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.message;
018
019import org.apache.logging.log4j.status.StatusLogger;
020
021/**
022 * Creates {@link FormattedMessage} instances for {@link MessageFactory2} methods (and {@link MessageFactory} by
023 * extension.)
024 * <p>
025 * Creates {@link SimpleMessage} objects that do not retain a reference to the parameter object.
026 * </p>
027 * <p>
028 * Intended for use by the {@link StatusLogger}: this logger retains a queue of recently logged messages in memory,
029 * causing memory leaks in web applications. (LOG4J2-1176)
030 * </p>
031 * <p>
032 * This class is immutable.
033 * </p>
034 * <h4>Note to implementors</h4>
035 * <p>
036 * This class does <em>not</em> implement any {@link MessageFactory2} methods and lets the superclass funnel those calls
037 * through {@link #newMessage(String, Object...)}.
038 * </p>
039 */
040public final class ParameterizedNoReferenceMessageFactory extends AbstractMessageFactory {
041    private static final long serialVersionUID = 5027639245636870500L;
042
043    /**
044     * Message implementation that only keeps a reference to the error text and the error (if any), not to the
045     * message parameters, in order to avoid memory leaks. This addresses LOG4J2-1368.
046     * @since 2.6
047     */
048    static class StatusMessage implements Message {
049        private final String formattedMessage;
050        private final Throwable throwable;
051
052        public StatusMessage(final String formattedMessage, final Throwable throwable) {
053            this.formattedMessage = formattedMessage;
054            this.throwable = throwable;
055        }
056
057        @Override
058        public String getFormattedMessage() {
059            return formattedMessage;
060        }
061
062        @Override
063        public String getFormat() {
064            return formattedMessage;
065        }
066
067        @Override
068        public Object[] getParameters() {
069            return null;
070        }
071
072        @Override
073        public Throwable getThrowable() {
074            return throwable;
075        }
076    }
077
078    /**
079     * Constructs a message factory with default flow strings.
080     */
081    public ParameterizedNoReferenceMessageFactory() {
082        super();
083    }
084
085    /**
086     * Instance of ParameterizedStatusMessageFactory.
087     */
088    public static final ParameterizedNoReferenceMessageFactory INSTANCE = new ParameterizedNoReferenceMessageFactory();
089
090    /**
091     * Creates {@link SimpleMessage} instances containing the formatted parameterized message string.
092     *
093     * @param message The message pattern.
094     * @param params The message parameters.
095     * @return The Message.
096     *
097     * @see MessageFactory#newMessage(String, Object...)
098     */
099    @Override
100    public Message newMessage(final String message, final Object... params) {
101        if (params == null) {
102            return new SimpleMessage(message);
103        }
104        final ParameterizedMessage msg = new ParameterizedMessage(message, params);
105        return new StatusMessage(msg.getFormattedMessage(), msg.getThrowable());
106    }
107}