feat(metrics): prototype experimental advice support

CHANGELOG.md

@@ -11,6 +11,8 @@ For experimental package changes, see the [experimental CHANGELOG](experimental/
 
 ### :rocket: (Enhancement)
 
+* feat(metrics): prototype experimental advice support [#3876](https://github.com/open-telemetry/opentelemetry-js/pull/3876) @legendecas
+
 ### :bug: (Bug Fix)
 
 ### :books: (Refine Doc)

api/CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 
 ## Unreleased
 
+### :rocket: (Enhancement)
+
+* feat(metrics): prototype experimental advice support [#3876](https://github.com/open-telemetry/opentelemetry-js/pull/3876) @legendecas
+
 ## 1.6.0
 
 ### :bug: (Bug Fix)

api/src/index.ts

@@ -51,6 +51,7 @@ export {
   ObservableUpDownCounter,
   UpDownCounter,
   BatchObservableCallback,
+  MetricAdvice,
   MetricAttributes,
   MetricAttributeValue,
   ObservableCallback,

api/src/metrics/Metric.ts

@@ -18,6 +18,18 @@ import { Attributes, AttributeValue } from '../common/Attributes';
 import { Context } from '../context/types';
 import { BatchObservableResult, ObservableResult } from './ObservableResult';
 
+/**
+ * Advisory options influencing aggregation configuration parameters.
+ * @experimental
+ */
+export interface MetricAdvice {
+  /**
+   * Hint the explicit bucket boundaries for SDK if the metric is been
+   * aggregated with a HistogramAggregator.
+   */
+  explicitBucketBoundaries?: number[];
+}
+
 /**
  * Options needed for metric creation
  */
@@ -39,6 +51,12 @@ export interface MetricOptions {
    * @default {@link ValueType.DOUBLE}
    */
   valueType?: ValueType;
+
+  /**
+   * The advice influencing aggregation configuration parameters.
+   * @experimental
+   */
+  advice?: MetricAdvice;
 }
 
 /** The Type of value. It describes how the data is reported. */

packages/sdk-metrics/src/InstrumentDescriptor.ts

@@ -14,7 +14,12 @@
  * limitations under the License.
  */
 
-import { MetricOptions, ValueType, diag } from '@opentelemetry/api';
+import {
+  MetricAdvice,
+  MetricOptions,
+  ValueType,
+  diag,
+} from '@opentelemetry/api';
 import { View } from './view/View';
 import { equalsCaseInsensitive } from './utils';
 
@@ -31,14 +36,21 @@ export enum InstrumentType {
 }
 
 /**
- * An interface describing the instrument.
+ * An internal interface describing the instrument.
+ *
+ * This is intentionally distinguished from the public MetricDescriptor (a.k.a. InstrumentDescriptor)
+ * which may not contains internal fields like metric advice.
  */
 export interface InstrumentDescriptor {
   readonly name: string;
   readonly description: string;
   readonly unit: string;
   readonly type: InstrumentType;
   readonly valueType: ValueType;
+  /**
+   * @experimental
+   */
+  readonly advice: MetricAdvice;
 }
 
 export function createInstrumentDescriptor(
@@ -57,6 +69,7 @@ export function createInstrumentDescriptor(
     description: options?.description ?? '',
     unit: options?.unit ?? '',
     valueType: options?.valueType ?? ValueType.DOUBLE,
+    advice: options?.advice ?? {},
   };
 }
 
@@ -70,6 +83,7 @@ export function createInstrumentDescriptorWithView(
     type: instrument.type,
     unit: instrument.unit,
     valueType: instrument.valueType,
+    advice: instrument.advice,
   };
 }
 

packages/sdk-metrics/src/ObservableResult.ts

@@ -24,7 +24,6 @@ import {
 } from '@opentelemetry/api';
 import { AttributeHashMap } from './state/HashMap';
 import { isObservableInstrument, ObservableInstrument } from './Instruments';
-import { InstrumentDescriptor } from '.';
 
 /**
  * The class implements {@link ObservableResult} interface.
@@ -35,24 +34,24 @@ export class ObservableResultImpl implements ObservableResult {
    */
   _buffer = new AttributeHashMap<number>();
 
-  constructor(private _descriptor: InstrumentDescriptor) {}
+  constructor(
+    private _instrumentName: string,
+    private _valueType: ValueType
+  ) {}
 
   /**
    * Observe a measurement of the value associated with the given attributes.
    */
   observe(value: number, attributes: MetricAttributes = {}): void {
     if (typeof value !== 'number') {
       diag.warn(
-        `non-number value provided to metric ${this._descriptor.name}: ${value}`
+        `non-number value provided to metric ${this._instrumentName}: ${value}`
       );
       return;
     }
-    if (
-      this._descriptor.valueType === ValueType.INT &&
-      !Number.isInteger(value)
-    ) {
+    if (this._valueType === ValueType.INT && !Number.isInteger(value)) {
       diag.warn(
-        `INT value type cannot accept a floating-point value for ${this._descriptor.name}, ignoring the fractional digits.`
+        `INT value type cannot accept a floating-point value for ${this._instrumentName}, ignoring the fractional digits.`
       );
       value = Math.trunc(value);
       // ignore non-finite values.

packages/sdk-metrics/src/aggregator/Drop.ts

@@ -16,8 +16,7 @@
 
 import { HrTime } from '@opentelemetry/api';
 import { AggregationTemporality } from '../export/AggregationTemporality';
-import { MetricData } from '../export/MetricData';
-import { InstrumentDescriptor } from '../InstrumentDescriptor';
+import { MetricData, MetricDescriptor } from '../export/MetricData';
 import { Maybe } from '../utils';
 import { AggregatorKind, Aggregator, AccumulationRecord } from './types';
 
@@ -38,7 +37,7 @@ export class DropAggregator implements Aggregator<undefined> {
   }
 
   toMetricData(
-    _descriptor: InstrumentDescriptor,
+    _descriptor: MetricDescriptor,
     _aggregationTemporality: AggregationTemporality,
     _accumulationByAttributes: AccumulationRecord<undefined>[],
     _endTime: HrTime

packages/sdk-metrics/src/aggregator/ExponentialHistogram.ts

@@ -24,9 +24,10 @@ import {
 import {
   DataPointType,
   ExponentialHistogramMetricData,
+  MetricDescriptor,
 } from '../export/MetricData';
 import { diag, HrTime } from '@opentelemetry/api';
-import { InstrumentDescriptor, InstrumentType } from '../InstrumentDescriptor';
+import { InstrumentType } from '../InstrumentDescriptor';
 import { Maybe } from '../utils';
 import { AggregationTemporality } from '../export/AggregationTemporality';
 import { Buckets } from './exponential-histogram/Buckets';
@@ -555,7 +556,7 @@ export class ExponentialHistogramAggregator
   }
 
   toMetricData(
-    descriptor: InstrumentDescriptor,
+    descriptor: MetricDescriptor,
     aggregationTemporality: AggregationTemporality,
     accumulationByAttributes: AccumulationRecord<ExponentialHistogramAccumulation>[],
     endTime: HrTime

packages/sdk-metrics/src/aggregator/Histogram.ts

@@ -20,9 +20,13 @@ import {
   Aggregator,
   AggregatorKind,
 } from './types';
-import { DataPointType, HistogramMetricData } from '../export/MetricData';
+import {
+  DataPointType,
+  HistogramMetricData,
+  MetricDescriptor,
+} from '../export/MetricData';
 import { HrTime } from '@opentelemetry/api';
-import { InstrumentDescriptor, InstrumentType } from '../InstrumentDescriptor';
+import { InstrumentType } from '../InstrumentDescriptor';
 import { binarySearchLB, Maybe } from '../utils';
 import { AggregationTemporality } from '../export/AggregationTemporality';
 
@@ -207,7 +211,7 @@ export class HistogramAggregator implements Aggregator<HistogramAccumulation> {
   }
 
   toMetricData(
-    descriptor: InstrumentDescriptor,
+    descriptor: MetricDescriptor,
     aggregationTemporality: AggregationTemporality,
     accumulationByAttributes: AccumulationRecord<HistogramAccumulation>[],
     endTime: HrTime

packages/sdk-metrics/src/aggregator/LastValue.ts

@@ -23,8 +23,11 @@ import {
 } from './types';
 import { HrTime } from '@opentelemetry/api';
 import { millisToHrTime, hrTimeToMicroseconds } from '@opentelemetry/core';
-import { DataPointType, GaugeMetricData } from '../export/MetricData';
-import { InstrumentDescriptor } from '../InstrumentDescriptor';
+import {
+  DataPointType,
+  GaugeMetricData,
+  MetricDescriptor,
+} from '../export/MetricData';
 import { Maybe } from '../utils';
 import { AggregationTemporality } from '../export/AggregationTemporality';
 
@@ -103,7 +106,7 @@ export class LastValueAggregator implements Aggregator<LastValueAccumulation> {
   }
 
   toMetricData(
-    descriptor: InstrumentDescriptor,
+    descriptor: MetricDescriptor,
     aggregationTemporality: AggregationTemporality,
     accumulationByAttributes: AccumulationRecord<LastValueAccumulation>[],
     endTime: HrTime

packages/sdk-metrics/src/aggregator/Sum.ts

@@ -22,8 +22,11 @@ import {
   AccumulationRecord,
 } from './types';
 import { HrTime } from '@opentelemetry/api';
-import { DataPointType, SumMetricData } from '../export/MetricData';
-import { InstrumentDescriptor } from '../InstrumentDescriptor';
+import {
+  DataPointType,
+  MetricDescriptor,
+  SumMetricData,
+} from '../export/MetricData';
 import { Maybe } from '../utils';
 import { AggregationTemporality } from '../export/AggregationTemporality';
 
@@ -109,7 +112,7 @@ export class SumAggregator implements Aggregator<SumAccumulation> {
   }
 
   toMetricData(
-    descriptor: InstrumentDescriptor,
+    descriptor: MetricDescriptor,
     aggregationTemporality: AggregationTemporality,
     accumulationByAttributes: AccumulationRecord<SumAccumulation>[],
     endTime: HrTime

packages/sdk-metrics/src/aggregator/types.ts

@@ -16,8 +16,7 @@
 
 import { HrTime, MetricAttributes } from '@opentelemetry/api';
 import { AggregationTemporality } from '../export/AggregationTemporality';
-import { MetricData } from '../export/MetricData';
-import { InstrumentDescriptor } from '../InstrumentDescriptor';
+import { MetricData, MetricDescriptor } from '../export/MetricData';
 import { Maybe } from '../utils';
 
 /** The kind of aggregator. */
@@ -128,14 +127,14 @@ export interface Aggregator<T> {
   /**
    * Returns the {@link MetricData} that this {@link Aggregator} will produce.
    *
-   * @param descriptor the metric instrument descriptor.
+   * @param descriptor the metric descriptor.
    * @param aggregationTemporality the temporality of the resulting {@link MetricData}
    * @param accumulationByAttributes the array of attributes and accumulation pairs.
    * @param endTime the end time of the metric data.
    * @return the {@link MetricData} that this {@link Aggregator} will produce.
    */
   toMetricData(
-    descriptor: InstrumentDescriptor,
+    descriptor: MetricDescriptor,
     aggregationTemporality: AggregationTemporality,
     accumulationByAttributes: AccumulationRecord<T>[],
     endTime: HrTime

packages/sdk-metrics/src/export/MetricData.ts

@@ -14,18 +14,30 @@
  * limitations under the License.
  */
 
-import { HrTime, MetricAttributes } from '@opentelemetry/api';
+import { HrTime, MetricAttributes, ValueType } from '@opentelemetry/api';
 import { InstrumentationScope } from '@opentelemetry/core';
 import { IResource } from '@opentelemetry/resources';
-import { InstrumentDescriptor } from '../InstrumentDescriptor';
+import { InstrumentType } from '../InstrumentDescriptor';
 import { AggregationTemporality } from './AggregationTemporality';
 import { Histogram, ExponentialHistogram } from '../aggregator/types';
 
+export interface MetricDescriptor {
+  readonly name: string;
+  readonly description: string;
+  readonly unit: string;
+  /**
+   * @deprecated exporter should avoid depending on the type of the instrument
+   * as their resulting aggregator can be re-mapped with views.
+   */
+  readonly type: InstrumentType;
+  readonly valueType: ValueType;
+}
+
 /**
  * Basic metric data fields.
  */
 interface BaseMetricData {
-  readonly descriptor: InstrumentDescriptor;
+  readonly descriptor: MetricDescriptor;
   readonly aggregationTemporality: AggregationTemporality;
   /**
    * DataPointType of the metric instrument.

packages/sdk-metrics/src/index.ts

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+import { MetricDescriptor } from './export/MetricData';
+
 export {
   Sum,
   LastValue,
@@ -38,6 +40,7 @@ export {
   ResourceMetrics,
   ScopeMetrics,
   MetricData,
+  MetricDescriptor,
   CollectionResult,
 } from './export/MetricData';
 
@@ -56,7 +59,11 @@ export { ConsoleMetricExporter } from './export/ConsoleMetricExporter';
 
 export { MetricCollectOptions, MetricProducer } from './export/MetricProducer';
 
-export { InstrumentDescriptor, InstrumentType } from './InstrumentDescriptor';
+export { InstrumentType } from './InstrumentDescriptor';
+/**
+ * @deprecated Use {@link MetricDescriptor} instead.
+ */
+export type InstrumentDescriptor = MetricDescriptor;
 
 export { MeterProvider, MeterProviderOptions } from './MeterProvider';
 

packages/sdk-metrics/src/state/MetricStorage.ts

@@ -54,6 +54,7 @@ export abstract class MetricStorage {
         description: description,
         valueType: this._instrumentDescriptor.valueType,
         unit: this._instrumentDescriptor.unit,
+        advice: this._instrumentDescriptor.advice,
       }
     );
   }

packages/sdk-metrics/src/state/ObservableRegistry.ts

@@ -144,7 +144,10 @@ export class ObservableRegistry {
 
   private _observeCallbacks(observationTime: HrTime, timeoutMillis?: number) {
     return this._callbacks.map(async ({ callback, instrument }) => {
-      const observableResult = new ObservableResultImpl(instrument._descriptor);
+      const observableResult = new ObservableResultImpl(
+        instrument._descriptor.name,
+        instrument._descriptor.valueType
+      );
       let callPromise: Promise<void> = Promise.resolve(
         callback(observableResult)
       );

packages/sdk-metrics/src/view/Aggregation.ts

@@ -184,6 +184,11 @@ export class DefaultAggregation extends Aggregation {
         return LAST_VALUE_AGGREGATION;
       }
       case InstrumentType.HISTOGRAM: {
+        if (instrument.advice.explicitBucketBoundaries) {
+          return new ExplicitBucketHistogramAggregation(
+            instrument.advice.explicitBucketBoundaries
+          );
+        }
         return HISTOGRAM_AGGREGATION;
       }
     }