* [9fans] Bread + note -> loss
@ 2014-05-12 15:10 erik quanstrom
2014-05-12 16:18 ` cinap_lenrek
0 siblings, 1 reply; 8+ messages in thread
From: erik quanstrom @ 2014-05-12 15:10 UTC (permalink / raw)
To: 9fans
in looking at a particular situation with Bread, i noticed that it
Bgetc, and Bgetrune differ from Brdstr in what it does with read
returns a count <= 0. Brdstr just returns nil. Bread sets Binactive.
this wouldn't matter if there were not two fundamentally different
types of notes: alarms and everything else. (from this perspective
it seems a shame that plan 9 doesn't allow syscalls to be restarted.)
for the interrupted case, this Bread with a different, undocumented,
(and bizarre) recovery strategy. a Bseek(b, 0, 1) will rejuvinate the
Biobuf for Bread, but one must carefully paste the interrupted slop
together with a second response if one wishes to recover from an
interrupted read.
so, boo. this seems like a real painful corner case. and i don't see
any easy way out, unless bio were modified to allow read and write
to be replaced with indirect function calls. this might be very interesting
for threaded applications.
crazy?
- erik
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] Bread + note -> loss
2014-05-12 15:10 [9fans] Bread + note -> loss erik quanstrom
@ 2014-05-12 16:18 ` cinap_lenrek
2014-05-12 16:21 ` erik quanstrom
2014-05-12 16:31 ` erik quanstrom
0 siblings, 2 replies; 8+ messages in thread
From: cinap_lenrek @ 2014-05-12 16:18 UTC (permalink / raw)
To: 9fans
why not check the error string in Bread() and see if its "interrupted"
and in that case, dont inactivate the stream? or are i'm missing
something?
--
cinap
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] Bread + note -> loss
2014-05-12 16:18 ` cinap_lenrek
@ 2014-05-12 16:21 ` erik quanstrom
2014-05-12 16:31 ` erik quanstrom
1 sibling, 0 replies; 8+ messages in thread
From: erik quanstrom @ 2014-05-12 16:21 UTC (permalink / raw)
To: 9fans
On Mon May 12 12:19:47 EDT 2014, cinap_lenrek@felloff.net wrote:
> why not check the error string in Bread() and see if its "interrupted"
> and in that case, dont inactivate the stream? or are i'm missing
> something?
that's an excellent suggestion. i thought about it before posting, but
sort of discarded that line of thinking. i think the difficulty might
be in disturbing programs that depend on this behavior.
- erik
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] Bread + note -> loss
2014-05-12 16:18 ` cinap_lenrek
2014-05-12 16:21 ` erik quanstrom
@ 2014-05-12 16:31 ` erik quanstrom
2014-05-12 16:41 ` cinap_lenrek
1 sibling, 1 reply; 8+ messages in thread
From: erik quanstrom @ 2014-05-12 16:31 UTC (permalink / raw)
To: 9fans
i should elaborate. the case were any error or interrupt looks like Beof
seems like the right thing for any program that looks like a filter. this
is the majority of programs. and this is the current behavior. i wouldn't
want to make the simple case tricky. but the hard case should also not
be impossible or impossibly tricky, either.
the suggestion of having Biobuf.^(read|write) skirts this issue buy allowing
a sophisticated program to interrupt itself and recover gracefully, without
letting Bio in on the joke.
- erik
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] Bread + note -> loss
2014-05-12 16:31 ` erik quanstrom
@ 2014-05-12 16:41 ` cinap_lenrek
2014-05-14 16:59 ` erik quanstrom
0 siblings, 1 reply; 8+ messages in thread
From: cinap_lenrek @ 2014-05-12 16:41 UTC (permalink / raw)
To: 9fans
why? if the program doesnt handle the note, then it shouldnt matter if it
clunks the biobuf or not as it will be exited by the default handler.
--
cinap
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] Bread + note -> loss
2014-05-12 16:41 ` cinap_lenrek
@ 2014-05-14 16:59 ` erik quanstrom
2014-05-16 19:24 ` cinap_lenrek
0 siblings, 1 reply; 8+ messages in thread
From: erik quanstrom @ 2014-05-14 16:59 UTC (permalink / raw)
To: 9fans
On Mon May 12 12:42:21 EDT 2014, cinap_lenrek@felloff.net wrote:
> why? if the program doesnt handle the note, then it shouldnt matter if it
> clunks the biobuf or not as it will be exited by the default handler.
you're right.
- erik
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] Bread + note -> loss
2014-05-14 16:59 ` erik quanstrom
@ 2014-05-16 19:24 ` cinap_lenrek
2014-05-16 19:29 ` erik quanstrom
0 siblings, 1 reply; 8+ messages in thread
From: cinap_lenrek @ 2014-05-16 19:24 UTC (permalink / raw)
To: 9fans
btw, whats the program that gets hit by alarm notes but wants to
continue with Bread()?
--
cinap
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] Bread + note -> loss
2014-05-16 19:24 ` cinap_lenrek
@ 2014-05-16 19:29 ` erik quanstrom
0 siblings, 0 replies; 8+ messages in thread
From: erik quanstrom @ 2014-05-16 19:29 UTC (permalink / raw)
To: 9fans
On Fri May 16 15:26:28 EDT 2014, cinap_lenrek@felloff.net wrote:
> btw, whats the program that gets hit by alarm notes but wants to
> continue with Bread()?
there's one you wrote, but more on that offline.
- erik
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2014-05-16 19:29 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2014-05-12 15:10 [9fans] Bread + note -> loss erik quanstrom
2014-05-12 16:18 ` cinap_lenrek
2014-05-12 16:21 ` erik quanstrom
2014-05-12 16:31 ` erik quanstrom
2014-05-12 16:41 ` cinap_lenrek
2014-05-14 16:59 ` erik quanstrom
2014-05-16 19:24 ` cinap_lenrek
2014-05-16 19:29 ` erik quanstrom
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