/*
    * 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.hadoop.hbase.http;
  
  import java.io.File;
  import java.io.IOException;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.mortbay.jetty.servlet.DefaultServlet;
  
  /**
   * Servlet to serve files generated by {@link ProfileServlet}
   */
  public class ProfileOutputServlet extends DefaultServlet {
    private static final long serialVersionUID = 1L;
    private static final Log LOG = LogFactory.getLog(ProfileOutputServlet.class);
    private static final int REFRESH_PERIOD = 2;
  
    @Override
    protected void doGet(final HttpServletRequest req, final HttpServletResponse resp)
      throws ServletException, IOException {
      String absoluteDiskPath = getServletContext().getRealPath(req.getPathInfo());
      File requestedFile = new File(absoluteDiskPath);
      // async-profiler version 1.4 writes 'Started [cpu] profiling' to output file when profiler is
      // running which gets replaced by final output. If final output is not ready yet, the file size
      // will be <100 bytes (in all modes).
      if (requestedFile.length() < 100) {
        LOG.info(requestedFile  + " is incomplete. Sending auto-refresh header.");
        resp.setHeader("Refresh", REFRESH_PERIOD + "," + req.getRequestURI());
        resp.getWriter().write("This page will be auto-refreshed every " + REFRESH_PERIOD +
          " seconds until the output file is ready.");
      } else {
        super.doGet(req, resp);
      }
    }
  }