Date: Wed, 28 Jan 2004 12:01:27 -0500 (EST) From: Daniel Eischen <eischen@vigrid.com> To: Mike Makonnen <mtm@identd.net> Cc: Peter Kostouros <kpeter@melbpc.org.au> Subject: Re: pthread_mutex_trylock() should never block Message-ID: <Pine.GSO.4.10.10401281158460.7302-100000@pcnet5.pcnet.com> In-Reply-To: <20040128165031.GA3461@mobile.acsolutions.com>
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On Wed, 28 Jan 2004, Mike Makonnen wrote: > 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... Yes, but the implementation has to use internal locks to keep the mutex in a consistent state. There is no problem here. -- Dan Eischen
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