Exporter/Prometheus: Enforce strictNullChecks and noUnusedLocals

examples/stats/exporter/prometheus.js

@@ -117,13 +117,11 @@ lineReader.on('line', function (line) {
 
     globalStats.record([{
       measure: mLineLengths,
-      tags,
       value: processedLine.length
     }], tags);
 
     globalStats.record([{
       measure: mLatencyMs,
-      tags,
       value: sinceInMilliseconds(endNanoseconds, startNanoseconds)
     }], tags);
   } catch (err) {

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

@@ -197,7 +197,7 @@ export interface View {
    * Returns a snapshot of an AggregationData for that tags/labels values.
    * @param tagValues The desired data's tag values.
    */
-  getSnapshot(tagValues: TagValue[]): AggregationData;
+  getSnapshot(tagValues: Array<TagValue|null>): AggregationData;
   /** Gets the view's tag keys */
   getColumns(): TagKey[];
   /** Gets view`s metric */

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

@@ -257,7 +257,7 @@ export class BaseView implements View {
    * @param tags The desired data's tags
    * @returns {AggregationData}
    */
-  getSnapshot(tagValues: TagValue[]): AggregationData {
+  getSnapshot(tagValues: Array<TagValue|null>): AggregationData {
     return this.tagValueAggregationMap[this.encodeTagValues(tagValues)];
   }
 

packages/opencensus-exporter-prometheus/README.md

@@ -1,7 +1,9 @@
-# OpenCensus Prometheus Exporter for Node.js
+# OpenCensus Prometheus Stats Exporter
 [![Gitter chat][gitter-image]][gitter-url] ![Node Version][node-img] [![NPM Published Version][npm-img]][npm-url] ![dependencies Status][dependencies-status] ![devDependencies Status][devdependencies-status] ![Apache License][license-image]
 
-The OpenCensus Prometheus Exporter allows the user to send collected stats with [OpenCensus Core](https://github.com/census-instrumentation/opencensus-core) to Prometheus.
+The OpenCensus Prometheus Stats Exporter allows the user to send collected stats with [OpenCensus Core](https://github.com/census-instrumentation/opencensus-core) to Prometheus.
+
+[Prometheus](https://prometheus.io/) is a monitoring system that collects metrics, by scraping exposed endpoints at regular intervals, evaluating rule expressions. It can also trigger alerts if certain conditions are met. For assistance setting up Prometheus, [Click here](https://opencensus.io/codelabs/prometheus/#0) for a guided codelab.
 
 This package is still at an early stage of development, and is subject to change.
 

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

@@ -47,7 +47,7 @@ export class PrometheusStatsExporter implements StatsEventListener {
   private prefix: string;
   private port: number;
   private app = express();
-  private server: http.Server;
+  private server?: http.Server;
   // Registry instance from Prometheus to keep the metrics
   private registry = new Registry();
 
@@ -105,7 +105,10 @@ export class PrometheusStatsExporter implements StatsEventListener {
     const labels: labelValues = {};
     columns.forEach((tagKey) => {
       if (tags.has(tagKey)) {
-        labels[tagKey.name] = tags.get(tagKey).value;
+        const tagValue = tags.get(tagKey);
+        if (tagValue) {
+          labels[tagKey.name] = tagValue.value;
+        }
       }
     });
     return labels;
@@ -149,8 +152,7 @@ export class PrometheusStatsExporter implements StatsEventListener {
         metric = new Histogram(distribution);
         break;
       default:
-        this.logger.error('Aggregation %s is not supported', view.aggregation);
-        return null;
+        this.logger.error(`Aggregation ${view.aggregation} is not supported`);
     }
 
     this.registry.registerMetric(metric);

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

@@ -17,7 +17,6 @@
 import {AggregationType, globalStats, Measure, MeasureUnit, TagMap} from '@opencensus/core';
 import * as assert from 'assert';
 import * as http from 'http';
-
 import {PrometheusStatsExporter} from '../src/';
 
 describe('Prometheus Stats Exporter', () => {
@@ -48,7 +47,7 @@ describe('Prometheus Stats Exporter', () => {
   it('should create a count aggregation', (done) => {
     const view = globalStats.createView(
         'ocnodemetrics/countview', measure, AggregationType.COUNT, tagKeys,
-        'A count aggregation example', null);
+        'A count aggregation example');
     const measurement = {measure, value: 2};
     const measurement2 = {measure, value: 3};
     globalStats.registerView(view);
@@ -75,7 +74,7 @@ describe('Prometheus Stats Exporter', () => {
         globalStats.createMeasureDouble('testMeasureDouble', MeasureUnit.UNIT);
     const view = globalStats.createView(
         'ocnodemetrics/sumview', measure, AggregationType.SUM, tagKeys,
-        'A sum aggregation example', null);
+        'A sum aggregation example');
     const measurement = {measure, value: 2};
     const measurement2 = {measure, value: 3};
     globalStats.registerView(view);
@@ -102,7 +101,7 @@ describe('Prometheus Stats Exporter', () => {
         globalStats.createMeasureDouble('testMeasureDouble', MeasureUnit.UNIT);
     const view = globalStats.createView(
         'ocnodemetrics/sumview1', measure, AggregationType.SUM, tagKeys,
-        'A sum aggregation example', null);
+        'A sum aggregation example');
     const measurement = {measure, value: 2};
     const measurement2 = {measure, value: 3};
     globalStats.registerView(view);
@@ -128,7 +127,7 @@ describe('Prometheus Stats Exporter', () => {
         globalStats.createMeasureDouble('testMeasureDouble', MeasureUnit.UNIT);
     const view = globalStats.createView(
         'ocnodemetrics/lastvalueview', measure, AggregationType.LAST_VALUE,
-        tagKeys, 'A last value aggregation example', null);
+        tagKeys, 'A last value aggregation example');
     const measurement = {measure, value: 2};
     const measurement2 = {measure, value: 3};
     globalStats.registerView(view);
@@ -247,7 +246,7 @@ describe('Prometheus Stats Exporter with prefix option', () => {
   it('should create a count aggregation with le labels', (done) => {
     const view = globalStats.createView(
         'test/key-1', measure, AggregationType.COUNT, tagKeys,
-        'A count aggregation example', null);
+        'A count aggregation example');
     const measurement = {measure, value: 2};
     const measurement2 = {measure, value: 3};
     globalStats.registerView(view);

packages/opencensus-exporter-prometheus/tsconfig.json

@@ -6,7 +6,8 @@
     "pretty": true,
     "module": "commonjs",
     "target": "es6",
-    "strictNullChecks": false
+    "strictNullChecks": true,
+    "noUnusedLocals": true
   },
   "exclude": [
     "node_modules"