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899eb0d042
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.
115 lines
3.5 KiB
C++
115 lines
3.5 KiB
C++
/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "SDL_internal.h"
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#include <shared_mutex>
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#include <system_error>
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#include <Windows.h>
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struct SDL_RWLock
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{
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std::shared_mutex cpp_mutex;
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SDL_threadID write_owner;
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};
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extern "C" SDL_RWLock *SDL_CreateRWLock(void)
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{
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try {
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SDL_RWLock *rwlock = new SDL_RWLock;
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return rwlock;
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} catch (std::system_error &ex) {
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SDL_SetError("unable to create a C++ rwlock: code=%d; %s", ex.code(), ex.what());
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return NULL;
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} catch (std::bad_alloc &) {
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SDL_OutOfMemory();
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return NULL;
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}
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}
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extern "C" void SDL_DestroyRWLock(SDL_RWLock *rwlock)
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{
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if (rwlock != NULL) {
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delete rwlock;
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}
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}
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extern "C" void SDL_LockRWLockForReading(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
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{
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if (rwlock) {
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try {
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rwlock->cpp_mutex.lock_shared();
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} catch (std::system_error &ex) {
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SDL_assert(!"Error trying to lock rwlock for reading"); // assume we're in a lot of trouble if this assert fails.
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//return SDL_SetError("unable to lock a C++ rwlock: code=%d; %s", ex.code(), ex.what());
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}
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}
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}
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extern "C" void SDL_LockRWLockForWriting(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
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{
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if (rwlock) {
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try {
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rwlock->cpp_mutex.lock();
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rwlock->write_owner = SDL_ThreadID();
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} catch (std::system_error &ex) {
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SDL_assert(!"Error trying to lock rwlock for writing"); // assume we're in a lot of trouble if this assert fails.
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//return SDL_SetError("unable to lock a C++ rwlock: code=%d; %s", ex.code(), ex.what());
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}
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}
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}
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extern "C" int SDL_TryLockRWLockForReading(SDL_RWLock *rwlock)
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{
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int retval = 0;
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if (rwlock) {
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if (rwlock->cpp_mutex.try_lock_shared() == false) {
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retval = SDL_RWLOCK_TIMEDOUT;
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}
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}
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return retval;
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}
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extern "C" int SDL_TryLockRWLockForWriting(SDL_RWLock *rwlock)
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{
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int retval = 0;
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if (rwlock) {
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if (rwlock->cpp_mutex.try_lock() == false) {
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retval = SDL_RWLOCK_TIMEDOUT;
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} else {
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rwlock->write_owner = SDL_ThreadID();
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}
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}
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return retval;
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}
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extern "C" void SDL_UnlockRWLock(SDL_RWLock *rwlock) SDL_NO_THREAD_SAFETY_ANALYSIS // clang doesn't know about NULL mutexes
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{
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if (rwlock) {
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if (rwlock->write_owner == SDL_ThreadID()) {
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rwlock->write_owner = 0;
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rwlock->cpp_mutex.unlock();
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} else {
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rwlock->cpp_mutex.unlock_shared();
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}
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}
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}
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