Introduce SpinMutex

lib/base/atomic.hpp

@@ -41,6 +41,35 @@ class Atomic : public std::atomic<T> {
 	}
 };
 
+/**
+ * Classic spinlock mutex based on std::atomic_flag.
+ *
+ * @ingroup base
+ */
+class SpinMutex
+{
+public:
+	SpinMutex() = default;
+	SpinMutex(const SpinMutex&) = delete;
+	SpinMutex(SpinMutex&&) = delete;
+	SpinMutex& operator=(const SpinMutex&) = delete;
+	SpinMutex& operator=(SpinMutex&&) = delete;
+
+	void lock() noexcept
+	{
+		while (m_State.test_and_set(std::memory_order_acquire)) {
+		}
+	}
+
+	void unlock() noexcept
+	{
+		m_State.clear(std::memory_order_release);
+	}
+
+private:
+	std::atomic_flag m_State = ATOMIC_FLAG_INIT;
+};
+
 /**
  * Wraps any T into a std::atomic<T>-like interface that locks using a mutex.
  *