/**
    *
    * 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.monitoring;
  
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.util.Map;
  
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.executor.ExecutorService;
  import org.apache.hadoop.hbase.executor.ExecutorService.ExecutorStatus;
  import org.apache.hadoop.hbase.util.VersionInfo;
  
  @InterfaceAudience.Private
  public abstract class StateDumpServlet extends HttpServlet {
    static final long DEFAULT_TAIL_KB = 100;
    private static final long serialVersionUID = 1L;
  
    protected void dumpVersionInfo(PrintWriter out) {
      VersionInfo.writeTo(out);
  
      out.println("Hadoop " + org.apache.hadoop.util.VersionInfo.getVersion());
      out.println("Source code repository " + org.apache.hadoop.util.VersionInfo.getUrl()
        + " revision=" + org.apache.hadoop.util.VersionInfo.getRevision());
      out.println("Compiled by " + org.apache.hadoop.util.VersionInfo.getUser() +
          " on " + org.apache.hadoop.util.VersionInfo.getDate());
    }
  
    protected boolean isShowQueueDump(Configuration conf){
      return conf.getBoolean("hbase.regionserver.servlet.show.queuedump", true);
    }
  
    protected long getTailKbParam(HttpServletRequest request) {
      String param = request.getParameter("tailkb");
      if (param == null) {
        return DEFAULT_TAIL_KB;
      }
      return Long.parseLong(param);
    }
  
    protected void dumpExecutors(ExecutorService service, PrintWriter out)
        throws IOException {
      if (service == null) {
        out.println("ExecutorService is not initialized");
        return;
      }
  
      Map<String, ExecutorStatus> statuses = service.getAllExecutorStatuses();
      for (ExecutorStatus status : statuses.values()) {
        status.dumpTo(out, "  ");
      }
    }
  }