Use a separate backend callback to start playback of the device

This allows us to properly update the ALCdevice and its resources with the new
parameters before starting playback, instead of expecting the mixer to block
and wait after it has begun.

This also lets us avoid holding the device lock while resetting and starting
the device, which helps prevent lock inversion on some backends (ie, one thread
locking A then B, and another thread locking B then A), ultimately allowing
certain backends to asynchronously update the ALCdevice without risk of lockup.
Capture still has issues here, however.

1 files changed, 30 insertions, 10 deletions

diff --git a/Alc/backends/opensl.c b/Alc/backends/opensl.c
index 58acc828..5ff60276 100644
--- a/Alc/backends/opensl.c
+++ b/Alc/backends/opensl.c
@@ -242,6 +242,10 @@ static void opensl_close_playback(ALCdevice *Device)
 {
     osl_data *data = Device->ExtraData;
 
+    if(data->bufferQueueObject != NULL)
+        SLObjectItf_Destroy(data->bufferQueueObject);
+    data->bufferQueueObject = NULL;
+
     SLObjectItf_Destroy(data->outputMix);
     data->outputMix = NULL;
 
@@ -257,16 +261,13 @@ static ALCboolean opensl_reset_playback(ALCdevice *Device)
 {
     osl_data *data = Device->ExtraData;
     SLDataLocator_AndroidSimpleBufferQueue loc_bufq;
-    SLAndroidSimpleBufferQueueItf bufferQueue;
     SLDataLocator_OutputMix loc_outmix;
     SLDataFormat_PCM format_pcm;
     SLDataSource audioSrc;
     SLDataSink audioSnk;
-    SLPlayItf player;
     SLInterfaceID id;
     SLboolean req;
     SLresult result;
-    ALuint i;
 
 
     Device->UpdateSize = (ALuint64)Device->UpdateSize * 44100 / Device->Frequency;
@@ -303,6 +304,10 @@ static ALCboolean opensl_reset_playback(ALCdevice *Device)
     audioSnk.pFormat = NULL;
 
 
+    if(data->bufferQueueObject != NULL)
+        SLObjectItf_Destroy(data->bufferQueueObject);
+    data->bufferQueueObject = NULL;
+
     result = SLEngineItf_CreateAudioPlayer(data->engine, &data->bufferQueueObject, &audioSrc, &audioSnk, 1, &id, &req);
     PRINTERR(result, "engine->CreateAudioPlayer");
     if(SL_RESULT_SUCCESS == result)
@@ -310,11 +315,29 @@ static ALCboolean opensl_reset_playback(ALCdevice *Device)
         result = SLObjectItf_Realize(data->bufferQueueObject, SL_BOOLEAN_FALSE);
         PRINTERR(result, "bufferQueue->Realize");
     }
-    if(SL_RESULT_SUCCESS == result)
+
+    if(SL_RESULT_SUCCESS != result)
     {
-        result = SLObjectItf_GetInterface(data->bufferQueueObject, SL_IID_BUFFERQUEUE, &bufferQueue);
-        PRINTERR(result, "bufferQueue->GetInterface");
+        if(data->bufferQueueObject != NULL)
+            SLObjectItf_Destroy(data->bufferQueueObject);
+        data->bufferQueueObject = NULL;
+
+        return ALC_FALSE;
     }
+
+    return ALC_TRUE;
+}
+
+static ALCboolean opensl_start_playback(ALCdevice *Device)
+{
+    osl_data *data = Device->ExtraData;
+    SLAndroidSimpleBufferQueueItf bufferQueue;
+    SLPlayItf player;
+    SLresult result;
+    ALuint i;
+
+    result = SLObjectItf_GetInterface(data->bufferQueueObject, SL_IID_BUFFERQUEUE, &bufferQueue);
+    PRINTERR(result, "bufferQueue->GetInterface");
     if(SL_RESULT_SUCCESS == result)
     {
         result = (*bufferQueue)->RegisterCallback(bufferQueue, opensl_callback, Device);
@@ -372,10 +395,6 @@ static void opensl_stop_playback(ALCdevice *Device)
 {
     osl_data *data = Device->ExtraData;
 
-    if(data->bufferQueueObject != NULL)
-        SLObjectItf_Destroy(data->bufferQueueObject);
-    data->bufferQueueObject = NULL;
-
     free(data->buffer);
     data->buffer = NULL;
     data->bufferSize = 0;
@@ -386,6 +405,7 @@ static const BackendFuncs opensl_funcs = {
     opensl_open_playback,
     opensl_close_playback,
     opensl_reset_playback,
+    opensl_start_playback,
     opensl_stop_playback,
     NULL,
     NULL,