1 files changed, 84 insertions, 0 deletions
diff --git a/utils/intrusive_refcount.hpp b/utils/intrusive_refcount.hpp
new file mode 100755
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+++ b/utils/intrusive_refcount.hpp
@@ -0,0 +1,84 @@
+#ifndef GRAEHL__SHARED__INTRUSIVE_REFCOUNT_HPP
+#define GRAEHL__SHARED__INTRUSIVE_REFCOUNT_HPP
+
+#include <boost/intrusive_ptr.hpp>
+#include <boost/noncopyable.hpp>
+#include <boost/detail/atomic_count.hpp>
+#include <cassert>
+
+/** usage:
+    struct mine : public boost::instrusive_refcount<mine> {};
+
+    boost::intrusive_ptr<mine> p(new mine());
+*/
+
+namespace boost {
+// note: the free functions need to be in boost namespace, OR namespace of involved type.  this is the only way to do it.
+
+template <class T>
+class intrusive_refcount;
+
+template <class T>
+class atomic_intrusive_refcount;
+
+template<class T>
+void intrusive_ptr_add_ref(intrusive_refcount<T>* ptr)
+{
+    ++(ptr->refs);
+}
+
+template<class T>
+void intrusive_ptr_release(intrusive_refcount<T>* ptr)
+{
+    if (!--(ptr->refs)) delete static_cast<T*>(ptr);
+}
+
+
+//WARNING: only 2^32 (unsigned) refs allowed.  hope that's ok :)
+template<class T>
+class intrusive_refcount : boost::noncopyable
+{
+ protected:
+//    typedef intrusive_refcount<T> pointed_type;
+    friend void intrusive_ptr_add_ref<T>(intrusive_refcount<T>* ptr);
+    friend void intrusive_ptr_release<T>(intrusive_refcount<T>* ptr);
+//    friend class intrusive_ptr<T>;
+
+    intrusive_refcount(): refs(0) {}
+    ~intrusive_refcount() { assert(refs==0); }
+
+private:
+    unsigned refs;
+};
+
+
+template<class T>
+void intrusive_ptr_add_ref(atomic_intrusive_refcount<T>* ptr)
+{
+    ++(ptr->refs);
+}
+
+template<class T>
+void intrusive_ptr_release(atomic_intrusive_refcount<T>* ptr)
+{
+    if(!--(ptr->refs)) delete static_cast<T*>(ptr);
+}
+
+template<class T>
+class atomic_intrusive_refcount : boost::noncopyable
+{
+ protected:
+    friend void intrusive_ptr_add_ref<T>(atomic_intrusive_refcount<T>* ptr);
+    friend void intrusive_ptr_release<T>(atomic_intrusive_refcount<T>* ptr);
+
+    atomic_intrusive_refcount(): refs(0) {}
+    ~atomic_intrusive_refcount() { assert(refs==0); }
+
+private:
+    boost::detail::atomic_count refs;
+};
+
+}
+
+
+#endif