max, min and merge operations for MetricSnapshot

1 files changed, 112 insertions, 0 deletions

diff --git a/kamon-core/src/main/scala/kamon/metrics/Metrics.scala b/kamon-core/src/main/scala/kamon/metrics/Metrics.scala
new file mode 100644
index 00000000..61f79a29
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metrics/Metrics.scala
@@ -0,0 +1,112 @@
+/*
+ * =========================================================================================
+ * Copyright © 2013 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.metrics
+
+import annotation.tailrec
+import com.typesafe.config.Config
+import kamon.metrics.MetricSnapshot.Measurement
+
+case class MetricGroupIdentity(name: String, category: MetricGroupIdentity.Category)
+
+trait MetricIdentity {
+  def name: String
+}
+
+trait MetricGroupRecorder {
+  def record(identity: MetricIdentity, value: Long)
+  def collect: MetricGroupSnapshot
+}
+
+trait MetricGroupSnapshot {
+  def metrics: Map[MetricIdentity, MetricSnapshot]
+}
+
+trait MetricRecorder {
+  def record(value: Long)
+  def collect(): MetricSnapshot
+}
+
+trait MetricSnapshot {
+  def numberOfMeasurements: Long
+  def measurementLevels: Vector[Measurement]
+
+  def max: Long = measurementLevels.lastOption.map(_.value).getOrElse(0)
+  def min: Long = measurementLevels.headOption.map(_.value).getOrElse(0)
+
+  def merge(that: MetricSnapshot): MetricSnapshot = {
+    val mergedMeasurements = Vector.newBuilder[Measurement]
+
+    @tailrec def go(left: Vector[Measurement], right: Vector[Measurement], totalNrOfMeasurements: Long): Long = {
+      if (left.nonEmpty && right.nonEmpty) {
+        val leftValue = left.head
+        val rightValue = right.head
+
+        if (rightValue.value == leftValue.value) {
+          val merged = rightValue.merge(leftValue)
+          mergedMeasurements += merged
+          go(left.tail, right.tail, totalNrOfMeasurements + merged.count)
+        } else {
+          if (leftValue.value < rightValue.value) {
+            mergedMeasurements += leftValue
+            go(left.tail, right, totalNrOfMeasurements + leftValue.count)
+          } else {
+            mergedMeasurements += rightValue
+            go(left, right.tail, totalNrOfMeasurements + rightValue.count)
+          }
+        }
+      } else {
+        if (left.isEmpty && right.nonEmpty) {
+          mergedMeasurements += right.head
+          go(left, right.tail, totalNrOfMeasurements + right.head.count)
+        } else {
+          if (left.nonEmpty && right.isEmpty) {
+            mergedMeasurements += left.head
+            go(left.tail, right, totalNrOfMeasurements + left.head.count)
+          } else totalNrOfMeasurements
+        }
+      }
+    }
+
+    val totalNrOfMeasurements = go(measurementLevels, that.measurementLevels, 0)
+    DefaultMetricSnapshot(totalNrOfMeasurements, mergedMeasurements.result())
+  }
+}
+
+object MetricSnapshot {
+  case class Measurement(value: Long, count: Long) {
+    def merge(that: Measurement) = Measurement(value, count + that.count)
+  }
+}
+
+case class DefaultMetricSnapshot(numberOfMeasurements: Long, measurementLevels: Vector[MetricSnapshot.Measurement]) extends MetricSnapshot
+
+object MetricGroupIdentity {
+  trait Category {
+    def name: String
+  }
+
+  val AnyCategory = new Category {
+    def name: String = "match-all"
+    override def equals(that: Any): Boolean = that.isInstanceOf[Category]
+  }
+}
+
+trait MetricGroupFactory {
+  type Group <: MetricGroupRecorder
+  def create(config: Config): Group
+}
+