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
045  @Override
046  public void activateOptions() {
047    synchronized (this) {
048      if (maxEvents > 0) {
049        tail = new LinkedList<LoggingEvent>();
050      }
051      setFile(new File(this.containerLogDir, "syslog").toString());
052      setAppend(true);
053      super.activateOptions();
054    }
055  }
056  
057  @Override
058  public void append(LoggingEvent event) {
059    synchronized (this) {
060      if (tail == null) {
061        super.append(event);
062      } else {
063        if (tail.size() >= maxEvents) {
064          tail.remove();
065        }
066        tail.add(event);
067      }
068    }
069  }
070  
071  @Override
072  public void flush() {
073    if (qw != null) {
074      qw.flush();
075    }
076  }
077
078  @Override
079  public synchronized void close() {
080    if (tail != null) {
081      for(LoggingEvent event: tail) {
082        super.append(event);
083      }
084    }
085    super.close();
086  }
087
088  /**
089   * Getter/Setter methods for log4j.
090   */
091  
092  public String getContainerLogDir() {
093    return this.containerLogDir;
094  }
095
096  public void setContainerLogDir(String containerLogDir) {
097    this.containerLogDir = containerLogDir;
098  }
099
100  private static final int EVENT_SIZE = 100;
101  
102  public long getTotalLogFileSize() {
103    return maxEvents * EVENT_SIZE;
104  }
105
106  public void setTotalLogFileSize(long logSize) {
107    maxEvents = (int) logSize / EVENT_SIZE;
108  }
109}