Question

I have a log system that collects messages in different queues. Also, the system accepts listeners (references to listeners) that system calls to write messages (listeners = consumers). Also, note that the whole log system is a singleton.

My problem is into destructor. You could send messages to different queues, and you can suscribe a listener to listen more than one queue, so every message queue could have a list of listeners. When destructor is called, if a listener is added to two or more queues, destructor try to delete the same listener 2 times (or more).

A dirty solution is to do not delete the listeners (there are few and little and is a singleton, so the leak is little, but I don’t like).
Another solution is to maintain another structure to hold all listeners, and delete pointers from this structure instead from the queues. But nothing grants me that two different pointers points to the same listener and the problem would be the same.

I think I need a different solution. Some ideas?

Thanks!!!!

Answer 1

Why don’t you just use shared_pointers? They come along with the Boost library (I don’t know if they were included in the lastest C++ standard) and it looks that they are exactly what you need.

The shared_ptr class template stores a pointer to a dynamically allocated object, typically with a C++ new-expression. The object pointed to is guaranteed to be deleted when the last shared_ptr pointing to it is destroyed or reset.

See http://www.boost.org/doc/libs/1_48_0/libs/smart_ptr/shared_ptr.htm for more informations.