1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache license, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the license for the specific language governing permissions and
15 * limitations under the license.
16 */
17 package org.apache.logging.log4j.core.appender;
18
19 import java.util.concurrent.TimeUnit;
20 import java.util.concurrent.locks.Lock;
21 import java.util.concurrent.locks.ReadWriteLock;
22 import java.util.concurrent.locks.ReentrantReadWriteLock;
23
24 import org.apache.logging.log4j.core.Filter;
25 import org.apache.logging.log4j.core.LogEvent;
26 import org.apache.logging.log4j.core.StringLayout;
27
28 /**
29 * Appends log events as strings to a writer.
30 *
31 * @param <M>
32 * The kind of {@link WriterManager} under management
33 */
34 public abstract class AbstractWriterAppender<M extends WriterManager> extends AbstractAppender {
35
36 /**
37 * Immediate flush means that the underlying writer will be flushed at the
38 * end of each append operation. Immediate flush is slower but ensures that
39 * each append request is actually written. If <code>immediateFlush</code>
40 * is set to {@code false}, then there is a good chance that the last few
41 * logs events are not actually written to persistent media if and when the
42 * application crashes.
43 */
44 protected final boolean immediateFlush;
45 private final M manager;
46 private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
47 private final Lock readLock = readWriteLock.readLock();
48
49 /**
50 * Instantiates.
51 *
52 * @param name
53 * The name of the Appender.
54 * @param layout
55 * The layout to format the message.
56 * @param manager
57 * The OutputStreamManager.
58 */
59 protected AbstractWriterAppender(final String name, final StringLayout layout, final Filter filter,
60 final boolean ignoreExceptions, final boolean immediateFlush, final M manager) {
61 super(name, filter, layout, ignoreExceptions);
62 this.manager = manager;
63 this.immediateFlush = immediateFlush;
64 }
65
66 /**
67 * Actual writing occurs here.
68 * <p>
69 * Most subclasses will need to override this method.
70 * </p>
71 *
72 * @param event
73 * The LogEvent.
74 */
75 @Override
76 public void append(final LogEvent event) {
77 readLock.lock();
78 try {
79 final String str = getStringLayout().toSerializable(event);
80 if (str.length() > 0) {
81 manager.write(str);
82 if (this.immediateFlush || event.isEndOfBatch()) {
83 manager.flush();
84 }
85 }
86 } catch (final AppenderLoggingException ex) {
87 error("Unable to write " + manager.getName() + " for appender " + getName() + ": " + ex);
88 throw ex;
89 } finally {
90 readLock.unlock();
91 }
92 }
93
94 /**
95 * Gets the manager.
96 *
97 * @return the manager.
98 */
99 public M getManager() {
100 return manager;
101 }
102
103 public StringLayout getStringLayout() {
104 return (StringLayout) getLayout();
105 }
106
107 @Override
108 public void start() {
109 if (getLayout() == null) {
110 LOGGER.error("No layout set for the appender named [{}].", getName());
111 }
112 if (manager == null) {
113 LOGGER.error("No OutputStreamManager set for the appender named [{}].", getName());
114 }
115 super.start();
116 }
117
118 @Override
119 public boolean stop(final long timeout, final TimeUnit timeUnit) {
120 setStopping();
121 boolean stopped = super.stop(timeout, timeUnit, false);
122 stopped &= manager.stop(timeout, timeUnit);
123 setStopped();
124 return stopped;
125 }
126 }