From b6ea0a93e6be8e1f355f1bc993618d178d0c9372 Mon Sep 17 00:00:00 2001
From: Ivan Topolnak <itopolnak@despegar.com>
Date: Mon, 27 Jan 2014 19:09:40 -0300
Subject: first implementation of a universal metrics repository for any kind
 of metrics we might be interested in

---
 .../scala/kamon/metrics/MetricsExtension.scala     | 124 +++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 kamon-core/src/main/scala/kamon/metrics/MetricsExtension.scala

(limited to 'kamon-core/src/main/scala/kamon/metrics/MetricsExtension.scala')

diff --git a/kamon-core/src/main/scala/kamon/metrics/MetricsExtension.scala b/kamon-core/src/main/scala/kamon/metrics/MetricsExtension.scala
new file mode 100644
index 00000000..4bac3519
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metrics/MetricsExtension.scala
@@ -0,0 +1,124 @@
+/*
+ * =========================================================================================
+ * 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 scala.collection.concurrent.TrieMap
+import akka.actor.{ ExtensionIdProvider, ExtensionId, ExtendedActorSystem }
+import com.typesafe.config.Config
+import kamon.util.GlobPathFilter
+import kamon.Kamon
+import akka.actor
+import kamon.metrics.Metrics.MetricGroupFilter
+
+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[MetricSnapshot.Measurement]
+}
+
+object MetricSnapshot {
+  case class Measurement(value: Long, count: Long)
+}
+
+case class DefaultMetricSnapshot(numberOfMeasurements: Long, measurementLevels: Vector[MetricSnapshot.Measurement]) extends MetricSnapshot
+
+object MetricGroupIdentity {
+  trait Category {
+    def name: String
+  }
+}
+
+trait MetricGroupFactory {
+  type Group <: MetricGroupRecorder
+  def create(config: Config): Group
+}
+
+class MetricsExtension(val system: ExtendedActorSystem) extends Kamon.Extension {
+  val config = system.settings.config
+  val storage = TrieMap[MetricGroupIdentity, MetricGroupRecorder]()
+  val filters = loadFilters(config)
+
+  def register(name: String, category: MetricGroupIdentity.Category with MetricGroupFactory): Option[category.Group] = {
+    if (shouldTrack(name, category))
+      Some(storage.getOrElseUpdate(MetricGroupIdentity(name, category), category.create(config)).asInstanceOf[category.Group])
+    else
+      None
+  }
+
+  def unregister(name: String, category: MetricGroupIdentity.Category with MetricGroupFactory): Unit = {
+    storage.remove(MetricGroupIdentity(name, category))
+  }
+
+  def collect: Map[MetricGroupIdentity, MetricGroupSnapshot] = {
+    (for ((identity, recorder) ← storage) yield (identity, recorder.collect)).toMap
+  }
+
+  private def shouldTrack(name: String, category: MetricGroupIdentity.Category): Boolean = {
+    filters.get(category.name).map(filter ⇒ filter.accept(name)).getOrElse(false)
+  }
+
+  def loadFilters(config: Config): Map[String, MetricGroupFilter] = {
+    import scala.collection.JavaConverters._
+
+    val filters = config.getObjectList("kamon.metrics.filters").asScala
+
+    val allFilters =
+      for (
+        filter ← filters;
+        entry ← filter.entrySet().asScala
+      ) yield {
+        val key = entry.getKey
+        val keyBasedConfig = entry.getValue.atKey(key)
+
+        val includes = keyBasedConfig.getStringList(s"$key.includes").asScala.map(inc ⇒ new GlobPathFilter(inc)).toList
+        val excludes = keyBasedConfig.getStringList(s"$key.excludes").asScala.map(exc ⇒ new GlobPathFilter(exc)).toList
+
+        (key, MetricGroupFilter(includes, excludes))
+      }
+
+    allFilters.toMap
+  }
+
+}
+
+object Metrics extends ExtensionId[MetricsExtension] with ExtensionIdProvider {
+  def lookup(): ExtensionId[_ <: actor.Extension] = Metrics
+  def createExtension(system: ExtendedActorSystem): MetricsExtension = new MetricsExtension(system)
+
+  case class MetricGroupFilter(includes: List[GlobPathFilter], excludes: List[GlobPathFilter]) {
+    def accept(name: String): Boolean = includes.exists(_.accept(name)) && !excludes.exists(_.accept(name))
+  }
+}
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