Experimental Physics and
Industrial Control System

Records in different lock sets can interleave their processing as
task priorities and required resources permit.  You have to assume
records not in your lock set and not otherwise constrained by
mutexes, etc. will process in parallel with you, and that they will
try to find a way to interfere with you.

I don't know enough about StreamDevice's locking to put limits on
what it can accomplish without help from device-level code.

Asyn has support for arranging exclusive access, to a device or port,
that persists until it's rescinded.  See 'blockProcessCallback' in
asynDriver.html.  (I don't know what existing asyn support uses this,
and I haven't written any code that does.)

Can someone please explain a few more details about epics processing sequences of FLNK-ed records. Once an flnk-ed sequence begins, can/will another different flnked sequence begin?
Do I have to assume that unrelated (no shared PVs) flnk-ed series can/will run in parallel?
In our case, I have a series of records that implements several reads of a slow serial stream device, and associated other processing. I would like to protect against a user setting a PV that will cause a write to that same device before my series of reads is finished. Do I need to implement some protection? I do know about the statement in the StreadDevice manual that says, "The first out command in the protocol locks the device for exclusive access. That means that no other record can communicate with that device." But I think I'm looking for a different locking across a sequence of records.

Thanks!
Dennis

--
Tim Mooney ([email protected]) (630)252-5417
Beamline Controls & Data Acquisition Group
Advanced Photon Source, Argonne National Lab.

References:

do flnk-ed sequences of records get interrupted? Dennis Nicklaus

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