Linux网络编程之定时器

定时器的头文件lst_timer.h

#ifndef LST_TIMER
#define LST_TIMER

#include <time.h>

#define BUFFER_SIZE 64
class util_timer;
struct client_data //数据域的结构
{
    sockaddr_in address;
    int sockfd;
    char buf[ BUFFER_SIZE ];
    util_timer* timer;
};

class util_timer //定时器类
{
public:
    util_timer() : prev( NULL ), next( NULL ){}

public:
   time_t expire; 
   void (*cb_func)( client_data* ); //回调函数指针（指向函数的指针变量）
   client_data* user_data;
   util_timer* prev;
   util_timer* next;
};

class sort_timer_lst //按升序构造的定时器类
{
public:
    sort_timer_lst() : head( NULL ), tail( NULL ) {} //初始化两个指针
    ~sort_timer_lst()
    {
        util_timer* tmp = head;
        while( tmp ) //循环删除节点
        {
            head = tmp->next;
            delete tmp;
            tmp = head;
        }
    }
    void add_timer( util_timer* timer )
    {
        if( !timer ) //传入的定时器结构为空，处理方式
        {
            return;
        }
        if( !head ) //空表的处理方式
        {
            head = tail = timer;
            return; 
        }
        if( timer->expire < head->expire ) //timer的定时期限比head小的话，头插
        {
            timer->next = head;
            head->prev = timer;
            head = timer;
            return;
        }
        add_timer( timer, head ); //否则正常插入，调用添加函数add_timer
    }
    void adjust_timer( util_timer* timer ) //将需要调整的函数从双向链表中断开，再分情况处理
    {
        if( !timer )
        {
            return;
        }
        util_timer* tmp = timer->next;
        if( !tmp || ( timer->expire < tmp->expire ) )
        {
            return;
        }
        if( timer == head ) //要调整的节点是head的情况
        {
            head = head->next;
            head->prev = NULL;
            timer->next = NULL;
            add_timer( timer, head );
        }
        else //要调整的节点不是head
        {
            timer->prev->next = timer->next;
            timer->next->prev = timer->prev;
            add_timer( timer, timer->next ); //timer.expire改变之后，从新添加顺序
        }
    }
    void del_timer( util_timer* timer )
    {
        if( !timer ) //要删除的节点为空时
        {
            return;
        }
        if( ( timer == head ) && ( timer == tail ) ) //链表中只有一个节点要删除的时候
        {
            delete timer;
            head = NULL;
            tail = NULL;
            return;
        }
        if( timer == head ) //头删
        {
            head = head->next;
            head->prev = NULL;
            delete timer;
            return;
        }
        if( timer == tail ) //尾删
        {
            tail = tail->prev;
            tail->next = NULL;
            delete timer;
            return;
        }
        timer->prev->next = timer->next; //删除节点在中间时候正常删除
        timer->next->prev = timer->prev;
        delete timer;
    }
    void tick() //心跳函数
    {
        if( !head )
        {
            return;
        }
        printf( "timer tick\n" ); //链表不为空的话
        time_t cur = time( NULL ); //获取当前时间
        util_timer* tmp = head;  
        while( tmp )
        {
            if( cur < tmp->expire )
            {
                break;
            }
            tmp->cb_func( tmp->user_data ); //执行回调函数
            head = tmp->next;
            if( head )
            {
                head->prev = NULL;
            }
            delete tmp; //执行完回调函数之后，删除掉节点
            tmp = head;
        }
    }

private:
    void add_timer( util_timer* timer, util_timer* lst_head )
    {
        util_timer* prev = lst_head;
        util_timer* tmp = prev->next;
        while( tmp )
        {
            if( timer->expire < tmp->expire ) //满足条件才能往pre和tmp中间插入
            {
                prev->next = timer;
                timer->next = tmp;
                tmp->prev = timer;
                timer->prev = prev;
                break;
            }
            prev = tmp;
            tmp = tmp->next;
        }
        if( !tmp ) //尾插节点
        {
            prev->next = timer;
            timer->prev = prev;
            timer->next = NULL;
            tail = timer;
        }
        
    }

private:
    util_timer* head; //前驱指针
    util_timer* tail; //后继指针
};

#endif

本定时器代码来源于《Linux高性能服务器》一书，程序注释为博主所注。