From 7307e1cc97e0363d1fb4cc116fc69a5272ca3730 Mon Sep 17 00:00:00 2001
From: Ivan Topolnak <itopolnak@despegar.com>
Date: Tue, 4 Feb 2014 15:58:30 -0300
Subject: metrics buffer for easier periodic reporting

---
 .../kamon/metrics/TickMetricSnapshotBuffer.scala   | 64 ++++++++++++++++++++++
 .../src/main/scala/kamon/metrics/package.scala     | 26 +++++++++
 .../main/scala/test/SimpleRequestProcessor.scala   |  6 +-
 3 files changed, 94 insertions(+), 2 deletions(-)
 create mode 100644 kamon-core/src/main/scala/kamon/metrics/TickMetricSnapshotBuffer.scala
 create mode 100644 kamon-core/src/main/scala/kamon/metrics/package.scala

diff --git a/kamon-core/src/main/scala/kamon/metrics/TickMetricSnapshotBuffer.scala b/kamon-core/src/main/scala/kamon/metrics/TickMetricSnapshotBuffer.scala
new file mode 100644
index 00000000..11c58cae
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metrics/TickMetricSnapshotBuffer.scala
@@ -0,0 +1,64 @@
+/*
+ * =========================================================================================
+ * 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 akka.actor.{Props, ActorRef, Actor}
+import kamon.metrics.Subscriptions.TickMetricSnapshot
+import kamon.metrics.TickMetricSnapshotBuffer.FlushBuffer
+import scala.concurrent.duration.FiniteDuration
+
+
+class TickMetricSnapshotBuffer(flushInterval: FiniteDuration, receiver: ActorRef) extends Actor {
+  val flushSchedule = context.system.scheduler.schedule(flushInterval, flushInterval, self, FlushBuffer)(context.dispatcher)
+
+  def receive = empty
+
+  def empty: Actor.Receive = {
+    case tick : TickMetricSnapshot  => context become(buffering(tick))
+    case FlushBuffer                => // Nothing to flush.
+  }
+
+  def buffering(buffered: TickMetricSnapshot): Actor.Receive = {
+    case TickMetricSnapshot(_, to, tickMetrics) =>
+      val combinedMetrics = combineMaps(buffered.metrics, tickMetrics)(mergeMetricGroup)
+      val combinedSnapshot = TickMetricSnapshot(buffered.from, to, combinedMetrics)
+
+      context become(buffering(combinedSnapshot))
+
+    case FlushBuffer =>
+      receiver ! buffered
+      context become(empty)
+
+  }
+
+
+  override def postStop(): Unit = {
+    flushSchedule.cancel()
+    super.postStop()
+  }
+
+  def mergeMetricGroup(left: MetricGroupSnapshot, right: MetricGroupSnapshot) = new MetricGroupSnapshot {
+    val metrics = combineMaps(left.metrics, right.metrics)((l, r) => l.merge(r))
+  }
+}
+
+object TickMetricSnapshotBuffer {
+  case object FlushBuffer
+
+  def props(flushInterval: FiniteDuration, receiver: ActorRef): Props =
+    Props[TickMetricSnapshotBuffer](new TickMetricSnapshotBuffer(flushInterval, receiver))
+}
diff --git a/kamon-core/src/main/scala/kamon/metrics/package.scala b/kamon-core/src/main/scala/kamon/metrics/package.scala
new file mode 100644
index 00000000..765ebaca
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metrics/package.scala
@@ -0,0 +1,26 @@
+/*
+ * =========================================================================================
+ * 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
+
+package object metrics {
+
+  def combineMaps[K, V](left: Map[K, V], right: Map[K, V])(valueMerger: (V, V) => V): Map[K, V] = {
+    (left ++ right) map {
+      case (key, rightValue) => key -> left.get(key).map(leftValue => valueMerger(leftValue, rightValue)).getOrElse(rightValue)
+    }
+  }
+}
diff --git a/kamon-playground/src/main/scala/test/SimpleRequestProcessor.scala b/kamon-playground/src/main/scala/test/SimpleRequestProcessor.scala
index cd497ca5..fb3d05d2 100644
--- a/kamon-playground/src/main/scala/test/SimpleRequestProcessor.scala
+++ b/kamon-playground/src/main/scala/test/SimpleRequestProcessor.scala
@@ -25,7 +25,7 @@ import scala.util.Random
 import akka.routing.RoundRobinRouter
 import kamon.trace.TraceRecorder
 import kamon.Kamon
-import kamon.metrics.{ ActorMetrics, TraceMetrics, Metrics }
+import kamon.metrics.{TickMetricSnapshotBuffer, ActorMetrics, TraceMetrics, Metrics}
 import spray.http.{ StatusCodes, Uri }
 import kamon.metrics.Subscriptions.TickMetricSnapshot
 import kamon.newrelic.WebTransactionMetrics
@@ -44,7 +44,9 @@ object SimpleRequestProcessor extends App with SimpleRoutingApp with RequestBuil
     def receive: Actor.Receive = { case any ⇒ sender ! any }
   }), "com")
 
-  Kamon(Metrics).subscribe(TraceMetrics, "*", printer, permanently = true)
+  val buffer = system.actorOf(TickMetricSnapshotBuffer.props(10 seconds, printer))
+
+  Kamon(Metrics).subscribe(TraceMetrics, "*", buffer, permanently = true)
   //Kamon(Metrics).subscribe(ActorMetrics, "*", printer, permanently = true)
 
   implicit val timeout = Timeout(30 seconds)
-- 
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