RE: reset method

Bishnupriya,

I would prefer to rename sc_kill_exception to sc_unwind_exception to make
the name neutral with respect to kill() and reset(), throw the same
exception for both, and add a method bool is_reset() that could be tested
in a catch block (under exceptional circumstances ;-)

John A

From:
Bishnupriya Bhattacharya <bpriya@cadence.com>
To:
"john.aynsley@doulos.com" <john.aynsley@doulos.com>
Cc:
David C Black <dcblack@xtreme-eda.com>, "systemc-p1666-technical@eda.org"
<systemc-p1666-technical@eda.org>
Date:
22/07/2010 20:16
Subject:
RE: reset method

John,
 
I think you have a valid use case in mind, and the standard will indeed be
cleaner with a way to distinguish between the two.
 
How best to go about it?
 
Since the exception is really for stack unwinding, should we have an
abstract base class sc_unwind_stack_exception with pure virtual member
is_reset(), and have sc_reset_exeception and sc_kill_exception both derive
from this base class? Typically, user code won't need to distinguish
between kill and reset, and can only catch sc_unwind_stack_exception. Code
that wants to distinguish (likely the kernel) can catch the more derived
classes.
 
The alternative of having reset_exception derive from kill_exception or
vice versa might be a little confusing/misleading, as neither
functionality is a strict subset or superset of the other.
 
If we wanted to really keep it simple, and not deviate much from the
current spec, I think the purpose is also served (perhaps not so
elegenatly) by only having the sc_kill_exception class, and giving it a
member method "bool is_reset()" that returns false for kill and true for
reset.
 
Thoughts? Is a separate sc_unwind_stack_exception class an overkill? Or an
overreset :-)
 
Thanks,
-Bishnupriya
 

From: john.aynsley@doulos.com [mailto:john.aynsley@doulos.com]
Sent: Thursday, July 22, 2010 10:56 PM
To: Bishnupriya Bhattacharya
Cc: David C Black; systemc-p1666-technical@eda.org
Subject: RE: reset method

Bishnupriya,

Yes, but I don't have any specific agenda here other than creating a clean
standard. I have not got any burning issues in mind. I guess that most of
the time there would be no reason to distinguish between the two kinds of
cleaning up, but I can imagine that a process that was collecting
diagnostic information might want to handle it differently for a reset
versus a kill, e.g. perhaps retain some diagnostic state information
across the reset.

John A

From:
Bishnupriya Bhattacharya <bpriya@cadence.com>
To:
"john.aynsley@doulos.com" <john.aynsley@doulos.com>, David C Black
<dcblack@xtreme-eda.com>, "systemc-p1666-technical@eda.org"
<systemc-p1666-technical@eda.org>
Date:
22/07/2010 18:05
Subject:
RE: reset method

John,
  
Let me understand your objective better. You want that while a process is
being killed/reset, there be some way of telling which is happening? For
example, if the process itself catches sc_kill_exception, and wants to do
one kind of cleanup or another based on whether it is getting killed or
reset. Is that the objective?
  
Thanks,
-Bishnupriya

From: john.aynsley@doulos.com [mailto:john.aynsley@doulos.com]
Sent: Thursday, July 22, 2010 9:14 PM
To: David C Black; Bishnupriya Bhattacharya;
systemc-p1666-technical@eda.org
Subject: Re: reset method

Bishnupriya,

It's nice to be able to catch and handle kills and resets, but I don't
think it's important enough to justify anything but the simplest
mechanism. I would have thought that most of the time kills and resets
could be handled in the same way.

I was musing on some other way of telling whether the process had been
killed or reset, and method terminated() came to mind, but presumably a
killed process would not get terminated until the exception was caught by
the kernel, so that's no good.

I am arguing semantics here, but if we have a common exception, that
exception does not necessarily terminate the process, because it is being
used for both reset() and kill(): reset() does not leave the process
terminated. So having class sc_kill_exception: public sc_reset_exception
makes more sense to me, with the sc_reset_exception actually doing the
work of unwinding the stack. Does that work?

John A

From:
David C Black <dcblack@xtreme-eda.com>
To:
systemc-p1666-technical@eda.org
Date:
21/07/2010 21:16
Subject:
Re: reset method
Sent by:
owner-systemc-p1666-technical@eda.org

If you're going to throw an exception anyhow, then I would prefer the
sc_reset_exception solution over adding another member method.

------------------------------------------------------
David C Black, XtremeEDA ESL Practice Leader
http://www.Xtreme-EDA.com
(Consulting, Services & Training for all your ESL, verification and DFT
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On Jul 21, 2010, at 2:49 PM, Bishnupriya Bhattacharya wrote:

John,
 
Yes reset() throws an sc_kill_exception.
 
It is a good idea to distinguish reset from kill by using the exception. I
suggest a member method in the sc_kill_exception class - "bool reset()" -
or perhaps have sc_reet_exception that derives from sc_kill_exception?
 
WDYT?
 
Thanks,
-Bishnupriya

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