From 01a34f67ff75419c440f2e69c0a0db888a670a34 Mon Sep 17 00:00:00 2001
From: Ivan Topolnjak <ivantopo@gmail.com>
Date: Mon, 12 Jan 2015 01:45:27 +0100
Subject: ! all: improve the metric recorders infrastructure

---
 .../kamon/metric/SubscriptionsDispatcher.scala     | 115 +++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 kamon-core/src/main/scala/kamon/metric/SubscriptionsDispatcher.scala

(limited to 'kamon-core/src/main/scala/kamon/metric/SubscriptionsDispatcher.scala')

diff --git a/kamon-core/src/main/scala/kamon/metric/SubscriptionsDispatcher.scala b/kamon-core/src/main/scala/kamon/metric/SubscriptionsDispatcher.scala
new file mode 100644
index 00000000..f616be35
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metric/SubscriptionsDispatcher.scala
@@ -0,0 +1,115 @@
+/*
+ * =========================================================================================
+ * 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.metric
+
+import akka.actor._
+import kamon.metric.SubscriptionsDispatcher._
+import kamon.util.{ MilliTimestamp, GlobPathFilter }
+import scala.concurrent.duration.FiniteDuration
+
+/**
+ *  Manages subscriptions to metrics and dispatch snapshots on every tick to all subscribers.
+ */
+private[kamon] class SubscriptionsDispatcher(interval: FiniteDuration, collector: () ⇒ Map[Entity, EntitySnapshot]) extends Actor {
+  var lastTick = MilliTimestamp.now
+  var oneShotSubscriptions = Map.empty[ActorRef, SubscriptionFilter]
+  var permanentSubscriptions = Map.empty[ActorRef, SubscriptionFilter]
+  val tickSchedule = context.system.scheduler.schedule(interval, interval, self, Tick)(context.dispatcher)
+
+  def receive = {
+    case Tick                                       ⇒ processTick()
+    case Subscribe(filter, subscriber, permanently) ⇒ subscribe(filter, subscriber, permanently)
+    case Unsubscribe(subscriber)                    ⇒ unsubscribe(subscriber)
+    case Terminated(subscriber)                     ⇒ unsubscribe(subscriber)
+  }
+
+  def processTick(): Unit =
+    dispatch(collector())
+
+  def subscribe(filter: SubscriptionFilter, subscriber: ActorRef, permanent: Boolean): Unit = {
+    def addSubscription(storage: Map[ActorRef, SubscriptionFilter]): Map[ActorRef, SubscriptionFilter] =
+      storage.updated(subscriber, storage.getOrElse(subscriber, SubscriptionFilter.Empty).combine(filter))
+
+    context.watch(subscriber)
+
+    if (permanent)
+      permanentSubscriptions = addSubscription(permanentSubscriptions)
+    else
+      oneShotSubscriptions = addSubscription(oneShotSubscriptions)
+  }
+
+  def unsubscribe(subscriber: ActorRef): Unit = {
+    permanentSubscriptions = permanentSubscriptions - subscriber
+    oneShotSubscriptions = oneShotSubscriptions - subscriber
+  }
+
+  def dispatch(snapshots: Map[Entity, EntitySnapshot]): Unit = {
+    val currentTick = MilliTimestamp.now
+
+    dispatchSelections(lastTick, currentTick, permanentSubscriptions, snapshots)
+    dispatchSelections(lastTick, currentTick, oneShotSubscriptions, snapshots)
+
+    lastTick = currentTick
+    oneShotSubscriptions = Map.empty[ActorRef, SubscriptionFilter]
+  }
+
+  def dispatchSelections(lastTick: MilliTimestamp, currentTick: MilliTimestamp, subscriptions: Map[ActorRef, SubscriptionFilter],
+    snapshots: Map[Entity, EntitySnapshot]): Unit = {
+
+    for ((subscriber, filter) ← subscriptions) {
+      val selection = snapshots.filter(group ⇒ filter.accept(group._1))
+      val tickMetrics = TickMetricSnapshot(lastTick, currentTick, selection)
+
+      subscriber ! tickMetrics
+    }
+  }
+}
+
+object SubscriptionsDispatcher {
+  def props(interval: FiniteDuration, collector: () ⇒ Map[Entity, EntitySnapshot]): Props =
+    Props(new SubscriptionsDispatcher(interval, collector))
+
+  case object Tick
+  case class Unsubscribe(subscriber: ActorRef)
+  case class Subscribe(filter: SubscriptionFilter, subscriber: ActorRef, permanently: Boolean = false)
+  case class TickMetricSnapshot(from: MilliTimestamp, to: MilliTimestamp, metrics: Map[Entity, EntitySnapshot])
+
+}
+
+trait SubscriptionFilter { self ⇒
+
+  def accept(entity: Entity): Boolean
+
+  final def combine(that: SubscriptionFilter): SubscriptionFilter = new SubscriptionFilter {
+    override def accept(entity: Entity): Boolean = self.accept(entity) || that.accept(entity)
+  }
+}
+
+object SubscriptionFilter {
+  val Empty = new SubscriptionFilter {
+    def accept(entity: Entity): Boolean = false
+  }
+
+  def apply(category: String, name: String): SubscriptionFilter = new SubscriptionFilter {
+    val categoryPattern = new GlobPathFilter(category)
+    val namePattern = new GlobPathFilter(name)
+
+    def accept(entity: Entity): Boolean = {
+      categoryPattern.accept(entity.category) && namePattern.accept(entity.name)
+    }
+  }
+}
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