Question

有人可以帮助我将我的代码转换为有效的代码：

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

/* call back function - inform the user the time has expired */
void timeout_call_back()
{
    printf("=== your time is up ===\n");
    // doing some other stuff
}

/* Go to sleep for a period of seconds */
static void* start_timer(void *args)
{
    /* function pointer */
    void (*finish_function)();


    int seconds = *((int*) args);
    pthread_mutex_lock(&mutex); // I want to do this action atomically
    printf("thread ID : %ld, go to sleep for %d\n", pthread_self(), seconds);

    finish_function = timeout_call_back;

    // ATOMIC PART
    // This function is called in real time, so I need it
    // to be safe, and it's executed just when the timer is not reached.
    atomic_function_callback();

    // THIS IS MY PROBLEM. I WANT TO WAIT for (seconds) seconds,
    // but I don't want to block other threads.
    sleep(seconds); 

    /* call the cb to inform the user time is out */
    (*finish_function)();
    pthread_mutex_unlock(&mutex);

    pthread_exit(NULL);
}

int main()
{
    pthread_t thread1, thread2, thread3;
    int seconds1 = 300;
    int seconds2 = 600;
    int seconds3 = 900;

    int rc1, rc2, rc3;

    rc1 =  pthread_create(&thread1, NULL, start_timer, (void *) &seconds1);
    if(rc1)
    printf("=== Failed to create thread1\n");
    rc2 =  pthread_create(&thread2, NULL, start_timer, (void *) &seconds2);
    if(rc2)
    printf("=== Failed to create thread2\n");

    rc3 =  pthread_create(&thread3, NULL, start_timer, (void *) &seconds3);
    if(rc3)
    printf("=== Failed to create thread3\n");

    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL);
    pthread_join(thread3, NULL);

    printf("=== End of all threads in ===\n");

    return 0;
}

当我运行此代码时，一个线程可以在一段时间内运行（导致互斥）但我需要这个互斥锁。 sleep（）有什么替代方法可以让我做一个非阻塞计时器吗？

这只是一个样本，我的真实计时器很长（8小时）。

感谢。

Answer 1

检查条件变量。 https://computing.llnl.gov/tutorials/pthreads/#ConditionVariables

您要做的是设置条件变量并设置睡眠的定时等待。当您调用定时等待时，将为其他线程释放互斥锁。当条件变量唤醒时，您将检查您的计时器是否已经过去并通知您的回叫finish_function。

Answer 2

您的问题有点模糊，但我认为您希望所有三个线程同时处于休眠状态，但是使用互斥锁来确保它们不会同时运行finish函数？

如果是这种情况，那么您只想使用互斥锁来保护finish_function的调用，而不是保护睡眠。然后每个线程将彼此休息，并且随着时间的推移，互斥锁将确保一次只有一个线程调用finish_function。

Answer 3

查看pthread_cond_timedwait

c中的线程计时器

3 个答案: