diff options
author | Lennart Poettering <lennart@poettering.net> | 2006-09-09 23:54:19 +0000 |
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committer | Lennart Poettering <lennart@poettering.net> | 2006-09-09 23:54:19 +0000 |
commit | d0dcde060bb3e5fd04512d16afdd1ed71e780e08 (patch) | |
tree | 04008a17ded84a5c21664f76b0689cce74a95879 /src/pulsecore/once-posix.c | |
parent | 6d532029eaac08a3b60a28752f23f0586f895168 (diff) |
rework pa_once once again, because the once function needs to have terminated before pa_once returns, regardless whether the local call executes it or another thread does.
With the previous code it might happen that an long-running initializing in a once function is not terminated yet when another thread thinks it already is.
git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1387 fefdeb5f-60dc-0310-8127-8f9354f1896f
Diffstat (limited to 'src/pulsecore/once-posix.c')
-rw-r--r-- | src/pulsecore/once-posix.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/src/pulsecore/once-posix.c b/src/pulsecore/once-posix.c new file mode 100644 index 00000000..865997df --- /dev/null +++ b/src/pulsecore/once-posix.c @@ -0,0 +1,69 @@ +/* $Id$ */ + +/*** + This file is part of PulseAudio. + + PulseAudio is free software; you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as published + by the Free Software Foundation; either version 2 of the License, + or (at your option) any later version. + + PulseAudio is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with PulseAudio; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 + USA. +***/ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include <pthread.h> +#include <assert.h> + +#include <pulsecore/mutex.h> + +#include "once.h" + +#define ASSERT_SUCCESS(x) do { \ + int _r = (x); \ + assert(_r == 0); \ +} while(0) + +static pa_mutex *global_mutex; +static pthread_once_t global_mutex_once = PTHREAD_ONCE_INIT; + +static void global_mutex_once_func(void) { + global_mutex = pa_mutex_new(0); +} + +void pa_once(pa_once_t *control, pa_once_func_t func) { + assert(control); + assert(func); + + /* Create the global mutex */ + ASSERT_SUCCESS(pthread_once(&global_mutex_once, global_mutex_once_func)); + + /* Create the local mutex */ + pa_mutex_lock(global_mutex); + if (!control->mutex) + control->mutex = pa_mutex_new(1); + pa_mutex_unlock(global_mutex); + + /* Execute function */ + pa_mutex_lock(control->mutex); + if (!control->once_value) { + control->once_value = 1; + func(); + } + pa_mutex_unlock(control->mutex); + + /* Caveat: We have to make sure that the once func has completed + * before returning, even if the once func is not actually + * executed by us. Hence the awkward locking. */ +} |