Mark shared variables as volatile

'n_waiting' and 'n_waiting_for_accept' may be accessed from mulitple
threads, and thus need to be marked as volatile to suppres certain
compiler optimisations. All uses are protected by a mutex, so we don't
need to worry about cache issues (added documentation for this as well).

This addresses bug #738.

diff --git a/src/pulse/thread-mainloop.c b/src/pulse/thread-mainloop.c
index a2b98ce..14ed926 100644 (file)
--- a/src/pulse/thread-mainloop.c
+++ b/src/pulse/thread-mainloop.c
@@ -51,7 +51,7 @@
 
 struct pa_threaded_mainloop {
     pa_mainloop *real_mainloop;
-    int n_waiting, n_waiting_for_accept;
+    volatile int n_waiting, n_waiting_for_accept;
 
     pa_thread* thread;
     pa_mutex* mutex;
@@ -185,6 +185,7 @@ void pa_threaded_mainloop_unlock(pa_threaded_mainloop *m) {
     pa_mutex_unlock(m->mutex);
 }
 
+/* Called with the lock taken */
 void pa_threaded_mainloop_signal(pa_threaded_mainloop *m, int wait_for_accept) {
     pa_assert(m);
 
@@ -198,6 +199,7 @@ void pa_threaded_mainloop_signal(pa_threaded_mainloop *m, int wait_for_accept) {
     }
 }
 
+/* Called with the lock taken */
 void pa_threaded_mainloop_wait(pa_threaded_mainloop *m) {
     pa_assert(m);
 
@@ -212,6 +214,7 @@ void pa_threaded_mainloop_wait(pa_threaded_mainloop *m) {
     m->n_waiting --;
 }
 
+/* Called with the lock taken */
 void pa_threaded_mainloop_accept(pa_threaded_mainloop *m) {
     pa_assert(m);