// Support for the boost::intrusive_ptr<ActivityImpl> datatype
friend XBT_PUBLIC void intrusive_ptr_add_ref(ActivityImpl* activity);
friend XBT_PUBLIC void intrusive_ptr_release(ActivityImpl* activity);
+ int get_refcount() { return refcount_; } // For debugging purpose
static xbt::signal<void(ActivityImpl const&)> on_suspended;
static xbt::signal<void(ActivityImpl const&)> on_resumed;