LibrarySchedulerClient.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.scheduler.client;

import com.twitter.heron.common.basics.SysUtils;
import com.twitter.heron.proto.scheduler.Scheduler;
import com.twitter.heron.spi.common.Config;
import com.twitter.heron.spi.scheduler.IScheduler;

/**
 * This class manages topology by invoking IScheduler's interface directly as a library.
 */
public class LibrarySchedulerClient implements ISchedulerClient {
  private final Config config;
  private final Config runtime;
  private final IScheduler scheduler;

  public LibrarySchedulerClient(Config config, Config runtime, IScheduler scheduler) {
    this.config = config;
    this.runtime = runtime;
    this.scheduler = scheduler;
  }

  @Override
  public boolean restartTopology(Scheduler.RestartTopologyRequest restartTopologyRequest) {
    boolean ret = false;

    try {
      scheduler.initialize(config, runtime);
      ret = scheduler.onRestart(restartTopologyRequest);
    } finally {
      SysUtils.closeIgnoringExceptions(scheduler);
    }

    return ret;
  }

  @Override
  public boolean killTopology(Scheduler.KillTopologyRequest killTopologyRequest) {
    boolean ret = false;

    try {
      scheduler.initialize(config, runtime);
      ret = scheduler.onKill(killTopologyRequest);
    } finally {
      SysUtils.closeIgnoringExceptions(scheduler);
    }

    return ret;
  }

  @Override
  public boolean updateTopology(Scheduler.UpdateTopologyRequest updateTopologyRequest) {
    boolean ret = false;

    try {
      scheduler.initialize(config, runtime);
      ret = scheduler.onUpdate(updateTopologyRequest);
    } finally {
      SysUtils.closeIgnoringExceptions(scheduler);
    }

    return ret;
  }

  // TODO(mfu): Use JAVA8's lambda feature providing a method for all commands in SchedulerUtils
  // TODO(mfu): boolean invokeSchedulerAsLibrary(String commandName, Function invoker);
}