源码如下：

util_timer.h

#ifndef LST_TIMER
#define LST_TIMER


#include <time.h>
#include <sys/time.h>
#include <stdlib.h>
#include <signal.h>




#define BUFFER_SIZE 64
struct util_timer;


/*
struct client_data{
sockaddr_in address;
int sockfd;
char buf[BUFFER_SIZE];
util_timer * timer;
};
*/


struct util_timer{
time_t expire;
// client_data * user_data;
char *buffer;
struct util_timer *prev;
struct util_timer *next;
};


struct timer_lst{
struct util_timer * head;
struct util_timer * tail;
};




void cb_func(unsigned char *userdata);
void add_timer2(struct util_timer * timer, struct util_timer *lst_head);
void add_timer(struct util_timer *timer);
void adjust_timer(struct util_timer *timer);
void del_timer(struct util_timer * timer);
void tick();


#endif

util_timer.c

#include "util_timer.h"


struct util_timer * head;
struct util_timer * tail;




void print_hex_ex(unsigned char *buf, int len)
{
    int i, n;
    printf("            0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F");
    n = 0;
    for (i=0; i<len; i++)
    {
        if (i % 0x10 == 0) {
            printf("\n%08Xh: ", i);
        }
        printf("%02X ", buf[i]);
    }
printf("\nlens:%d\n\n",len);
}


void cb_func(unsigned char *userdata){
print_hex_ex(userdata, 8);
return;
}


void add_timer2(struct util_timer * timer, struct util_timer * lst_head){
struct util_timer * prev = lst_head;
struct util_timer * tmp = prev->next;
while(tmp){
if(timer->expire < tmp->expire ){
prev->next = timer;
timer->next =tmp;
tmp->prev = timer;
timer->prev = prev;
break;
}
prev = tmp;
tmp = tmp->next;
}
if(!tmp){
prev->next = timer;
timer->prev = prev;
timer->next = NULL;
tail = timer;
}

}


void add_timer(struct util_timer *timer){
if(!timer){
return;
}

if(!head){
head = tail = timer;
return ;
}

if(timer->expire < head->expire){
timer->next = head;
head->prev = timer;
head = timer;

return;
}

add_timer2(timer, head);

}


void adjust_timer(struct util_timer *timer){
if(!timer){
return;
}
struct util_timer * tmp = timer->next;
if(!tmp || (timer->expire < tmp->expire)){
return;
}
if(timer == head){
head = head->next;
head->prev = NULL;
timer->next = NULL;
add_timer2(timer, head);
}else{
timer->prev->next = timer->next;
timer->next->prev = timer->prev;
add_timer2(timer, timer->next);
}

}


void del_timer(struct util_timer * timer){
if(!timer){
return;
}
if((timer == head) && (timer == tail)){
free(timer);
head = NULL;
tail = NULL;
return;
}
if(timer == head){
head = head->next;
head->prev = NULL;
free(timer);
return;
}
if(timer == tail){
tail = tail ->prev;
tail->next = NULL;
free(timer);
return;
}

timer->prev->next = timer->next;
    timer->next->prev = timer->prev;
free(timer);

}


void tick(){
if( !head )
     {
        return;
     }
     printf( "timer tick\n" );
     time_t cur = time( NULL );
     struct util_timer* tmp = head;
     while( tmp )
     {
         if( cur < tmp->expire )
         {
printf("tmp->expire is not chaoshi\n");
             break;
         }
cb_func( tmp->buffer );
         head = tmp->next;
         if( head )
         {
             head->prev = NULL;
         }
         free(tmp);
         tmp = head;
     }

}






int main(){
int i;
char *tmpbuf[5]={"aaaaaaaa","bbbbbbbb","cccccccc","dddddddd","eeeeeeee"};
head = NULL;
tail = NULL;
time_t cur = time(NULL);
for(i = 0; i<5; i++){

struct util_timer *timer = NULL ;
timer = (struct util_timer *)malloc(sizeof(struct util_timer)*1);
cur = cur + 1;
timer->expire = cur;
timer->buffer = tmpbuf[i];
add_timer(timer);
}

printf("sleep begin \n");
sleep(3);
printf("sleep end \n");

tick();
}

编译gcc -o util_timer util_timer.c

运行./util_timer

输出：

[root@hsm timer_test]# ./util_timer
sleep begin 
sleep end 
timer tick
            0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
00000000h: 61 61 61 61 61 61 61 61 
lens:8


            0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
00000000h: 62 62 62 62 62 62 62 62 
lens:8


            0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
00000000h: 63 63 63 63 63 63 63 63 
lens:8


tmp->expire is not chaoshi

总结：链表共五个节点，每个节点相差1秒，按时间大小升序排列，链表头时间节点最小，依次递增。tick函数只处理链表中已经超时的节点，并打印buffer里的值。当休眠3秒时，链表中的前3个节点已经超时，剩下的2个节点没有超时，所以只打印前三个节点。