IScheduler.java

// Copyright 2016 Twitter. All rights reserved.
//
// 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.twitter.heron.spi.scheduler;

import java.util.List;

import com.twitter.heron.classification.InterfaceAudience;
import com.twitter.heron.classification.InterfaceStability;
import com.twitter.heron.proto.scheduler.Scheduler;
import com.twitter.heron.spi.common.Config;
import com.twitter.heron.spi.packing.PackingPlan;

/**
 * Scheduler object responsible for bringing up topology. Will be instantiated using no-arg
 * constructor.
 */
@InterfaceAudience.LimitedPrivate
@InterfaceStability.Evolving
public interface IScheduler extends AutoCloseable {
  /**
   * This will initialize scheduler using config file. Will be called during start.
   */
  void initialize(Config config, Config runtime);

  /**
   * This is to for disposing or cleaning up any internal state accumulated by
   * the scheduler
   * <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();

  /**
   * This method will be called after initialize.
   * It is responsible for grabbing resource to launch executor and make sure they
   * get launched.
   * <p>
   *
   * @param packing Initial mapping suggested by running packing algorithm.
   */
  boolean onSchedule(PackingPlan packing);

  /**
   * This method will be called after onScheduler
   * It is responsible to return links to topology's customized ui pages.
   * Example: link to the Mesos Slave UI page displaying all scheduled containers
   *
   * @return the links if any customized page. It returns an empty list if no any links
   */
  List<String> getJobLinks();

  /**
   * Called by SchedulerServer when it receives a http request to kill topology,
   * while the http request body would be the protobuf Scheduler.KillTopologyRequest.
   * The SchedulerServer would parse the request body and feed with this method.
   * It would be invoked in the executors of SchedulerServer.
   *
   * @param request The KillTopologyRequest sent from local heron-cli
   * @return true if the IScheduler kills the topology successfully. SchedulerServer would
   * send KillTopologyResponse correspondingly according to this method's return value.
   */
  boolean onKill(Scheduler.KillTopologyRequest request);

  /**
   * Called by SchedulerServer when it receives a http request to restart topology,
   * while the http request body would be the protobuf Scheduler.RestartTopologyRequest.
   * The SchedulerServer would parse the request body and feed with this method.
   * It would be invoked in the executors of SchedulerServer.
   *
   * @param request The RestartTopologyRequest sent from local heron-cli
   * @return true if the IScheduler restarts the topology successfully. SchedulerServer would
   * send RestartTopologyResponse correspondingly according to this method's return value.
   */
  boolean onRestart(Scheduler.RestartTopologyRequest request);

  /**
   * Called by SchedulerServer when it receives a http request to update topology,
   * while the http request body would be the protobuf Scheduler.UpdateTopologyRequest.
   * The SchedulerServer would parse the request body and feed with this method.
   * It would be invoked in the executors of SchedulerServer.
   *
   * @param request The UpdateTopologyRequest sent from local heron-cli
   * @return true if the IScheduler updates the topology successfully. SchedulerServer would
   * send UpdateTopologyResponse correspondingly according to this method's return value.
   */
  boolean onUpdate(Scheduler.UpdateTopologyRequest request);
}