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Java > Open Source Codes > org > quartz > plugins > SchedulerPluginWithUserTransactionSupport


1 /*
2  * Copyright 2004-2006 OpenSymphony
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
5  * use this file except in compliance with the License. You may obtain a copy
6  * of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13  * License for the specific language governing permissions and limitations
14  * under the License.
15  */
16 package org.quartz.plugins;
17
18 import javax.transaction.Status JavaDoc;
19 import javax.transaction.UserTransaction JavaDoc;
20
21 import org.apache.commons.logging.Log;
22 import org.apache.commons.logging.LogFactory;
23 import org.quartz.Scheduler;
24 import org.quartz.SchedulerException;
25 import org.quartz.ee.jta.UserTransactionHelper;
26 import org.quartz.spi.SchedulerPlugin;
27
28 /**
29  * Base class for plugins that wish to support having their start and
30  * shutdown methods run within a <code>UserTransaction</code>. This is
31  * often necessary if using the JobStoreCMT and the plugin interacts with
32  * jobs/triggers.
33  *
34  * <p>
35  * The subclass should implement start(UserTransaction) and
36  * shutdown(UserTransaction). The <code>UserTransaction</code> will be
37  * non-null if property <em>wrapInUserTransaction</em> is set to true.
38  * </p>
39  * <p>
40  * For convenience, this base class also provides an initialize() implementation
41  * which saves the scheduler and plugin name, as well as getLog() for logging.
42  * </p>
43  */
44 public abstract class SchedulerPluginWithUserTransactionSupport implements
45     SchedulerPlugin {
46
47     private String JavaDoc name;
48     private Scheduler scheduler;
49     private final Log log = LogFactory.getLog(getClass());
50
51     // Properties
52
53     private boolean wrapInUserTransaction = false;
54
55     /**
56      * <p>
57      * Called when the associated <code>Scheduler</code> is started, in order
58      * to let the plug-in know it can now make calls into the scheduler if it
59      * needs to.
60      * </p>
61      *
62      * <p>
63      * If UserTransaction is not null, the plugin can call setRollbackOnly()
64      * on it to signal that the wrapped transaction should rollback.
65      * </p>
66      *
67      * @param userTransaction The UserTranaction object used to provide a
68      * transaction around the start() operation. It will be null if
69      * <em>wrapInUserTransaction</em> is false or if the transaction failed
70      * to be started.
71      */
72     protected void start(UserTransaction JavaDoc userTransaction) {
73     }
74
75     /**
76      * <p>
77      * Called in order to inform the <code>SchedulerPlugin</code> that it
78      * should free up all of it's resources because the scheduler is shutting
79      * down.
80      * </p>
81      *
82      * <p>
83      * If UserTransaction is not null, the plugin can call setRollbackOnly()
84      * on it to signal that the wrapped transaction should rollback.
85      * </p>
86      *
87      * @param userTransaction The UserTranaction object used to provide a
88      * transaction around the shutdown() operation. It will be null if
89      * <em>wrapInUserTransaction</em> is false or if the transaction failed
90      * to be started.
91      */
92     protected void shutdown(UserTransaction JavaDoc userTransaction) {
93     }
94
95     /**
96      * Get the commons Log for this class.
97      */
98     protected Log getLog() {
99         return log;
100     }
101
102     /**
103      * Get the name of this plugin. Set as part of initialize().
104      */
105     protected String JavaDoc getName() {
106         return name;
107     }
108
109     /**
110      * Get this plugin's <code>Scheduler</code>. Set as part of initialize().
111      */
112     protected Scheduler getScheduler() {
113         return scheduler;
114     }
115
116     public void initialize(String JavaDoc name, Scheduler scheduler) throws SchedulerException {
117         this.name = name;
118         this.scheduler = scheduler;
119     }
120     
121     /**
122      * Wrap the start() and shutdown() methods in a UserTransaction. This is necessary
123      * for some plugins if using the JobStoreCMT.
124      */
125     public boolean getWrapInUserTransaction() {
126         return wrapInUserTransaction;
127     }
128
129     /**
130      * Wrap the start() and shutdown() methods in a UserTransaction. This is necessary
131      * for some plugins if using the JobStoreCMT.
132      */
133     public void setWrapInUserTransaction(boolean wrapInUserTransaction) {
134         this.wrapInUserTransaction = wrapInUserTransaction;
135     }
136
137     /**
138      * Based on the value of <em>wrapInUserTransaction</em>, wraps the
139      * call to start(UserTransaction) in a UserTransaction.
140      */
141     public void start() {
142         UserTransaction JavaDoc userTransaction = startUserTransaction();
143         try {
144             start(userTransaction);
145         } finally {
146             resolveUserTransaction(userTransaction);
147         }
148     }
149
150     /**
151      * Based on the value of <em>wrapInUserTransaction</em>, wraps the
152      * call to shutdown(UserTransaction) in a UserTransaction.
153      */
154     public void shutdown() {
155         UserTransaction JavaDoc userTransaction = startUserTransaction();
156         try {
157             shutdown(userTransaction);
158         } finally {
159             resolveUserTransaction(userTransaction);
160         }
161     }
162         
163     /**
164      * If <em>wrapInUserTransaction</em> is true, starts a new UserTransaction
165      * and returns it. Otherwise, or if establishing the transaction fail, it
166      * will return null.
167      */
168     private UserTransaction JavaDoc startUserTransaction() {
169         if (wrapInUserTransaction == false) {
170             return null;
171         }
172         
173         UserTransaction JavaDoc userTransaction = null;
174         try {
175             userTransaction = UserTransactionHelper.lookupUserTransaction();
176             userTransaction.begin();
177         } catch (Throwable JavaDoc t) {
178             UserTransactionHelper.returnUserTransaction(userTransaction);
179             userTransaction = null;
180             getLog().error("Failed to start UserTransaction for plugin: " + getName(), t);
181         }
182         
183         return userTransaction;
184     }
185     
186     /**
187      * If the given UserTransaction is not null, it is committed/rolledback,
188      * and then returned to the UserTransactionHelper.
189      */
190     private void resolveUserTransaction(UserTransaction JavaDoc userTransaction) {
191         if (userTransaction != null) {
192             try {
193                 if (userTransaction.getStatus() == Status.STATUS_MARKED_ROLLBACK) {
194                     userTransaction.rollback();
195                 } else {
196                     userTransaction.commit();
197                 }
198             } catch (Throwable JavaDoc t) {
199                 getLog().error("Failed to resolve UserTransaction for plugin: " + getName(), t);
200             } finally {
201                 UserTransactionHelper.returnUserTransaction(userTransaction);
202             }
203         }
204     }
205 }
206
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