return the same percentile rank that was requested on Distribution.pe…

…rcentile(...), fixes #772
kamon-io · Jun 3, 2020 · 103f5c7 · 103f5c7
1 parent 1cbdc61
commit 103f5c7
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diff --git a/core/kamon-core-tests/src/test/scala/kamon/metric/HistogramSpec.scala b/core/kamon-core-tests/src/test/scala/kamon/metric/HistogramSpec.scala
@@ -74,6 +74,16 @@ class HistogramSpec extends WordSpec with Matchers with InstrumentInspection.Syn
       )
     }
 
+    "return the same percentile value that was request on a resulting distribution" in {
+      val histogram = Kamon.histogram("returned-percentile").withoutTags()
+      (1L to 10L).foreach(histogram.record)
+
+      val distribution = histogram.distribution()
+      distribution.percentile(99).rank shouldBe(99)
+      distribution.percentile(99.9).rank shouldBe(99.9)
+      distribution.percentile(99.99).rank shouldBe(99.99D)
+    }
+
     "[private api] record values and optionally keep the internal state when a snapshot is taken" in {
       val histogram = Kamon.histogram("test", unit = time.nanoseconds).withoutTags()
       histogram.record(100)

diff --git a/core/kamon-core/src/main/scala/kamon/metric/Distribution.scala b/core/kamon-core/src/main/scala/kamon/metric/Distribution.scala
@@ -285,7 +285,7 @@ object Distribution {
           currentPercentile = percentiles.next()
         }
 
-        currentPercentile
+        immutable.Percentile(p, currentPercentile.value, currentPercentile.countAtRank)
 
       } else immutable.Percentile(p, 0, 0)
     }