1588451 - Do not ignore previously seen dynamic labels before Glean inits

Status: RESOLVED FIXED

(Data Platform and Tools :: Glean: SDK, defect, P3)

Description

[Alessio Placitelli [:Dexter]]

With bug 1588092, we made the glean-core implementation behave like the glean-ac undocumented behaviour to prevent startup crashes when using LabeledMetricType with dynamic labels before Glean inits.

When labeled metrics are used with dynamic labels before Glean inits, we ignore any previously persisted label. If someone where to use 16 new dynamic labels before Glean initializes, it would send 16 new labels even though we already stored 4 old ones in our database.

Comment 1

[Michael Droettboom [:mdroettboom]]

Part of what makes this hard is the overator overloading syntax, since the look up of the label happens syncronously and the recording happens asynchronously.

One solution there would be to (backward incompatibly) change the label recording syntax from labeledCounter["label"].add(1) to labeledCounter.add("label", 1). However, this will require new wrappers for each labeled metric type.

Or, there might be a way to make label lookup part of the deferred coroutine call somehow...