1 files changed, 105 insertions, 0 deletions
diff --git a/kamon-core/src/legacy-main/scala/kamon/metric/instrument/MinMaxCounter.scala b/kamon-core/src/legacy-main/scala/kamon/metric/instrument/MinMaxCounter.scala
new file mode 100644
index 00000000..76fc2c2a
--- /dev/null
+++ b/kamon-core/src/legacy-main/scala/kamon/metric/instrument/MinMaxCounter.scala
@@ -0,0 +1,105 @@
+package kamon.metric.instrument
+
+/*
+ * =========================================================================================
+ * Copyright © 2013-2014 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.
+ * =========================================================================================
+ */
+
+import java.lang.Math.abs
+import java.util.concurrent.atomic.AtomicReference
+import akka.actor.Cancellable
+import kamon.jsr166.LongMaxUpdater
+import kamon.metric.instrument.Histogram.DynamicRange
+import kamon.util.PaddedAtomicLong
+import scala.concurrent.duration.FiniteDuration
+
+trait MinMaxCounter extends Instrument {
+  override type SnapshotType = Histogram.Snapshot
+
+  def increment(): Unit
+  def increment(times: Long): Unit
+  def decrement(): Unit
+  def decrement(times: Long): Unit
+  def refreshValues(): Unit
+}
+
+object MinMaxCounter {
+
+  def apply(dynamicRange: DynamicRange, refreshInterval: FiniteDuration, scheduler: RefreshScheduler): MinMaxCounter = {
+    val underlyingHistogram = Histogram(dynamicRange)
+    val minMaxCounter = new PaddedMinMaxCounter(underlyingHistogram)
+    val refreshValuesSchedule = scheduler.schedule(refreshInterval, () ⇒ {
+      minMaxCounter.refreshValues()
+    })
+
+    minMaxCounter.refreshValuesSchedule.set(refreshValuesSchedule)
+    minMaxCounter
+  }
+
+  def create(dynamicRange: DynamicRange, refreshInterval: FiniteDuration, scheduler: RefreshScheduler): MinMaxCounter =
+    apply(dynamicRange, refreshInterval, scheduler)
+
+}
+
+class PaddedMinMaxCounter(underlyingHistogram: Histogram) extends MinMaxCounter {
+  private val min = new LongMaxUpdater(0L)
+  private val max = new LongMaxUpdater(0L)
+  private val sum = new PaddedAtomicLong
+  val refreshValuesSchedule = new AtomicReference[Cancellable]()
+
+  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 collect(context: CollectionContext): Histogram.Snapshot = {
+    refreshValues()
+    underlyingHistogram.collect(context)
+  }
+
+  def cleanup: Unit = {
+    if (refreshValuesSchedule.get() != null)
+      refreshValuesSchedule.get().cancel()
+  }
+
+  def refreshValues(): 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)
+  }
+}