Remove almost all instances of "volatile" keyword.
As Tiffany pointed out in Bugzilla, volatile is not useful for thread safety:
https://software.intel.com/en-us/blogs/2007/11/30/volatile-almost-useless-for-multi-threaded-programming/
Some of these volatiles didn't need to be, some were otherwise protected by
spinlocks or mutexes, and some got moved over to SDL_atomic_t data, etc.
Fixes Bugzilla #3220.
--- a/src/dynapi/SDL_dynapi.c Sat Jan 02 12:17:33 2016 -0800
+++ b/src/dynapi/SDL_dynapi.c Sun Jan 03 06:50:50 2016 -0500
@@ -293,7 +293,7 @@
* SDL_CreateThread() would also call this function before building the
* new thread).
*/
- static volatile SDL_bool already_initialized = SDL_FALSE;
+ static SDL_bool already_initialized = SDL_FALSE;
/* SDL_AtomicLock calls SDL mutex functions to emulate if
SDL_ATOMIC_DISABLED, which we can't do here, so in such a
--- a/src/events/SDL_events.c Sat Jan 02 12:17:33 2016 -0800
+++ b/src/events/SDL_events.c Sun Jan 03 06:50:50 2016 -0500
@@ -73,15 +73,15 @@
static struct
{
SDL_mutex *lock;
- volatile SDL_bool active;
- volatile int count;
- volatile int max_events_seen;
+ SDL_atomic_t active;
+ SDL_atomic_t count;
+ int max_events_seen;
SDL_EventEntry *head;
SDL_EventEntry *tail;
SDL_EventEntry *free;
SDL_SysWMEntry *wmmsg_used;
SDL_SysWMEntry *wmmsg_free;
-} SDL_EventQ = { NULL, SDL_TRUE, 0, 0, NULL, NULL, NULL, NULL, NULL };
+} SDL_EventQ = { NULL, { 1 }, { 0 }, 0, NULL, NULL, NULL, NULL, NULL };
/* Public functions */
@@ -98,7 +98,7 @@
SDL_LockMutex(SDL_EventQ.lock);
}
- SDL_EventQ.active = SDL_FALSE;
+ SDL_AtomicSet(&SDL_EventQ.active, 0);
if (report && SDL_atoi(report)) {
SDL_Log("SDL EVENT QUEUE: Maximum events in-flight: %d\n",
@@ -127,7 +127,7 @@
wmmsg = next;
}
- SDL_EventQ.count = 0;
+ SDL_AtomicSet(&SDL_EventQ.count, 0);
SDL_EventQ.max_events_seen = 0;
SDL_EventQ.head = NULL;
SDL_EventQ.tail = NULL;
@@ -171,7 +171,7 @@
SDL_EventQ.lock = SDL_CreateMutex();
}
if (SDL_EventQ.lock == NULL) {
- return (-1);
+ return -1;
}
#endif /* !SDL_THREADS_DISABLED */
@@ -180,9 +180,9 @@
SDL_EventState(SDL_TEXTEDITING, SDL_DISABLE);
SDL_EventState(SDL_SYSWMEVENT, SDL_DISABLE);
- SDL_EventQ.active = SDL_TRUE;
+ SDL_AtomicSet(&SDL_EventQ.active, 1);
- return (0);
+ return 0;
}
@@ -191,9 +191,11 @@
SDL_AddEvent(SDL_Event * event)
{
SDL_EventEntry *entry;
+ const int initial_count = SDL_AtomicGet(&SDL_EventQ.count);
+ int final_count;
- if (SDL_EventQ.count >= SDL_MAX_QUEUED_EVENTS) {
- SDL_SetError("Event queue is full (%d events)", SDL_EventQ.count);
+ if (initial_count >= SDL_MAX_QUEUED_EVENTS) {
+ SDL_SetError("Event queue is full (%d events)", initial_count);
return 0;
}
@@ -225,10 +227,10 @@
entry->prev = NULL;
entry->next = NULL;
}
- ++SDL_EventQ.count;
- if (SDL_EventQ.count > SDL_EventQ.max_events_seen) {
- SDL_EventQ.max_events_seen = SDL_EventQ.count;
+ final_count = SDL_AtomicAdd(&SDL_EventQ.count, 1) + 1;
+ if (final_count > SDL_EventQ.max_events_seen) {
+ SDL_EventQ.max_events_seen = final_count;
}
return 1;
@@ -256,8 +258,8 @@
entry->next = SDL_EventQ.free;
SDL_EventQ.free = entry;
- SDL_assert(SDL_EventQ.count > 0);
- --SDL_EventQ.count;
+ SDL_assert(SDL_AtomicGet(&SDL_EventQ.count) > 0);
+ SDL_AtomicAdd(&SDL_EventQ.count, -1);
}
/* Lock the event queue, take a peep at it, and unlock it */
@@ -268,7 +270,7 @@
int i, used;
/* Don't look after we've quit */
- if (!SDL_EventQ.active) {
+ if (!SDL_AtomicGet(&SDL_EventQ.active)) {
/* We get a few spurious events at shutdown, so don't warn then */
if (action != SDL_ADDEVENT) {
SDL_SetError("The event system has been shut down");
@@ -363,7 +365,7 @@
SDL_FlushEvents(Uint32 minType, Uint32 maxType)
{
/* Don't look after we've quit */
- if (!SDL_EventQ.active) {
+ if (!SDL_AtomicGet(&SDL_EventQ.active)) {
return;
}
--- a/src/haptic/windows/SDL_windowshaptic.c Sat Jan 02 12:17:33 2016 -0800
+++ b/src/haptic/windows/SDL_windowshaptic.c Sun Jan 03 06:50:50 2016 -0500
@@ -255,7 +255,7 @@
for (hapticitem = SDL_haptics; hapticitem; hapticitem = hapticitem->next) {
if ((hapticitem->hwdata->bXInputHaptic) && (hapticitem->hwdata->thread)) {
/* we _have_ to stop the thread before we free the XInput DLL! */
- hapticitem->hwdata->stopThread = 1;
+ SDL_AtomicSet(&hapticitem->hwdata->stopThread, 1);
SDL_WaitThread(hapticitem->hwdata->thread, NULL);
hapticitem->hwdata->thread = NULL;
}
--- a/src/haptic/windows/SDL_windowshaptic_c.h Sat Jan 02 12:17:33 2016 -0800
+++ b/src/haptic/windows/SDL_windowshaptic_c.h Sun Jan 03 06:50:50 2016 -0500
@@ -42,8 +42,8 @@
Uint8 userid; /* XInput userid index for this joystick */
SDL_Thread *thread;
SDL_mutex *mutex;
- volatile Uint32 stopTicks;
- volatile int stopThread;
+ Uint32 stopTicks;
+ SDL_atomic_t stopThread;
};
--- a/src/haptic/windows/SDL_xinputhaptic.c Sat Jan 02 12:17:33 2016 -0800
+++ b/src/haptic/windows/SDL_xinputhaptic.c Sun Jan 03 06:50:50 2016 -0500
@@ -146,7 +146,7 @@
{
struct haptic_hwdata *hwdata = (struct haptic_hwdata *) arg;
- while (!hwdata->stopThread) {
+ while (!SDL_AtomicGet(&hwdata->stopThread)) {
SDL_Delay(50);
SDL_LockMutex(hwdata->mutex);
/* If we're currently running and need to stop... */
@@ -261,7 +261,7 @@
void
SDL_XINPUT_HapticClose(SDL_Haptic * haptic)
{
- haptic->hwdata->stopThread = 1;
+ SDL_AtomicSet(&haptic->hwdata->stopThread, 1);
SDL_WaitThread(haptic->hwdata->thread, NULL);
SDL_DestroyMutex(haptic->hwdata->mutex);
}
--- a/src/timer/SDL_timer.c Sat Jan 02 12:17:33 2016 -0800
+++ b/src/timer/SDL_timer.c Sun Jan 03 06:50:50 2016 -0500
@@ -35,7 +35,7 @@
void *param;
Uint32 interval;
Uint32 scheduled;
- volatile SDL_bool canceled;
+ SDL_atomic_t canceled;
struct _SDL_Timer *next;
} SDL_Timer;
@@ -60,9 +60,9 @@
/* Data used to communicate with the timer thread */
SDL_SpinLock lock;
SDL_sem *sem;
- SDL_Timer * volatile pending;
- SDL_Timer * volatile freelist;
- volatile SDL_bool active;
+ SDL_Timer *pending;
+ SDL_Timer *freelist;
+ SDL_atomic_t active;
/* List of timers - this is only touched by the timer thread */
SDL_Timer *timers;
@@ -138,7 +138,7 @@
freelist_tail = NULL;
/* Check to see if we're still running, after maintenance */
- if (!data->active) {
+ if (!SDL_AtomicGet(&data->active)) {
break;
}
@@ -160,7 +160,7 @@
/* We're going to do something with this timer */
data->timers = current->next;
- if (current->canceled) {
+ if (SDL_AtomicGet(¤t->canceled)) {
interval = 0;
} else {
interval = current->callback(current->interval, current->param);
@@ -179,7 +179,7 @@
}
freelist_tail = current;
- current->canceled = SDL_TRUE;
+ SDL_AtomicSet(¤t->canceled, 1);
}
}
@@ -207,7 +207,7 @@
{
SDL_TimerData *data = &SDL_timer_data;
- if (!data->active) {
+ if (!SDL_AtomicGet(&data->active)) {
const char *name = "SDLTimer";
data->timermap_lock = SDL_CreateMutex();
if (!data->timermap_lock) {
@@ -220,7 +220,7 @@
return -1;
}
- data->active = SDL_TRUE;
+ SDL_AtomicSet(&data->active, 1);
/* !!! FIXME: this is nasty. */
#if defined(__WIN32__) && !defined(HAVE_LIBC)
#undef SDL_CreateThread
@@ -249,9 +249,7 @@
SDL_Timer *timer;
SDL_TimerMap *entry;
- if (data->active) {
- data->active = SDL_FALSE;
-
+ if (SDL_AtomicCAS(&data->active, 1, 0)) { /* active? Move to inactive. */
/* Shutdown the timer thread */
if (data->thread) {
SDL_SemPost(data->sem);
@@ -291,21 +289,14 @@
SDL_Timer *timer;
SDL_TimerMap *entry;
- if (!data->active) {
- int status = 0;
-
- SDL_AtomicLock(&data->lock);
- if (!data->active) {
- status = SDL_TimerInit();
- }
- SDL_AtomicUnlock(&data->lock);
-
- if (status < 0) {
+ SDL_AtomicLock(&data->lock);
+ if (!SDL_AtomicGet(&data->active)) {
+ if (SDL_TimerInit() < 0) {
+ SDL_AtomicUnlock(&data->lock);
return 0;
}
}
- SDL_AtomicLock(&data->lock);
timer = data->freelist;
if (timer) {
data->freelist = timer->next;
@@ -326,7 +317,7 @@
timer->param = param;
timer->interval = interval;
timer->scheduled = SDL_GetTicks() + interval;
- timer->canceled = SDL_FALSE;
+ SDL_AtomicSet(&timer->canceled, 0);
entry = (SDL_TimerMap *)SDL_malloc(sizeof(*entry));
if (!entry) {
@@ -377,8 +368,8 @@
SDL_UnlockMutex(data->timermap_lock);
if (entry) {
- if (!entry->timer->canceled) {
- entry->timer->canceled = SDL_TRUE;
+ if (!SDL_AtomicGet(&entry->timer->canceled)) {
+ SDL_AtomicSet(&entry->timer->canceled, 1);
canceled = SDL_TRUE;
}
SDL_free(entry);
--- a/src/video/android/SDL_androidtouch.c Sat Jan 02 12:17:33 2016 -0800
+++ b/src/video/android/SDL_androidtouch.c Sun Jan 03 06:50:50 2016 -0500
@@ -50,7 +50,7 @@
*window_y = (int)(y * window_h);
}
-static volatile SDL_bool separate_mouse_and_touch = SDL_FALSE;
+static SDL_bool separate_mouse_and_touch = SDL_FALSE;
static void
SeparateEventsHintWatcher(void *userdata, const char *name,
--- a/test/testatomic.c Sat Jan 02 12:17:33 2016 -0800
+++ b/test/testatomic.c Sun Jan 03 06:50:50 2016 -0500
@@ -284,7 +284,7 @@
char cache_pad4[SDL_CACHELINE_SIZE-sizeof(SDL_SpinLock)-2*sizeof(SDL_atomic_t)];
#endif
- volatile SDL_bool active;
+ SDL_atomic_t active;
/* Only needed for the mutex test */
SDL_mutex *mutex;
@@ -305,7 +305,7 @@
SDL_AtomicSet(&queue->rwcount, 0);
SDL_AtomicSet(&queue->watcher, 0);
#endif
- queue->active = SDL_TRUE;
+ SDL_AtomicSet(&queue->active, 1);
}
static SDL_bool EnqueueEvent_LockFree(SDL_EventQueue *queue, const SDL_Event *event)
@@ -538,7 +538,7 @@
if (DequeueEvent_LockFree(queue, &event)) {
WriterData *writer = (WriterData*)event.user.data1;
++data->counters[writer->index];
- } else if (queue->active) {
+ } else if (SDL_AtomicGet(&queue->active)) {
++data->waits;
SDL_Delay(0);
} else {
@@ -551,7 +551,7 @@
if (DequeueEvent_Mutex(queue, &event)) {
WriterData *writer = (WriterData*)event.user.data1;
++data->counters[writer->index];
- } else if (queue->active) {
+ } else if (SDL_AtomicGet(&queue->active)) {
++data->waits;
SDL_Delay(0);
} else {
@@ -571,7 +571,7 @@
{
SDL_EventQueue *queue = (SDL_EventQueue *)_data;
- while (queue->active) {
+ while (SDL_AtomicGet(&queue->active)) {
SDL_AtomicLock(&queue->lock);
SDL_AtomicIncRef(&queue->watcher);
while (SDL_AtomicGet(&queue->rwcount) > 0) {
@@ -652,7 +652,7 @@
}
/* Shut down the queue so readers exit */
- queue.active = SDL_FALSE;
+ SDL_AtomicSet(&queue.active, 0);
/* Wait for the readers */
while (SDL_AtomicGet(&readersRunning) > 0) {
--- a/test/testlock.c Sat Jan 02 12:17:33 2016 -0800
+++ b/test/testlock.c Sun Jan 03 06:50:50 2016 -0500
@@ -23,7 +23,7 @@
static SDL_mutex *mutex = NULL;
static SDL_threadID mainthread;
static SDL_Thread *threads[6];
-static volatile int doterminate = 0;
+static SDL_atomic_t doterminate;
/*
* SDL_Quit() shouldn't be used with atexit() directly because
@@ -45,7 +45,7 @@
terminate(int sig)
{
signal(SIGINT, terminate);
- doterminate = 1;
+ SDL_AtomicSet(&doterminate, 1);
}
void
@@ -54,7 +54,7 @@
SDL_threadID id = SDL_ThreadID();
int i;
SDL_Log("Process %lu: Cleaning up...\n", id == mainthread ? 0 : id);
- doterminate = 1;
+ SDL_AtomicSet(&doterminate, 1);
for (i = 0; i < 6; ++i)
SDL_WaitThread(threads[i], NULL);
SDL_DestroyMutex(mutex);
@@ -66,7 +66,7 @@
{
if (SDL_ThreadID() == mainthread)
signal(SIGTERM, closemutex);
- while (!doterminate) {
+ while (!SDL_AtomicGet(&doterminate)) {
SDL_Log("Process %lu ready to work\n", SDL_ThreadID());
if (SDL_LockMutex(mutex) < 0) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't lock mutex: %s", SDL_GetError());
@@ -82,7 +82,7 @@
/* If this sleep isn't done, then threads may starve */
SDL_Delay(10);
}
- if (SDL_ThreadID() == mainthread && doterminate) {
+ if (SDL_ThreadID() == mainthread && SDL_AtomicGet(&doterminate)) {
SDL_Log("Process %lu: raising SIGTERM\n", SDL_ThreadID());
raise(SIGTERM);
}
@@ -105,6 +105,8 @@
}
atexit(SDL_Quit_Wrapper);
+ SDL_AtomicSet(&doterminate, 0);
+
if ((mutex = SDL_CreateMutex()) == NULL) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't create mutex: %s\n", SDL_GetError());
exit(1);
--- a/test/testmultiaudio.c Sat Jan 02 12:17:33 2016 -0800
+++ b/test/testmultiaudio.c Sun Jan 03 06:50:50 2016 -0500
@@ -25,7 +25,7 @@
{
SDL_AudioDeviceID dev;
int soundpos;
- volatile int done;
+ SDL_atomic_t done;
} callback_data;
callback_data cbd[64];
@@ -46,14 +46,14 @@
if (len > 0) {
stream += cpy;
SDL_memset(stream, spec.silence, len);
- cbd->done++;
+ SDL_AtomicSet(&cbd->done, 1);
}
}
void
loop()
{
- if(cbd[0].done) {
+ if (SDL_AtomicGet(&cbd[0].done)) {
#ifdef __EMSCRIPTEN__
emscripten_cancel_main_loop();
#endif
@@ -100,8 +100,7 @@
#ifdef __EMSCRIPTEN__
emscripten_set_main_loop(loop, 0, 1);
#else
- while (!cbd[0].done)
- {
+ while (!SDL_AtomicGet(&cbd[0].done)) {
#ifdef __ANDROID__
/* Empty queue, some application events would prevent pause. */
while (SDL_PollEvent(&event)){}
@@ -136,7 +135,7 @@
while (keep_going) {
keep_going = 0;
for (i = 0; i < devcount; i++) {
- if ((cbd[i].dev) && (!cbd[i].done)) {
+ if ((cbd[i].dev) && (!SDL_AtomicGet(&cbd[i].done))) {
keep_going = 1;
}
}
--- a/test/torturethread.c Sat Jan 02 12:17:33 2016 -0800
+++ b/test/torturethread.c Sun Jan 03 06:50:50 2016 -0500
@@ -21,7 +21,7 @@
#define NUMTHREADS 10
-static char volatile time_for_threads_to_die[NUMTHREADS];
+static SDL_atomic_t time_for_threads_to_die[NUMTHREADS];
/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
@@ -58,7 +58,7 @@
}
SDL_Log("Thread '%d' waiting for signal\n", tid);
- while (time_for_threads_to_die[tid] != 1) {
+ while (SDL_AtomicGet(&time_for_threads_to_die[tid]) != 1) {
; /* do nothing */
}
@@ -92,7 +92,7 @@
for (i = 0; i < NUMTHREADS; i++) {
char name[64];
SDL_snprintf(name, sizeof (name), "Parent%d", i);
- time_for_threads_to_die[i] = 0;
+ SDL_AtomicSet(&time_for_threads_to_die[i], 0);
threads[i] = SDL_CreateThread(ThreadFunc, name, (void*) (uintptr_t) i);
if (threads[i] == NULL) {
@@ -102,7 +102,7 @@
}
for (i = 0; i < NUMTHREADS; i++) {
- time_for_threads_to_die[i] = 1;
+ SDL_AtomicSet(&time_for_threads_to_die[i], 1);
}
for (i = 0; i < NUMTHREADS; i++) {