1 files changed, 92 insertions, 0 deletions
diff --git a/kamon-core/src/main/scala/kamon/ContextPropagation.scala b/kamon-core/src/main/scala/kamon/ContextPropagation.scala
new file mode 100644
index 00000000..8f2ed8e4
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/ContextPropagation.scala
@@ -0,0 +1,92 @@
+package kamon
+
+import com.typesafe.config.Config
+import kamon.context.BinaryPropagation.{ByteStreamReader, ByteStreamWriter}
+import kamon.context.HttpPropagation.{HeaderReader, HeaderWriter}
+import kamon.context.{BinaryPropagation, HttpPropagation, Propagation}
+
+trait ContextPropagation { self: Configuration with ClassLoading =>
+  @volatile private var _propagationComponents: ContextPropagation.Components = _
+  @volatile private var _defaultHttpPropagation: Propagation[HeaderReader, HeaderWriter] = _
+  @volatile private var _defaultBinaryPropagation: Propagation[ByteStreamReader, ByteStreamWriter] = _
+
+  // Initial configuration and reconfigures
+  init(self.config)
+  self.onReconfigure(newConfig => self.init(newConfig))
+
+
+  /**
+    * Retrieves the HTTP propagation channel with the supplied name. Propagation channels are configured on the
+    * kamon.propagation.http configuration section.
+    *
+    * @param channelName Channel name to retrieve.
+    * @return The HTTP propagation, if available.
+    */
+  def httpPropagation(channelName: String): Option[Propagation[HeaderReader, HeaderWriter]] =
+    _propagationComponents.httpChannels.get(channelName)
+
+  /**
+    * Retrieves the binary propagation channel with the supplied name. Propagation channels are configured on the
+    * kamon.propagation.binary configuration section.
+    *
+    * @param channelName Channel name to retrieve.
+    * @return The binary propagation, if available.
+    */
+  def binaryPropagation(channelName: String): Option[Propagation[ByteStreamReader, ByteStreamWriter]] =
+    _propagationComponents.binaryChannels.get(channelName)
+
+  /**
+    * Retrieves the default HTTP propagation channel. Configuration for this channel can be found under the
+    * kamon.propagation.http.default configuration section.
+    *
+    * @return The default HTTP propagation.
+    */
+  def defaultHttpPropagation(): Propagation[HeaderReader, HeaderWriter] =
+    _defaultHttpPropagation
+
+  /**
+    * Retrieves the default binary propagation channel. Configuration for this channel can be found under the
+    * kamon.propagation.binary.default configuration section.
+    *
+    * @return The default HTTP propagation.
+    */
+  def defaultBinaryPropagation(): Propagation[ByteStreamReader, ByteStreamWriter] =
+    _defaultBinaryPropagation
+
+
+
+  private def init(config: Config): Unit = synchronized {
+    _propagationComponents = ContextPropagation.Components.from(self.config, self)
+    _defaultHttpPropagation = _propagationComponents.httpChannels(ContextPropagation.DefaultHttpChannel)
+    _defaultBinaryPropagation = _propagationComponents.binaryChannels(ContextPropagation.DefaultBinaryChannel)
+  }
+}
+
+object ContextPropagation {
+  val DefaultHttpChannel = "default"
+  val DefaultBinaryChannel = "default"
+
+  case class Components(
+    httpChannels: Map[String, Propagation[HeaderReader, HeaderWriter]],
+    binaryChannels: Map[String, Propagation[ByteStreamReader, ByteStreamWriter]]
+  )
+
+  object Components {
+
+    def from(config: Config, classLoading: ClassLoading): Components = {
+      val propagationConfig = config.getConfig("kamon.propagation")
+      val httpChannelsConfig = propagationConfig.getConfig("http").configurations
+      val binaryChannelsConfig = propagationConfig.getConfig("binary").configurations
+
+      val httpChannels = httpChannelsConfig.map {
+        case (channelName, channelConfig) => (channelName -> HttpPropagation.from(channelConfig, classLoading))
+      }
+
+      val binaryChannels = binaryChannelsConfig.map {
+        case (channelName, channelConfig) => (channelName -> BinaryPropagation.from(channelConfig, classLoading))
+      }
+
+      Components(httpChannels, binaryChannels)
+    }
+  }
+}