Implement "weak pointer" behavior on Topology Path canonicalization hash table.

node/AtomicCounter.hpp

@@ -20,11 +20,9 @@
 #define ZT_ATOMICCOUNTER_HPP
 
 #include "Constants.hpp"
-#include "Mutex.hpp"
 #include "NonCopyable.hpp"
 
-#ifdef __WINDOWS__
+#ifndef __GNUC__
-// <atomic> will replace this whole class eventually once it's ubiquitous
 #include <atomic>
 #endif
 
@@ -36,75 +34,34 @@ namespace ZeroTier {
 class AtomicCounter : NonCopyable
 {
 public:
-	/**
-	 * Initialize counter at zero
-	 */
 	AtomicCounter()
-		throw()
 	{
 		_v = 0;
 	}
 
-	inline operator int() const
-		throw()
-	{
-#ifdef __GNUC__
-		return __sync_or_and_fetch(const_cast <volatile int *>(&_v),0);
-#else
-#ifdef __WINDOWS__
-		return (int)_v;
-#else
-		_l.lock();
-		int v = _v;
-		_l.unlock();
-		return v;
-#endif
-#endif
-	}
-
 	inline int operator++()
-		throw()
 	{
 #ifdef __GNUC__
 		return __sync_add_and_fetch(&_v,1);
 #else
-#ifdef __WINDOWS__
 		return ++_v;
-#else
-		_l.lock();
-		int v = ++_v;
-		_l.unlock();
-		return v;
-#endif
 #endif
 	}
 
 	inline int operator--()
-		throw()
 	{
 #ifdef __GNUC__
 		return __sync_sub_and_fetch(&_v,1);
 #else
-#ifdef __WINDOWS__
 		return --_v;
-#else
-		_l.lock();
-		int v = --_v;
-		_l.unlock();
-		return v;
-#endif
 #endif
 	}
 
 private:
-#ifdef __WINDOWS__
+#ifdef __GNUC__
-	std::atomic_int _v;
-#else
 	int _v;
-#ifndef __GNUC__
+#else
-#warning Neither __WINDOWS__ nor __GNUC__ so AtomicCounter using Mutex
+	std::atomic_int _v;
-	Mutex _l;
-#endif
 #endif
 };
 

node/SharedPtr.hpp

@@ -119,16 +119,40 @@ public:
 	inline T *ptr() const throw() { return _ptr; }
 
 	/**
-	 * Set this pointer to null
+	 * Set this pointer to NULL
 	 */
 	inline void zero()
 	{
 		if (_ptr) {
 			if (--_ptr->__refCount <= 0)
 				delete _ptr;
-		}
 			_ptr = (T *)0;
 		}
+	}
+
+	/**
+	 * Set this pointer to NULL if this is the only pointer holding the object
+	 *
+	 * @return True if object was deleted and SharedPtr is now NULL (or was already NULL)
+	 */
+	inline bool reclaimIfWeak()
+	{
+		if (_ptr) {
+			if (++_ptr->__refCount <= 2) {
+				if (--_ptr->__refCount <= 1) {
+					delete _ptr;
+					_ptr = (T *)0;
+					return true;
+				} else {
+					return false;
+				}
+			} else {
+				return false;
+			}
+		} else {
+			return true;
+		}
+	}
 
 	inline bool operator==(const SharedPtr &sp) const throw() { return (_ptr == sp._ptr); }
 	inline bool operator!=(const SharedPtr &sp) const throw() { return (_ptr != sp._ptr); }

node/Topology.cpp

@@ -251,6 +251,7 @@ bool Topology::worldUpdateIfValid(const World &newWorld)
 void Topology::clean(uint64_t now)
 {
 	Mutex::Lock _l(_lock);
+	{
 		Hashtable< Address,SharedPtr<Peer> >::Iterator i(_peers);
 		Address *a = (Address *)0;
 		SharedPtr<Peer> *p = (SharedPtr<Peer> *)0;
@@ -262,6 +263,16 @@ void Topology::clean(uint64_t now)
 			}
 		}
 	}
+	{
+		Hashtable< Path::HashKey,SharedPtr<Path> >::Iterator i(_paths);
+		Path::HashKey *k = (Path::HashKey *)0;
+		SharedPtr<Path> *p = (SharedPtr<Path> *)0;
+		while (i.next(k,p)) {
+			if (p->reclaimIfWeak())
+				_paths.erase(*k);
+		}
+	}
+}
 
 Identity Topology::_getIdentity(const Address &zta)
 {