refactor(metrics): metrics provider implements controller

Metrics exporting requires a clear policy about when to export. While
MetricsProvider holds all meters created, it can act as a Controller
role to integrate better export strategies like pulling.

getting-started/ts-example/monitoring.ts

@@ -1,4 +1,4 @@
-import { MeterProvider } from '@opentelemetry/metrics';
+import { PushController } from '@opentelemetry/metrics';
 import { Metric, BoundCounter } from '@opentelemetry/api';
 import { PrometheusExporter } from '@opentelemetry/exporter-prometheus';
 
@@ -11,7 +11,7 @@ const exporter = new PrometheusExporter(
   },
 );
 
-const meter = new MeterProvider({
+const meter = new PushController({
   exporter,
   interval: 1000,
 }).getMeter('example-ts');

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

@@ -19,7 +19,7 @@ import {
   CounterMetric,
   CounterSumAggregator,
   Meter,
-  MeterProvider,
+  PushController,
   ObserverMetric,
   Point,
 } from '@opentelemetry/metrics';
@@ -189,7 +189,7 @@ describe('PrometheusExporter', () => {
 
     beforeEach(done => {
       exporter = new PrometheusExporter();
-      meter = new MeterProvider().getMeter('test-prometheus');
+      meter = new PushController().getMeter('test-prometheus');
       exporter.startServer(done);
     });
 
@@ -418,7 +418,7 @@ describe('PrometheusExporter', () => {
     let exporter: PrometheusExporter | undefined;
 
     beforeEach(() => {
-      meter = new MeterProvider().getMeter('test-prometheus');
+      meter = new PushController().getMeter('test-prometheus');
       counter = meter.createCounter('counter') as CounterMetric;
       counter.bind({ key1: 'labelValue1' }).add(10);
     });

packages/opentelemetry-metrics/README.md

@@ -19,10 +19,10 @@ npm install --save @opentelemetry/metrics
 Choose this kind of metric when the value is a quantity, the sum is of primary interest, and the event count and value distribution are not of primary interest. Counters are defined as `Monotonic = true` by default, meaning that positive values are expected.
 
 ```js
-const { MeterProvider } = require('@opentelemetry/metrics');
+const { PushController } = require('@opentelemetry/metrics');
 
 // Initialize the Meter to capture measurements in various ways.
-const meter = new MeterProvider().getMeter('your-meter-name');
+const meter = new PushController().getMeter('your-meter-name');
 
 const counter = meter.createCounter('metric_name', {
   labelKeys: ['pid'],
@@ -41,10 +41,10 @@ boundCounter.add(10);
 Choose this kind of metric when only last value is important without worry about aggregation
 
 ```js
-const { MeterProvider, MetricObservable } = require('@opentelemetry/metrics');
+const { PushController, MetricObservable } = require('@opentelemetry/metrics');
 
 // Initialize the Meter to capture measurements in various ways.
-const meter = new MeterProvider().getMeter('your-meter-name');
+const meter = new PushController().getMeter('your-meter-name');
 
 const observer = meter.createObserver('metric_name', {
   labelKeys: ['pid', 'core'],

packages/opentelemetry-metrics/src/Meter.ts

@@ -26,8 +26,6 @@ import {
   MeterConfig,
 } from './types';
 import { Batcher, UngroupedBatcher } from './export/Batcher';
-import { PushController } from './export/Controller';
-import { NoopExporter } from './export/NoopExporter';
 
 /**
  * Meter is an implementation of the {@link Meter} interface.
@@ -45,10 +43,6 @@ export class Meter implements api.Meter {
     this._logger = config.logger || new ConsoleLogger(config.logLevel);
     this._batcher = config.batcher ?? new UngroupedBatcher();
     this._resource = config.resource || Resource.createTelemetrySDKResource();
-    // start the push controller
-    const exporter = config.exporter || new NoopExporter();
-    const interval = config.interval;
-    new PushController(this, exporter, interval);
   }
 
   /**

packages/opentelemetry-metrics/src/export/Controller.ts

@@ -14,36 +14,27 @@
  * limitations under the License.
  */
 
-import { ExportResult, unrefTimer } from '@opentelemetry/core';
+import { ExportResult } from '@opentelemetry/core';
 import { Meter } from '../Meter';
 import { MetricExporter } from './types';
+import { Batcher } from './Batcher';
 
-const DEFAULT_EXPORT_INTERVAL = 60_000;
-
-export class Controller {}
-
-/** Controller organizes a periodic push of metric data. */
-export class PushController extends Controller {
-  private _timer: NodeJS.Timeout;
+export abstract class Controller {
+  protected readonly _meters: Map<string, Meter> = new Map();
 
   constructor(
-    private readonly _meter: Meter,
-    private readonly _exporter: MetricExporter,
-    interval: number = DEFAULT_EXPORT_INTERVAL
-  ) {
-    super();
-    this._timer = setInterval(() => {
-      this._collect();
-    }, interval);
-    unrefTimer(this._timer);
-  }
+    protected readonly _batcher: Batcher,
+    protected readonly _exporter: MetricExporter
+  ) {}
 
-  private _collect() {
-    this._meter.collect();
-    this._exporter.export(this._meter.getBatcher().checkPointSet(), result => {
-      if (result !== ExportResult.SUCCESS) {
-        // @todo: log error
-      }
+  protected collect() {
+    for (const meter of this._meters.values()) {
+      meter.collect();
+    }
+    this._exporter.export(this._batcher.checkPointSet(), result => {
+      this.onExportResult(result);
     });
   }
+
+  protected abstract onExportResult(result: ExportResult): void;
 }

packages/opentelemetry-metrics/src/export/controllers/PushController.ts

@@ -0,0 +1,73 @@
+/*!
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { ConsoleLogger, ExportResult, unrefTimer } from '@opentelemetry/core';
+import * as api from '@opentelemetry/api';
+import { Resource } from '@opentelemetry/resources';
+import { Meter } from '../../';
+import { DEFAULT_CONFIG, MeterConfig } from '../../types';
+import { PushControllerConfig } from './types';
+import { NoopExporter } from '../NoopExporter';
+import { UngroupedBatcher } from '../Batcher';
+import { Controller } from '../Controller';
+
+const DEFAULT_EXPORT_INTERVAL = 60_000;
+
+/**
+ * This class represents a meter provider collecting metric instrument values periodically.
+ */
+export class PushController extends Controller implements api.MeterProvider {
+  private _timer: NodeJS.Timeout;
+
+  readonly resource: Resource = Resource.createTelemetrySDKResource();
+  readonly logger: api.Logger;
+
+  constructor(private _config: PushControllerConfig = DEFAULT_CONFIG) {
+    super(
+      _config.batcher ?? new UngroupedBatcher(),
+      _config.exporter ?? new NoopExporter()
+    );
+    this.logger = _config.logger ?? new ConsoleLogger(_config.logLevel);
+
+    this._timer = setInterval(() => {
+      this.collect();
+    }, _config.interval ?? DEFAULT_EXPORT_INTERVAL);
+    unrefTimer(this._timer);
+  }
+
+  /**
+   * Returns a Meter, creating one if one with the given name and version is not already created
+   *
+   * @returns Meter A Meter with the given name and version
+   */
+  getMeter(name: string, version = '*', config?: MeterConfig): Meter {
+    const key = `${name}@${version}`;
+    if (!this._meters.has(key)) {
+      this._meters.set(key, new Meter(config || this._config));
+    }
+
+    return this._meters.get(key)!;
+  }
+
+  /**
+   * @implements Controller.onExportResult
+   */
+  protected onExportResult(result: ExportResult): void {
+    if (result !== ExportResult.SUCCESS) {
+      // @todo: log error
+    }
+  }
+}

packages/opentelemetry-metrics/src/export/controllers/index.ts

@@ -0,0 +1,18 @@
+/*!
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export * from './PushController';
+export * from './types';

packages/opentelemetry-metrics/src/export/controllers/types.ts

@@ -0,0 +1,22 @@
+/*!
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { MeterConfig } from '../../types';
+
+export interface PushControllerConfig extends MeterConfig {
+  /** Metric collect interval */
+  interval?: number;
+}

packages/opentelemetry-metrics/src/index.ts

@@ -16,9 +16,10 @@
 
 export * from './BoundInstrument';
 export * from './Meter';
-export * from './MeterProvider';
 export * from './Metric';
 export * from './MetricObservable';
 export * from './export/aggregators';
+export * from './export/controllers';
+export * from './export/Controller';
 export * from './export/ConsoleMetricExporter';
 export * from './export/types';

packages/opentelemetry-metrics/src/types.ts

@@ -64,9 +64,6 @@ export interface MeterConfig {
   /** Metric exporter. */
   exporter?: MetricExporter;
 
-  /** Metric collect interval */
-  interval?: number;
-
   /** Resource associated with metric telemetry */
   resource?: Resource;
 

packages/opentelemetry-metrics/test/Batcher.test.ts

@@ -17,7 +17,7 @@
 import * as assert from 'assert';
 import * as api from '@opentelemetry/api';
 import { NoopLogger } from '@opentelemetry/core';
-import { Meter, MeterProvider } from '../src';
+import { Meter, PushController } from '../src';
 
 describe('Batcher', () => {
   describe('Ungrouped', () => {
@@ -26,7 +26,7 @@ describe('Batcher', () => {
     let barCounter: api.BoundCounter;
     let counter: api.Metric<api.BoundCounter>;
     beforeEach(() => {
-      meter = new MeterProvider({
+      meter = new PushController({
         logger: new NoopLogger(),
         interval: 10000,
       }).getMeter('test-meter');

packages/opentelemetry-metrics/test/Meter.test.ts

@@ -21,7 +21,7 @@ import {
   CounterMetric,
   MetricKind,
   Sum,
-  MeterProvider,
+  PushController,
   MeasureMetric,
   Distribution,
   ObserverMetric,
@@ -48,7 +48,7 @@ describe('Meter', () => {
   const labels: api.Labels = { [keyb]: 'value2', [keya]: 'value1' };
 
   beforeEach(() => {
-    meter = new MeterProvider({
+    meter = new PushController({
       logger: new NoopLogger(),
     }).getMeter('test-meter');
   });
@@ -553,7 +553,7 @@ describe('Meter', () => {
   });
 
   it('should allow custom batcher', () => {
-    const customMeter = new MeterProvider().getMeter('custom-batcher', '*', {
+    const customMeter = new PushController().getMeter('custom-batcher', '*', {
       batcher: new CustomBatcher(),
     });
     assert.throws(() => {

packages/opentelemetry-metrics/test/export/ConsoleMetricExporter.test.ts

@@ -16,7 +16,7 @@
 
 import * as assert from 'assert';
 import * as sinon from 'sinon';
-import { ConsoleMetricExporter, MeterProvider, MetricKind } from '../../src';
+import { ConsoleMetricExporter, PushController, MetricKind } from '../../src';
 import { ValueType } from '@opentelemetry/api';
 
 describe('ConsoleMetricExporter', () => {
@@ -37,7 +37,7 @@ describe('ConsoleMetricExporter', () => {
     it('should export information about metrics', () => {
       const spyConsole = sinon.spy(console, 'log');
 
-      const meter = new MeterProvider().getMeter(
+      const meter = new PushController().getMeter(
         'test-console-metric-exporter'
       );
       const counter = meter.createCounter('counter', {