ExDataSketch.Telemetry.Metrics (ExDataSketch v0.10.0)

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Ready-made Telemetry.Metrics definitions for every ExDataSketch telemetry event.

Pass all/1's result straight to a Telemetry.Metrics reporter (the Telemetry.Metrics.ConsoleReporter built into the :telemetry_metrics package, TelemetryMetricsPrometheus, TelemetryMetricsStatsd, or Phoenix LiveDashboard's own metrics page) instead of hand-writing a metric per event.

Usage

# In a Phoenix application's telemetry.ex:
def metrics do
  ExDataSketch.Telemetry.Metrics.all() ++ [
    # ... your application's own metrics
  ]
end

See ExDataSketch.Telemetry's moduledoc for the full event/measurement/ metadata table this module's metric list is derived from.

Coverage

Every event ExDataSketch.Telemetry.all_event_names/0 returns has at least one metric here: a summary for each numeric measurement it carries, or a counter (an event-occurrence count) when it carries none. [:ex_data_sketch, :stream, :reduce] is the only event with no measurements at all, so it is the only event that gets a counter purely for coverage; [:ex_data_sketch, :sketch, :ingest] additionally gets a counter alongside its duration/size_bytes summaries as a call-volume metric for the library's most common operation.

What is deliberately not a metric here

  • pipeline.accumulate's batch_size metadata is not a tag on any metric -- it is a per-call variable integer, and tagging by it would explode cardinality in a real reporter (StatsD, Prometheus). Build a custom metric with Telemetry.Metrics.summary/2 directly if you need it.
  • window.roll's oldest_age_ms is metadata describing the dropped slot's age, not a measurement in the :telemetry.execute/3 measurements map, so no Telemetry.Metrics definition can read it.
  • persistence.delete has no sketch_type tag: the sketch struct is already discarded by the time that event fires (see ExDataSketch.Telemetry's moduledoc).

Summary

Types

opts()

Options accepted by all/1.

Functions

all(opts \\ [])

Returns a Telemetry.Metrics definition for every event ExDataSketch.Telemetry.all_event_names/0 returns.

Types

opts()

@type opts() :: [{:prefix, String.t()}]

Options accepted by all/1.

Functions

all(opts \\ [])

@spec all(opts()) :: [Telemetry.Metrics.t()]

Returns a Telemetry.Metrics definition for every event ExDataSketch.Telemetry.all_event_names/0 returns.

Options

  • :prefix -- the dot-separated namespace prepended to every metric name (default: "ex_data_sketch"). Useful when running more than one ExDataSketch-backed component that needs distinct metric namespaces in a shared reporter. Only the metric's display name changes -- the underlying :telemetry event listened to is always the real, unprefixed [:ex_data_sketch, ...] event name, so metrics still fire regardless of this option.

Examples

iex> metrics = ExDataSketch.Telemetry.Metrics.all()
iex> length(metrics) > 0
true
iex> Enum.all?(metrics, fn m -> match?(%Telemetry.Metrics.Summary{}, m) or match?(%Telemetry.Metrics.Counter{}, m) end)
true

iex> metrics = ExDataSketch.Telemetry.Metrics.all(prefix: "my_app")
iex> [metric | _] = metrics
iex> String.starts_with?(metric.name |> Enum.join("."), "my_app.")
true