glean/docs/user/metrics/quantity.md

Quantity

Used to record a single non-negative integer value. For example, the width of the display in pixels.

Quantities are only available for metrics that come from Gecko.

Configuration

Say you're adding a new quantity for the width of the display in pixels. First you need to add an entry for the quantity to the metrics.yaml file:

gfx:
  display_width:
    type: quantity
    description: >
      The width of the display, in pixels.      
    unit: pixels
    gecko_datapoint: DISPLAY_W_PIXELS
    ...

Note that quantities have a required unit parameter, which is a free-form string for documentation purposes.

API

import org.mozilla.yourApplication.GleanMetrics.Gfx

Gfx.displayWidth.set(width)

There are test APIs available too:

import org.mozilla.yourApplication.GleanMetrics.Gfx

// Was anything recorded?
assertTrue(Gfx.displayWidth.testHasValue())
// Does the quantity have the expected value?
assertEquals(6, Gfx.displayWidth.testGetValue())

Limits

• Quantities must be non-negative integers.

• Quantities are only available for metrics that come from Gecko.

Examples

• What is the width of the display, in pixels?

Recorded errors

• invalid_value: If a negative value is passed in.

Reference

• Kotlin API docs