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/AbstractWriterAppender.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;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.StringLayout;
import org.apache.logging.log4j.core.config.Property;

/**
 * Appends log events as strings to a writer.
 *
 * @param <M>
 *            The kind of {@link WriterManager} under management
 */
public abstract class AbstractWriterAppender<M extends WriterManager> extends AbstractAppender {

    /**
     * Immediate flush means that the underlying writer will be flushed at the
     * end of each append operation. Immediate flush is slower but ensures that
     * each append request is actually written. If <code>immediateFlush</code>
     * is set to {@code false}, then there is a good chance that the last few
     * logs events are not actually written to persistent media if and when the
     * application crashes.
     */
    protected final boolean immediateFlush;
    private final M manager;
    private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
    private final Lock readLock = readWriteLock.readLock();

    /**
     * Instantiates.
     *
     * @param name
     *            The name of the Appender.
     * @param layout
     *            The layout to format the message.
     * @param properties
     *            Optional properties.
     * @param manager
     *            The OutputStreamManager.
     */
    protected AbstractWriterAppender(final String name, final StringLayout layout, final Filter filter,
            final boolean ignoreExceptions, final boolean immediateFlush, final Property[] properties, final M manager) {
        super(name, filter, layout, ignoreExceptions, properties);
        this.manager = manager;
        this.immediateFlush = immediateFlush;
    }

    /**
     * Instantiates.
     *
     * @param name
     *            The name of the Appender.
     * @param layout
     *            The layout to format the message.
     * @param manager
     *            The OutputStreamManager.
     * @deprecated Use {@link #AbstractWriterAppender(String, StringLayout, Filter, boolean, boolean, Property[], WriterManager)}.
     */
    @Deprecated
    protected AbstractWriterAppender(final String name, final StringLayout layout, final Filter filter,
            final boolean ignoreExceptions, final boolean immediateFlush, final M manager) {
        super(name, filter, layout, ignoreExceptions, Property.EMPTY_ARRAY);
        this.manager = manager;
        this.immediateFlush = immediateFlush;
    }

    /**
     * Actual writing occurs here.
     * <p>
     * Most subclasses will need to override this method.
     * </p>
     *
     * @param event
     *            The LogEvent.
     */
    @Override
    public void append(final LogEvent event) {
        readLock.lock();
        try {
            final String str = getStringLayout().toSerializable(event);
            if (str.length() > 0) {
                manager.write(str);
                if (this.immediateFlush || event.isEndOfBatch()) {
                    manager.flush();
                }
            }
        } catch (final AppenderLoggingException ex) {
            error("Unable to write " + manager.getName() + " for appender " + getName(), event, ex);
            throw ex;
        } finally {
            readLock.unlock();
        }
    }

    /**
     * Gets the manager.
     *
     * @return the manager.
     */
    public M getManager() {
        return manager;
    }

    public StringLayout getStringLayout() {
        return (StringLayout) getLayout();
    }

    @Override
    public void start() {
        if (getLayout() == null) {
            LOGGER.error("No layout set for the appender named [{}].", getName());
        }
        if (manager == null) {
            LOGGER.error("No OutputStreamManager set for the appender named [{}].", getName());
        }
        super.start();
    }

    @Override
    public boolean stop(final long timeout, final TimeUnit timeUnit) {
        setStopping();
        boolean stopped = super.stop(timeout, timeUnit, false);
        stopped &= manager.stop(timeout, timeUnit);
        setStopped();
        return stopped;
    }
}

⏎ org/apache/logging/log4j/core/appender/AbstractWriterAppender.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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