Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.rolling;

import static ch.qos.logback.core.CoreConstants.CODES_URL;

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

import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.rolling.helper.*;

When rolling over, FixedWindowRollingPolicy renames files
according to a fixed window algorithm.
For more information about this policy, please refer to the online manual at
http://logback.qos.ch/manual/appenders.html#FixedWindowRollingPolicy
Author:
Ceki Gülcü/**
 * When rolling over, <code>FixedWindowRollingPolicy</code> renames files
 * according to a fixed window algorithm.
 * 
 * For more information about this policy, please refer to the online manual at
 * http://logback.qos.ch/manual/appenders.html#FixedWindowRollingPolicy
 * 
 * @author Ceki G&uuml;lc&uuml;
 */
public class FixedWindowRollingPolicy extends RollingPolicyBase {
    static final String FNP_NOT_SET = "The \"FileNamePattern\" property must be set before using FixedWindowRollingPolicy. ";
    static final String PRUDENT_MODE_UNSUPPORTED = "See also "+CODES_URL+"#tbr_fnp_prudent_unsupported";
    static final String SEE_PARENT_FN_NOT_SET = "Please refer to "+CODES_URL+"#fwrp_parentFileName_not_set";
    int maxIndex;
    int minIndex;
    RenameUtil util = new RenameUtil();
    Compressor compressor;

    public static final String ZIP_ENTRY_DATE_PATTERN = "yyyy-MM-dd_HHmm";

    
It's almost always a bad idea to have a large window size, say over 20.
/**
     * It's almost always a bad idea to have a large window size, say over 20.
     */
    private static int MAX_WINDOW_SIZE = 20;

    public FixedWindowRollingPolicy() {
        minIndex = 1;
        maxIndex = 7;
    }

    public void start() {
        util.setContext(this.context);

        if (fileNamePatternStr != null) {
            fileNamePattern = new FileNamePattern(fileNamePatternStr, this.context);
            determineCompressionMode();
        } else {
            addError(FNP_NOT_SET);
            addError(CoreConstants.SEE_FNP_NOT_SET);
            throw new IllegalStateException(FNP_NOT_SET + CoreConstants.SEE_FNP_NOT_SET);
        }

        if (isParentPrudent()) {
            addError("Prudent mode is not supported with FixedWindowRollingPolicy.");
            addError(PRUDENT_MODE_UNSUPPORTED);
            throw new IllegalStateException("Prudent mode is not supported.");
        }

        if (getParentsRawFileProperty() == null) {
            addError("The File name property must be set before using this rolling policy.");
            addError(SEE_PARENT_FN_NOT_SET);
            throw new IllegalStateException("The \"File\" option must be set.");
        }

        if (maxIndex < minIndex) {
            addWarn("MaxIndex (" + maxIndex + ") cannot be smaller than MinIndex (" + minIndex + ").");
            addWarn("Setting maxIndex to equal minIndex.");
            maxIndex = minIndex;
        }

        final int maxWindowSize = getMaxWindowSize();
        if ((maxIndex - minIndex) > maxWindowSize) {
            addWarn("Large window sizes are not allowed.");
            maxIndex = minIndex + maxWindowSize;
            addWarn("MaxIndex reduced to " + maxIndex);
        }

        IntegerTokenConverter itc = fileNamePattern.getIntegerTokenConverter();

        if (itc == null) {
            throw new IllegalStateException("FileNamePattern [" + fileNamePattern.getPattern() + "] does not contain a valid IntegerToken");
        }

        if (compressionMode == CompressionMode.ZIP) {
            String zipEntryFileNamePatternStr = transformFileNamePatternFromInt2Date(fileNamePatternStr);
            zipEntryFileNamePattern = new FileNamePattern(zipEntryFileNamePatternStr, context);
        }
        compressor = new Compressor(compressionMode);
        compressor.setContext(this.context);
        super.start();
    }

    
Subclasses can override this method to increase the max window size, if required.  This is to
address LOGBACK-266.
Returns:
/**
     * Subclasses can override this method to increase the max window size, if required.  This is to
     * address LOGBACK-266.
     * @return

     */
    protected int getMaxWindowSize() {
        return MAX_WINDOW_SIZE;
    }

    private String transformFileNamePatternFromInt2Date(String fileNamePatternStr) {
        String slashified = FileFilterUtil.slashify(fileNamePatternStr);
        String stemOfFileNamePattern = FileFilterUtil.afterLastSlash(slashified);
        return stemOfFileNamePattern.replace("%i", "%d{" + ZIP_ENTRY_DATE_PATTERN + "}");
    }

    public void rollover() throws RolloverFailure {

        // Inside this method it is guaranteed that the hereto active log file is
        // closed.
        // If maxIndex <= 0, then there is no file renaming to be done.
        if (maxIndex >= 0) {
            // Delete the oldest file, to keep Windows happy.
            File file = new File(fileNamePattern.convertInt(maxIndex));

            if (file.exists()) {
                file.delete();
            }

            // Map {(maxIndex - 1), ..., minIndex} to {maxIndex, ..., minIndex+1}
            for (int i = maxIndex - 1; i >= minIndex; i--) {
                String toRenameStr = fileNamePattern.convertInt(i);
                File toRename = new File(toRenameStr);
                // no point in trying to rename an inexistent file
                if (toRename.exists()) {
                    util.rename(toRenameStr, fileNamePattern.convertInt(i + 1));
                } else {
                    addInfo("Skipping roll-over for inexistent file " + toRenameStr);
                }
            }

            // move active file name to min
            switch (compressionMode) {
            case NONE:
                util.rename(getActiveFileName(), fileNamePattern.convertInt(minIndex));
                break;
            case GZ:
                compressor.compress(getActiveFileName(), fileNamePattern.convertInt(minIndex), null);
                break;
            case ZIP:
                compressor.compress(getActiveFileName(), fileNamePattern.convertInt(minIndex), zipEntryFileNamePattern.convert(new Date()));
                break;
            }
        }
    }

    
Return the value of the parent's RawFile property.
/**
     * Return the value of the parent's RawFile property.
     */
    public String getActiveFileName() {
        return getParentsRawFileProperty();
    }

    public int getMaxIndex() {
        return maxIndex;
    }

    public int getMinIndex() {
        return minIndex;
    }

    public void setMaxIndex(int maxIndex) {
        this.maxIndex = maxIndex;
    }

    public void setMinIndex(int minIndex) {
        this.minIndex = minIndex;
    }
}