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Date:      Wed, 28 Jan 2004 19:50:32 +0300
From:      Mike Makonnen <mtm@identd.net>
To:        Daniel Eischen <eischen@vigrid.com>
Cc:        Peter Kostouros <kpeter@melbpc.org.au>
Subject:   Re: pthread_mutex_trylock() should never block
Message-ID:  <20040128165031.GA3461@mobile.acsolutions.com>
In-Reply-To: <Pine.GSO.4.10.10312070112090.22843-100000@pcnet5.pcnet.com>
References:  <3FD245FF.3040003@melbpc.org.au> <Pine.GSO.4.10.10312070112090.22843-100000@pcnet5.pcnet.com>

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On Sun, Dec 07, 2003 at 01:34:31AM -0500, Daniel Eischen wrote:
> 
> The man page may not mention it, and that may be a bug, but I
> think a pthread_mutex_trylock() on a non-recursive mutex is allowed
> to return EDEADLK.
> 
>   http://www.opengroup.org/onlinepubs/007904975/functions/pthread_mutex_trylock.html
> 
>   If the mutex type is PTHREAD_MUTEX_ERRORCHECK, then error
>   checking shall be provided. If a thread attempts to relock a
>   mutex that it has already locked, an error shall be returned.
>   If a thread attempts to unlock a mutex that it has not locked
>   or a mutex which is unlocked, an error shall be returned.
> 
>   ...

If you look further down in the spec you will see:

   The pthread_mutex_trylock() function shall be equivalent to
   pthread_mutex_lock(), except that if the mutex object referenced
   by mutex is currently locked (by any thread, including
   the current thread), the call shall return immediately...

Cheers.
-- 
Mike Makonnen  | GPG-KEY: http://www.identd.net/~mtm/mtm.asc
mtm@identd.net | Fingerprint: 00E8 61BC 0D75 7FFB E4D3  6BF1 B239 D010 3215 D418
mtm@FreeBSD.Org| FreeBSD - Unleash the Daemon !



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