Telemetry events for FunWithFlags.

This module centralizes the emission of all Telemetry events for the package.

Events

The common prefix for all events is :fun_with_flags, followed by a logical scope (e.g. :persistence) and the event name.

Events are simple "point in time" events rather than span events (that is, there is no distinct :start and :stop events with a duration measurement).

Persistence

Events for CRUD operations on the persistent datastore.

All events contain the same measurement:

• system_time (integer), which is the current system time in the :native time unit. See :erlang.system_time/0.

Events:

• [:fun_with_flags, :persistence, :read], emitted when a flag is read from the DB. Crucially, this event is not emitted when the cache is enabled and there is a cache hit, and it's emitted only when retrieving a flag reads from the persistent datastore. Therefore, when the cache is disabled, this event is always emitted every time a flag is queried.

  Metadata:

  • flag_name (atom), the name of the flag being read.

• [:fun_with_flags, :persistence, :read_all_flags], emitted when all flags are read from the DB. No extra metadata.

• [:fun_with_flags, :persistence, :read_all_flag_names], emitted when all flags names are read from the DB. No extra metadata.

• [:fun_with_flags, :persistence, :write], emitted when writing a flag to the DB. In practive, what is written is one of the gates of the flag, which is always upserted.

  Metadata:

  • flag_name (atom), the name of the flag being written.
  • gate (FunWithFlags.Gate), the gate being upserted.

• [:fun_with_flags, :persistence, :delete_flag], emitted when an entire flag is deleted from the DB.

  Metadata:

  • flag_name (atom), the name of the flag being deleted.

• [:fun_with_flags, :persistence, :delete_gate], emitted when one of the flag's gates is deleted from the DB.

  Metadata:

  • flag_name (atom), the name of the flag whose gate is being deleted.
  • gate (FunWithFlags.Gate), the gate being deleted.

• [:fun_with_flags, :persistence, :reload], emitted when a flag is reloaded from the DB. This typically happens when the node has received a change notification for a flag, which results in the cache being invalidated and the flag being reloaded from the DB.

  Metadata:

  • flag_name (atom), the name of the flag being reloaded.

• [:fun_with_flags, :persistence, :error], emitted for erorrs in any of the above operations.

  Metadata:

  • error (any), the error that occurred. This is typically a string or any appropriate error term returned by the underlying persistence adapters.
  • original_event (atom), the name of the original event that failed, e.g. :read, :write, :delete_gate, etc.
  • flag_name (atom), the name of the flag being operated on, if supported by the original event.
  • gate (FunWithFlags.Gate), the gate being operated on, if supported by the original event.