site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com Thread-index: AcZwc3Qjsm5DQbBARYaBkXg3a2f2NwABPsAw Thread-topic: question for CFRunLoopStop() Thanks for your reply. Perhaps I am missing something, but removing/invalidating the timer from the child runloop does not always provoke the child thread to exit. So after having read your reply, I suppose that the best way to solve my problem would be to stop the runloop. But the documentation says that removing all sources from a runloop causes CFRunLoopRun() to return: "The current thread's run loop runs in the default mode (see "Default Run Loop Mode") until the run loop is stopped with CFRunLoopStop or all the sources and timers are removed from the default run loop mode." However, I do not consistently find that this is true in my case. Perhaps there is a fault in my code, but invalidating the timer does not always cause the child thread to exit (and according to the docs, invalidating a timer removes it from the runloop). However, so far CFRunLoopStop() consistently works. Offhand could you explain this? Finally, I was using pthread_join as a precautionary measure only, that is just to make sure that after the child had been ordered to quit, that it had fully exited (and then I could clean up its resources). thanks for your reply, Philip Lukidis -----Original Message----- From: Kevin Van Vechten [mailto:kevin@opendarwin.org] Sent: Friday, May 05, 2006 2:33 PM To: Philip Lukidis Cc: darwin-dev@lists.apple.com Subject: Re: question for CFRunLoopStop() On May 5, 2006, at 8:46 AM, Philip Lukidis wrote:

Hello. I hope that I'm posting this to the correct list.

Yep.

Concerning CF, I was wondering if the following scenario is correct: A "parent" thread creates a child thread via the pthread library. The child thread has only 1 runloop source on it (a timer in fact), and once the timer is applied onto the child runloop by the child itself, the child proceeds to call CFRunLoopRun() on itself. Now the parent is responsible for running down this child on demand. Can the parent rundown the child by:

I'm not sure what you mean by "rundown," but I'll assume you mean stop the child's runloop.

-invalidating the timer (via CFRunLoopTimerInvalidate()) -removing the timer (via CFRunLoopRemoveTimer())

It's my understanding that a RunLoop will stop running when it has no more valid sources or timers to listen to. So if there is only one timer in the run loop, either of these would accomplish your goal.

-calling CFRunLoopIsWaiting() in a while loop until it returns true (which indicates that all callbacks have drained and that it is waiting again, but of course since the timer was invalidated it can never be called again). Of course I should NOT holding a resource which the callback might need in order to execute and exit.

While I'm sure you could make something like this work, it's pretty contrived.

-calling CFRunLoopStop()

Yes, this will stop the run loop (even if it still has valid sources).

-calling pthread_join() on the pthread

I don't think this will stop the run loop. Instead, it will block the parent thread until the child thread exits.

Can this also be extended to other runloop sources, by using CFRunLoopSourceInvalidate() instead of CFRunLoopTimerInvalidate(), and CFRunLoopRemoveSource() instead of CFRunLoopRemoveTimer()?

For sources that are of type CFRunLoopSourceRef, yes.

If these procedures are incorrect, why so, and what are the alternatives?

I don't see any of the above as "alternatives." In your case, with only one runloop source, CFRunLoopTimerInvalidate(), CFRunLoopRemoveTimer(), and CFRunLoopStop() all have the same end- result. However, this is a consequence of a simple example, and not generally true. Invalidating and removing a source have different semantics. For example, you may want to invalidate a source (no matter how many runloops may be using it), or alternatively you may want to remove a source from a particular runloop but keep it as a source in another runloop (or perhaps add it back to the same runloop at a later time). Stopping a runloop doesn't affect any of the sources, so it can be restarted at a later time in the same configuration that it was in originally. - Kevin _______________________________________________ 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... This email sent to site_archiver@lists.apple.com