heron/spi/src/java/org/apache/heron/spi/scheduler/ILauncher.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.heron.spi.scheduler;

import org.apache.heron.classification.InterfaceAudience;
import org.apache.heron.classification.InterfaceStability;
import org.apache.heron.spi.common.Config;
import org.apache.heron.spi.packing.PackingPlan;

/**
 * Launches scheduler. heron-cli will create Launcher object using default no argument constructor.
 */
@InterfaceAudience.LimitedPrivate
@InterfaceStability.Evolving
public interface ILauncher extends AutoCloseable {
  /**
   * Initialize Launcher with Config, Uploader and topology. These object
   * will be passed from submitter main. Config will contain information that launcher may use
   * to setup scheduler and other parameters required by launcher to contact
   * services which will launch scheduler.
   * @param config the config
   * @param runtime the runtime
   */
  void initialize(Config config, Config runtime);

  /**
   * This is to for disposing or cleaning up any internal state accumulated by
   * the ILauncher
   * <p>
   * Closes this stream and releases any system resources associated
   * with it. If the stream is already closed then invoking this
   * method has no effect.
   */
  void close();

  /**
   * Starts scheduler. Once this function returns successfully, heron-cli will terminate and
   * the launch process succeeded.
   *
   * @param packing Initial mapping suggested by running packing algorithm.
   * container_id-&gt;List of instance_id to be launched on this container.
   * @return true if topology launched successfully, false otherwise.
   */
  boolean launch(PackingPlan packing);
}