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/rolling/OnStartupTriggeringPolicy.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;

import java.lang.reflect.Method;

import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.LogEvent;
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.PluginFactory;
import org.apache.logging.log4j.core.util.Loader;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * Triggers a rollover on every restart, but only if the file size is greater than zero.
 */
@Plugin(name = "OnStartupTriggeringPolicy", category = Core.CATEGORY_NAME, printObject = true)
public class OnStartupTriggeringPolicy extends AbstractTriggeringPolicy {

    private static final long JVM_START_TIME = initStartTime();

    private final long minSize;

    private OnStartupTriggeringPolicy(final long minSize) {
        this.minSize = minSize;
    }

    /**
     * Returns the result of {@code ManagementFactory.getRuntimeMXBean().getStartTime()},
     * or the current system time if JMX is not available.
     */
    private static long initStartTime() {
        // LOG4J2-379:
        // We'd like to call ManagementFactory.getRuntimeMXBean().getStartTime(),
        // but Google App Engine throws a java.lang.NoClassDefFoundError
        // "java.lang.management.ManagementFactory is a restricted class".
        // The reflection is necessary because without it, Google App Engine
        // will refuse to initialize this class.
        try {
            final Class<?> factoryClass = Loader.loadSystemClass("java.lang.management.ManagementFactory");
            final Method getRuntimeMXBean = factoryClass.getMethod("getRuntimeMXBean");
            final Object runtimeMXBean = getRuntimeMXBean.invoke(null);

            final Class<?> runtimeMXBeanClass = Loader.loadSystemClass("java.lang.management.RuntimeMXBean");
            final Method getStartTime = runtimeMXBeanClass.getMethod("getStartTime");
            final Long result = (Long) getStartTime.invoke(runtimeMXBean);

            return result;
        } catch (final Throwable t) {
            StatusLogger.getLogger().error("Unable to call ManagementFactory.getRuntimeMXBean().getStartTime(), "
                    + "using system time for OnStartupTriggeringPolicy", t);
            // We have little option but to declare "now" as the beginning of time.
            return System.currentTimeMillis();
        }
    }

    /**
     * Provide the RollingFileManager to the policy.
     * @param manager The RollingFileManager.
     */
    @Override
    public void initialize(final RollingFileManager manager) {
        if (manager.getFileTime() < JVM_START_TIME && manager.getFileSize() >= minSize) {
            StatusLogger.getLogger().debug("Initiating rollover at startup");
            if (minSize == 0) {
                manager.setRenameEmptyFiles(true);
            }
            manager.skipFooter(true);
            manager.rollover();
            manager.skipFooter(false);
        }
    }

    /**
     * Determine if a rollover should be triggered.
     * @param event   A reference to the current event.
     * @return true if the target file's timestamp is older than the JVM start time.
     */
    @Override
    public boolean isTriggeringEvent(final LogEvent event) {
        return false;
    }

    @Override
    public String toString() {
        return "OnStartupTriggeringPolicy";
    }

    @PluginFactory
    public static OnStartupTriggeringPolicy createPolicy(
            @PluginAttribute(value = "minSize", defaultLong = 1) final long minSize) {
        return new OnStartupTriggeringPolicy(minSize);
    }
}

⏎ org/apache/logging/log4j/core/appender/rolling/OnStartupTriggeringPolicy.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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