From 7e74030ea824a6b6a561880103f69f3e8e409bba Mon Sep 17 00:00:00 2001
From: João Ferreira <jtjeferreira@gmail.com>
Date: Fri, 26 Jun 2015 17:47:00 +0100
Subject: + core: kamon.trace.token-generator conf

---
 kamon-core/src/main/resources/reference.conf               |  3 +++
 kamon-core/src/main/scala/kamon/trace/Sampler.scala        | 14 ++++++++++++++
 .../main/scala/kamon/trace/TracerExtensionSettings.scala   |  6 ++++--
 kamon-core/src/main/scala/kamon/trace/TracerModule.scala   | 12 +++---------
 4 files changed, 24 insertions(+), 11 deletions(-)

(limited to 'kamon-core/src/main')

diff --git a/kamon-core/src/main/resources/reference.conf b/kamon-core/src/main/resources/reference.conf
index a648c01a..c78d56cd 100644
--- a/kamon-core/src/main/resources/reference.conf
+++ b/kamon-core/src/main/resources/reference.conf
@@ -110,6 +110,9 @@ kamon {
       # must be power of two
       sample-interval = 8
     }
+    
+    # Fully qualified name of the function that will be used for generating tokens to traces.
+    token-generator = kamon.trace.DefaultTokenGenerator
 
     # Gather tracing information for all traces but only report those whose elapsed-time is equal or greated to the
     # .minimum-elapsed-time setting.
diff --git a/kamon-core/src/main/scala/kamon/trace/Sampler.scala b/kamon-core/src/main/scala/kamon/trace/Sampler.scala
index 5abba221..ac780d5e 100644
--- a/kamon-core/src/main/scala/kamon/trace/Sampler.scala
+++ b/kamon-core/src/main/scala/kamon/trace/Sampler.scala
@@ -16,9 +16,14 @@
 
 package kamon.trace
 
+import java.net.InetAddress
+import java.util.concurrent.atomic.AtomicLong
+
 import kamon.util.{ NanoInterval, Sequencer }
 import scala.concurrent.forkjoin.ThreadLocalRandom
 
+import scala.util.Try
+
 trait Sampler {
   def shouldTrace: Boolean
   def shouldReport(traceElapsedTime: NanoInterval): Boolean
@@ -71,3 +76,12 @@ class ThresholdSampler(thresholdInNanoseconds: Long) extends Sampler {
   def shouldReport(traceElapsedTime: NanoInterval): Boolean = traceElapsedTime.nanos >= thresholdInNanoseconds
 }
 
+class DefaultTokenGenerator extends Function0[String] {
+  private val _hostnamePrefix = Try(InetAddress.getLocalHost.getHostName).getOrElse("unknown-localhost")
+  private val _tokenCounter = new AtomicLong
+
+  def apply(): String = {
+    _hostnamePrefix + "-" + String.valueOf(_tokenCounter.incrementAndGet())
+  }
+}
+
diff --git a/kamon-core/src/main/scala/kamon/trace/TracerExtensionSettings.scala b/kamon-core/src/main/scala/kamon/trace/TracerExtensionSettings.scala
index 6167a007..80f59466 100644
--- a/kamon-core/src/main/scala/kamon/trace/TracerExtensionSettings.scala
+++ b/kamon-core/src/main/scala/kamon/trace/TracerExtensionSettings.scala
@@ -20,7 +20,7 @@ import java.util.concurrent.TimeUnit
 import kamon.util.ConfigTools.Syntax
 import com.typesafe.config.Config
 
-case class TraceSettings(levelOfDetail: LevelOfDetail, sampler: Sampler)
+case class TraceSettings(levelOfDetail: LevelOfDetail, sampler: Sampler, tokenGeneratorFQN: String)
 
 object TraceSettings {
   def apply(config: Config): TraceSettings = {
@@ -41,6 +41,8 @@ object TraceSettings {
         case "threshold" ⇒ new ThresholdSampler(tracerConfig.getFiniteDuration("threshold-sampler.minimum-elapsed-time").toNanos)
       }
 
-    TraceSettings(detailLevel, sampler)
+    val tokenGeneratorFQN = tracerConfig.getString("token-generator")
+
+    TraceSettings(detailLevel, sampler, tokenGeneratorFQN)
   }
 }
\ No newline at end of file
diff --git a/kamon-core/src/main/scala/kamon/trace/TracerModule.scala b/kamon-core/src/main/scala/kamon/trace/TracerModule.scala
index 416af20e..88464a30 100644
--- a/kamon-core/src/main/scala/kamon/trace/TracerModule.scala
+++ b/kamon-core/src/main/scala/kamon/trace/TracerModule.scala
@@ -16,17 +16,12 @@
 
 package kamon.trace
 
-import java.net.InetAddress
-import java.util.concurrent.atomic.AtomicLong
-
 import akka.actor._
 import com.typesafe.config.Config
 import kamon.Kamon
 import kamon.metric.MetricsModule
 import kamon.util._
 
-import scala.util.Try
-
 trait TracerModule {
   def newContext(name: String): TraceContext
   def newContext(name: String, token: Option[String]): TraceContext
@@ -96,14 +91,13 @@ object Tracer {
 
 private[kamon] class TracerModuleImpl(metricsExtension: MetricsModule, config: Config) extends TracerModule {
   private val _settings = TraceSettings(config)
-  private val _hostnamePrefix = Try(InetAddress.getLocalHost.getHostName).getOrElse("unknown-localhost")
-  private val _tokenCounter = new AtomicLong
 
   private val _subscriptions = new LazyActorRef
   private val _incubator = new LazyActorRef
+  private val _dynamic = new akka.actor.ReflectiveDynamicAccess(getClass.getClassLoader)
+  private val _tokenGenerator = _dynamic.createInstanceFor[Function0[String]](_settings.tokenGeneratorFQN, Nil).get // let's bubble up any problems.
 
-  private def newToken: String =
-    _hostnamePrefix + "-" + String.valueOf(_tokenCounter.incrementAndGet())
+  private def newToken: String = _tokenGenerator()
 
   def newContext(name: String): TraceContext =
     createTraceContext(name, None)
-- 
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