Bandera.Telemetry (bandera v0.1.0)

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Telemetry events for Bandera.

All events are prefixed with :bandera. The hot read path uses lightweight point-in-time events; writes and introspection use span events.

Point-in-time events (measurement: %{system_time})

  • [:bandera, :enabled?] — a flag was checked. Metadata: %{flag_name, options, result}.
  • [:bandera, :persistence, :get] — a flag was read from the persistent adapter. Emitted ONLY on a cache miss (a cache hit does not read the adapter). Metadata: %{flag_name}.

Span events (…:start / …:stop with :duration / …:exception)

Emitted via :telemetry.span/3.

:stop/:exception events carry the start metadata (e.g. flag_name, options) merged with any extra stop fields (e.g. result).

  • [:bandera, :enable], [:bandera, :disable], [:bandera, :clear] — public API writes. Start metadata %{flag_name, options}; stop metadata %{result}.
  • [:bandera, :persistence, :put], [:bandera, :persistence, :delete] — store writes. Start metadata %{flag_name, gate} (gate where applicable).
  • [:bandera, :persistence, :all_flags], [:bandera, :persistence, :all_flag_names].

Summary

Functions

event(prefix, metadata)

Emit a point-in-time :telemetry event under [:bandera | prefix] with a system_time measurement.

span(prefix, metadata, fun)

Run fun inside a :telemetry span under [:bandera | prefix]. fun returns {result, extra_stop_metadata} and the function's result is returned.

Functions

event(prefix, metadata)

@spec event([atom()], map()) :: :ok

Emit a point-in-time :telemetry event under [:bandera | prefix] with a system_time measurement.

span(prefix, metadata, fun)

@spec span([atom()], map(), (-> {result, map()})) :: result when result: var

Run fun inside a :telemetry span under [:bandera | prefix]. fun returns {result, extra_stop_metadata} and the function's result is returned.

The :stop event carries the start metadata merged with extra_stop_metadata (stop fields win on key conflict). The :exception event carries the start metadata with kind, reason, and stacktrace added by :telemetry automatically (the function does not run to completion on a raise).