/* ===================================================
 * Copyright © 2013 the kamon project <http://kamon.io/>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ========================================================== */
package kamon

import akka.actor.{ Extension, ActorSystem, ExtensionId }
import java.util.concurrent.ConcurrentHashMap

object AkkaExtensionSwap {
  def swap(system: ActorSystem, key: ExtensionId[_], value: Extension): Unit = {
    val extensionsField = system.getClass.getDeclaredField("extensions")
    extensionsField.setAccessible(true)

    val extensions = extensionsField.get(system).asInstanceOf[ConcurrentHashMap[ExtensionId[_], AnyRef]]
    extensions.put(key, value)
  }
}