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archiver-appliance / epicsarchiverap

This is an implementation of an archiver for EPICS control systems that aims to archive millions of PVs.
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Retaining event field information when Optimized and OptimizedWithLastSample post-processors return non-binned events #122

Closed rjwills28 closed 1 year ago

rjwills28 commented 3 years ago

We wanted to be able to detect when a PV had become disconnected so that we could show it in the CS-Studio data browser. We followed the advice discussed in the issue https://github.com/slacmshankar/epicsarchiverap/issues/96 to get the fields 'cnxlostepsecs' from the extra fields in the RAW response or if using the Optimized or OptimizedWithLastSample postprocessors the 'connectionChange' field added by the AA.

However we found a special case where the information on a disconnect is completely lost. If the user requests Optimized or OptimizedWithLastSample data but the number of bins is larger than the number of events in a time period, then the raw events get transformed into a POJOEvent and returned. This type of event has no capacity to hold the extra fields information and so loses any information on the disconnect.

This PR contains a fix for this by retaining the original event fields instead of creating a new POJOEvent.

The PR also contains a minor bug fix in the OptimizedWithLastSample.java code to check 2 objects are not null before using them (bug found will testing the above).

aawdls commented 2 years ago

Hi @slacmshankar - please can we request a review on this when you have the chance. Thanks!