Gauge: Add support for constant labels (#468)

* Gauge: Add support for constant labels

* update CHANGELOG.md

* fix review comments

1. Remove map -> constantLabels
2. Make labels values and keys merging code consistent.
3. Update error message

* use  to test for both null and undefined

Author: mayurkale22

CHANGELOG.md

@@ -4,7 +4,7 @@ All notable changes to this project will be documented in this file.
 
 ## Unreleased
 
-
+- Gauge: Add support for constant labels.
 
 ## 0.0.10 - 2019-04-03
 - Add optional `compressedSize` and `uncompressedSize` params to `Span.addMessageEvent`

packages/opencensus-core/src/common/validations.ts

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+import {LabelKey, LabelValue} from '../metrics/export/types';
+
 /**
  * Validates that an object reference passed as a parameter to the calling
  * method is not null.
@@ -43,3 +45,24 @@ export function validateArrayElementsNotNull<T>(
     throw new Error(`${errorMessage} elements should not be a NULL`);
   }
 }
+
+/** Throws an error if any of the map elements is null. */
+export function validateMapElementNotNull<T>(
+    map: Map<T, T>, errorMessage: string) {
+  for (const [key, value] of map.entries()) {
+    if (key == null || value == null) {
+      throw new Error(`${errorMessage} elements should not be a NULL`);
+    }
+  }
+}
+
+/** Throws an error if any of the array element present in the map. */
+export function validateDuplicateKeys(
+    keys: LabelKey[], constantLabels: Map<LabelKey, LabelValue>) {
+  const keysAndConstantKeys =
+      new Set([...keys, ...constantLabels.keys()].map(k => k.key));
+  if (keysAndConstantKeys.size !== (keys.length + constantLabels.size)) {
+    throw new Error(
+        `The keys from LabelKeys should not be present in constantLabels or LabelKeys should not contains duplicate keys`);
+  }
+}

packages/opencensus-core/src/metrics/gauges/derived-gauge.ts

@@ -73,6 +73,7 @@ export class DerivedGauge implements types.Meter {
   private labelKeysLength: number;
   private registeredPoints: Map<string, GaugeEntry> = new Map();
   private extractor?: ValueExtractor;
+  private readonly constantLabelValues: LabelValue[];
 
   private static readonly LABEL_VALUE = 'labelValue';
   private static readonly LABEL_VALUES = 'labelValues';
@@ -94,12 +95,19 @@ export class DerivedGauge implements types.Meter {
    * @param {string} unit The unit of the metric.
    * @param {MetricDescriptorType} type The type of metric.
    * @param {LabelKey[]} labelKeys The list of the label keys.
+   * @param {Map<LabelKey, LabelValue>} constantLabels The map of constant
+   *     labels for the Metric.
    */
   constructor(
       name: string, description: string, unit: string,
-      type: MetricDescriptorType, labelKeys: LabelKey[]) {
-    this.metricDescriptor = {name, description, unit, type, labelKeys};
+      type: MetricDescriptorType, labelKeys: LabelKey[],
+      readonly constantLabels: Map<LabelKey, LabelValue>) {
     this.labelKeysLength = labelKeys.length;
+    const keysAndConstantKeys = [...labelKeys, ...constantLabels.keys()];
+    this.constantLabelValues = [...constantLabels.values()];
+
+    this.metricDescriptor =
+        {name, description, unit, type, labelKeys: keysAndConstantKeys};
   }
 
   // Checks if the specified collection is a LengthAttributeInterface.
@@ -211,7 +219,8 @@ export class DerivedGauge implements types.Meter {
       timeseries: Array.from(
           this.registeredPoints,
           ([_, gaugeEntry]) => ({
-            labelValues: gaugeEntry.labelValues,
+            labelValues:
+                [...gaugeEntry.labelValues, ...this.constantLabelValues],
             points: [{value: gaugeEntry.extractor(), timestamp}]
           } as TimeSeries))
     };

packages/opencensus-core/src/metrics/gauges/gauge.ts

@@ -28,6 +28,7 @@ export class Gauge implements types.Meter {
   private labelKeysLength: number;
   private defaultLabelValues: LabelValue[];
   private registeredPoints: Map<string, types.Point> = new Map();
+  private readonly constantLabelValues: LabelValue[];
 
   private static readonly LABEL_VALUE = 'labelValue';
   private static readonly LABEL_VALUES = 'labelValues';
@@ -42,12 +43,19 @@ export class Gauge implements types.Meter {
    * @param {string} unit The unit of the metric.
    * @param {MetricDescriptorType} type The type of metric.
    * @param {LabelKey[]} labelKeys The list of the label keys.
+   * @param {Map<LabelKey, LabelValue>} constantLabels The map of constant
+   *     labels for the Metric.
    */
   constructor(
       name: string, description: string, unit: string,
-      type: MetricDescriptorType, readonly labelKeys: LabelKey[]) {
-    this.metricDescriptor = {name, description, unit, type, labelKeys};
+      type: MetricDescriptorType, readonly labelKeys: LabelKey[],
+      readonly constantLabels: Map<LabelKey, LabelValue>) {
     this.labelKeysLength = labelKeys.length;
+    const keysAndConstantKeys = [...labelKeys, ...constantLabels.keys()];
+    this.constantLabelValues = [...constantLabels.values()];
+
+    this.metricDescriptor =
+        {name, description, unit, type, labelKeys: keysAndConstantKeys};
     this.defaultLabelValues = initializeDefaultLabels(this.labelKeysLength);
   }
 
@@ -116,7 +124,7 @@ export class Gauge implements types.Meter {
       throw new Error(Gauge.ERROR_MESSAGE_INVALID_SIZE);
     }
 
-    const point = new PointEntry(labelValues);
+    const point = new PointEntry([...labelValues, ...this.constantLabelValues]);
     this.registeredPoints.set(hash, point);
     return point;
   }

packages/opencensus-core/src/metrics/metric-registry.ts

@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-import {validateArrayElementsNotNull, validateNotNull} from '../common/validations';
-import {MeasureUnit,} from '../stats/types';
+import {validateArrayElementsNotNull, validateDuplicateKeys, validateMapElementNotNull, validateNotNull} from '../common/validations';
+import {MeasureUnit} from '../stats/types';
 import {BaseMetricProducer} from './export/base-metric-producer';
 import {Metric, MetricDescriptorType, MetricProducer} from './export/types';
 import {DerivedGauge} from './gauges/derived-gauge';
@@ -31,9 +31,11 @@ export class MetricRegistry {
 
   private static readonly NAME = 'name';
   private static readonly LABEL_KEY = 'labelKey';
+  private static readonly CONSTANT_LABELS = 'constantLabels';
   private static readonly DEFAULT_DESCRIPTION = '';
   private static readonly DEFAULT_UNIT = MeasureUnit.UNIT;
   private static readonly DEFAULT_LABEL_KEYS = [];
+  private static readonly DEFAULT_CONSTANT_LABEL = new Map();
 
   constructor() {
     this.metricProducer = new MetricProducerForRegistry(this.registeredMetrics);
@@ -54,13 +56,18 @@ export class MetricRegistry {
     const unit = (options && options.unit) || MetricRegistry.DEFAULT_UNIT;
     const labelKeys =
         (options && options.labelKeys) || MetricRegistry.DEFAULT_LABEL_KEYS;
-    // TODO (mayurkale): Add support for constantLabels
+    const constantLabels = (options && options.constantLabels) ||
+        MetricRegistry.DEFAULT_CONSTANT_LABEL;
+    // TODO(mayurkale): Add support for resource
 
     validateArrayElementsNotNull(labelKeys, MetricRegistry.LABEL_KEY);
+    validateMapElementNotNull(constantLabels, MetricRegistry.CONSTANT_LABELS);
+    validateDuplicateKeys(labelKeys, constantLabels);
+
     const labelKeysCopy = Object.assign([], labelKeys);
     const int64Gauge = new Gauge(
         validateNotNull(name, MetricRegistry.NAME), description, unit,
-        MetricDescriptorType.GAUGE_INT64, labelKeysCopy);
+        MetricDescriptorType.GAUGE_INT64, labelKeysCopy, constantLabels);
     this.registerMetric(name, int64Gauge);
     return int64Gauge;
   }
@@ -80,13 +87,18 @@ export class MetricRegistry {
     const unit = (options && options.unit) || MetricRegistry.DEFAULT_UNIT;
     const labelKeys =
         (options && options.labelKeys) || MetricRegistry.DEFAULT_LABEL_KEYS;
-    // TODO (mayurkale): Add support for constantLabels
+    const constantLabels = (options && options.constantLabels) ||
+        MetricRegistry.DEFAULT_CONSTANT_LABEL;
+    // TODO(mayurkale): Add support for resource
 
     validateArrayElementsNotNull(labelKeys, MetricRegistry.LABEL_KEY);
+    validateMapElementNotNull(constantLabels, MetricRegistry.CONSTANT_LABELS);
+    validateDuplicateKeys(labelKeys, constantLabels);
+
     const labelKeysCopy = Object.assign([], labelKeys);
     const doubleGauge = new Gauge(
         validateNotNull(name, MetricRegistry.NAME), description, unit,
-        MetricDescriptorType.GAUGE_DOUBLE, labelKeysCopy);
+        MetricDescriptorType.GAUGE_DOUBLE, labelKeysCopy, constantLabels);
     this.registerMetric(name, doubleGauge);
     return doubleGauge;
   }
@@ -106,13 +118,18 @@ export class MetricRegistry {
     const unit = (options && options.unit) || MetricRegistry.DEFAULT_UNIT;
     const labelKeys =
         (options && options.labelKeys) || MetricRegistry.DEFAULT_LABEL_KEYS;
-    // TODO (mayurkale): Add support for constantLabels
+    const constantLabels = (options && options.constantLabels) ||
+        MetricRegistry.DEFAULT_CONSTANT_LABEL;
+    // TODO(mayurkale): Add support for resource
 
     validateArrayElementsNotNull(labelKeys, MetricRegistry.LABEL_KEY);
+    validateMapElementNotNull(constantLabels, MetricRegistry.CONSTANT_LABELS);
+    validateDuplicateKeys(labelKeys, constantLabels);
+
     const labelKeysCopy = Object.assign([], labelKeys);
     const derivedInt64Gauge = new DerivedGauge(
         validateNotNull(name, MetricRegistry.NAME), description, unit,
-        MetricDescriptorType.GAUGE_INT64, labelKeysCopy);
+        MetricDescriptorType.GAUGE_INT64, labelKeysCopy, constantLabels);
     this.registerMetric(name, derivedInt64Gauge);
     return derivedInt64Gauge;
   }
@@ -132,13 +149,18 @@ export class MetricRegistry {
     const unit = (options && options.unit) || MetricRegistry.DEFAULT_UNIT;
     const labelKeys =
         (options && options.labelKeys) || MetricRegistry.DEFAULT_LABEL_KEYS;
-    // TODO (mayurkale): Add support for constantLabels
+    const constantLabels = (options && options.constantLabels) ||
+        MetricRegistry.DEFAULT_CONSTANT_LABEL;
+    // TODO(mayurkale): Add support for resource
 
     validateArrayElementsNotNull(labelKeys, MetricRegistry.LABEL_KEY);
+    validateMapElementNotNull(constantLabels, MetricRegistry.CONSTANT_LABELS);
+    validateDuplicateKeys(labelKeys, constantLabels);
+
     const labelKeysCopy = Object.assign([], labelKeys);
     const derivedDoubleGauge = new DerivedGauge(
         validateNotNull(name, MetricRegistry.NAME), description, unit,
-        MetricDescriptorType.GAUGE_DOUBLE, labelKeysCopy);
+        MetricDescriptorType.GAUGE_DOUBLE, labelKeysCopy, constantLabels);
     this.registerMetric(name, derivedDoubleGauge);
     return derivedDoubleGauge;
   }

packages/opencensus-core/test/test-derived-gauge.ts

@@ -15,7 +15,6 @@
  */
 
 import * as assert from 'assert';
-
 import {TEST_ONLY} from '../src/common/time-util';
 import {LabelKey, LabelValue, MetricDescriptorType, Timestamp} from '../src/metrics/export/types';
 import {DerivedGauge} from '../src/metrics/gauges/derived-gauge';
@@ -29,6 +28,9 @@ const LABEL_KEYS: LabelKey[] = [{key: 'code', description: 'desc'}];
 const LABEL_VALUES_200: LabelValue[] = [{value: '200'}];
 const LABEL_VALUES_400: LabelValue[] = [{value: '400'}];
 const LABEL_VALUES_EXRTA: LabelValue[] = [{value: '200'}, {value: '400'}];
+const EMPTY_CONSTANT_LABELS = new Map();
+const CONSTANT_LABELS = new Map();
+CONSTANT_LABELS.set({key: 'host', description: 'host'}, {value: 'localhost'});
 
 describe('DerivedGauge', () => {
   let instance: DerivedGauge;
@@ -45,7 +47,8 @@ describe('DerivedGauge', () => {
 
   beforeEach(() => {
     instance = new DerivedGauge(
-        METRIC_NAME, METRIC_DESCRIPTION, UNIT, GAUGE_INT64, LABEL_KEYS);
+        METRIC_NAME, METRIC_DESCRIPTION, UNIT, GAUGE_INT64, LABEL_KEYS,
+        EMPTY_CONSTANT_LABELS);
 
     process.hrtime = () => [100, 1e7];
     Date.now = () => 1450000000000;
@@ -148,7 +151,8 @@ describe('DerivedGauge', () => {
       }
       const obj = new QueueManager();
       const doubleInstance = new DerivedGauge(
-          METRIC_NAME, METRIC_DESCRIPTION, UNIT, GAUGE_DOUBLE, LABEL_KEYS);
+          METRIC_NAME, METRIC_DESCRIPTION, UNIT, GAUGE_DOUBLE, LABEL_KEYS,
+          EMPTY_CONSTANT_LABELS);
       doubleInstance.createTimeSeries(LABEL_VALUES_200, obj);
       const metric = doubleInstance.getMetric();
       assert.notEqual(metric, null);
@@ -171,6 +175,39 @@ describe('DerivedGauge', () => {
           }]);
     });
 
+    it('should return a Metric (Double) - custom object', () => {
+      class QueueManager {
+        getValue(): number {
+          return 0.7;
+        }
+      }
+      const obj = new QueueManager();
+      const doubleInstance = new DerivedGauge(
+          METRIC_NAME, METRIC_DESCRIPTION, UNIT, GAUGE_DOUBLE, LABEL_KEYS,
+          CONSTANT_LABELS);
+      doubleInstance.createTimeSeries(LABEL_VALUES_200, obj);
+      const metric = doubleInstance.getMetric();
+      assert.notEqual(metric, null);
+      assert.deepStrictEqual(metric!.descriptor, {
+        name: METRIC_NAME,
+        description: METRIC_DESCRIPTION,
+        unit: UNIT,
+        type: GAUGE_DOUBLE,
+        labelKeys: [...LABEL_KEYS, ...Array.from(CONSTANT_LABELS.keys())]
+      });
+      assert.equal(metric!.timeseries.length, 1);
+      assert.deepStrictEqual(
+          metric!.timeseries, [{
+            labelValues:
+                [...LABEL_VALUES_200, ...Array.from(CONSTANT_LABELS.values())],
+            points: [{
+              value: 0.7,
+              timestamp:
+                  {nanos: mockedTime.nanos, seconds: mockedTime.seconds}
+            }]
+          }]);
+    });
+
     it('should not create same timeseries again', () => {
       const map = new Map();
       instance.createTimeSeries(LABEL_VALUES_200, map);