MySQL:如何编写daemon plugin(12)

              PLUGIN_VAR_OPCMDARG, 

              "disable monitor  if 0,default TRUE", 

              NULL, NULL, TRUE); 

struct st_mysql_sys_var*vars_system_var[] = { 

        MYSQL_SYSVAR(monitors_state), 

            NULL 

}; 

/*创建status变量，可通过showstatus查看*/ 

static structst_mysql_show_var sys_status_var[] = 

{ 

    {"monitor_num", (char *)&monitor_num, SHOW_LONG}, 

    {0, 0, 0} 

}; 

/*线程函数，后台线程启动后，会持续执行该函数*/ 

pthread_handler_tmonitoring(void *p) 

{ 

    char buffer[MONITORING_BUFFER]; 

    char time_str[20]; 

while(1) { 

/*每隔5秒记录一次，我们也可以把5修改为一个可配置的系统变量*/ 

        sleep(5); 

        if (!monitor_state) 

            continue; 

        monitor_num++; 

/*获取当前时间，mysql自有函数*/ 

        get_date(time_str, GETDATE_DATE_TIME,0); 

        snprintf(buffer, MONITORING_BUFFER,"%s: %u of %lu clients connected, " 

                "%lu connections made\n", 

                time_str, thread_count, 

                max_connections, thread_id); 

/*使用getrusage函数来获得当前进程的运行状态，具体man getrusage*/ 

        if (getrusage(RUSAGE_SELF, &usage)== 0){ 

            snprintf(buffer+strlen(buffer) , 

MONITORING_BUFFER, "user time:%d,system time:%d," 

                                                "maxrss:%d,ixrss:%d,idrss:%d,"