1 files changed, 88 insertions, 0 deletions
diff --git a/kamon-core/src/main/scala/kamon/metric/RangeSampler.scala b/kamon-core/src/main/scala/kamon/metric/RangeSampler.scala
new file mode 100644
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--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metric/RangeSampler.scala
@@ -0,0 +1,88 @@
+/* =========================================================================================
+ * Copyright © 2013-2017 the kamon project <http://kamon.io/>
+ *
+ * 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
+ *
+ *   http://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.
+ * =========================================================================================
+ */
+
+package kamon.metric
+
+import java.lang.Math.abs
+import java.time.Duration
+import java.util.concurrent.atomic.AtomicLong
+
+trait RangeSampler {
+  def unit: MeasurementUnit
+  def dynamicRange: DynamicRange
+  def sampleInterval: Duration
+
+  def increment(): Unit
+  def increment(times: Long): Unit
+  def decrement(): Unit
+  def decrement(times: Long): Unit
+  def sample(): Unit
+}
+
+class SimpleRangeSampler(name: String, tags: Map[String, String], underlyingHistogram: AtomicHdrHistogram,
+    val sampleInterval: Duration) extends RangeSampler {
+
+  private val min = AtomicLongMaxUpdater()
+  private val max = AtomicLongMaxUpdater()
+  private val sum = new AtomicLong()
+
+  def dynamicRange: DynamicRange =
+    underlyingHistogram.dynamicRange
+
+  def unit: MeasurementUnit =
+    underlyingHistogram.unit
+
+  def increment(): Unit =
+    increment(1L)
+
+  def increment(times: Long): Unit = {
+    val currentValue = sum.addAndGet(times)
+    max.update(currentValue)
+  }
+
+  def decrement(): Unit =
+    decrement(1L)
+
+  def decrement(times: Long): Unit = {
+    val currentValue = sum.addAndGet(-times)
+    min.update(-currentValue)
+  }
+
+  def sample(): Unit = {
+    val currentValue = {
+      val value = sum.get()
+      if (value <= 0) 0 else value
+    }
+
+    val currentMin = {
+      val rawMin = min.maxThenReset(-currentValue)
+      if (rawMin >= 0)
+        0
+      else
+        abs(rawMin)
+    }
+
+    val currentMax = max.maxThenReset(currentValue)
+
+    underlyingHistogram.record(currentValue)
+    underlyingHistogram.record(currentMin)
+    underlyingHistogram.record(currentMax)
+  }
+
+  private[kamon] def snapshot(resetState: Boolean = true): MetricDistribution = {
+    sample()
+    underlyingHistogram.snapshot(resetState)
+  }
+}