[cache_writeback] Coded, needs testing

base/unique_handle.h

@@ -0,0 +1,67 @@
+#ifndef BASE_UNIQUE_HANDLE_H
+#define BASE_UNIQUE_HANDLE_H
+
+#include <list>
+#include <memory>
+#include <unistd.h>
+
+//----------------------------------------------------------------
+
+namespace base {
+	template <typename T, T TNul = T()>
+	class unique_handle
+	{
+	public:
+		unique_handle(std::nullptr_t = nullptr)
+			: id_(TNul) {
+		}
+
+		unique_handle(T x)
+		: id_(x) {
+		}
+
+		explicit operator bool() const {
+			return id_ != TNul;
+		}
+
+		operator T&() {
+			return id_;
+		}
+
+		operator T() const {
+			return id_;
+		}
+
+		T *operator&() {
+			return &id_;
+		}
+
+		const T *operator&() const {
+			return &id_;
+		}
+
+		friend bool operator == (unique_handle a, unique_handle b) { return a.id_ == b.id_; }
+		friend bool operator != (unique_handle a, unique_handle b) { return a.id_ != b.id_; }
+		friend bool operator == (unique_handle a, std::nullptr_t) { return a.id_ == TNul; }
+		friend bool operator != (unique_handle a, std::nullptr_t) { return a.id_ != TNul; }
+		friend bool operator == (std::nullptr_t, unique_handle b) { return TNul == b.id_; }
+		friend bool operator != (std::nullptr_t, unique_handle b) { return TNul != b.id_; }
+
+	private:
+		T id_;
+	};
+
+	//--------------------------------
+
+	struct fd_deleter {
+		typedef unique_handle<int, -1> pointer;
+		void operator()(pointer p) {
+			::close(p);
+		}
+	};
+	typedef std::unique_ptr<int, fd_deleter> unique_fd;
+}
+
+//----------------------------------------------------------------
+
+#endif