1 package org.apache.turbine.services.schedule;
2
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 import java.util.Collections;
23 import java.util.Comparator;
24 import java.util.List;
25 import java.util.Vector;
26
27 import org.apache.turbine.util.TurbineException;
28
29 /**
30 * Queue for the scheduler.
31 *
32 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
33 * @author <a href="mailto:quintonm@bellsouth.net">Quinton McCombs</a>
34 * @version $Id: JobQueue.java 615328 2008-01-25 20:25:05Z tv $
35 */
36 public class JobQueue
37 {
38 /**
39 * The queue of <code>JobEntry</code> objects.
40 */
41 private Vector<JobEntry> queue = null;
42
43 /**
44 * Creates a new instance.
45 */
46 public JobQueue()
47 {
48 queue = new Vector<JobEntry>(10);
49 }
50
51 /**
52 * Return the next job off the top of the queue, or <code>null</code> if
53 * there are no jobs in the queue.
54 *
55 * @return The next job in the queue.
56 */
57 public JobEntry getNext()
58 {
59 if (queue.size() > 0)
60 {
61 return queue.elementAt(0);
62 }
63 else
64 {
65 return null;
66 }
67 }
68
69 /**
70 * Return a specific job.
71 *
72 * @param je The JobEntry we are looking for.
73 * @return A JobEntry.
74 */
75 public JobEntry getJob(JobEntry je)
76 {
77 int index = -1;
78
79 if (je != null)
80 {
81 index = queue.indexOf(je);
82 }
83
84 if (index < 0)
85 {
86 return null;
87 }
88 else
89 {
90 return queue.elementAt(index);
91 }
92 }
93
94 /**
95 * List jobs in the queue. This is used by the scheduler UI.
96 *
97 * @return A Vector of <code>JobEntry</code> objects.
98 */
99 @SuppressWarnings("unchecked")
100 public Vector<JobEntry> list()
101 {
102 if (queue != null && queue.size() > 0)
103 {
104 return (Vector<JobEntry>) queue.clone();
105 }
106 else
107 {
108 return null;
109 }
110 }
111
112 /**
113 * Add a job to the queue.
114 *
115 * @param je A JobEntry job.
116 */
117 public synchronized void add(JobEntry je)
118 {
119 queue.addElement(je);
120 sortQueue();
121 }
122
123 /**
124 * Batch load jobs. Retains any already enqueued jobs. Called on
125 * <code>SchedulerService</code> start-up.
126 *
127 * @param jobEntries A list of the <code>JobEntry</code> objects to load.
128 */
129 public synchronized void batchLoad(List<JobEntry> jobEntries)
130 {
131 if (jobEntries != null)
132 {
133 queue.addAll(jobEntries);
134 sortQueue();
135 }
136
137 }
138
139 /**
140 * Remove a job from the queue.
141 *
142 * @param je A JobEntry with the job to remove.
143 */
144 public synchronized void remove(JobEntry je)
145 {
146 queue.removeElement(je);
147 sortQueue();
148 }
149
150 /**
151 * Modify a job on the queue.
152 *
153 * @param je A JobEntry with the job to modify
154 */
155 public synchronized void modify(JobEntry je)
156 throws TurbineException
157 {
158 remove(je);
159 je.calcRunTime();
160 this.add(je);
161 sortQueue();
162 }
163
164 /**
165 * Update the job for its next run time.
166 *
167 * @param je A JobEntry to be updated.
168 * @exception TurbineException a generic exception.
169 */
170 public synchronized void updateQueue(JobEntry je)
171 throws TurbineException
172 {
173 je.calcRunTime();
174 sortQueue();
175 }
176
177 /**
178 * Re-sort the existing queue. Consumers of this method should be
179 * <code>synchronized</code>.
180 */
181 private void sortQueue()
182 {
183 Comparator<JobEntry> aComparator = new Comparator<JobEntry>()
184 {
185 public int compare(JobEntry o1, JobEntry o2)
186 {
187 Long time1 = new Long(o1.getNextRuntime());
188 Long time2 = new Long(o2.getNextRuntime());
189 return (time1.compareTo(time2));
190 }
191 };
192
193 Collections.sort(queue, aComparator);
194 }
195 }