* [9fans] A question about timeout
@ 2009-07-14 14:21 Adriano Verardo
2009-07-14 14:47 ` cinap_lenrek
0 siblings, 1 reply; 4+ messages in thread
From: Adriano Verardo @ 2009-07-14 14:21 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
I'm porting some Unix applications which implement a timeout on
read/write/accept/... calls using select().
In previous versions I did the same by signals but with problems
due to the behaviour of the interrupted system call.
Select() is also used to choose among channels waiting for I/O.
How can I implement channel selection and secure timeouts
without using APE ?
Re-write some pieces is not a problem, I prefer a "pure" 8c implementation.
adriano
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [9fans] A question about timeout
2009-07-14 14:21 [9fans] A question about timeout Adriano Verardo
@ 2009-07-14 14:47 ` cinap_lenrek
2009-07-14 17:41 ` Adriano Verardo
0 siblings, 1 reply; 4+ messages in thread
From: cinap_lenrek @ 2009-07-14 14:47 UTC (permalink / raw)
To: 9fans
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to interrupt on i/o operations you send a note to the process.
for ioproc(2), here is iointerrupt() that does that. for timeouts here is
a alarm() function (see sleep(2)) that will fire a note on you when the alarm expires.
notes should also work for rendezvous()/alt(), but a better way is to include
a timeout/cancel channel in your alt() operation. as a example see
/sys/src/cmd/rio/time.c. here we have a central timer process
that does a sleep and sends a message to channels associated
with timers when they expire.
--
cinap
[-- Attachment #2: Type: message/rfc822, Size: 2747 bytes --]
From: Adriano Verardo <a.verardo@tecmav.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: [9fans] A question about timeout
Date: Tue, 14 Jul 2009 16:21:08 +0200
Message-ID: <4A5C9454.9080801@tecmav.com>
I'm porting some Unix applications which implement a timeout on
read/write/accept/... calls using select().
In previous versions I did the same by signals but with problems
due to the behaviour of the interrupted system call.
Select() is also used to choose among channels waiting for I/O.
How can I implement channel selection and secure timeouts
without using APE ?
Re-write some pieces is not a problem, I prefer a "pure" 8c implementation.
adriano
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [9fans] A question about timeout
2009-07-14 14:47 ` cinap_lenrek
@ 2009-07-14 17:41 ` Adriano Verardo
2009-07-14 19:01 ` cinap_lenrek
0 siblings, 1 reply; 4+ messages in thread
From: Adriano Verardo @ 2009-07-14 17:41 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
cinap_lenrek@gmx.de wrote:
> to interrupt on i/o operations you send a note to the process.
> for ioproc(2), here is iointerrupt() that does that. for timeouts here is
> a alarm() function (see sleep(2)) that will fire a note on you when the alarm expires.
> notes should also work for rendezvous()/alt(), but a better way is to include
> a timeout/cancel channel in your alt() operation. as a example see
> /sys/src/cmd/rio/time.c. here we have a central timer process
> that does a sleep and sends a message to channels associated
> with timers when they expire.
>
> --
> cinap
Thank you very much.
Where can I find the explanation of the interrupted system calls behaviour ?
In Unix I sometimes found quite difficult to deal with them.
What about Plan9 ?
adriano
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [9fans] A question about timeout
2009-07-14 17:41 ` Adriano Verardo
@ 2009-07-14 19:01 ` cinap_lenrek
0 siblings, 0 replies; 4+ messages in thread
From: cinap_lenrek @ 2009-07-14 19:01 UTC (permalink / raw)
To: 9fans
[-- Attachment #1: Type: text/plain, Size: 269 bytes --]
its best to look at the manpage for the function to check
what happens in the case of interruption. but they usualy
just return -1 and set errstr will contain the string
"interrupted". plan9 does no syscall restarting.
read notify(2) and thread(2).
--
cinap
[-- Attachment #2: Type: message/rfc822, Size: 3176 bytes --]
From: Adriano Verardo <a.verardo@tecmav.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] A question about timeout
Date: Tue, 14 Jul 2009 19:41:27 +0200
Message-ID: <4A5CC347.7080806@tecmav.com>
cinap_lenrek@gmx.de wrote:
> to interrupt on i/o operations you send a note to the process.
> for ioproc(2), here is iointerrupt() that does that. for timeouts here is
> a alarm() function (see sleep(2)) that will fire a note on you when the alarm expires.
> notes should also work for rendezvous()/alt(), but a better way is to include
> a timeout/cancel channel in your alt() operation. as a example see
> /sys/src/cmd/rio/time.c. here we have a central timer process
> that does a sleep and sends a message to channels associated
> with timers when they expire.
>
> --
> cinap
Thank you very much.
Where can I find the explanation of the interrupted system calls behaviour ?
In Unix I sometimes found quite difficult to deal with them.
What about Plan9 ?
adriano
^ permalink raw reply [flat|nested] 4+ messages in thread
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2009-07-14 14:21 [9fans] A question about timeout Adriano Verardo
2009-07-14 14:47 ` cinap_lenrek
2009-07-14 17:41 ` Adriano Verardo
2009-07-14 19:01 ` cinap_lenrek
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