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pipes - reading buffer less than PIPE_BUF is atomic operation?

Hi !

I read that writing to pipe buffer less that PIPE_BUFF made in atomic opreation. Does the same apply to reading from pipe ?

I want to use pipe with one writer and multiple reader and want to make sure that pipes does the work without that i need to use semaphore betweent the readers.

Thanks !
Gal.

Quote:

Originally Posted by gal_netanel (Post 2986879)

I read that writing to pipe buffer less that PIPE_BUFF made in atomic opreation. Does the same apply to reading from pipe ?

Yes. Though I am not 100% sure, but it would amaze me if reading from a pipe (less than PIP_BUFF) is not atomical.

Quote:

Originally Posted by gal_netanel (Post 2986879)

I want to use pipe with one writer and multiple reader and want to make sure that pipes does the work without that i need to use semaphore betweent the readers.

Pipes are one-way and one-to-one only. So to have one writer and multiple readers you would have to create (and write to) as much pipes as there are reader-processes.

I'd recommend using a UNIX-domain socket (also called "filesystem socket" or "local socket") instead.

You can read about pipes and UNIX-domain socket in this PDF.

Quote:

Originally Posted by Hko (Post 2988084)

Yes. Though I am not 100% sure, but it would amaze me if reading from a pipe (less than PIP_BUFF) is not atomical.

Pipes are one-way and one-to-one only. So to have one writer and multiple readers you would have to create (and write to) as much pipes as there are reader-processes.

I'd recommend using a UNIX-domain socket (also called "filesystem socket" or "local socket") instead.

You can read about pipes and UNIX-domain socket in this PDF.

Thank you very much Hko.
I found the pdf file very interesting.
Regards, Gal.