log4j-core/src/main/java/org/apache/logging/log4j/core/appender/rolling/action/PathSortByModificationTime.java

/*
 * 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.
 */

package org.apache.logging.log4j.core.appender.rolling.action;

import java.io.Serializable;

import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.plugins.Plugin;
import org.apache.logging.log4j.plugins.PluginAttribute;
import org.apache.logging.log4j.plugins.PluginFactory;

/**
 * {@link PathSorter} that sorts path by their LastModified attribute.
 */
@Plugin(name = "SortByModificationTime", category = Core.CATEGORY_NAME, printObject = true)
public class PathSortByModificationTime implements PathSorter, Serializable {

    private static final long serialVersionUID = 1L;

    private final boolean recentFirst;
    private final int multiplier;

    /**
     * Constructs a new SortByModificationTime sorter.
     *
     * @param recentFirst if true, most recently modified paths should come first
     */
    public PathSortByModificationTime(final boolean recentFirst) {
        this.recentFirst = recentFirst;
        this.multiplier = recentFirst ? 1 : -1;
    }

    /**
     * Create a PathSorter that sorts by lastModified time.
     *
     * @param recentFirst if true, most recently modified paths should come first.
     * @return A PathSorter.
     */
    @PluginFactory
    public static PathSorter createSorter(
            @PluginAttribute(defaultBoolean = true) final boolean recentFirst) {
        return new PathSortByModificationTime(recentFirst);
    }

    /**
     * Returns whether this sorter sorts recent files first.
     *
     * @return whether this sorter sorts recent files first
     */
    public boolean isRecentFirst() {
        return recentFirst;
    }

    /*
     * (non-Javadoc)
     *
     * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
     */
    @Override
    public int compare(final PathWithAttributes path1, final PathWithAttributes path2) {
        final long lastModified1 = path1.getAttributes().lastModifiedTime().toMillis();
        final long lastModified2 = path2.getAttributes().lastModifiedTime().toMillis();
        int result = Long.signum(lastModified2 - lastModified1);
        if (result == 0) { // if same time compare paths lexicographically
            try {
                // assuming paths contain counters and dates, use reverse lexicographical order:
                // 20151129 before 20151128, path-2.log before path-1.log
                result = path2.getPath().compareTo(path1.getPath());
            } catch (final ClassCastException ex) {
                result = path2.getPath().toString().compareTo(path1.getPath().toString());
            }
        }
        return multiplier * result;
    }
}