001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.yarn;
020
021import java.io.File;
022import java.io.Flushable;
023import java.util.LinkedList;
024import java.util.Queue;
025
026import org.apache.hadoop.classification.InterfaceAudience.Public;
027import org.apache.hadoop.classification.InterfaceStability.Unstable;
028import org.apache.log4j.FileAppender;
029import org.apache.log4j.spi.LoggingEvent;
030
031/**
032 * A simple log4j-appender for container's logs.
033 * 
034 */
035@Public
036@Unstable
037public class ContainerLogAppender extends FileAppender
038  implements Flushable
039{
040  private String containerLogDir;
041  //so that log4j can configure it from the configuration(log4j.properties). 
042  private int maxEvents;
043  private Queue<LoggingEvent> tail = null;
044  private boolean closing = false;
045
046  @Override
047  public void activateOptions() {
048    synchronized (this) {
049      if (maxEvents > 0) {
050        tail = new LinkedList<LoggingEvent>();
051      }
052      setFile(new File(this.containerLogDir, "syslog").toString());
053      setAppend(true);
054      super.activateOptions();
055    }
056  }
057  
058  @Override
059  public void append(LoggingEvent event) {
060    synchronized (this) {
061      if (closing) { // When closing drop any new/transitive CLA appending
062        return;
063      }
064      if (tail == null) {
065        super.append(event);
066      } else {
067        if (tail.size() >= maxEvents) {
068          tail.remove();
069        }
070        tail.add(event);
071      }
072    }
073  }
074  
075  @Override
076  public void flush() {
077    if (qw != null) {
078      qw.flush();
079    }
080  }
081
082  @Override
083  public synchronized void close() {
084    closing = true;
085    if (tail != null) {
086      for (LoggingEvent event : tail) {
087        super.append(event);
088      }
089    }
090    super.close();
091  }
092
093  /**
094   * Getter/Setter methods for log4j.
095   */
096  
097  public String getContainerLogDir() {
098    return this.containerLogDir;
099  }
100
101  public void setContainerLogDir(String containerLogDir) {
102    this.containerLogDir = containerLogDir;
103  }
104
105  private static final int EVENT_SIZE = 100;
106  
107  public long getTotalLogFileSize() {
108    return maxEvents * EVENT_SIZE;
109  }
110
111  public void setTotalLogFileSize(long logSize) {
112    maxEvents = (int) logSize / EVENT_SIZE;
113  }
114}