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rwlock: Make generic implmentations work on single-threaded platforms.

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Fixes #8101.
This commit is contained in:
Ryan C. Gordon
2023-08-11 15:02:52 -04:00
parent 80850af7ce
commit b75c751dfc
1 changed files with 21 additions and 1 deletions
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22
src/thread/generic/SDL_sysrwlock.c
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@@ -43,22 +43,27 @@
struct SDL_RWLock struct SDL_RWLock
{ {
#ifdef SDL_THREADS_DISABLED
int unused;
#else
SDL_Mutex *lock; SDL_Mutex *lock;
SDL_Condition *condition; SDL_Condition *condition;
SDL_threadID writer_thread; SDL_threadID writer_thread;
SDL_AtomicInt reader_count; SDL_AtomicInt reader_count;
SDL_AtomicInt writer_count; SDL_AtomicInt writer_count;
#endif
}; };
SDL_RWLock *SDL_CreateRWLock_generic(void) SDL_RWLock *SDL_CreateRWLock_generic(void)
{ {
SDL_RWLock *rwlock = (SDL_RWLock *) SDL_malloc(sizeof (*rwlock)); SDL_RWLock *rwlock = (SDL_RWLock *) SDL_calloc(1, sizeof (*rwlock));
if (!rwlock) { if (!rwlock) {
SDL_OutOfMemory(); SDL_OutOfMemory();
return NULL; return NULL;
} }
#ifndef SDL_THREADS_DISABLED
rwlock->lock = SDL_CreateMutex(); rwlock->lock = SDL_CreateMutex();
if (!rwlock->lock) { if (!rwlock->lock) {
SDL_free(rwlock); SDL_free(rwlock);
@@ -74,6 +79,7 @@ SDL_RWLock *SDL_CreateRWLock_generic(void)
SDL_AtomicSet(&rwlock->reader_count, 0); SDL_AtomicSet(&rwlock->reader_count, 0);
SDL_AtomicSet(&rwlock->writer_count, 0); SDL_AtomicSet(&rwlock->writer_count, 0);
#endif
return rwlock; return rwlock;
} }
@@ -81,14 +87,17 @@ SDL_RWLock *SDL_CreateRWLock_generic(void)
void SDL_DestroyRWLock_generic(SDL_RWLock *rwlock) void SDL_DestroyRWLock_generic(SDL_RWLock *rwlock)
{ {
if (rwlock) { if (rwlock) {
#ifndef SDL_THREADS_DISABLED
SDL_DestroyMutex(rwlock->lock); SDL_DestroyMutex(rwlock->lock);
SDL_DestroyCondition(rwlock->condition); SDL_DestroyCondition(rwlock->condition);
#endif
SDL_free(rwlock); SDL_free(rwlock);
} }
} }
int SDL_LockRWLockForReading_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */ int SDL_LockRWLockForReading_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
{ {
#ifndef SDL_THREADS_DISABLED
if (!rwlock) { if (!rwlock) {
return SDL_InvalidParamError("rwlock"); return SDL_InvalidParamError("rwlock");
} else if (SDL_LockMutex(rwlock->lock) == -1) { } else if (SDL_LockMutex(rwlock->lock) == -1) {
@@ -99,11 +108,14 @@ int SDL_LockRWLockForReading_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_AN
SDL_AtomicAdd(&rwlock->reader_count, 1); SDL_AtomicAdd(&rwlock->reader_count, 1);
SDL_UnlockMutex(rwlock->lock); /* other readers can attempt to share the lock. */ SDL_UnlockMutex(rwlock->lock); /* other readers can attempt to share the lock. */
#endif
return 0; return 0;
} }
int SDL_LockRWLockForWriting_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */ int SDL_LockRWLockForWriting_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
{ {
#ifndef SDL_THREADS_DISABLED
if (!rwlock) { if (!rwlock) {
return SDL_InvalidParamError("rwlock"); return SDL_InvalidParamError("rwlock");
} else if (SDL_LockMutex(rwlock->lock) == -1) { } else if (SDL_LockMutex(rwlock->lock) == -1) {
@@ -116,12 +128,14 @@ int SDL_LockRWLockForWriting_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_AN
/* we hold the lock! */ /* we hold the lock! */
SDL_AtomicAdd(&rwlock->writer_count, 1); /* we let these be recursive, but the API doesn't require this. It _does_ trust you unlock correctly! */ SDL_AtomicAdd(&rwlock->writer_count, 1); /* we let these be recursive, but the API doesn't require this. It _does_ trust you unlock correctly! */
#endif
return 0; return 0;
} }
int SDL_TryLockRWLockForReading_generic(SDL_RWLock *rwlock) int SDL_TryLockRWLockForReading_generic(SDL_RWLock *rwlock)
{ {
#ifndef SDL_THREADS_DISABLED
int rc; int rc;
if (!rwlock) { if (!rwlock) {
@@ -138,11 +152,14 @@ int SDL_TryLockRWLockForReading_generic(SDL_RWLock *rwlock)
SDL_AtomicAdd(&rwlock->reader_count, 1); SDL_AtomicAdd(&rwlock->reader_count, 1);
SDL_UnlockMutex(rwlock->lock); /* other readers can attempt to share the lock. */ SDL_UnlockMutex(rwlock->lock); /* other readers can attempt to share the lock. */
#endif
return 0; return 0;
} }
int SDL_TryLockRWLockForWriting_generic(SDL_RWLock *rwlock) int SDL_TryLockRWLockForWriting_generic(SDL_RWLock *rwlock)
{ {
#ifndef SDL_THREADS_DISABLED
int rc; int rc;
if (!rwlock) { if (!rwlock) {
@@ -158,12 +175,14 @@ int SDL_TryLockRWLockForWriting_generic(SDL_RWLock *rwlock)
/* we hold the lock! */ /* we hold the lock! */
SDL_AtomicAdd(&rwlock->writer_count, 1); /* we let these be recursive, but the API doesn't require this. It _does_ trust you unlock correctly! */ SDL_AtomicAdd(&rwlock->writer_count, 1); /* we let these be recursive, but the API doesn't require this. It _does_ trust you unlock correctly! */
#endif
return 0; return 0;
} }
int SDL_UnlockRWLock_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */ int SDL_UnlockRWLock_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
{ {
#ifndef SDL_THREADS_DISABLED
if (!rwlock) { if (!rwlock) {
return SDL_InvalidParamError("rwlock"); return SDL_InvalidParamError("rwlock");
} }
@@ -179,6 +198,7 @@ int SDL_UnlockRWLock_generic(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /
} }
SDL_UnlockMutex(rwlock->lock); SDL_UnlockMutex(rwlock->lock);
#endif
return 0; return 0;
} }