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.spi;
18
19 import java.util.HashSet;
20 import java.util.Map;
21 import java.util.Set;
22 import java.util.WeakHashMap;
23 import java.util.concurrent.ConcurrentHashMap;
24 import java.util.concurrent.ConcurrentMap;
25 import java.util.concurrent.locks.ReadWriteLock;
26 import java.util.concurrent.locks.ReentrantReadWriteLock;
27
28 import org.apache.logging.log4j.LogManager;
29 import org.apache.logging.log4j.util.LoaderUtil;
30
31 /**
32 * Provides an abstract base class to use for implementing LoggerAdapter.
33 *
34 * @param <L> the Logger class to adapt
35 * @since 2.1
36 */
37 public abstract class AbstractLoggerAdapter<L> implements LoggerAdapter<L>, LoggerContextShutdownAware {
38
39 /**
40 * A map to store loggers for their given LoggerContexts.
41 */
42 protected final Map<LoggerContext, ConcurrentMap<String, L>> registry = new ConcurrentHashMap<>();
43
44 private final ReadWriteLock lock = new ReentrantReadWriteLock (true);
45
46 @Override
47 public L getLogger(final String name) {
48 final LoggerContext context = getContext();
49 final ConcurrentMap<String, L> loggers = getLoggersInContext(context);
50 final L logger = loggers.get(name);
51 if (logger != null) {
52 return logger;
53 }
54 loggers.putIfAbsent(name, newLogger(name, context));
55 return loggers.get(name);
56 }
57
58 @Override
59 public void contextShutdown(LoggerContext loggerContext) {
60 registry.remove(loggerContext);
61 }
62
63 /**
64 * Gets or creates the ConcurrentMap of named loggers for a given LoggerContext.
65 *
66 * @param context the LoggerContext to get loggers for
67 * @return the map of loggers for the given LoggerContext
68 */
69 public ConcurrentMap<String, L> getLoggersInContext(final LoggerContext context) {
70 ConcurrentMap<String, L> loggers;
71 lock.readLock ().lock ();
72 try {
73 loggers = registry.get (context);
74 } finally {
75 lock.readLock ().unlock ();
76 }
77
78 if (loggers != null) {
79 return loggers;
80 }
81 lock.writeLock ().lock ();
82 try {
83 loggers = registry.get (context);
84 if (loggers == null) {
85 loggers = new ConcurrentHashMap<> ();
86 registry.put (context, loggers);
87 if (context instanceof LoggerContextShutdownEnabled) {
88 ((LoggerContextShutdownEnabled) context).addShutdownListener(this);
89 }
90 }
91 return loggers;
92 } finally {
93 lock.writeLock ().unlock ();
94 }
95 }
96
97 /**
98 * For unit testing. Consider to be private.
99 */
100 public Set<LoggerContext> getLoggerContexts() {
101 return new HashSet<>(registry.keySet());
102 }
103
104 /**
105 * Creates a new named logger for a given {@link LoggerContext}.
106 *
107 * @param name the name of the logger to create
108 * @param context the LoggerContext this logger will be associated with
109 * @return the new named logger
110 */
111 protected abstract L newLogger(final String name, final LoggerContext context);
112
113 /**
114 * Gets the {@link LoggerContext} that should be used to look up or create loggers. This is similar in spirit to the
115 * {@code ContextSelector} class in {@code log4j-core}. However, implementations can rely on their own framework's
116 * separation of contexts instead (or simply use a singleton).
117 *
118 * @return the LoggerContext to be used for lookup and creation purposes
119 * @see org.apache.logging.log4j.LogManager#getContext(ClassLoader, boolean)
120 * @see org.apache.logging.log4j.LogManager#getContext(String, boolean)
121 */
122 protected abstract LoggerContext getContext();
123
124 /**
125 * Gets the {@link LoggerContext} associated with the given caller class.
126 *
127 * @param callerClass the caller class
128 * @return the LoggerContext for the calling class
129 */
130 protected LoggerContext getContext(final Class<?> callerClass) {
131 ClassLoader cl = null;
132 if (callerClass != null) {
133 cl = callerClass.getClassLoader();
134 }
135 if (cl == null) {
136 cl = LoaderUtil.getThreadContextClassLoader();
137 }
138 return LogManager.getContext(cl, false);
139 }
140
141 @Override
142 public void close() {
143 lock.writeLock ().lock ();
144 try {
145 registry.clear();
146 } finally {
147 lock.writeLock ().unlock ();
148 }
149 }
150 }