! statsd,datadog: reformat metric names to get a better display of automatically named traces, closes #35

After a bit of testing it seems like instead of  generating more friendly names by default, we need to do
changes that are specific to each module (StatsD and Datadog) in order to make it work properly. Here is
a list of the introduced changes:
  - StatsD
    - Change dots (.) to underscores (_) on the host name string.
    - Change ': ' to single underscore and spaced to underscore. Userful for automatically generated http
      trace names.
    - Change '/' to underscore. Ideally the dashboard could replace '_' with '/' to display it like a path.

  - Datadog
    - Change ': ' to ':'. Userful for automatically generated http trace names.

2 files changed, 24 insertions, 9 deletions

diff --git a/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala b/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
index dcd78f78..299b1acc 100644
--- a/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
+++ b/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
@@ -32,6 +32,8 @@ object StatsD extends ExtensionId[StatsDExtension] with ExtensionIdProvider {
   override def createExtension(system: ExtendedActorSystem): StatsDExtension = new StatsDExtension(system)
 
   trait MetricKeyGenerator {
+    def localhostName: String
+    def normalizedLocalhostName: String
     def generateKey(groupIdentity: MetricGroupIdentity, metricIdentity: MetricIdentity): String
   }
 }
@@ -69,22 +71,34 @@ class StatsDExtension(system: ExtendedActorSystem) extends Kamon.Extension {
 
   def buildMetricsListener(tickInterval: Long, flushInterval: Long): ActorRef = {
     assert(flushInterval >= tickInterval, "StatsD flush-interval needs to be equal or greater to the tick-interval")
+    val defaultMetricKeyGenerator = new SimpleMetricKeyGenerator(system.settings.config)
+
+    val metricsSender = system.actorOf(StatsDMetricsSender.props(
+      statsDHost,
+      maxPacketSizeInBytes,
+      defaultMetricKeyGenerator), "statsd-metrics-sender")
 
-    val metricsTranslator = system.actorOf(StatsDMetricsSender.props(statsDHost, maxPacketSizeInBytes), "statsd-metrics-sender")
     if (flushInterval == tickInterval) {
       // No need to buffer the metrics, let's go straight to the metrics sender.
-      metricsTranslator
+      metricsSender
     } else {
-      system.actorOf(TickMetricSnapshotBuffer.props(flushInterval.toInt.millis, metricsTranslator), "statsd-metrics-buffer")
+      system.actorOf(TickMetricSnapshotBuffer.props(flushInterval.toInt.millis, metricsSender), "statsd-metrics-buffer")
     }
   }
 }
 
 class SimpleMetricKeyGenerator(config: Config) extends StatsD.MetricKeyGenerator {
   val application = config.getString("kamon.statsd.simple-metric-key-generator.application")
-  val localhostName = ManagementFactory.getRuntimeMXBean.getName.split('@')(1)
+  val _localhostName = ManagementFactory.getRuntimeMXBean.getName.split('@')(1)
+  val _normalizedLocalhostName = _localhostName.replace('.', '_')
+
+  def localhostName: String = _localhostName
 
-  def generateKey(groupIdentity: MetricGroupIdentity, metricIdentity: MetricIdentity): String =
-    s"${application}.${localhostName}.${groupIdentity.category.name}.${groupIdentity.name}.${metricIdentity.name}"
+  def normalizedLocalhostName: String = _normalizedLocalhostName
+
+  def generateKey(groupIdentity: MetricGroupIdentity, metricIdentity: MetricIdentity): String = {
+    val normalizedGroupName = groupIdentity.name.replace(": ", "-").replace(" ", "_").replace("/", "_")
+    s"${application}.${normalizedLocalhostName}.${groupIdentity.category.name}.${normalizedGroupName}.${metricIdentity.name}"
+  }
 }
 
diff --git a/kamon-statsd/src/main/scala/kamon/statsd/StatsDMetricsSender.scala b/kamon-statsd/src/main/scala/kamon/statsd/StatsDMetricsSender.scala
index 94bab27c..8fbf4fee 100644
--- a/kamon-statsd/src/main/scala/kamon/statsd/StatsDMetricsSender.scala
+++ b/kamon-statsd/src/main/scala/kamon/statsd/StatsDMetricsSender.scala
@@ -26,10 +26,10 @@ import java.util.Locale
 
 import kamon.metric.instrument.{ Counter, Histogram }
 
-class StatsDMetricsSender(remote: InetSocketAddress, maxPacketSizeInBytes: Long) extends Actor with UdpExtensionProvider {
+class StatsDMetricsSender(remote: InetSocketAddress, maxPacketSizeInBytes: Long, metricKeyGenerator: StatsD.MetricKeyGenerator)
+    extends Actor with UdpExtensionProvider {
   import context.system
 
-  val metricKeyGenerator = new SimpleMetricKeyGenerator(context.system.settings.config)
   val symbols = DecimalFormatSymbols.getInstance(Locale.US)
   symbols.setDecimalSeparator('.') // Just in case there is some weird locale config we are not aware of.
 
@@ -80,7 +80,8 @@ class StatsDMetricsSender(remote: InetSocketAddress, maxPacketSizeInBytes: Long)
 }
 
 object StatsDMetricsSender {
-  def props(remote: InetSocketAddress, maxPacketSize: Long): Props = Props(new StatsDMetricsSender(remote, maxPacketSize))
+  def props(remote: InetSocketAddress, maxPacketSize: Long, metricKeyGenerator: StatsD.MetricKeyGenerator): Props =
+    Props(new StatsDMetricsSender(remote, maxPacketSize, metricKeyGenerator))
 }
 
 trait UdpExtensionProvider {