# `URP.Telemetry`

Telemetry events emitted by URP.

## Events

### `[:urp, :call, :stop]`

Emitted after every pool checkout completes (all operations go through
`URP.Pool.do_checkout/5`).

#### Measurements (in `:native` time units)

| Key | Description |
|---|---|
| `:total_time` | Wall time from checkout request to work completion |
| `:queue_time` | Time spent waiting for a pool connection |
| `:service_time` | Time spent doing work on the connection |

Use `System.convert_time_unit/3` to convert to milliseconds or
microseconds:

    System.convert_time_unit(queue_time, :native, :millisecond)

#### Metadata

| Key | Type | Description |
|---|---|---|
| `:operation` | `atom` | The operation performed (e.g. `:convert`, `:version`, `:filters`) |
| `:pool` | `term` | The pool name or pid |
| `:result` | `:ok \| :error` | Whether the operation succeeded |

## Example handler

    :telemetry.attach(
      "urp-logger",
      [:urp, :call, :stop],
      fn event, measurements, metadata, _config ->
        total_ms = System.convert_time_unit(measurements.total_time, :native, :millisecond)
        queue_ms = System.convert_time_unit(measurements.queue_time, :native, :millisecond)

        Logger.info(
          "[URP] #{metadata.operation} #{metadata.result} " <>
            "total=#{total_ms}ms queue=#{queue_ms}ms"
        )
      end,
      nil
    )

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*Consult [api-reference.md](api-reference.md) for complete listing*