1 files changed, 101 insertions, 0 deletions
diff --git a/container-di/src/main/scala/com/yahoo/container/di/ConfigRetriever.scala b/container-di/src/main/scala/com/yahoo/container/di/ConfigRetriever.scala
new file mode 100644
index 00000000000..a1b8167171a
--- /dev/null
+++ b/container-di/src/main/scala/com/yahoo/container/di/ConfigRetriever.scala
@@ -0,0 +1,101 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.container.di
+
+
+import config.Subscriber
+import java.util.logging.Logger
+import com.yahoo.log.LogLevel
+import ConfigRetriever._
+import annotation.tailrec
+import com.yahoo.config.ConfigInstance
+import scala.collection.JavaConversions._
+import com.yahoo.vespa.config.ConfigKey
+
+/**
+ * @author tonytv
+ * @author gjoranv
+ */
+final class ConfigRetriever(bootstrapKeys: Set[ConfigKeyT],
+                            subscribe: Set[ConfigKeyT] => Subscriber)
+{
+  require(!bootstrapKeys.isEmpty)
+
+  private val bootstrapSubscriber: Subscriber = subscribe(bootstrapKeys)
+
+  private var componentSubscriber: Subscriber = subscribe(Set())
+  private var componentSubscriberKeys: Set[ConfigKeyT] = Set()
+
+
+  @tailrec
+  final def getConfigs(componentConfigKeys: Set[ConfigKeyT], leastGeneration: Long): ConfigSnapshot = {
+    require(componentConfigKeys intersect bootstrapKeys isEmpty)
+    log.log(LogLevel.DEBUG, "getConfigs: " + componentConfigKeys)
+
+    setupComponentSubscriber(componentConfigKeys ++ bootstrapKeys)
+
+    getConfigsOptional(leastGeneration) match {
+      case Some(snapshot) => resetComponentSubscriberIfBootstrap(snapshot); snapshot
+      case None => getConfigs(componentConfigKeys, leastGeneration)
+    }
+  }
+
+  private def getConfigsOptional(leastGeneration: Long): Option[ConfigSnapshot] = {
+    val newestComponentGeneration = componentSubscriber.waitNextGeneration()
+
+    if (newestComponentGeneration < leastGeneration) {
+      None
+    } else if (bootstrapSubscriber.generation < newestComponentGeneration) {
+      val newestBootstrapGeneration = bootstrapSubscriber.waitNextGeneration()
+      bootstrapConfigIfChanged() orElse {
+        if (newestBootstrapGeneration == newestComponentGeneration) componentsConfigIfChanged()
+        else None
+      }
+    } else {
+      componentsConfigIfChanged()
+    }
+  }
+
+  private def bootstrapConfigIfChanged():  Option[BootstrapConfigs]  = configIfChanged(bootstrapSubscriber, BootstrapConfigs)
+  private def componentsConfigIfChanged(): Option[ComponentsConfigs] = configIfChanged(componentSubscriber, ComponentsConfigs)
+
+  private def configIfChanged[T <: ConfigSnapshot](subscriber: Subscriber,
+                                                   constructor: Map[ConfigKeyT, ConfigInstance] => T ):
+  Option[T] = {
+    if (subscriber.configChanged) Some(constructor(subscriber.config.toMap))
+    else None
+  }
+
+  private def resetComponentSubscriberIfBootstrap(snapshot: ConfigSnapshot) {
+    snapshot match {
+      case BootstrapConfigs(_) => setupComponentSubscriber(Set())
+      case _ =>
+    }
+  }
+
+  private def setupComponentSubscriber(keys: Set[ConfigKeyT]) {
+    if (componentSubscriberKeys != keys) {
+      componentSubscriber.close()
+
+      componentSubscriberKeys = keys
+      componentSubscriber = subscribe(keys)
+    }
+  }
+
+  def shutdown() {
+    bootstrapSubscriber.close()
+    componentSubscriber.close()
+  }
+
+  //TODO: check if these are really needed
+  final def getBootstrapGeneration = bootstrapSubscriber.generation
+  final def getComponentsGeneration = componentSubscriber.generation
+}
+
+
+object ConfigRetriever {
+  private val log = Logger.getLogger(classOf[ConfigRetriever].getName)
+
+  sealed abstract class ConfigSnapshot
+  case class BootstrapConfigs(configs: Map[ConfigKeyT, ConfigInstance]) extends ConfigSnapshot
+  case class ComponentsConfigs(configs: Map[ConfigKeyT, ConfigInstance]) extends ConfigSnapshot
+}