001/**
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *     http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 */
019package org.apache.hadoop.hbase.monitoring;
020
021import java.io.BufferedReader;
022import java.io.File;
023import java.io.FileInputStream;
024import java.io.IOException;
025import java.io.InputStreamReader;
026import java.io.PrintWriter;
027import java.nio.channels.FileChannel;
028import java.util.Enumeration;
029import java.util.Set;
030
031import org.apache.yetus.audience.InterfaceAudience;
032import org.apache.hadoop.io.IOUtils;
033import org.apache.log4j.Appender;
034import org.apache.log4j.FileAppender;
035import org.apache.log4j.Logger;
036
037import org.apache.hbase.thirdparty.com.google.common.collect.Sets;
038
039/**
040 * Utility functions for reading the log4j logs that are
041 * being written by HBase.
042 */
043@InterfaceAudience.Private
044public abstract class LogMonitoring {
045  public static Set<File> getActiveLogFiles() throws IOException {
046    Set<File> ret = Sets.newHashSet();
047    Appender a;
048    @SuppressWarnings("unchecked")
049    Enumeration<Appender> e = Logger.getRootLogger().getAllAppenders();
050    while (e.hasMoreElements()) {
051      a = e.nextElement();
052      if (a instanceof FileAppender) {
053        FileAppender fa = (FileAppender) a;
054        String filename = fa.getFile();
055        ret.add(new File(filename));
056      }
057    }
058    return ret;
059  }
060  
061
062  public static void dumpTailOfLogs(
063      PrintWriter out, long tailKb) throws IOException {
064    Set<File> logs = LogMonitoring.getActiveLogFiles();
065    for (File f : logs) {
066      out.println("+++++++++++++++++++++++++++++++");
067      out.println(f.getAbsolutePath());
068      out.println("+++++++++++++++++++++++++++++++");
069      try {
070        dumpTailOfLog(f, out, tailKb);
071      } catch (IOException ioe) {
072        out.println("Unable to dump log at " + f);
073        ioe.printStackTrace(out);
074      }
075      out.println("\n\n");
076    }
077  }
078
079  private static void dumpTailOfLog(File f, PrintWriter out, long tailKb)
080      throws IOException {
081    FileInputStream fis = new FileInputStream(f);
082    BufferedReader r = null;
083    try {
084      FileChannel channel = fis.getChannel();
085      channel.position(Math.max(0, channel.size() - tailKb*1024));
086      r = new BufferedReader(new InputStreamReader(fis));
087      r.readLine(); // skip the first partial line
088      String line;
089      while ((line = r.readLine()) != null) {
090        out.println(line);
091      }
092    } finally {
093      if (r != null) IOUtils.closeStream(r);
094      IOUtils.closeStream(fis);
095    }
096  }
097}