Add support for unregister stats exporter whenever the exporter is not needed anymore (#397)

Author: mayurkale22

CHANGELOG.md

@@ -16,6 +16,7 @@ All notable changes to this project will be documented in this file.
 - Enforce `--strictNullChecks` and `--noUnusedLocals` Compiler Options on [opencensus-instrumentation-http], [opencensus-instrumentation-grpc] and [opencensus-propagation-tracecontext] packages.
 - Enforce `--strictNullChecks` and `--noUnusedLocals` Compiler Options on  [opencensus-exporter-zipkin] packages.
 - Add NoRecordRootSpan, NoRecordSpan and NoRecordSpanBase.
+- Add an API `globalStats.unregisterExporter()`.
 
 ## 0.0.9 - 2019-02-12
 - Add Metrics API.

packages/opencensus-core/src/exporters/console-exporter.ts

@@ -106,4 +106,7 @@ export class ConsoleStatsExporter implements types.StatsEventListener {
   start(): void {
     // TODO(mayurkale): dependency with PR#253.
   }
+
+  /** Stops the exporter. */
+  stop(): void {}
 }

packages/opencensus-core/src/exporters/types.ts

@@ -54,6 +54,9 @@ export interface StatsEventListener {
    * batched data to backend.
    */
   start(): void;
+
+  /** Stops the exporter. */
+  stop(): void;
 }
 
 export type ExporterConfig = configTypes.BufferConfig;

packages/opencensus-core/src/stats/stats.ts

@@ -107,6 +107,19 @@ export class BaseStats implements Stats {
     exporter.start();
   }
 
+  /**
+   * Unregisters an exporter. It should be called whenever the exporter is not
+   * needed anymore.
+   * @param exporter An stats exporter
+   */
+  unregisterExporter(exporter: StatsEventListener): void {
+    if (exporter) {
+      this.statsEventListeners = this.statsEventListeners.filter(
+          currentExporter => currentExporter !== exporter);
+      exporter.stop();
+    }
+  }
+
   /**
    * Creates a measure of type Double.
    * @param name The measure name

packages/opencensus-core/src/stats/types.ts

@@ -86,6 +86,13 @@ export interface Stats {
    * @param exporter An stats exporter
    */
   registerExporter(exporter: StatsEventListener): void;
+
+  /**
+   * Unregisters an exporter. It should be called whenever the exporter is not
+   * needed anymore.
+   * @param exporter An stats exporter
+   */
+  unregisterExporter(exporter: StatsEventListener): void;
 }
 
 /**

packages/opencensus-core/test/test-stats.ts

@@ -35,6 +35,8 @@ class TestExporter implements StatsEventListener {
     // TODO(mayurkale): dependency with PR#253.
   }
 
+  stop(): void {}
+
   clean() {
     this.registeredViews = [];
     this.recordedMeasurements = [];
@@ -143,6 +145,21 @@ describe('Stats', () => {
     });
   });
 
+  describe('unregisterExporter()', () => {
+    const testExporter = new TestExporter();
+
+    it('should unregister the exporter', () => {
+      globalStats.registerExporter(testExporter);
+      const measure = globalStats.createMeasureInt64(measureName, measureUnit);
+      const view = new BaseView(
+          viewName, measure, AggregationType.LAST_VALUE, tagKeys, description);
+      globalStats.unregisterExporter(testExporter);
+      globalStats.registerView(view);
+
+      assert.strictEqual(testExporter.registeredViews.length, 0);
+    });
+  });
+
   describe('record()', () => {
     let measure: Measure;
     const testExporter = new TestExporter();

packages/opencensus-exporter-prometheus/src/prometheus-stats.ts

@@ -95,6 +95,11 @@ export class PrometheusStatsExporter implements StatsEventListener {
     // // it to backend (dependency with PR#253).
   }
 
+  /** Stops the exporter. */
+  stop(): void {
+    this.stopServer();
+  }
+
   private getLabelValues(columns: TagKey[], tags: Map<TagKey, TagValue>):
       labelValues {
     const labels: labelValues = {};

packages/opencensus-exporter-stackdriver/src/stackdriver-monitoring.ts

@@ -199,7 +199,7 @@ export class StackdriverStatsExporter implements StatsEventListener {
    * Clear the interval timer to stop uploading metrics. It should be called
    * whenever the exporter is not needed anymore.
    */
-  close() {
+  stop() {
     clearInterval(this.timer);
   }
 

packages/opencensus-exporter-stackdriver/test/test-stackdriver-monitoring.ts

@@ -71,7 +71,7 @@ describe('Stackdriver Stats Exporter', () => {
     });
 
     afterEach(() => {
-      exporter.close();
+      exporter.stop();
       mockLogger.cleanAll();
       globalStats.clear();
     });

packages/opencensus-exporter-zpages/src/zpages.ts

@@ -134,6 +134,9 @@ export class ZpagesExporter implements Exporter, StatsEventListener {
     // TODO(mayurkale): dependency with PR#253.
   }
 
+  /** Stops the exporter. */
+  stop(): void {}
+
   /**
    * Send a trace to traces array
    * @param trace the rootSpan to be sent to the array list