com.netflix.spinnaker.q.MessageHandler.kt Maven / Gradle / Ivy

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/*
 * Copyright 2017 Netflix, Inc.
 *
 * 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 com.netflix.spinnaker.q

/**
 * Implementations handle a single [Message] type from the [Queue].
 */
interface MessageHandler : (Message) -> Unit {

  val messageType: Class
  val queue: Queue

  /**
   * Passes [message] to [handle] if it is an instance of [messageType].
   *
   * @throws IllegalArgumentException if [message] is not an instance of
   * [messageType].
   */
  override fun invoke(message: Message): Unit =
    if (messageType.isAssignableFrom(message.javaClass)) {
      @Suppress("UNCHECKED_CAST")
      handle(message as M)
    } else {
      throw IllegalArgumentException("Unsupported message type ${message.javaClass.simpleName}")
    }

  /**
   * Process [message].
   */
  fun handle(message: M): Unit
}