Avoid locking the mixer when unqueueing buffers

1 files changed, 16 insertions, 4 deletions

diff --git a/OpenAL32/alSource.c b/OpenAL32/alSource.c
index d707f226..f0fb374f 100644
--- a/OpenAL32/alSource.c
+++ b/OpenAL32/alSource.c
@@ -33,6 +33,8 @@
 #include "alThunk.h"
 #include "alAuxEffectSlot.h"
 
+#include "threads.h"
+
 
 enum Resampler DefaultResampler = LinearResampler;
 const ALsizei ResamplerPadding[ResamplerMax] = {
@@ -2223,10 +2225,20 @@ AL_API ALvoid AL_APIENTRY alSourceUnqueueBuffers(ALuint src, ALsizei nb, ALuint
     OldHead = ExchangePtr((XchgPtr*)&source->queue, BufferList);
     if(BufferList)
     {
-        LockContext(context);
-        BufferList->prev->next = NULL;
-        BufferList->prev = NULL;
-        UnlockContext(context);
+        ALCdevice *device = context->Device;
+        RefCount count;
+
+        /* Cut the new head's link back to the old body. The mixer is robust
+         * enough to handle the link back going away. Once the active mix (if
+         * any) is complete, it's safe to finish cutting the old tail from the
+         * new head. */
+        BufferList = ExchangePtr((XchgPtr*)&BufferList->prev, NULL);
+        if(((count=device->MixCount)&1) != 0)
+        {
+            while(count == device->MixCount)
+                althrd_yield();
+        }
+        BufferList->next = NULL;
     }
     WriteUnlock(&source->queue_lock);