Summary:
This diff implements TelemetryController, a small tool that can be used to instrument mounting transactions. It abstracts the logic of merging telemetry data of multiple transactions in a thread-safe manner.
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: sammy-SC
Differential Revision: D22490580
fbshipit-source-id: 3f3425b88d38fddb555c1390fd8f1ff3ef1c475a