setitimer函数测试代码1

/*thread1先获取系统时间，然后阻塞，紧接着thread2调用setitimer开启定时器，定时10ms，时间到后收到信号SIGALRM，转到信号处理函数change_semaphore改变信号量，信号量变为1以后thread1停止阻塞，输出两次时间差*/

#include<stdio.h>
#include<stdlib.h>
#include<sys/time.h>
#include<pthread.h>
#include<time.h>
#include<signal.h>
#include<unistd.h>
#include<semaphore.h>

void change_semaphore();

struct sem_t
{
long int sem1;
};
struct sem_t sem; // define a struct of semaphore

struct itimerval timer1; //define a struct which will be used by function setitimer

void thread1()
{
long int time;
struct timeval time_start;
struct timeval time_end;
gettimeofday((struct timeval*)&time_start,NULL); //get start time and save it to struct
sem_wait(&sem); //block the present thread till semaphore is bigger than zero
gettimeofday((struct timeval*)&time_end,NULL); //get end time and save it to struct
time=time_end.tv_usec-time_start.tv_usec; //calculate the running time of timer
if(time>20000)
{
printf("the running time of timer is %d us\n",time);
}
exit(0);
}

void thread2()
{
setitimer(ITIMER_REAL,&timer1,NULL); //turn on timer
signal(SIGALRM,change_semaphore); //register signal SIGALRM to function change_semaphore
pause();//waiting for signal SIGALRM
exit(0);
}

void change_semaphore()
{
sem_post(&sem); //semaphore adds one
}

int main()
{
pthread_t id1,id2;
int ret1,ret2;
timer1.it_value.tv_usec=10000; //initialize timer
sem_init(&sem,0,0); //initialize semaphore
ret1=pthread_create(&id1,NULL,(void*)thread1,NULL); //create thread 1
ret2=pthread_create(&id2,NULL,(void*)thread2,NULL); //create thread 2
pthread_join(id1,NULL); //waiting for thread 1 to finish
pthread_join(id2,NULL); //waiting for thread 2 to finish
return 0;
}

# shell程序

#!/bin/bash
for ((i=0;i<10000;i++));
do
/root/program/setitimer_test2;
done
#this shell program is used for executing setitimer_test2 for 10000 times