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pulseaudio: Simplified default device change detection code. 

This reduces allocations, simplifies some code, and makes it quick to decide
from the hotplug thread if there was _actually_ a device change.
main
Ryan C. Gordon 2023-10-23 22:01:05 -04:00
parent e57fef8f0b
commit a774694be0
No known key found for this signature in database
GPG Key ID: FA148B892AB48044
1 changed files with 48 additions and 38 deletions
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86
src/audio/pulseaudio/SDL_pulseaudio.c
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@ -54,10 +54,12 @@ static SDL_Thread *pulseaudio_hotplug_thread = NULL;
static SDL_AtomicInt pulseaudio_hotplug_thread_active;
// These are the OS identifiers (i.e. ALSA strings)...these are allocated in a callback
// when the default changes, and claimed/free'd by the hotplug thread when it alerts SDL
// when the default changes, and noticed by the hotplug thread when it alerts SDL
// to the change.
static char *default_sink_path = NULL;
static char *default_source_path = NULL;
static Uint32 default_sink_hash = 0;
static Uint32 default_source_hash = 0;
static const char *(*PULSEAUDIO_pa_get_library_version)(void);
@ -804,11 +806,28 @@ static void SourceInfoCallback(pa_context *c, const pa_source_info *i, int is_la
static void ServerInfoCallback(pa_context *c, const pa_server_info *i, void *data)
{
//SDL_Log("PULSEAUDIO ServerInfoCallback!");
SDL_free(default_sink_path);
default_sink_path = SDL_strdup(i->default_sink_name);
SDL_free(default_source_path);
default_source_path = SDL_strdup(i->default_source_name);
Uint32 hash; // just hash the strings so we can decide if this is different without having to manage a string copy.
hash = SDL_HashString(i->default_sink_name, NULL);
if (hash != default_sink_hash) {
char *str = SDL_strdup(i->default_sink_name);
if (str) {
SDL_free(default_sink_path);
default_sink_path = str;
default_sink_hash = hash;
}
}
hash = SDL_HashString(i->default_source_name, NULL);
if (hash != default_source_hash) {
char *str = SDL_strdup(i->default_source_name);
if (str) {
SDL_free(default_source_path);
default_source_path = str;
default_source_hash = hash;
}
}
PULSEAUDIO_pa_threaded_mainloop_signal(pulseaudio_threaded_mainloop, 0);
}
@ -857,14 +876,12 @@ static void HotplugCallback(pa_context *c, pa_subscription_event_type_t t, uint3
PULSEAUDIO_pa_threaded_mainloop_signal(pulseaudio_threaded_mainloop, 0);
}
static void CheckDefaultDevice(char **pnew_device)
static void CheckDefaultDevice(char *new_device_path, Uint32 *prev_hash, Uint32 new_hash)
{
char *new_device = *pnew_device;
if (new_device) {
SDL_AudioDevice *device = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, new_device);
if (new_device_path && (*prev_hash != new_hash)) {
SDL_AudioDevice *device = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, new_device_path);
if (device) { // if NULL, we might still be waiting for a SinkInfoCallback or something, we'll try later.
SDL_free(new_device); // done with this, free it.
*pnew_device = NULL;
*prev_hash = new_hash;
SDL_DefaultAudioDeviceChanged(device);
}
}
@ -873,6 +890,8 @@ static void CheckDefaultDevice(char **pnew_device)
// this runs as a thread while the Pulse target is initialized to catch hotplug events.
static int SDLCALL HotplugThread(void *data)
{
Uint32 prev_default_sink_hash = default_sink_hash;
Uint32 prev_default_source_hash = default_source_hash;
pa_operation *op;
SDL_SetThreadPriority(SDL_THREAD_PRIORITY_LOW);
@ -892,28 +911,26 @@ static int SDLCALL HotplugThread(void *data)
}
// Update default devices; don't hold the pulse lock during this, since it could deadlock vs a playing device that we're about to lock here.
char *new_default_sink = default_sink_path;
char *new_default_source = default_source_path;
char *current_default_sink = default_sink_path;
char *current_default_source = default_source_path;
default_sink_path = default_source_path = NULL; // make sure we own these before releasing the lock.
const Uint32 current_default_sink_hash = default_sink_hash;
const Uint32 current_default_source_hash = default_source_hash;
PULSEAUDIO_pa_threaded_mainloop_unlock(pulseaudio_threaded_mainloop);
CheckDefaultDevice(&new_default_sink);
CheckDefaultDevice(&new_default_source);
CheckDefaultDevice(current_default_sink, &prev_default_sink_hash, current_default_sink_hash);
CheckDefaultDevice(current_default_source, &prev_default_source_hash, current_default_source_hash);
PULSEAUDIO_pa_threaded_mainloop_lock(pulseaudio_threaded_mainloop);
if (new_default_sink) { // couldn't find this device, try again later.
if (default_sink_path) {
SDL_free(new_default_sink); // uhoh, something else became default while we were unlocked. Dump ours.
} else {
default_sink_path = new_default_sink; // put string back to try again later.
}
if (default_sink_path) {
SDL_free(current_default_sink); // uhoh, something else became default while we were unlocked. Dump ours.
} else {
default_sink_path = current_default_sink; // put string back for later.
}
if (new_default_source) { // couldn't find this device, try again later.
if (default_source_path) {
SDL_free(new_default_source); // uhoh, something else became default while we were unlocked. Dump ours.
} else {
default_source_path = new_default_source; // put string back to try again later.
}
if (default_source_path) {
SDL_free(current_default_source); // uhoh, something else became default while we were unlocked. Dump ours.
} else {
default_source_path = current_default_source; // put string back for later.
}
}
@ -936,17 +953,8 @@ static void PULSEAUDIO_DetectDevices(SDL_AudioDevice **default_output, SDL_Audio
WaitForPulseOperation(PULSEAUDIO_pa_context_get_source_info_list(pulseaudio_context, SourceInfoCallback, NULL));
PULSEAUDIO_pa_threaded_mainloop_unlock(pulseaudio_threaded_mainloop);
if (default_sink_path) {
*default_output = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, default_sink_path);
SDL_free(default_sink_path);
default_sink_path = NULL;
}
if (default_source_path) {
*default_capture = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, default_source_path);
SDL_free(default_source_path);
default_source_path = NULL;
}
*default_output = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, default_sink_path);
*default_capture = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, default_source_path);
// ok, we have a sane list, let's set up hotplug notifications now...
SDL_AtomicSet(&pulseaudio_hotplug_thread_active, 1);
@ -980,8 +988,10 @@ static void PULSEAUDIO_Deinitialize(void)
SDL_free(default_sink_path);
default_sink_path = NULL;
default_sink_hash = 0;
SDL_free(default_source_path);
default_source_path = NULL;
default_source_hash = 0;
UnloadPulseAudioLibrary();
}