Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Wed, 21 Jan 2009 12:06:55 -0600

Hi Doug,

On Tuesday 20 January 2009 20:01:48 Douglas Morrison wrote:
>
> Using this setup I successfully get callback events. Did I misunderstand
> the documentation when it said the CA Library would create its own event
> processing threads, and that the second method I employ is actually the
> correct method?

If you're enabling preemtive callbacks you do not need your own dispatcher 
thread, CA will run your callbacks from its internal threads.  You don't 
actually need to call ca_pend_event() at all, just remember to ca_flush() as 
Jeff suggested when you've done all your setup.

> Final question: When using preemptive callbacks, performing a select on
> the file descriptors created by channel connections no longer see any
> change on the sockets. Why is this (what is the motivation)?

I'm not sure I completely understand the question; we don't use select() any 
more in the R3.14.x CA library, all I/O is performed using background threads 
(two per server).

- Andrew
-- 
The best FOSS code is written to be read by other humans -- Harold Welte

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System