Re: replacing the default CA exception handler

[Marty Kraimer <mrk@aps.anl.gov>]

Jeff Hill wrote:

> Perhaps I should just have a call in the CA client library -
> ca_disable_exeception_aborts() - so that the default exception
> handler can be used.
> 

I vote for this.

> Changing topics:
> Persons developing CA client applications have asked for the
> capability to replace the function that gets called when CA prints
> a diagnostic message so messages don't go to stderr and they go to
> some log file instead. This capability was provided in
> the form of ca_replace_printf_handler().
> 
> Perhaps Marty will get the same request with
> errlogPrintf() when it is used more often in standalone applications.
> If this functionality is added then I can base the client lib on
> errlogPrintf() while remaining backwards compatible with
> ca_replace_printf_handler()? If so I could eliminate some
> redundant code and reduce interdependency between the
> client and server libraries.


This sound like a good idea BUT.

errlogPrintf is actually a family of routines and currently have completely
different implementation of the host and of the ioc.

On the host it would be possibly to just provide a call

errlogReplaceVprintf(...)

This would work fine. BUT is this really needed. Maybe the answer is yes.

On the ioc an errlog call transfers a message to another task. This other task
already supports errlogAddListener. If no listeners are attached nothing is
displayed. Base currently base supplies iocLogClient which calls
errlogAddListener. iocLogClient passes the messages to a logServer. Other code
can also call errlogAddListener. For example CDEV provides code that calls
errlogAddListener and passes the messages to the CDEV error log server. errlog
on the iocs also provides a shell callable switch that decides if messages
should also be displayed via printf. Thus for the ioc version of errlog I
maintain that no additional flexability is required.

Marty Kraimer