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.subject.support;
020
021 import org.apache.shiro.subject.Subject;
022 import org.apache.shiro.util.ThreadState;
023
024 /**
025 * A {@code SubjectRunnable} ensures that a target/delegate {@link Runnable Runnable} will execute such that any
026 * call to {@code SecurityUtils.}{@link org.apache.shiro.SecurityUtils#getSubject() getSubject()} during the
027 * {@code Runnable}'s execution will return the associated {@code Subject} instance. The {@code SubjectRunnable}
028 * instance can be run on any thread (the current thread or asynchronously on another thread) and the
029 * {@code SecurityUtils.getSubject()} call will still work properly. This implementation also guarantees that Shiro's
030 * thread state will be identical before and after execution to ensure threads remain clean in any thread-pooled
031 * environment.
032 * <p/>
033 * When instances of this class {@link Runnable#run() run()}, the following occurs:
034 * <ol>
035 * <li>The Subject and any of its associated thread state is first bound to the thread that executes the
036 * {@code Runnable}.</li>
037 * <li>The delegate/target {@code Runnable} is {@link #doRun(Runnable) run}</li>
038 * <li>Any previous thread state that might have existed before the {@code Subject} was bound is fully restored</li>
039 * </ol>
040 * <p/>
041 *
042 * <h3>Usage</h3>
043 *
044 * This is typically considered a support class and is not often directly referenced. Most people prefer to use
045 * the {@code Subject.}{@link Subject#execute(Runnable) execute} or
046 * {@code Subject.}{@link Subject#associateWith(Runnable) associateWith} methods, which transparently perform the
047 * necessary association logic.
048 * <p/>
049 * An even more convenient alternative is to use a
050 * {@link org.apache.shiro.concurrent.SubjectAwareExecutor SubjectAwareExecutor}, which transparently uses
051 * instances of this class but does not require referencing Shiro's API at all.
052 *
053 * @see Subject#associateWith(Runnable)
054 * @see org.apache.shiro.concurrent.SubjectAwareExecutor SubjectAwareExecutor
055 * @since 1.0
056 */
057 public class SubjectRunnable implements Runnable {
058
059 protected final ThreadState threadState;
060 private final Runnable runnable;
061
062 /**
063 * Creates a new {@code SubjectRunnable} that, when executed, will execute the target {@code delegate}, but
064 * guarantees that it will run associated with the specified {@code Subject}.
065 *
066 * @param subject the Subject to associate with the delegate's execution.
067 * @param delegate the runnable to run.
068 */
069 public SubjectRunnable(Subject subject, Runnable delegate) {
070 this(new SubjectThreadState(subject), delegate);
071 }
072
073 /**
074 * Creates a new {@code SubjectRunnable} that, when executed, will perform thread state
075 * {@link ThreadState#bind binding} and guaranteed {@link ThreadState#restore restoration} before and after the
076 * {@link Runnable Runnable}'s execution, respectively.
077 *
078 * @param threadState the thread state to bind and unbind before and after the runnable's execution.
079 * @param delegate the delegate {@code Runnable} to execute when this instance is {@link #run() run()}.
080 * @throws IllegalArgumentException if either the {@code ThreadState} or {@link Runnable} arguments are {@code null}.
081 */
082 protected SubjectRunnable(ThreadState threadState, Runnable delegate) throws IllegalArgumentException {
083 if (threadState == null) {
084 throw new IllegalArgumentException("ThreadState argument cannot be null.");
085 }
086 this.threadState = threadState;
087 if (delegate == null) {
088 throw new IllegalArgumentException("Runnable argument cannot be null.");
089 }
090 this.runnable = delegate;
091 }
092
093 /**
094 * {@link ThreadState#bind Bind}s the Subject thread state, executes the target {@code Runnable} and then guarantees
095 * the previous thread state's {@link ThreadState#restore restoration}:
096 * <pre>
097 * try {
098 * threadState.{@link ThreadState#bind bind()};
099 * {@link #doRun doRun}(targetRunnable);
100 * } finally {
101 * threadState.{@link ThreadState#restore restore()}
102 * }
103 * </pre>
104 */
105 public void run() {
106 try {
107 threadState.bind();
108 doRun(this.runnable);
109 } finally {
110 threadState.restore();
111 }
112 }
113
114 /**
115 * Simply calls the target {@link Runnable Runnable}'s {@link Runnable#run run()} method.
116 *
117 * @param runnable the target runnable to run.
118 */
119 protected void doRun(Runnable runnable) {
120 runnable.run();
121 }
122 }