From 3cf95a04c676976cd7bb2a97b9669747d62e8c4b Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Mon, 28 Oct 2019 14:25:59 -0700
Subject: [PATCH 01/13] feat: implement labelset

---
 .../src/metrics/NoopMeter.ts                  |  9 ++--
 .../test/metrics/NoopMeter.test.ts            | 13 +++---
 packages/opentelemetry-metrics/src/Handle.ts  |  8 ++--
 packages/opentelemetry-metrics/src/Metric.ts  | 24 +++++-----
 .../opentelemetry-metrics/src/export/types.ts |  6 +--
 packages/opentelemetry-metrics/src/types.ts   |  4 --
 .../opentelemetry-metrics/test/Meter.test.ts  | 46 +++++++++----------
 .../opentelemetry-types/src/metrics/Metric.ts | 13 +++---
 8 files changed, 60 insertions(+), 63 deletions(-)

diff --git a/packages/opentelemetry-core/src/metrics/NoopMeter.ts b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
index ccff9f1358..5cd17e93dd 100644
--- a/packages/opentelemetry-core/src/metrics/NoopMeter.ts
+++ b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
@@ -23,6 +23,7 @@ import {
   MetricOptions,
   MeasureHandle,
   SpanContext,
+  LabelSet
 } from '@opentelemetry/types';
 
 /**
@@ -70,9 +71,9 @@ export class NoopMetric<T> implements Metric<T> {
    * Returns a Handle associated with specified label values.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for every operations.
-   * @param labelValues the list of label values.
+   * @param labels the object of label set.
    */
-  getHandle(labelValues: string[]): T {
+  getHandle(labels: LabelSet): T {
     return this._handle;
   }
 
@@ -85,9 +86,9 @@ export class NoopMetric<T> implements Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labelValues the list of label values.
+   * @param labels the object of label set.
    */
-  removeHandle(labelValues: string[]): void {
+  removeHandle(labels: LabelSet): void {
     return;
   }
 
diff --git a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
index b37762bc7c..4999027e54 100644
--- a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
+++ b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
@@ -24,23 +24,25 @@ import {
   NOOP_MEASURE_HANDLE,
   NOOP_MEASURE_METRIC,
 } from '../../src/metrics/NoopMeter';
+import { LabelSet } from '@opentelemetry/types';
 
 describe('NoopMeter', () => {
   it('should not crash', () => {
     const meter = new NoopMeter();
     const counter = meter.createCounter('some-name');
+    const labels: LabelSet = { 'key1': 'val1', 'key2': 'val2'};
     // ensure NoopMetric does not crash.
     counter.setCallback(() => {
       assert.fail('callback occurred');
     });
-    counter.getHandle(['val1', 'val2']).add(1);
+    counter.getHandle(labels).add(1);
     counter.getDefaultHandle().add(1);
-    counter.removeHandle(['val1', 'val2']);
+    counter.removeHandle(labels);
 
     // ensure the correct noop const is returned
     assert.strictEqual(counter, NOOP_COUNTER_METRIC);
     assert.strictEqual(
-      counter.getHandle(['val1', 'val2']),
+      counter.getHandle(labels),
       NOOP_COUNTER_HANDLE
     );
     assert.strictEqual(counter.getDefaultHandle(), NOOP_COUNTER_HANDLE);
@@ -62,7 +64,7 @@ describe('NoopMeter', () => {
     assert.strictEqual(measure, NOOP_MEASURE_METRIC);
     assert.strictEqual(measure.getDefaultHandle(), NOOP_MEASURE_HANDLE);
     assert.strictEqual(
-      measure.getHandle(['val1', 'val2']),
+      measure.getHandle(labels),
       NOOP_MEASURE_HANDLE
     );
 
@@ -72,12 +74,11 @@ describe('NoopMeter', () => {
     // ensure the correct noop const is returned
     assert.strictEqual(gauge, NOOP_GAUGE_METRIC);
     assert.strictEqual(gauge.getDefaultHandle(), NOOP_GAUGE_HANDLE);
-    assert.strictEqual(gauge.getHandle(['val1', 'val2']), NOOP_GAUGE_HANDLE);
+    assert.strictEqual(gauge.getHandle(labels), NOOP_GAUGE_HANDLE);
 
     const options = {
       component: 'tests',
       description: 'the testing package',
-      labelKeys: ['key1', 'key2'],
     };
 
     const measureWithOptions = meter.createMeasure('some-name', options);
diff --git a/packages/opentelemetry-metrics/src/Handle.ts b/packages/opentelemetry-metrics/src/Handle.ts
index 45bb34e390..85ef3b1e98 100644
--- a/packages/opentelemetry-metrics/src/Handle.ts
+++ b/packages/opentelemetry-metrics/src/Handle.ts
@@ -28,7 +28,7 @@ export class CounterHandle implements types.CounterHandle {
   constructor(
     private readonly _disabled: boolean,
     private readonly _monotonic: boolean,
-    private readonly _labelValues: string[],
+    private readonly _labels: types.LabelSet,
     private readonly _logger: types.Logger
   ) {}
 
@@ -50,7 +50,7 @@ export class CounterHandle implements types.CounterHandle {
    */
   getTimeSeries(timestamp: types.HrTime): TimeSeries {
     return {
-      labelValues: this._labelValues.map(value => ({ value })),
+      labelValues: Object.values(this._labels).map(value => ({ value })),
       points: [{ value: this._data, timestamp }],
     };
   }
@@ -66,7 +66,7 @@ export class GaugeHandle implements types.GaugeHandle {
   constructor(
     private readonly _disabled: boolean,
     private readonly _monotonic: boolean,
-    private readonly _labelValues: string[],
+    private readonly _labels: types.LabelSet,
     private readonly _logger: types.Logger
   ) {}
 
@@ -88,7 +88,7 @@ export class GaugeHandle implements types.GaugeHandle {
    */
   getTimeSeries(timestamp: types.HrTime): TimeSeries {
     return {
-      labelValues: this._labelValues.map(value => ({ value })),
+      labelValues: Object.values(this._labels).map(value => ({ value })),
       points: [{ value: this._data, timestamp }],
     };
   }
diff --git a/packages/opentelemetry-metrics/src/Metric.ts b/packages/opentelemetry-metrics/src/Metric.ts
index 1daecfd88c..9befe98cb7 100644
--- a/packages/opentelemetry-metrics/src/Metric.ts
+++ b/packages/opentelemetry-metrics/src/Metric.ts
@@ -36,13 +36,13 @@ export abstract class Metric<T> implements types.Metric<T> {
    * Returns a Handle associated with specified label values.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for each operation.
-   * @param labelValues the list of label values.
+   * @param labels the object of label set.
    */
-  getHandle(labelValues: string[]): T {
-    const hash = hashLabelValues(labelValues);
+  getHandle(labels: types.LabelSet): T {
+    const hash = hashLabelValues(Object.values(labels));
     if (this._handles.has(hash)) return this._handles.get(hash)!;
 
-    const handle = this._makeHandle(labelValues);
+    const handle = this._makeHandle(labels);
     this._handles.set(hash, handle);
     return handle;
   }
@@ -58,10 +58,10 @@ export abstract class Metric<T> implements types.Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labelValues the list of label values.
+   * @param labels the object of label set.
    */
-  removeHandle(labelValues: string[]): void {
-    this._handles.delete(hashLabelValues(labelValues));
+  removeHandle(labels: types.LabelSet): void {
+    this._handles.delete(hashLabelValues(Object.values(labels)));
   }
 
   /**
@@ -77,7 +77,7 @@ export abstract class Metric<T> implements types.Metric<T> {
     return;
   }
 
-  protected abstract _makeHandle(labelValues: string[]): T;
+  protected abstract _makeHandle(labels: types.LabelSet): T;
 }
 
 /** This is a SDK implementation of Counter Metric. */
@@ -85,11 +85,11 @@ export class CounterMetric extends Metric<CounterHandle> {
   constructor(name: string, options: MetricOptions) {
     super(name, options);
   }
-  protected _makeHandle(labelValues: string[]): CounterHandle {
+  protected _makeHandle(labels: types.LabelSet): CounterHandle {
     return new CounterHandle(
       this._disabled,
       this._monotonic,
-      labelValues,
+      labels,
       this._logger
     );
   }
@@ -100,11 +100,11 @@ export class GaugeMetric extends Metric<GaugeHandle> {
   constructor(name: string, options: MetricOptions) {
     super(name, options);
   }
-  protected _makeHandle(labelValues: string[]): GaugeHandle {
+  protected _makeHandle(labels: types.LabelSet): GaugeHandle {
     return new GaugeHandle(
       this._disabled,
       this._monotonic,
-      labelValues,
+      labels,
       this._logger
     );
   }
diff --git a/packages/opentelemetry-metrics/src/export/types.ts b/packages/opentelemetry-metrics/src/export/types.ts
index 582d3b85a4..12d31a7c0f 100644
--- a/packages/opentelemetry-metrics/src/export/types.ts
+++ b/packages/opentelemetry-metrics/src/export/types.ts
@@ -22,7 +22,7 @@
  * opentelemetry-proto/opentelemetry/proto/metrics/v1/metrics.proto
  */
 
-import { HrTime } from '@opentelemetry/types';
+import { HrTime, LabelSet } from '@opentelemetry/types';
 import { Resource, ExportResult } from '@opentelemetry/base';
 
 export interface ReadableMetric {
@@ -61,8 +61,8 @@ export interface MetricDescriptor {
   readonly unit: string;
   /** MetricDescriptor type */
   readonly type: MetricDescriptorType;
-  /** The label keys associated with the metric descriptor. */
-  readonly labelKeys: string[];
+  /** The label set associated with the metric descriptor. */
+  readonly labels: LabelSet;
 }
 
 /**
diff --git a/packages/opentelemetry-metrics/src/types.ts b/packages/opentelemetry-metrics/src/types.ts
index d4078bbfcf..b1e262bd5f 100644
--- a/packages/opentelemetry-metrics/src/types.ts
+++ b/packages/opentelemetry-metrics/src/types.ts
@@ -28,9 +28,6 @@ export interface MetricOptions {
   /** The unit of the Metric values. */
   unit: string;
 
-  /** The list of label keys for the Metric. */
-  labelKeys: string[];
-
   /** The map of constant labels for the Metric. */
   constantLabels?: Map<string, string>;
 
@@ -63,5 +60,4 @@ export const DEFAULT_METRIC_OPTIONS = {
   disabled: false,
   description: '',
   unit: '1',
-  labelKeys: [],
 };
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index 5567cc2338..4a0e80f7b3 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -21,7 +21,7 @@ import { NoopLogger } from '@opentelemetry/core';
 
 describe('Meter', () => {
   let meter: Meter;
-  const labelValues = ['value'];
+  const labels: types.LabelSet = {'key': 'value'};
   const hrTime: types.HrTime = [22, 400000000];
 
   beforeEach(() => {
@@ -49,7 +49,7 @@ describe('Meter', () => {
     describe('.getHandle()', () => {
       it('should create a counter handle', () => {
         const counter = meter.createCounter('name');
-        const handle = counter.getHandle(labelValues);
+        const handle = counter.getHandle(labels);
         handle.add(10);
         assert.strictEqual(handle['_data'], 10);
         handle.add(10);
@@ -58,7 +58,7 @@ describe('Meter', () => {
 
       it('should return the timeseries', () => {
         const counter = meter.createCounter('name');
-        const handle = counter.getHandle(['value1', 'value2']);
+        const handle = counter.getHandle({'key1': 'value1', 'key2': 'value2'});
         handle.add(20);
         assert.deepStrictEqual(handle.getTimeSeries(hrTime), {
           labelValues: [{ value: 'value1' }, { value: 'value2' }],
@@ -68,7 +68,7 @@ describe('Meter', () => {
 
       it('should add positive values by default', () => {
         const counter = meter.createCounter('name');
-        const handle = counter.getHandle(labelValues);
+        const handle = counter.getHandle(labels);
         handle.add(10);
         assert.strictEqual(handle['_data'], 10);
         handle.add(-100);
@@ -79,7 +79,7 @@ describe('Meter', () => {
         const counter = meter.createCounter('name', {
           disabled: true,
         });
-        const handle = counter.getHandle(labelValues);
+        const handle = counter.getHandle(labels);
         handle.add(10);
         assert.strictEqual(handle['_data'], 0);
       });
@@ -88,16 +88,16 @@ describe('Meter', () => {
         const counter = meter.createCounter('name', {
           monotonic: false,
         });
-        const handle = counter.getHandle(labelValues);
+        const handle = counter.getHandle(labels);
         handle.add(-10);
         assert.strictEqual(handle['_data'], -10);
       });
 
       it('should return same handle on same label values', () => {
         const counter = meter.createCounter('name');
-        const handle = counter.getHandle(labelValues);
+        const handle = counter.getHandle(labels);
         handle.add(10);
-        const handle1 = counter.getHandle(labelValues);
+        const handle1 = counter.getHandle(labels);
         handle1.add(10);
         assert.strictEqual(handle['_data'], 20);
         assert.strictEqual(handle, handle1);
@@ -107,11 +107,11 @@ describe('Meter', () => {
     describe('.removeHandle()', () => {
       it('should remove a counter handle', () => {
         const counter = meter.createCounter('name');
-        const handle = counter.getHandle(labelValues);
+        const handle = counter.getHandle(labels);
         assert.strictEqual(counter['_handles'].size, 1);
-        counter.removeHandle(labelValues);
+        counter.removeHandle(labels);
         assert.strictEqual(counter['_handles'].size, 0);
-        const handle1 = counter.getHandle(labelValues);
+        const handle1 = counter.getHandle(labels);
         assert.strictEqual(counter['_handles'].size, 1);
         assert.notStrictEqual(handle, handle1);
       });
@@ -123,7 +123,7 @@ describe('Meter', () => {
 
       it('should clear all handles', () => {
         const counter = meter.createCounter('name');
-        counter.getHandle(labelValues);
+        counter.getHandle(labels);
         assert.strictEqual(counter['_handles'].size, 1);
         counter.clear();
         assert.strictEqual(counter['_handles'].size, 0);
@@ -150,7 +150,7 @@ describe('Meter', () => {
     describe('.getHandle()', () => {
       it('should create a gauge handle', () => {
         const gauge = meter.createGauge('name');
-        const handle = gauge.getHandle(labelValues);
+        const handle = gauge.getHandle(labels);
         handle.set(10);
         assert.strictEqual(handle['_data'], 10);
         handle.set(250);
@@ -159,7 +159,7 @@ describe('Meter', () => {
 
       it('should return the timeseries', () => {
         const gauge = meter.createGauge('name');
-        const handle = gauge.getHandle(['v1', 'v2']);
+        const handle = gauge.getHandle({'k1': 'v1', 'k2': 'v2'});
         handle.set(150);
         assert.deepStrictEqual(handle.getTimeSeries(hrTime), {
           labelValues: [{ value: 'v1' }, { value: 'v2' }],
@@ -169,7 +169,7 @@ describe('Meter', () => {
 
       it('should go up and down by default', () => {
         const gauge = meter.createGauge('name');
-        const handle = gauge.getHandle(labelValues);
+        const handle = gauge.getHandle(labels);
         handle.set(10);
         assert.strictEqual(handle['_data'], 10);
         handle.set(-100);
@@ -180,7 +180,7 @@ describe('Meter', () => {
         const gauge = meter.createGauge('name', {
           disabled: true,
         });
-        const handle = gauge.getHandle(labelValues);
+        const handle = gauge.getHandle(labels);
         handle.set(10);
         assert.strictEqual(handle['_data'], 0);
       });
@@ -189,16 +189,16 @@ describe('Meter', () => {
         const gauge = meter.createGauge('name', {
           monotonic: true,
         });
-        const handle = gauge.getHandle(labelValues);
+        const handle = gauge.getHandle(labels);
         handle.set(-10);
         assert.strictEqual(handle['_data'], 0);
       });
 
       it('should return same handle on same label values', () => {
         const gauge = meter.createGauge('name');
-        const handle = gauge.getHandle(labelValues);
+        const handle = gauge.getHandle(labels);
         handle.set(10);
-        const handle1 = gauge.getHandle(labelValues);
+        const handle1 = gauge.getHandle(labels);
         handle1.set(10);
         assert.strictEqual(handle['_data'], 10);
         assert.strictEqual(handle, handle1);
@@ -208,11 +208,11 @@ describe('Meter', () => {
     describe('.removeHandle()', () => {
       it('should remove the gauge handle', () => {
         const gauge = meter.createGauge('name');
-        const handle = gauge.getHandle(labelValues);
+        const handle = gauge.getHandle(labels);
         assert.strictEqual(gauge['_handles'].size, 1);
-        gauge.removeHandle(labelValues);
+        gauge.removeHandle(labels);
         assert.strictEqual(gauge['_handles'].size, 0);
-        const handle1 = gauge.getHandle(labelValues);
+        const handle1 = gauge.getHandle(labels);
         assert.strictEqual(gauge['_handles'].size, 1);
         assert.notStrictEqual(handle, handle1);
       });
@@ -224,7 +224,7 @@ describe('Meter', () => {
 
       it('should clear all handles', () => {
         const gauge = meter.createGauge('name');
-        gauge.getHandle(labelValues);
+        gauge.getHandle(labels);
         assert.strictEqual(gauge['_handles'].size, 1);
         gauge.clear();
         assert.strictEqual(gauge['_handles'].size, 0);
diff --git a/packages/opentelemetry-types/src/metrics/Metric.ts b/packages/opentelemetry-types/src/metrics/Metric.ts
index a34bd2d2f2..d26c9340b0 100644
--- a/packages/opentelemetry-types/src/metrics/Metric.ts
+++ b/packages/opentelemetry-types/src/metrics/Metric.ts
@@ -33,9 +33,6 @@ export interface MetricOptions {
    */
   unit?: string;
 
-  /** The list of label keys for the Metric. */
-  labelKeys?: string[];
-
   /** The map of constant labels for the Metric. */
   constantLabels?: Map<string, string>;
 
@@ -61,9 +58,9 @@ export interface Metric<T> {
    * Returns a Handle associated with specified label values.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for every operations.
-   * @param labelValues the list of label values.
+   * @param labels the object of label set.
    */
-  getHandle(labelValues: string[]): T;
+  getHandle(labels: LabelSet): T;
 
   /**
    * Returns a Handle for a metric with all labels not set.
@@ -72,9 +69,9 @@ export interface Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labelValues the list of label values.
+   * @param labels the object of label set.
    */
-  removeHandle(labelValues: string[]): void;
+  removeHandle(labels: LabelSet): void;
 
   /**
    * Clears all timeseries from the Metric.
@@ -86,3 +83,5 @@ export interface Metric<T> {
    */
   setCallback(fn: () => void): void;
 }
+
+export interface LabelSet {}

From 860fe6d525af67e11082e8bb6325cb1d95775994 Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Tue, 29 Oct 2019 10:02:05 -0700
Subject: [PATCH 02/13] fix: linting

---
 .../opentelemetry-core/src/metrics/NoopMeter.ts    |  2 +-
 .../test/metrics/NoopMeter.test.ts                 | 14 +++++---------
 packages/opentelemetry-metrics/test/Meter.test.ts  | 14 +++++++++++---
 3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/packages/opentelemetry-core/src/metrics/NoopMeter.ts b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
index 5cd17e93dd..b154b8396a 100644
--- a/packages/opentelemetry-core/src/metrics/NoopMeter.ts
+++ b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
@@ -23,7 +23,7 @@ import {
   MetricOptions,
   MeasureHandle,
   SpanContext,
-  LabelSet
+  LabelSet,
 } from '@opentelemetry/types';
 
 /**
diff --git a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
index 4999027e54..72d6064437 100644
--- a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
+++ b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
@@ -30,7 +30,9 @@ describe('NoopMeter', () => {
   it('should not crash', () => {
     const meter = new NoopMeter();
     const counter = meter.createCounter('some-name');
-    const labels: LabelSet = { 'key1': 'val1', 'key2': 'val2'};
+    const key1 = 'key1';
+    const key2 = 'key2';
+    const labels: LabelSet = { [key1]: 'val1', [key2]: 'val2' };
     // ensure NoopMetric does not crash.
     counter.setCallback(() => {
       assert.fail('callback occurred');
@@ -41,10 +43,7 @@ describe('NoopMeter', () => {
 
     // ensure the correct noop const is returned
     assert.strictEqual(counter, NOOP_COUNTER_METRIC);
-    assert.strictEqual(
-      counter.getHandle(labels),
-      NOOP_COUNTER_HANDLE
-    );
+    assert.strictEqual(counter.getHandle(labels), NOOP_COUNTER_HANDLE);
     assert.strictEqual(counter.getDefaultHandle(), NOOP_COUNTER_HANDLE);
     counter.clear();
 
@@ -63,10 +62,7 @@ describe('NoopMeter', () => {
     // ensure the correct noop const is returned
     assert.strictEqual(measure, NOOP_MEASURE_METRIC);
     assert.strictEqual(measure.getDefaultHandle(), NOOP_MEASURE_HANDLE);
-    assert.strictEqual(
-      measure.getHandle(labels),
-      NOOP_MEASURE_HANDLE
-    );
+    assert.strictEqual(measure.getHandle(labels), NOOP_MEASURE_HANDLE);
 
     const gauge = meter.createGauge('some-name');
     gauge.getDefaultHandle().set(1);
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index 4a0e80f7b3..059cc397a9 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -21,7 +21,8 @@ import { NoopLogger } from '@opentelemetry/core';
 
 describe('Meter', () => {
   let meter: Meter;
-  const labels: types.LabelSet = {'key': 'value'};
+  const key = 'key';
+  const labels: types.LabelSet = { [key]: 'value' };
   const hrTime: types.HrTime = [22, 400000000];
 
   beforeEach(() => {
@@ -58,7 +59,12 @@ describe('Meter', () => {
 
       it('should return the timeseries', () => {
         const counter = meter.createCounter('name');
-        const handle = counter.getHandle({'key1': 'value1', 'key2': 'value2'});
+        const key1 = 'key1';
+        const key2 = 'key2';
+        const handle = counter.getHandle({
+          [key1]: 'value1',
+          [key2]: 'value2',
+        });
         handle.add(20);
         assert.deepStrictEqual(handle.getTimeSeries(hrTime), {
           labelValues: [{ value: 'value1' }, { value: 'value2' }],
@@ -159,7 +165,9 @@ describe('Meter', () => {
 
       it('should return the timeseries', () => {
         const gauge = meter.createGauge('name');
-        const handle = gauge.getHandle({'k1': 'v1', 'k2': 'v2'});
+        const k1 = 'k1';
+        const k2 = 'k2';
+        const handle = gauge.getHandle({ [k1]: 'v1', [k2]: 'v2' });
         handle.set(150);
         assert.deepStrictEqual(handle.getTimeSeries(hrTime), {
           labelValues: [{ value: 'v1' }, { value: 'v2' }],

From 51ef29e876059637b58c8bc9f4b19140367dbf07 Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Tue, 29 Oct 2019 14:06:44 -0700
Subject: [PATCH 03/13] fix: doc strings

---
 packages/opentelemetry-core/src/metrics/NoopMeter.ts | 7 ++++---
 packages/opentelemetry-metrics/src/Handle.ts         | 5 ++---
 packages/opentelemetry-metrics/src/Metric.ts         | 6 +++---
 packages/opentelemetry-metrics/src/export/types.ts   | 2 +-
 packages/opentelemetry-types/src/metrics/Metric.ts   | 6 +++---
 5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/packages/opentelemetry-core/src/metrics/NoopMeter.ts b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
index b154b8396a..3f32107b56 100644
--- a/packages/opentelemetry-core/src/metrics/NoopMeter.ts
+++ b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
@@ -68,10 +68,10 @@ export class NoopMetric<T> implements Metric<T> {
     this._handle = handle;
   }
   /**
-   * Returns a Handle associated with specified label values.
+   * Returns a Handle associated with specified LabelSet.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for every operations.
-   * @param labels the object of label set.
+   * @param labels the LabelSet used to associate with this metric handle.
    */
   getHandle(labels: LabelSet): T {
     return this._handle;
@@ -86,9 +86,10 @@ export class NoopMetric<T> implements Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labels the object of label set.
+   * @param labels the LabelSet used to associate with this metric handle.
    */
   removeHandle(labels: LabelSet): void {
+    // @todo: implement this method
     return;
   }
 
diff --git a/packages/opentelemetry-metrics/src/Handle.ts b/packages/opentelemetry-metrics/src/Handle.ts
index 85ef3b1e98..04159630e2 100644
--- a/packages/opentelemetry-metrics/src/Handle.ts
+++ b/packages/opentelemetry-metrics/src/Handle.ts
@@ -19,8 +19,7 @@ import { TimeSeries } from './export/types';
 
 /**
  * CounterHandle allows the SDK to observe/record a single metric event. The
- * value of single handle in the `Counter` associated with specified label
- * values.
+ * value of single handle in the `Counter` associated with specified LabelSet.
  */
 export class CounterHandle implements types.CounterHandle {
   private _data = 0;
@@ -58,7 +57,7 @@ export class CounterHandle implements types.CounterHandle {
 
 /**
  * GaugeHandle allows the SDK to observe/record a single metric event. The
- * value of single handle in the `Gauge` associated with specified label values.
+ * value of single handle in the `Gauge` associated with specified LabelSet.
  */
 export class GaugeHandle implements types.GaugeHandle {
   private _data = 0;
diff --git a/packages/opentelemetry-metrics/src/Metric.ts b/packages/opentelemetry-metrics/src/Metric.ts
index 9befe98cb7..adff4f56de 100644
--- a/packages/opentelemetry-metrics/src/Metric.ts
+++ b/packages/opentelemetry-metrics/src/Metric.ts
@@ -33,10 +33,10 @@ export abstract class Metric<T> implements types.Metric<T> {
   }
 
   /**
-   * Returns a Handle associated with specified label values.
+   * Returns a Handle associated with specified LabelSet.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for each operation.
-   * @param labels the object of label set.
+   * @param labels the LabelSet used to associate with this metric handle.
    */
   getHandle(labels: types.LabelSet): T {
     const hash = hashLabelValues(Object.values(labels));
@@ -58,7 +58,7 @@ export abstract class Metric<T> implements types.Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labels the object of label set.
+   * @param labels the LabelSet used to associate with this metric handle.
    */
   removeHandle(labels: types.LabelSet): void {
     this._handles.delete(hashLabelValues(Object.values(labels)));
diff --git a/packages/opentelemetry-metrics/src/export/types.ts b/packages/opentelemetry-metrics/src/export/types.ts
index 12d31a7c0f..6b9eb6158c 100644
--- a/packages/opentelemetry-metrics/src/export/types.ts
+++ b/packages/opentelemetry-metrics/src/export/types.ts
@@ -124,7 +124,7 @@ export enum MetricDescriptorType {
 export interface TimeSeries {
   /**
    * The set of label values that uniquely identify this timeseries. Applies to
-   * all points. The order of label values must match that of label keys in the
+   * all points. The order of label values must match that of LabelSet keys in the
    * metric descriptor.
    */
   readonly labelValues: LabelValue[];
diff --git a/packages/opentelemetry-types/src/metrics/Metric.ts b/packages/opentelemetry-types/src/metrics/Metric.ts
index d26c9340b0..4bc523c0c6 100644
--- a/packages/opentelemetry-types/src/metrics/Metric.ts
+++ b/packages/opentelemetry-types/src/metrics/Metric.ts
@@ -55,10 +55,10 @@ export interface MetricOptions {
  */
 export interface Metric<T> {
   /**
-   * Returns a Handle associated with specified label values.
+   * Returns a Handle associated with specified LabelSet.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for every operations.
-   * @param labels the object of label set.
+   * @param labels the LabelSet used to associate with this metric handle.
    */
   getHandle(labels: LabelSet): T;
 
@@ -69,7 +69,7 @@ export interface Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labels the object of label set.
+   * @param labels the LabelSet used to associate with this metric handle.
    */
   removeHandle(labels: LabelSet): void;
 

From 3599b53cdebabc9367163a56bd38c07c47702daa Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Wed, 30 Oct 2019 14:37:49 -0700
Subject: [PATCH 04/13] fix: expose labels function in Meter

---
 .../src/metrics/NoopMeter.ts                  | 10 ++++++++--
 packages/opentelemetry-metrics/src/Meter.ts   | 13 ++++++++++++
 packages/opentelemetry-metrics/src/Metric.ts  |  4 ++--
 packages/opentelemetry-metrics/src/Utils.ts   |  2 +-
 .../opentelemetry-metrics/src/export/types.ts |  2 ++
 packages/opentelemetry-metrics/src/types.ts   |  4 ++++
 .../opentelemetry-metrics/test/Meter.test.ts  | 20 +++++++++++++++----
 .../opentelemetry-types/src/metrics/Meter.ts  | 10 +++++++++-
 .../opentelemetry-types/src/metrics/Metric.ts |  6 +++---
 9 files changed, 58 insertions(+), 13 deletions(-)

diff --git a/packages/opentelemetry-core/src/metrics/NoopMeter.ts b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
index 3f32107b56..34d8de0481 100644
--- a/packages/opentelemetry-core/src/metrics/NoopMeter.ts
+++ b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
@@ -59,6 +59,10 @@ export class NoopMeter implements Meter {
   createGauge(name: string, options?: MetricOptions): Metric<GaugeHandle> {
     return NOOP_GAUGE_METRIC;
   }
+
+  labels(labels: LabelSet): LabelSet {
+    return NOOP_METER;
+  }
 }
 
 export class NoopMetric<T> implements Metric<T> {
@@ -71,7 +75,7 @@ export class NoopMetric<T> implements Metric<T> {
    * Returns a Handle associated with specified LabelSet.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for every operations.
-   * @param labels the LabelSet used to associate with this metric handle.
+   * @param labels the canonicalized LabelSet used to associate with this metric handle.
    */
   getHandle(labels: LabelSet): T {
     return this._handle;
@@ -86,7 +90,7 @@ export class NoopMetric<T> implements Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labels the LabelSet used to associate with this metric handle.
+   * @param labels the canonicalized LabelSet used to associate with this metric handle.
    */
   removeHandle(labels: LabelSet): void {
     // @todo: implement this method
@@ -139,3 +143,5 @@ export const NOOP_MEASURE_HANDLE = new NoopMeasureHandle();
 export const NOOP_MEASURE_METRIC = new NoopMetric<MeasureHandle>(
   NOOP_MEASURE_HANDLE
 );
+
+export const NOOP_METER = {} as LabelSet;
diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index a882b5e048..896232ac4f 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -93,4 +93,17 @@ export class Meter implements types.Meter {
     };
     return new GaugeMetric(name, opt);
   }
+
+  /**
+   * Provide a pre-computed re-useable LabelSet by
+   * converting the unordered LabelSet into a canonicalized 
+   * set of lables, useful for pre-aggregation.
+   * @param labels user provided unordered LabelSet.
+   */
+  labels(labels: types.LabelSet): types.LabelSet {
+    return Object.keys(labels).sort().reduce((result, key) => {
+      result[key] = labels[key];
+      return result;
+    }, {} as types.LabelSet);
+  }
 }
diff --git a/packages/opentelemetry-metrics/src/Metric.ts b/packages/opentelemetry-metrics/src/Metric.ts
index adff4f56de..602a6c029b 100644
--- a/packages/opentelemetry-metrics/src/Metric.ts
+++ b/packages/opentelemetry-metrics/src/Metric.ts
@@ -36,7 +36,7 @@ export abstract class Metric<T> implements types.Metric<T> {
    * Returns a Handle associated with specified LabelSet.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for each operation.
-   * @param labels the LabelSet used to associate with this metric handle.
+   * @param labels the canonicalized LabelSet used to associate with this metric handle.
    */
   getHandle(labels: types.LabelSet): T {
     const hash = hashLabelValues(Object.values(labels));
@@ -58,7 +58,7 @@ export abstract class Metric<T> implements types.Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labels the LabelSet used to associate with this metric handle.
+   * @param labels the canonicalized LabelSet used to associate with this metric handle.
    */
   removeHandle(labels: types.LabelSet): void {
     this._handles.delete(hashLabelValues(Object.values(labels)));
diff --git a/packages/opentelemetry-metrics/src/Utils.ts b/packages/opentelemetry-metrics/src/Utils.ts
index 4fa4242cb7..71565a8d97 100644
--- a/packages/opentelemetry-metrics/src/Utils.ts
+++ b/packages/opentelemetry-metrics/src/Utils.ts
@@ -23,5 +23,5 @@ const COMMA_SEPARATOR = ',';
  * @returns The hashed label values string.
  */
 export function hashLabelValues(labelValues: string[]): string {
-  return labelValues.sort().join(COMMA_SEPARATOR);
+  return labelValues.join(COMMA_SEPARATOR);
 }
diff --git a/packages/opentelemetry-metrics/src/export/types.ts b/packages/opentelemetry-metrics/src/export/types.ts
index 6b9eb6158c..b9a3e3e424 100644
--- a/packages/opentelemetry-metrics/src/export/types.ts
+++ b/packages/opentelemetry-metrics/src/export/types.ts
@@ -61,6 +61,8 @@ export interface MetricDescriptor {
   readonly unit: string;
   /** MetricDescriptor type */
   readonly type: MetricDescriptorType;
+  /** The label keys associated with the metric descriptor. */
+  readonly labelKeys: string[];
   /** The label set associated with the metric descriptor. */
   readonly labels: LabelSet;
 }
diff --git a/packages/opentelemetry-metrics/src/types.ts b/packages/opentelemetry-metrics/src/types.ts
index b1e262bd5f..d4078bbfcf 100644
--- a/packages/opentelemetry-metrics/src/types.ts
+++ b/packages/opentelemetry-metrics/src/types.ts
@@ -28,6 +28,9 @@ export interface MetricOptions {
   /** The unit of the Metric values. */
   unit: string;
 
+  /** The list of label keys for the Metric. */
+  labelKeys: string[];
+
   /** The map of constant labels for the Metric. */
   constantLabels?: Map<string, string>;
 
@@ -60,4 +63,5 @@ export const DEFAULT_METRIC_OPTIONS = {
   disabled: false,
   description: '',
   unit: '1',
+  labelKeys: [],
 };
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index 059cc397a9..1ff73490a9 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -21,16 +21,28 @@ import { NoopLogger } from '@opentelemetry/core';
 
 describe('Meter', () => {
   let meter: Meter;
-  const key = 'key';
-  const labels: types.LabelSet = { [key]: 'value' };
+  const keya = 'keya';
+  const keyb = 'keyb';
+  let labels: types.LabelSet = { [keyb]: 'value2', [keya]: 'value1' };
   const hrTime: types.HrTime = [22, 400000000];
 
   beforeEach(() => {
     meter = new Meter({
       logger: new NoopLogger(),
     });
+    labels = meter.labels(labels);
   });
 
+  describe('#meter', () => {
+    it('should re-order labels to a canonicalized set', () => {
+      const orderedLabels: types.LabelSet = {
+        [keya]: 'value1',
+        [keyb]: 'value2'
+      }
+      assert.deepEqual(labels, orderedLabels);
+    });
+  });  
+
   describe('#counter', () => {
     it('should create a counter', () => {
       const counter = meter.createCounter('name');
@@ -124,7 +136,7 @@ describe('Meter', () => {
 
       it('should not fail when removing non existing handle', () => {
         const counter = meter.createCounter('name');
-        counter.removeHandle([]);
+        counter.removeHandle({});
       });
 
       it('should clear all handles', () => {
@@ -227,7 +239,7 @@ describe('Meter', () => {
 
       it('should not fail when removing non existing handle', () => {
         const gauge = meter.createGauge('name');
-        gauge.removeHandle([]);
+        gauge.removeHandle({});
       });
 
       it('should clear all handles', () => {
diff --git a/packages/opentelemetry-types/src/metrics/Meter.ts b/packages/opentelemetry-types/src/metrics/Meter.ts
index 15f03688b6..7d71b43940 100644
--- a/packages/opentelemetry-types/src/metrics/Meter.ts
+++ b/packages/opentelemetry-types/src/metrics/Meter.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { Metric, MetricOptions } from './Metric';
+import { Metric, MetricOptions, LabelSet } from './Metric';
 import { CounterHandle, GaugeHandle, MeasureHandle } from './Handle';
 
 /**
@@ -58,4 +58,12 @@ export interface Meter {
    * @param [options] the metric options.
    */
   createGauge(name: string, options?: MetricOptions): Metric<GaugeHandle>;
+
+  /**
+   * Provide a pre-computed re-useable LabelSet by
+   * converting the unordered LabelSet into a canonicalized 
+   * set of lables, useful for pre-aggregation.
+   * @param labels user provided unordered LabelSet.
+   */
+  labels(labels: LabelSet): LabelSet;
 }
diff --git a/packages/opentelemetry-types/src/metrics/Metric.ts b/packages/opentelemetry-types/src/metrics/Metric.ts
index 4bc523c0c6..7ab9fc75fc 100644
--- a/packages/opentelemetry-types/src/metrics/Metric.ts
+++ b/packages/opentelemetry-types/src/metrics/Metric.ts
@@ -58,7 +58,7 @@ export interface Metric<T> {
    * Returns a Handle associated with specified LabelSet.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for every operations.
-   * @param labels the LabelSet used to associate with this metric handle.
+   * @param labels the canonicalized LabelSet used to associate with this metric handle.
    */
   getHandle(labels: LabelSet): T;
 
@@ -69,7 +69,7 @@ export interface Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labels the LabelSet used to associate with this metric handle.
+   * @param labels the canonicalized LabelSet used to associate with this metric handle.
    */
   removeHandle(labels: LabelSet): void;
 
@@ -84,4 +84,4 @@ export interface Metric<T> {
   setCallback(fn: () => void): void;
 }
 
-export interface LabelSet {}
+export type LabelSet = Record<string, string>;

From 05d1c6312970ce0d3a9c2cea4a2e7fdd5ba821e5 Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Wed, 30 Oct 2019 15:00:15 -0700
Subject: [PATCH 05/13] fix: linting

---
 packages/opentelemetry-metrics/src/Meter.ts       | 15 ++++++++++-----
 packages/opentelemetry-metrics/test/Meter.test.ts |  6 +++---
 packages/opentelemetry-types/src/metrics/Meter.ts |  2 +-
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index 896232ac4f..29ff7ca256 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -96,14 +96,19 @@ export class Meter implements types.Meter {
 
   /**
    * Provide a pre-computed re-useable LabelSet by
-   * converting the unordered LabelSet into a canonicalized 
+   * converting the unordered LabelSet into a canonicalized
    * set of lables, useful for pre-aggregation.
    * @param labels user provided unordered LabelSet.
    */
   labels(labels: types.LabelSet): types.LabelSet {
-    return Object.keys(labels).sort().reduce((result, key) => {
-      result[key] = labels[key];
-      return result;
-    }, {} as types.LabelSet);
+    return Object.keys(labels)
+      .sort()
+      .reduce(
+        (result, key) => {
+          result[key] = labels[key];
+          return result;
+        },
+        {} as types.LabelSet
+      );
   }
 }
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index 1ff73490a9..da406a5cb4 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -37,11 +37,11 @@ describe('Meter', () => {
     it('should re-order labels to a canonicalized set', () => {
       const orderedLabels: types.LabelSet = {
         [keya]: 'value1',
-        [keyb]: 'value2'
-      }
+        [keyb]: 'value2',
+      };
       assert.deepEqual(labels, orderedLabels);
     });
-  });  
+  });
 
   describe('#counter', () => {
     it('should create a counter', () => {
diff --git a/packages/opentelemetry-types/src/metrics/Meter.ts b/packages/opentelemetry-types/src/metrics/Meter.ts
index 7d71b43940..56c870dd3b 100644
--- a/packages/opentelemetry-types/src/metrics/Meter.ts
+++ b/packages/opentelemetry-types/src/metrics/Meter.ts
@@ -61,7 +61,7 @@ export interface Meter {
 
   /**
    * Provide a pre-computed re-useable LabelSet by
-   * converting the unordered LabelSet into a canonicalized 
+   * converting the unordered LabelSet into a canonicalized
    * set of lables, useful for pre-aggregation.
    * @param labels user provided unordered LabelSet.
    */

From 821ad672b10e5c55a33714bd974175913d13cb7d Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Thu, 31 Oct 2019 11:29:42 -0700
Subject: [PATCH 06/13] fix: address comments

---
 packages/opentelemetry-core/src/metrics/NoopMeter.ts | 4 ++--
 packages/opentelemetry-metrics/src/export/types.ts   | 4 +---
 packages/opentelemetry-types/src/metrics/Metric.ts   | 3 +++
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/packages/opentelemetry-core/src/metrics/NoopMeter.ts b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
index 34d8de0481..6c56e29863 100644
--- a/packages/opentelemetry-core/src/metrics/NoopMeter.ts
+++ b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
@@ -61,7 +61,7 @@ export class NoopMeter implements Meter {
   }
 
   labels(labels: LabelSet): LabelSet {
-    return NOOP_METER;
+    return NOOP_LABEL_SET;
   }
 }
 
@@ -144,4 +144,4 @@ export const NOOP_MEASURE_METRIC = new NoopMetric<MeasureHandle>(
   NOOP_MEASURE_HANDLE
 );
 
-export const NOOP_METER = {} as LabelSet;
+export const NOOP_LABEL_SET = {} as LabelSet;
diff --git a/packages/opentelemetry-metrics/src/export/types.ts b/packages/opentelemetry-metrics/src/export/types.ts
index b9a3e3e424..c6aa9c08c8 100644
--- a/packages/opentelemetry-metrics/src/export/types.ts
+++ b/packages/opentelemetry-metrics/src/export/types.ts
@@ -22,7 +22,7 @@
  * opentelemetry-proto/opentelemetry/proto/metrics/v1/metrics.proto
  */
 
-import { HrTime, LabelSet } from '@opentelemetry/types';
+import { HrTime } from '@opentelemetry/types';
 import { Resource, ExportResult } from '@opentelemetry/base';
 
 export interface ReadableMetric {
@@ -63,8 +63,6 @@ export interface MetricDescriptor {
   readonly type: MetricDescriptorType;
   /** The label keys associated with the metric descriptor. */
   readonly labelKeys: string[];
-  /** The label set associated with the metric descriptor. */
-  readonly labels: LabelSet;
 }
 
 /**
diff --git a/packages/opentelemetry-types/src/metrics/Metric.ts b/packages/opentelemetry-types/src/metrics/Metric.ts
index 7ab9fc75fc..5e13b81d93 100644
--- a/packages/opentelemetry-types/src/metrics/Metric.ts
+++ b/packages/opentelemetry-types/src/metrics/Metric.ts
@@ -33,6 +33,9 @@ export interface MetricOptions {
    */
   unit?: string;
 
+  /** The list of label keys for the Metric. */
+  labelKeys?: string[];
+
   /** The map of constant labels for the Metric. */
   constantLabels?: Map<string, string>;
 

From dea892cdfce287e0eaedd277f3fce12547370538 Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Fri, 1 Nov 2019 17:30:55 -0700
Subject: [PATCH 07/13] fix: udpate LabelSet logic

---
 .../src/metrics/NoopMeter.ts                  |  3 +-
 .../test/metrics/NoopMeter.test.ts            | 18 ++---
 packages/opentelemetry-metrics/src/Handle.ts  | 12 ++--
 packages/opentelemetry-metrics/src/Meter.ts   | 31 +++++----
 packages/opentelemetry-metrics/src/Metric.ts  | 29 ++++----
 packages/opentelemetry-metrics/src/Utils.ts   | 12 ----
 packages/opentelemetry-metrics/src/types.ts   | 12 +++-
 .../opentelemetry-metrics/test/Meter.test.ts  | 66 +++++++++----------
 .../opentelemetry-types/src/metrics/Meter.ts  | 11 ++--
 .../opentelemetry-types/src/metrics/Metric.ts | 13 +++-
 10 files changed, 113 insertions(+), 94 deletions(-)

diff --git a/packages/opentelemetry-core/src/metrics/NoopMeter.ts b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
index 6c56e29863..9f354cbaa0 100644
--- a/packages/opentelemetry-core/src/metrics/NoopMeter.ts
+++ b/packages/opentelemetry-core/src/metrics/NoopMeter.ts
@@ -24,6 +24,7 @@ import {
   MeasureHandle,
   SpanContext,
   LabelSet,
+  Labels,
 } from '@opentelemetry/types';
 
 /**
@@ -60,7 +61,7 @@ export class NoopMeter implements Meter {
     return NOOP_GAUGE_METRIC;
   }
 
-  labels(labels: LabelSet): LabelSet {
+  labels(labels: Labels): LabelSet {
     return NOOP_LABEL_SET;
   }
 }
diff --git a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
index 72d6064437..be6324d1b2 100644
--- a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
+++ b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
@@ -24,26 +24,26 @@ import {
   NOOP_MEASURE_HANDLE,
   NOOP_MEASURE_METRIC,
 } from '../../src/metrics/NoopMeter';
-import { LabelSet } from '@opentelemetry/types';
+import { Labels } from '@opentelemetry/types';
 
 describe('NoopMeter', () => {
   it('should not crash', () => {
     const meter = new NoopMeter();
     const counter = meter.createCounter('some-name');
-    const key1 = 'key1';
-    const key2 = 'key2';
-    const labels: LabelSet = { [key1]: 'val1', [key2]: 'val2' };
+    const labels = {} as Labels;
+    const labelSet = meter.labels(labels);
+    
     // ensure NoopMetric does not crash.
     counter.setCallback(() => {
       assert.fail('callback occurred');
     });
-    counter.getHandle(labels).add(1);
+    counter.getHandle(labelSet).add(1);
     counter.getDefaultHandle().add(1);
-    counter.removeHandle(labels);
+    counter.removeHandle(labelSet);
 
     // ensure the correct noop const is returned
     assert.strictEqual(counter, NOOP_COUNTER_METRIC);
-    assert.strictEqual(counter.getHandle(labels), NOOP_COUNTER_HANDLE);
+    assert.strictEqual(counter.getHandle(labelSet), NOOP_COUNTER_HANDLE);
     assert.strictEqual(counter.getDefaultHandle(), NOOP_COUNTER_HANDLE);
     counter.clear();
 
@@ -62,7 +62,7 @@ describe('NoopMeter', () => {
     // ensure the correct noop const is returned
     assert.strictEqual(measure, NOOP_MEASURE_METRIC);
     assert.strictEqual(measure.getDefaultHandle(), NOOP_MEASURE_HANDLE);
-    assert.strictEqual(measure.getHandle(labels), NOOP_MEASURE_HANDLE);
+    assert.strictEqual(measure.getHandle(labelSet), NOOP_MEASURE_HANDLE);
 
     const gauge = meter.createGauge('some-name');
     gauge.getDefaultHandle().set(1);
@@ -70,7 +70,7 @@ describe('NoopMeter', () => {
     // ensure the correct noop const is returned
     assert.strictEqual(gauge, NOOP_GAUGE_METRIC);
     assert.strictEqual(gauge.getDefaultHandle(), NOOP_GAUGE_HANDLE);
-    assert.strictEqual(gauge.getHandle(labels), NOOP_GAUGE_HANDLE);
+    assert.strictEqual(gauge.getHandle(labelSet), NOOP_GAUGE_HANDLE);
 
     const options = {
       component: 'tests',
diff --git a/packages/opentelemetry-metrics/src/Handle.ts b/packages/opentelemetry-metrics/src/Handle.ts
index 04159630e2..0c0760d13e 100644
--- a/packages/opentelemetry-metrics/src/Handle.ts
+++ b/packages/opentelemetry-metrics/src/Handle.ts
@@ -27,7 +27,7 @@ export class CounterHandle implements types.CounterHandle {
   constructor(
     private readonly _disabled: boolean,
     private readonly _monotonic: boolean,
-    private readonly _labels: types.LabelSet,
+    private readonly _labelSet: types.LabelSet,
     private readonly _logger: types.Logger
   ) {}
 
@@ -49,7 +49,9 @@ export class CounterHandle implements types.CounterHandle {
    */
   getTimeSeries(timestamp: types.HrTime): TimeSeries {
     return {
-      labelValues: Object.values(this._labels).map(value => ({ value })),
+      labelValues: Object.values(this._labelSet.labels).map(value => ({
+        value,
+      })),
       points: [{ value: this._data, timestamp }],
     };
   }
@@ -65,7 +67,7 @@ export class GaugeHandle implements types.GaugeHandle {
   constructor(
     private readonly _disabled: boolean,
     private readonly _monotonic: boolean,
-    private readonly _labels: types.LabelSet,
+    private readonly _labelSet: types.LabelSet,
     private readonly _logger: types.Logger
   ) {}
 
@@ -87,7 +89,9 @@ export class GaugeHandle implements types.GaugeHandle {
    */
   getTimeSeries(timestamp: types.HrTime): TimeSeries {
     return {
-      labelValues: Object.values(this._labels).map(value => ({ value })),
+      labelValues: Object.values(this._labelSet.labels).map(value => ({
+        value,
+      })),
       points: [{ value: this._data, timestamp }],
     };
   }
diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index 46203d58fa..7c45799585 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -27,6 +27,7 @@ import {
   DEFAULT_METRIC_OPTIONS,
   DEFAULT_CONFIG,
   MeterConfig,
+  LabelSet,
 } from './types';
 
 /**
@@ -118,20 +119,24 @@ export class Meter implements types.Meter {
 
   /**
    * Provide a pre-computed re-useable LabelSet by
-   * converting the unordered LabelSet into a canonicalized
-   * set of lables, useful for pre-aggregation.
-   * @param labels user provided unordered LabelSet.
+   * converting the unordered labels into a canonicalized
+   * set of lables with a unique labelSetKey, useful for pre-aggregation.
+   * @param labels user provided unordered Labels.
    */
-  labels(labels: types.LabelSet): types.LabelSet {
-    return Object.keys(labels)
-      .sort()
-      .reduce(
-        (result, key) => {
-          result[key] = labels[key];
-          return result;
-        },
-        {} as types.LabelSet
-      );
+  labels(labels: types.Labels): types.LabelSet {
+    let keys = Object.keys(labels).sort();
+    let labelSetKey = keys.reduce((result, key) => {
+      if (result.length > 2) {
+        result += ',';
+      }
+      result = result + key + ':' + labels[key];
+      return result;
+    }, '|#');
+    let sortedLabels = {} as types.Labels;
+    keys.forEach(key => {
+      sortedLabels[key] = labels[key];
+    });
+    return new LabelSet(labelSetKey, sortedLabels);
   }
 
   /**
diff --git a/packages/opentelemetry-metrics/src/Metric.ts b/packages/opentelemetry-metrics/src/Metric.ts
index 602a6c029b..f6f4291409 100644
--- a/packages/opentelemetry-metrics/src/Metric.ts
+++ b/packages/opentelemetry-metrics/src/Metric.ts
@@ -15,7 +15,6 @@
  */
 
 import * as types from '@opentelemetry/types';
-import { hashLabelValues } from './Utils';
 import { CounterHandle, GaugeHandle } from './Handle';
 import { MetricOptions } from './types';
 
@@ -36,14 +35,14 @@ export abstract class Metric<T> implements types.Metric<T> {
    * Returns a Handle associated with specified LabelSet.
    * It is recommended to keep a reference to the Handle instead of always
    * calling this method for each operation.
-   * @param labels the canonicalized LabelSet used to associate with this metric handle.
+   * @param labelSet the canonicalized LabelSet used to associate with this metric handle.
    */
-  getHandle(labels: types.LabelSet): T {
-    const hash = hashLabelValues(Object.values(labels));
-    if (this._handles.has(hash)) return this._handles.get(hash)!;
+  getHandle(labelSet: types.LabelSet): T {
+    if (this._handles.has(labelSet.labelSetKey))
+      return this._handles.get(labelSet.labelSetKey)!;
 
-    const handle = this._makeHandle(labels);
-    this._handles.set(hash, handle);
+    const handle = this._makeHandle(labelSet);
+    this._handles.set(labelSet.labelSetKey, handle);
     return handle;
   }
 
@@ -58,10 +57,10 @@ export abstract class Metric<T> implements types.Metric<T> {
 
   /**
    * Removes the Handle from the metric, if it is present.
-   * @param labels the canonicalized LabelSet used to associate with this metric handle.
+   * @param labelSet the canonicalized LabelSet used to associate with this metric handle.
    */
-  removeHandle(labels: types.LabelSet): void {
-    this._handles.delete(hashLabelValues(Object.values(labels)));
+  removeHandle(labelSet: types.LabelSet): void {
+    this._handles.delete(labelSet.labelSetKey);
   }
 
   /**
@@ -77,7 +76,7 @@ export abstract class Metric<T> implements types.Metric<T> {
     return;
   }
 
-  protected abstract _makeHandle(labels: types.LabelSet): T;
+  protected abstract _makeHandle(labelSet: types.LabelSet): T;
 }
 
 /** This is a SDK implementation of Counter Metric. */
@@ -85,11 +84,11 @@ export class CounterMetric extends Metric<CounterHandle> {
   constructor(name: string, options: MetricOptions) {
     super(name, options);
   }
-  protected _makeHandle(labels: types.LabelSet): CounterHandle {
+  protected _makeHandle(labelSet: types.LabelSet): CounterHandle {
     return new CounterHandle(
       this._disabled,
       this._monotonic,
-      labels,
+      labelSet,
       this._logger
     );
   }
@@ -100,11 +99,11 @@ export class GaugeMetric extends Metric<GaugeHandle> {
   constructor(name: string, options: MetricOptions) {
     super(name, options);
   }
-  protected _makeHandle(labels: types.LabelSet): GaugeHandle {
+  protected _makeHandle(labelSet: types.LabelSet): GaugeHandle {
     return new GaugeHandle(
       this._disabled,
       this._monotonic,
-      labels,
+      labelSet,
       this._logger
     );
   }
diff --git a/packages/opentelemetry-metrics/src/Utils.ts b/packages/opentelemetry-metrics/src/Utils.ts
index 71565a8d97..ae225f6b52 100644
--- a/packages/opentelemetry-metrics/src/Utils.ts
+++ b/packages/opentelemetry-metrics/src/Utils.ts
@@ -13,15 +13,3 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-const COMMA_SEPARATOR = ',';
-
-/**
- * Returns a string(comma separated) from the list of label values.
- *
- * @param labelValues The list of the label values.
- * @returns The hashed label values string.
- */
-export function hashLabelValues(labelValues: string[]): string {
-  return labelValues.join(COMMA_SEPARATOR);
-}
diff --git a/packages/opentelemetry-metrics/src/types.ts b/packages/opentelemetry-metrics/src/types.ts
index d4078bbfcf..5f637d31fd 100644
--- a/packages/opentelemetry-metrics/src/types.ts
+++ b/packages/opentelemetry-metrics/src/types.ts
@@ -15,7 +15,7 @@
  */
 
 import { LogLevel } from '@opentelemetry/core';
-import { Logger } from '@opentelemetry/types';
+import { Logger, Labels } from '@opentelemetry/types';
 
 /** Options needed for SDK metric creation. */
 export interface MetricOptions {
@@ -65,3 +65,13 @@ export const DEFAULT_METRIC_OPTIONS = {
   unit: '1',
   labelKeys: [],
 };
+
+export class LabelSet implements LabelSet {
+  labelSetKey: string;
+  labels: Labels;
+
+  constructor(labelSetKey: string, labels: Labels) {
+    this.labelSetKey = labelSetKey;
+    this.labels = labels;
+  }
+}
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index e3a740259a..4ceb97e4e2 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -18,28 +18,31 @@ import * as assert from 'assert';
 import { Meter, Metric, CounterMetric, GaugeMetric } from '../src';
 import * as types from '@opentelemetry/types';
 import { NoopLogger, NoopMetric } from '@opentelemetry/core';
+import { LabelSet } from '../src/types';
 
 describe('Meter', () => {
   let meter: Meter;
   const keya = 'keya';
   const keyb = 'keyb';
-  let labels: types.LabelSet = { [keyb]: 'value2', [keya]: 'value1' };
+  let labels: types.Labels = { [keyb]: 'value2', [keya]: 'value1' };
+  let labelSet: types.LabelSet;
   const hrTime: types.HrTime = [22, 400000000];
 
   beforeEach(() => {
     meter = new Meter({
       logger: new NoopLogger(),
     });
-    labels = meter.labels(labels);
+    labelSet = meter.labels(labels);
   });
 
   describe('#meter', () => {
     it('should re-order labels to a canonicalized set', () => {
-      const orderedLabels: types.LabelSet = {
+      const orderedLabels: types.Labels = {
         [keya]: 'value1',
         [keyb]: 'value2',
       };
-      assert.deepEqual(labels, orderedLabels);
+      const labelSetKey = '|#keya:value1,keyb:value2';
+      assert.deepEqual(labelSet, new LabelSet(labelSetKey, orderedLabels));
     });
   });
 
@@ -62,7 +65,7 @@ describe('Meter', () => {
     describe('.getHandle()', () => {
       it('should create a counter handle', () => {
         const counter = meter.createCounter('name') as CounterMetric;
-        const handle = counter.getHandle(labels);
+        const handle = counter.getHandle(labelSet);
         handle.add(10);
         assert.strictEqual(handle['_data'], 10);
         handle.add(10);
@@ -71,12 +74,7 @@ describe('Meter', () => {
 
       it('should return the timeseries', () => {
         const counter = meter.createCounter('name') as CounterMetric;
-        const key1 = 'key1';
-        const key2 = 'key2';
-        const handle = counter.getHandle({
-          [key1]: 'value1',
-          [key2]: 'value2',
-        });
+        const handle = counter.getHandle(labelSet);
         handle.add(20);
         assert.deepStrictEqual(handle.getTimeSeries(hrTime), {
           labelValues: [{ value: 'value1' }, { value: 'value2' }],
@@ -86,7 +84,7 @@ describe('Meter', () => {
 
       it('should add positive values by default', () => {
         const counter = meter.createCounter('name') as CounterMetric;
-        const handle = counter.getHandle(labels);
+        const handle = counter.getHandle(labelSet);
         handle.add(10);
         assert.strictEqual(handle['_data'], 10);
         handle.add(-100);
@@ -97,7 +95,7 @@ describe('Meter', () => {
         const counter = meter.createCounter('name', {
           disabled: true,
         }) as CounterMetric;
-        const handle = counter.getHandle(labels);
+        const handle = counter.getHandle(labelSet);
         handle.add(10);
         assert.strictEqual(handle['_data'], 0);
       });
@@ -106,16 +104,16 @@ describe('Meter', () => {
         const counter = meter.createCounter('name', {
           monotonic: false,
         }) as CounterMetric;
-        const handle = counter.getHandle(labels);
+        const handle = counter.getHandle(labelSet);
         handle.add(-10);
         assert.strictEqual(handle['_data'], -10);
       });
 
       it('should return same handle on same label values', () => {
         const counter = meter.createCounter('name') as CounterMetric;
-        const handle = counter.getHandle(labels);
+        const handle = counter.getHandle(labelSet);
         handle.add(10);
-        const handle1 = counter.getHandle(labels);
+        const handle1 = counter.getHandle(labelSet);
         handle1.add(10);
         assert.strictEqual(handle['_data'], 20);
         assert.strictEqual(handle, handle1);
@@ -125,23 +123,23 @@ describe('Meter', () => {
     describe('.removeHandle()', () => {
       it('should remove a counter handle', () => {
         const counter = meter.createCounter('name') as CounterMetric;
-        const handle = counter.getHandle(labels);
+        const handle = counter.getHandle(labelSet);
         assert.strictEqual(counter['_handles'].size, 1);
-        counter.removeHandle(labels);
+        counter.removeHandle(labelSet);
         assert.strictEqual(counter['_handles'].size, 0);
-        const handle1 = counter.getHandle(labels);
+        const handle1 = counter.getHandle(labelSet);
         assert.strictEqual(counter['_handles'].size, 1);
         assert.notStrictEqual(handle, handle1);
       });
 
       it('should not fail when removing non existing handle', () => {
         const counter = meter.createCounter('name');
-        counter.removeHandle({});
+        counter.removeHandle(new LabelSet('', {}));
       });
 
       it('should clear all handles', () => {
         const counter = meter.createCounter('name') as CounterMetric;
-        counter.getHandle(labels);
+        counter.getHandle(labelSet);
         assert.strictEqual(counter['_handles'].size, 1);
         counter.clear();
         assert.strictEqual(counter['_handles'].size, 0);
@@ -196,7 +194,7 @@ describe('Meter', () => {
     describe('.getHandle()', () => {
       it('should create a gauge handle', () => {
         const gauge = meter.createGauge('name') as GaugeMetric;
-        const handle = gauge.getHandle(labels);
+        const handle = gauge.getHandle(labelSet);
         handle.set(10);
         assert.strictEqual(handle['_data'], 10);
         handle.set(250);
@@ -207,7 +205,9 @@ describe('Meter', () => {
         const gauge = meter.createGauge('name') as GaugeMetric;
         const k1 = 'k1';
         const k2 = 'k2';
-        const handle = gauge.getHandle({ [k1]: 'v1', [k2]: 'v2' });
+        const labels = { [k1]: 'v1', [k2]: 'v2' };
+        const LabelSet2 = new LabelSet('|#k1:v1,k2:v2', labels);
+        const handle = gauge.getHandle(LabelSet2);
         handle.set(150);
         assert.deepStrictEqual(handle.getTimeSeries(hrTime), {
           labelValues: [{ value: 'v1' }, { value: 'v2' }],
@@ -217,7 +217,7 @@ describe('Meter', () => {
 
       it('should go up and down by default', () => {
         const gauge = meter.createGauge('name') as GaugeMetric;
-        const handle = gauge.getHandle(labels);
+        const handle = gauge.getHandle(labelSet);
         handle.set(10);
         assert.strictEqual(handle['_data'], 10);
         handle.set(-100);
@@ -228,7 +228,7 @@ describe('Meter', () => {
         const gauge = meter.createGauge('name', {
           disabled: true,
         }) as GaugeMetric;
-        const handle = gauge.getHandle(labels);
+        const handle = gauge.getHandle(labelSet);
         handle.set(10);
         assert.strictEqual(handle['_data'], 0);
       });
@@ -237,16 +237,16 @@ describe('Meter', () => {
         const gauge = meter.createGauge('name', {
           monotonic: true,
         }) as GaugeMetric;
-        const handle = gauge.getHandle(labels);
+        const handle = gauge.getHandle(labelSet);
         handle.set(-10);
         assert.strictEqual(handle['_data'], 0);
       });
 
       it('should return same handle on same label values', () => {
         const gauge = meter.createGauge('name') as GaugeMetric;
-        const handle = gauge.getHandle(labels);
+        const handle = gauge.getHandle(labelSet);
         handle.set(10);
-        const handle1 = gauge.getHandle(labels);
+        const handle1 = gauge.getHandle(labelSet);
         handle1.set(10);
         assert.strictEqual(handle['_data'], 10);
         assert.strictEqual(handle, handle1);
@@ -256,23 +256,23 @@ describe('Meter', () => {
     describe('.removeHandle()', () => {
       it('should remove the gauge handle', () => {
         const gauge = meter.createGauge('name') as GaugeMetric;
-        const handle = gauge.getHandle(labels);
+        const handle = gauge.getHandle(labelSet);
         assert.strictEqual(gauge['_handles'].size, 1);
-        gauge.removeHandle(labels);
+        gauge.removeHandle(labelSet);
         assert.strictEqual(gauge['_handles'].size, 0);
-        const handle1 = gauge.getHandle(labels);
+        const handle1 = gauge.getHandle(labelSet);
         assert.strictEqual(gauge['_handles'].size, 1);
         assert.notStrictEqual(handle, handle1);
       });
 
       it('should not fail when removing non existing handle', () => {
         const gauge = meter.createGauge('name');
-        gauge.removeHandle({});
+        gauge.removeHandle(new LabelSet('', {}));
       });
 
       it('should clear all handles', () => {
         const gauge = meter.createGauge('name') as GaugeMetric;
-        gauge.getHandle(labels);
+        gauge.getHandle(labelSet);
         assert.strictEqual(gauge['_handles'].size, 1);
         gauge.clear();
         assert.strictEqual(gauge['_handles'].size, 0);
diff --git a/packages/opentelemetry-types/src/metrics/Meter.ts b/packages/opentelemetry-types/src/metrics/Meter.ts
index 56c870dd3b..cb0827b4dd 100644
--- a/packages/opentelemetry-types/src/metrics/Meter.ts
+++ b/packages/opentelemetry-types/src/metrics/Meter.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { Metric, MetricOptions, LabelSet } from './Metric';
+import { Metric, MetricOptions, Labels, LabelSet } from './Metric';
 import { CounterHandle, GaugeHandle, MeasureHandle } from './Handle';
 
 /**
@@ -61,9 +61,10 @@ export interface Meter {
 
   /**
    * Provide a pre-computed re-useable LabelSet by
-   * converting the unordered LabelSet into a canonicalized
-   * set of lables, useful for pre-aggregation.
-   * @param labels user provided unordered LabelSet.
+   * converting the unordered labels into a canonicalized
+   * set of lables with a unique labelSetKey, useful for pre-aggregation.
+   * @param labels user provided unordered Labels.
    */
-  labels(labels: LabelSet): LabelSet;
+  labels(labels: Labels): LabelSet;
 }
+
diff --git a/packages/opentelemetry-types/src/metrics/Metric.ts b/packages/opentelemetry-types/src/metrics/Metric.ts
index 5e13b81d93..272f5705d1 100644
--- a/packages/opentelemetry-types/src/metrics/Metric.ts
+++ b/packages/opentelemetry-types/src/metrics/Metric.ts
@@ -87,4 +87,15 @@ export interface Metric<T> {
   setCallback(fn: () => void): void;
 }
 
-export type LabelSet = Record<string, string>;
+/**
+ * key-value pairs passed by the user.
+ */
+export type Labels = Record<string, string>;
+
+/**
+ * Canonicalized labels with an unique string labelSetKey.
+ */
+export interface LabelSet {
+  labelSetKey: string;
+  labels: Labels;
+}

From 2a7e0935da614f4b4b3a19d6957af8afd7d1d76e Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Fri, 1 Nov 2019 17:39:43 -0700
Subject: [PATCH 08/13] fix: linting

---
 packages/opentelemetry-core/test/metrics/NoopMeter.test.ts | 2 +-
 packages/opentelemetry-types/src/metrics/Meter.ts          | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
index be6324d1b2..38294975f4 100644
--- a/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
+++ b/packages/opentelemetry-core/test/metrics/NoopMeter.test.ts
@@ -32,7 +32,7 @@ describe('NoopMeter', () => {
     const counter = meter.createCounter('some-name');
     const labels = {} as Labels;
     const labelSet = meter.labels(labels);
-    
+
     // ensure NoopMetric does not crash.
     counter.setCallback(() => {
       assert.fail('callback occurred');
diff --git a/packages/opentelemetry-types/src/metrics/Meter.ts b/packages/opentelemetry-types/src/metrics/Meter.ts
index cb0827b4dd..633b0d3645 100644
--- a/packages/opentelemetry-types/src/metrics/Meter.ts
+++ b/packages/opentelemetry-types/src/metrics/Meter.ts
@@ -67,4 +67,3 @@ export interface Meter {
    */
   labels(labels: Labels): LabelSet;
 }
-

From 9e9fc2768eb75b1474f8227932716418e130ab88 Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Mon, 4 Nov 2019 14:35:21 -0800
Subject: [PATCH 09/13] fix: address comments

---
 .../src/{Utils.ts => LabelSet.ts}                 | 15 +++++++++++++++
 packages/opentelemetry-metrics/src/Meter.ts       |  2 +-
 packages/opentelemetry-metrics/src/types.ts       | 12 +-----------
 packages/opentelemetry-metrics/test/Meter.test.ts |  2 +-
 4 files changed, 18 insertions(+), 13 deletions(-)
 rename packages/opentelemetry-metrics/src/{Utils.ts => LabelSet.ts} (65%)

diff --git a/packages/opentelemetry-metrics/src/Utils.ts b/packages/opentelemetry-metrics/src/LabelSet.ts
similarity index 65%
rename from packages/opentelemetry-metrics/src/Utils.ts
rename to packages/opentelemetry-metrics/src/LabelSet.ts
index ae225f6b52..67d6aa7ab1 100644
--- a/packages/opentelemetry-metrics/src/Utils.ts
+++ b/packages/opentelemetry-metrics/src/LabelSet.ts
@@ -13,3 +13,18 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+import * as types from '@opentelemetry/types';
+
+/**
+ * Canonicalized labels with an unique string encoded.
+ */
+export class LabelSet implements types.LabelSet {
+  encoded: string;
+  labels: types.Labels;
+
+  constructor(encoded: string, labels: types.Labels) {
+    this.encoded = encoded;
+    this.labels = labels;
+  }
+}
diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index 579b8edbb8..adbd9221d7 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -28,9 +28,9 @@ import {
   DEFAULT_METRIC_OPTIONS,
   DEFAULT_CONFIG,
   MeterConfig,
-  LabelSet,
 } from './types';
 import { ReadableMetric } from './export/types';
+import { LabelSet } from './LabelSet';
 
 /**
  * Meter is an implementation of the {@link Meter} interface.
diff --git a/packages/opentelemetry-metrics/src/types.ts b/packages/opentelemetry-metrics/src/types.ts
index 06692b8a50..a20ef0afd9 100644
--- a/packages/opentelemetry-metrics/src/types.ts
+++ b/packages/opentelemetry-metrics/src/types.ts
@@ -15,7 +15,7 @@
  */
 
 import { LogLevel } from '@opentelemetry/core';
-import { Logger, ValueType, Labels } from '@opentelemetry/types';
+import { Logger, ValueType } from '@opentelemetry/types';
 
 /** Options needed for SDK metric creation. */
 export interface MetricOptions {
@@ -69,13 +69,3 @@ export const DEFAULT_METRIC_OPTIONS = {
   labelKeys: [],
   valueType: ValueType.DOUBLE,
 };
-
-export class LabelSet implements LabelSet {
-  encoded: string;
-  labels: Labels;
-
-  constructor(encoded: string, labels: Labels) {
-    this.encoded = encoded;
-    this.labels = labels;
-  }
-}
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index e078090e59..231c697273 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -23,7 +23,7 @@ import {
   MetricDescriptorType,
 } from '../src';
 import * as types from '@opentelemetry/types';
-import { LabelSet } from '../src/types';
+import { LabelSet } from '../src/LabelSet';
 import {
   NoopLogger,
   NoopMetric,

From 88e598011b4adfab11dd699b64401374c8230f48 Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Mon, 4 Nov 2019 14:44:13 -0800
Subject: [PATCH 10/13] fix: update "encoded" to "identifier"

---
 packages/opentelemetry-metrics/src/LabelSet.ts     | 8 ++++----
 packages/opentelemetry-metrics/src/Meter.ts        | 6 +++---
 packages/opentelemetry-metrics/src/Metric.ts       | 8 ++++----
 packages/opentelemetry-metrics/test/Meter.test.ts  | 4 ++--
 packages/opentelemetry-types/src/metrics/Meter.ts  | 2 +-
 packages/opentelemetry-types/src/metrics/Metric.ts | 4 ++--
 6 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/packages/opentelemetry-metrics/src/LabelSet.ts b/packages/opentelemetry-metrics/src/LabelSet.ts
index 67d6aa7ab1..fb038384bf 100644
--- a/packages/opentelemetry-metrics/src/LabelSet.ts
+++ b/packages/opentelemetry-metrics/src/LabelSet.ts
@@ -17,14 +17,14 @@
 import * as types from '@opentelemetry/types';
 
 /**
- * Canonicalized labels with an unique string encoded.
+ * Canonicalized labels with an unique string identifier.
  */
 export class LabelSet implements types.LabelSet {
-  encoded: string;
+  identifier: string;
   labels: types.Labels;
 
-  constructor(encoded: string, labels: types.Labels) {
-    this.encoded = encoded;
+  constructor(identifier: string, labels: types.Labels) {
+    this.identifier = identifier;
     this.labels = labels;
   }
 }
diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index adbd9221d7..5f55205192 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -156,12 +156,12 @@ export class Meter implements types.Meter {
   /**
    * Provide a pre-computed re-useable LabelSet by
    * converting the unordered labels into a canonicalized
-   * set of lables with an unique encoded, useful for pre-aggregation.
+   * set of lables with an unique identifier, useful for pre-aggregation.
    * @param labels user provided unordered Labels.
    */
   labels(labels: types.Labels): types.LabelSet {
     let keys = Object.keys(labels).sort();
-    let encoded = keys.reduce((result, key) => {
+    let identifier = keys.reduce((result, key) => {
       if (result.length > 2) {
         result += ',';
       }
@@ -171,7 +171,7 @@ export class Meter implements types.Meter {
     keys.forEach(key => {
       sortedLabels[key] = labels[key];
     });
-    return new LabelSet(encoded, sortedLabels);
+    return new LabelSet(identifier, sortedLabels);
   }
 
   /**
diff --git a/packages/opentelemetry-metrics/src/Metric.ts b/packages/opentelemetry-metrics/src/Metric.ts
index a8e6caea5e..4c54313a5b 100644
--- a/packages/opentelemetry-metrics/src/Metric.ts
+++ b/packages/opentelemetry-metrics/src/Metric.ts
@@ -52,11 +52,11 @@ export abstract class Metric<T extends BaseHandle> implements types.Metric<T> {
    * @param labelSet the canonicalized LabelSet used to associate with this metric handle.
    */
   getHandle(labelSet: types.LabelSet): T {
-    if (this._handles.has(labelSet.encoded))
-      return this._handles.get(labelSet.encoded)!;
+    if (this._handles.has(labelSet.identifier))
+      return this._handles.get(labelSet.identifier)!;
 
     const handle = this._makeHandle(labelSet);
-    this._handles.set(labelSet.encoded, handle);
+    this._handles.set(labelSet.identifier, handle);
     return handle;
   }
 
@@ -74,7 +74,7 @@ export abstract class Metric<T extends BaseHandle> implements types.Metric<T> {
    * @param labelSet the canonicalized LabelSet used to associate with this metric handle.
    */
   removeHandle(labelSet: types.LabelSet): void {
-    this._handles.delete(labelSet.encoded);
+    this._handles.delete(labelSet.identifier);
   }
 
   /**
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index 231c697273..1f715ede13 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -54,8 +54,8 @@ describe('Meter', () => {
         [keya]: 'value1',
         [keyb]: 'value2',
       };
-      const encoded = '|#keya:value1,keyb:value2';
-      assert.deepEqual(labelSet, new LabelSet(encoded, orderedLabels));
+      const identifier = '|#keya:value1,keyb:value2';
+      assert.deepEqual(labelSet, new LabelSet(identifier, orderedLabels));
     });
   });
 
diff --git a/packages/opentelemetry-types/src/metrics/Meter.ts b/packages/opentelemetry-types/src/metrics/Meter.ts
index 5913f5e21a..f9edeaabdd 100644
--- a/packages/opentelemetry-types/src/metrics/Meter.ts
+++ b/packages/opentelemetry-types/src/metrics/Meter.ts
@@ -62,7 +62,7 @@ export interface Meter {
   /**
    * Provide a pre-computed re-useable LabelSet by
    * converting the unordered labels into a canonicalized
-   * set of lables with an unique encoded, useful for pre-aggregation.
+   * set of lables with an unique identifier, useful for pre-aggregation.
    * @param labels user provided unordered Labels.
    */
   labels(labels: Labels): LabelSet;
diff --git a/packages/opentelemetry-types/src/metrics/Metric.ts b/packages/opentelemetry-types/src/metrics/Metric.ts
index d86fda6cba..0c011d3811 100644
--- a/packages/opentelemetry-types/src/metrics/Metric.ts
+++ b/packages/opentelemetry-types/src/metrics/Metric.ts
@@ -105,9 +105,9 @@ export interface Metric<T> {
 export type Labels = Record<string, string>;
 
 /**
- * Canonicalized labels with an unique string encoded.
+ * Canonicalized labels with an unique string identifier.
  */
 export interface LabelSet {
-  encoded: string;
+  identifier: string;
   labels: Labels;
 }

From 167394e6973380c48d01c8f1c12f59d5adfa7ffb Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Wed, 6 Nov 2019 13:43:05 -0800
Subject: [PATCH 11/13] chore: update naming

---
 packages/opentelemetry-metrics/src/Handle.ts | 12 ++++++------
 packages/opentelemetry-metrics/src/Meter.ts  |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/packages/opentelemetry-metrics/src/Handle.ts b/packages/opentelemetry-metrics/src/Handle.ts
index f38eb2f869..14dd66addc 100644
--- a/packages/opentelemetry-metrics/src/Handle.ts
+++ b/packages/opentelemetry-metrics/src/Handle.ts
@@ -25,8 +25,8 @@ export class BaseHandle {
   protected _data = 0;
   protected _labelSet: types.LabelSet;
 
-  constructor(_labelSet: types.LabelSet) {
-    this._labelSet = _labelSet;
+  constructor(labelSet: types.LabelSet) {
+    this._labelSet = labelSet;
   }
 
   /**
@@ -51,13 +51,13 @@ export class BaseHandle {
  */
 export class CounterHandle extends BaseHandle implements types.CounterHandle {
   constructor(
-    _labelSet: types.LabelSet,
+    labelSet: types.LabelSet,
     private readonly _disabled: boolean,
     private readonly _monotonic: boolean,
     private readonly _valueType: types.ValueType,
     private readonly _logger: types.Logger
   ) {
-    super(_labelSet);
+    super(labelSet);
   }
 
   add(value: number): void {
@@ -89,13 +89,13 @@ export class CounterHandle extends BaseHandle implements types.CounterHandle {
  */
 export class GaugeHandle extends BaseHandle implements types.GaugeHandle {
   constructor(
-    _labelSet: types.LabelSet,
+    labelSet: types.LabelSet,
     private readonly _disabled: boolean,
     private readonly _monotonic: boolean,
     private readonly _valueType: types.ValueType,
     private readonly _logger: types.Logger
   ) {
-    super(_labelSet);
+    super(labelSet);
   }
 
   set(value: number): void {
diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index 5f55205192..b602445f11 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -167,7 +167,7 @@ export class Meter implements types.Meter {
       }
       return (result += key + ':' + labels[key]);
     }, '|#');
-    let sortedLabels = {} as types.Labels;
+    let sortedLabels: types.Labels = {};
     keys.forEach(key => {
       sortedLabels[key] = labels[key];
     });

From eca223683d6e44b4d25465edb7c7e72cf9eec89f Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Wed, 6 Nov 2019 17:09:52 -0800
Subject: [PATCH 12/13] fix: conflicts

---
 packages/opentelemetry-metrics/src/Utils.ts   | 24 +++++++++++++++++++
 .../opentelemetry-metrics/test/Meter.test.ts  |  8 +++----
 2 files changed, 28 insertions(+), 4 deletions(-)
 create mode 100644 packages/opentelemetry-metrics/src/Utils.ts

diff --git a/packages/opentelemetry-metrics/src/Utils.ts b/packages/opentelemetry-metrics/src/Utils.ts
new file mode 100644
index 0000000000..e2c8fba463
--- /dev/null
+++ b/packages/opentelemetry-metrics/src/Utils.ts
@@ -0,0 +1,24 @@
+/*!
+ * Copyright 2019, 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.
+ */
+
+/**
+ * Type guard to remove nulls from arrays
+ *
+ * @param value value to be checked for null equality
+ */
+export function notNull<T>(value: T | null): value is T {
+  return value !== null;
+}
diff --git a/packages/opentelemetry-metrics/test/Meter.test.ts b/packages/opentelemetry-metrics/test/Meter.test.ts
index 7c3eedec5f..06fd599abc 100644
--- a/packages/opentelemetry-metrics/test/Meter.test.ts
+++ b/packages/opentelemetry-metrics/test/Meter.test.ts
@@ -538,8 +538,8 @@ describe('Meter', () => {
 
       meter.addExporter(exporter);
       const gauge = meter.createGauge('name') as GaugeMetric;
-      const handle = gauge.getHandle(['value1', 'value2']);
-      handle.set(20);
+      const labelSet = meter.labels({ value: 'value1', value2: 'value2' });
+      gauge.getHandle(labelSet).set(20);
     });
 
     it('should export a counter when it is updated', done => {
@@ -560,8 +560,8 @@ describe('Meter', () => {
       });
 
       meter.addExporter(exporter);
-      const handle = counter.getHandle(['value1', 'value2']);
-      handle.add(20);
+      const labelSet = meter.labels({ value: 'value1', value2: 'value2' });
+      counter.getHandle(labelSet).add(20);
     });
   });
 });

From 58717cb58c725d95bbe0906726d4e002a30aabc7 Mon Sep 17 00:00:00 2001
From: xiao-lix <lixiao900921@gmail.com>
Date: Thu, 7 Nov 2019 09:49:31 -0800
Subject: [PATCH 13/13] chore: update let to const

---
 packages/opentelemetry-metrics/src/Meter.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index da167aebd5..d1cb29fce7 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -195,14 +195,14 @@ export class Meter implements types.Meter {
    * @param labels user provided unordered Labels.
    */
   labels(labels: types.Labels): types.LabelSet {
-    let keys = Object.keys(labels).sort();
-    let identifier = keys.reduce((result, key) => {
+    const keys = Object.keys(labels).sort();
+    const identifier = keys.reduce((result, key) => {
       if (result.length > 2) {
         result += ',';
       }
       return (result += key + ':' + labels[key]);
     }, '|#');
-    let sortedLabels: types.Labels = {};
+    const sortedLabels: types.Labels = {};
     keys.forEach(key => {
       sortedLabels[key] = labels[key];
     });