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1   /*
2    * $Id: ExecuteAndWaitInterceptor.java 651946 2008-04-27 13:41:38Z apetrelli $
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  package org.apache.struts2.interceptor;
23  
24  import java.util.Collections;
25  import java.util.Map;
26  
27  import com.opensymphony.xwork2.ActionContext;
28  import com.opensymphony.xwork2.ActionInvocation;
29  import com.opensymphony.xwork2.ActionProxy;
30  import com.opensymphony.xwork2.config.entities.ResultConfig;
31  import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
32  import com.opensymphony.xwork2.util.logging.Logger;
33  import com.opensymphony.xwork2.util.logging.LoggerFactory;
34  import org.apache.struts2.util.TokenHelper;
35  
36  
37  /***
38   * <!-- START SNIPPET: description -->
39   *
40   * The ExecuteAndWaitInterceptor is great for running long-lived actions in the background while showing the user a nice
41   * progress meter. This also prevents the HTTP request from timing out when the action takes more than 5 or 10 minutes.
42   *
43   * <p/> Using this interceptor is pretty straight forward. Assuming that you are including struts-default.xml, this
44   * interceptor is already configured but is not part of any of the default stacks. Because of the nature of this
45   * interceptor, it must be the <b>last</b> interceptor in the stack.
46   *
47   * <p/> This interceptor works on a per-session basis. That means that the same action name (myLongRunningAction, in the
48   * above example) cannot be run more than once at a time in a given session. On the initial request or any subsequent
49   * requests (before the action has completed), the <b>wait</b> result will be returned. <b>The wait result is
50   * responsible for issuing a subsequent request back to the action, giving the effect of a self-updating progress
51   * meter</b>.
52   *
53   * <p/> If no "wait" result is found, Struts will automatically generate a wait result on the fly. This result is
54   * written in FreeMarker and cannot run unless FreeMarker is installed. If you don't wish to deploy with FreeMarker, you
55   * must provide your own wait result. This is generally a good thing to do anyway, as the default wait page is very
56   * plain.
57   *
58   * <p/>Whenever the wait result is returned, the <b>action that is currently running in the background will be placed on
59   * top of the stack</b>. This allows you to display progress data, such as a count, in the wait page. By making the wait
60   * page automatically reload the request to the action (which will be short-circuited by the interceptor), you can give
61   * the appearance of an automatic progress meter.
62   *
63   * <p/>This interceptor also supports using an initial wait delay. An initial delay is a time in milliseconds we let the
64   * server wait before the wait page is shown to the user. During the wait this interceptor will wake every 100 millis
65   * to check if the background process is done premature, thus if the job for some reason doesn't take to long the wait
66   * page is not shown to the user.
67   * <br/> This is useful for e.g. search actions that have a wide span of execution time. Using a delay time of 2000
68   * millis we ensure the user is presented fast search results immediately and for the slow results a wait page is used.
69   *
70   * <p/><b>Important</b>: Because the action will be running in a seperate thread, you can't use ActionContext because it
71   * is a ThreadLocal. This means if you need to access, for example, session data, you need to implement SessionAware
72   * rather than calling ActionContext.getSession().
73   *
74   * <p/>The thread kicked off by this interceptor will be named in the form <b><u>actionName</u>BackgroundProcess</b>.
75   * For example, the <i>search</i> action would run as a thread named <i>searchBackgroundProcess</i>.
76   *
77   * <!-- END SNIPPET: description -->
78   *
79   * <p/> <u>Interceptor parameters:</u>
80   *
81   * <!-- START SNIPPET: parameters -->
82   *
83   * <ul>
84   *
85   * <li>threadPriority (optional) - the priority to assign the thread. Default is <code>Thread.NORM_PRIORITY</code>.</li>
86   * <li>delay (optional) - an initial delay in millis to wait before the wait page is shown (returning <code>wait</code> as result code). Default is no initial delay.</li>
87   * <li>delaySleepInterval (optional) - only used with delay. Used for waking up at certain intervals to check if the background process is already done. Default is 100 millis.</li>
88   *
89   * </ul>
90   *
91   * <!-- END SNIPPET: parameters -->
92   *
93   * <p/> <u>Extending the interceptor:</u>
94   *
95   * <p/>
96   *
97   * <!-- START SNIPPET: extending -->
98   *
99   * If you wish to make special preparations before and/or after the invocation of the background thread, you can extend
100  * the BackgroundProcess class and implement the beforeInvocation() and afterInvocation() methods. This may be useful
101  * for obtaining and releasing resources that the background process will need to execute successfully. To use your
102  * background process extension, extend ExecuteAndWaitInterceptor and implement the getNewBackgroundProcess() method.
103  *
104  * <!-- END SNIPPET: extending -->
105  *
106  * <p/> <u>Example code:</u>
107  *
108  * <pre>
109  * <!-- START SNIPPET: example -->
110  * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
111  *     &lt;interceptor-ref name="completeStack"/&gt;
112  *     &lt;interceptor-ref name="execAndWait"/&gt;
113  *     &lt;result name="wait"&gt;longRunningAction-wait.jsp&lt;/result&gt;
114  *     &lt;result name="success"&gt;longRunningAction-success.jsp&lt;/result&gt;
115  * &lt;/action&gt;
116  *
117  * &lt;%@ taglib prefix="s" uri="/struts" %&gt;
118  * &lt;html&gt;
119  *   &lt;head&gt;
120  *     &lt;title&gt;Please wait&lt;/title&gt;
121  *     &lt;meta http-equiv="refresh" content="5;url=&lt;s:url includeParams="all" /&gt;"/&gt;
122  *   &lt;/head&gt;
123  *   &lt;body&gt;
124  *     Please wait while we process your request.
125  *     Click &lt;a href="&lt;s:url includeParams="all" /&gt;">&lt;/a&gt; if this page does not reload automatically.
126  *   &lt;/body&gt;
127  * &lt;/html&gt;
128  * </pre>
129  *
130  * <p/> <u>Example code2:</u>
131  * This example will wait 2 second (2000 millis) before the wait page is shown to the user. Therefore
132  * if the long process didn't last long anyway the user isn't shown a wait page.
133  *
134  * <pre>
135  * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
136  *     &lt;interceptor-ref name="completeStack"/&gt;
137  *     &lt;interceptor-ref name="execAndWait"&gt;
138  *         &lt;param name="delay"&gt;2000&lt;param&gt;
139  *     &lt;interceptor-ref&gt;
140  *     &lt;result name="wait"&gt;longRunningAction-wait.jsp&lt;/result&gt;
141  *     &lt;result name="success"&gt;longRunningAction-success.jsp&lt;/result&gt;
142  * &lt;/action&gt;
143  * </pre>
144  *
145  * <p/> <u>Example code3:</u>
146  * This example will wait 1 second (1000 millis) before the wait page is shown to the user.
147  * And at every 50 millis this interceptor will check if the background process is done, if so
148  * it will return before the 1 second has elapsed, and the user isn't shown a wait page.
149  *
150  * <pre>
151  * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
152  *     &lt;interceptor-ref name="completeStack"/&gt;
153  *     &lt;interceptor-ref name="execAndWait"&gt;
154  *         &lt;param name="delay"&gt;1000&lt;param&gt;
155  *         &lt;param name="delaySleepInterval"&gt;50&lt;param&gt;
156  *     &lt;interceptor-ref&gt;
157  *     &lt;result name="wait"&gt;longRunningAction-wait.jsp&lt;/result&gt;
158  *     &lt;result name="success"&gt;longRunningAction-success.jsp&lt;/result&gt;
159  * &lt;/action&gt;
160  * </pre>
161  *
162  * <!-- END SNIPPET: example -->
163  *
164  */
165 public class ExecuteAndWaitInterceptor extends MethodFilterInterceptor {
166 
167     private static final long serialVersionUID = -2754639196749652512L;
168 
169     private static final Logger LOG = LoggerFactory.getLogger(ExecuteAndWaitInterceptor.class);
170 
171     public static final String KEY = "__execWait";
172     public static final String WAIT = "wait";
173     protected int delay;
174     protected int delaySleepInterval = 100; // default sleep 100 millis before checking if background process is done
175     protected boolean executeAfterValidationPass = false;
176 
177     private int threadPriority = Thread.NORM_PRIORITY;
178 
179     /* (non-Javadoc)
180      * @see com.opensymphony.xwork2.interceptor.Interceptor#init()
181      */
182     public void init() {
183     }
184 
185     /***
186      * Creates a new background process
187      *
188      * @param name The process name
189      * @param actionInvocation The action invocation
190      * @param threadPriority The thread priority
191      * @return The new process
192      */
193     protected BackgroundProcess getNewBackgroundProcess(String name, ActionInvocation actionInvocation, int threadPriority) {
194         return new BackgroundProcess(name + "BackgroundThread", actionInvocation, threadPriority);
195     }
196 
197     /***
198      * Returns the name to associate the background process.  Override to change the way background processes
199      * are mapped to requests.
200      *
201      * @return the name of the background thread
202      */
203     protected String getBackgroundProcessName(ActionProxy proxy) {
204         return proxy.getActionName();
205     }
206 
207     /* (non-Javadoc)
208      * @see com.opensymphony.xwork2.interceptor.MethodFilterInterceptor#doIntercept(com.opensymphony.xwork2.ActionInvocation)
209      */
210     protected String doIntercept(ActionInvocation actionInvocation) throws Exception {
211         ActionProxy proxy = actionInvocation.getProxy();
212         String name = getBackgroundProcessName(proxy);
213         ActionContext context = actionInvocation.getInvocationContext();
214         Map session = context.getSession();
215 
216         Boolean secondTime  = true;
217         if (executeAfterValidationPass) {
218             secondTime = (Boolean) context.get(KEY);
219             if (secondTime == null) {
220                 context.put(KEY, true);
221                 secondTime = false;
222             } else {
223                 secondTime = true;
224                 context.put(KEY, null);
225             }
226         }
227 
228         synchronized (session) {
229             BackgroundProcess bp = (BackgroundProcess) session.get(KEY + name);
230 
231             if ((!executeAfterValidationPass || secondTime) && bp == null) {
232                 bp = getNewBackgroundProcess(name, actionInvocation, threadPriority);
233                 session.put(KEY + name, bp);
234                 performInitialDelay(bp); // first time let some time pass before showing wait page
235                 secondTime = false;
236             }
237 
238             if ((!executeAfterValidationPass || !secondTime) && bp != null && !bp.isDone()) {
239                 actionInvocation.getStack().push(bp.getAction());
240                 Map results = proxy.getConfig().getResults();
241                 if (!results.containsKey(WAIT)) {
242                     LOG.warn("ExecuteAndWait interceptor has detected that no result named 'wait' is available. " +
243                             "Defaulting to a plain built-in wait page. It is highly recommend you " +
244                             "provide an action-specific or global result named '" + WAIT +
245                             "'! This requires FreeMarker support and won't work if you don't have it installed");
246                     // no wait result? hmm -- let's try to do dynamically put it in for you!
247                     ResultConfig rc = new ResultConfig.Builder(WAIT, "org.apache.struts2.views.freemarker.FreemarkerResult")
248                             .addParams(Collections.singletonMap("location", "/org/apache/struts2/interceptor/wait.ftl"))
249                             .build();
250                     results.put(WAIT, rc);
251                 }
252 
253                 if (TokenHelper.getToken() != null) {
254                     session.put(TokenHelper.getTokenName(), TokenHelper.getToken());
255                 }
256 
257                 return WAIT;
258             } else if ((!executeAfterValidationPass || !secondTime) && bp != null && bp.isDone()) {
259                 session.remove(KEY + name);
260                 actionInvocation.getStack().push(bp.getAction());
261 
262                 // if an exception occured during action execution, throw it here
263                 if (bp.getException() != null) {
264                     throw bp.getException();
265                 }
266 
267                 return bp.getResult();
268             } else {
269                 // this is the first instance of the interceptor and there is no existing action
270                 // already run in the background, so let's just let this pass through. We assume
271                 // the action invocation will be run in the background on the subsequent pass through
272                 // this interceptor
273                 return actionInvocation.invoke();
274             }
275         }
276     }
277 
278 
279     /* (non-Javadoc)
280      * @see com.opensymphony.xwork2.interceptor.Interceptor#destroy()
281      */
282     public void destroy() {
283     }
284 
285     /***
286      * Performs the initial delay.
287      * <p/>
288      * When this interceptor is executed for the first time this methods handles any provided initial delay.
289      * An initial delay is a time in miliseconds we let the server wait before we continue.
290      * <br/> During the wait this interceptor will wake every 100 millis to check if the background
291      * process is done premature, thus if the job for some reason doesn't take to long the wait
292      * page is not shown to the user.
293      *
294      * @param bp the background process
295      * @throws InterruptedException is thrown by Thread.sleep
296      */
297     protected void performInitialDelay(BackgroundProcess bp) throws InterruptedException {
298         if (delay <= 0 || delaySleepInterval <= 0) {
299             return;
300         }
301 
302         int steps = delay / delaySleepInterval;
303         if (LOG.isDebugEnabled()) {
304             LOG.debug("Delaying for " + delay + " millis. (using " + steps + " steps)");
305         }
306         int step;
307         for (step = 0; step < steps && !bp.isDone(); step++) {
308             Thread.sleep(delaySleepInterval);
309         }
310         if (LOG.isDebugEnabled()) {
311             LOG.debug("Sleeping ended after " + step + " steps and the background process is " + (bp.isDone() ? " done" : " not done"));
312         }
313     }
314 
315     /***
316      * Sets the thread priority of the background process.
317      *
318      * @param threadPriority the priority from <code>Thread.XXX</code>
319      */
320     public void setThreadPriority(int threadPriority) {
321         this.threadPriority = threadPriority;
322     }
323 
324     /***
325      * Sets the initial delay in millis (msec).
326      *
327      * @param delay in millis. (0 for not used)
328      */
329     public void setDelay(int delay) {
330         this.delay = delay;
331     }
332 
333     /***
334      * Sets the sleep interval in millis (msec) when performing the initial delay.
335      *
336      * @param delaySleepInterval in millis (0 for not used)
337      */
338     public void setDelaySleepInterval(int delaySleepInterval) {
339         this.delaySleepInterval = delaySleepInterval;
340     }
341 
342     /***
343      * Whether to start the background process after the second pass (first being validation)
344      * or not
345      *
346      * @param executeAfterValidationPass the executeAfterValidationPass to set
347      */
348     public void setExecuteAfterValidationPass(boolean executeAfterValidationPass) {
349         this.executeAfterValidationPass = executeAfterValidationPass;
350     }
351 
352 
353 }