001 package org.apache.turbine.services.schedule;
002
003 /*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements. See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership. The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License. You may obtain a copy of the License at
011 *
012 * http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied. See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022 import java.util.Collections;
023 import java.util.Comparator;
024 import java.util.List;
025 import java.util.Vector;
026
027 import org.apache.turbine.util.TurbineException;
028
029 /**
030 * Queue for the scheduler.
031 *
032 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
033 * @author <a href="mailto:quintonm@bellsouth.net">Quinton McCombs</a>
034 * @version $Id: JobQueue.java 615328 2008-01-25 20:25:05Z tv $
035 */
036 public class JobQueue
037 {
038 /**
039 * The queue of <code>JobEntry</code> objects.
040 */
041 private Vector<JobEntry> queue = null;
042
043 /**
044 * Creates a new instance.
045 */
046 public JobQueue()
047 {
048 queue = new Vector<JobEntry>(10);
049 }
050
051 /**
052 * Return the next job off the top of the queue, or <code>null</code> if
053 * there are no jobs in the queue.
054 *
055 * @return The next job in the queue.
056 */
057 public JobEntry getNext()
058 {
059 if (queue.size() > 0)
060 {
061 return queue.elementAt(0);
062 }
063 else
064 {
065 return null;
066 }
067 }
068
069 /**
070 * Return a specific job.
071 *
072 * @param je The JobEntry we are looking for.
073 * @return A JobEntry.
074 */
075 public JobEntry getJob(JobEntry je)
076 {
077 int index = -1;
078
079 if (je != null)
080 {
081 index = queue.indexOf(je);
082 }
083
084 if (index < 0)
085 {
086 return null;
087 }
088 else
089 {
090 return queue.elementAt(index);
091 }
092 }
093
094 /**
095 * List jobs in the queue. This is used by the scheduler UI.
096 *
097 * @return A Vector of <code>JobEntry</code> objects.
098 */
099 @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 }