Experimental Physics and Industrial Control System
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On Thu, 27 Aug 2020 at 18:19, Johnson, Andrew N. < anj at anl.gov> wrote:
On Aug 27, 2020, at 9:45 AM, Ralph Lange via Tech-talk < tech-talk at aps.anl.gov> wrote:
Now, in that -no_cache mode, when a monitor connection to the PV exists and an additional external client connects - what should the Gateway do?
It doesn't have the cached value, so it must do another get() on the inside to the IOC. When the answer to that get() arrives, it can't be distinguished from a monitor update. So with a list of clients for that PV, which ones should get the update,
which shouldn’t?
Why can’t that ca_get_callback() be distinguished, couldn’t it use a different pFunc and/or pArg than the monitors use? That would allow the gets to trigger different behavior (i.e. not update the cached value or forward this event to the monitoring clients).
Why, oh why? As I said: The code can certainly be improved. Express yourself. And remember to keep it simple.
Sorry for this answer of limited constructiveness - maybe tomorrow. ~Ralph
- References:
- Receiving duplicate monitor values using CA PV Gateway Juan F. Esteban Müller via Tech-talk
- Re: Receiving duplicate monitor values using CA PV Gateway Ralph Lange via Tech-talk
- Re: Receiving duplicate monitor values using CA PV Gateway Johnson, Andrew N. via Tech-talk
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ANJ, 27 Aug 2020 |
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