L17-L21：将感兴趣的信号加入到sigset_t中；
L24：调用signalfd，把信号集与fd关联起来，第一个参数为-1表示新建一个signalfd，不是-1并且是一个合法的signalfd表示向其添加新的信号。
L29：阻塞等待信号的发生并读取。根据读取的结果可以知道发生了什么信号。
timerfd涉及的API
#include <sys/timerfd.h>
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, struct itimerspec *curr_value);
#include <sys/timerfd.h>
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, struct itimerspec *curr_value);
timerfd_create：创建一个timerfd；返回的fd可以进行如下操作：read、select(poll、epoll)、close
timerfd_settime：设置timer的周期，以及起始间隔
timerfd_gettime：获取到期时间。
//函数参数中数据结构如下：
struct timespec
{
time_t tv_sec; /* Seconds */
long tv_nsec; /* Nanoseconds */
};
struct itimerspec
{
struct timespec it_interval; /* Interval for periodic timer */
struct timespec it_value; /* Initial expiration */
};
//函数参数中数据结构如下：
struct timespec
{
time_t tv_sec; /* Seconds */
long tv_nsec; /* Nanoseconds */
};
struct itimerspec
{
struct timespec it_interval; /* Interval for periodic timer */
struct timespec it_value; /* Initial expiration */
};
l例子
#include <sys/timerfd.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h> /* Definition of uint64_t */
#define handle_error(msg)
do { perror(msg); exit(EXIT_FAILURE); } while (0)
void printTime()
{
struct timeval tv;
gettimeofday(&tv, NULL);
printf("printTime: current time:%ld.%ld ", 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 + atoi(argv[1]);
new_value.it_value.tv_nsec = now.tv_nsec;
new_value.it_interval.tv_sec = atoi(argv[2]);
new_value.it_interval.tv_nsec = 0;
int fd = timerfd_create(CLOCK_REALTIME, 0);
if (fd == -1)
handle_error("timerfd_create");
if (timerfd_settime(fd, TFD_TIMER_ABSTIME, &new_value, NULL) == -1)
handle_error("timerfd_settime");
printTime();
printf("timer startedn");
for (uint64_t tot_exp = 0; tot_exp < atoi(argv[3]);)
{
uint64_t exp;
ssize_t s = read(fd, &exp, sizeof(uint64_t));
if (s != sizeof(uint64_t))
handle_error("read");
tot_exp += exp;
printTime();
printf("read: %llu; total=%llun",exp, tot_exp);
}
exit(EXIT_SUCCESS);
}
#include <sys/timerfd.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h> /* Definition of uint64_t */
#define handle_error(msg)
do { perror(msg); exit(EXIT_FAILURE); } while (0)
void printTime()
{
struct timeval tv;
gettimeofday(&tv, NULL);
printf("printTime: current time:%ld.%ld ", 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 + atoi(argv[1]);
new_value.it_value.tv_nsec = now.tv_nsec;
new_value.it_interval.tv_sec = atoi(argv[2]);
new_value.it_interval.tv_nsec = 0;
int fd = timerfd_create(CLOCK_REALTIME, 0);
if (fd == -1)
handle_error("timerfd_create");
if (timerfd_settime(fd, TFD_TIMER_ABSTIME, &new_value, NULL) == -1)
handle_error("timerfd_settime");
printTime();
printf("timer startedn");
for (uint64_t tot_exp = 0; tot_exp < atoi(argv[3]);)
{
uint64_t exp;
ssize_t s = read(fd, &exp, sizeof(uint64_t));
if (s != sizeof(uint64_t))
handle_error("read");
tot_exp += exp;
printTime();
printf("read: %llu; total=%llun",exp, tot_exp);
}
exit(EXIT_SUCCESS);
}
