Otel.API.Metrics.Measurement (otel v0.2.0)

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A single numeric data point reported to the SDK (OTel metrics/api.md §Measurement, Status: Stable, L1278-L1287).

A Measurement encapsulates a numeric value plus its associated attributes (spec L1284-L1287). Observable (asynchronous) instrument callbacks return a list of Measurements — spec L441-L442 "Return a list (or tuple, generator, enumerator, etc.) of individual Measurement values". Synchronous recording APIs (Counter.add/4, Histogram.record/4, etc.) keep their (value, attributes) positional shape and do not use this struct — the callback-return path is the only place the handle flows across the API boundary as data.

opentelemetry-erlang has no dedicated Measurement record; it passes raw (value, attributes) tuples. We model every multi-field spec entity in this project as a defstruct so %Measurement{} patterns carry the shape through Dialyzer.

Construction

Callers construct instances with the %Measurement{...} struct literal directly:

%Otel.API.Metrics.Measurement{value: 42, attributes: %{"host" => "a"}}

This module provides no constructor function. A ceremonial new/2 was removed because it carried no runtime default (the attributes: %{} default already lives on defstruct), no spec enforcement (§Measurement has no MUST/SHOULD to wrap), and no validation (happy-path policy per .claude/rules/code-conventions.md). Contrast Event.new/3 (which supplies System.system_time(:nanosecond)) and Status.new/2 (which enforces spec L599 "Description MUST be IGNORED for :ok / :unset") — both carry real work. This module does not.

References

  • OTel Metrics API §Measurement: opentelemetry-specification/specification/metrics/api.md L1278-L1287
  • OTel Metrics API §Async callback shape: opentelemetry-specification/specification/metrics/api.md L441-L442

Summary

Types

primitive()
primitive_any()
t()

A Measurement struct (spec metrics/api.md §Measurement, L1278-L1287).

Types

primitive()

@type primitive() ::
  String.t() | {:bytes, binary()} | boolean() | integer() | float() | nil

primitive_any()

@type primitive_any() ::
  primitive() | [primitive_any()] | %{required(String.t()) => primitive_any()}

t()

@type t() :: %Otel.API.Metrics.Measurement{
  attributes: %{required(String.t()) => primitive_any()},
  value: number()
}

A Measurement struct (spec metrics/api.md §Measurement, L1278-L1287).

Fields:

  • value — the numeric data point. number/0 covers both integer and float variants the OTel metric instruments accept.
  • attributes — an %{String.t() => primitive_any()} map associated with the measurement. Values follow OTel attribute rules (primitives and homogeneous arrays; no maps, no heterogeneous arrays).