前言：
linux下，定时器有三种实现：
1）使用posix的定时器，相关接口为 timer_create
2）使用alarm函数进行计时，alarm函数计时满后会发送ALARM信号，注册信号处理函数即可；
3）使用linux内核的原生timer，需要引入内核模块，头文件为 linux/timer.h
C++ 封装posix：
template <typename T>
class MyTimer
{
public:
typedef void (*TimerHandler)(union sigval);
public:
MyTimer();
~MyTimer();
void Init(bool triggeronstart,long long interval,TimerHandler routine,std::shared_ptr<T> routineArgs,std::string desc);
void Delete();
public:
std::string m_desc;
private:
TimerHandler m_routine;
bool m_triggerOnStart = false;
long long m_interval; //ms
timer_t m_timerid;
std::shared_ptr<T> m_routineArgs;
};
template <typename T>
MyTimer<T>::MyTimer()
{
}
template <typename T>
MyTimer<T>::~MyTimer()
{
}
template <typename T>
void MyTimer<T>::Init(bool triggeronstart,long long interval,TimerHandler routine,std::shared_ptr<T> routineArgs,std::string desc)
{
m_triggerOnStart = triggeronstart;
m_interval = interval;
m_routine = routine;
m_routineArgs = routineArgs;
m_desc = desc;
int ret = 0;
struct sigevent sev;
memset(&sev, 0, sizeof(struct sigevent));
sev.sigev_notify = SIGEV_THREAD;
sev.sigev_notify_function = m_routine;
sev.sigev_value.sival_ptr = m_routineArgs.get();
if(ret = timer_create(CLOCK_REALTIME,&sev,&m_timerid))
{
assert(ret);
}
struct itimerspec its;
its.it_interval.tv_sec = m_interval/1000;
its.it_interval.tv_nsec = (m_interval%1000)*1000000;
if(m_triggerOnStart){
its.it_value.tv_sec = 0;
its.it_value.tv_nsec = 0;
}else{
its.it_value.tv_sec = its.it_interval.tv_sec;
its.it_value.tv_nsec = its.it_interval.tv_nsec;
}
if(ret = timer_settime(m_timerid, 0, &its, NULL))
{
assert(ret);
}
}
template <typename T>
void MyTimer<T>::Delete()
{
timer_delete(m_timerid);
}
posix：
以下代码使用回调函数作为定时器触发处理手段。
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <signal.h>
struct param{
int i;
char c;
}p;
int cnt;
void callback(union sigval v){
struct param * pa = (struct param *)v.sival_ptr;
printf("callback %c\n",pa->c);
}
int main(int argc,char ** argv)
{
restart:
cnt = 0;
timer_t timerid;
struct sigevent sev;
memset(&sev, 0, sizeof(struct sigevent));
p.i = 100;
p.c = 'c';
sev.sigev_notify = SIGEV_THREAD;
sev.sigev_notify_function = callback;
sev.sigev_value.sival_ptr = &p;
if(-1 == timer_create(CLOCK_REALTIME,&sev,&timerid)){
printf("timer_create fail");
}
struct itimerspec its;
its.it_value.tv_sec = 1;
its.it_value.tv_nsec = 0;
its.it_interval.tv_sec = 1;
its.it_interval.tv_nsec = 0;
if(-1==timer_settime(timerid, 0, &its, NULL)){
printf("timer_settime fail");
}
while(1)
{
sleep(10);
cnt++;
if(cnt == 2){ // 20秒后关闭定时器
timer_delete(timerid);
}
else if(cnt == 4){ // 40秒后重新创建定时器
goto restart;
}
}
}
alarm：
//功能描述：在5s内轮询产生的随机数(1s生产一个随机数)，判断随机数是不是100的整数倍，如果是，则输出定时器剩余时间，如果不是，继续
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <setjmp.h>
enum{
TIMER_HANDLER=1, //来自中断处理函数跳转点
};
#define SAVE_SIGMASK 1
long lrandom; //随机数
int remain; //剩余时间
void endup(void);
void do_clean(void);
void timer_handler(void);
jmp_buf sv_p1;
int main(int argc,char ** argv)
{
int interval=5;//多久中断超时一次
int iRet;
signal(SIGALRM,(void *)timer_handler);
//setjmp(sv_p1); //不使用
iRet = sigsetjmp(sv_p1,SAVE_SIGMASK);
if(iRet == TIMER_HANDLER)
{
//从中断处理函数跳过来的
printf("jump from void timer_handler(void)\n");
}
else
{
//从其他地方跳过来的
}
alarm(interval);//开始计时
while(1)
{
sleep(1);
lrandom=random();
int yushu;
yushu=lrandom%100;//求余数
printf("yushu = [%ld],lrandom = [%ld]\n",yushu,lrandom);
if(yushu==0)
{
//整除了
remain = alarm(0);//cancle counter,return remain seconds
printf("got a number which can be divided by 100 , %d seconds remaining,num is [%ld]\n",remain,lrandom);
alarm(interval); //重置定时器
}
}
}
void timer_handler(void)
{
printf("time out\n");
//1.end of process
//endup();
//2.jump to somewhere,goto 只能在当前栈内跳转，栈外跳转使用longjmp系列，
//这里使用siglongjmp和sigsetjmp，因为使用longjmp和setjmp在入中断处理函数后，
//会自动把中断掩码清0，这样可屏蔽中断就全都被关闭了，下次再满足中断条件也不会入中断了
printf("goto save point 1\n");
//longjmp(sv_p1,TIMER_HANDLER) //不使用
siglongjmp(sv_p1,TIMER_HANDLER);//TIMER_HANDLER为返回值，这个值作为sigsetjmp的返回值，用来判断跳转点
}
void endup(void)
{
do_clean();
exit(-1);
}
void do_clean(void)
{
}
原生定时器(saw timer)：
#include <linux/timer.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
static inline void Start_timer(struct timer_list *timer,unsigned long msec);
static inline void Init_timer(struct timer_list *timer,Handler routine,unsigned long argument);
static inline void Cancle_timer(struct timer_list *timer);
typedef void (*Handler) (void *);
struct timer_class{
struct timer_list identity;
char * desc;
unsigned long interval;
Handler routine;
}timer1;
int main (int argc,char ** argv)
{
timer1.desc="timer used for xxx\n";
timer1.interval=1000;
timer1.routine=(Handler)time_out_handler;
//1.INIT A TIMER
Init_timer(&(timer1.identity),timer1.routine,(unsigned long)timer1);
//2.START A TIMER
Start_timer(&(timer1.identity),timer1.interval);
//3.have a sleep
while(1) sleep(1);
}
void time_out_handler(struct timer_class *argu)
{
arug=(struct timer_calss *)argu;
//restart timer
Start_timer(argu->interval);
argu->interval *=2;
// printf("time out! timer set to %ld\n",argu->interval);
}
static inline void Start_timer(struct timer_list *timer,unsigned long msec)
{
mod_timer(timer,jiffies + msec_to_jiffies(msec) + 1);
}
static inline void Init_timer(struct timer_list *timer,Handler routine,unsigned long argument)
{
setup_timer(timer,routine,argument);
}
static inline void Cancle_timer(struct timer_list *timer)
{
del_timer_sync(timer);
}
