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