1 /**
2 * Copyright 2003-2007 Greg Luck
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy 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,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package net.sf.ehcache.constructs.asynchronous;
18
19 import org.apache.commons.logging.Log;
20 import org.apache.commons.logging.LogFactory;
21
22 import java.io.ByteArrayOutputStream;
23 import java.io.IOException;
24 import java.io.ObjectOutputStream;
25 import java.io.Serializable;
26
27
28 /**
29 * A test command
30 * @author <a href="mailto:gluck@thoughtworks.com">Greg Luck</a>
31 * @version $Id: ListAppenderCommand.java 512 2007-07-10 09:18:45Z gregluck $
32 */
33 class ListAppenderCommand implements Command {
34
35 private static final Log LOG = LogFactory.getLog(ListAppenderCommand.class.getName());
36
37 private static final int NUMBER_OF_ATTEMPTS = 3;
38 private static final int DELAY_IN_SECONDS = 1200;
39 private Serializable payload;
40 private long timeToCompleteInMs;
41 private Class exceptionOnExecute;
42
43 /**
44 * Constructor
45 */
46 public ListAppenderCommand(Serializable payload, long timeToCompleteInMs, Class exceptionOnExecute) {
47 this.payload = payload;
48 this.timeToCompleteInMs = timeToCompleteInMs;
49 this.exceptionOnExecute = exceptionOnExecute;
50
51 }
52
53
54 /**
55 * Executes the command. The command is successful if it does not throw an exception.
56 *
57 * @throws Throwable A command could do anything and could throw any {@link Exception} or {@link Error}
58 * @see #getThrowablesToRetryOn() to set {@link Throwable}s that should are expected
59 */
60 public void execute() throws Throwable {
61 LOG.debug("About to attempt execution");
62 checkSerializability(payload);
63 Thread.sleep(timeToCompleteInMs);
64 if (exceptionOnExecute != null) {
65 throw (Throwable) exceptionOnExecute.newInstance();
66 }
67 AsynchronousCommandExecutorTest.getMessages().add(payload);
68 }
69
70 private void checkSerializability(Serializable payload) throws IOException {
71 ObjectOutputStream oout = new ObjectOutputStream(new ByteArrayOutputStream());
72 oout.writeObject(payload);
73 }
74
75 /**
76 * The AsynchronousCommandExecutor may also be fault tolerant. This method returns a list of {@link Throwable}
77 * classes such that if one if thrown during an execute attempt the command will simply retry after an interval
78 * until it uses up all of its retry attempts. If a {@link Throwable} does occurs which is not in this list,
79 * an {@link AsynchronousCommandException} will be thrown and the command will be removed.
80 * <p/>
81 *
82 * @return a list of {@link Class}s. It only makes sense for the list to contain Classes which are subclasses
83 * of Throwable
84 */
85 public Class[] getThrowablesToRetryOn() {
86 return new Class[]{Exception.class};
87 }
88
89 /**
90 * @return the number of times the dispatcher should try to send the message. A non-zero value implies fault tolerance
91 * and only makes sense if {@link #getThrowablesToRetryOn()} is non-null.
92 */
93 public int getNumberOfAttempts() {
94 return NUMBER_OF_ATTEMPTS;
95 }
96
97 /**
98 * @return the delay between attempts, in seconds. A non-zero value implies fault tolerance
99 * and only makes sense if {@link #getThrowablesToRetryOn()} is non-null.
100 */
101 public int getDelayBetweenAttemptsInSeconds() {
102 return DELAY_IN_SECONDS;
103 }
104 }
105