site_archiver@lists.apple.com Delivered-To: Darwin-dev@lists.apple.com Le 5 janv. 06 à 13:54, philippe wicker a écrit : On Jan 5, 2006, at 12:25 PM, Stéphane Letz wrote: Hi, pthread_mutex_lock(mutex); int status; while (1) { status = pthread_cond_timedwait(cond, mutex, absolute_time); if (status == EINVAL) break; // ERROR: some invalid parameters if (status == ETIMEDOUT) break; // OK, the actual time-out } pthread_mutex_unlock(mutex); // Check the status and do the timer thread job Thanks Stephane Letz Hi Philippe, Stephane _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... We need to setup a 1 millisecond periodic timer used in a real- time (time constraint) thread in a pure C console program. We first tried to use the carbon Timer manager API (with NewTimerUPP and a timeManagerTask ...) but without being able to access the thread that call the timer task in order to setup its scheduling property to be "time constraint". We try also low-level function like mach_wait_until but had problems on Panther. What is the recommended way (API...) to implement a timer? Dunno if this is the recommended API but I would do it using the POSIX API pthread_cond_timedwait (or alternatively pthread_cond_timedwait_relative_np). Create your timer thread with pthread_create, and call mach specific API to set the "time constraint" scheduling policy. You could also use CoreAudio SDK utilities CAPThread, CAMutex and CAGuard which are nice C++ encapsulations of POSIX thread, mutex and variable condition concepts that allow you to do the same things in a simpler way. "pthread_cond_timedwait" requires a mutex and a condvar. In your case you'll use only the "time out" part of the API but you still need to pass valid mutex and cond although the mutex will never be signaled. Just in case, be aware that "pthread_cond_timedwait" can spuriously return with a "no error (0)" status. To manage this situation enclose the "pthread_cond_timedwait" call within a loop such as: It may not be necessary in your case to lock the mutex but I don't know if the OS will correctly deal with that. It expects a locked mutex at entry, unlocks it to put the caller thread to sleep and relocks it when the thread has to wake up. Thanks for the info, actually I was wondering if a higher-level API was available because I would prefer not having to use function that "wait until a specified date". The thing is that when using this kind of functions, i have to deal with cases where an abnormal latency occur in the system, then the wait function returns too late, I have to compensate for that for the next interrupt and so on. If I use a CoreAudio task as a way to schedule my 1 millisecond interrupt, the nice thing is that CoreAudio seems to automically ajust/compensate timing deviations. I can have a serie of call that on average is 1000us. I would like to have timer API that allows to setup the same thing. This email sent to site_archiver@lists.apple.com