* [9fans] Does 9P provide multicast for files?
@ 2011-03-23 20:23 Robin Bate Boerop
2011-03-23 20:38 ` Gorka Guardiola
0 siblings, 1 reply; 4+ messages in thread
From: Robin Bate Boerop @ 2011-03-23 20:23 UTC (permalink / raw)
9fans,
I am new to Plan9 and 9P, and have not found the answer to my question
in documentation:
With 9P, what happens when 2 readers have the same file open, both are
blocked on a read() call, and then a writer writes to the file; which
of the readers sees the data? Both?
^ permalink raw reply [flat|nested] 4+ messages in thread
* [9fans] Does 9P provide multicast for files?
2011-03-23 20:23 [9fans] Does 9P provide multicast for files? Robin Bate Boerop
@ 2011-03-23 20:38 ` Gorka Guardiola
2011-03-23 20:55 ` erik quanstrom
0 siblings, 1 reply; 4+ messages in thread
From: Gorka Guardiola @ 2011-03-23 20:38 UTC (permalink / raw)
> With 9P, what happens when 2 readers have the same file open, both are
> blocked on a read() call, and then a writer writes to the file; which
> of the readers sees the data? Both?
Both readers and writers are clients of a 9p file server. It decides who to answer. It is not specified by the protocol.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [9fans] Does 9P provide multicast for files?
2011-03-23 20:38 ` Gorka Guardiola
@ 2011-03-23 20:55 ` erik quanstrom
2011-03-23 21:41 ` Robin Bate Boerop
0 siblings, 1 reply; 4+ messages in thread
From: erik quanstrom @ 2011-03-23 20:55 UTC (permalink / raw)
On Wed Mar 23 16:43:55 EDT 2011, paurea at gmail.com wrote:
>
> > With 9P, what happens when 2 readers have the same file open, both
> are > blocked on a read() call, and then a writer writes to the file;
> which > of the readers sees the data? Both?
>
> Both readers and writers are clients of a 9p file server. It decides
> who to answer. It is not specified by the protocol.
excellent answer.
i'd like to add, though, since tags are chosen by the client,
the 9p messages can't be multicast at the transport or
network layer.
so if data becomes available that could unblock both readers
the file server may pick one, neither, or send the same data
(with different tags, etc) to both.
- erik
^ permalink raw reply [flat|nested] 4+ messages in thread
* [9fans] Does 9P provide multicast for files?
2011-03-23 20:55 ` erik quanstrom
@ 2011-03-23 21:41 ` Robin Bate Boerop
0 siblings, 0 replies; 4+ messages in thread
From: Robin Bate Boerop @ 2011-03-23 21:41 UTC (permalink / raw)
On 23 March 2011 17:55, erik quanstrom <quanstro at quanstro.net> wrote:
> On Wed Mar 23 16:43:55 EDT 2011, paurea at gmail.com wrote:
>> Both readers and writers are clients of a 9p file server. ?It decides
>> who to answer. ?It is not specified by the protocol.
>
> excellent answer.
>
> i'd like to add, though, since tags are chosen by the client,
> the 9p messages can't be multicast at the transport or
> network layer.
>
> so if data becomes available that could unblock both readers
> the file server may pick one, neither, or send the same data
> (with different tags, etc) to both.
Erik and Gorka, thank you for the prompt and clear answers.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2011-03-23 20:23 [9fans] Does 9P provide multicast for files? Robin Bate Boerop
2011-03-23 20:38 ` Gorka Guardiola
2011-03-23 20:55 ` erik quanstrom
2011-03-23 21:41 ` Robin Bate Boerop
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