io.gatling.http.resolver.ShuffleJdkNameResolver.scala Maven / Gradle / Ivy

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/**
 * Copyright 2011-2016 GatlingCorp (http://gatling.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 io.gatling.http.resolver

import java.net.{ UnknownHostException, InetAddress }
import java.util.{ Arrays => JArrays, Collections => JCollections, List => JList }
import java.util.concurrent.ConcurrentHashMap

import io.netty.resolver.InetNameResolver
import io.netty.util.concurrent.{ Promise, ImmediateEventExecutor }

class ShuffleJdkNameResolver extends InetNameResolver(ImmediateEventExecutor.INSTANCE) {

  private[this] val cache = new ConcurrentHashMap[String, JList[InetAddress]]

  override def doResolve(inetHost: String, promise: Promise[InetAddress]): Unit =
    throw new UnsupportedOperationException

  override def doResolveAll(inetHost: String, promise: Promise[JList[InetAddress]]): Unit =
    try {
      var addresses = cache.get(inetHost)
      if (addresses == null) {
        addresses = InetAddress.getAllByName(inetHost) match {
          case Array(single) => JCollections.singletonList(single)
          case array =>
            val list = JArrays.asList(InetAddress.getAllByName(inetHost): _*)
            JCollections.shuffle(list)
            list
        }

        val oldAddresses = cache.putIfAbsent(inetHost, addresses)
        if (oldAddresses != null) {
          // concurrent update
          addresses = oldAddresses
        }
      }
      promise.setSuccess(addresses)
    } catch {
      case e: UnknownHostException => promise.setFailure(e)
    }
}