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RollingFileAppender.javaAPI DocApache log4j 1.2.158240Sat Aug 25 00:09:42 BST 2007org.apache.log4j

RollingFileAppender

public class RollingFileAppender extends FileAppender
RollingFileAppender extends FileAppender to backup the log files when they reach a certain size.
author
Heinz Richter
author
Ceki Gülcü

Fields Summary
protected long
maxFileSize
The default maximum file size is 10MB.
protected int
maxBackupIndex
There is one backup file by default.
private long
nextRollover
Constructors Summary
public RollingFileAppender()
The default constructor simply calls its {@link FileAppender#FileAppender parents constructor}.


                      
  
   
    super();
public RollingFileAppender(Layout layout, String filename, boolean append)
Instantiate a RollingFileAppender and open the file designated by filename. The opened filename will become the ouput destination for this appender.

If the append parameter is true, the file will be appended to. Otherwise, the file desginated by filename will be truncated before being opened.

    super(layout, filename, append);
public RollingFileAppender(Layout layout, String filename)
Instantiate a FileAppender and open the file designated by filename. The opened filename will become the output destination for this appender.

The file will be appended to.

    super(layout, filename);
Methods Summary
public intgetMaxBackupIndex()
Returns the value of the MaxBackupIndex option.

    return maxBackupIndex;
public longgetMaximumFileSize()
Get the maximum size that the output file is allowed to reach before being rolled over to backup files.

since
1.1

    return maxFileSize;
public voidrollOver()
Implements the usual roll over behaviour.

If MaxBackupIndex is positive, then files {File.1, ..., File.MaxBackupIndex -1} are renamed to {File.2, ..., File.MaxBackupIndex}. Moreover, File is renamed File.1 and closed. A new File is created to receive further log output.

If MaxBackupIndex is equal to zero, then the File is truncated with no backup files created.

    File target;
    File file;

    if (qw != null) {
        long size = ((CountingQuietWriter) qw).getCount();
        LogLog.debug("rolling over count=" + size);
        //   if operation fails, do not roll again until
        //      maxFileSize more bytes are written
        nextRollover = size + maxFileSize;
    }
    LogLog.debug("maxBackupIndex="+maxBackupIndex);

    boolean renameSucceeded = true;
    // If maxBackups <= 0, then there is no file renaming to be done.
    if(maxBackupIndex > 0) {
      // Delete the oldest file, to keep Windows happy.
      file = new File(fileName + '." + maxBackupIndex);
      if (file.exists())
       renameSucceeded = file.delete();

      // Map {(maxBackupIndex - 1), ..., 2, 1} to {maxBackupIndex, ..., 3, 2}
      for (int i = maxBackupIndex - 1; i >= 1 && renameSucceeded; i--) {
	file = new File(fileName + "." + i);
	if (file.exists()) {
	  target = new File(fileName + '." + (i + 1));
	  LogLog.debug("Renaming file " + file + " to " + target);
	  renameSucceeded = file.renameTo(target);
	}
      }

    if(renameSucceeded) {
      // Rename fileName to fileName.1
      target = new File(fileName + "." + 1);

      this.closeFile(); // keep windows happy.

      file = new File(fileName);
      LogLog.debug("Renaming file " + file + " to " + target);
      renameSucceeded = file.renameTo(target);
      //
      //   if file rename failed, reopen file with append = true
      //
      if (!renameSucceeded) {
          try {
            this.setFile(fileName, true, bufferedIO, bufferSize);
          }
          catch(IOException e) {
            LogLog.error("setFile("+fileName+", true) call failed.", e);
          }
      }
    }
    }

    //
    //   if all renames were successful, then
    //
    if (renameSucceeded) {
    try {
      // This will also close the file. This is OK since multiple
      // close operations are safe.
      this.setFile(fileName, false, bufferedIO, bufferSize);
      nextRollover = 0;
    }
    catch(IOException e) {
      LogLog.error("setFile("+fileName+", false) call failed.", e);
    }
    }
public synchronized voidsetFile(java.lang.String fileName, boolean append, boolean bufferedIO, int bufferSize)

    super.setFile(fileName, append, this.bufferedIO, this.bufferSize);
    if(append) {
      File f = new File(fileName);
      ((CountingQuietWriter) qw).setCount(f.length());
    }
public voidsetMaxBackupIndex(int maxBackups)
Set the maximum number of backup files to keep around.

The MaxBackupIndex option determines how many backup files are kept before the oldest is erased. This option takes a positive integer value. If set to zero, then there will be no backup files and the log file will be truncated when it reaches MaxFileSize.

    this.maxBackupIndex = maxBackups;
public voidsetMaxFileSize(java.lang.String value)
Set the maximum size that the output file is allowed to reach before being rolled over to backup files.

In configuration files, the MaxFileSize option takes an long integer in the range 0 - 2^63. You can specify the value with the suffixes "KB", "MB" or "GB" so that the integer is interpreted being expressed respectively in kilobytes, megabytes or gigabytes. For example, the value "10KB" will be interpreted as 10240.

    maxFileSize = OptionConverter.toFileSize(value, maxFileSize + 1);
public voidsetMaximumFileSize(long maxFileSize)
Set the maximum size that the output file is allowed to reach before being rolled over to backup files.

This method is equivalent to {@link #setMaxFileSize} except that it is required for differentiating the setter taking a long argument from the setter taking a String argument by the JavaBeans {@link java.beans.Introspector Introspector}.

see
#setMaxFileSize(String)

    this.maxFileSize = maxFileSize;
protected voidsetQWForFiles(java.io.Writer writer)

     this.qw = new CountingQuietWriter(writer, errorHandler);
protected voidsubAppend(org.apache.log4j.spi.LoggingEvent event)
This method differentiates RollingFileAppender from its super class.

since
0.9.0

    super.subAppend(event);
    if(fileName != null && qw != null) {
        long size = ((CountingQuietWriter) qw).getCount();
        if (size >= maxFileSize && size >= nextRollover) {
            rollOver();
        }
    }