cet-is » art

We had a configuration like this:

path1: [ filt, prod1, prod2 ]
path2: [ prod3 ]

Where the producer modules prod2 and prod3 depend on the output of prod1.

When filt rejects an event, prod1 and prod2 don't run, but prod3 still does, and then fails with a ProductNotFound exception because prod1 didn't produce its product.

I guess this file can't be a configuration error, because it's possible prod3 doesn't use prod1's output, but it could be detected at runtime with a message like:

"prod3 called getByLabel() for 'prod1', but 'prod1' is after filter 'filt'. Call may fail when 'filt' rejects an event".

Perhaps there are situations where prod3 can be relied upon to do effectively the same filtering internally, in which case the error when the ProductNotFound exception is thrown could still be improved:

"ProductNotFound: 'prod1' did not run in this Event because 'filt' rejected it".

It otherwise isn't immediately apparent what the problem is, especially when filt rarely rejects events.