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Serialize min/max values from OTel histograms #11034

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Merged
gh-worker-dd-mergequeue-cf854d merged 1 commit into from
Apr 2, 2026
Merged

Serialize min/max values from OTel histograms #11034

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6 changes: 5 additions & 1 deletion ...ootstrap/src/main/java/datadog/trace/bootstrap/otel/metrics/data/OtelHistogramSketch.java
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Original file line number Diff line number Diff line change
Expand Up @@ -29,16 +29,20 @@ OtlpDataPoint doCollect(boolean reset) {
List<Double> binBoundaries;
List<Double> binCounts;
double sum;
double min;
double max;
synchronized (histogram) {
count = histogram.getCount();
binBoundaries = histogram.getBinBoundaries();
binCounts = histogram.getBinCounts();
sum = histogram.getSum();
min = histogram.getMinValue();
max = histogram.getMaxValue();
if (reset) {
histogram.clear();
}
}
return new OtlpHistogramPoint(count, binBoundaries, binCounts, sum);
return new OtlpHistogramPoint(count, binBoundaries, binCounts, sum, min, max);
}

/** Truncate IEEE-754 floating-point value to 10 bits precision. */
Expand Down
11 changes: 10 additions & 1 deletion ...bootstrap/src/main/java/datadog/trace/bootstrap/otel/metrics/data/OtlpHistogramPoint.java
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Expand Up @@ -7,12 +7,21 @@ public final class OtlpHistogramPoint extends OtlpDataPoint {
public final List<Double> bucketBoundaries;
public final List<Double> bucketCounts;
public final double sum;
public final double min;
public final double max;

OtlpHistogramPoint(
double count, List<Double> bucketBoundaries, List<Double> bucketCounts, double sum) {
double count,
List<Double> bucketBoundaries,
List<Double> bucketCounts,
double sum,
double min,
double max) {
this.count = count;
this.bucketBoundaries = bucketBoundaries;
this.bucketCounts = bucketCounts;
this.sum = sum;
this.min = min;
this.max = max;
}
}
4 changes: 4 additions & 0 deletions ...bootstrap/src/main/java/datadog/trace/bootstrap/otel/metrics/export/OtlpMetricsProto.java
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Expand Up @@ -117,6 +117,10 @@ public static byte[] recordDataPointMessage(GrowableBuffer buf, OtlpDataPoint po
writeI64(buf, (long) histogram.count);
writeTag(buf, 5, I64_WIRE_TYPE);
writeI64(buf, histogram.sum);
writeTag(buf, 11, I64_WIRE_TYPE);
writeI64(buf, histogram.min);
writeTag(buf, 12, I64_WIRE_TYPE);
writeI64(buf, histogram.max);
for (double bucketCount : histogram.bucketCounts) {
writeTag(buf, 6, I64_WIRE_TYPE);
writeI64(buf, (long) bucketCount);
Expand Down
9 changes: 7 additions & 2 deletions ...tel-bootstrap/src/test/java/datadog/trace/bootstrap/otel/metrics/data/OtlpTestPoints.java
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Expand Up @@ -15,7 +15,12 @@ public static OtlpDoublePoint doublePoint(double value) {
}

public static OtlpHistogramPoint histogramPoint(
double count, List<Double> bucketBoundaries, List<Double> bucketCounts, double sum) {
return new OtlpHistogramPoint(count, bucketBoundaries, bucketCounts, sum);
double count,
List<Double> bucketBoundaries,
List<Double> bucketCounts,
double sum,
double min,
double max) {
return new OtlpHistogramPoint(count, bucketBoundaries, bucketCounts, sum, min, max);
}
}
54 changes: 46 additions & 8 deletions ...strap/src/test/java/datadog/trace/bootstrap/otel/metrics/export/OtlpMetricsProtoTest.java
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Expand Up @@ -57,7 +57,8 @@
* double as_double = 4; sfixed64 as_int = 6; KeyValue attributes = 7; }
* HistogramDataPoint { fixed64 start_time_unix_nano = 2; fixed64 time_unix_nano = 3;
* fixed64 count = 4; double sum = 5; fixed64 bucket_counts = 6;
* double explicit_bounds = 7; KeyValue attributes = 9; }
* double explicit_bounds = 7; KeyValue attributes = 9;
* double min = 11; double max = 12; }
* </pre>
*/
class OtlpMetricsProtoTest {
Expand Down Expand Up @@ -242,14 +243,16 @@ private static MetricSpec histogram(
List<Double> bounds,
List<Double> counts,
double sum,
double min,
double max,
AttrSpec... attrs) {
return new MetricSpec(
name,
null,
null,
OtelInstrumentType.HISTOGRAM,
false,
histogramPoint(count, bounds, counts, sum),
histogramPoint(count, bounds, counts, sum, min, max),
asList(attrs));
}

Expand Down Expand Up @@ -358,20 +361,32 @@ static Stream<Arguments> cases() {
Arguments.of(
"histogram no buckets",
asList(
scope("io.hist", histogram("response.time", 1.0, emptyList(), asList(1.0), 0.5)))),
scope(
"io.hist",
histogram("response.time", 1.0, emptyList(), asList(1.0), 0.5, 0.5, 0.5)))),

// ── histogram — zero count and sum ────────────────────────────────────
Arguments.of(
"histogram zero count and sum",
asList(scope("io.hist", histogram("idle.time", 0.0, emptyList(), asList(0.0), 0.0)))),
asList(
scope(
"io.hist",
histogram("idle.time", 0.0, emptyList(), asList(0.0), 0.0, 0.0, 0.0)))),

// ── histogram — single explicit bound ─────────────────────────────────
Arguments.of(
"histogram single bound",
asList(
scope(
"io.hist",
histogram("request.size", 5.0, asList(100.0), asList(4.0, 1.0), 280.0)))),
histogram(
"request.size",
5.0,
asList(100.0),
asList(4.0, 1.0),
280.0,
20.0,
200.0)))),

// ── histogram — with explicit bounds and attrs ────────────────────────
Arguments.of(
Expand All @@ -385,6 +400,8 @@ static Stream<Arguments> cases() {
asList(1.0, 5.0, 10.0),
asList(2.0, 3.0, 4.0, 1.0),
45.5,
0.5,
12.0,
strAttr("region", "us-east"))))),

// ── histogram — many buckets with multiple attrs ───────────────────────
Expand All @@ -399,6 +416,8 @@ static Stream<Arguments> cases() {
asList(1.0, 2.0, 5.0, 10.0, 25.0, 50.0, 100.0),
asList(5.0, 10.0, 20.0, 30.0, 15.0, 12.0, 6.0, 2.0),
4321.0,
0.5,
150.0,
longAttr("shard", 3L),
boolAttr("cached", false))))),

Expand Down Expand Up @@ -886,12 +905,13 @@ private static void verifyNumberDataPoint(
}

/**
* Parses a {@code HistogramDataPoint} message body and asserts timestamps, count, sum, bucket
* counts, explicit bounds, and attributes.
* Parses a {@code HistogramDataPoint} message body and asserts timestamps, count, sum, min, max,
* bucket counts, explicit bounds, and attributes.
*
* <pre>
* HistogramDataPoint { start_time_unix_nano=2, time_unix_nano=3, count=4,
* sum=5, bucket_counts=6, explicit_bounds=7, attributes=9 }
* sum=5, bucket_counts=6, explicit_bounds=7, attributes=9,
* min=11, max=12 }
* </pre>
*/
private static void verifyHistogramDataPoint(CodedInputStream dp, MetricSpec expected)
Expand All @@ -901,6 +921,8 @@ private static void verifyHistogramDataPoint(CodedInputStream dp, MetricSpec exp
boolean foundEndTime = false;
boolean foundCount = false;
boolean foundSum = false;
boolean foundMin = false;
boolean foundMax = false;
List<Long> parsedBucketCounts = new ArrayList<>();
List<Double> parsedBounds = new ArrayList<>();
List<String> parsedAttrKeys = new ArrayList<>();
Expand Down Expand Up @@ -937,6 +959,20 @@ private static void verifyHistogramDataPoint(CodedInputStream dp, MetricSpec exp
case 9: // attributes (repeated KeyValue)
parsedAttrKeys.add(readKeyValueKey(dp.readBytes().newCodedInput()));
break;
case 11: // min (double via fixed64)
assertEquals(
Double.doubleToRawLongBits(hp.min),
Double.doubleToRawLongBits(dp.readDouble()),
"histogram min");
foundMin = true;
break;
case 12: // max (double via fixed64)
assertEquals(
Double.doubleToRawLongBits(hp.max),
Double.doubleToRawLongBits(dp.readDouble()),
"histogram max");
foundMax = true;
break;
default:
dp.skipField(tag);
}
Expand All @@ -946,6 +982,8 @@ private static void verifyHistogramDataPoint(CodedInputStream dp, MetricSpec exp
assertTrue(foundEndTime, "time_unix_nano required for histogram " + expected.name);
assertTrue(foundCount, "count required for histogram " + expected.name);
assertTrue(foundSum, "sum required for histogram " + expected.name);
assertTrue(foundMin, "min required for histogram " + expected.name);
assertTrue(foundMax, "max required for histogram " + expected.name);

assertEquals(
hp.bucketCounts.size(),
Expand Down
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