1 files changed, 96 insertions, 0 deletions
diff --git a/kamon-system-metrics/src/main/scala/kamon/system/custom/ContextSwitchesMetrics.scala b/kamon-system-metrics/src/main/scala/kamon/system/custom/ContextSwitchesMetrics.scala
new file mode 100644
index 00000000..a3c56733
--- /dev/null
+++ b/kamon-system-metrics/src/main/scala/kamon/system/custom/ContextSwitchesMetrics.scala
@@ -0,0 +1,96 @@
+package kamon.system.custom
+
+import java.io.IOException
+import java.nio.charset.StandardCharsets
+import java.nio.file.{ Paths, Files }
+
+import akka.actor.{ Props, Actor, ActorSystem }
+import akka.event.{ Logging, LoggingAdapter }
+import kamon.Kamon
+import kamon.metric._
+import kamon.metric.instrument.InstrumentFactory
+import kamon.system.custom.ContextSwitchesUpdater.UpdateContextSwitches
+import org.hyperic.sigar.Sigar
+import scala.collection.JavaConverters.iterableAsScalaIterableConverter
+import scala.concurrent.duration.FiniteDuration
+
+class ContextSwitchesMetrics(pid: Long, log: LoggingAdapter, instrumentFactory: InstrumentFactory) extends GenericEntityRecorder(instrumentFactory) {
+  val perProcessVoluntary = histogram("context-switches-process-voluntary")
+  val perProcessNonVoluntary = histogram("context-switches-process-non-voluntary")
+  val global = histogram("context-switches-global")
+
+  def update(): Unit = {
+    def contextSwitchesByProcess(pid: Long): (Long, Long) = {
+      val filename = s"/proc/$pid/status"
+      var voluntaryContextSwitches = 0L
+      var nonVoluntaryContextSwitches = 0L
+
+      try {
+        for (line ← Files.readAllLines(Paths.get(filename), StandardCharsets.US_ASCII).asScala.toList) {
+          if (line.startsWith("voluntary_ctxt_switches")) {
+            voluntaryContextSwitches = line.substring(line.indexOf(":") + 1).trim.toLong
+          }
+          if (line.startsWith("nonvoluntary_ctxt_switches")) {
+            nonVoluntaryContextSwitches = line.substring(line.indexOf(":") + 1).trim.toLong
+          }
+        }
+      } catch {
+        case ex: IOException ⇒ log.error("Error trying to read [{}]", filename)
+      }
+      (voluntaryContextSwitches, nonVoluntaryContextSwitches)
+    }
+
+    def contextSwitches: Long = {
+      val filename = "/proc/stat"
+      var contextSwitches = 0L
+
+      try {
+        for (line ← Files.readAllLines(Paths.get(filename), StandardCharsets.US_ASCII).asScala.toList) {
+          if (line.startsWith("rcs")) {
+            contextSwitches = line.substring(line.indexOf(" ") + 1).toLong
+          }
+        }
+      } catch {
+        case ex: IOException ⇒ log.error("Error trying to read [{}]", filename)
+      }
+      contextSwitches
+    }
+
+    val (voluntary, nonVoluntary) = contextSwitchesByProcess(pid)
+    perProcessVoluntary.record(voluntary)
+    perProcessNonVoluntary.record(nonVoluntary)
+    global.record(contextSwitches)
+  }
+}
+
+object ContextSwitchesMetrics {
+
+  def register(system: ActorSystem, refreshInterval: FiniteDuration): ContextSwitchesMetrics = {
+    val metricsExtension = Kamon(Metrics)(system)
+    val log = Logging(system, "ContextSwitchesMetrics")
+    val pid = (new Sigar).getPid
+
+    val instrumentFactory = metricsExtension.instrumentFactory("system-metric")
+    metricsExtension.register(Entity("context-switches", "system-metric"), new ContextSwitchesMetrics(pid, log, instrumentFactory)).recorder
+  }
+}
+
+class ContextSwitchesUpdater(csm: ContextSwitchesMetrics, refreshInterval: FiniteDuration) extends Actor {
+  val schedule = context.system.scheduler.schedule(refreshInterval, refreshInterval, self, UpdateContextSwitches)(context.dispatcher)
+
+  def receive = {
+    case UpdateContextSwitches ⇒ csm.update()
+  }
+
+  override def postStop(): Unit = {
+    schedule.cancel()
+    super.postStop()
+  }
+}
+
+object ContextSwitchesUpdater {
+  case object UpdateContextSwitches
+
+  def props(csm: ContextSwitchesMetrics, refreshInterval: FiniteDuration): Props =
+    Props(new ContextSwitchesUpdater(csm, refreshInterval))
+}
+\ No newline at end of file