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thread: Locking mutexes and rwlocks are now void functions.

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Almost nothing checks these return values, and there's no reason a valid
lock should fail to operate. The cases where a lock isn't valid (it's a
bogus pointer, it was previously destroyed, a thread is unlocking a lock it
doesn't own, etc) are undefined behavior and always were, and should be
treated as an application bug.

Reference Issue #8096.
This commit is contained in:
Ryan C. Gordon 2023-10-25 10:00:26 -04:00
parent 082ef41566
commit 899eb0d042
21 changed files with 496 additions and 746 deletions
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90
src/thread/stdcpp/SDL_sysrwlock.cpp
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@ -30,10 +30,8 @@ struct SDL_RWLock
SDL_threadID write_owner;
};
/* Create a rwlock */
extern "C" SDL_RWLock *SDL_CreateRWLock(void)
{
/* Allocate and initialize the rwlock */
try {
SDL_RWLock *rwlock = new SDL_RWLock;
return rwlock;
@ -46,7 +44,6 @@ extern "C" SDL_RWLock *SDL_CreateRWLock(void)
}
}
/* Free the rwlock */
extern "C" void SDL_DestroyRWLock(SDL_RWLock *rwlock)
{
if (rwlock != NULL) {
@ -54,77 +51,64 @@ extern "C" void SDL_DestroyRWLock(SDL_RWLock *rwlock)
}
}
/* Lock the rwlock */
extern "C" int SDL_LockRWLockForReading(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
extern "C" void SDL_LockRWLockForReading(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
{
if (!rwlock) {
return SDL_InvalidParamError("rwlock");
}
try {
rwlock->cpp_mutex.lock_shared();
return 0;
} catch (std::system_error &ex) {
return SDL_SetError("unable to lock a C++ rwlock: code=%d; %s", ex.code(), ex.what());
if (rwlock) {
try {
rwlock->cpp_mutex.lock_shared();
} catch (std::system_error &ex) {
SDL_assert(!"Error trying to lock rwlock for reading"); // assume we're in a lot of trouble if this assert fails.
//return SDL_SetError("unable to lock a C++ rwlock: code=%d; %s", ex.code(), ex.what());
}
}
}
/* Lock the rwlock for writing */
extern "C" int SDL_LockRWLockForWriting(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
extern "C" void SDL_LockRWLockForWriting(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
{
if (!rwlock) {
return SDL_InvalidParamError("rwlock");
}
try {
rwlock->cpp_mutex.lock();
rwlock->write_owner = SDL_ThreadID();
return 0;
} catch (std::system_error &ex) {
return SDL_SetError("unable to lock a C++ rwlock: code=%d; %s", ex.code(), ex.what());
if (rwlock) {
try {
rwlock->cpp_mutex.lock();
rwlock->write_owner = SDL_ThreadID();
} catch (std::system_error &ex) {
SDL_assert(!"Error trying to lock rwlock for writing"); // assume we're in a lot of trouble if this assert fails.
//return SDL_SetError("unable to lock a C++ rwlock: code=%d; %s", ex.code(), ex.what());
}
}
}
/* TryLock the rwlock for reading */
int SDL_TryLockRWLockForReading(SDL_RWLock *rwlock)
extern "C" int SDL_TryLockRWLockForReading(SDL_RWLock *rwlock)
{
int retval = 0;
if (!rwlock) {
retval = SDL_InvalidParamError("rwlock");
} else if (rwlock->cpp_mutex.try_lock_shared() == false) {
retval = SDL_RWLOCK_TIMEDOUT;
if (rwlock) {
if (rwlock->cpp_mutex.try_lock_shared() == false) {
retval = SDL_RWLOCK_TIMEDOUT;
}
}
return retval;
}
/* TryLock the rwlock for writing */
int SDL_TryLockRWLockForWriting(SDL_RWLock *rwlock)
extern "C" int SDL_TryLockRWLockForWriting(SDL_RWLock *rwlock)
{
int retval = 0;
if (!rwlock) {
retval = SDL_InvalidParamError("rwlock");
} else if (rwlock->cpp_mutex.try_lock() == false) {
retval = SDL_RWLOCK_TIMEDOUT;
} else {
rwlock->write_owner = SDL_ThreadID();
if (rwlock) {
if (rwlock->cpp_mutex.try_lock() == false) {
retval = SDL_RWLOCK_TIMEDOUT;
} else {
rwlock->write_owner = SDL_ThreadID();
}
}
return retval;
}
/* Unlock the rwlock */
extern "C" int
SDL_UnlockRWLock(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS /* clang doesn't know about NULL mutexes */
extern "C" void SDL_UnlockRWLock(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
{
if (!rwlock) {
return SDL_InvalidParamError("rwlock");
} else if (rwlock->write_owner == SDL_ThreadID()) {
rwlock->write_owner = 0;
rwlock->cpp_mutex.unlock();
} else {
rwlock->cpp_mutex.unlock_shared();
if (rwlock) {
if (rwlock->write_owner == SDL_ThreadID()) {
rwlock->write_owner = 0;
rwlock->cpp_mutex.unlock();
} else {
rwlock->cpp_mutex.unlock_shared();
}
}
return 0;
}