Re: TIP #233: Virtualization of Tcl's Sense of Time

From: Andreas Kupries (akupries_at_shaw.ca)
Date: 12/10/04 

{Path: bluepeak.shaw.ca!not-for-mail
Date: Fri, 10 Dec 2004 01:05:29 GMT

"KRF" <kfitch@notes.westinghouse.com> writes:

> Will the implementation handle "negative time steps"?

> In other words, if the supplied procedure returns a time which is
> earlier than the previous time it returned, what will happen with
> all the timer based stuff (e.g. pending after commands)?

Kevin Kenny talked about that in a post to tcl-core, I believe. It was
in the context of the OS clock going backwards, but the principle is
the same, as these hooks allow us to supply our own 'OS clock' to Tcl.

IIRC the trigger times for pending after commands are stored as
absolute values, i.e. the absolute time to trigger at. And the core
will wait until the OS supplies it with that time, or one later than
it, before it triggers the after.

So if the clock runs backward the time until the after triggers is
extended. 

-- 
So long,
	Andreas Kupries <akupries@shaw.ca>
			<http://www.purl.org/NET/akupries/>
	Developer @	<http://www.activestate.com/>
-------------------------------------------------------------------------------
}

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