Merge commit 'dec0d4ec4153bf9fc2b78ae6c2df45b6ea8dde7a' as 'external/sdl/SDL'

external/sdl/SDL/src/thread/stdcpp/SDL_sysrwlock.cpp

@@ -0,0 +1,130 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#include <shared_mutex>
+#include <system_error>
+#include <Windows.h>
+
+struct SDL_RWLock
+{
+    std::shared_mutex cpp_mutex;
+    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;
+    } catch (std::system_error &ex) {
+        SDL_SetError("unable to create a C++ rwlock: code=%d; %s", ex.code(), ex.what());
+        return NULL;
+    } catch (std::bad_alloc &) {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+}
+
+/* Free the rwlock */
+extern "C" void SDL_DestroyRWLock(SDL_RWLock *rwlock)
+{
+    if (rwlock != NULL) {
+        delete rwlock;
+    }
+}
+
+/* Lock the rwlock */
+extern "C" int 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());
+    }
+}
+
+/* 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 */
+{
+    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());
+    }
+}
+
+/* TryLock the rwlock for reading */
+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;
+    }
+    return retval;
+}
+
+/* TryLock the rwlock for writing */
+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();
+    }
+    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 */
+{
+    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();
+    }
+    return 0;
+}
+