cout << "addAsynMysqlServer error" << std::endl;
        return false;
    }

    //加载服务名字和类型
    std::string serverName = getConfigValue("server", "name");
    std::string serverType = getConfigValue("server", "type");
    std::string serverId = getConfigValue("server", "id");

    m_name = serverName;
    m_type = std::atoi(serverType.c_str());
    m_id = std::atoi(serverId.c_str());

    return true;
}

bool XProcess::startProcess()
{
    while (m_stop == false) {
        /*
        //获取系统时间戳
        time_t timeReal;
        time(&timeReal);
        timeReal = timeReal + 8 * 3600;
        tm* t = gmtime(&timeReal); 
        printf("%d-%02d-%02d %02d:%02d:%02d\n", t->tm_year + 1900, t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec); 
        */
        std::string sql = "select * from user_data;";
        std::cout << "exeAsynSql():" << sql << std::endl; 
        exeAsynSql(1, sql.c_str(), std::bind(&XProcess::testAsynSql, this, std::placeholders::_1));
        sleep(100);
    };
    return true;
}

bool XProcess::stopProcess()
{
 
    std::cout << "stop  " << m_name << std::endl; 
    m_stop = true;
    return true;
}

void XProcess::testAsynSql(XMysqlAsynRes* res)
{
    if (!res) {
        std::cout << "xmysqlAsyRes == nullptr" << std::endl;
    }
    std::cout << "XMysqlRes ------------" << std::endl;
    auto xRes = res->xMysqlRes;
    for (auto res : xRes.res) {
        for (auto row : res) {
            std::cout << row << " ";
        }
        std::cout << std::endl;
    }
    std::cout << "protoRes------------------- " << std::endl;
    std::vector> users;
    res->getProtoRes(users);
    for (auto u : users) {
        std::cout << u->id() << u->nickname() << std::endl;
    }
}

⑤看一下测试结果

 3.小结

    ①统一管理这些异步工具

        在关闭和运行这些工具的时候，需要统一处理，这样可以让流程更清晰，如果主进程关闭，工具没有关闭，那整个进程就会陷入死锁状态。

   ②数据库 *** 作的坑

        mysql提供访问数据库结果的接口是mysql_fetch_row（MYSQL_RES*）,这个函数会根据结果集，从头到尾访问，如果访问到结尾了，那需要重置一下访问的光标位置，这里就要用到mysql_data_seek(MYSQL_RES* , uint32_t row);函数，这个函数会改变结果集的遍历位置。