SchedulerServer.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.server;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import com.sun.net.httpserver.HttpServer;

import com.twitter.heron.spi.common.Config;
import com.twitter.heron.spi.scheduler.IScheduler;
import com.twitter.heron.spi.utils.NetworkUtils;

public class SchedulerServer {

  // initialize the various URL end points
  private static final String KILL_REQUEST_CONTEXT = "/kill";
  private static final String RESTART_REQUEST_CONTEXT = "/restart";
  private static final String UPDATE_REQUEST_CONTEXT = "/update";

  private static final int SERVER_BACK_LOG = 0;

  private final HttpServer schedulerServer;
  private final IScheduler scheduler;
  private final ExecutorService executorService = Executors.newSingleThreadExecutor();

  public SchedulerServer(Config runtime, IScheduler scheduler, int port)
      throws IOException {

    this.scheduler = scheduler;
    this.schedulerServer = createServer(port, executorService);

    // associate handlers with the URL service end points
    this.schedulerServer.createContext(KILL_REQUEST_CONTEXT,
        new ExceptionalRequestHandler(new KillRequestHandler(scheduler), runtime, scheduler));

    this.schedulerServer.createContext(RESTART_REQUEST_CONTEXT,
        new ExceptionalRequestHandler(new RestartRequestHandler(scheduler), runtime, scheduler));

    this.schedulerServer.createContext(UPDATE_REQUEST_CONTEXT,
        new ExceptionalRequestHandler(new UpdateRequestHandler(scheduler), runtime, scheduler));
  }

  public void start() {
    schedulerServer.start();
  }

  public void stop() {
    schedulerServer.stop(0);
    scheduler.close();

    // Stopping the server will not shut down the Executor
    // We have to shut it down explicitly
    executorService.shutdownNow();
  }

  public String getHost() {
    return NetworkUtils.getHostName();
  }

  public int getPort() {
    return schedulerServer.getAddress().getPort();
  }

  protected HttpServer createServer(int port, Executor executor) throws IOException {
    HttpServer server = HttpServer.create(new InetSocketAddress(port), SERVER_BACK_LOG);
    server.setExecutor(executor);
    return server;
  }
}