001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied. See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019 package org.apache.shiro.util;
020
021 import org.apache.shiro.mgt.SecurityManager;
022 import org.apache.shiro.subject.Subject;
023 import org.slf4j.Logger;
024 import org.slf4j.LoggerFactory;
025
026 import java.util.HashMap;
027 import java.util.Map;
028
029
030 /**
031 * A ThreadContext provides a means of binding and unbinding objects to the
032 * current thread based on key/value pairs.
033 * <p/>
034 * <p>An internal {@link java.util.HashMap} is used to maintain the key/value pairs
035 * for each thread.</p>
036 * <p/>
037 * <p>If the desired behavior is to ensure that bound data is not shared across
038 * threads in a pooled or reusable threaded environment, the application (or more likely a framework) must
039 * bind and remove any necessary values at the beginning and end of stack
040 * execution, respectively (i.e. individually explicitly or all via the <tt>clear</tt> method).</p>
041 *
042 * @see #remove()
043 * @since 0.1
044 */
045 public abstract class ThreadContext {
046
047 /**
048 * Private internal log instance.
049 */
050 private static final Logger log = LoggerFactory.getLogger(ThreadContext.class);
051
052 public static final String SECURITY_MANAGER_KEY = ThreadContext.class.getName() + "_SECURITY_MANAGER_KEY";
053 public static final String SUBJECT_KEY = ThreadContext.class.getName() + "_SUBJECT_KEY";
054
055 private static final ThreadLocal<Map<Object, Object>> resources = new InheritableThreadLocalMap<Map<Object, Object>>();
056
057 /**
058 * Default no-argument constructor.
059 */
060 protected ThreadContext() {
061 }
062
063 /**
064 * Returns the ThreadLocal Map. This Map is used internally to bind objects
065 * to the current thread by storing each object under a unique key.
066 *
067 * @return the map of bound resources
068 */
069 public static Map<Object, Object> getResources() {
070 return resources != null ? new HashMap<Object, Object>(resources.get()) : null;
071 }
072
073 /**
074 * Allows a caller to explicitly set the entire resource map. This operation overwrites everything that existed
075 * previously in the ThreadContext - if you need to retain what was on the thread prior to calling this method,
076 * call the {@link #getResources()} method, which will give you the existing state.
077 *
078 * @param newResources the resources to replace the existing {@link #getResources() resources}.
079 * @since 1.0
080 */
081 public static void setResources(Map<Object, Object> newResources) {
082 if (CollectionUtils.isEmpty(newResources)) {
083 return;
084 }
085 resources.get().clear();
086 resources.get().putAll(newResources);
087 }
088
089 /**
090 * Returns the value bound in the {@code ThreadContext} under the specified {@code key}, or {@code null} if there
091 * is no value for that {@code key}.
092 *
093 * @param key the map key to use to lookup the value
094 * @return the value bound in the {@code ThreadContext} under the specified {@code key}, or {@code null} if there
095 * is no value for that {@code key}.
096 * @since 1.0
097 */
098 private static Object getValue(Object key) {
099 return resources.get().get(key);
100 }
101
102 /**
103 * Returns the object for the specified <code>key</code> that is bound to
104 * the current thread.
105 *
106 * @param key the key that identifies the value to return
107 * @return the object keyed by <code>key</code> or <code>null</code> if
108 * no value exists for the specified <code>key</code>
109 */
110 public static Object get(Object key) {
111 if (log.isTraceEnabled()) {
112 String msg = "get() - in thread [" + Thread.currentThread().getName() + "]";
113 log.trace(msg);
114 }
115
116 Object value = getValue(key);
117 if ((value != null) && log.isTraceEnabled()) {
118 String msg = "Retrieved value of type [" + value.getClass().getName() + "] for key [" +
119 key + "] " + "bound to thread [" + Thread.currentThread().getName() + "]";
120 log.trace(msg);
121 }
122 return value;
123 }
124
125 /**
126 * Binds <tt>value</tt> for the given <code>key</code> to the current thread.
127 * <p/>
128 * <p>A <tt>null</tt> <tt>value</tt> has the same effect as if <tt>remove</tt> was called for the given
129 * <tt>key</tt>, i.e.:
130 * <p/>
131 * <pre>
132 * if ( value == null ) {
133 * remove( key );
134 * }</pre>
135 *
136 * @param key The key with which to identify the <code>value</code>.
137 * @param value The value to bind to the thread.
138 * @throws IllegalArgumentException if the <code>key</code> argument is <tt>null</tt>.
139 */
140 public static void put(Object key, Object value) {
141 if (key == null) {
142 throw new IllegalArgumentException("key cannot be null");
143 }
144
145 if (value == null) {
146 remove(key);
147 return;
148 }
149
150 resources.get().put(key, value);
151
152 if (log.isTraceEnabled()) {
153 String msg = "Bound value of type [" + value.getClass().getName() + "] for key [" +
154 key + "] to thread " + "[" + Thread.currentThread().getName() + "]";
155 log.trace(msg);
156 }
157 }
158
159 /**
160 * Unbinds the value for the given <code>key</code> from the current
161 * thread.
162 *
163 * @param key The key identifying the value bound to the current thread.
164 * @return the object unbound or <tt>null</tt> if there was nothing bound
165 * under the specified <tt>key</tt> name.
166 */
167 public static Object remove(Object key) {
168 Object value = resources.get().remove(key);
169
170 if ((value != null) && log.isTraceEnabled()) {
171 String msg = "Removed value of type [" + value.getClass().getName() + "] for key [" +
172 key + "]" + "from thread [" + Thread.currentThread().getName() + "]";
173 log.trace(msg);
174 }
175
176 return value;
177 }
178
179 /**
180 * {@link ThreadLocal#remove Remove}s the underlying {@link ThreadLocal ThreadLocal} from the thread.
181 * <p/>
182 * This method is meant to be the final 'clean up' operation that is called at the end of thread execution to
183 * prevent thread corruption in pooled thread environments.
184 *
185 * @since 1.0
186 */
187 public static void remove() {
188 resources.remove();
189 }
190
191 /**
192 * Convenience method that simplifies retrieval of the application's SecurityManager instance from the current
193 * thread. If there is no SecurityManager bound to the thread (probably because framework code did not bind it
194 * to the thread), this method returns <tt>null</tt>.
195 * <p/>
196 * It is merely a convenient wrapper for the following:
197 * <p/>
198 * <code>return (SecurityManager)get( SECURITY_MANAGER_KEY );</code>
199 * <p/>
200 * This method only returns the bound value if it exists - it does not remove it
201 * from the thread. To remove it, one must call {@link #unbindSecurityManager() unbindSecurityManager()} instead.
202 *
203 * @return the Subject object bound to the thread, or <tt>null</tt> if there isn't one bound.
204 * @since 0.9
205 */
206 public static SecurityManager getSecurityManager() {
207 return (SecurityManager) get(SECURITY_MANAGER_KEY);
208 }
209
210
211 /**
212 * Convenience method that simplifies binding the application's SecurityManager instance to the ThreadContext.
213 * <p/>
214 * <p>The method's existence is to help reduce casting in code and to simplify remembering of
215 * ThreadContext key names. The implementation is simple in that, if the SecurityManager is not <tt>null</tt>,
216 * it binds it to the thread, i.e.:
217 * <p/>
218 * <pre>
219 * if (securityManager != null) {
220 * put( SECURITY_MANAGER_KEY, securityManager);
221 * }</pre>
222 *
223 * @param securityManager the application's SecurityManager instance to bind to the thread. If the argument is
224 * null, nothing will be done.
225 * @since 0.9
226 */
227 public static void bind(SecurityManager securityManager) {
228 if (securityManager != null) {
229 put(SECURITY_MANAGER_KEY, securityManager);
230 }
231 }
232
233 /**
234 * Convenience method that simplifies removal of the application's SecurityManager instance from the thread.
235 * <p/>
236 * The implementation just helps reduce casting and remembering of the ThreadContext key name, i.e it is
237 * merely a conveient wrapper for the following:
238 * <p/>
239 * <code>return (SecurityManager)remove( SECURITY_MANAGER_KEY );</code>
240 * <p/>
241 * If you wish to just retrieve the object from the thread without removing it (so it can be retrieved later
242 * during thread execution), use the {@link #getSecurityManager() getSecurityManager()} method instead.
243 *
244 * @return the application's SecurityManager instance previously bound to the thread, or <tt>null</tt> if there
245 * was none bound.
246 * @since 0.9
247 */
248 public static SecurityManager unbindSecurityManager() {
249 return (SecurityManager) remove(SECURITY_MANAGER_KEY);
250 }
251
252 /**
253 * Convenience method that simplifies retrieval of a thread-bound Subject. If there is no
254 * Subject bound to the thread, this method returns <tt>null</tt>. It is merely a convenient wrapper
255 * for the following:
256 * <p/>
257 * <code>return (Subject)get( SUBJECT_KEY );</code>
258 * <p/>
259 * This method only returns the bound value if it exists - it does not remove it
260 * from the thread. To remove it, one must call {@link #unbindSubject() unbindSubject()} instead.
261 *
262 * @return the Subject object bound to the thread, or <tt>null</tt> if there isn't one bound.
263 * @since 0.2
264 */
265 public static Subject getSubject() {
266 return (Subject) get(SUBJECT_KEY);
267 }
268
269
270 /**
271 * Convenience method that simplifies binding a Subject to the ThreadContext.
272 * <p/>
273 * <p>The method's existence is to help reduce casting in your own code and to simplify remembering of
274 * ThreadContext key names. The implementation is simple in that, if the Subject is not <tt>null</tt>,
275 * it binds it to the thread, i.e.:
276 * <p/>
277 * <pre>
278 * if (subject != null) {
279 * put( SUBJECT_KEY, subject );
280 * }</pre>
281 *
282 * @param subject the Subject object to bind to the thread. If the argument is null, nothing will be done.
283 * @since 0.2
284 */
285 public static void bind(Subject subject) {
286 if (subject != null) {
287 put(SUBJECT_KEY, subject);
288 }
289 }
290
291 /**
292 * Convenience method that simplifies removal of a thread-local Subject from the thread.
293 * <p/>
294 * The implementation just helps reduce casting and remembering of the ThreadContext key name, i.e it is
295 * merely a conveient wrapper for the following:
296 * <p/>
297 * <code>return (Subject)remove( SUBJECT_KEY );</code>
298 * <p/>
299 * If you wish to just retrieve the object from the thread without removing it (so it can be retrieved later during
300 * thread execution), you should use the {@link #getSubject() getSubject()} method for that purpose.
301 *
302 * @return the Subject object previously bound to the thread, or <tt>null</tt> if there was none bound.
303 * @since 0.2
304 */
305 public static Subject unbindSubject() {
306 return (Subject) remove(SUBJECT_KEY);
307 }
308
309 private static final class InheritableThreadLocalMap<T extends Map<Object, Object>> extends InheritableThreadLocal<Map<Object, Object>> {
310 protected Map<Object, Object> initialValue() {
311 return new HashMap<Object, Object>();
312 }
313
314 /**
315 * This implementation was added to address a
316 * <a href="http://jsecurity.markmail.org/search/?q=#query:+page:1+mid:xqi2yxurwmrpqrvj+state:results">
317 * user-reported issue</a>.
318 * @param parentValue the parent value, a HashMap as defined in the {@link #initialValue()} method.
319 * @return the HashMap to be used by any parent-spawned child threads (a clone of the parent HashMap).
320 */
321 @SuppressWarnings({"unchecked"})
322 protected Map<Object, Object> childValue(Map<Object, Object> parentValue) {
323 if (parentValue != null) {
324 return (Map<Object, Object>) ((HashMap<Object, Object>) parentValue).clone();
325 } else {
326 return null;
327 }
328 }
329 }
330 }
331