put callback queuing

[Daron Chabot <daron.chabot@gmail.com>]

Hi,

Recently at BNL, we've been investigating a report of unexpected
behavior found when using put-callbacks to a Motor Record (verified
using a simulated motor). After initiating a long-running motion with

caput -c -w 100 test:motor1 <some large value>

trying to stop the motor in the following way fails:

caput -c -w 100 test:motor1.STOP 1

After observing that the 2nd put-with-callback to stop the motion is
not seen by the Motor Record, a look through
$EPICS_BASE/src/rsrv/camessage.c reveals that concurrent put notifies
are queued in the IOC server:

/******************************/
if ( pciu->pPutNotify ) {

        /*
         * serialize concurrent put notifies
         */
/******************************/

I can understand serializing put-callbacks on a per-channel basis, but
the implementation appears to serialize _per-record_.

What am I missing? A little help please...


-- dc