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Remove almost all instances of "volatile" keyword.

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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.
This commit is contained in:
Ryan C. Gordon 2016-01-03 06:50:50 -05:00
parent 21f66ea295
commit fa8c83c1c1
11 changed files with 66 additions and 72 deletions
Download patch file Download diff file Expand all files Collapse all files

2
src/haptic/windows/SDL_windowshaptic.c
View file

@ -255,7 +255,7 @@ SDL_SYS_HapticQuit(void)
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;
}

4
src/haptic/windows/SDL_windowshaptic_c.h
View file

@ -42,8 +42,8 @@ struct haptic_hwdata
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;
};

4
src/haptic/windows/SDL_xinputhaptic.c
View file

@ -146,7 +146,7 @@ SDL_RunXInputHaptic(void *arg)
{
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 @@ SDL_XINPUT_HapticOpenFromJoystick(SDL_Haptic * haptic, SDL_Joystick * joystick)
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);
}