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Server functionality for HBase

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/*
 * 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);
    }
  }
}