From 865dd04068698eaee066cfda56c91049125eeecb Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Mon, 23 Oct 2023 23:59:03 -0400
Subject: [PATCH] pulseaudio: Don't use a hash for device change detection.
Both strings are _right there_ for comparing, so we can just set a flag to
note the device definitely changed.
Also simplified string management further; hotplug thread now makes a copy
of the string before releasing the lock if there was a change event, so when
the lock releases further events don't see a NULL and assume it's a new
device, causing a lot of work to ripple out and decide nothing has changed,
until the system stabilizes again. Now, it just does the right thing once.
---
src/audio/pulseaudio/SDL_pulseaudio.c | 80 +++++++++++++--------------
1 file changed, 40 insertions(+), 40 deletions(-)
diff --git a/src/audio/pulseaudio/SDL_pulseaudio.c b/src/audio/pulseaudio/SDL_pulseaudio.c
index 6dab00028630..0a4d231efc01 100644
--- a/src/audio/pulseaudio/SDL_pulseaudio.c
+++ b/src/audio/pulseaudio/SDL_pulseaudio.c
@@ -58,8 +58,8 @@ static SDL_AtomicInt pulseaudio_hotplug_thread_active;
// 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 SDL_bool default_sink_changed = SDL_FALSE;
+static SDL_bool default_source_changed = SDL_FALSE;
static const char *(*PULSEAUDIO_pa_get_library_version)(void);
@@ -807,25 +807,21 @@ static void ServerInfoCallback(pa_context *c, const pa_server_info *i, void *dat
{
//SDL_Log("PULSEAUDIO ServerInfoCallback!");
- 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) {
+ if (!default_sink_path || (SDL_strcmp(default_sink_path, i->default_sink_name) != 0)) {
char *str = SDL_strdup(i->default_sink_name);
if (str) {
SDL_free(default_sink_path);
default_sink_path = str;
- default_sink_hash = hash;
+ default_sink_changed = SDL_TRUE;
}
}
- hash = SDL_HashString(i->default_source_name, NULL);
- if (hash != default_source_hash) {
+ if (!default_source_path || (SDL_strcmp(default_source_path, i->default_source_name) != 0)) {
char *str = SDL_strdup(i->default_source_name);
if (str) {
SDL_free(default_source_path);
default_source_path = str;
- default_source_hash = hash;
+ default_source_changed = SDL_TRUE;
}
}
@@ -876,22 +872,25 @@ 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 *new_device_path, Uint32 *prev_hash, Uint32 new_hash)
+static SDL_bool CheckDefaultDevice(const SDL_bool changed, char *device_path)
{
- 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.
- *prev_hash = new_hash;
- SDL_DefaultAudioDeviceChanged(device);
- }
+ if (!changed) {
+ return SDL_FALSE; // nothing's happening, leave the flag marked as unchanged.
+ } else if (!device_path) {
+ return SDL_TRUE; // check again later, we don't have a device name...
+ }
+
+ SDL_AudioDevice *device = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, device_path);
+ if (device) { // if NULL, we might still be waiting for a SinkInfoCallback or something, we'll try later.
+ SDL_DefaultAudioDeviceChanged(device);
+ return SDL_FALSE; // changing complete, set flag to unchanged for future tests.
}
+ return SDL_TRUE; // couldn't find the changed device, leave it marked as changed to try again later.
}
// 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);
@@ -911,27 +910,23 @@ 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 *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;
+ SDL_bool check_default_sink = default_sink_changed;
+ SDL_bool check_default_source = default_source_changed;
+ char *current_default_sink = check_default_sink ? SDL_strdup(default_sink_path) : NULL;
+ char *current_default_source = check_default_source ? SDL_strdup(default_source_path) : NULL;
+ default_sink_changed = default_source_changed = SDL_FALSE;
PULSEAUDIO_pa_threaded_mainloop_unlock(pulseaudio_threaded_mainloop);
- CheckDefaultDevice(current_default_sink, &prev_default_sink_hash, current_default_sink_hash);
- CheckDefaultDevice(current_default_source, &prev_default_source_hash, current_default_source_hash);
+ check_default_sink = CheckDefaultDevice(check_default_sink, current_default_sink);
+ check_default_source = CheckDefaultDevice(check_default_source, current_default_source);
PULSEAUDIO_pa_threaded_mainloop_lock(pulseaudio_threaded_mainloop);
- 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.
- }
+ // free our copies (which will be NULL if nothing changed)
+ SDL_free(current_default_sink);
+ SDL_free(current_default_source);
- 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.
- }
+ // set these to true if we didn't handle the change OR there was _another_ change while we were working unlocked.
+ default_sink_changed = (default_sink_changed || check_default_sink) ? SDL_TRUE : SDL_FALSE;
+ default_source_changed = (default_source_changed || check_default_source) ? SDL_TRUE : SDL_FALSE;
}
if (op) {
@@ -953,8 +948,13 @@ 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);
- *default_output = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, default_sink_path);
- *default_capture = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, default_source_path);
+ if (default_sink_path) {
+ *default_output = SDL_FindPhysicalAudioDeviceByCallback(FindAudioDeviceByPath, default_sink_path);
+ }
+
+ if (default_source_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);
@@ -988,10 +988,10 @@ static void PULSEAUDIO_Deinitialize(void)
SDL_free(default_sink_path);
default_sink_path = NULL;
- default_sink_hash = 0;
+ default_sink_changed = SDL_FALSE;
SDL_free(default_source_path);
default_source_path = NULL;
- default_source_hash = 0;
+ default_source_changed = SDL_FALSE;
UnloadPulseAudioLibrary();
}