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DailyRollingFileAppender.javaAPI DocApache log4j 1.2.1513976Sat Aug 25 00:09:42 BST 2007org.apache.log4j

DailyRollingFileAppender

public class DailyRollingFileAppender extends FileAppender
DailyRollingFileAppender extends {@link FileAppender} so that the underlying file is rolled over at a user chosen frequency.

The rolling schedule is specified by the DatePattern option. This pattern should follow the {@link SimpleDateFormat} conventions. In particular, you must escape literal text within a pair of single quotes. A formatted version of the date pattern is used as the suffix for the rolled file name.

For example, if the File option is set to /foo/bar.log and the DatePattern set to '.'yyyy-MM-dd, on 2001-02-16 at midnight, the logging file /foo/bar.log will be copied to /foo/bar.log.2001-02-16 and logging for 2001-02-17 will continue in /foo/bar.log until it rolls over the next day.

Is is possible to specify monthly, weekly, half-daily, daily, hourly, or minutely rollover schedules.

DatePattern Rollover schedule Example
'.'yyyy-MM Rollover at the beginning of each month At midnight of May 31st, 2002 /foo/bar.log will be copied to /foo/bar.log.2002-05. Logging for the month of June will be output to /foo/bar.log until it is also rolled over the next month.
'.'yyyy-ww Rollover at the first day of each week. The first day of the week depends on the locale. Assuming the first day of the week is Sunday, on Saturday midnight, June 9th 2002, the file /foo/bar.log will be copied to /foo/bar.log.2002-23. Logging for the 24th week of 2002 will be output to /foo/bar.log until it is rolled over the next week.
'.'yyyy-MM-dd Rollover at midnight each day. At midnight, on March 8th, 2002, /foo/bar.log will be copied to /foo/bar.log.2002-03-08. Logging for the 9th day of March will be output to /foo/bar.log until it is rolled over the next day.
'.'yyyy-MM-dd-a Rollover at midnight and midday of each day. At noon, on March 9th, 2002, /foo/bar.log will be copied to /foo/bar.log.2002-03-09-AM. Logging for the afternoon of the 9th will be output to /foo/bar.log until it is rolled over at midnight.
'.'yyyy-MM-dd-HH Rollover at the top of every hour. At approximately 11:00.000 o'clock on March 9th, 2002, /foo/bar.log will be copied to /foo/bar.log.2002-03-09-10. Logging for the 11th hour of the 9th of March will be output to /foo/bar.log until it is rolled over at the beginning of the next hour.
'.'yyyy-MM-dd-HH-mm Rollover at the beginning of every minute. At approximately 11:23,000, on March 9th, 2001, /foo/bar.log will be copied to /foo/bar.log.2001-03-09-10-22. Logging for the minute of 11:23 (9th of March) will be output to /foo/bar.log until it is rolled over the next minute.

Do not use the colon ":" character in anywhere in the DatePattern option. The text before the colon is interpeted as the protocol specificaion of a URL which is probably not what you want.

author
Eirik Lygre
author
Ceki Gülcü

Fields Summary
static final int
TOP_OF_TROUBLE
static final int
TOP_OF_MINUTE
static final int
TOP_OF_HOUR
static final int
HALF_DAY
static final int
TOP_OF_DAY
static final int
TOP_OF_WEEK
static final int
TOP_OF_MONTH
private String
datePattern
The date pattern. By default, the pattern is set to "'.'yyyy-MM-dd" meaning daily rollover.
private String
scheduledFilename
The log file will be renamed to the value of the scheduledFilename variable when the next interval is entered. For example, if the rollover period is one hour, the log file will be renamed to the value of "scheduledFilename" at the beginning of the next hour. The precise time when a rollover occurs depends on logging activity.
private long
nextCheck
The next time we estimate a rollover should occur.
Date
now
SimpleDateFormat
sdf
RollingCalendar
rc
int
checkPeriod
static final TimeZone
gmtTimeZone
Constructors Summary
public DailyRollingFileAppender()
The default constructor does nothing.
public DailyRollingFileAppender(Layout layout, String filename, String datePattern)
Instantiate a DailyRollingFileAppender and open the file designated by filename. The opened filename will become the ouput destination for this appender.

    super(layout, filename, true);
    this.datePattern = datePattern;
    activateOptions();
Methods Summary
public voidactivateOptions()

    super.activateOptions();
    if(datePattern != null && fileName != null) {
      now.setTime(System.currentTimeMillis());
      sdf = new SimpleDateFormat(datePattern);
      int type = computeCheckPeriod();
      printPeriodicity(type);
      rc.setType(type);
      File file = new File(fileName);
      scheduledFilename = fileName+sdf.format(new Date(file.lastModified()));

    } else {
      LogLog.error("Either File or DatePattern options are not set for appender ["
		   +name+"].");
    }
intcomputeCheckPeriod()

    RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone, Locale.ENGLISH);
    // set sate to 1970-01-01 00:00:00 GMT
    Date epoch = new Date(0);
    if(datePattern != null) {
      for(int i = TOP_OF_MINUTE; i <= TOP_OF_MONTH; i++) {
	SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern);
	simpleDateFormat.setTimeZone(gmtTimeZone); // do all date formatting in GMT
	String r0 = simpleDateFormat.format(epoch);
	rollingCalendar.setType(i);
	Date next = new Date(rollingCalendar.getNextCheckMillis(epoch));
	String r1 =  simpleDateFormat.format(next);
	//System.out.println("Type = "+i+", r0 = "+r0+", r1 = "+r1);
	if(r0 != null && r1 != null && !r0.equals(r1)) {
	  return i;
	}
      }
    }
    return TOP_OF_TROUBLE; // Deliberately head for trouble...
public java.lang.StringgetDatePattern()
Returns the value of the DatePattern option.

    return datePattern;
voidprintPeriodicity(int type)

    switch(type) {
    case TOP_OF_MINUTE:
      LogLog.debug("Appender ["+name+"] to be rolled every minute.");
      break;
    case TOP_OF_HOUR:
      LogLog.debug("Appender ["+name
		   +"] to be rolled on top of every hour.");
      break;
    case HALF_DAY:
      LogLog.debug("Appender ["+name
		   +"] to be rolled at midday and midnight.");
      break;
    case TOP_OF_DAY:
      LogLog.debug("Appender ["+name
		   +"] to be rolled at midnight.");
      break;
    case TOP_OF_WEEK:
      LogLog.debug("Appender ["+name
		   +"] to be rolled at start of week.");
      break;
    case TOP_OF_MONTH:
      LogLog.debug("Appender ["+name
		   +"] to be rolled at start of every month.");
      break;
    default:
      LogLog.warn("Unknown periodicity for appender ["+name+"].");
    }
voidrollOver()
Rollover the current file to a new file.


    /* Compute filename, but only if datePattern is specified */
    if (datePattern == null) {
      errorHandler.error("Missing DatePattern option in rollOver().");
      return;
    }

    String datedFilename = fileName+sdf.format(now);
    // It is too early to roll over because we are still within the
    // bounds of the current interval. Rollover will occur once the
    // next interval is reached.
    if (scheduledFilename.equals(datedFilename)) {
      return;
    }

    // close current file, and rename it to datedFilename
    this.closeFile();

    File target  = new File(scheduledFilename);
    if (target.exists()) {
      target.delete();
    }

    File file = new File(fileName);
    boolean result = file.renameTo(target);
    if(result) {
      LogLog.debug(fileName +" -> "+ scheduledFilename);
    } else {
      LogLog.error("Failed to rename ["+fileName+"] to ["+scheduledFilename+"].");
    }

    try {
      // This will also close the file. This is OK since multiple
      // close operations are safe.
      this.setFile(fileName, false, this.bufferedIO, this.bufferSize);
    }
    catch(IOException e) {
      errorHandler.error("setFile("+fileName+", false) call failed.");
    }
    scheduledFilename = datedFilename;
public voidsetDatePattern(java.lang.String pattern)
The DatePattern takes a string in the same format as expected by {@link SimpleDateFormat}. This options determines the rollover schedule.

    datePattern = pattern;
protected voidsubAppend(org.apache.log4j.spi.LoggingEvent event)
This method differentiates DailyRollingFileAppender from its super class.

Before actually logging, this method will check whether it is time to do a rollover. If it is, it will schedule the next rollover time and then rollover.

    long n = System.currentTimeMillis();
    if (n >= nextCheck) {
      now.setTime(n);
      nextCheck = rc.getNextCheckMillis(now);
      try {
	rollOver();
      }
      catch(IOException ioe) {
	LogLog.error("rollOver() failed.", ioe);
      }
    }
    super.subAppend(event);