##### Coverage Report - com.sun.grizzly.connectioncache.impl.concurrent.ConcurrentQueueImpl

Classes in this File | Line Coverage | Branch Coverage | Complexity
ConcurrentQueueImpl |
96 % | 25/26
75 % | 3/4
| 0.0;0
ConcurrentQueueImpl$Entry |
100 % | 7/7
N/A | N/A
| 0.0;0
ConcurrentQueueImpl$HandleImpl |
89 % | 17/19
50 % | 1/2
| 0.0;0

1 |  |
     /*
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      *
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      * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
4 |  |
      *
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      * Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved.
6 |  |
      *
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      * The contents of this file are subject to the terms of either the GNU
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      * General Public License Version 2 only ("GPL") or the Common Development
9 |  |
      * and Distribution License("CDDL") (collectively, the "License").  You
10 |  |
      * may not use this file except in compliance with the License. You can obtain
11 |  |
      * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
12 |  |
      * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
13 |  |
      * language governing permissions and limitations under the License.
14 |  |
      *
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      * When distributing the software, include this License Header Notice in each
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      * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
17 |  |
      * Sun designates this particular file as subject to the "Classpath" exception
18 |  |
      * as provided by Sun in the GPL Version 2 section of the License file that
19 |  |
      * accompanied this code.  If applicable, add the following below the License
20 |  |
      * Header, with the fields enclosed by brackets [] replaced by your own
21 |  |
      * identifying information: "Portions Copyrighted [year]
22 |  |
      * [name of copyright owner]"
23 |  |
      *
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      * Contributor(s):
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      *
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      * If you wish your version of this file to be governed by only the CDDL or
27 |  |
      * only the GPL Version 2, indicate your decision by adding "[Contributor]
28 |  |
      * elects to include this software in this distribution under the [CDDL or GPL
29 |  |
      * Version 2] license."  If you don't indicate a single choice of license, a
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      * recipient has the option to distribute your version of this file under
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      * either the CDDL, the GPL Version 2 or to extend the choice of license to
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      * its licensees as provided above.  However, if you add GPL Version 2 code
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      * and therefore, elected the GPL Version 2 license, then the option applies
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      * only if the new code is made subject to such option by the copyright
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      * holder.
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      *
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      */
38 |  |
39 |  |
     package com.sun.grizzly.connectioncache.impl.concurrent;
40 |  |
41 |  |
     import com.sun.grizzly.connectioncache.spi.concurrent.ConcurrentQueue;
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     public class ConcurrentQueueImpl<V> implements ConcurrentQueue<V> {
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         // This implementation of ConcurrentQueue is unsynchronized, for use in
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         // other implementations that manage concurrency with locks.
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         //
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         // Structure: Head points to a node containing a null value, which is a special marker.
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         // head.next is the first element, head.prev is the last.  The queue is empty if
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         // head.next == head.prev == head.
50 | 6 |
         final Entry<V> head = new Entry<V>( null ) ;
51 | 6 |
         int count = 0 ;
52 |  |
53 | 6 |
         public ConcurrentQueueImpl() {
54 | 6 |
             head.next = head ;
55 | 6 |
             head.prev = head ;
56 | 6 |
         }
57 |  |
58 | 1042 |
         private final class Entry<V> {
59 | 1049 |
             Entry<V> next = null ;
60 | 1049 |
             Entry<V> prev = null ;
61 |  |
             private HandleImpl<V> handle ;
62 |  |
63 | 1049 |
             Entry( V value ) {
64 | 1049 |
                 handle = new HandleImpl<V>( this, value ) ;
65 | 1049 |
             }
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67 |  |
             HandleImpl<V> handle() {
68 | 1073 |
                 return handle ;
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             }
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         }
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         private final class HandleImpl<V> implements Handle<V> {
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             private Entry<V> entry ;
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             private final V value ;
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             private boolean valid ;
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77 | 1049 |
             HandleImpl( Entry<V> entry, V value ) {
78 | 1049 |
                 this.entry = entry ;
79 | 1049 |
                 this.value = value ;
80 | 1049 |
                 this.valid = true ;
81 | 1049 |
             }
82 |  |
83 |  |
             Entry<V> entry() {
84 | 0 |
                 return entry ;
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             }
86 |  |
87 |  |
             public V value() {
88 | 15 |
                 return value ;
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             }
90 |  |
91 |  |
             /** Delete the element corresponding to this handle
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              * from the queue.  Takes constant time.
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              * @return  element deleted from queue, (yes or no)
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       */
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             public boolean remove() {
96 | 1042 |
                 if (!valid) {
97 | 0 |
                     return false ;
98 |  |
                 }
99 |  |
100 | 1042 |
                 valid = false ;
101 |  |
102 | 1042 |
                 entry.next.prev = entry.prev ;
103 | 1042 |
                 entry.prev.next = entry.next ;
104 | 1042 |
                 count-- ;
105 |  |
106 | 1042 |
                 entry.prev = null ;
107 | 1042 |
                 entry.next = null ;
108 | 1042 |
                 entry.handle = null ;
109 | 1042 |
                 entry = null ;
110 | 1042 |
                 valid = false ;
111 | 1042 |
                 return true ;
112 |  |
             }
113 |  |
         }
114 |  |
115 |  |
         public int size() {
116 | 64 |
             return count ;
117 |  |
         }
118 |  |
119 |  |
         /** Add a new element to the tail of the queue.
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          * Returns a handle for the element in the queue.
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          * @param arg  element to append to the queue
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          * @return  {@link Handle} for the element in the queue
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          */
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         public Handle<V> offer( V arg ) {
125 | 1043 |
             if (arg == null)
126 | 0 |
                 throw new IllegalArgumentException( "Argument cannot be null" ) ;
127 |  |
128 | 1043 |
             Entry<V> entry = new Entry<V>( arg ) ;
129 |  |
130 | 1043 |
             entry.next = head ;
131 | 1043 |
             entry.prev = head.prev ;
132 | 1043 |
             head.prev.next = entry ;
133 | 1043 |
             head.prev = entry ;
134 | 1043 |
             count++ ;
135 |  |
136 | 1043 |
             return entry.handle() ;
137 |  |
         }
138 |  |
139 |  |
         /** Return an element from the head of the queue.
140 |  |
          * The element is removed from the queue.
141 |  |
          * @return  an element at the head of the queue
142 |  |
          */
143 |  |
         public V poll() {
144 | 23 |
             Entry<V> first = null ;
145 | 23 |
             V value = null ;
146 |  |
147 | 23 |
             first = head.next ;
148 | 23 |
             if (first == head)
149 | 8 |
                 return null ;
150 |  |
             else {
151 | 15 |
                 value = first.handle().value() ;
152 |  |
153 |  |
                 // assert that the following expression returns true!
154 | 15 |
                 first.handle().remove() ;
155 |  |
             }
156 |  |
157 |  |
             // Once first is removed from the queue, it is invisible to other threads,
158 |  |
             // so we don't need to synchronize here.
159 | 15 |
             first.next = null ;
160 | 15 |
             first.prev = null ;
161 | 15 |
             return value ;
162 |  |
         }
163 |  |
     }