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authorLennart Poettering <lennart@poettering.net>2006-09-09 23:54:19 +0000
committerLennart Poettering <lennart@poettering.net>2006-09-09 23:54:19 +0000
commitd0dcde060bb3e5fd04512d16afdd1ed71e780e08 (patch)
tree04008a17ded84a5c21664f76b0689cce74a95879 /src/pulsecore
parent6d532029eaac08a3b60a28752f23f0586f895168 (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')
-rw-r--r--src/pulsecore/once-posix.c69
-rw-r--r--src/pulsecore/once.h14
2 files changed, 74 insertions, 9 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. */
+}
diff --git a/src/pulsecore/once.h b/src/pulsecore/once.h
index a82a3c86..0aabb3f2 100644
--- a/src/pulsecore/once.h
+++ b/src/pulsecore/once.h
@@ -22,21 +22,17 @@
USA.
***/
-#include <pulsecore/atomic.h>
+#include <pulsecore/mutex.h>
typedef struct pa_once {
- pa_atomic_int_t atomic;
+ unsigned int once_value;
+ pa_mutex *mutex;
} pa_once_t;
-#define PA_ONCE_INIT { PA_ATOMIC_INIT(0) }
-
-#define pa_once_test(o) (pa_atomic_cmpxchg(&(o)->atomic, 0, 1))
+#define PA_ONCE_INIT { .once_value = 0, .mutex = NULL }
typedef void (*pa_once_func_t) (void);
-static inline void pa_once(pa_once_t *o, pa_once_func_t f) {
- if (pa_once_test(o))
- f();
-}
+void pa_once(pa_once_t *o, pa_once_func_t f);
#endif