文章目录定时器说明举例定时器说明•函数功能通过文件I/O方式去获取定时器的通知事件•相关API–int timerfd_create(int clockid, int flags);–int timerfd_settime(int fd, int flags, const struct itimerspec *new_value,struct itimerspec *old_value);–int timerfd_gettime(int fd, sturct itimerspec *curr_value);举例#include stdio.h #include stdlib.h #include unistd.h #include stdint.h #include time.h #include sys/time.h #include sys/timerfd.h #define handle_error(msg) \ do{perror(msg);exit(EXIT_FAILURE);}while(0) void print_time () { struct timeval tv; gettimeofday (tv, NULL); printf (current time: %ld.%ld\n, tv.tv_sec, tv.tv_usec); } int main (int argc, char *argv[]) { struct timespec now; if (clock_gettime (CLOCK_REALTIME, now) -1) handle_error (clock_gettime); struct itimerspec new_value; new_value.it_value.tv_sec now.tv_sec 10; // 10s later,timer will timeout new_value.it_value.tv_nsec now.tv_nsec; new_value.it_interval.tv_sec 3; //timer intelval new_value.it_interval.tv_nsec 0; int fd timerfd_create (CLOCK_REALTIME, 0); if (fd -1) handle_error (timerfd_creat); if (timerfd_settime(fd, TFD_TIMER_ABSTIME, new_value, NULL) -1) handle_error (timerfd_settime); print_time (); printf (timer started\n); for (uint64_t tot_exp 0; tot_exp 20;) //timer run times: 20 { uint64_t exp; ssize_t s read (fd, exp, sizeof(uint64_t)); if (s ! sizeof(uint64_t)) handle_error (read); tot_exp exp; print_time (); printf (read: %llu, total: %llu\n, exp, tot_exp); } return 0; }
