RE: Children of dead processes

John,

Philip raises excellent questions, and I'm very much in favor of mandating that parent process objects with live children should not be deleted. It provides a nice, clean, intuitive semantics with no "surprises" for the user.

Thanks,
-Bishnupriya

From: john.aynsley@doulos.com [mailto:john.aynsley@doulos.com]
Sent: Tuesday, January 11, 2011 6:04 PM
To: Bishnupriya Bhattacharya; philipp.hartmann@offis.de; systemc-p1666-technical@eda.org
Subject: Children of dead processes

All,

Philipp has raised the following issues:

6.6.5 sc_process_handle::get_parent_object
6.16.7 sc_object::get_parent_object

  "If the parent object is a process instance and that process has terminated, get_parent_object shall return either a pointer to the surviving process instance or a null pointer if it has been deleted."

 What happens to the object's position itself, when the parent object is NULL?

   - It can still be found via sc_find_object( obj.name() )?

   - Is it moved to the top-level, i.e. can it be found via sc_get_top_level_objects()?

   - But then basename() != name(), but (since no parent)
     get_parent_object()->name() '.' basename() != name()
     (The name can't be changed, since it is meant to stay valid until the object is deleted?)

 This may affect sc_event naming as well.

6.16.1 sc_object Description (see get_parent_object above)

  "... objects of a class derived from sc_object may be deleted at any time. When such an sc_object is deleted, it ceases to be a child."

  If it has child objects itself (in case of a process), what happens to their position in the hierarchy? And their names?

  I would even prefer to have a restriction that in case, the "parent" object shall not be deleted/invalidated until all children have been deleted. But this might break "early invalidating" implementations.

[JA] We have already agreed that dynamic processes may be terminated while they still have children, in which case a call to get_parent_object() for any orphaned objects returns a null pointer. On the other hand, insisting that parent process objects cannot be deleted while they have surviving children would be a clean solution.

Opinions?

John A

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