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.AbstractMap;
20 import java.util.Map;
21 import java.util.concurrent.locks.Lock;
22 import java.util.concurrent.locks.ReentrantLock;
23 import jakarta.servlet.ServletContext;
24
25 import org.apache.logging.log4j.LogManager;
26 import org.apache.logging.log4j.core.LoggerContext;
27 import org.apache.logging.log4j.core.impl.ContextAnchor;
28
29 /**
30 * Convenience methods for retrieving the {@link org.apache.logging.log4j.core.LoggerContext} associated with a
31 * particular ServletContext. These methods are most particularly useful for asynchronous servlets where the
32 * Thread Context ClassLoader (TCCL) is potentially different from the TCCL used by the
33 * Servlet container that bootstrapped Log4j.
34 *
35 * @since 2.0.1
36 */
37 public final class WebLoggerContextUtils {
38 private WebLoggerContextUtils() {
39 }
40
41 private static final Lock WEB_SUPPORT_LOOKUP = new ReentrantLock();
42 private static final String SERVLET_CONTEXT = "__SERVLET_CONTEXT__";
43
44 /**
45 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext.
46 *
47 * @param servletContext the ServletContext to locate a LoggerContext for
48 * @return the LoggerContext for the given ServletContext
49 * @since 2.0.1
50 */
51 public static LoggerContext getWebLoggerContext(final ServletContext servletContext) {
52 return (LoggerContext) servletContext.getAttribute(Log4jWebSupport.CONTEXT_ATTRIBUTE);
53 }
54
55 /**
56 * Finds the main {@link org.apache.logging.log4j.core.LoggerContext} configured for the given ServletContext.
57 *
58 * @param servletContext the ServletContext to locate a LoggerContext for
59 * @return the LoggerContext for the given ServletContext or {@code null} if none was set
60 * @throws java.lang.IllegalStateException if no LoggerContext could be found on the given ServletContext
61 * @since 2.0.1
62 */
63 public static LoggerContext getRequiredWebLoggerContext(final ServletContext servletContext) {
64 final LoggerContext loggerContext = getWebLoggerContext(servletContext);
65 if (loggerContext == null) {
66 throw new IllegalStateException(
67 "No LoggerContext found in ServletContext attribute " + Log4jWebSupport.CONTEXT_ATTRIBUTE);
68 }
69 return loggerContext;
70 }
71
72 /**
73 * Finds or initializes the {@link org.apache.logging.log4j.web.Log4jWebLifeCycle} singleton for the given
74 * ServletContext.
75 *
76 * @param servletContext the ServletContext to get the Log4jWebLifeCycle for
77 * @return the Log4jWebLifeCycle for the given ServletContext
78 * @since 2.0.1
79 */
80 public static Log4jWebLifeCycle getWebLifeCycle(final ServletContext servletContext) {
81 WEB_SUPPORT_LOOKUP.lock();
82 try {
83 Log4jWebLifeCycle webLifeCycle = (Log4jWebLifeCycle) servletContext.getAttribute(
84 Log4jWebSupport.SUPPORT_ATTRIBUTE);
85 if (webLifeCycle == null) {
86 webLifeCycle = Log4jWebInitializerImpl.initialize(servletContext);
87 }
88 return webLifeCycle;
89 } finally {
90 WEB_SUPPORT_LOOKUP.unlock();
91 }
92 }
93
94 /**
95 * Wraps a Runnable instance by setting its thread context {@link org.apache.logging.log4j.core.LoggerContext}
96 * before execution and clearing it after execution.
97 *
98 * @param servletContext the ServletContext to locate a LoggerContext for
99 * @param runnable the Runnable to wrap execution for
100 * @return a wrapped Runnable
101 * @since 2.0.1
102 */
103 public static Runnable wrapExecutionContext(final ServletContext servletContext, final Runnable runnable) {
104 return () -> {
105 final Log4jWebSupport webSupport = getWebLifeCycle(servletContext);
106 webSupport.setLoggerContext();
107 try {
108 runnable.run();
109 } finally {
110 webSupport.clearLoggerContext();
111 }
112 };
113 }
114
115 public static Map.Entry<String, Object> createExternalEntry(ServletContext servletContext) {
116 return new AbstractMap.SimpleEntry<>(SERVLET_CONTEXT, servletContext);
117 }
118
119 public static void setServletContext(LoggerContext lc, ServletContext servletContext) {
120 if (lc != null) {
121 lc.putObject(SERVLET_CONTEXT, servletContext);
122 }
123 }
124
125 /**
126 * Gets the current {@link ServletContext} if it has already been assigned to a LoggerContext's external context.
127 *
128 * @return the current ServletContext attached to a LoggerContext or {@code null} if none could be found
129 * @since 2.1
130 */
131 public static ServletContext getServletContext() {
132 org.apache.logging.log4j.spi.LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
133 if (lc == null) {
134 lc = LogManager.getContext(false);
135 }
136
137 Object obj = lc != null ? lc.getObject(SERVLET_CONTEXT) : null;
138 if (obj instanceof ServletContext) {
139 return (ServletContext) obj;
140 }
141 return null;
142 }
143 }