[Openib-windows] RE: Reference count as a solution to the problemof an object life time

[Sean Hefty]

I want to give an example to this: "I" create an object (and set it's reference
to 1). I give this object to the CM (IB_CM_LISTEN(obj)). The CM wants to do a
call back in the future, so he increases the reference count to 2. Now I forget
about the object and release my reference (back to 1). The CM receives a request
and wants to call my call back. He does this without increasing the reference. I
use the object during the callback. If I want to keep it I increase the
reference count. Now let's say that after 50 callbacks he has some error. He
calls the error callback and releases his reference count since he doesn't want
to use the object any more. The reference went to 0 and the object is being
destroyed (release understands that the reference has reached 0 and call the
destroy automatically). 

This seems error prone to me.  If you no longer want an object and decrement its
reference count, you could very well destroy the associated context.  Getting a
callback after this is likely to crash.  This model seems to increase the
complexity for a ULP.  How can a ULP unload?  How can it signal the CM that it
will no longer be around to receive a callback?  An app that allocates an object
can't simply forget about it.  Using this method, the creator of the object will
never know if a callback will occur for some past created object, so can never
cleanup anything associated with the object.

- Sean

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