Trigger should know what regions of data are safe

[JelleAalbers]

Readers insert data asynchronously into the database, so at a given time the most recent data in the database is incomplete -- not all digitizers have contributed to it. The trigger queries data until a fixed time (one minute) away from the last pulse for this reason.

Such a fixed margin is not robust. If the database is too slow, or a pulse is accidentally inserted into the far future (some issues we had in the past), the trigger still queries a region of data it shouldn't, and the result is stretches of time where not all digitizers contribute.

Dan already implemented a 'status' database collection where the digitizers keep track of which collections are safe to read. There's also at least a start of code in the trigger to use this. When there is time, we should test if this works well and switch to it.