[vlc-commits] os2: implement vlc_once()

[KO Myung-Hun]

vlc | branch: master | KO Myung-Hun <komh78 at gmail.com> | Thu May 10 21:41:46 2018 +0900| [94756f160c776300c9f72290dbf5864fad9021d4] | committer: Thomas Guillem

os2: implement vlc_once()

Signed-off-by: Thomas Guillem <thomas at gllm.fr>

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=94756f160c776300c9f72290dbf5864fad9021d4
---

 include/vlc_threads.h |  6 ++++++
 src/os2/thread.c      | 28 ++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/include/vlc_threads.h b/include/vlc_threads.h
index 508ddbc001..b0891ac88c 100644
--- a/include/vlc_threads.h
+++ b/include/vlc_threads.h
@@ -125,6 +125,12 @@ typedef struct
 #define VLC_STATIC_COND { NULLHANDLE, 0, NULLHANDLE, 0 }
 #define LIBVLC_NEED_SEMAPHORE
 #define LIBVLC_NEED_RWLOCK
+typedef struct
+{
+    unsigned done;
+    vlc_mutex_t mutex;
+} vlc_once_t;
+#define VLC_STATIC_ONCE { 0, VLC_STATIC_MUTEX }
 typedef struct vlc_threadvar *vlc_threadvar_t;
 typedef struct vlc_timer *vlc_timer_t;
 
diff --git a/src/os2/thread.c b/src/os2/thread.c
index 42dba0aa10..e4afb5bbe2 100644
--- a/src/os2/thread.c
+++ b/src/os2/thread.c
@@ -429,6 +429,34 @@ int vlc_cond_timedwait_daytime (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
     return vlc_cond_wait_common (p_condvar, p_mutex, ulTimeout);
 }
 
+void vlc_once(vlc_once_t *once, void (*cb)(void))
+{
+    unsigned done;
+
+    /* load once->done */
+    __atomic_xchg( &done, once->done );
+
+    /* not initialized ? */
+    if( done == 0 )
+    {
+        vlc_mutex_lock( &once->mutex );
+
+        /* load once->done */
+        __atomic_xchg( &done, once->done );
+
+        /* still not initialized ? */
+        if( done == 0 )
+        {
+            cb();
+
+            /* set once->done to 1 */
+            __atomic_xchg( &once->done, 1 );
+        }
+
+        vlc_mutex_unlock( &once->mutex );
+    }
+}
+
 /*** Thread-specific variables (TLS) ***/
 struct vlc_threadvar
 {