# Metrics Name Mapping

This directory contains generic logic and configuration schemas for renaming
and mapping metrics emitted by specific subprocesses before they are merged
into the browser's global metrics logs.

See [the design doc][1] and [the configuration schema][2].

[1]: https://docs.google.com/document/d/1sYiMun4Sif9BpoWpQv6Ks6SFjPri58qFgRNwSP7RrZU/edit?resourcekey=0-1o82VfCU2bfN0pkXdnF8ag
[2]: https://docs.google.com/document/d/1SudIQmC_nrfyDzqXcDDDZP6ZN596FFm56rpFdoJnHFs/edit?resourcekey=0-JZy13P2VyfvbrTSNzWD27w&tab=t.0

## Configuration

The generic mapping strategy utilizes a `MetricsNameMapper` class initialized
with a Base-64 encoded protobuf string representing the
`MetricsNameMappingConfiguration`.

This configuration defines a `rules` array in `metrics_name_mapping.proto`
which dictates whether a strictly matching histogram string should be dropped or
mapped to a `new_metric_name`.

The `MetricsNameMapper` evaluator is called dynamically by the
`SubprocessMetricsProvider` when parsing and merging metric allocation streams
from child processes.