# HG changeset patch
# User Michael Pavone <pavone@retrodev.com>
# Date 1602464508 25200
# Node ID 66f08024d9e983b66cb92fee56a08b73c5a4caa9
# Parent  4c418ee9a9d80c634c18e42d414f6f152c6354cb
Fix occasional deadlock on startup when using audio sync

diff -r 4c418ee9a9d8 -r 66f08024d9e9 render_sdl.c
--- a/render_sdl.c	Sun Jul 19 18:10:40 2020 -0700
+++ b/render_sdl.c	Sun Oct 11 18:01:48 2020 -0700
@@ -172,7 +172,13 @@
 void render_audio_created(audio_source *source)
 {
 	if (sync_src == SYNC_AUDIO) {
-		SDL_PauseAudio(0);
+		//SDL_PauseAudio acquires the audio device lock, which is held while the callback runs
+		//since our callback can itself be stuck waiting on the audio_ready condition variable
+		//calling SDL_PauseAudio(0) again for audio sources after the first can deadlock
+		//fortunately SDL_GetAudioStatus does not acquire the lock so is safe to call here
+		if (SDL_GetAudioStatus() == SDL_AUDIO_PAUSED) {
+			SDL_PauseAudio(0);
+		}
 	}
 	if (current_system && sync_src == SYNC_AUDIO_THREAD) {
 		system_request_exit(current_system, 0);
@@ -195,7 +201,13 @@
 void render_source_resumed(audio_source *src)
 {
 	if (sync_src == SYNC_AUDIO) {
-		SDL_PauseAudio(0);
+		//SDL_PauseAudio acquires the audio device lock, which is held while the callback runs
+		//since our callback can itself be stuck waiting on the audio_ready condition variable
+		//calling SDL_PauseAudio(0) again for audio sources after the first can deadlock
+		//fortunately SDL_GetAudioStatus does not acquire the lock so is safe to call here
+		if (SDL_GetAudioStatus() == SDL_AUDIO_PAUSED) {
+			SDL_PauseAudio(0);
+		}
 	}
 	if (current_system && sync_src == SYNC_AUDIO_THREAD) {
 		system_request_exit(current_system, 0);