01: /*
02: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
03: *
04: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
05: *
06: * The contents of this file are subject to the terms of either the GNU
07: * General Public License Version 2 only ("GPL") or the Common Development
08: * and Distribution License("CDDL") (collectively, the "License"). You
09: * may not use this file except in compliance with the License. You can obtain
10: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
11: * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
12: * language governing permissions and limitations under the License.
13: *
14: * When distributing the software, include this License Header Notice in each
15: * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
16: * Sun designates this particular file as subject to the "Classpath" exception
17: * as provided by Sun in the GPL Version 2 section of the License file that
18: * accompanied this code. If applicable, add the following below the License
19: * Header, with the fields enclosed by brackets [] replaced by your own
20: * identifying information: "Portions Copyrighted [year]
21: * [name of copyright owner]"
22: *
23: * Contributor(s):
24: *
25: * If you wish your version of this file to be governed by only the CDDL or
26: * only the GPL Version 2, indicate your decision by adding "[Contributor]
27: * elects to include this software in this distribution under the [CDDL or GPL
28: * Version 2] license." If you don't indicate a single choice of license, a
29: * recipient has the option to distribute your version of this file under
30: * either the CDDL, the GPL Version 2 or to extend the choice of license to
31: * its licensees as provided above. However, if you add GPL Version 2 code
32: * and therefore, elected the GPL Version 2 license, then the option applies
33: * only if the new code is made subject to such option by the copyright
34: * holder.
35: */
36:
37: package com.sun.xml.ws.transport.tcp.connectioncache.spi.concurrent;
38:
39: /** A class that provides a very simply unbounded queue.
40: * The main requirement here is that the class support constant time (very fast)
41: * deletion of arbitrary elements. An instance of this class must be thread safe,
42: * either by locking or by using a wait-free algorithm (preferred).
43: * The interface is made as simple is possible to make it easier to produce
44: * a wait-free implementation.
45: */
46: public interface ConcurrentQueue<V> {
47: /** A Handle provides the capability to delete an element of a ConcurrentQueue
48: * very quickly. Typically, the handle is stored in the element, so that an
49: * element located from another data structure can be quickly deleted from
50: * a ConcurrentQueue.
51: */
52: public interface Handle<V> {
53: /** Return the value that corresponds to this handle.
54: */
55: V value();
56:
57: /** Delete the element corresponding to this handle
58: * from the queue. Takes constant time. Returns
59: * true if the removal succeeded, or false if it failed.
60: * which can occur if another thread has already called
61: * poll or remove on this element.
62: */
63: boolean remove();
64: }
65:
66: /** Return the number of elements in the queue.
67: */
68: int size();
69:
70: /** Add a new element to the tail of the queue.
71: * Returns a handle for the element in the queue.
72: */
73: Handle<V> offer(V arg);
74:
75: /** Return an element from the head of the queue.
76: * The element is removed from the queue.
77: */
78: V poll();
79: }
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