3 files changed, 61 insertions, 41 deletions

diff --git a/core/os/condition_variable.h b/core/os/condition_variable.h
index fa1355e98c..c819fa6b40 100644
--- a/core/os/condition_variable.h
+++ b/core/os/condition_variable.h
@@ -32,6 +32,7 @@
 #define CONDITION_VARIABLE_H
 
 #include "core/os/mutex.h"
+#include "core/os/safe_binary_mutex.h"
 
 #ifdef THREADS_ENABLED
 
@@ -56,7 +57,12 @@ class ConditionVariable {
 public:
 	template <typename BinaryMutexT>
 	_ALWAYS_INLINE_ void wait(const MutexLock<BinaryMutexT> &p_lock) const {
-		condition.wait(const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(p_lock.lock));
+		condition.wait(const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(p_lock._get_lock()));
+	}
+
+	template <int Tag>
+	_ALWAYS_INLINE_ void wait(const MutexLock<SafeBinaryMutex<Tag>> &p_lock) const {
+		condition.wait(const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(p_lock.mutex._get_lock()));
 	}
 
 	_ALWAYS_INLINE_ void notify_one() const {
diff --git a/core/os/mutex.h b/core/os/mutex.h
index 3e7aa81bc1..773b31828d 100644
--- a/core/os/mutex.h
+++ b/core/os/mutex.h
@@ -72,13 +72,18 @@ public:
 
 template <typename MutexT>
 class MutexLock {
-	friend class ConditionVariable;
-
 	THREADING_NAMESPACE::unique_lock<typename MutexT::StdMutexType> lock;
 
 public:
 	explicit MutexLock(const MutexT &p_mutex) :
 			lock(p_mutex.mutex) {}
+
+	// Clarification: all the funny syntax is needed so this function exists only for binary mutexes.
+	template <typename T = MutexT>
+	_ALWAYS_INLINE_ THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &_get_lock(
+			typename std::enable_if<std::is_same<T, THREADING_NAMESPACE::mutex>::value> * = nullptr) const {
+		return const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(lock);
+	}
 };
 
 using Mutex = MutexImpl<THREADING_NAMESPACE::recursive_mutex>; // Recursive, for general use
diff --git a/core/os/safe_binary_mutex.h b/core/os/safe_binary_mutex.h
index 1e98cc074c..1035ee76b4 100644
--- a/core/os/safe_binary_mutex.h
+++ b/core/os/safe_binary_mutex.h
@@ -37,6 +37,11 @@
 
 #ifdef THREADS_ENABLED
 
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wundefined-var-template"
+#endif
+
 // A very special kind of mutex, used in scenarios where these
 // requirements hold at the same time:
 // - Must be used with a condition variable (only binary mutexes are suitable).
@@ -47,76 +52,80 @@
 // Also, don't forget to declare the thread_local variable on each use.
 template <int Tag>
 class SafeBinaryMutex {
-	friend class MutexLock<SafeBinaryMutex>;
+	friend class MutexLock<SafeBinaryMutex<Tag>>;
 
 	using StdMutexType = THREADING_NAMESPACE::mutex;
 
 	mutable THREADING_NAMESPACE::mutex mutex;
-	static thread_local uint32_t count;
+
+	struct TLSData {
+		mutable THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> lock;
+		uint32_t count = 0;
+
+		TLSData(SafeBinaryMutex<Tag> &p_mutex) :
+				lock(p_mutex.mutex, THREADING_NAMESPACE::defer_lock) {}
+	};
+	static thread_local TLSData tls_data;
 
 public:
 	_ALWAYS_INLINE_ void lock() const {
-		if (++count == 1) {
-			mutex.lock();
+		if (++tls_data.count == 1) {
+			tls_data.lock.lock();
 		}
 	}
 
 	_ALWAYS_INLINE_ void unlock() const {
-		DEV_ASSERT(count);
-		if (--count == 0) {
-			mutex.unlock();
+		DEV_ASSERT(tls_data.count);
+		if (--tls_data.count == 0) {
+			tls_data.lock.unlock();
 		}
 	}
 
-	_ALWAYS_INLINE_ bool try_lock() const {
-		if (count) {
-			count++;
-			return true;
-		} else {
-			if (mutex.try_lock()) {
-				count++;
-				return true;
-			} else {
-				return false;
-			}
-		}
+	_ALWAYS_INLINE_ THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &_get_lock() const {
+		return const_cast<THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> &>(tls_data.lock);
 	}
 
-	~SafeBinaryMutex() {
-		DEV_ASSERT(!count);
+	_ALWAYS_INLINE_ SafeBinaryMutex() {
+	}
+
+	_ALWAYS_INLINE_ ~SafeBinaryMutex() {
+		DEV_ASSERT(!tls_data.count);
 	}
 };
 
-// This specialization is needed so manual locking and MutexLock can be used
-// at the same time on a SafeBinaryMutex.
 template <int Tag>
 class MutexLock<SafeBinaryMutex<Tag>> {
 	friend class ConditionVariable;
 
-	THREADING_NAMESPACE::unique_lock<THREADING_NAMESPACE::mutex> lock;
+	const SafeBinaryMutex<Tag> &mutex;
 
 public:
-	_ALWAYS_INLINE_ explicit MutexLock(const SafeBinaryMutex<Tag> &p_mutex) :
-			lock(p_mutex.mutex) {
-		SafeBinaryMutex<Tag>::count++;
-	};
-	_ALWAYS_INLINE_ ~MutexLock() {
-		SafeBinaryMutex<Tag>::count--;
-	};
+	explicit MutexLock(const SafeBinaryMutex<Tag> &p_mutex) :
+			mutex(p_mutex) {
+		mutex.lock();
+	}
+
+	~MutexLock() {
+		mutex.unlock();
+	}
 };
 
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
 #else // No threads.
 
 template <int Tag>
-class SafeBinaryMutex : public MutexImpl {
-	static thread_local uint32_t count;
-};
+class SafeBinaryMutex {
+	struct TLSData {
+		TLSData(SafeBinaryMutex<Tag> &p_mutex) {}
+	};
+	static thread_local TLSData tls_data;
 
-template <int Tag>
-class MutexLock<SafeBinaryMutex<Tag>> {
 public:
-	MutexLock(const SafeBinaryMutex<Tag> &p_mutex) {}
-	~MutexLock() {}
+	void lock() const {}
+	void unlock() const {}
 };
 
 #endif // THREADS_ENABLED