Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 16 Feb 2009 10:37:13 -0600

Hi Ben,

On Monday 16 February 2009 05:07:12 Benjamin Franksen wrote:
>
> it seems that CA output links do not work at all during PINI processing if
> the target record is on the same IOC.

> I think this is a bug, as I could not find any note on this behaviour in
> the Developer's Guide.

Please consider the task of bringing up an IOC, i.e. what iocInit does.  Here 
are some lines from iocInit, in order of execution:

    initialProcess();

    /* Start CA server threads */
    rsrv_init();
...
   /* Enable scan tasks and some driver support functions.  */
    scanRun();
    dbCaRun();
...
    rsrv_run();

The CA server has not even been initialized when the initialProcess() (i.e. 
PINI processing) takes place, and the dbCa link task which manages CA links 
is not running at that point either.  PINI has to happen before we release 
the scan threads or allow CA links to connect because they can initiate 
record processing.

We can't allow external CA clients to connect before the PINI processing is 
done because they might interfere with that initialization, and I suspect it 
would be hard to add a separate path to the server to allow internal CA 
clients to connect in advance of the external ones.

I agree that the documentation does not discuss PINI much, but [despite being 
slightly out-dated by R3.14.10] section 7.4 of the AppDevGuide does make 
clear that initialProcess() happens before rsrv_init().

- 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