handle reporters shutdown and reconfigures

1 files changed, 209 insertions, 0 deletions

diff --git a/kamon-core/src/main/scala/kamon/ReporterRegistry.scala b/kamon-core/src/main/scala/kamon/ReporterRegistry.scala
new file mode 100644
index 00000000..09c980f6
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/ReporterRegistry.scala
@@ -0,0 +1,209 @@
+package kamon
+
+import java.time.Instant
+import java.util.concurrent.atomic.{AtomicLong, AtomicReference}
+import java.util.concurrent._
+
+import com.typesafe.config.Config
+import kamon.metric._
+import org.slf4j.LoggerFactory
+
+import scala.concurrent.{ExecutionContext, ExecutionContextExecutorService, Future}
+import scala.util.Try
+import scala.util.control.NonFatal
+
+trait ReporterRegistry {
+  def loadFromConfig(): Unit
+  def add(reporter: MetricsReporter): Registration
+  def add(reporter: MetricsReporter, name: String): Registration
+  def stopAll(): Future[Unit]
+}
+
+class ReporterRegistryImpl(metrics: RecorderRegistryImpl, initialConfig: Config) extends ReporterRegistry {
+  private val registryExecutionContext = Executors.newSingleThreadScheduledExecutor(threadFactory("kamon-reporter-registry"))
+  private val metricsTickerSchedule = new AtomicReference[ScheduledFuture[_]]()
+  private val metricReporters = new ConcurrentLinkedQueue[ReporterEntry]()
+  private val reporterCounter = new AtomicLong(0L)
+
+  reconfigure(initialConfig)
+
+  override def loadFromConfig(): Unit = ???
+
+  override def add(reporter: MetricsReporter): Registration =
+    add(reporter, reporter.getClass.getName())
+
+  override def add(reporter: MetricsReporter, name: String): Registration = {
+    val executor = Executors.newSingleThreadExecutor(threadFactory(name))
+    val reporterEntry = ReporterEntry(
+      id = reporterCounter.getAndIncrement(),
+      reporter = reporter,
+      executionContext = ExecutionContext.fromExecutorService(executor)
+    )
+
+    metricReporters.add(reporterEntry)
+
+    new Registration {
+      val reporterID = reporterEntry.id
+      override def cancel(): Boolean = {
+        metricReporters.removeIf(entry => {
+          if(entry.id == reporterID) {
+            stopReporter(entry)
+            true
+          } else false
+        })
+      }
+    }
+  }
+
+  override def stopAll(): Future[Unit] = {
+    implicit val stopReporterExeContext = ExecutionContext.fromExecutor(registryExecutionContext)
+    val reporterStopFutures = Vector.newBuilder[Future[Unit]]
+    while(!metricReporters.isEmpty) {
+      val entry = metricReporters.poll()
+      if(entry != null) {
+        reporterStopFutures += stopReporter(entry)
+      }
+    }
+
+    Future.sequence(reporterStopFutures.result()).transform(_ => Try((): Unit))
+  }
+
+  private[kamon] def reconfigure(config: Config): Unit = synchronized {
+    val tickInterval = config.getDuration("kamon.metric.tick-interval")
+    val currentTicker = metricsTickerSchedule.get()
+    if(currentTicker != null) {
+      currentTicker.cancel(true)
+    }
+
+    // Reconfigure all registered reporters
+    metricReporters.forEach(entry =>
+      Future(entry.reporter.reconfigure(config))(entry.executionContext)
+    )
+
+    metricsTickerSchedule.set {
+      registryExecutionContext.scheduleAtFixedRate(
+        new MetricTicker(metrics, metricReporters), tickInterval.toMillis, tickInterval.toMillis, TimeUnit.MILLISECONDS
+      )
+    }
+  }
+
+  private def stopReporter(entry: ReporterEntry): Future[Unit] = {
+    entry.isActive = false
+
+    Future(entry.reporter.stop())(entry.executionContext).andThen {
+      case _ => entry.executionContext.shutdown()
+    }(ExecutionContext.fromExecutor(registryExecutionContext))
+  }
+
+  /**
+    * Creates a thread factory that assigns the specified name to all created Threads.
+    */
+  private def threadFactory(name: String): ThreadFactory =
+    new ThreadFactory {
+      val defaultFactory = Executors.defaultThreadFactory()
+
+      override def newThread(r: Runnable): Thread = {
+        val thread = defaultFactory.newThread(r)
+        thread.setName(name)
+        thread
+      }
+    }
+
+
+  private case class ReporterEntry(
+    @volatile var isActive: Boolean = true,
+    id: Long,
+    reporter: MetricsReporter,
+    executionContext: ExecutionContextExecutorService
+  )
+
+  private class MetricTicker(metricsImpl: RecorderRegistryImpl, reporterEntries: java.util.Queue[ReporterEntry]) extends Runnable {
+    val logger = LoggerFactory.getLogger(classOf[MetricTicker])
+    var lastTick = Instant.now()
+
+    def run(): Unit = try {
+      val currentTick = Instant.now()
+      val tickSnapshot = TickSnapshot(
+        interval = Interval(lastTick, currentTick),
+        entities = metricsImpl.snapshot()
+      )
+
+      reporterEntries.forEach { entry =>
+        Future {
+          if(entry.isActive)
+            entry.reporter.processTick(tickSnapshot)
+
+        }(executor = entry.executionContext)
+      }
+
+      lastTick = currentTick
+
+    } catch {
+      case NonFatal(t) => logger.error("Error while running a tick", t)
+    }
+  }
+}
+
+
+
+trait Registration {
+  def cancel(): Boolean
+}
+
+trait MetricsReporter {
+  def reconfigure(config: Config): Unit
+
+  def start(config: Config): Unit
+  def stop(): Unit
+
+  def processTick(snapshot: TickSnapshot)
+}
+
+
+
+object TestingAllExample extends App {
+  val recorder = Kamon.metrics.getRecorder(Entity("topo", "human-being", Map.empty))
+
+  val registration = Kamon.reporters.add(new DummyReporter("test"))
+
+  var x = 0
+  while(true) {
+    recorder.counter("test-other").increment()
+    Thread.sleep(100)
+    x += 1
+
+    if(x == 50) {
+      registration.cancel()
+    }
+
+    if(x == 100) {
+      println("Stopping all reporters")
+      Kamon.reporters.stopAll()
+    }
+  }
+
+}
+
+
+class DummyReporter(name: String) extends MetricsReporter {
+  override def reconfigure(config: Config): Unit = {
+    println("NAME: " + name + "===> Reconfiguring Dummy")
+  }
+
+  override def start(config: Config): Unit = {
+
+    println("NAME: " + name + "===> Starting DUMMY")
+  }
+
+  override def stop(): Unit = {
+    println("NAME: " + name + "===> Stopping Dummy")
+  }
+
+  override def processTick(snapshot: TickSnapshot): Unit = {
+    println("NAME: " + name + s"===> [${Thread.currentThread().getName()}] Processing a tick in dummy." + snapshot)
+    println(s"From: ${snapshot.interval.from}, to: ${snapshot.interval.to}")
+    snapshot.entities.foreach { e =>
+      println(e.counters.map(c => s"Counter [${c.name}] => " + c.value).mkString(", "))
+    }
+  }
+}
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