add support for static mutexes

src/pulsecore/mutex-posix.c

@@ -138,3 +138,23 @@ int pa_cond_wait(pa_cond *c, pa_mutex *m) {
 
     return pthread_cond_wait(&c->cond, &m->mutex);
 }
+
+pa_mutex* pa_static_mutex_get(pa_static_mutex *s, pa_bool_t recursive, pa_bool_t inherit_priority) {
+    pa_mutex *m;
+
+    pa_assert(s);
+
+    /* First, check if already initialized and short cut */
+    if ((m = pa_atomic_ptr_load(&s->ptr)))
+        return m;
+
+    /* OK, not initialized, so let's allocate, and fill in */
+    m = pa_mutex_new(recursive, inherit_priority);
+    if ((pa_atomic_ptr_cmpxchg(&s->ptr, NULL, m)))
+        return m;
+
+    /* Him, filling in failed, so someone else must have filled in
+     * already */
+    pa_assert_se(m = pa_atomic_ptr_load(&s->ptr));
+    return m;
+}

src/pulsecore/mutex.h

@@ -23,6 +23,7 @@
 ***/
 
 #include <pulsecore/macro.h>
+#include <pulsecore/atomic.h>
 
 typedef struct pa_mutex pa_mutex;
 
@@ -45,4 +46,10 @@ void pa_cond_free(pa_cond *c);
 void pa_cond_signal(pa_cond *c, int broadcast);
 int pa_cond_wait(pa_cond *c, pa_mutex *m);
 
+typedef struct pa_static_mutex {
+    pa_atomic_ptr_t ptr;
+} pa_static_mutex;
+
+pa_mutex* pa_static_mutex_get(pa_static_mutex *m, pa_bool_t recursive, pa_bool_t inherit_priority);
+
 #endif