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.web;
18
19 import java.util.concurrent.locks.Lock;
20 import java.util.concurrent.locks.ReentrantLock;
21 import javax.servlet.ServletContext;
22
23 import org.apache.logging.log4j.LogManager;
24 import org.apache.logging.log4j.core.LoggerContext;
25 import org.apache.logging.log4j.core.impl.ContextAnchor;
26
27 /**
28 * Convenience methods for retrieving the {@link org.apache.logging.log4j.core.LoggerContext} associated with a
29 * particular ServletContext. These methods are most particularly useful for asynchronous servlets where the
30 * Thread Context ClassLoader (TCCL) is potentially different from the TCCL used by the
31 * Servlet container that bootstrapped Log4j.
32 *
33 * @since 2.0.1
34 */
35 public final class WebLoggerContextUtils {
36 private WebLoggerContextUtils() {
37 }
38
39 private static final Lock WEB_SUPPORT_LOOKUP = new ReentrantLock();
40
41 /**
42 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext.
43 *
44 * @param servletContext the ServletContext to locate a LoggerContext for
45 * @return the LoggerContext for the given ServletContext
46 * @since 2.0.1
47 */
48 public static LoggerContext getWebLoggerContext(final ServletContext servletContext) {
49 return (LoggerContext) servletContext.getAttribute(Log4jWebSupport.CONTEXT_ATTRIBUTE);
50 }
51
52 /**
53 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext.
54 *
55 * @param servletContext the ServletContext to locate a LoggerContext for
56 * @return the LoggerContext for the given ServletContext or {@code null} if none was set
57 * @throws java.lang.IllegalStateException if no LoggerContext could be found on the given ServletContext
58 * @since 2.0.1
59 */
60 public static LoggerContext getRequiredWebLoggerContext(final ServletContext servletContext) {
61 final LoggerContext loggerContext = getWebLoggerContext(servletContext);
62 if (loggerContext == null) {
63 throw new IllegalStateException(
64 "No LoggerContext found in ServletContext attribute " + Log4jWebSupport.CONTEXT_ATTRIBUTE);
65 }
66 return loggerContext;
67 }
68
69 /**
70 * Finds or initializes the {@link org.apache.logging.log4j.web.Log4jWebLifeCycle} singleton for the given
71 * ServletContext.
72 *
73 * @param servletContext the ServletContext to get the Log4jWebLifeCycle for
74 * @return the Log4jWebLifeCycle for the given ServletContext
75 * @since 2.0.1
76 */
77 public static Log4jWebLifeCycle getWebLifeCycle(final ServletContext servletContext) {
78 WEB_SUPPORT_LOOKUP.lock();
79 try {
80 Log4jWebLifeCycle webLifeCycle = (Log4jWebLifeCycle) servletContext.getAttribute(
81 Log4jWebSupport.SUPPORT_ATTRIBUTE);
82 if (webLifeCycle == null) {
83 webLifeCycle = Log4jWebInitializerImpl.initialize(servletContext);
84 }
85 return webLifeCycle;
86 } finally {
87 WEB_SUPPORT_LOOKUP.unlock();
88 }
89 }
90
91 /**
92 * Wraps a Runnable instance by setting its thread context {@link org.apache.logging.log4j.core.LoggerContext}
93 * before execution and clearing it after execution.
94 *
95 * @param servletContext the ServletContext to locate a LoggerContext for
96 * @param runnable the Runnable to wrap execution for
97 * @return a wrapped Runnable
98 * @since 2.0.1
99 */
100 public static Runnable wrapExecutionContext(final ServletContext servletContext, final Runnable runnable) {
101 return new Runnable() {
102 @Override
103 public void run() {
104 final Log4jWebSupport webSupport = getWebLifeCycle(servletContext);
105 webSupport.setLoggerContext();
106 try {
107 runnable.run();
108 } finally {
109 webSupport.clearLoggerContext();
110 }
111 }
112 };
113 }
114
115 /**
116 * Gets the current {@link ServletContext} if it has already been assigned to a LoggerContext's external context.
117 *
118 * @return the current ServletContext attached to a LoggerContext or {@code null} if none could be found
119 * @since 2.1
120 */
121 public static ServletContext getServletContext() {
122 org.apache.logging.log4j.spi.LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
123 if (lc == null) {
124 lc = LogManager.getContext(false);
125 }
126 return lc == null ? null :
127 lc.getExternalContext() instanceof ServletContext ? (ServletContext) lc.getExternalContext() : null;
128 }
129 }