From af2750767440909def8c3373f8c9a6778d131829 Mon Sep 17 00:00:00 2001
From: Wenzel Jakob <wenzel@cs.cornell.edu>
Date: Mon, 1 Nov 2010 23:48:28 +0100
Subject: [PATCH] switched object reference counting to atomics

---
 include/mitsuba/core/object.h |  6 +++---
 src/libcore/object.cpp        | 31 +++++++------------------------
 2 files changed, 10 insertions(+), 27 deletions(-)

diff --git a/include/mitsuba/core/object.h b/include/mitsuba/core/object.h
index 9305942d..31f86620 100644
--- a/include/mitsuba/core/object.h
+++ b/include/mitsuba/core/object.h
@@ -73,10 +73,10 @@ protected:
 	 */
 	virtual ~Object();
 private:
-	mutable int m_refCount;
-#if defined(WIN32)
-	mutable CRITICAL_SECTION m_refLock;
+#if defined(_WIN32)
+	mutable LONG volatile m_refCount;
 #else
+	mutable int m_refCount;
 	mutable pthread_mutex_t m_refLock;
 #endif
 public:
diff --git a/src/libcore/object.cpp b/src/libcore/object.cpp
index 304611f6..7e29d752 100644
--- a/src/libcore/object.cpp
+++ b/src/libcore/object.cpp
@@ -24,40 +24,28 @@ Class *Object::m_theClass = new Class("Object", false, "");
 
 Object::Object()
  : m_refCount(0) {
-#if defined(WIN32)
-	InitializeCriticalSection(&m_refLock);
-#else
-	pthread_mutex_init(&m_refLock, NULL);
-#endif
 }
 
 void Object::incRef() const {
-#if defined(WIN32)
-	EnterCriticalSection(&m_refLock);
-	m_refCount++;
-	LeaveCriticalSection(&m_refLock);
+#if defined(_WIN32)
+	InterlockedIncrement(&m_refCount);
 #else
-	pthread_mutex_lock(&m_refLock);
-	m_refCount++;
-	pthread_mutex_unlock(&m_refLock);
+	__sync_fetch_and_add(&m_refCount, 1);
 #endif
 }
 
 void Object::decRef() const {
-#if defined(WIN32)
-	EnterCriticalSection(&m_refLock);
-	int count = --m_refCount;
-	LeaveCriticalSection(&m_refLock);
+#if defined(_WIN32)
+	int count = InterlockedDecrement(&m_refCount);
 #else
-	pthread_mutex_lock(&m_refLock);
-	int count = --m_refCount;
-	pthread_mutex_unlock(&m_refLock);
+	int count = __sync_sub_and_fetch(&m_refCount, 1);
 #endif
 	AssertEx(count >= 0, "Reference count is below zero!");
 	if (count == 0) 
 		delete this;
 }
 
+
 const Class *Object::getClass() const {
     return m_theClass;
 }
@@ -74,11 +62,6 @@ Object::~Object() {
 		Log(EWarn, "Deleting %s with reference count %i!", 
 			toString().c_str(), m_refCount);
 	}
-#if defined(WIN32)
-	DeleteCriticalSection(&m_refLock);
-#else
-	pthread_mutex_destroy(&m_refLock);
-#endif
 }
 
 MTS_NAMESPACE_END