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 */
017 package org.apache.logging.log4j.core.appender;
018
019 import java.io.Serializable;
020 import java.util.concurrent.locks.Lock;
021 import java.util.concurrent.locks.ReadWriteLock;
022 import java.util.concurrent.locks.ReentrantReadWriteLock;
023
024 import org.apache.logging.log4j.core.Filter;
025 import org.apache.logging.log4j.core.Layout;
026 import org.apache.logging.log4j.core.LogEvent;
027
028 /**
029 * Appends log events as bytes to a byte output stream. The stream encoding is defined in the layout.
030 *
031 * @param <M> The kind of {@link OutputStreamManager} under management
032 */
033 public abstract class AbstractOutputStreamAppender<M extends OutputStreamManager> extends AbstractAppender {
034
035 private static final long serialVersionUID = 1L;
036
037 /**
038 * Immediate flush means that the underlying writer or output stream
039 * will be flushed at the end of each append operation. Immediate
040 * flush is slower but ensures that each append request is actually
041 * written. If <code>immediateFlush</code> is set to
042 * {@code false}, then there is a good chance that the last few
043 * logs events are not actually written to persistent media if and
044 * when the application crashes.
045 */
046 protected final boolean immediateFlush;
047
048 private final M manager;
049
050 private final ReadWriteLock rwLock = new ReentrantReadWriteLock();
051 private final Lock readLock = rwLock.readLock();
052
053 /**
054 * Instantiate a WriterAppender and set the output destination to a
055 * new {@link java.io.OutputStreamWriter} initialized with <code>os</code>
056 * as its {@link java.io.OutputStream}.
057 * @param name The name of the Appender.
058 * @param layout The layout to format the message.
059 * @param manager The OutputStreamManager.
060 */
061 protected AbstractOutputStreamAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter,
062 final boolean ignoreExceptions, final boolean immediateFlush,
063 final M manager) {
064 super(name, filter, layout, ignoreExceptions);
065 this.manager = manager;
066 this.immediateFlush = immediateFlush;
067 }
068
069 /**
070 * Gets the manager.
071 *
072 * @return the manager.
073 */
074 public M getManager() {
075 return manager;
076 }
077
078 @Override
079 public void start() {
080 if (getLayout() == null) {
081 LOGGER.error("No layout set for the appender named [" + getName() + "].");
082 }
083 if (manager == null) {
084 LOGGER.error("No OutputStreamManager set for the appender named [" + getName() + "].");
085 }
086 super.start();
087 }
088
089 @Override
090 public void stop() {
091 super.stop();
092 manager.release();
093 }
094
095 /**
096 * Actual writing occurs here.
097 * <p>
098 * Most subclasses of <code>AbstractOutputStreamAppender</code> will need to override this method.
099 * </p>
100 *
101 * @param event
102 * The LogEvent.
103 */
104 @Override
105 public void append(final LogEvent event) {
106 readLock.lock();
107 try {
108 final byte[] bytes = getLayout().toByteArray(event);
109 if (bytes.length > 0) {
110 manager.write(bytes);
111 if (this.immediateFlush || event.isEndOfBatch()) {
112 manager.flush();
113 }
114 }
115 } catch (final AppenderLoggingException ex) {
116 error("Unable to write to stream " + manager.getName() + " for appender " + getName());
117 throw ex;
118 } finally {
119 readLock.unlock();
120 }
121 }
122 }