fix(sdk-metrics): ignore NaN value recordings for histograms

CHANGELOG.md

@@ -15,8 +15,9 @@ For experimental package changes, see the [experimental CHANGELOG](experimental/
 
 ### :bug: (Bug Fix)
 
-* fix(sdk-metrics): handle zero bucket counts in exponential histogram merge
-[#4459](https://github.com/open-telemetry/opentelemetry-js/pull/4459) @mwear
+* fix(sdk-metrics): handle zero bucket counts in exponential histogram merge [#4459](https://github.com/open-telemetry/opentelemetry-js/pull/4459) @mwear
+* fix(sdk-metrics): ignore `NaN` value recordings in Histograms [#4455](https://github.com/open-telemetry/opentelemetry-js/pull/4455) @pichlermarc
+  * fixes a bug where recording `NaN` on a histogram would result in the sum of bucket count values not matching the overall count
 
 ### :books: (Refine Doc)
 

experimental/packages/opentelemetry-exporter-prometheus/test/PrometheusSerializer.test.ts

@@ -622,7 +622,6 @@ describe('PrometheusSerializer', () => {
     it('should serialize non-finite values', async () => {
       const serializer = new PrometheusSerializer();
       const cases = [
-        [NaN, 'NaN'],
         [-Infinity, '-Inf'],
         [+Infinity, '+Inf'],
       ] as [number, string][];

packages/sdk-metrics/src/aggregator/ExponentialHistogram.ts

@@ -193,6 +193,12 @@ export class ExponentialHistogramAccumulation implements Accumulation {
    * @param increment
    */
   updateByIncrement(value: number, increment: number) {
+    // NaN does not fall into any bucket, is not zero and should not be counted,
+    // NaN is never greater than max nor less than min, therefore return as there's nothing for us to do.
+    if (Number.isNaN(value)) {
+      return;
+    }
+
     if (value > this._max) {
       this._max = value;
     }

packages/sdk-metrics/src/aggregator/Histogram.ts

@@ -72,6 +72,12 @@ export class HistogramAccumulation implements Accumulation {
   ) {}
 
   record(value: number): void {
+    // NaN does not fall into any bucket, is not zero and should not be counted,
+    // NaN is never greater than max nor less than min, therefore return as there's nothing for us to do.
+    if (Number.isNaN(value)) {
+      return;
+    }
+
     this._current.count += 1;
     this._current.sum += value;
 

packages/sdk-metrics/test/Instruments.test.ts

@@ -247,6 +247,7 @@ describe('Instruments', () => {
       upDownCounter.add(1.1, { foo: 'bar' });
       // non-number values should be ignored.
       upDownCounter.add('1' as any);
+
       await validateExport(deltaReader, {
         dataPointType: DataPointType.SUM,
         isMonotonic: false,
@@ -506,6 +507,7 @@ describe('Instruments', () => {
       histogram.record(0.1, { foo: 'bar' });
       // non-number values should be ignored.
       histogram.record('1' as any);
+      histogram.record(NaN);
 
       await validateExport(deltaReader, {
         dataPointType: DataPointType.HISTOGRAM,

packages/sdk-metrics/test/aggregator/ExponentialHistogram.test.ts

@@ -215,6 +215,20 @@ describe('ExponentialHistogramAccumulation', () => {
         }
       });
     });
+
+    it('ignores NaN', () => {
+      const accumulation = new ExponentialHistogramAccumulation([0, 0], 1);
+
+      accumulation.record(NaN);
+
+      assert.strictEqual(accumulation.scale, 0);
+      assert.strictEqual(accumulation.max, -Infinity);
+      assert.strictEqual(accumulation.min, Infinity);
+      assert.strictEqual(accumulation.sum, 0);
+      assert.strictEqual(accumulation.count, 0);
+      assert.deepStrictEqual(getCounts(accumulation.positive), []);
+      assert.deepStrictEqual(getCounts(accumulation.negative), []);
+    });
   });
   describe('merge', () => {
     it('handles simple (even) case', () => {

packages/sdk-metrics/test/aggregator/Histogram.test.ts

@@ -257,6 +257,19 @@ describe('HistogramAccumulation', () => {
         accumulation.record(value);
       }
     });
+
+    it('ignores NaN', () => {
+      const accumulation = new HistogramAccumulation([0, 0], [1, 10, 100]);
+
+      accumulation.record(NaN);
+
+      const pointValue = accumulation.toPointValue();
+      assert.strictEqual(pointValue.max, -Infinity);
+      assert.strictEqual(pointValue.min, Infinity);
+      assert.strictEqual(pointValue.sum, 0);
+      assert.strictEqual(pointValue.count, 0);
+      assert.deepStrictEqual(pointValue.buckets.counts, [0, 0, 0, 0]);
+    });
   });
 
   describe('setStartTime', () => {

packages/sdk-metrics/test/regression/histogram-recording-nan.test.ts

@@ -0,0 +1,99 @@
+/*
+ * Copyright The 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.
+ */
+
+import * as assert from 'assert';
+import {
+  Aggregation,
+  AggregationTemporality,
+  MeterProvider,
+  MetricReader,
+  DataPoint,
+  ExponentialHistogram,
+  Histogram,
+} from '../../src';
+import { TestMetricReader } from '../export/TestMetricReader';
+
+describe('histogram-recording-nan', () => {
+  it('exponential histogram should not count NaN', async () => {
+    const reader = new TestMetricReader({
+      aggregationTemporalitySelector() {
+        return AggregationTemporality.CUMULATIVE;
+      },
+      aggregationSelector(type) {
+        return Aggregation.ExponentialHistogram();
+      },
+    });
+    const meterProvider = new MeterProvider({
+      readers: [reader],
+    });
+
+    const meter = meterProvider.getMeter('my-meter');
+    const hist = meter.createHistogram('testhist');
+
+    hist.record(1);
+    hist.record(2);
+    hist.record(4);
+    hist.record(NaN);
+
+    const resourceMetrics1 = await collectNoErrors(reader);
+    const dataPoint1 = resourceMetrics1.scopeMetrics[0].metrics[0]
+      .dataPoints[0] as DataPoint<ExponentialHistogram>;
+
+    assert.deepStrictEqual(
+      dataPoint1.value.count,
+      3,
+      'Sum of bucket count values should match overall count'
+    );
+  });
+
+  it('explicit bucket histogram should not count NaN', async () => {
+    const reader = new TestMetricReader({
+      aggregationTemporalitySelector() {
+        return AggregationTemporality.CUMULATIVE;
+      },
+      aggregationSelector(type) {
+        return Aggregation.Histogram();
+      },
+    });
+    const meterProvider = new MeterProvider({
+      readers: [reader],
+    });
+
+    const meter = meterProvider.getMeter('my-meter');
+    const hist = meter.createHistogram('testhist');
+
+    hist.record(1);
+    hist.record(2);
+    hist.record(4);
+    hist.record(NaN);
+
+    const resourceMetrics1 = await collectNoErrors(reader);
+    const dataPoint1 = resourceMetrics1.scopeMetrics[0].metrics[0]
+      .dataPoints[0] as DataPoint<Histogram>;
+
+    assert.deepStrictEqual(
+      dataPoint1.value.count,
+      3,
+      'Sum of bucket count values should match overall count'
+    );
+  });
+
+  const collectNoErrors = async (reader: MetricReader) => {
+    const { resourceMetrics, errors } = await reader.collect();
+    assert.strictEqual(errors.length, 0);
+    return resourceMetrics;
+  };
+});