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alsa: use udev if available instead of a hotplug thread 

This makes detecting audio device changes more responsive.
This commit is contained in:
Sam Lantinga 2025-06-20 15:23:59 -07:00 committed by Ryan C. Gordon
parent 051ce0ff89
commit e68f5ca99a
1 changed files with 66 additions and 3 deletions
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69
src/audio/alsa/SDL_alsa_audio.c
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@ -38,6 +38,7 @@
#include "../SDL_sysaudio.h"
#include "SDL_alsa_audio.h"
#include "../../core/linux/SDL_udev.h"
#if SDL_ALSA_DEBUG
#define LOGDEBUG(...) SDL_LogDebug(SDL_LOG_CATEGORY_AUDIO, "ALSA: " __VA_ARGS__)
@ -1441,6 +1442,65 @@ static int SDLCALL ALSA_HotplugThread(void *arg)
}
#endif
#ifdef SDL_USE_LIBUDEV
static bool udev_initialized;
static void ALSA_udev_callback(SDL_UDEV_deviceevent udev_type, int udev_class, const char *devpath)
{
if (!devpath) {
return;
}
switch (udev_type) {
case SDL_UDEV_DEVICEADDED:
ALSA_HotplugIteration(NULL, NULL);
break;
case SDL_UDEV_DEVICEREMOVED:
ALSA_HotplugIteration(NULL, NULL);
break;
default:
break;
}
}
static bool ALSA_start_udev()
{
udev_initialized = SDL_UDEV_Init();
if (udev_initialized) {
// Set up the udev callback
if (!SDL_UDEV_AddCallback(ALSA_udev_callback)) {
SDL_UDEV_Quit();
udev_initialized = false;
}
}
return udev_initialized;
}
static void ALSA_stop_udev()
{
if (udev_initialized) {
SDL_UDEV_DelCallback(ALSA_udev_callback);
SDL_UDEV_Quit();
udev_initialized = false;
}
}
#else
static bool ALSA_start_udev()
{
return false;
}
static void ALSA_stop_udev()
{
}
#endif // SDL_USE_LIBUDEV
static void ALSA_DetectDevices(SDL_AudioDevice **default_playback, SDL_AudioDevice **default_recording)
{
ALSA_guess_device_prefix();
@ -1456,11 +1516,13 @@ static void ALSA_DetectDevices(SDL_AudioDevice **default_playback, SDL_AudioDevi
*default_recording = SDL_AddAudioDevice(/*recording=*/true, "ALSA default recording device", NULL, (void *)&default_recording_handle);
}
if (!ALSA_start_udev()) {
#if SDL_ALSA_HOTPLUG_THREAD
SDL_SetAtomicInt(&ALSA_hotplug_shutdown, 0);
ALSA_hotplug_thread = SDL_CreateThread(ALSA_HotplugThread, "SDLHotplugALSA", NULL);
// if the thread doesn't spin, oh well, you just don't get further hotplug events.
SDL_SetAtomicInt(&ALSA_hotplug_shutdown, 0);
ALSA_hotplug_thread = SDL_CreateThread(ALSA_HotplugThread, "SDLHotplugALSA", NULL);
// if the thread doesn't spin, oh well, you just don't get further hotplug events.
#endif
}
}
static void ALSA_DeinitializeStart(void)
@ -1475,6 +1537,7 @@ static void ALSA_DeinitializeStart(void)
ALSA_hotplug_thread = NULL;
}
#endif
ALSA_stop_udev();
// Shutting down! Clean up any data we've gathered.
for (dev = hotplug_devices; dev; dev = next) {