C语言实现一个简单的多定时器 |
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一、C语言实现一个简单的多定时器 1、实现细节 这个实现允许用户使用多个自定义的定时器，每个自定义的定时器将周期地被触发直到其被删除。实现的主要思路是： 1）首先在初始化多定时器（init_mul_timer）时利用setitimer注册一个基本的时间单位（如1s）的定时事件； 2）用户需要set_a_timer注册自定义定时器时，在timer_manage管理结构中记录这个定时器的回调函数和定时周期等参数； 3）当基本的时间单位到期后（如SIGALRM信号到达时），遍历整个timer_manage，如果有自定义定时器的超时时间到了，就执行相应的回调函数，并将自定义定时器的超时时间置为最初值；否则将自定义定时器的超时时间相应地减一个基本的时间单位； 4）用户通过del_a_timer来删除某个定时器，通 过destroy_mul_timer来删除整个多定时器。 2、代码 i) mul_timer.h #ifndef _MUL_TIMER_H_ #define _MUL_TIMER_H_ #include #define MAX_TIMER_CNT 10 #define MUL_TIMER_RESET_SEC 10 #define TIMER_UNIT 60 #define MAX_FUNC_ARG_LEN 100 #define INVALID_TIMER_HANDLE (-1) typedef int timer_handle_t; typedef struct _timer_manage { struct _timer_info { int state; /* on or off */ int interval; int elapse; /* 0~interval */ int (* timer_proc) (void *arg, int arg_len); char func_arg[MAX_FUNC_ARG_LEN]; int arg_len; }timer_info[MAX_TIMER_CNT]; void (* old_sigfunc)(int); void (* new_sigfunc)(int); struct itimerval value, ovalue; }_timer_manage_t; /* success, return 0; failed, return -1 */ int init_mul_timer(void); /* success, return 0; failed, return -1 */ int destroy_mul_timer(void); /* success, return timer handle(>=0); failed, return -1 */ timer_handle_t set_a_timer(int interval, int (* timer_proc) (void *arg, int arg_len), void *arg, int arg_len); /* success, return 0; failed, return -1 */ int del_a_timer(timer_handle_t handle); #endif /* _MUL_TIMER_H_ */ii)mul_timer.c #include #include #include #include #include "mul_timer.h" static struct _timer_manage timer_manage; static void sig_func(int signo); /* success, return 0; failed, return -1 */ int init_mul_timer(void) { int ret; memset(&timer_manage, 0, sizeof(struct _timer_manage)); if( (timer_manage.old_sigfunc = signal(SIGALRM, sig_func)) == SIG_ERR) { return (-1); } timer_manage.new_sigfunc = sig_func; timer_manage.value.it_value.tv_sec = MUL_TIMER_RESET_SEC; timer_manage.value.it_value.tv_usec = 0; timer_manage.value.it_interval.tv_sec = TIMER_UNIT; timer_manage.value.it_interval.tv_usec = 0; ret = setitimer(ITIMER_REAL, &timer_manage.value, &timer_manage.ovalue); return (ret); } /* success, return 0; failed, return -1 */ int destroy_mul_timer(void) { int ret; if( (signal(SIGALRM, timer_manage.old_sigfunc)) == SIG_ERR) { return (-1); } ret = setitimer(ITIMER_REAL, &timer_manage.ovalue, &timer_manage.value); if(ret int i; if(timer_proc == NULL || interval if(timer_manage.timer_info[i].state == 1) { continue; } memset(&timer_manage.timer_info[i], 0, sizeof(timer_manage.timer_info[i])); timer_manage.timer_info[i].timer_proc = timer_proc; if(arg != NULL) { if(arg_len > MAX_FUNC_ARG_LEN) { return (-1); } memcpy(timer_manage.timer_info[i].func_arg, arg, arg_len); timer_manage.timer_info[i].arg_len = arg_len; } timer_manage.timer_info[i].interval = interval; timer_manage.timer_info[i].elapse = 0; timer_manage.timer_info[i].state = 1; break; } if(i >= MAX_TIMER_CNT) { return (-1); } return (i); } /* success, return 0; failed, return -1 */ int del_a_timer(timer_handle_t handle) { if(handle = MAX_TIMER_CNT) { return (-1); } memset(&timer_manage.timer_info[handle], 0, sizeof(timer_manage.timer_info[handle])); return (0); } static void sig_func(int signo) { int i; for(i = 0; i continue; } timer_manage.timer_info[i].elapse++; if(timer_manage.timer_info[i].elapse == timer_manage.timer_info[i].interval) { timer_manage.timer_info[i].elapse = 0; timer_manage.timer_info[i].timer_proc(timer_manage.timer_info[i].func_arg, timer_manage.timer_info[i].arg_len); } } } #define _MUL_TIMER_MAIN #ifdef _MUL_TIMER_MAIN static void get_format_time(char *tstr) { time_t t; t = time(NULL); strcpy(tstr, ctime(&t)); tstr[strlen(tstr)-1] = '/0'; return; } timer_handle_t hdl[3], call_cnt = 0; int timer_proc1(void *arg, int len) { char tstr[200]; static int i, ret; get_format_time(tstr); printf("hello %s: timer_proc1 is here./n", tstr); if(i >= 5) { get_format_time(tstr); ret = del_a_timer(hdl[0]); printf("timer_proc1: %s del_a_timer::ret=%d/n", tstr, ret); } i++; call_cnt++; return (1); } int timer_proc2(void * arg, int len) { char tstr[200]; static int i, ret; get_format_time(tstr); printf("hello %s: timer_proc2 is here./n", tstr); if(i >= 5) { get_format_time(tstr); ret = del_a_timer(hdl[2]); printf("timer_proc2: %s del_a_timer::ret=%d/n", tstr, ret); } i++; call_cnt++; return (1); } int main(void) { char arg[50]; char tstr[200]; int ret; init_mul_timer(); hdl[0] = set_a_timer(2, timer_proc1, NULL, 0); printf("hdl[0]=%d/n", hdl[0]); hdl[1] = set_a_timer(3, timer_proc2, arg, 50); printf("hdl[1]=%d/n", hdl[1]); hdl[2] = set_a_timer(3, timer_proc2, arg, 101); printf("hdl[1]=%d/n", hdl[2]); while(1) { if(call_cnt >= 12) { get_format_time(tstr); ret = destroy_mul_timer(); printf("main: %s destroy_mul_timer, ret=%d/n", tstr, ret); call_cnt++; } if(call_cnt >= 20) { break; } } return 0; } #endif3、缺陷 1)新建定时器、遍历定时器和删除定时器（查找哪个定时器超时）时时间复杂度都为O(n)（n是定时器的个数）; 2)适用环境是单线程环境，如要用于多线程，需添加同步操作。 3)程序中有些小bug，如对新建超时时间为0的定时器没有妥善的处理。 二、改进版 1、思路 改进定时器的实现，即是改善二种所指出的几个缺陷，如下是一个改进版,主要是将遍历超时时间的时间复杂度降为了O(1). 改善思路:各定时器以一个链表的形式组织起来,除链表头定时器的超时时间是用绝对时间纪录的外,其它定时器的超时时间均用相对时间(即超时时间-前一个定时器的超时时间)纪录. 注意,各定时器都是一次性的,当定时器的超时被处理后,定时器将被自动删除.另外如果将定时器的结点改为双向结构,可以将删除定时器的时间复杂度降为O(1). 2、数据结构 每个定时器都有一个唯一的ID,这个ID是如下的结构体: typedef struct _timer_handle { unsigned long ptr; unsigned long entry_id; }*timer_handle_t;ptr纪录的是定时器结点的地址,entry_id则是一个自多定时器初始化后自增的id.ptr和entry_id一起组成定时器结点的key,一方面使得新建定时器时生成key的过程大为简化,另一方面使得删除定时器的时间复杂度降为O(1)（前提是定时器结点采用双向结构）。 定时器结点的数据结构如下： /* timer entry */ typedef struct _mul_timer_entry { char is_use; /* 0, not; 1, yes */ struct _timer_handle handle; unsigned int timeout; unsigned int elapse; /* */ int (* timer_proc) (void *arg, unsigned int *arg_len); /* callback function */ void *arg; unsigned int *arg_len; struct _mul_timer_entry *etr_next; }mul_timer_entry_t;其中的is_use是用来防止这样一种情况：用户在回调函数中调用kill_timer来删除定时器，这个时候kill_timer和遍历定时器中都有删除结点的操作，有可能将整个链表搞混乱。所以在调用用户的回调函数前先将is_use置1，在kill_timer中需检查is_use，只有在 is_use为0的情况下，才执行清理定时器结点的操作。 3、代码（windows版） i)mul_timer.h #ifndef _MUL_TIMER_H_ #define _MUL_TIMER_H_ #include typedef struct _timer_handle { unsigned long ptr; unsigned long entry_id; }*timer_handle_t; /* timer entry */ typedef struct _mul_timer_entry { char is_use; /* 0, not; 1, yes */ struct _timer_handle handle; unsigned int timeout; unsigned int elapse; /* */ int (* timer_proc) (void *arg, unsigned int *arg_len); /* callback function */ void *arg; unsigned int *arg_len; struct _mul_timer_entry *etr_next; }mul_timer_entry_t; typedef struct _mul_timer_manage { unsigned long entry_id; unsigned int timer_cnt; unsigned int time_unit; struct _mul_timer_entry *etr_head; UINT timer_id; }; struct _mul_timer_manage *init_mul_timer(unsigned int time_unit); timer_handle_t set_timer(struct _mul_timer_manage *ptimer, unsigned int time_out, int (* timer_proc) (void *arg, unsigned int *arg_len), void *arg, unsigned int *arg_len); int kill_timer(struct _mul_timer_manage *ptimer, timer_handle_t hdl); int get_timeout_byhdl(struct _mul_timer_manage *ptimer, timer_handle_t hdl); int get_timeout_bytimeproc(struct _mul_timer_manage *ptimer, int (* timer_proc) (void *arg, unsigned int *arg_len)); int release_mul_timer(struct _mul_timer_manage *ptimer); int is_valid_time_hdl(timer_handle_t hdl); #endif /* _MUL_TIMER_H_ */ii)mul_timer.c #include "mul_timer.h" #include #include #include void CALLBACK traverse_mul_timer(UINT uTimerID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2); static int print_mul_timer(struct _mul_timer_manage *ptimer); struct _mul_timer_manage *init_mul_timer(unsigned int time_unit) { struct _mul_timer_manage *p; if( (p = malloc(sizeof(struct _mul_timer_manage))) == NULL) { return (NULL); } p->etr_head = NULL; p->timer_cnt = 0; p->time_unit = time_unit; p->entry_id = 0; p->timer_id = timeSetEvent(time_unit, 0, (LPTIMECALLBACK )traverse_mul_timer, (DWORD)p, TIME_PERIODIC); return(p); } timer_handle_t set_timer(struct _mul_timer_manage *ptimer, unsigned int time_out, int (* timer_proc) (void *arg, unsigned int *arg_len), void *arg, unsigned int *arg_len) { struct _mul_timer_entry *p, *prev, *pnew; if(ptimer == NULL || time_out == 0) { return (NULL); } if( (pnew = malloc(sizeof(struct _mul_timer_entry))) == NULL) { return (NULL); } pnew->is_use = 0; pnew->arg = arg; pnew->arg_len = arg_len; pnew->elapse = 0; pnew->timer_proc = timer_proc; p = ptimer->etr_head; prev = NULL; while(p != NULL) { if(p->timeout p->timeout -= time_out; break; } } pnew->timeout = time_out; pnew->etr_next = p; pnew->handle.ptr = (unsigned long )pnew; pnew->handle.entry_id = ptimer->entry_id; ptimer->entry_id++; if(prev == NULL) { ptimer->etr_head = pnew; } else { prev->etr_next = pnew; } ptimer->timer_cnt++; return (&pnew->handle); } int kill_timer(struct _mul_timer_manage *ptimer, timer_handle_t hdl) { struct _mul_timer_entry *p, *prev; if(ptimer == NULL) { return (0); } p = ptimer->etr_head; prev = NULL; while(p != NULL) { if(p->handle.ptr == hdl->ptr && p->handle.entry_id == hdl->entry_id) { break; } prev = p; p = p->etr_next; } /* no such timer or timer is in use, return 0 */ if(p == NULL || (p != NULL && p->is_use == 1)) { return (0); } /* has found the timer */ if(prev == NULL) { ptimer->etr_head = p->etr_next; } else { prev->etr_next = p->etr_next; } /* revise timeout */ if(p->etr_next != NULL) { p->etr_next->timeout += p->timeout; } /* delete the timer */ free(p); p = NULL; ptimer->timer_cnt--; return (1); } int get_timeout_byhdl(struct _mul_timer_manage *ptimer, timer_handle_t hdl) { struct _mul_timer_entry *p; unsigned int timeout; if(ptimer == NULL || (struct _mul_timer_entry *)(hdl) == NULL) { return (-1); } timeout = 0; p = ptimer->etr_head; while(p != NULL) { if(p->handle.ptr == hdl->ptr && p->handle.entry_id == hdl->entry_id) { break; } timeout += p->timeout; p = p->etr_next; } if(p == NULL) { return (-1); } else { return ((int)timeout+p->timeout); } } int get_timeout_bytimeproc(struct _mul_timer_manage *ptimer, int (* timer_proc) (void *arg, unsigned int *arg_len)) { struct _mul_timer_entry *p; unsigned int timeout; if(ptimer == NULL || timer_proc == NULL) { return (-1); } p = ptimer->etr_head; while((p != NULL) && (p->timer_proc != timer_proc)) { timeout += p->timeout; p = p->etr_next; } if(p == NULL) { return (-1); } else { return (timeout+p->timeout); } } int release_mul_timer(struct _mul_timer_manage *ptimer) { struct _mul_timer_entry *p, *ptmp; if(ptimer == NULL) { return (0); } timeKillEvent(ptimer->timer_id); /* delete all timers */ p = ptimer->etr_head; while(p != NULL) { ptmp = p; p = p->etr_next; free(ptmp); } /* delete timer_manage */ free(ptimer); ptimer = NULL; return (1); } int is_valid_time_hdl(timer_handle_t hdl) { if(hdl == NULL) { return (0); } else { return (1); } } void CALLBACK traverse_mul_timer(UINT uTimerID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2) { struct _mul_timer_manage *ptimer; struct _mul_timer_entry *p, *ptmp; unsigned int timeout; ptimer = (struct _mul_timer_manage *)dwUser; if(ptimer == NULL) { return; } timeout = ptimer->time_unit; p = ptimer->etr_head; while(p != NULL) { if(p->timeout p->timeout -= timeout; p->elapse += timeout; ptimer->etr_head = p; break; } } if(p == NULL) { ptimer->etr_head = NULL; } return; } static int print_mul_timer(struct _mul_timer_manage *ptimer) { struct _mul_timer_entry *p; int i; if(ptimer == NULL) { return (0); } printf("***************************mul_timer statistics start************************/n"); printf("this mul_timer's time_unit=%u, etr_head=%p and has %d timers:/n", ptimer->time_unit, ptimer->etr_head, ptimer->timer_cnt); p = ptimer->etr_head; i = 0; while(p != NULL) { printf("the %d timer: timeout=%u, elapse=%u, timer_proc=%p, arg=%p, arg_len=%p, etr_next=%p/n" , i+1, p->timeout, p->elapse, p->timer_proc, p->arg, p->arg_len, p->etr_next); p = p->etr_next; i++; } printf("***************************mul_timer statistics end************************/n"); return (1); } #define _MUL_TIMER_MAIN #ifdef _MUL_TIMER_MAIN static void get_format_time(char *tstr) { time_t t; t = time(NULL); strcpy(tstr, ctime(&t)); tstr[strlen(tstr)-1] = '/0'; return; } timer_handle_t hdl[100]; int call_cnt = 0; struct _mul_timer_manage *ptimer; int timer_proc1(void *arg, unsigned int *len) { char tstr[200]; static int i, ret; get_format_time(tstr); printf("call_cnt=%d, hello %s: timer_proc1 is here./n", call_cnt, tstr); i++; call_cnt++; return (1); } int timer_proc2(void * arg, unsigned int *len) { char tstr[200]; static int i, ret; get_format_time(tstr); printf("call_cnt=%d, hello %s: timer_proc2 is here: arg = %s, len = %d./n", call_cnt, tstr, arg, *len); i++; call_cnt++; return (1); } int main(void) { char arg[50] = "hello, multiple timers"; char tstr[200]; int ret; int len = 50, i; ptimer = init_mul_timer(1000); for(i = 0; i if(call_cnt == 15) { get_format_time(tstr); ret = release_mul_timer(ptimer); printf("call_cnt=%d, main: %s destroy_mul_timer, ret=%d/n", call_cnt, tstr, ret); call_cnt++; } } return 0; } #endif3、缺陷 1)新建定时器的时间复杂度为O(n),删除定时器的时间复杂度也为O(n)(简单地将定时器结点改为双向结构,可将复杂度降为O(1)); 2)不能用于多线程环境 |
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