From d0d9abbe516bfbe2e0fc878ece25b96b5c6e5caa Mon Sep 17 00:00:00 2001
From: Jack Berg <jberg@newrelic.com>
Date: Tue, 14 Feb 2023 15:54:11 -0600
Subject: [PATCH] Stop ignoring long measurements in HistogramExemplarReservoir

---
 .../exemplar/HistogramExemplarReservoir.java  |  5 +++
 .../HistogramExemplarReservoirTest.java       | 33 +++++++++++++++++--
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoir.java b/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoir.java
index f86d67fbec8..ac06e64058e 100644
--- a/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoir.java
+++ b/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoir.java
@@ -23,6 +23,11 @@ class HistogramExemplarReservoir extends FixedSizeExemplarReservoir<DoubleExempl
         ReservoirCell::getAndResetDouble);
   }
 
+  @Override
+  public void offerLongMeasurement(long value, Attributes attributes, Context context) {
+    super.offerDoubleMeasurement((double) value, attributes, context);
+  }
+
   static class HistogramCellSelector implements ReservoirCellSelector {
 
     private final double[] boundaries;
diff --git a/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoirTest.java b/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoirTest.java
index 1d5964ea01b..a6882dfe797 100644
--- a/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoirTest.java
+++ b/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/internal/exemplar/HistogramExemplarReservoirTest.java
@@ -19,7 +19,7 @@
 
 class HistogramExemplarReservoirTest {
   @Test
-  public void noMeasurement_returnsEmpty() {
+  void noMeasurement_returnsEmpty() {
     TestClock clock = TestClock.create();
     ExemplarReservoir<DoubleExemplarData> reservoir =
         new HistogramExemplarReservoir(clock, Collections.emptyList());
@@ -27,7 +27,7 @@ public void noMeasurement_returnsEmpty() {
   }
 
   @Test
-  public void oneBucket_samplesEverything() {
+  void oneBucket_samplesEverything() {
     TestClock clock = TestClock.create();
     ExemplarReservoir<DoubleExemplarData> reservoir =
         new HistogramExemplarReservoir(clock, Collections.emptyList());
@@ -66,7 +66,7 @@ public void oneBucket_samplesEverything() {
   }
 
   @Test
-  public void multipleBuckets_samplesIntoCorrectBucket() {
+  void multipleBuckets_samplesIntoCorrectBucket() {
     TestClock clock = TestClock.create();
     AttributeKey<Long> bucketKey = AttributeKey.longKey("bucket");
     ExemplarReservoir<DoubleExemplarData> reservoir =
@@ -95,4 +95,31 @@ public void multipleBuckets_samplesIntoCorrectBucket() {
               assertThat(e.getFilteredAttributes()).isEqualTo(Attributes.of(bucketKey, 3L));
             });
   }
+
+  @Test
+  void longMeasurement_CastsToDouble() {
+    TestClock clock = TestClock.create();
+    ExemplarReservoir<DoubleExemplarData> reservoir =
+        new HistogramExemplarReservoir(clock, Collections.emptyList());
+    reservoir.offerLongMeasurement(1L, Attributes.empty(), Context.root());
+    assertThat(reservoir.collectAndReset(Attributes.empty()))
+        .hasSize(1)
+        .satisfiesExactly(
+            exemplar -> {
+              assertThat(exemplar.getEpochNanos()).isEqualTo(clock.now());
+              assertThat(exemplar.getValue()).isEqualTo(1);
+              assertThat(exemplar.getFilteredAttributes()).isEmpty();
+            });
+    // Measurement count is reset, we should sample a new measurement (and only one)
+    clock.advance(Duration.ofSeconds(1));
+    reservoir.offerLongMeasurement(2, Attributes.empty(), Context.root());
+    assertThat(reservoir.collectAndReset(Attributes.empty()))
+        .hasSize(1)
+        .satisfiesExactly(
+            exemplar -> {
+              assertThat(exemplar.getEpochNanos()).isEqualTo(clock.now());
+              assertThat(exemplar.getValue()).isEqualTo(2);
+              assertThat(exemplar.getFilteredAttributes()).isEmpty();
+            });
+  }
 }