feat(api-metrics): async instruments spec compliance

examples/metrics/metrics/observer.js

@@ -23,14 +23,14 @@ const meter = new MeterProvider({
   interval: 2000,
 }).getMeter('example-meter');
 
-meter.createObservableGauge('cpu_core_usage', {
-  description: 'Example of a sync observable gauge with callback',
-}, async (observableResult) => { // this callback is called once per each interval
+meter.createObservableGauge('cpu_core_usage', async (observableResult) => { // this callback is called once per each interval
   await new Promise((resolve) => {
     setTimeout(() => { resolve(); }, 50);
   });
   observableResult.observe(getRandomValue(), { core: '1' });
   observableResult.observe(getRandomValue(), { core: '2' });
+}, {
+  description: 'Example of a sync observable gauge with callback',
 });
 
 function getRandomValue() {

experimental/packages/opentelemetry-api-metrics/src/NoopMeter.ts

@@ -27,7 +27,6 @@ import {
   ObservableUpDownCounter,
 } from './types/Metric';
 import { ObservableResult } from './types/ObservableResult';
-import { Observation } from './types/Observation';
 
 /**
  * NoopMeter is a noop implementation of the {@link Meter} interface. It reuses
@@ -66,41 +65,41 @@ export class NoopMeter implements Meter {
   /**
    * Returns a constant noop observable gauge.
    * @param name the name of the metric.
+   * @param callback the observable gauge callback
    * @param [options] the metric options.
-   * @param [callback] the observable gauge callback
    */
   createObservableGauge(
     _name: string,
+    _callback: (observableResult: ObservableResult) => void,
     _options?: MetricOptions,
-    _callback?: (observableResult: ObservableResult) => void
   ): ObservableGauge {
     return NOOP_OBSERVABLE_GAUGE_METRIC;
   }
 
   /**
    * Returns a constant noop observable counter.
    * @param name the name of the metric.
+   * @param callback the observable counter callback
    * @param [options] the metric options.
-   * @param [callback] the observable counter callback
    */
   createObservableCounter(
     _name: string,
+    _callback: (observableResult: ObservableResult) => void,
     _options?: MetricOptions,
-    _callback?: (observableResult: ObservableResult) => void
   ): ObservableCounter {
     return NOOP_OBSERVABLE_COUNTER_METRIC;
   }
 
   /**
    * Returns a constant noop up down observable counter.
    * @param name the name of the metric.
+   * @param callback the up down observable counter callback
    * @param [options] the metric options.
-   * @param [callback] the up down observable counter callback
    */
   createObservableUpDownCounter(
     _name: string,
+    _callback: (observableResult: ObservableResult) => void,
     _options?: MetricOptions,
-    _callback?: (observableResult: ObservableResult) => void
   ): ObservableUpDownCounter {
     return NOOP_OBSERVABLE_UP_DOWN_COUNTER_METRIC;
   }
@@ -120,14 +119,7 @@ export class NoopHistogramMetric extends NoopMetric implements Histogram {
   record(_value: number, _labels: Labels): void {}
 }
 
-export class NoopObservableBaseMetric extends NoopMetric implements ObservableBase {
-  observation(): Observation {
-    return {
-      observable: this as ObservableBase,
-      value: 0,
-    };
-  }
-}
+export class NoopObservableBaseMetric extends NoopMetric implements ObservableBase {}
 
 export const NOOP_METER = new NoopMeter();
 

experimental/packages/opentelemetry-api-metrics/src/index.ts

@@ -19,7 +19,6 @@ export * from './NoopMeterProvider';
 export * from './types/Meter';
 export * from './types/MeterProvider';
 export * from './types/Metric';
-export * from './types/Observation';
 export * from './types/ObservableResult';
 
 import { MetricsAPI } from './api/metrics';

experimental/packages/opentelemetry-api-metrics/src/types/Meter.ts

@@ -81,36 +81,36 @@ export interface Meter {
   /**
    * Creates a new `ObservableGauge` metric.
    * @param name the name of the metric.
+   * @param callback the observable callback
    * @param [options] the metric options.
-   * @param [callback] the observable callback
    */
   createObservableGauge(
     name: string,
-    options?: MetricOptions,
-    callback?: (observableResult: ObservableResult) => void
+    callback: (observableResult: ObservableResult) => void,
+    options?: MetricOptions
   ): ObservableGauge;
 
   /**
    * Creates a new `ObservableCounter` metric.
    * @param name the name of the metric.
+   * @param callback the observable callback
    * @param [options] the metric options.
-   * @param [callback] the observable callback
    */
   createObservableCounter(
     name: string,
-    options?: MetricOptions,
-    callback?: (observableResult: ObservableResult) => void
+    callback: (observableResult: ObservableResult) => void,
+    options?: MetricOptions
   ): ObservableCounter;
 
   /**
    * Creates a new `ObservableUpDownCounter` metric.
    * @param name the name of the metric.
+   * @param callback the observable callback
    * @param [options] the metric options.
-   * @param [callback] the observable callback
    */
   createObservableUpDownCounter(
     name: string,
-    options?: MetricOptions,
-    callback?: (observableResult: ObservableResult) => void
+    callback: (observableResult: ObservableResult) => void,
+    options?: MetricOptions
   ): ObservableUpDownCounter;
 }

experimental/packages/opentelemetry-api-metrics/src/types/Metric.ts

@@ -14,10 +14,6 @@
  * limitations under the License.
  */
 
-import {
-  Observation,
-} from './Observation';
-
 /**
  * Options needed for metric creation
  */
@@ -112,13 +108,10 @@ export interface Histogram {
   record(value: number, labels?: Labels): void;
 }
 
+// ObservableBase has to be an Object but for now there is no field or method
+// declared.
 /** Base interface for the Observable metrics. */
-export interface ObservableBase {
-  observation: (
-    value: number,
-    labels?: Labels,
-  ) => Observation;
-}
+export type ObservableBase = Record<never, never>;
 
 /** Base interface for the ObservableGauge metrics. */
 export type ObservableGauge = ObservableBase;

experimental/packages/opentelemetry-api-metrics/src/types/ObservableResult.ts

@@ -20,5 +20,5 @@ import { Labels } from './Metric';
  * Interface that is being used in callback function for Observable Metric
  */
 export interface ObservableResult {
-  observe(value: number, labels: Labels): void;
+  observe(value: number, labels?: Labels): void;
 }

experimental/packages/opentelemetry-exporter-metrics-otlp-grpc/test/metricsHelper.ts

@@ -60,11 +60,11 @@ export function mockObservableGauge(
     meter['_metrics'].get(name) ||
     meter.createObservableGauge(
       name,
+      callback,
       {
         description: 'sample observable gauge description',
         valueType: ValueType.DOUBLE,
-      },
-      callback
+      }
     );
   metric.clear();
   metric.bind({});

experimental/packages/opentelemetry-exporter-metrics-otlp-http/test/metricsHelper.ts

@@ -83,11 +83,11 @@ export function mockObservableGauge(
     meter['_metrics'].get(name) ||
     meter.createObservableGauge(
       name,
+      callback,
       {
         description: 'sample observable gauge description',
         valueType: ValueType.DOUBLE,
-      },
-      callback
+      }
     );
   metric.clear();
   metric.bind({});
@@ -102,11 +102,11 @@ export function mockObservableCounter(
     meter['_metrics'].get(name) ||
     meter.createObservableCounter(
       name,
+      callback,
       {
         description: 'sample observable counter description',
         valueType: ValueType.DOUBLE,
-      },
-      callback
+      }
     );
   metric.clear();
   metric.bind({});
@@ -121,11 +121,11 @@ export function mockObservableUpDownCounter(
     meter['_metrics'].get(name) ||
     meter.createObservableUpDownCounter(
       name,
+      callback,
       {
         description: 'sample observable up down counter description',
         valueType: ValueType.DOUBLE,
-      },
-      callback
+      }
     );
   metric.clear();
   metric.bind({});

experimental/packages/opentelemetry-exporter-metrics-otlp-proto/test/metricsHelper.ts

@@ -59,11 +59,11 @@ export function mockObservableGauge(
     meter['_metrics'].get(name) ||
     meter.createObservableGauge(
       name,
+      callback,
       {
         description: 'sample observable gauge description',
         valueType: ValueType.DOUBLE,
-      },
-      callback
+      }
     );
   metric.clear();
   metric.bind({});

experimental/packages/opentelemetry-exporter-prometheus/test/PrometheusExporter.test.ts

@@ -286,14 +286,14 @@ describe('PrometheusExporter', () => {
 
       meter.createObservableGauge(
         'metric_observable_gauge',
-        {
-          description: 'a test description',
-        },
         (observableResult: ObservableResult) => {
           observableResult.observe(getCpuUsage(), {
             pid: String(123),
             core: '1',
           });
+        },
+        {
+          description: 'a test description',
         }
       );
 
@@ -477,13 +477,13 @@ describe('PrometheusExporter', () => {
 
       meter.createObservableCounter(
         'metric_observable_counter',
-        {
-          description: 'a test description',
-        },
         (observableResult: ObservableResult) => {
           observableResult.observe(getValue(), {
             key1: 'labelValue1',
           });
+        },
+        {
+          description: 'a test description',
         }
       );
 
@@ -517,13 +517,13 @@ describe('PrometheusExporter', () => {
 
       meter.createObservableUpDownCounter(
         'metric_observable_up_down_counter',
-        {
-          description: 'a test description',
-        },
         (observableResult: ObservableResult) => {
           observableResult.observe(getValue(), {
             key1: 'labelValue1',
           });
+        },
+        {
+          description: 'a test description',
         }
       );
 

experimental/packages/opentelemetry-exporter-prometheus/test/PrometheusSerializer.test.ts

@@ -101,7 +101,6 @@ describe('PrometheusSerializer', () => {
         }).getMeter('test');
         const observableGauge = meter.createObservableGauge(
           'test',
-          {},
           observableResult => {
             observableResult.observe(1, labels);
           }
@@ -128,7 +127,6 @@ describe('PrometheusSerializer', () => {
         }).getMeter('test');
         const observableGauge = meter.createObservableGauge(
           'test',
-          {},
           observableResult => {
             observableResult.observe(1, labels);
           }
@@ -306,11 +304,11 @@ describe('PrometheusSerializer', () => {
         const processor = new PrometheusLabelsBatcher();
         const observableGauge = meter.createObservableGauge(
           'test',
-          {
-            description: 'foobar',
-          },
           observableResult => {
             observableResult.observe(1, labels);
+          },
+          {
+            description: 'foobar',
           }
         ) as ObservableGaugeMetric;
         await meter.collect();