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/db/AbstractDatabaseAppender.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.db;

import java.io.Serializable;
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.LoggingException;
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.appender.AbstractAppender;
import org.apache.logging.log4j.core.appender.AppenderLoggingException;
import org.apache.logging.log4j.core.config.Property;

/**
 * An abstract Appender for writing events to a database of some type, be it relational or NoSQL. All database appenders
 * should inherit from this base appender. Three implementations are currently provided:
 * {@link org.apache.logging.log4j.core.appender.db.jdbc JDBC}, {@link org.apache.logging.log4j.core.appender.db.jpa
 * JPA}, and {@link org.apache.logging.log4j.core.appender.nosql NoSQL}.
 *
 * @param <T> Specifies which type of {@link AbstractDatabaseManager} this Appender requires.
 */
public abstract class AbstractDatabaseAppender<T extends AbstractDatabaseManager> extends AbstractAppender {

    public static class Builder<B extends Builder<B>> extends AbstractAppender.Builder<B> {
        // empty for now.
    }
    
    public static final int DEFAULT_RECONNECT_INTERVAL_MILLIS = 5000;
    
    private final ReadWriteLock lock = new ReentrantReadWriteLock();
    private final Lock readLock = lock.readLock();
    private final Lock writeLock = lock.writeLock();
    private T manager;

    /**
     * Instantiates the base appender.
     *
     * @param name The appender name.
     * @param filter The filter, if any, to use.
     * @param ignoreExceptions If {@code true} exceptions encountered when appending events are logged; otherwise
     *                         they are propagated to the caller.
     * @param manager The matching {@link AbstractDatabaseManager} implementation.
     * @deprecated Use {@link #AbstractDatabaseAppender(String, Filter, Layout, boolean, Property[], AbstractDatabaseManager)}.
     */
    @Deprecated
    protected AbstractDatabaseAppender(final String name, final Filter filter, final boolean ignoreExceptions,
                                       final T manager) {
        super(name, filter, null, ignoreExceptions, Property.EMPTY_ARRAY);
        this.manager = manager;
    }

    /**
     * Instantiates the base appender.
     *
     * @param name The appender name.
     * @param filter The filter, if any, to use.
     * @param layout The layout to use to format the event.
     * @param ignoreExceptions If {@code true} exceptions encountered when appending events are logged; otherwise
     *                         they are propagated to the caller.
     * @param manager The matching {@link AbstractDatabaseManager} implementation.
     */
    protected AbstractDatabaseAppender(final String name, final Filter filter,
            final Layout<? extends Serializable> layout, final boolean ignoreExceptions,
            final Property[] properties, final T manager) {
        super(name, filter, layout, ignoreExceptions, properties);
        this.manager = manager;
    }

    /**
     * Instantiates the base appender.
     *
     * @param name The appender name.
     * @param filter The filter, if any, to use.
     * @param layout The layout to use to format the event.
     * @param ignoreExceptions If {@code true} exceptions encountered when appending events are logged; otherwise
     *                         they are propagated to the caller.
     * @param manager The matching {@link AbstractDatabaseManager} implementation.
     * @deprecated Use {@link #AbstractDatabaseAppender(String, Filter, Layout, boolean, Property[], AbstractDatabaseManager)}
     */
    @Deprecated
    protected AbstractDatabaseAppender(final String name, final Filter filter,
            final Layout<? extends Serializable> layout, final boolean ignoreExceptions, final T manager) {
        super(name, filter, layout, ignoreExceptions, Property.EMPTY_ARRAY);
        this.manager = manager;
    }

    @Override
    public final void append(final LogEvent event) {
        this.readLock.lock();
        try {
            this.getManager().write(event, toSerializable(event));
        } catch (final LoggingException e) {
            LOGGER.error("Unable to write to database [{}] for appender [{}].", this.getManager().getName(),
                    this.getName(), e);
            throw e;
        } catch (final Exception e) {
            LOGGER.error("Unable to write to database [{}] for appender [{}].", this.getManager().getName(),
                    this.getName(), e);
            throw new AppenderLoggingException("Unable to write to database in appender: " + e.getMessage(), e);
        } finally {
            this.readLock.unlock();
        }
    }

    /**
     * This always returns {@code null}, as database appenders do not use a single layout. The JPA and NoSQL appenders
     * do not use a layout at all. The JDBC appender has a layout-per-column pattern.
     *
     * @return {@code null}.
     */
    @Override
    public final Layout<LogEvent> getLayout() {
        return null;
    }

    /**
     * Returns the underlying manager in use within this appender.
     *
     * @return the manager.
     */
    public final T getManager() {
        return this.manager;
    }

    /**
     * Replaces the underlying manager in use within this appender. This can be useful for manually changing the way log
     * events are written to the database without losing buffered or in-progress events. The existing manager is
     * released only after the new manager has been installed. This method is thread-safe.
     *
     * @param manager The new manager to install.
     */
    protected final void replaceManager(final T manager) {
        this.writeLock.lock();
        try {
            final T old = this.getManager();
            if (!manager.isRunning()) {
                manager.startup();
            }
            this.manager = manager;
            old.close();
        } finally {
            this.writeLock.unlock();
        }
    }

    @Override
    public final void start() {
        if (this.getManager() == null) {
            LOGGER.error("No AbstractDatabaseManager set for the appender named [{}].", this.getName());
        }
        super.start();
        if (this.getManager() != null) {
            this.getManager().startup();
        }
    }

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

⏎ org/apache/logging/log4j/core/appender/db/AbstractDatabaseAppender.java

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