How to configure a log4j file appender which rolls the log file every 15 minutes

Question

I understand that i can use a DailyRollingFileAppender to roll the log file every month, day, half-day, hour or minute. But how can i configure log4j to roll the log file every 15 minutes.

If this is not possible by configuration, please suggest/direct me on how to extend log4j's file appender to achieve this.

Thanks and Regards.

Answer 1

The Javadoc for DailyRollingFileAppender in Log4J indicates that the time-based rolling only occurs on unit-based rollovers (day, week, month, etc.). That would mean the closest you could get with that pattern is '.'yyyy-MM-dd-HH-mm, which would roll over every minute.

My recommendations would be to do one of the following:

• Since you're running on a fixed interval, write a custom FileAppender that uses logic borrowed from DailyRollingFileAppender to make the computation
• If you have some flexibility, switch from Log4J to LOGBack, and write a custom RollingPolicy that uses logic borrowed from the LOGBack time calculations (which will be very similar to the ones in Log4J)

By the way, if you choose the latter, I'd recommend that you consider coding to the SLF4J API, and use LOGBack (or Log4J) as the underlying implementation.

Answer 2

I created this appender. It is copy of DailyRollingFileAppender just with few changes. First I remove type HALF_DAY (here it doesnt make any sence) and add one variable timeInterval. Now this log to the file every x something depends on datePatter. For examle:

this log every 2 minutes

log4j.appender.APP=path.to.class.CustomRollingFileAppender
log4j.appender.APP.DatePattern=.yyyy-MM-dd-HH-mm
log4j.appender.APP.TimeInterval=2

this log every 3 hours

log4j.appender.APP=path.to.class.CustomRollingFileAppender
log4j.appender.APP.DatePattern=.yyyy-MM-dd-HH
log4j.appender.APP.TimeInterval=3

CustomRollingFileAppender :

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;

import org.apache.log4j.FileAppender;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

/**
 * DailyRollingFileAppender extends {@link FileAppender} so that the underlying file is rolled over at a user chosen
 * frequency.
 * 
 * <p>
 * The rolling schedule is specified by the <b>DatePattern</b> option. This pattern should follow the
 * {@link SimpleDateFormat} conventions. In particular, you <em>must</em> 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.
 * 
 * <p>
 * For example, if the <b>File</b> option is set to <code>/foo/bar.log</code> and the <b>DatePattern</b> set to
 * <code>'.'yyyy-MM-dd</code>, on 2001-02-16 at midnight, the logging file <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2001-02-16</code> and logging for 2001-02-17 will continue in <code>/foo/bar.log</code> until it
 * rolls over the next day.
 * 
 * <p>
 * Is is possible to specify monthly, weekly, half-daily, daily, hourly, or minutely rollover schedules.
 * 
 * <p>
 * <table border="1" cellpadding="2">
 * <tr>
 * <th>DatePattern</th>
 * <th>Rollover schedule</th>
 * <th>Example</th>
 * 
 * <tr>
 * <td><code>'.'yyyy-MM</code>
 * <td>Rollover at the beginning of each month</td>
 * 
 * <td>At midnight of May 31st, 2002 <code>/foo/bar.log</code> will be copied to <code>/foo/bar.log.2002-05</code>.
 * Logging for the month of June will be output to <code>/foo/bar.log</code> until it is also rolled over the next
 * month.
 * 
 * <tr>
 * <td><code>'.'yyyy-ww</code>
 * 
 * <td>Rollover at the first day of each week. The first day of the week depends on the locale.</td>
 * 
 * <td>Assuming the first day of the week is Sunday, on Saturday midnight, June 9th 2002, the file <i>/foo/bar.log</i>
 * will be copied to <i>/foo/bar.log.2002-23</i>. Logging for the 24th week of 2002 will be output to
 * <code>/foo/bar.log</code> until it is rolled over the next week.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd</code>
 * 
 * <td>Rollover at midnight each day.</td>
 * 
 * <td>At midnight, on March 8th, 2002, <code>/foo/bar.log</code> will be copied to <code>/foo/bar.log.2002-03-08</code>
 * . Logging for the 9th day of March will be output to <code>/foo/bar.log</code> until it is rolled over the next day.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-a</code>
 * 
 * <td>Rollover at midnight and midday of each day.</td>
 * 
 * <td>At noon, on March 9th, 2002, <code>/foo/bar.log</code> will be copied to <code>/foo/bar.log.2002-03-09-AM</code>.
 * Logging for the afternoon of the 9th will be output to <code>/foo/bar.log</code> until it is rolled over at midnight.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH</code>
 * 
 * <td>Rollover at the top of every hour.</td>
 * 
 * <td>At approximately 11:00.000 o'clock on March 9th, 2002, <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-03-09-10</code>. Logging for the 11th hour of the 9th of March will be output to
 * <code>/foo/bar.log</code> until it is rolled over at the beginning of the next hour.
 * 
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH-mm</code>
 * 
 * <td>Rollover at the beginning of every minute.</td>
 * 
 * <td>At approximately 11:23,000, on March 9th, 2001, <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2001-03-09-10-22</code>. Logging for the minute of 11:23 (9th of March) will be output to
 * <code>/foo/bar.log</code> until it is rolled over the next minute.
 * 
 * </table>
 * 
 * <p>
 * Do not use the colon ":" character in anywhere in the <b>DatePattern</b> 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 G&uuml;lc&uuml;
 */
public class CustomRollingFileAppender extends FileAppender {

    // The code assumes that the following constants are in a increasing
    // sequence.
    static final int TOP_OF_TROUBLE = -1;
    static final int TOP_OF_MINUTE = 0;
    static final int TOP_OF_HOUR = 1;
    static final int TOP_OF_DAY = 2;
    static final int TOP_OF_WEEK = 3;
    static final int TOP_OF_MONTH = 4;

    /**
     * The date pattern. By default, the pattern is set to "'.'yyyy-MM-dd" meaning daily rollover.
     */
    private String datePattern = "'.'yyyy-MM-dd";

    private int timeInterval = 1;

    /**
     * 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 String scheduledFilename;

    /**
     * The next time we estimate a rollover should occur.
     */
    private long nextCheck = System.currentTimeMillis() - 1;

    Date now = new Date();

    SimpleDateFormat sdf;

    RollingCalendar rc = new RollingCalendar();

    int checkPeriod = TOP_OF_TROUBLE;

    // The gmtTimeZone is used only in computeCheckPeriod() method.
    static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");

    /**
     * The default constructor does nothing.
     */
    public CustomRollingFileAppender() {
    }

    /**
     * Instantiate a <code>DailyRollingFileAppender</code> and open the file designated by <code>filename</code>. The
     * opened filename will become the ouput destination for this appender.
     */
    public CustomRollingFileAppender(Layout layout, String filename, String datePattern) throws IOException {
        super(layout, filename, true);
        this.datePattern = datePattern;
        activateOptions();
    }

    /**
     * The <b>DatePattern</b> takes a string in the same format as expected by {@link SimpleDateFormat}. This options
     * determines the rollover schedule.
     */
    public void setDatePattern(String pattern) {
        datePattern = pattern;
    }

    /** Returns the value of the <b>DatePattern</b> option. */
    public String getDatePattern() {
        return datePattern;
    }

    public void activateOptions() {
        super.activateOptions();
        if (datePattern != null && fileName != null) {
            now.setTime(System.currentTimeMillis());
            sdf = new SimpleDateFormat(datePattern);
            int type = computeCheckPeriod();
            printPeriodicity(type);
            rc.setType(type);
            rc.setTimeInterval(timeInterval);
            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 + "].");
        }
    }

    void printPeriodicity(int type) {
        switch (type) {
        case TOP_OF_MINUTE:
            LogLog.debug("Appender [" + name + "] to be rolled every " + timeInterval + " minutes.");
            break;
        case TOP_OF_HOUR:
            LogLog.debug("Appender [" + name + "] to be rolled every " + timeInterval + " hours.");
            break;
        case TOP_OF_DAY:
            LogLog.debug("Appender [" + name + "] to be rolled every " + timeInterval + " days.");
            break;
        case TOP_OF_WEEK:
            LogLog.debug("Appender [" + name + "] to be rolled every " + timeInterval + " weeks.");
            break;
        case TOP_OF_MONTH:
            LogLog.debug("Appender [" + name + "] to be rolled every " + timeInterval + " months.");
            break;
        default:
            LogLog.warn("Unknown periodicity for appender [" + name + "].");
        }
    }

    // This method computes the roll over period by looping over the
    // periods, starting with the shortest, and stopping when the r0 is
    // different from from r1, where r0 is the epoch formatted according
    // the datePattern (supplied by the user) and r1 is the
    // epoch+nextMillis(i) formatted according to datePattern. All date
    // formatting is done in GMT and not local format because the test
    // logic is based on comparisons relative to 1970-01-01 00:00:00
    // GMT (the epoch).

    int computeCheckPeriod() {
        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...
    }

    /**
     * Rollover the current file to a new file.
     */
    void rollOver() throws IOException {

        /* 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;
    }

    /**
     * This method differentiates DailyRollingFileAppender from its super class.
     * 
     * <p>
     * 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.
     * */
    protected void subAppend(LoggingEvent event) {
        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);
    }

    public int getTimeInterval() {
        return timeInterval;
    }

    public void setTimeInterval(int timeInterval) {
        this.timeInterval = timeInterval;
    }
}

/**
 * RollingCalendar is a helper class to DailyRollingFileAppender. Given a periodicity type and the current time, it
 * computes the start of the next interval.
 * */
class RollingCalendar extends GregorianCalendar {
    private static final long serialVersionUID = -3560331770601814177L;

    int type = CustomRollingFileAppender.TOP_OF_TROUBLE;

    int timeInterval = 1;

    RollingCalendar() {
        super();
    }

    public void setTimeInterval(int timeInterval) {
        this.timeInterval = timeInterval;
    }

    RollingCalendar(TimeZone tz, Locale locale) {
        super(tz, locale);
    }

    void setType(int type) {
        this.type = type;
    }

    public long getNextCheckMillis(Date now) {
        return getNextCheckDate(now).getTime();
    }

    public Date getNextCheckDate(Date now) {
        this.setTime(now);

        switch (type) {
        case CustomRollingFileAppender.TOP_OF_MINUTE:
            this.set(Calendar.SECOND, 0);
            this.set(Calendar.MILLISECOND, 0);
            this.add(Calendar.MINUTE, timeInterval);
            break;
        case CustomRollingFileAppender.TOP_OF_HOUR:
            this.set(Calendar.MINUTE, 0);
            this.set(Calendar.SECOND, 0);
            this.set(Calendar.MILLISECOND, 0);
            this.add(Calendar.HOUR_OF_DAY, timeInterval);
            break;
        case CustomRollingFileAppender.TOP_OF_DAY:
            this.set(Calendar.HOUR_OF_DAY, 0);
            this.set(Calendar.MINUTE, 0);
            this.set(Calendar.SECOND, 0);
            this.set(Calendar.MILLISECOND, 0);
            this.add(Calendar.DATE, timeInterval);
            break;
        case CustomRollingFileAppender.TOP_OF_WEEK:
            this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
            this.set(Calendar.HOUR_OF_DAY, 0);
            this.set(Calendar.MINUTE, 0);
            this.set(Calendar.SECOND, 0);
            this.set(Calendar.MILLISECOND, 0);
            this.add(Calendar.WEEK_OF_YEAR, timeInterval);
            break;
        case CustomRollingFileAppender.TOP_OF_MONTH:
            this.set(Calendar.DATE, 1);
            this.set(Calendar.HOUR_OF_DAY, 0);
            this.set(Calendar.MINUTE, 0);
            this.set(Calendar.SECOND, 0);
            this.set(Calendar.MILLISECOND, 0);
            this.add(Calendar.MONTH, timeInterval);
            break;
        default:
            throw new IllegalStateException("Unknown periodicity type.");
        }
        return getTime();
    }
}

Answer 3

Here is code I use for Hourly. You can alter it for every 15 minutes - see method nextCalendar(). This code is based on DatedFileAppender.

package com.stackoverflow.log4j;

import java.io.File;
import java.util.Calendar;
import java.util.Date;

import org.apache.log4j.FileAppender;
import org.apache.log4j.spi.LoggingEvent;

/**
 * Based on biz.minaret.log4j.DatedFileAppender, 
 * decompiled with JAD,
 * revised to use optional hours.
 */
public class DistinctDailyFileAppender extends FileAppender {

public static final String DEFAULT_DIRECTORY = "logs";
public static final String DEFAULT_SUFFIX = ".txt";
public static final String DEFAULT_PREFIX = "";

private String directory = DEFAULT_DIRECTORY;
private String prefix = DEFAULT_PREFIX;
private String suffix = DEFAULT_SUFFIX;
private File currentPath = null;
private Calendar currentCalendar = null;
private long nextTime = 0l;
private boolean hourly = false;

/**
 * Constructor.
 */
public DistinctDailyFileAppender() {}

/**
 * This method is automatically called once by the system, 
 * immediately after all properties are set, prior to release.
 */
public void activateOptions() {

    currentPath = new File(directory);
    if (!currentPath.isAbsolute()) {        
        errorHandler.error("Directory failure for appender [" + name + "] : " + directory);
        return;
    }

    currentPath.mkdirs();

    // We can write; initialize calendar
    if (currentPath.canWrite()) {
        currentCalendar = Calendar.getInstance();
    } else {
        errorHandler.error("Cannot write for appender [" + name + "] : " + directory);
        return;
    }       
}

/**
 * This is called, synchronized by parent.
 */
public void append(LoggingEvent event) {

    if (layout == null) {
        errorHandler.error("No layout set for appender [" + name + "].");
        return;
    }

    if (currentCalendar == null) {
        errorHandler.error("Improper initialization for appender [" + name + "].");
        return;
    }

    long nowTime = System.currentTimeMillis();
    if (nowTime >= nextTime) {
        currentCalendar.setTime(new Date(nowTime));
        String timestamp = generateTimestamp(currentCalendar);
        nextCalendar(currentCalendar);
        nextTime = currentCalendar.getTime().getTime();
        File file = new File(currentPath, prefix + timestamp + suffix);
        fileName = file.getAbsolutePath();
        super.activateOptions();
    }

    if (super.qw == null) {

        errorHandler.error("No output stream or file set for the appender named [" + name + "].");
        return;

    } else {

        subAppend(event);
        return;

    }
}

protected String generateTimestamp(Calendar calendar) {

    int year = calendar.get(Calendar.YEAR);
    int month = calendar.get(Calendar.MONTH) + 1;
    int day = calendar.get(Calendar.DAY_OF_MONTH);
    int hour = calendar.get(Calendar.HOUR_OF_DAY);
    int minutes = calendar.get(Calendar.MINUTE);
    int seconds = calendar.get(Calendar.SECOND);

    StringBuffer buffer = new StringBuffer();

    if (year < 1000) {
        buffer.append('0');
        if (year < 100) {
            buffer.append('0');
            if (year < 10) {
                buffer.append('0');
            }
        }
    }
    buffer.append(Integer.toString(year));
    buffer.append('-');

    if (month < 10) {
        buffer.append('0');
    }
    buffer.append(Integer.toString(month));
    buffer.append('-');

    if (day < 10) {
        buffer.append('0');
    }
    buffer.append(Integer.toString(day));
    buffer.append('_');

    if (hour < 10) {
        buffer.append('0');
    }
    buffer.append(Integer.toString(hour));

    if (minutes < 10) {
        buffer.append('0');
    }
    buffer.append(Integer.toString(minutes));

    if (seconds < 10) {
        buffer.append('0');
    }
    buffer.append(Integer.toString(seconds));

    return buffer.toString();
}

protected void nextCalendar(Calendar calendar) {
    int i = calendar.get(Calendar.YEAR);
    int j = calendar.get(Calendar.MONTH);

    if (hourly) { 
        int k = calendar.get(Calendar.DAY_OF_MONTH);
        int l = calendar.get(Calendar.HOUR_OF_DAY) + 1;
        calendar.clear();
        calendar.set(i, j, k, l, 0);
    } else {
        int k = calendar.get(Calendar.DAY_OF_MONTH) + 1;
        calendar.clear();
        calendar.set(i, j, k);
    }
}

public String getDirectory() {
    return directory;
}

public void setDirectory(String directory) {
    if (directory == null || directory.length() == 0) {
        this.directory = "."; // Set to here
    } else {
        this.directory = directory;
    }
}

public String getPrefix() {
    return prefix;
}

public void setPrefix(String prefix) {
    if (prefix == null) {
        this.prefix = DEFAULT_PREFIX; // Set to default
    } else {
        this.prefix = prefix;
    }
}

public String getSuffix() {
    return suffix;
}

public void setSuffix(String suffix) {
    if (suffix == null) {
        this.suffix = ""; // Set to empty, not default
    } else {
        this.suffix = suffix;
    }
}

public void setHourly(boolean hourly) {
    this.hourly = hourly;
}

public boolean isHourly() {
    return this.hourly;
}
}

Here is my appender XML snippet:

<appender name="PRIMARY_APPENDER" class="com.stackoverflow.log4j.DistinctDailyFileAppender">
  <param name="Threshold" value="DEBUG"/>
  <param name="Directory" value="X:\\apps\\logs\\cheese\\"/>
  <param name="Append" value="true"/>
  <param name="Hourly" value="true"/>
  <param name="Prefix" value="appname_log."/>
  <param name="Suffix" value=".txt"/>

  <layout class="org.apache.log4j.PatternLayout">
    <param name="ConversionPattern" value="%d{HH:mm:ss,SSS} %-5p [%.3t] %-14.14c{1} %m%n"/>
  </layout>
</appender>