.

attic/LockingPtr.hpp

@@ -0,0 +1,99 @@
+/*
+ * ZeroTier One - Network Virtualization Everywhere
+ * Copyright (C) 2011-2016  ZeroTier, Inc.  https://www.zerotier.com/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef ZT_LOCKINGPTR_HPP
+#define ZT_LOCKINGPTR_HPP
+
+#include "Mutex.hpp"
+
+namespace ZeroTier {
+
+/**
+ * A simple pointer that locks and holds a mutex until destroyed
+ *
+ * Care must be taken when using this. It's not very sophisticated and does
+ * not handle being copied except for the simple return use case. When it is
+ * copied it hands off the mutex to the copy and clears it in the original,
+ * meaning that the mutex is unlocked when the last LockingPtr<> in a chain
+ * of such handoffs is destroyed. If this chain of handoffs "forks" (more than
+ * one copy is made) then non-determinism may ensue.
+ *
+ * This does not delete or do anything else with the pointer. It also does not
+ * take care of locking the lock. That must be done beforehand.
+ */
+template<typename T>
+class LockingPtr
+{
+public:
+	LockingPtr() :
+		_ptr((T *)0),
+		_lock((Mutex *)0)
+	{
+	}
+
+	LockingPtr(T *obj,Mutex *lock) :
+		_ptr(obj),
+		_lock(lock)
+	{
+	}
+
+	LockingPtr(const LockingPtr &p) :
+		_ptr(p._ptr),
+		_lock(p._lock)
+	{
+		const_cast<LockingPtr *>(&p)->_lock = (Mutex *)0;
+	}
+
+	~LockingPtr()
+	{
+		if (_lock)
+			_lock->unlock();
+	}
+
+	inline LockingPtr &operator=(const LockingPtr &p)
+	{
+		_ptr = p._ptr;
+		_lock = p._lock;
+		const_cast<LockingPtr *>(&p)->_lock = (Mutex *)0;
+		return *this;
+	}
+
+	inline operator bool() const throw() { return (_ptr != (T *)0); }
+	inline T &operator*() const throw() { return *_ptr; }
+	inline T *operator->() const throw() { return _ptr; }
+
+	/**
+	 * @return Raw pointer to held object
+	 */
+	inline T *ptr() const throw() { return _ptr; }
+
+	inline bool operator==(const LockingPtr &sp) const throw() { return (_ptr == sp._ptr); }
+	inline bool operator!=(const LockingPtr &sp) const throw() { return (_ptr != sp._ptr); }
+	inline bool operator>(const LockingPtr &sp) const throw() { return (_ptr > sp._ptr); }
+	inline bool operator<(const LockingPtr &sp) const throw() { return (_ptr < sp._ptr); }
+	inline bool operator>=(const LockingPtr &sp) const throw() { return (_ptr >= sp._ptr); }
+	inline bool operator<=(const LockingPtr &sp) const throw() { return (_ptr <= sp._ptr); }
+
+private:
+	T *_ptr;
+	Mutex *_lock;
+};
+
+} // namespace ZeroTier
+
+#endif