1 files changed, 173 insertions, 0 deletions
diff --git a/kamon-core/src/main/scala/kamon/metric/Subscriptions.scala b/kamon-core/src/main/scala/kamon/metric/Subscriptions.scala
new file mode 100644
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+++ b/kamon-core/src/main/scala/kamon/metric/Subscriptions.scala
@@ -0,0 +1,173 @@
+/*
+ * =========================================================================================
+ * 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.Subscriptions._
+import kamon.util.GlobPathFilter
+import scala.concurrent.duration.{ FiniteDuration, Duration }
+import java.util.concurrent.TimeUnit
+import kamon.Kamon
+import kamon.metric.TickMetricSnapshotBuffer.FlushBuffer
+
+class Subscriptions extends Actor {
+  import context.system
+
+  val flushMetricsSchedule = scheduleFlushMessage()
+  val collectionContext = Kamon(Metrics).buildDefaultCollectionContext
+
+  var lastTick: Long = System.currentTimeMillis()
+  var oneShotSubscriptions: Map[ActorRef, MetricSelectionFilter] = Map.empty
+  var permanentSubscriptions: Map[ActorRef, MetricSelectionFilter] = Map.empty
+
+  def receive = {
+    case Subscribe(category, selection, subscriber, permanent) ⇒ subscribe(category, selection, subscriber, permanent)
+    case Unsubscribe(subscriber) ⇒ unsubscribe(subscriber)
+    case Terminated(subscriber) ⇒ unsubscribe(subscriber)
+    case FlushMetrics ⇒ flush()
+  }
+
+  def subscribe(category: MetricGroupCategory, selection: String, subscriber: ActorRef, permanent: Boolean): Unit = {
+    context.watch(subscriber)
+    val newFilter: MetricSelectionFilter = GroupAndPatternFilter(category, new GlobPathFilter(selection))
+
+    if (permanent) {
+      permanentSubscriptions = permanentSubscriptions.updated(subscriber, newFilter combine {
+        permanentSubscriptions.getOrElse(subscriber, MetricSelectionFilter.empty)
+      })
+    } else {
+      oneShotSubscriptions = oneShotSubscriptions.updated(subscriber, newFilter combine {
+        oneShotSubscriptions.getOrElse(subscriber, MetricSelectionFilter.empty)
+      })
+    }
+  }
+
+  def unsubscribe(subscriber: ActorRef): Unit = {
+    if (permanentSubscriptions.contains(subscriber))
+      permanentSubscriptions = permanentSubscriptions - subscriber
+
+    if (oneShotSubscriptions.contains(subscriber))
+      oneShotSubscriptions = oneShotSubscriptions - subscriber
+  }
+
+  def flush(): Unit = {
+    val currentTick = System.currentTimeMillis()
+    val snapshots = collectAll()
+
+    dispatchSelectedMetrics(lastTick, currentTick, permanentSubscriptions, snapshots)
+    dispatchSelectedMetrics(lastTick, currentTick, oneShotSubscriptions, snapshots)
+
+    lastTick = currentTick
+    oneShotSubscriptions = Map.empty
+  }
+
+  def collectAll(): Map[MetricGroupIdentity, MetricGroupSnapshot] = {
+    val allMetrics = Kamon(Metrics).storage
+    val builder = Map.newBuilder[MetricGroupIdentity, MetricGroupSnapshot]
+
+    allMetrics.foreach {
+      case (identity, recorder) ⇒ builder += ((identity, recorder.collect(collectionContext)))
+    }
+
+    builder.result()
+  }
+
+  def dispatchSelectedMetrics(lastTick: Long, currentTick: Long, subscriptions: Map[ActorRef, MetricSelectionFilter],
+    snapshots: Map[MetricGroupIdentity, MetricGroupSnapshot]): Unit = {
+
+    for ((subscriber, filter) ← subscriptions) {
+      val selection = snapshots.filter(group ⇒ filter.accept(group._1))
+      val tickMetrics = TickMetricSnapshot(lastTick, currentTick, selection)
+
+      subscriber ! tickMetrics
+    }
+  }
+
+  def scheduleFlushMessage(): Cancellable = {
+    val config = context.system.settings.config
+    val tickInterval = Duration(config.getDuration("kamon.metrics.tick-interval", TimeUnit.NANOSECONDS), TimeUnit.NANOSECONDS)
+    context.system.scheduler.schedule(tickInterval, tickInterval, self, FlushMetrics)(context.dispatcher)
+  }
+}
+
+object Subscriptions {
+  case object FlushMetrics
+  case class Unsubscribe(subscriber: ActorRef)
+  case class Subscribe(category: MetricGroupCategory, selection: String, subscriber: ActorRef, permanently: Boolean = false)
+  case class TickMetricSnapshot(from: Long, to: Long, metrics: Map[MetricGroupIdentity, MetricGroupSnapshot])
+
+  trait MetricSelectionFilter {
+    def accept(identity: MetricGroupIdentity): Boolean
+  }
+
+  object MetricSelectionFilter {
+    val empty = new MetricSelectionFilter {
+      def accept(identity: MetricGroupIdentity): Boolean = false
+    }
+
+    implicit class CombinableMetricSelectionFilter(msf: MetricSelectionFilter) {
+      def combine(that: MetricSelectionFilter): MetricSelectionFilter = new MetricSelectionFilter {
+        def accept(identity: MetricGroupIdentity): Boolean = msf.accept(identity) || that.accept(identity)
+      }
+    }
+  }
+
+  case class GroupAndPatternFilter(category: MetricGroupCategory, globFilter: GlobPathFilter) extends MetricSelectionFilter {
+    def accept(identity: MetricGroupIdentity): Boolean = {
+      category.equals(identity.category) && globFilter.accept(identity.name)
+    }
+  }
+}
+
+class TickMetricSnapshotBuffer(flushInterval: FiniteDuration, receiver: ActorRef) extends Actor {
+  val flushSchedule = context.system.scheduler.schedule(flushInterval, flushInterval, self, FlushBuffer)(context.dispatcher)
+  val collectionContext = Kamon(Metrics)(context.system).buildDefaultCollectionContext
+
+  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) = left.merge(right.asInstanceOf[left.GroupSnapshotType], collectionContext).asInstanceOf[MetricGroupSnapshot] // ??? //Combined(combineMaps(left.metrics, right.metrics)((l, r) ⇒ l.merge(r, collectionContext)))
+}
+
+object TickMetricSnapshotBuffer {
+  case object FlushBuffer
+
+  def props(flushInterval: FiniteDuration, receiver: ActorRef): Props =
+    Props[TickMetricSnapshotBuffer](new TickMetricSnapshotBuffer(flushInterval, receiver))
+}