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.io.IOException;
20 import java.io.Writer;
21
22 import org.apache.logging.log4j.core.StringLayout;
23
24 /**
25 * Manages a Writer so that it can be shared by multiple Appenders and will
26 * allow appenders to reconfigure without requiring a new writer.
27 */
28 public class WriterManager extends AbstractManager {
29
30 /**
31 * Creates a Manager.
32 *
33 * @param name The name of the stream to manage.
34 * @param data The data to pass to the Manager.
35 * @param factory The factory to use to create the Manager.
36 * @param <T> The type of the WriterManager.
37 * @return A WriterManager.
38 */
39 public static <T> WriterManager getManager(final String name, final T data,
40 final ManagerFactory<? extends WriterManager, T> factory) {
41 return AbstractManager.getManager(name, factory, data);
42 }
43 protected final StringLayout layout;
44
45 private volatile Writer writer;
46
47 public WriterManager(final Writer writer, final String streamName, final StringLayout layout,
48 final boolean writeHeader) {
49 super(streamName);
50 this.writer = writer;
51 this.layout = layout;
52 if (writeHeader && layout != null) {
53 final byte[] header = layout.getHeader();
54 if (header != null) {
55 try {
56 this.writer.write(new String(header, layout.getCharset()));
57 } catch (final IOException e) {
58 logError("Unable to write header", e);
59 }
60 }
61 }
62 }
63
64 protected synchronized void close() {
65 final Writer w = writer; // access volatile field only once per method
66 try {
67 w.close();
68 } catch (final IOException ex) {
69 logError("Unable to close stream", ex);
70 }
71 }
72
73 /**
74 * Flushes any buffers.
75 */
76 public synchronized void flush() {
77 try {
78 writer.flush();
79 } catch (final IOException ex) {
80 final String msg = "Error flushing stream " + getName();
81 throw new AppenderLoggingException(msg, ex);
82 }
83 }
84
85 protected Writer getWriter() {
86 return writer;
87 }
88
89 /**
90 * Returns the status of the stream.
91 * @return true if the stream is open, false if it is not.
92 */
93 public boolean isOpen() {
94 return getCount() > 0;
95 }
96
97 /**
98 * Default hook to write footer during close.
99 */
100 @Override
101 public void releaseSub() {
102 writeFooter();
103 close();
104 }
105
106 protected void setWriter(final Writer writer) {
107 final byte[] header = layout.getHeader();
108 if (header != null) {
109 try {
110 writer.write(new String(header, layout.getCharset()));
111 this.writer = writer; // only update field if writer.write() succeeded
112 } catch (final IOException ioe) {
113 logError("Unable to write header", ioe);
114 }
115 } else {
116 this.writer = writer;
117 }
118 }
119
120 /**
121 * Some output streams synchronize writes while others do not. Synchronizing here insures that
122 * log events won't be intertwined.
123 * @param bytes The serialized Log event.
124 * @param offset The offset into the byte array.
125 * @param length The number of bytes to write.
126 * @throws AppenderLoggingException if an error occurs.
127 */
128 protected synchronized void write(final String str) {
129 try {
130 writer.write(str);
131 } catch (final IOException ex) {
132 final String msg = "Error writing to stream " + getName();
133 throw new AppenderLoggingException(msg, ex);
134 }
135 }
136
137 /**
138 * Writes the footer.
139 */
140 protected void writeFooter() {
141 if (layout == null) {
142 return;
143 }
144 final byte[] footer = layout.getFooter();
145 if (footer != null && footer.length > 0) {
146 write(new String(footer, layout.getCharset()));
147 }
148 }
149 }