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audio: Renamed device_hash_lock to subsystem_rwlock.

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It protects more than the device hashes!
This commit is contained in:
Ryan C. Gordon
2025-08-25 11:35:37 -04:00
parent 226fecff78
commit 01d94ca9de
2 changed files with 66 additions and 68 deletions
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132
src/audio/SDL_audio.c
View File

@@ -186,16 +186,15 @@ void OnAudioStreamCreated(SDL_AudioStream *stream)
// NOTE that you can create an audio stream without initializing the audio subsystem,
// but it will not be automatically destroyed during a later call to SDL_Quit!
// You must explicitly destroy it yourself!
if (current_audio.device_hash_lock) {
// this isn't really part of the "device list" but it's a convenient lock to use here.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
if (current_audio.subsystem_rwlock) {
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
if (current_audio.existing_streams) {
current_audio.existing_streams->prev = stream;
}
stream->prev = NULL;
stream->next = current_audio.existing_streams;
current_audio.existing_streams = stream;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
}
@@ -206,9 +205,8 @@ void OnAudioStreamDestroy(SDL_AudioStream *stream)
// NOTE that you can create an audio stream without initializing the audio subsystem,
// but it will not be automatically destroyed during a later call to SDL_Quit!
// You must explicitly destroy it yourself!
if (current_audio.device_hash_lock) {
// this isn't really part of the "device list" but it's a convenient lock to use here.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
if (current_audio.subsystem_rwlock) {
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
if (stream->prev) {
stream->prev->next = stream->next;
}
@@ -218,7 +216,7 @@ void OnAudioStreamDestroy(SDL_AudioStream *stream)
if (stream == current_audio.existing_streams) {
current_audio.existing_streams = stream->next;
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
}
@@ -410,7 +408,7 @@ static SDL_LogicalAudioDevice *ObtainLogicalAudioDevice(SDL_AudioDeviceID devid,
// bit #1 of devid is set for physical devices and unset for logical.
const bool islogical = !(devid & (1<<1));
if (islogical) { // don't bother looking if it's not a logical device id value.
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
SDL_FindInHashTable(current_audio.device_hash_logical, (const void *) (uintptr_t) devid, (const void **) &logdev);
if (logdev) {
SDL_assert(logdev->instance_id == devid);
@@ -418,10 +416,10 @@ static SDL_LogicalAudioDevice *ObtainLogicalAudioDevice(SDL_AudioDeviceID devid,
SDL_assert(device != NULL);
RefPhysicalAudioDevice(device); // reference it, in case the logical device migrates to a new default.
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (logdev) {
// we have to release the device_hash_lock before we take the device lock, to avoid deadlocks, so do a loop
// we have to release the subsystem_rwlock before we take the device lock, to avoid deadlocks, so do a loop
// to make sure the correct physical device gets locked, in case we're in a race with the default changing.
while (true) {
SDL_LockMutex(device->lock);
@@ -461,10 +459,10 @@ static SDL_AudioDevice *ObtainPhysicalAudioDevice(SDL_AudioDeviceID devid) // !
} else if (!SDL_GetCurrentAudioDriver()) { // (the `islogical` path, above, checks this in ObtainLogicalAudioDevice.)
SDL_SetError("Audio subsystem is not initialized");
} else {
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
SDL_FindInHashTable(current_audio.device_hash_physical, (const void *) (uintptr_t) devid, (const void **) &device);
SDL_assert(!device || (device->instance_id == devid));
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (!device) {
SDL_SetError("Invalid audio device instance ID");
@@ -486,13 +484,13 @@ static SDL_AudioDevice *ObtainPhysicalAudioDeviceDefaultAllowed(SDL_AudioDeviceI
const SDL_AudioDeviceID orig_devid = devid;
while (true) {
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
if (orig_devid == SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK) {
devid = current_audio.default_playback_device_id;
} else if (orig_devid == SDL_AUDIO_DEVICE_DEFAULT_RECORDING) {
devid = current_audio.default_recording_device_id;
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (devid == 0) {
SDL_SetError("No default audio device available");
@@ -506,13 +504,13 @@ static SDL_AudioDevice *ObtainPhysicalAudioDeviceDefaultAllowed(SDL_AudioDeviceI
// make sure the default didn't change while we were waiting for the lock...
bool got_it = false;
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
if ((orig_devid == SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK) && (devid == current_audio.default_playback_device_id)) {
got_it = true;
} else if ((orig_devid == SDL_AUDIO_DEVICE_DEFAULT_RECORDING) && (devid == current_audio.default_recording_device_id)) {
got_it = true;
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (got_it) {
return device;
@@ -530,9 +528,9 @@ static void DestroyLogicalAudioDevice(SDL_LogicalAudioDevice *logdev)
{
// Remove ourselves from the device_hash hashtable.
if (current_audio.device_hash_logical) { // will be NULL while shutting down.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
SDL_RemoveFromHashTable(current_audio.device_hash_logical, (const void *) (uintptr_t) logdev->instance_id);
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
// remove ourselves from the physical device's list of logical devices.
@@ -593,11 +591,11 @@ void UnrefPhysicalAudioDevice(SDL_AudioDevice *device)
{
if (SDL_AtomicDecRef(&device->refcount)) {
// take it out of the device list.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
if (SDL_RemoveFromHashTable(current_audio.device_hash_physical, (const void *) (uintptr_t) device->instance_id)) {
SDL_AddAtomicInt(device->recording ? &current_audio.recording_device_count : &current_audio.playback_device_count, -1);
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
DestroyPhysicalAudioDevice(device); // ...and nuke it.
}
}
@@ -611,9 +609,9 @@ static SDL_AudioDevice *CreatePhysicalAudioDevice(const char *name, bool recordi
{
SDL_assert(name != NULL);
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
const int shutting_down = SDL_GetAtomicInt(&current_audio.shutting_down);
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (shutting_down) {
return NULL; // we're shutting down, don't add any devices that are hotplugged at the last possible moment.
}
@@ -655,7 +653,7 @@ static SDL_AudioDevice *CreatePhysicalAudioDevice(const char *name, bool recordi
device->instance_id = AssignAudioDeviceInstanceId(recording, /*islogical=*/false);
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
if (SDL_InsertIntoHashTable(current_audio.device_hash_physical, (const void *) (uintptr_t) device->instance_id, device, false)) {
SDL_AddAtomicInt(device_count, 1);
} else {
@@ -665,7 +663,7 @@ static SDL_AudioDevice *CreatePhysicalAudioDevice(const char *name, bool recordi
SDL_free(device);
device = NULL;
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
RefPhysicalAudioDevice(device); // unref'd on device disconnect.
return device;
@@ -713,12 +711,12 @@ SDL_AudioDevice *SDL_AddAudioDevice(bool recording, const char *name, const SDL_
p->type = SDL_EVENT_AUDIO_DEVICE_ADDED;
p->devid = device->instance_id;
p->next = NULL;
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
SDL_assert(current_audio.pending_events_tail != NULL);
SDL_assert(current_audio.pending_events_tail->next == NULL);
current_audio.pending_events_tail->next = p;
current_audio.pending_events_tail = p;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
}
@@ -742,10 +740,10 @@ void SDL_AudioDeviceDisconnected(SDL_AudioDevice *device)
ObtainPhysicalAudioDeviceObj(device);
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
const SDL_AudioDeviceID devid = device->instance_id;
const bool is_default_device = ((devid == current_audio.default_playback_device_id) || (devid == current_audio.default_recording_device_id));
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
const bool first_disconnect = SDL_CompareAndSwapAtomicInt(&device->zombie, 0, 1);
if (first_disconnect) { // if already disconnected this device, don't do it twice.
@@ -790,12 +788,12 @@ void SDL_AudioDeviceDisconnected(SDL_AudioDevice *device)
if (first_disconnect) {
if (pending.next) { // NULL if event is disabled or disaster struck.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
SDL_assert(current_audio.pending_events_tail != NULL);
SDL_assert(current_audio.pending_events_tail->next == NULL);
current_audio.pending_events_tail->next = pending.next;
current_audio.pending_events_tail = pending_tail;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
UnrefPhysicalAudioDevice(device);
@@ -900,9 +898,9 @@ static SDL_AudioDevice *GetFirstAddedAudioDevice(const bool recording)
// (Device IDs increase as new devices are added, so the first device added has the lowest SDL_AudioDeviceID value.)
FindLowestDeviceIDData data = { recording, highest, NULL };
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
SDL_IterateHashTable(current_audio.device_hash_physical, FindLowestDeviceID, &data);
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
return data.result;
}
@@ -926,21 +924,21 @@ bool SDL_InitAudio(const char *driver_name)
SDL_ChooseAudioConverters();
SDL_SetupAudioResampler();
SDL_RWLock *device_hash_lock = SDL_CreateRWLock(); // create this early, so if it fails we don't have to tear down the whole audio subsystem.
if (!device_hash_lock) {
SDL_RWLock *subsystem_rwlock = SDL_CreateRWLock(); // create this early, so if it fails we don't have to tear down the whole audio subsystem.
if (!subsystem_rwlock) {
return false;
}
SDL_HashTable *device_hash_physical = SDL_CreateHashTable(0, false, HashAudioDeviceID, SDL_KeyMatchID, NULL, NULL);
if (!device_hash_physical) {
SDL_DestroyRWLock(device_hash_lock);
SDL_DestroyRWLock(subsystem_rwlock);
return false;
}
SDL_HashTable *device_hash_logical = SDL_CreateHashTable(0, false, HashAudioDeviceID, SDL_KeyMatchID, NULL, NULL);
if (!device_hash_logical) {
SDL_DestroyHashTable(device_hash_physical);
SDL_DestroyRWLock(device_hash_lock);
SDL_DestroyRWLock(subsystem_rwlock);
return false;
}
@@ -957,7 +955,7 @@ bool SDL_InitAudio(const char *driver_name)
const char *driver_attempt = driver_name_copy;
if (!driver_name_copy) {
SDL_DestroyRWLock(device_hash_lock);
SDL_DestroyRWLock(subsystem_rwlock);
SDL_DestroyHashTable(device_hash_physical);
SDL_DestroyHashTable(device_hash_logical);
return false;
@@ -981,7 +979,7 @@ bool SDL_InitAudio(const char *driver_name)
tried_to_init = true;
SDL_zero(current_audio);
current_audio.pending_events_tail = &current_audio.pending_events;
current_audio.device_hash_lock = device_hash_lock;
current_audio.subsystem_rwlock = subsystem_rwlock;
current_audio.device_hash_physical = device_hash_physical;
current_audio.device_hash_logical = device_hash_logical;
if (bootstrap[i]->init(&current_audio.impl)) {
@@ -1006,7 +1004,7 @@ bool SDL_InitAudio(const char *driver_name)
tried_to_init = true;
SDL_zero(current_audio);
current_audio.pending_events_tail = &current_audio.pending_events;
current_audio.device_hash_lock = device_hash_lock;
current_audio.subsystem_rwlock = subsystem_rwlock;
current_audio.device_hash_physical = device_hash_physical;
current_audio.device_hash_logical = device_hash_logical;
if (bootstrap[i]->init(&current_audio.impl)) {
@@ -1029,7 +1027,7 @@ bool SDL_InitAudio(const char *driver_name)
}
}
SDL_DestroyRWLock(device_hash_lock);
SDL_DestroyRWLock(subsystem_rwlock);
SDL_DestroyHashTable(device_hash_physical);
SDL_DestroyHashTable(device_hash_logical);
SDL_zero(current_audio);
@@ -1097,7 +1095,7 @@ void SDL_QuitAudio(void)
}
}
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
SDL_SetAtomicInt(&current_audio.shutting_down, 1);
SDL_HashTable *device_hash_physical = current_audio.device_hash_physical;
SDL_HashTable *device_hash_logical = current_audio.device_hash_logical;
@@ -1106,7 +1104,7 @@ void SDL_QuitAudio(void)
current_audio.pending_events.next = NULL;
SDL_SetAtomicInt(&current_audio.playback_device_count, 0);
SDL_SetAtomicInt(&current_audio.recording_device_count, 0);
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
SDL_PendingAudioDeviceEvent *pending_next = NULL;
for (SDL_PendingAudioDeviceEvent *i = pending_events; i; i = pending_next) {
@@ -1120,7 +1118,7 @@ void SDL_QuitAudio(void)
// Free the driver data
current_audio.impl.Deinitialize();
SDL_DestroyRWLock(current_audio.device_hash_lock);
SDL_DestroyRWLock(current_audio.subsystem_rwlock);
SDL_DestroyHashTable(device_hash_physical);
SDL_DestroyHashTable(device_hash_logical);
@@ -1437,7 +1435,7 @@ static bool SDLCALL CountAudioDevices(void *userdata, const SDL_HashTable *table
SDL_assert(isphysical);
if (devid_recording == data->recording) {
SDL_assert(data->devs_seen < data->num_devices);
SDL_AudioDevice *device = (SDL_AudioDevice *) value; // this is normally risky, but we hold the device_hash_lock here.
SDL_AudioDevice *device = (SDL_AudioDevice *) value; // this is normally risky, but we hold the subsystem_rwlock here.
const bool zombie = SDL_GetAtomicInt(&device->zombie) != 0;
if (zombie) {
data->devs_skipped++;
@@ -1454,7 +1452,7 @@ static SDL_AudioDeviceID *GetAudioDevices(int *count, bool recording)
int num_devices = 0;
if (SDL_GetCurrentAudioDriver()) {
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
{
num_devices = SDL_GetAtomicInt(recording ? &current_audio.recording_device_count : &current_audio.playback_device_count);
result = (SDL_AudioDeviceID *) SDL_malloc((num_devices + 1) * sizeof (SDL_AudioDeviceID));
@@ -1466,7 +1464,7 @@ static SDL_AudioDeviceID *GetAudioDevices(int *count, bool recording)
result[num_devices] = 0; // null-terminated.
}
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
} else {
SDL_SetError("Audio subsystem is not initialized");
}
@@ -1523,9 +1521,9 @@ SDL_AudioDevice *SDL_FindPhysicalAudioDeviceByCallback(bool (*callback)(SDL_Audi
}
FindAudioDeviceByCallbackData data = { callback, userdata, NULL };
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
SDL_IterateHashTable(current_audio.device_hash_physical, FindAudioDeviceByCallback, &data);
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (!data.retval) {
SDL_SetError("Device not found");
@@ -1557,8 +1555,8 @@ const char *SDL_GetAudioDeviceName(SDL_AudioDeviceID devid)
// This does not call ObtainPhysicalAudioDevice() because the device's name never changes, so
// it doesn't have to lock the whole device. However, just to make sure the device pointer itself
// remains valid (in case the device is unplugged at the wrong moment), we hold the
// device_hash_lock while we copy the string.
SDL_LockRWLockForReading(current_audio.device_hash_lock);
// subsystem_rwlock while we copy the string.
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
SDL_FindInHashTable(islogical ? current_audio.device_hash_logical : current_audio.device_hash_physical, (const void *) (uintptr_t) devid, &vdev);
if (!vdev) {
SDL_SetError("Invalid audio device instance ID");
@@ -1571,7 +1569,7 @@ const char *SDL_GetAudioDeviceName(SDL_AudioDeviceID devid)
SDL_assert(device->instance_id == devid);
result = SDL_GetPersistentString(device->name);
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
return result;
@@ -1884,9 +1882,9 @@ SDL_AudioDeviceID SDL_OpenAudioDevice(SDL_AudioDeviceID devid, const SDL_AudioSp
ReleaseAudioDevice(device);
if (result) {
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
const bool inserted = SDL_InsertIntoHashTable(current_audio.device_hash_logical, (const void *) (uintptr_t) result, logdev, false);
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (!inserted) {
SDL_CloseAudioDevice(result);
result = 0;
@@ -2336,7 +2334,7 @@ void SDL_DefaultAudioDeviceChanged(SDL_AudioDevice *new_default_device)
const bool recording = new_default_device->recording;
// change the official default over right away, so new opens will go to the new device.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
const SDL_AudioDeviceID current_devid = recording ? current_audio.default_recording_device_id : current_audio.default_playback_device_id;
const bool is_already_default = (new_default_device->instance_id == current_devid);
if (!is_already_default) {
@@ -2346,7 +2344,7 @@ void SDL_DefaultAudioDeviceChanged(SDL_AudioDevice *new_default_device)
current_audio.default_playback_device_id = new_default_device->instance_id;
}
}
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (is_already_default) {
return; // this is already the default.
@@ -2412,8 +2410,8 @@ void SDL_DefaultAudioDeviceChanged(SDL_AudioDevice *new_default_device)
continue; // not opened as a default, leave it on the current physical device.
}
// now migrate the logical device. Hold device_hash_lock so ObtainLogicalAudioDevice doesn't get a device in the middle of transition.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
// now migrate the logical device. Hold subsystem_rwlock so ObtainLogicalAudioDevice doesn't get a device in the middle of transition.
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
if (logdev->next) {
logdev->next->prev = logdev->prev;
}
@@ -2428,7 +2426,7 @@ void SDL_DefaultAudioDeviceChanged(SDL_AudioDevice *new_default_device)
logdev->prev = NULL;
logdev->next = new_default_device->logical_devices;
new_default_device->logical_devices = logdev;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
SDL_assert(SDL_GetAtomicInt(&current_default_device->refcount) > 1); // we should hold at least one extra reference to this device, beyond logical devices, during this phase...
RefPhysicalAudioDevice(new_default_device);
@@ -2470,12 +2468,12 @@ void SDL_DefaultAudioDeviceChanged(SDL_AudioDevice *new_default_device)
}
if (pending.next) {
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
SDL_assert(current_audio.pending_events_tail != NULL);
SDL_assert(current_audio.pending_events_tail->next == NULL);
current_audio.pending_events_tail->next = pending.next;
current_audio.pending_events_tail = pending_tail;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
}
@@ -2552,12 +2550,12 @@ bool SDL_AudioDeviceFormatChangedAlreadyLocked(SDL_AudioDevice *device, const SD
}
if (pending.next) {
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
SDL_assert(current_audio.pending_events_tail != NULL);
SDL_assert(current_audio.pending_events_tail->next == NULL);
current_audio.pending_events_tail->next = pending.next;
current_audio.pending_events_tail = pending_tail;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
}
}
@@ -2579,20 +2577,20 @@ bool SDL_AudioDeviceFormatChanged(SDL_AudioDevice *device, const SDL_AudioSpec *
// ("UpdateSubsystem" is the same naming that the other things that hook into PumpEvents use.)
void SDL_UpdateAudio(void)
{
SDL_LockRWLockForReading(current_audio.device_hash_lock);
SDL_LockRWLockForReading(current_audio.subsystem_rwlock);
SDL_PendingAudioDeviceEvent *pending_events = current_audio.pending_events.next;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
if (!pending_events) {
return; // nothing to do, check next time.
}
// okay, let's take this whole list of events so we can dump the lock, and new ones can queue up for a later update.
SDL_LockRWLockForWriting(current_audio.device_hash_lock);
SDL_LockRWLockForWriting(current_audio.subsystem_rwlock);
pending_events = current_audio.pending_events.next; // in case this changed...
current_audio.pending_events.next = NULL;
current_audio.pending_events_tail = &current_audio.pending_events;
SDL_UnlockRWLock(current_audio.device_hash_lock);
SDL_UnlockRWLock(current_audio.subsystem_rwlock);
SDL_PendingAudioDeviceEvent *pending_next = NULL;
for (SDL_PendingAudioDeviceEvent *i = pending_events; i; i = pending_next) {

2
src/audio/SDL_sysaudio.h
View File

@@ -183,7 +183,7 @@ typedef struct SDL_AudioDriver
const char *name; // The name of this audio driver
const char *desc; // The description of this audio driver
SDL_AudioDriverImpl impl; // the backend's interface
SDL_RWLock *device_hash_lock; // A rwlock that protects `device_hash*` and some other things.
SDL_RWLock *subsystem_rwlock; // A rwlock that protects several things in the audio subsystem (device hashtables, etc).
SDL_HashTable *device_hash_physical; // the collection of currently-available audio devices (recording and playback), for mapping SDL_AudioDeviceID to an SDL_AudioDevice*.
SDL_HashTable *device_hash_logical; // the collection of currently-available audio devices (recording and playback), for mapping SDL_AudioDeviceID to an SDL_LogicalAudioDevice*.
SDL_AudioStream *existing_streams; // a list of all existing SDL_AudioStreams.