HeartbeatServlet.java

/*
 * Copyright 2009 Google 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.google.jstestdriver;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * @author jeremiele@google.com (Jeremie Lenfant-Engelmann)
 */
public class HeartbeatServlet extends HttpServlet {

  private static final long TIMEOUT = 15000L; // 15 seconds
  private final CapturedBrowsers capturedBrowsers;
  private final Time time;

  public HeartbeatServlet(CapturedBrowsers capturedBrowsers, Time time) {
    this.capturedBrowsers = capturedBrowsers;
    this.time = time;
  }

  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    PrintWriter writer = resp.getWriter();
    String id = req.getParameter("id");
    SlaveBrowser browser = capturedBrowsers.getBrowser(id);

    if ((time.now().getMillis() - browser.getLastHeartBeat().getMillis()) > TIMEOUT) {
      capturedBrowsers.removeSlave(id);
      writer.write("DEAD");
    } else {
      writer.write("OK");
    }
    writer.flush();
  }

  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    SlaveBrowser browser = capturedBrowsers.getBrowser(req.getParameter("id"));

    if (browser != null) {
      browser.heartBeat();
    }
    resp.getWriter().flush();
  }
}