Reimplement Mutex with C++'s <mutex>

Main:
- It's now implemented thanks to `<mutex>`. No more platform-specific implementations.
- `BinaryMutex` (non-recursive) is added, as an alternative for special cases.
- Doesn't need allocation/deallocation anymore. It can live in the stack and be part of other classes.
- Because of that, it's methods are now `const` and the inner mutex is `mutable` so it can be easily used in `const` contexts.
- A no-op implementation is provided if `NO_THREADS` is defined. No more need to add `#ifdef NO_THREADS` just for this.
- `MutexLock` now takes a reference. At this point the cases of null `Mutex`es are rare. If you ever need that, just don't use `MutexLock`.
- Thread-safe utilities are therefore simpler now.

Misc.:
- `ScopedMutexLock` is dropped and replaced by `MutexLock`, because they were pretty much the same.
- Every case of lock, do-something, unlock is replaced by `MutexLock` (complex cases where it's not straightfoward are kept as as explicit lock and unlock).
- `ShaderRD` contained an `std::mutex`, which has been replaced by `Mutex`.

2 files changed, 0 insertions, 164 deletions

diff --git a/drivers/windows/mutex_windows.cpp b/drivers/windows/mutex_windows.cpp
deleted file mode 100644
index 1f14adb48f..0000000000
--- a/drivers/windows/mutex_windows.cpp
+++ /dev/null
@@ -1,101 +0,0 @@
-/*************************************************************************/
-/*  mutex_windows.cpp                                                    */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
-/*                                                                       */
-/* Permission is hereby granted, free of charge, to any person obtaining */
-/* a copy of this software and associated documentation files (the       */
-/* "Software"), to deal in the Software without restriction, including   */
-/* without limitation the rights to use, copy, modify, merge, publish,   */
-/* distribute, sublicense, and/or sell copies of the Software, and to    */
-/* permit persons to whom the Software is furnished to do so, subject to */
-/* the following conditions:                                             */
-/*                                                                       */
-/* The above copyright notice and this permission notice shall be        */
-/* included in all copies or substantial portions of the Software.       */
-/*                                                                       */
-/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
-/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
-/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
-/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
-/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
-/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
-/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
-/*************************************************************************/
-
-#include "mutex_windows.h"
-
-#include "core/os/memory.h"
-
-#ifdef WINDOWS_ENABLED
-
-void MutexWindows::lock() {
-
-#ifdef WINDOWS_USE_MUTEX
-	WaitForSingleObject(mutex, INFINITE);
-#else
-	EnterCriticalSection(&mutex);
-#endif
-}
-
-void MutexWindows::unlock() {
-
-#ifdef WINDOWS_USE_MUTEX
-	ReleaseMutex(mutex);
-#else
-	LeaveCriticalSection(&mutex);
-#endif
-}
-
-Error MutexWindows::try_lock() {
-
-#ifdef WINDOWS_USE_MUTEX
-	return (WaitForSingleObject(mutex, 0) == WAIT_TIMEOUT) ? ERR_BUSY : OK;
-#else
-
-	if (TryEnterCriticalSection(&mutex))
-		return OK;
-	else
-		return ERR_BUSY;
-#endif
-}
-
-Mutex *MutexWindows::create_func_windows(bool p_recursive) {
-
-	return memnew(MutexWindows);
-}
-
-void MutexWindows::make_default() {
-
-	create_func = create_func_windows;
-}
-
-MutexWindows::MutexWindows() {
-
-#ifdef WINDOWS_USE_MUTEX
-	mutex = CreateMutex(NULL, FALSE, NULL);
-#else
-#ifdef UWP_ENABLED
-	InitializeCriticalSectionEx(&mutex, 0, 0);
-#else
-	InitializeCriticalSection(&mutex);
-#endif
-#endif
-}
-
-MutexWindows::~MutexWindows() {
-
-#ifdef WINDOWS_USE_MUTEX
-	CloseHandle(mutex);
-#else
-
-	DeleteCriticalSection(&mutex);
-#endif
-}
-
-#endif
diff --git a/drivers/windows/mutex_windows.h b/drivers/windows/mutex_windows.h
deleted file mode 100644
index 28b97540b7..0000000000
--- a/drivers/windows/mutex_windows.h
+++ /dev/null
@@ -1,63 +0,0 @@
-/*************************************************************************/
-/*  mutex_windows.h                                                      */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
-/*                                                                       */
-/* Permission is hereby granted, free of charge, to any person obtaining */
-/* a copy of this software and associated documentation files (the       */
-/* "Software"), to deal in the Software without restriction, including   */
-/* without limitation the rights to use, copy, modify, merge, publish,   */
-/* distribute, sublicense, and/or sell copies of the Software, and to    */
-/* permit persons to whom the Software is furnished to do so, subject to */
-/* the following conditions:                                             */
-/*                                                                       */
-/* The above copyright notice and this permission notice shall be        */
-/* included in all copies or substantial portions of the Software.       */
-/*                                                                       */
-/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
-/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
-/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
-/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
-/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
-/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
-/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
-/*************************************************************************/
-
-#ifndef MUTEX_WINDOWS_H
-#define MUTEX_WINDOWS_H
-
-#ifdef WINDOWS_ENABLED
-
-#include "core/os/mutex.h"
-
-#include <windows.h>
-
-class MutexWindows : public Mutex {
-
-#ifdef WINDOWS_USE_MUTEX
-	HANDLE mutex;
-#else
-	CRITICAL_SECTION mutex;
-#endif
-
-	static Mutex *create_func_windows(bool p_recursive);
-
-public:
-	virtual void lock();
-	virtual void unlock();
-	virtual Error try_lock();
-
-	static void make_default();
-
-	MutexWindows();
-	~MutexWindows();
-};
-
-#endif
-
-#endif