The purpose of environment store (EnvStore) is to keep records of all transitions so that they can be retrieved later using the timestamp of an event. There are three types of EnvStore:
- epics
- scans
- step
Envstore epics and scans are created when "epics" or "scan" keyword is found in the configs. The variables and values are stored as a dictionary in this format:
{alg: {segment_id: {var_name: var_type, }, }, }
To retrieve a value,
edet = run.Detector('epix_variable_name')
val = edet(evt)
This is done by first locating alg and segment_id that store this variable then matching dgram(s) in the EnvStore is retrieved by searching with timestamp. We then get the value from dgram.epics.alg[segment_id].var_name.
EnvStore step is created by default and has detector names with 'config' attribute stored in cfgscan_detnames property (e.g. configs[0].tmoopal[0].config.user.black_level → 'tmoopal' is stored cfgscan_detnames).
sdet = run.Detector('tmoopal')
step_value = sdet.step.step_value(evt) # this will fail if this detector doesn't have "config" as its attribute in configs – see above
step_docstring = sdet.step.step_docstring(evt)
step_evt = sdet.step.evt(evt)
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