CLOCK_MONOTONIC和pthread_mutex_timedlock /那么pthread_cond_timedwait [英] CLOCK_MONOTONIC and pthread_mutex_timedlock / pthread_cond_timedwait

问题描述

的<一个href=\"http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_timedlock.html\">pthread_mutex_timedlock文档说， abs_timeout 需要 CLOCK_REALTIME 。然而，我们都知道这是不恰当的定时特定的时间（由于系统时间调整）。

The pthread_mutex_timedlock documentation says that abs_timeout takes a CLOCK_REALTIME. However, we all know that it is inappropriate for timing a specific duration (due to system time adjustments).

有没有一种方法，使对 CLOCK_MONOTONIC 是便携式pthread的锁超时？同样的问题也有那么pthread_cond_timedwait。

Is there a way to make pthread lock timeout on CLOCK_MONOTONIC that is portable? The same goes with pthread_cond_timedwait.

推荐答案

说完看了看文件和 pthreads.h中，我不能找到一种方法，使<一个href=\"http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_timedlock.html\">pthread_mutex_timedlock使用 CLOCK_MONOTONIC ，所以我认为这不是（目前）成为可能。对于<一个href=\"http://pubs.opengroup.org/onlinepubs/009604599/functions/pthread_cond_wait.html\">pthread_cond_timedwait,但是，您可以用code是这样的：

Having looked at the documentation and pthread.h, I can't find a way to make pthread_mutex_timedlock use CLOCK_MONOTONIC so I assume that's not (currently) possible. For pthread_cond_timedwait, however, you can use code like this:

pthread_condattr_t attr;
pthread_cond_t cond;
/* ... */
pthread_condattr_init(&attr);
pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
pthread_cond_init(&cond, &attr);

我省略了错误code检查清楚，但当然你应该做的。

I've omitted error code checking for clarity, but of course you should do that.

我认为 CLOCK_REALTIME 的使用，因为它总是可用的，而在原则上 CLOCK_MONOTONIC 是可选的。另外，我不知道是否设置绝对超时后，使系统调用得到由信号等中断，更容易恢复。

I assume that CLOCK_REALTIME is used because it's always available whereas in principle CLOCK_MONOTONIC is optional. Also, I wonder if setting absolute timeouts makes it easier to recover after system calls get interrupted by signals and the like.

不过，它似乎颇不一致，该时钟可以在某些情况下设置，而不是别人 - 有真应了 pthread_mutexattr_setclock（），但很可惜有没有似乎是一个。我猜你只希望有人不设置时钟！

However, it does seem quite inconsistent that the clock can be set in some cases and not others - there really should be a pthread_mutexattr_setclock(), but alas there does not seem to be one. I guess you'll just have to hope someone doesn't set the clock!

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