disallow duplicate dimensions sets

Closes #20

Author: jaredcnance

src/logger/MetricsContext.ts

@@ -88,8 +88,34 @@ export class MetricsContext {
    *
    * @param dimensions
    */
-  public putDimensions(dimensions: Record<string, string>): void {
-    this.dimensions.push(dimensions);
+  public putDimensions(incomingDimensionSet: Record<string, string>): void {
+    if (this.dimensions.length === 0) {
+      this.dimensions.push(incomingDimensionSet);
+      return;
+    }
+
+    for (let i = 0; i < this.dimensions.length; i++) {
+      const existingDimensionSet = this.dimensions[i];
+
+      // check for duplicate dimensions when putting
+      // this is an O(n^2) operation, but since we never expect to have more than
+      // 10 dimensions, this is acceptable for almost all cases. 
+      // This makes re-using loggers much easier.
+      const existingDimensionSetKeys = Object.keys(existingDimensionSet);
+      const incomingDimensionSetKeys = Object.keys(incomingDimensionSet);
+      if (existingDimensionSetKeys.length !== incomingDimensionSetKeys.length) {
+        this.dimensions.push(incomingDimensionSet);
+        return;
+      }
+
+      for (let j = 0; j < existingDimensionSetKeys.length; j++) {
+        if (!incomingDimensionSetKeys.includes(existingDimensionSetKeys[j])) {
+          // we're done now because we know that the dimensions keys are not identical
+          this.dimensions.push(incomingDimensionSet);
+          return;
+        }
+      }
+    }
   }
 
   /**

src/logger/__tests__/MetricsContext.test.ts

@@ -29,6 +29,53 @@ test('putDimension adds key to dimension and sets the dimension as a property',
   expect(context.getDimensions()[0]).toStrictEqual(expectedDimension);
 });
 
+test('putDimension will not duplicate dimensions', () => {
+  // arrange
+  const context = MetricsContext.empty();
+  const dimension = faker.random.word();
+  const expectedDimension = { dimension };
+
+  // act
+  context.putDimensions({ dimension });
+  context.putDimensions({ dimension });
+
+  // assert
+  expect(context.getDimensions().length).toBe(1);
+  expect(context.getDimensions()[0]).toStrictEqual(expectedDimension);
+});
+
+test('putDimension will not duplicate dimensions, multiple in different order', () => {
+  // arrange
+  const context = MetricsContext.empty();
+  const dimension1 = faker.random.word();
+  const dimension2 = faker.random.word();
+  const expectedDimension = { dimension1, dimension2 };
+
+  // act
+  context.putDimensions({ dimension1, dimension2 });
+  context.putDimensions({ dimension2, dimension1 });
+
+  // assert
+  expect(context.getDimensions().length).toBe(1);
+  expect(context.getDimensions()[0]).toStrictEqual(expectedDimension);
+});
+
+test('putDimension accepts multiple unique dimension sets', () => {
+  // arrange
+  const context = MetricsContext.empty();
+  const expectedDimension1 = { d1: faker.random.word(), d2: faker.random.word() };
+  const expectedDimension2 = { d2: faker.random.word(), d3: faker.random.word() };
+
+  // act
+  context.putDimensions(expectedDimension1);
+  context.putDimensions(expectedDimension2);
+
+  // assert
+  expect(context.getDimensions().length).toBe(2);
+  expect(context.getDimensions()[0]).toStrictEqual(expectedDimension1);
+  expect(context.getDimensions()[1]).toStrictEqual(expectedDimension2);
+});
+
 test('getDimensions returns default dimensions if custom dimensions not set', () => {
   // arrange
   const context = MetricsContext.empty();

test/integ/agent/end-to-end.integ.ts

@@ -90,16 +90,17 @@ test(
 
     Configuration.agentEndpoint = 'tcp://0.0.0.0:25888';
 
-    const doWork = metricScope(metrics => () => {
-      metrics.putDimensions(dimensions);
-      metrics.putMetric(metricName, 100, 'Milliseconds');
-      metrics.setProperty('RequestId', '422b1569-16f6-4a03-b8f0-fe3fd9b100f8');
-    });
-
-    // act
-    doWork();
-    await Sleep(idleTimeout);
-    doWork();
+const doWork = metricScope(metrics => () => {
+  metrics.putDimensions(dimensions);
+  metrics.putMetric(metricName, 100, 'Milliseconds');
+  metrics.setProperty('RequestId', '422b1569-16f6-4a03-b8f0-fe3fd9b100f8');
+});
+
+// act
+doWork();
+doWork();
+await Sleep(idleTimeout);
+doWork();
 
     // assert
     await waitForMetricExistence(metricName, expectedSamples);