三、Lars系统-DNSService - 第20章-Dns中Route结构的定义 - 《Lars-基于C 负载均衡远程服务器调度系统》

20.1 Route类的单例模式设计
20.2 Route中的map数据类型定义
20.3 Route初始化
20.4 测试Route的构造及map加载

20.1 Route类的单例模式设计

    首先我们将Route类设计成单例，我们创建头文件和cpp文件.

lars_dns/include/dns_route.h

#pragma once
class Route
{
    public:
    //创建单例的方法
    static void init() {
        _instance = new Route(); 
    }
    static Route *instance() {
        //保证init方法在这个进程执行中，只执行一次
        pthread_once(&_once, init);
        return _instance;
    }
    private:
    //构造函数私有化
    Route();
    Route(const Route&);
    const Route& operator=(const Route&);
    //单例
    static Route* _instance;
    //单例锁
    static pthread_once_t _once;
    /* ---- 属性 ---- */
    //...
};
lars_dns/src/dns_route.cpp
#include "dns_route.h"
//单例对象
Route * Route::_instance = NULL;
//用于保证创建单例的init方法只执行一次的锁
pthread_once_t Route::_once = PTHREAD_ONCE_INIT;

20.2 Route中的map数据类型定义

    **这里的Route并非reactor中的router，这里的Route我们是把modid/cmdid与需要管理的远程服务器的serverip/serverport的一条对应关系叫一个Route。**<br />        我们用map来存储这些关系，其中key是modid/cmdid的一个二进制偏移量处理，而map的value是一个set集合，因为一个modid/cmdid可能对应多个host主机的ip和端口。具体的表现数据结构形式如下。<br />![](https://cdn.nlark.com/yuque/0/2022/jpeg/26269664/1650026084823-95c12039-8209-4436-90ce-f8ff568e34ef.jpeg#clientId=ud5fcc95a-e218-4&crop=0&crop=0&crop=1&crop=1&from=paste&id=u28833435&margin=%5Bobject%20Object%5D&originHeight=768&originWidth=1024&originalType=url&ratio=1&rotation=0&showTitle=false&status=done&style=none&taskId=uebf25851-125a-4a07-8b47-d59fa7a647f&title=)<br />        接下来，我们来定义一个相关代码：

lars_dns/include/dns_route.h

#pragma once
#include <pthread.h>
#include <ext/hash_map>
#include <ext/hash_set>
#include "mysql.h"
using __gnu_cxx::hash_map;
using __gnu_cxx::hash_set;
//定义用来保存modID/cmdID与host的IP/host的port的对应的关系 数据类型  
typedef hash_map< uint64_t, hash_set<uint64_t> > route_map;
typedef hash_map< uint64_t, hash_set<uint64_t> >::iterator route_map_it;
//定义用来保存host的IP/host的port的的集合 数据类型
typedef hash_set<uint64_t> host_set;
typedef hash_set<uint64_t>::iterator host_set_it;
class Route
{
public:
    //创建单例的方法
    static void init() {
        _instance = new Route(); 
    }
    static Route *instance() {
        //保证init方法在这个进程执行中，只执行一次
        pthread_once(&_once, init);
        return _instance;
    }
private:
    //构造函数私有化
    Route();
    Route(const Route&);
    const Route& operator=(const Route&);
    //单例
    static Route* _instance;
    //单例锁
    static pthread_once_t _once;
    /* ---- 属性 ---- */
    //数据库
    MYSQL _db_conn;  //mysql链接  
    char _sql[1000]; //sql语句
    //modid/cmdid---ip/port 对应的route关系map
    route_map *_data_pointer; //指向RouterDataMap_A 当前的关系map
    route_map *_temp_pointer; //指向RouterDataMap_B 临时的关系map
    pthread_rwlock_t _map_lock;
};

20.3 Route初始化

lars_dns/src/dns_route.cpp

#include <string>
#include <stdlib.h>
#include <unistd.h>
#include "lars_reactor.h"
#include "dns_route.h"
#include "string.h"
using namespace std;
//单例对象
Route * Route::_instance = NULL;
//用于保证创建单例的init方法只执行一次的锁
pthread_once_t Route::_once = PTHREAD_ONCE_INIT;
Route::Route()
{
    //1 初始化锁
    pthread_rwlock_init(&_map_lock, NULL);
    //2 初始化map
    _data_pointer = new route_map();//RouterDataMap_A
    _temp_pointer = new route_map();//RouterDataMap_B
    //3 链接数据库
    this->connect_db();
    //4 查询数据库，创建_data_pointer 与 _temp_pointer 两个map
    this->build_maps();
}
void Route::connect_db() 
{
    // --- mysql数据库配置---
    string db_host = config_file::instance()->GetString("mysql", "db_host", "127.0.0.1");
    short db_port = config_file::instance()->GetNumber("mysql", "db_port", 3306);
    string db_user = config_file::instance()->GetString("mysql", "db_user", "root");
    string db_passwd = config_file::instance()->GetString("mysql", "db_passwd", "aceld");
    string db_name = config_file::instance()->GetString("mysql", "db_name", "lars_dns");
    mysql_init(&_db_conn);
    //超时断开
    mysql_options(&_db_conn, MYSQL_OPT_CONNECT_TIMEOUT, "30");
    //设置mysql链接断开后自动重连
    my_bool reconnect = 1; 
    mysql_options(&_db_conn, MYSQL_OPT_RECONNECT, &reconnect);
    if (!mysql_real_connect(&_db_conn, db_host.c_str(), db_user.c_str(), db_passwd.c_str(), db_name.c_str(), db_port, NULL, 0)) {
        fprintf(stderr, "Failed to connect mysql\n");
        exit(1);
    }
}
void Route::build_maps()
{
    int ret = 0;
    snprintf(_sql, 1000, "SELECT * FROM RouteData;");
    ret = mysql_real_query(&_db_conn, _sql, strlen(_sql));
    if ( ret != 0) {
        fprintf(stderr, "failed to find any data, error %s\n", mysql_error(&_db_conn));
        exit(1);
    }
    //得到结果集
    MYSQL_RES *result = mysql_store_result(&_db_conn);
    //得到行数
    long line_num = mysql_num_rows(result);
    MYSQL_ROW row;
    for (long i = 0; i < line_num; i++) {
        row = mysql_fetch_row(result);
        int modID = atoi(row[1]);
        int cmdID = atoi(row[2]);
        unsigned ip = atoi(row[3]);
        int port = atoi(row[4]);
        //组装map的key，有modID/cmdID组合
        uint64_t key = ((uint64_t)modID << 32) + cmdID;
        uint64_t value = ((uint64_t)ip << 32) + port;
        printf("modID = %d, cmdID = %d, ip = %lu, port = %d\n", modID, cmdID, ip, port);
        //插入到RouterDataMap_A中
        (*_data_pointer)[key].insert(value);
    }
    mysql_free_result(result);
}

20.4 测试Route的构造及map加载

完成lars dns-service V0.1版本测试
我们在Lars/base/sql加入几个简单插入数据的sql语句，方便数据库里有一些测试数据，我们之后应该会提供一个web管理端来操作数据库。

Lars/base/sql/dns_route_insert.sql

USE lars_dns;
INSERT INTO RouteData(modid, cmdid, serverip, serverport) VALUES(1, 1, 3232235953, 7777);
INSERT INTO RouteData(modid, cmdid, serverip, serverport) VALUES(1, 2, 3232235954, 7776);
INSERT INTO RouteData(modid, cmdid, serverip, serverport) VALUES(1, 2, 3232235955, 7778);
INSERT INTO RouteData(modid, cmdid, serverip, serverport) VALUES(1, 2, 3232235956, 7779);
UPDATE RouteVersion SET version = UNIX_TIMESTAMP(NOW()) WHERE id = 1;
Lars/base/sql/dns_route_drop.sql
USE lars_dns;
DELETE FROM RouteData;
UPDATE RouteVersion SET version = UNIX_TIMESTAMP(NOW()) WHERE id = 1;

    先将测试数据导入数据库。然后回到lars_dns下编译。执行

$./bin/lars_dns 
msg_router init...
create 0 thread
create 1 thread
create 2 thread
create 3 thread
create 4 thread
modID = 1, cmdID = 1, ip = 3232235953, port = 7777
modID = 1, cmdID = 2, ip = 3232235954, port = 7776
modID = 1, cmdID = 2, ip = 3232235955, port = 7778
modID = 1, cmdID = 2, ip = 3232235956, port = 7779
lars dns service ....