implement HdrHistogram and Distribution snapshots

1 files changed, 40 insertions, 0 deletions

diff --git a/kamon-core/src/main/scala/kamon/metric/instrument/HistogramExtension.scala b/kamon-core/src/main/scala/kamon/metric/instrument/HistogramExtension.scala
new file mode 100644
index 00000000..ebb82040
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metric/instrument/HistogramExtension.scala
@@ -0,0 +1,40 @@
+package org.HdrHistogram
+
+import java.nio.ByteBuffer
+import java.util.concurrent.atomic.AtomicLongArray
+
+import kamon.metric.instrument.DynamicRange
+
+/**
+  * This class exposes package-private members of the [[AtomicHistogram]] class that are required to properly generate
+  * snapshots of our HdrHistogram implementation.
+  */
+abstract class AtomicHistogramExtension(dr: DynamicRange)
+    extends AtomicHistogram(dr.lowestDiscernibleValue, dr.highestTrackableValue, dr.significantValueDigits) {
+
+  override def incrementTotalCount(): Unit = {}
+  override def addToTotalCount(value: Long): Unit = {}
+
+  def countsArray(): AtomicLongArray = counts
+  def protectedUnitMagnitude(): Int = unitMagnitude
+  def protectedSubBucketHalfCount(): Int = subBucketHalfCount
+  def protectedSubBucketHalfCountMagnitude(): Int = subBucketHalfCountMagnitude
+}
+
+/**
+  * Exposes the package-private members of [[ZigZagEncoding]].
+  */
+object ZigZag {
+  def putLong(buffer: ByteBuffer, value: Long): Unit =
+    ZigZagEncoding.putLong(buffer, value)
+
+  def getLong(buffer: ByteBuffer): Long =
+    ZigZagEncoding.getLong(buffer)
+
+  def putInt(buffer: ByteBuffer, value: Int): Unit =
+    ZigZagEncoding.putInt(buffer, value)
+
+  def getInt(buffer: ByteBuffer): Int =
+    ZigZagEncoding.getInt(buffer)
+}
+