From 18fbdbb456c07a56b358bea2e392765fbcbb3283 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pedro=20J=2E=20Est=C3=A9banez?= <pedrojrulez@gmail.com>
Date: Wed, 26 Feb 2020 11:28:13 +0100
Subject: 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- `ShaderRD` contained an `std::mutex`, which has been replaced by `Mutex`.
---
 core/os/mutex.cpp | 32 +++++++++-----------------------
 1 file changed, 9 insertions(+), 23 deletions(-)

(limited to 'core/os/mutex.cpp')

diff --git a/core/os/mutex.cpp b/core/os/mutex.cpp
index f099b4319a..74c308f646 100644
--- a/core/os/mutex.cpp
+++ b/core/os/mutex.cpp
@@ -30,31 +30,17 @@
 
 #include "mutex.h"
 
-#include "core/error_macros.h"
-
-#include <stddef.h>
-
-Mutex *(*Mutex::create_func)(bool) = 0;
-
-Mutex *Mutex::create(bool p_recursive) {
-
-	ERR_FAIL_COND_V(!create_func, 0);
-
-	return create_func(p_recursive);
-}
-
-Mutex::~Mutex() {
-}
-
-Mutex *_global_mutex = NULL;
+static Mutex _global_mutex;
 
 void _global_lock() {
-
-	if (_global_mutex)
-		_global_mutex->lock();
+	_global_mutex.lock();
 }
-void _global_unlock() {
 
-	if (_global_mutex)
-		_global_mutex->unlock();
+void _global_unlock() {
+	_global_mutex.unlock();
 }
+
+template class MutexImpl<std::recursive_mutex>;
+template class MutexImpl<std::mutex>;
+template class MutexLock<MutexImpl<std::recursive_mutex> >;
+template class MutexLock<MutexImpl<std::mutex> >;
-- 
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