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Reload4j revives EOLed log4j 1.x
There is a newer version: 1.2.25
/*
 * 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.log4j;

import org.apache.log4j.helpers.AppenderAttachableImpl;
import org.apache.log4j.spi.LoggingEvent;

/**
 * Obsolete AsyncAppender dispatcher provided for compatibility only.
 *
 * @deprecated Since 1.3.
 */
class Dispatcher extends Thread {
    /**
     * @deprecated
     */
    private org.apache.log4j.helpers.BoundedFIFO bf;
    private AppenderAttachableImpl aai;
    private boolean interrupted = false;
    AsyncAppender container;

    /**
     *
     * @param bf
     * @param container
     * @deprecated
     */
    Dispatcher(org.apache.log4j.helpers.BoundedFIFO bf, AsyncAppender container) {
	this.bf = bf;
	this.container = container;
	this.aai = container.aai;

	// It is the user's responsibility to close appenders before
	// exiting.
	this.setDaemon(true);

	// set the dispatcher priority to lowest possible value
	this.setPriority(Thread.MIN_PRIORITY);
	this.setName("Dispatcher-" + getName());

	// set the dispatcher priority to MIN_PRIORITY plus or minus 2
	// depending on the direction of MIN to MAX_PRIORITY.
	// + (Thread.MAX_PRIORITY > Thread.MIN_PRIORITY ? 1 : -1)*2);
    }

    void close() {
	synchronized (bf) {
	    interrupted = true;

	    // We have a waiting dispacther if and only if bf.length is
	    // zero. In that case, we need to give it a death kiss.
	    if (bf.length() == 0) {
		bf.notify();
	    }
	}
    }

    /**
     * The dispatching strategy is to wait until there are events in the buffer to
     * process. After having processed an event, we release the monitor (variable
     * bf) so that new events can be placed in the buffer, instead of keeping the
     * monitor and processing the remaining events in the buffer.
     *
     * 
     * Other approaches might yield better results.
     * 
     */
    public void run() {
	// Category cat = Category.getInstance(Dispatcher.class.getName());
	LoggingEvent event;

	while (true) {
	    synchronized (bf) {
		if (bf.length() == 0) {
		    // Exit loop if interrupted but only if the the buffer is empty.
		    if (interrupted) {
			// cat.info("Exiting.");
			break;
		    }

		    try {
			// LogLog.debug("Waiting for new event to dispatch.");
			bf.wait();
		    } catch (InterruptedException e) {
			break;
		    }
		}

		event = bf.get();

		if (bf.wasFull()) {
		    // LogLog.debug("Notifying AsyncAppender about freed space.");
		    bf.notify();
		}
	    }

	    // synchronized
	    synchronized (container.aai) {
		if ((aai != null) && (event != null)) {
		    aai.appendLoopOnAppenders(event);
		}
	    }
	}

	// while
	// close and remove all appenders
	aai.removeAllAppenders();
    }
}