001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.async;
018
019import org.apache.logging.log4j.Level;
020import org.apache.logging.log4j.core.util.Log4jThread;
021
022/**
023 * Default router: enqueue the event for asynchronous logging in the background thread, unless the current thread is the
024 * background thread and the queue is full (enqueueing would cause a deadlock). In that case send the event directly to
025 * the appender (in the current thread).
026 */
027public class DefaultAsyncQueueFullPolicy implements AsyncQueueFullPolicy {
028    @Override
029    public EventRoute getRoute(final long backgroundThreadId, final Level level) {
030
031        // LOG4J2-471: prevent deadlock when RingBuffer is full and object
032        // being logged calls Logger.log() from its toString() method
033        Thread currentThread = Thread.currentThread();
034        if (currentThread.getId() == backgroundThreadId
035                // Threads owned by log4j are most likely to result in
036                // deadlocks because they generally consume events.
037                // This prevents deadlocks between AsyncLoggerContext
038                // disruptors.
039                || currentThread instanceof Log4jThread) {
040            return EventRoute.SYNCHRONOUS;
041        }
042        return EventRoute.ENQUEUE;
043    }
044}