Source Code Cross Referenced for AtomicLong.java in  » 6.0-JDK-Core » Collections-Jar-Zip-Logging-regex » java » util » concurrent » atomic » Java Source Code / Java DocumentationJava Source Code and Java Documentation

Home
Java Source Code / Java Documentation
1.6.0 JDK Core
2.6.0 JDK Modules
3.6.0 JDK Modules com.sun
4.6.0 JDK Modules com.sun.java
5.6.0 JDK Modules sun
6.6.0 JDK Platform
7.Ajax
8.Apache Harmony Java SE
9.Aspect oriented
10.Authentication Authorization
11.Blogger System
12.Build
13.Byte Code
14.Cache
15.Chart
16.Chat
17.Code Analyzer
18.Collaboration
19.Content Management System
20.Database Client
21.Database DBMS
22.Database JDBC Connection Pool
23.Database ORM
24.Development
25.EJB Server
26.ERP CRM Financial
27.ESB
28.Forum
29.Game
30.GIS
31.Graphic 3D
32.Graphic Library
33.Groupware
34.HTML Parser
35.IDE
36.IDE Eclipse
37.IDE Netbeans
38.Installer
39.Internationalization Localization
40.Inversion of Control
41.Issue Tracking
42.J2EE
43.J2ME
44.JBoss
45.JMS
46.JMX
47.Library
48.Mail Clients
49.Music
50.Net
51.Parser
52.PDF
53.Portal
54.Profiler
55.Project Management
56.Report
57.RSS RDF
58.Rule Engine
59.Science
60.Scripting
61.Search Engine
62.Security
63.Sevlet Container
64.Source Control
65.Swing Library
66.Template Engine
67.Test Coverage
68.Testing
69.UML
70.Web Crawler
71.Web Framework
72.Web Mail
73.Web Server
74.Web Services
75.Web Services apache cxf 2.2.6
76.Web Services AXIS2
77.Wiki Engine
78.Workflow Engines
79.XML
80.XML UI
Java Source Code / Java Documentation » 6.0 JDK Core » Collections Jar Zip Logging regex » java.util.concurrent.atomic 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001        /*
002         * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
003         *
004         * This code is free software; you can redistribute it and/or modify it
005         * under the terms of the GNU General Public License version 2 only, as
006         * published by the Free Software Foundation.  Sun designates this
007         * particular file as subject to the "Classpath" exception as provided
008         * by Sun in the LICENSE file that accompanied this code.
009         *
010         * This code is distributed in the hope that it will be useful, but WITHOUT
011         * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
012         * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
013         * version 2 for more details (a copy is included in the LICENSE file that
014         * accompanied this code).
015         *
016         * You should have received a copy of the GNU General Public License version
017         * 2 along with this work; if not, write to the Free Software Foundation,
018         * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
019         *
020         * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
021         * CA 95054 USA or visit www.sun.com if you need additional information or
022         * have any questions.
023         */
024
025        /*
026         * This file is available under and governed by the GNU General Public
027         * License version 2 only, as published by the Free Software Foundation.
028         * However, the following notice accompanied the original version of this
029         * file:
030         *
031         * Written by Doug Lea with assistance from members of JCP JSR-166
032         * Expert Group and released to the public domain, as explained at
033         * http://creativecommons.org/licenses/publicdomain
034         */
035
036        package java.util.concurrent.atomic;
037
038        import sun.misc.Unsafe;
039
040        /**
041         * A {@code long} value that may be updated atomically.  See the
042         * {@link java.util.concurrent.atomic} package specification for
043         * description of the properties of atomic variables. An
044         * {@code AtomicLong} is used in applications such as atomically
045         * incremented sequence numbers, and cannot be used as a replacement
046         * for a {@link java.lang.Long}. However, this class does extend
047         * {@code Number} to allow uniform access by tools and utilities that
048         * deal with numerically-based classes.
049         *
050         * @since 1.5
051         * @author Doug Lea
052         */
053        public class AtomicLong extends Number implements  java.io.Serializable {
054            private static final long serialVersionUID = 1927816293512124184L;
055
056            // setup to use Unsafe.compareAndSwapLong for updates
057            private static final Unsafe unsafe = Unsafe.getUnsafe();
058            private static final long valueOffset;
059
060            /**
061             * Records whether the underlying JVM supports lockless
062             * compareAndSwap for longs. While the Unsafe.compareAndSwapLong
063             * method works in either case, some constructions should be
064             * handled at Java level to avoid locking user-visible locks.
065             */
066            static final boolean VM_SUPPORTS_LONG_CAS = VMSupportsCS8();
067
068            /**
069             * Returns whether underlying JVM supports lockless CompareAndSet
070             * for longs. Called only once and cached in VM_SUPPORTS_LONG_CAS.
071             */
072            private static native boolean VMSupportsCS8();
073
074            static {
075                try {
076                    valueOffset = unsafe.objectFieldOffset(AtomicLong.class
077                            .getDeclaredField("value"));
078                } catch (Exception ex) {
079                    throw new Error(ex);
080                }
081            }
082
083            private volatile long value;
084
085            /**
086             * Creates a new AtomicLong with the given initial value.
087             *
088             * @param initialValue the initial value
089             */
090            public AtomicLong(long initialValue) {
091                value = initialValue;
092            }
093
094            /**
095             * Creates a new AtomicLong with initial value {@code 0}.
096             */
097            public AtomicLong() {
098            }
099
100            /**
101             * Gets the current value.
102             *
103             * @return the current value
104             */
105            public final long get() {
106                return value;
107            }
108
109            /**
110             * Sets to the given value.
111             *
112             * @param newValue the new value
113             */
114            public final void set(long newValue) {
115                value = newValue;
116            }
117
118            /**
119             * Eventually sets to the given value.
120             *
121             * @param newValue the new value
122             * @since 1.6
123             */
124            public final void lazySet(long newValue) {
125                unsafe.putOrderedLong(this , valueOffset, newValue);
126            }
127
128            /**
129             * Atomically sets to the given value and returns the old value.
130             *
131             * @param newValue the new value
132             * @return the previous value
133             */
134            public final long getAndSet(long newValue) {
135                while (true) {
136                    long current = get();
137                    if (compareAndSet(current, newValue))
138                        return current;
139                }
140            }
141
142            /**
143             * Atomically sets the value to the given updated value
144             * if the current value {@code ==} the expected value.
145             *
146             * @param expect the expected value
147             * @param update the new value
148             * @return true if successful. False return indicates that
149             * the actual value was not equal to the expected value.
150             */
151            public final boolean compareAndSet(long expect, long update) {
152                return unsafe.compareAndSwapLong(this , valueOffset, expect,
153                        update);
154            }
155
156            /**
157             * Atomically sets the value to the given updated value
158             * if the current value {@code ==} the expected value.
159             *
160             * <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
161             * and does not provide ordering guarantees, so is only rarely an
162             * appropriate alternative to {@code compareAndSet}.
163             *
164             * @param expect the expected value
165             * @param update the new value
166             * @return true if successful.
167             */
168            public final boolean weakCompareAndSet(long expect, long update) {
169                return unsafe.compareAndSwapLong(this , valueOffset, expect,
170                        update);
171            }
172
173            /**
174             * Atomically increments by one the current value.
175             *
176             * @return the previous value
177             */
178            public final long getAndIncrement() {
179                while (true) {
180                    long current = get();
181                    long next = current + 1;
182                    if (compareAndSet(current, next))
183                        return current;
184                }
185            }
186
187            /**
188             * Atomically decrements by one the current value.
189             *
190             * @return the previous value
191             */
192            public final long getAndDecrement() {
193                while (true) {
194                    long current = get();
195                    long next = current - 1;
196                    if (compareAndSet(current, next))
197                        return current;
198                }
199            }
200
201            /**
202             * Atomically adds the given value to the current value.
203             *
204             * @param delta the value to add
205             * @return the previous value
206             */
207            public final long getAndAdd(long delta) {
208                while (true) {
209                    long current = get();
210                    long next = current + delta;
211                    if (compareAndSet(current, next))
212                        return current;
213                }
214            }
215
216            /**
217             * Atomically increments by one the current value.
218             *
219             * @return the updated value
220             */
221            public final long incrementAndGet() {
222                for (;;) {
223                    long current = get();
224                    long next = current + 1;
225                    if (compareAndSet(current, next))
226                        return next;
227                }
228            }
229
230            /**
231             * Atomically decrements by one the current value.
232             *
233             * @return the updated value
234             */
235            public final long decrementAndGet() {
236                for (;;) {
237                    long current = get();
238                    long next = current - 1;
239                    if (compareAndSet(current, next))
240                        return next;
241                }
242            }
243
244            /**
245             * Atomically adds the given value to the current value.
246             *
247             * @param delta the value to add
248             * @return the updated value
249             */
250            public final long addAndGet(long delta) {
251                for (;;) {
252                    long current = get();
253                    long next = current + delta;
254                    if (compareAndSet(current, next))
255                        return next;
256                }
257            }
258
259            /**
260             * Returns the String representation of the current value.
261             * @return the String representation of the current value.
262             */
263            public String toString() {
264                return Long.toString(get());
265            }
266
267            public int intValue() {
268                return (int) get();
269            }
270
271            public long longValue() {
272                return (long) get();
273            }
274
275            public float floatValue() {
276                return (float) get();
277            }
278
279            public double doubleValue() {
280                return (double) get();
281            }
282
283        }
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.