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/async/DiscardingAsyncQueueFullPolicy.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.async;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;

import java.util.Objects;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Discarding router extends the DefaultAsyncQueueFullPolicy by first verifying if the queue is fuller than the specified
 * threshold ratio; if this is the case, log events {@linkplain Level#isMoreSpecificThan(Level) more specific} than
 * the specified threshold level are dropped. If this is not the case, the {@linkplain DefaultAsyncQueueFullPolicy
 * default routing rules hold.
 */
public class DiscardingAsyncQueueFullPolicy extends DefaultAsyncQueueFullPolicy {
    private static final Logger LOGGER = StatusLogger.getLogger();

    private final Level thresholdLevel;
    private final AtomicLong discardCount = new AtomicLong();

    /**
     * Constructs a router that will discard events {@linkplain Level#isLessSpecificThan(Level) equal or less specific}
     * than the specified threshold level when the queue is full.
     *
     * @param thresholdLevel level of events to discard
     */
    public DiscardingAsyncQueueFullPolicy(final Level thresholdLevel) {
        this.thresholdLevel = Objects.requireNonNull(thresholdLevel, "thresholdLevel");
    }

    @Override
    public EventRoute getRoute(final long backgroundThreadId, final Level level) {
        if (level.isLessSpecificThan(thresholdLevel)) {
            if (discardCount.getAndIncrement() == 0) {
                LOGGER.warn("Async queue is full, discarding event with level {}. " +
                        "This message will only appear once; future events from {} " +
                        "are silently discarded until queue capacity becomes available.",
                        level, thresholdLevel);
            }
            return EventRoute.DISCARD;
        }
        return super.getRoute(backgroundThreadId, level);
    }

    public static long getDiscardCount(final AsyncQueueFullPolicy router) {
        if (router instanceof DiscardingAsyncQueueFullPolicy) {
            return ((DiscardingAsyncQueueFullPolicy) router).discardCount.get();
        }
        return 0;
    }

    public Level getThresholdLevel() {
        return thresholdLevel;
    }
}

⏎ org/apache/logging/log4j/core/async/DiscardingAsyncQueueFullPolicy.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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