RE: Children of dead processes

That's right.

-Bishnupriya
From: john.aynsley@doulos.com [mailto:john.aynsley@doulos.com]
Sent: Wednesday, January 12, 2011 6:20 PM
To: Bishnupriya Bhattacharya
Cc: philipp.hartmann@offis.de; systemc-p1666-technical@eda.org
Subject: RE: Children of dead processes

Bishnupriya, Philipp,

Agreed. So as I understand it, we are proposing that for every occurrence of get_parent_object() in the LRM, we change the description to say that the following:

If the parent object is a process instance and that process has terminated, get_parent_object shall return a pointer to the process instance. The parent process instance shall not be deleted while the process instance has child objects, but may be deleted once all its child objects have been deleted

Right?

John A

From:

Bishnupriya Bhattacharya <bpriya@cadence.com>

To:

"john.aynsley@doulos.com" <john.aynsley@doulos.com>, "philipp.hartmann@offis.de" <philipp.hartmann@offis.de>, "systemc-p1666-technical@eda.org" <systemc-p1666-technical@eda.org>

Date:

11/01/2011 18:14

Subject:

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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