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/config/LockingReliabilityStrategy.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.config;

import java.util.Objects;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.message.Message;
import org.apache.logging.log4j.util.Supplier;

/**
 * ReliabilityStrategy that uses read/write locks to prevent the LoggerConfig from stopping while it is in use.
 */
public class LockingReliabilityStrategy implements ReliabilityStrategy, LocationAwareReliabilityStrategy {
    private final LoggerConfig loggerConfig;
    private final ReadWriteLock reconfigureLock = new ReentrantReadWriteLock();
    private volatile boolean isStopping;

    public LockingReliabilityStrategy(final LoggerConfig loggerConfig) {
        this.loggerConfig = Objects.requireNonNull(loggerConfig, "loggerConfig was null");
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.logging.log4j.core.config.ReliabilityStrategy#log(org.apache.logging.log4j.util.Supplier,
     * java.lang.String, java.lang.String, org.apache.logging.log4j.Marker, org.apache.logging.log4j.Level,
     * org.apache.logging.log4j.message.Message, java.lang.Throwable)
     */
    @Override
    public void log(final Supplier<LoggerConfig> reconfigured, final String loggerName, final String fqcn,
            final Marker marker, final Level level, final Message data, final Throwable t) {

        final LoggerConfig config = getActiveLoggerConfig(reconfigured);
        try {
            config.log(loggerName, fqcn, marker, level, data, t);
        } finally {
            config.getReliabilityStrategy().afterLogEvent();
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.logging.log4j.core.config.ReliabilityStrategy#log(org.apache.logging.log4j.util.Supplier,
     * java.lang.String, java.lang.String, java.lang.StackTraceElement, org.apache.logging.log4j.Marker,
     * org.apache.logging.log4j.Level, org.apache.logging.log4j.message.Message, java.lang.Throwable)
     */
    @Override
    public void log(final Supplier<LoggerConfig> reconfigured, final String loggerName, final String fqcn,
        final StackTraceElement location, final Marker marker, final Level level, final Message data,
        final Throwable t) {
        final LoggerConfig config = getActiveLoggerConfig(reconfigured);
        try {
            config.log(loggerName, fqcn, location, marker, level, data, t);
        } finally {
            config.getReliabilityStrategy().afterLogEvent();
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.logging.log4j.core.config.ReliabilityStrategy#log(org.apache.logging.log4j.util.Supplier,
     * org.apache.logging.log4j.core.LogEvent)
     */
    @Override
    public void log(final Supplier<LoggerConfig> reconfigured, final LogEvent event) {
        final LoggerConfig config = getActiveLoggerConfig(reconfigured);
        try {
            config.log(event);
        } finally {
            config.getReliabilityStrategy().afterLogEvent();
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.apache.logging.log4j.core.config.ReliabilityStrategy#beforeLogEvent(org.apache.logging.log4j.core.config.
     * LoggerConfig, org.apache.logging.log4j.util.Supplier)
     */
    @Override
    public LoggerConfig getActiveLoggerConfig(final Supplier<LoggerConfig> next) {
        LoggerConfig result = this.loggerConfig;
        if (!beforeLogEvent()) {
            result = next.get();
            return result == this.loggerConfig ? result : result.getReliabilityStrategy().getActiveLoggerConfig(next);
        }
        return result;
    }

    private boolean beforeLogEvent() {
        reconfigureLock.readLock().lock();
        if (isStopping) {
            reconfigureLock.readLock().unlock();
            return false;
        }
        return true;
    }

    @Override
    public void afterLogEvent() {
        reconfigureLock.readLock().unlock();
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.logging.log4j.core.config.ReliabilityStrategy#beforeStopAppenders()
     */
    @Override
    public void beforeStopAppenders() {
        reconfigureLock.writeLock().lock();
        try {
            isStopping = true;
        } finally {
            reconfigureLock.writeLock().unlock();
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.apache.logging.log4j.core.config.ReliabilityStrategy#beforeStopConfiguration(org.apache.logging.log4j.core
     * .config.Configuration)
     */
    @Override
    public void beforeStopConfiguration(final Configuration configuration) {
        // no action
    }

}

⏎ org/apache/logging/log4j/core/config/LockingReliabilityStrategy.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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