Source Code for Apache Log4j Core Implementation

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 and source package like You can download them at Apache Log4j Website.

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



 * 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the license for the specific language governing permissions and
 * limitations under the license.
package org.apache.logging.log4j.core.appender;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginBuilderAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
import org.apache.logging.log4j.core.util.Booleans;
import org.apache.logging.log4j.core.util.Integers;

 * Memory Mapped File Appender.
 * @since 2.1
@Plugin(name = "MemoryMappedFile", category = Core.CATEGORY_NAME, elementType = Appender.ELEMENT_TYPE, printObject = true)
public final class MemoryMappedFileAppender extends AbstractOutputStreamAppender<MemoryMappedFileManager> {

     * Builds RandomAccessFileAppender instances.
     * @param <B>
     *            The type to build
    public static class Builder<B extends Builder<B>> extends AbstractOutputStreamAppender.Builder<B>
            implements org.apache.logging.log4j.core.util.Builder<MemoryMappedFileAppender> {

        private String fileName;

        private boolean append = true;

        private int regionLength = MemoryMappedFileManager.DEFAULT_REGION_LENGTH;

        private boolean advertise;

        private String advertiseURI;

        public MemoryMappedFileAppender build() {
            final String name = getName();
            final int actualRegionLength = determineValidRegionLength(name, regionLength);

            if (name == null) {
                LOGGER.error("No name provided for MemoryMappedFileAppender");
                return null;

            if (fileName == null) {
                LOGGER.error("No filename provided for MemoryMappedFileAppender with name " + name);
                return null;
            final Layout<? extends Serializable> layout = getOrCreateLayout();
            final MemoryMappedFileManager manager = MemoryMappedFileManager.getFileManager(fileName, append, isImmediateFlush(),
                    actualRegionLength, advertiseURI, layout);
            if (manager == null) {
                return null;

            return new MemoryMappedFileAppender(name, layout, getFilter(), manager, fileName, isIgnoreExceptions(), false,
                    advertise ? getConfiguration().getAdvertiser() : null, getPropertyArray());

        public B setFileName(final String fileName) {
            this.fileName = fileName;
            return asBuilder();

        public B setAppend(final boolean append) {
            this.append = append;
            return asBuilder();

        public B setRegionLength(final int regionLength) {
            this.regionLength = regionLength;
            return asBuilder();

        public B setAdvertise(final boolean advertise) {
            this.advertise = advertise;
            return asBuilder();

        public B setAdvertiseURI(final String advertiseURI) {
            this.advertiseURI = advertiseURI;
            return asBuilder();


    private static final int BIT_POSITION_1GB = 30; // 2^30 ~= 1GB
    private static final int MAX_REGION_LENGTH = 1 << BIT_POSITION_1GB;
    private static final int MIN_REGION_LENGTH = 256;

    private final String fileName;
    private Object advertisement;
    private final Advertiser advertiser;

    private MemoryMappedFileAppender(final String name, final Layout<? extends Serializable> layout,
            final Filter filter, final MemoryMappedFileManager manager, final String filename,
            final boolean ignoreExceptions, final boolean immediateFlush, final Advertiser advertiser,
            final Property[] properties) {
        super(name, layout, filter, ignoreExceptions, immediateFlush, properties, manager);
        if (advertiser != null) {
            final Map<String, String> configuration = new HashMap<>(layout.getContentFormat());
            configuration.put("contentType", layout.getContentType());
            configuration.put("name", name);
            advertisement = advertiser.advertise(configuration);
        this.fileName = filename;
        this.advertiser = advertiser;

    public boolean stop(final long timeout, final TimeUnit timeUnit) {
        super.stop(timeout, timeUnit, false);
        if (advertiser != null) {
        return true;

     * Write the log entry rolling over the file when required.
     * @param event The LogEvent.
    public void append(final LogEvent event) {

        // Leverage the nice batching behaviour of async Loggers/Appenders:
        // we can signal the file manager that it needs to flush the buffer
        // to disk at the end of a batch.
        // From a user's point of view, this means that all log events are
        // _always_ available in the log file, without incurring the overhead
        // of immediateFlush=true.
        getManager().setEndOfBatch(event.isEndOfBatch()); // FIXME manager's EndOfBatch threadlocal can be deleted
        super.append(event); // TODO should only call force() if immediateFlush && endOfBatch?

     * Returns the file name this appender is associated with.
     * @return The File name.
    public String getFileName() {
        return this.fileName;

     * Returns the length of the memory mapped region.
     * @return the length of the memory mapped region
    public int getRegionLength() {
        return getManager().getRegionLength();

     * Create a Memory Mapped File Appender.
     * @param fileName The name and path of the file.
     * @param append "True" if the file should be appended to, "false" if it should be overwritten. The default is
     *            "true".
     * @param name The name of the Appender.
     * @param immediateFlush "true" if the contents should be flushed on every write, "false" otherwise. The default is
     *            "false".
     * @param regionLengthStr The buffer size, defaults to {@value MemoryMappedFileManager#DEFAULT_REGION_LENGTH}.
     * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise they
     *            are propagated to the caller.
     * @param layout The layout to use to format the event. If no layout is provided the default PatternLayout will be
     *            used.
     * @param filter The filter, if any, to use.
     * @param advertise "true" if the appender configuration should be advertised, "false" otherwise.
     * @param advertiseURI The advertised URI which can be used to retrieve the file contents.
     * @param config The Configuration.
     * @return The FileAppender.
     * @deprecated Use {@link #newBuilder()}.
    public static <B extends Builder<B>> MemoryMappedFileAppender createAppender(
            // @formatter:off
            final String fileName, //
            final String append, //
            final String name, //
            final String immediateFlush, //
            final String regionLengthStr, //
            final String ignore, //
            final Layout<? extends Serializable> layout, //
            final Filter filter, //
            final String advertise, //
            final String advertiseURI, //
            final Configuration config) {
            // @formatter:on

        final boolean isAppend = Booleans.parseBoolean(append, true);
        final boolean isImmediateFlush = Booleans.parseBoolean(immediateFlush, false);
        final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
        final boolean isAdvertise = Boolean.parseBoolean(advertise);
        final int regionLength = Integers.parseInt(regionLengthStr, MemoryMappedFileManager.DEFAULT_REGION_LENGTH);

        // @formatter:off
        return MemoryMappedFileAppender.<B>newBuilder()
        // @formatter:on

    public static <B extends Builder<B>> B newBuilder() {
        return new Builder<B>().asBuilder();

     * Converts the specified region length to a valid value.
    private static int determineValidRegionLength(final String name, final int regionLength) {
        if (regionLength > MAX_REGION_LENGTH) {
  "MemoryMappedAppender[{}] Reduced region length from {} to max length: {}", name, regionLength,
            return MAX_REGION_LENGTH;
        if (regionLength < MIN_REGION_LENGTH) {
  "MemoryMappedAppender[{}] Expanded region length from {} to min length: {}", name, regionLength,
            return MIN_REGION_LENGTH;
        final int result = Integers.ceilingNextPowerOfTwo(regionLength);
        if (regionLength != result) {
  "MemoryMappedAppender[{}] Rounded up region length from {} to next power of two: {}", name,
                    regionLength, result);
        return result;



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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