[FFmpeg-devel] [PATCH] avcodec/utils: use a default lock manager that uses a spinlock

[Michael Niedermayer]

That makes avformat & avcodec thread safe without the need to explicitly
register a lock manager.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
---
 libavcodec/utils.c |   26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 3832b81..cf7be5e 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -56,9 +56,33 @@
 # include <iconv.h>
 #endif
 
+static int default_lockmgr_cb(void **mutex, enum AVLockOp op)
+{
+    void * volatile *state = mutex;
+
+    switch (op) {
+    case AV_LOCK_CREATE:
+        *state = NULL;
+        return 0;
+    case AV_LOCK_OBTAIN:
+        while (avpriv_atomic_ptr_cas(state, NULL, mutex))
+            ;
+
+        return 0;
+    case AV_LOCK_RELEASE:
+         if (avpriv_atomic_ptr_cas(state, mutex, NULL) != mutex)
+             av_assert0(0);
+
+        return 0;
+    case AV_LOCK_DESTROY:
+        return 0;
+    }
+    return 1;
+}
+
 volatile int ff_avcodec_locked;
 static int volatile entangled_thread_counter = 0;
-static int (*lockmgr_cb)(void **mutex, enum AVLockOp op);
+static int (*lockmgr_cb)(void **mutex, enum AVLockOp op) = default_lockmgr_cb;
 static void *codec_mutex;
 static void *avformat_mutex;
 
-- 
1.7.9.5