Re: "mode" and varios processes sharing the same queue for writting

[Eric Wong <normalperson@yhbt.net>]

Iñaki Baz Castillo <ibc@aliax.net> wrote:
> Hi, I'll have an external process (running as root) which creates a posix_mq 
> queue just for read-only. As it runs as root I can set a longer "maxmsg" 
> value.
> 
> Then I've other processes (Unicor workers) running as non privileged users and 
> must write in that queue.
> 
> So in the external process I do:
> 
>   File.umask(0000)
>   MQ = POSIX_MQ.new "/mq", IO::RDONLY | IO::CREAT, 00002
> 
> "mode" = 00002 which means "others have write permission" (in combination with 
> the modified umask, of course, if not it doesn't work).
> 
> Is it the correct approach?
> 
> 
> And the other question: Being posix_mq process/thread safe, does it mean that 
> I could open the queue writter in the master process so it could be safely 
> shared by all the workers? or shall I open the queue writter for each worker?

Hi Iñaki,

I'm glad you were able to answer your own questions while I was away.
Yes the mode argument is handled exactly like how the open(2) syscall
works (and File.open(), too).

> PS: Thanks a lot for this project, it's exactly what I needed (much better 
> than using DRb o UNIXsockets) :)

No problem, I'm glad this POSIX feature is getting more exposure :)

> PPS: Is there any other cool project you are involved in? :)

"cool" is up for the users to decide :)  I strongly prefer people
evaluate/use projects without taking the reputation (good or bad)
of the author(s) into account.

Of course I'll announce any worthwhile Ruby projects I release on
ruby-talk/RAA and use language/community-specific mailing lists
and/or Freshmeat.

-- 
Eric Wong