Adding upstream version 2.14.2.upstream/2.14.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 91 insertions, 0 deletions

diff --git a/lib/base/atomic.hpp b/lib/base/atomic.hpp
new file mode 100644
index 0000000..c8f169c
--- /dev/null
+++ b/lib/base/atomic.hpp
@@ -0,0 +1,91 @@
+/* Icinga 2 | (c) 2019 Icinga GmbH | GPLv2+ */
+
+#ifndef ATOMIC_H
+#define ATOMIC_H
+
+#include <atomic>
+#include <mutex>
+#include <type_traits>
+#include <utility>
+
+namespace icinga
+{
+
+/**
+ * Extends std::atomic with an atomic constructor.
+ *
+ * @ingroup base
+ */
+template<class T>
+class Atomic : public std::atomic<T> {
+public:
+	/**
+	 * Like std::atomic#atomic, but operates atomically
+	 *
+	 * @param desired Initial value
+	 */
+	inline Atomic(T desired)
+	{
+		this->store(desired);
+	}
+
+	/**
+	 * Like std::atomic#atomic, but operates atomically
+	 *
+	 * @param desired Initial value
+	 * @param order Initial store operation's memory order
+	 */
+	inline Atomic(T desired, std::memory_order order)
+	{
+		this->store(desired, order);
+	}
+};
+
+/**
+ * Wraps any T into a std::atomic<T>-like interface that locks using a mutex.
+ *
+ * In contrast to std::atomic<T>, Locked<T> is also valid for types that are not trivially copyable.
+ * In case T is trivially copyable, std::atomic<T> is almost certainly the better choice.
+ *
+ * @ingroup base
+ */
+template<typename T>
+class Locked
+{
+public:
+	inline T load() const
+	{
+		std::unique_lock<std::mutex> lock(m_Mutex);
+
+		return m_Value;
+	}
+
+	inline void store(T desired)
+	{
+		std::unique_lock<std::mutex> lock(m_Mutex);
+
+		m_Value = std::move(desired);
+	}
+
+private:
+	mutable std::mutex m_Mutex;
+	T m_Value;
+};
+
+/**
+ * Type alias for std::atomic<T> if possible, otherwise Locked<T> is used as a fallback.
+ *
+ * @ingroup base
+ */
+template <typename T>
+using AtomicOrLocked =
+#if defined(__GNUC__) && __GNUC__ < 5
+	// GCC does not implement std::is_trivially_copyable until version 5.
+	typename std::conditional<std::is_fundamental<T>::value || std::is_pointer<T>::value, std::atomic<T>, Locked<T>>::type;
+#else /* defined(__GNUC__) && __GNUC__ < 5 */
+	typename std::conditional<std::is_trivially_copyable<T>::value, std::atomic<T>, Locked<T>>::type;
+#endif /* defined(__GNUC__) && __GNUC__ < 5 */
+
+}
+
+#endif /* ATOMIC_H */