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1 /* ====================================================================
2 * License:
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
14 * distribution.
15 *
16 * 3. The end-user documentation included with the redistribution,
17 * if any, must include the following acknowledgment:
18 * "This product includes software developed by
19 * Robert Half International (http://www.rhi.com/)."
20 * Alternately, this acknowledgment may appear in the software itself,
21 * if and wherever such third-party acknowledgments normally appear.
22 *
23 * 4. The names "Parc", "RHI", and "Robert Half International" must
24 * not be used to endorse or promote products derived from this
25 * software without prior written permission. For written
26 * permission, please contact pete.mckinstry@rhi.com.
27 *
28 * 5. Products derived from this software may not be called "PARC",
29 * nor may "PARC" appear in their name, without prior written
30 * permission of Robert Half International.
31 *
32 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
33 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
34 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
35 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
36 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
37 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
38 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
39 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
40 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
41 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
42 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 * SUCH DAMAGE.
44 * ====================================================================
45 *
46 */
47 package com.rhi.architecture.parc;
48
49 import com.rhi.architecture.parc.channel.AbstractChannel;
50
51 import java.util.Collection;
52 import java.util.LinkedList;
53
54 /***
55 * LinkedListQueue - general purpose implementation of Channel.
56 *
57 * @author Pete McKinstry
58 * @copyright 2002, Robert Half Int'l., Inc. All rights reserved.
59 *
60 * @since 1.0
61 */
62 public class LinkedListQueue extends AbstractChannel {
63
64 // implementation all deferred to this class.
65 //private LinkedQueue queueHelper;
66 private LinkedList queueHelper;
67 private Object lock;
68
69 /***
70 * Default constructor.
71 *
72 * @since 1.0
73 */
74 public LinkedListQueue() {
75 //queueHelper = Collections.synchronizedList(new LinkedList());
76 queueHelper = new LinkedList();
77 lock = new Object();
78 }
79
80 /***
81 * Push an entire collection into the channel. Useful for batch
82 * of an entire set of records.
83 *
84 * @param collection of records to enqueue.
85 *
86 * @exception ProcessingException
87 *
88 * @since 1.0
89 */
90 public void push(Collection collection) throws ProcessingException {
91 synchronized (lock) {
92 // blocks waiting for queue availability.
93 queueHelper.addAll(collection);
94 }
95
96 notifyMonitors();
97 }
98
99 /***
100 * Pull a set of records out of the channel for processing.
101 *
102 * @param max - the max number of records to pull from the channel.
103 * @return Collection of records returned from channel.
104 *
105 * @throws ProcessingException
106 *
107 * @since 1.0
108 */
109 public Collection pull(int max) throws ProcessingException {
110 LinkedList list = new LinkedList();
111
112 synchronized (lock) {
113 int size = queueHelper.size();
114 for (int i = 0;(i < max) && (size > 0); ++i) {
115 // faster to pull from the end of the array instead
116 // of the beginning, and order shouldn't matter.
117 Object o = queueHelper.remove(--size);
118 list.add(o);
119 }
120 }
121 return list;
122 }
123
124 /***
125 * Simple <code>Object</code> based clone() method. The reason this is
126 * okay is because i'm counting on re-using the same channel between
127 * each filter. That's where the concurrency comes in & why i'm using
128 * Doug Lea's package in the first place. In this case, simple is good.
129 *
130 * @return Queue object
131 *
132 * @since 1.0
133 */
134 public Object clone() {
135 LinkedListQueue q = (LinkedListQueue) super.clone();
136 q.queueHelper = new LinkedList();
137 q.lock = new Object();
138 return q;
139 }
140
141 }
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