Re: [Lcd4linux-devel] How to do an asynchronous plugin

[Michael R. <re...@eu...>]

Hi Javi,

> First I want to do is to turn them to run asynchronous, but I really
> have no idea about how to do it.
Async would be great. In fact, it's necessary here...

> If I do a fork inside the pluging...
YOu don't use fork() directly, but some helper functions provided by
thread.[ch] Here you'll find functions to pass values between the
processes, too.

> how can I do to read from de parent process values that are written
> by the child process, but without waiting for the child to end? Is
> there a way to child writes a value ("global variable"?) and the
 > parent  reads it's from a "shared memory"?

you have to create a mutex for every value you want to pass,
mutex_lock() it before reading and writing, and mutex_unlock() it
afterwards.

The value itself must be a shared memory segment created with shm_create()

The child process itself is created with thread_create().

Take a look at plugin_exec.c, it uses exactly this technique.

If you have any questions, feel free to ask.


bye, Michael

-- 
Michael Reinelt                                   Tel: +43 676 3079941
Geisslergasse 4                                   Fax: +43 316  692343
A-8045 Graz, Austria                          e-mail: re...@eu...