Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-2.14.1.jar.

Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/appender/routing/IdlePurgePolicy.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.routing;

import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.core.AbstractLifeCycle;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.ConfigurationScheduler;
import org.apache.logging.log4j.core.config.Scheduled;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;

/**
 * Policy is purging appenders that were not in use specified time in minutes
 */
@Plugin(name = "IdlePurgePolicy", category = Core.CATEGORY_NAME, printObject = true)
@Scheduled
public class IdlePurgePolicy extends AbstractLifeCycle implements PurgePolicy, Runnable {

    private final long timeToLive;
    private final long checkInterval;
    private final ConcurrentMap<String, Long> appendersUsage = new ConcurrentHashMap<>();
    private RoutingAppender routingAppender;
    private final ConfigurationScheduler scheduler;
    private volatile ScheduledFuture<?> future;

    public IdlePurgePolicy(final long timeToLive, final long checkInterval, final ConfigurationScheduler scheduler) {
        this.timeToLive = timeToLive;
        this.checkInterval = checkInterval;
        this.scheduler = scheduler;
    }

    @Override
    public void initialize(@SuppressWarnings("hiding") final RoutingAppender routingAppender) {
        this.routingAppender = routingAppender;
    }

    @Override
    public boolean stop(final long timeout, final TimeUnit timeUnit) {
        setStopping();
        final boolean stopped = stop(future);
        setStopped();
        return stopped;
    }

    /**
     * Purging appenders that were not in use specified time
     */
    @Override
    public void purge() {
        final long createTime = System.currentTimeMillis() - timeToLive;
        for (final Entry<String, Long> entry : appendersUsage.entrySet()) {
            long entryValue = entry.getValue();
            if (entryValue < createTime) {
                if (appendersUsage.remove(entry.getKey(), entryValue)) {
                    LOGGER.debug("Removing appender {}", entry.getKey());
                    routingAppender.deleteAppender(entry.getKey());
                }
            }
        }
    }

    @Override
    public void update(final String key, final LogEvent event) {
        final long now = System.currentTimeMillis();
        appendersUsage.put(key, now);
        if (future == null) {
            synchronized (this) {
                if (future == null) {
                    scheduleNext();
                }
            }
        }

    }

    @Override
    public void run() {
        purge();
        scheduleNext();
    }

    private void scheduleNext() {
        long updateTime = Long.MAX_VALUE;
        for (final Entry<String, Long> entry : appendersUsage.entrySet()) {
            if (entry.getValue() < updateTime) {
                updateTime = entry.getValue();
            }
        }

        if (updateTime < Long.MAX_VALUE) {
            final long interval = timeToLive - (System.currentTimeMillis() - updateTime);
            future = scheduler.schedule(this, interval, TimeUnit.MILLISECONDS);
        } else {
            // reset to initial state - in case of all appenders already purged
            future = scheduler.schedule(this, checkInterval, TimeUnit.MILLISECONDS);
        }
    }

    /**
     * Create the PurgePolicy
     *
     * @param timeToLive    the number of increments of timeUnit before the Appender should be purged.
     * @param checkInterval when all appenders purged, the number of increments of timeUnit to check if any appenders appeared
     * @param timeUnit      the unit of time the timeToLive and the checkInterval is expressed in.
     * @return The Routes container.
     */
    @PluginFactory
    public static PurgePolicy createPurgePolicy(
        @PluginAttribute("timeToLive") final String timeToLive,
        @PluginAttribute("checkInterval") final String checkInterval,
        @PluginAttribute("timeUnit") final String timeUnit,
        @PluginConfiguration final Configuration configuration) {

        if (timeToLive == null) {
            LOGGER.error("A timeToLive value is required");
            return null;
        }
        TimeUnit units;
        if (timeUnit == null) {
            units = TimeUnit.MINUTES;
        } else {
            try {
                units = TimeUnit.valueOf(timeUnit.toUpperCase());
            } catch (final Exception ex) {
                LOGGER.error("Invalid timeUnit value {}. timeUnit set to MINUTES", timeUnit, ex);
                units = TimeUnit.MINUTES;
            }
        }

        long ttl = units.toMillis(Long.parseLong(timeToLive));
        if (ttl < 0) {
            LOGGER.error("timeToLive must be positive. timeToLive set to 0");
            ttl = 0;
        }

        long ci;
        if (checkInterval == null) {
            ci = ttl;
        } else {
            ci = units.toMillis(Long.parseLong(checkInterval));
            if (ci < 0) {
                LOGGER.error("checkInterval must be positive. checkInterval set equal to timeToLive = {}", ttl);
                ci = ttl;
            }
        }

        return new IdlePurgePolicy(ttl, ci, configuration.getScheduler());
    }

    @Override
    public String toString() {
        return "timeToLive=" + timeToLive;
    }

}

⏎ org/apache/logging/log4j/core/appender/routing/IdlePurgePolicy.java

Or download all of them as a single archive file:

File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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