1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/rt/emul/compact/src/main/java/java/util/concurrent/atomic/AtomicLong.java Thu Oct 03 15:40:35 2013 +0200
1.3 @@ -0,0 +1,279 @@
1.4 +/*
1.5 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.6 + *
1.7 + * This code is free software; you can redistribute it and/or modify it
1.8 + * under the terms of the GNU General Public License version 2 only, as
1.9 + * published by the Free Software Foundation. Oracle designates this
1.10 + * particular file as subject to the "Classpath" exception as provided
1.11 + * by Oracle in the LICENSE file that accompanied this code.
1.12 + *
1.13 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.14 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.15 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.16 + * version 2 for more details (a copy is included in the LICENSE file that
1.17 + * accompanied this code).
1.18 + *
1.19 + * You should have received a copy of the GNU General Public License version
1.20 + * 2 along with this work; if not, write to the Free Software Foundation,
1.21 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.22 + *
1.23 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.24 + * or visit www.oracle.com if you need additional information or have any
1.25 + * questions.
1.26 + */
1.27 +
1.28 +/*
1.29 + * This file is available under and governed by the GNU General Public
1.30 + * License version 2 only, as published by the Free Software Foundation.
1.31 + * However, the following notice accompanied the original version of this
1.32 + * file:
1.33 + *
1.34 + * Written by Doug Lea with assistance from members of JCP JSR-166
1.35 + * Expert Group and released to the public domain, as explained at
1.36 + * http://creativecommons.org/publicdomain/zero/1.0/
1.37 + */
1.38 +
1.39 +package java.util.concurrent.atomic;
1.40 +import sun.misc.Unsafe;
1.41 +
1.42 +/**
1.43 + * A {@code long} value that may be updated atomically. See the
1.44 + * {@link java.util.concurrent.atomic} package specification for
1.45 + * description of the properties of atomic variables. An
1.46 + * {@code AtomicLong} is used in applications such as atomically
1.47 + * incremented sequence numbers, and cannot be used as a replacement
1.48 + * for a {@link java.lang.Long}. However, this class does extend
1.49 + * {@code Number} to allow uniform access by tools and utilities that
1.50 + * deal with numerically-based classes.
1.51 + *
1.52 + * @since 1.5
1.53 + * @author Doug Lea
1.54 + */
1.55 +public class AtomicLong extends Number implements java.io.Serializable {
1.56 + private static final long serialVersionUID = 1927816293512124184L;
1.57 +
1.58 + // setup to use Unsafe.compareAndSwapLong for updates
1.59 + private static final Unsafe unsafe = Unsafe.getUnsafe();
1.60 + private static final long valueOffset;
1.61 +
1.62 + /**
1.63 + * Records whether the underlying JVM supports lockless
1.64 + * compareAndSwap for longs. While the Unsafe.compareAndSwapLong
1.65 + * method works in either case, some constructions should be
1.66 + * handled at Java level to avoid locking user-visible locks.
1.67 + */
1.68 + static final boolean VM_SUPPORTS_LONG_CAS = VMSupportsCS8();
1.69 +
1.70 + /**
1.71 + * Returns whether underlying JVM supports lockless CompareAndSet
1.72 + * for longs. Called only once and cached in VM_SUPPORTS_LONG_CAS.
1.73 + */
1.74 + private static native boolean VMSupportsCS8();
1.75 +
1.76 + static {
1.77 + try {
1.78 + valueOffset = unsafe.objectFieldOffset
1.79 + (AtomicLong.class.getDeclaredField("value"));
1.80 + } catch (Exception ex) { throw new Error(ex); }
1.81 + }
1.82 +
1.83 + private volatile long value;
1.84 +
1.85 + /**
1.86 + * Creates a new AtomicLong with the given initial value.
1.87 + *
1.88 + * @param initialValue the initial value
1.89 + */
1.90 + public AtomicLong(long initialValue) {
1.91 + value = initialValue;
1.92 + }
1.93 +
1.94 + /**
1.95 + * Creates a new AtomicLong with initial value {@code 0}.
1.96 + */
1.97 + public AtomicLong() {
1.98 + }
1.99 +
1.100 + /**
1.101 + * Gets the current value.
1.102 + *
1.103 + * @return the current value
1.104 + */
1.105 + public final long get() {
1.106 + return value;
1.107 + }
1.108 +
1.109 + /**
1.110 + * Sets to the given value.
1.111 + *
1.112 + * @param newValue the new value
1.113 + */
1.114 + public final void set(long newValue) {
1.115 + value = newValue;
1.116 + }
1.117 +
1.118 + /**
1.119 + * Eventually sets to the given value.
1.120 + *
1.121 + * @param newValue the new value
1.122 + * @since 1.6
1.123 + */
1.124 + public final void lazySet(long newValue) {
1.125 + unsafe.putOrderedLong(this, valueOffset, newValue);
1.126 + }
1.127 +
1.128 + /**
1.129 + * Atomically sets to the given value and returns the old value.
1.130 + *
1.131 + * @param newValue the new value
1.132 + * @return the previous value
1.133 + */
1.134 + public final long getAndSet(long newValue) {
1.135 + while (true) {
1.136 + long current = get();
1.137 + if (compareAndSet(current, newValue))
1.138 + return current;
1.139 + }
1.140 + }
1.141 +
1.142 + /**
1.143 + * Atomically sets the value to the given updated value
1.144 + * if the current value {@code ==} the expected value.
1.145 + *
1.146 + * @param expect the expected value
1.147 + * @param update the new value
1.148 + * @return true if successful. False return indicates that
1.149 + * the actual value was not equal to the expected value.
1.150 + */
1.151 + public final boolean compareAndSet(long expect, long update) {
1.152 + return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
1.153 + }
1.154 +
1.155 + /**
1.156 + * Atomically sets the value to the given updated value
1.157 + * if the current value {@code ==} the expected value.
1.158 + *
1.159 + * <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
1.160 + * and does not provide ordering guarantees, so is only rarely an
1.161 + * appropriate alternative to {@code compareAndSet}.
1.162 + *
1.163 + * @param expect the expected value
1.164 + * @param update the new value
1.165 + * @return true if successful.
1.166 + */
1.167 + public final boolean weakCompareAndSet(long expect, long update) {
1.168 + return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
1.169 + }
1.170 +
1.171 + /**
1.172 + * Atomically increments by one the current value.
1.173 + *
1.174 + * @return the previous value
1.175 + */
1.176 + public final long getAndIncrement() {
1.177 + while (true) {
1.178 + long current = get();
1.179 + long next = current + 1;
1.180 + if (compareAndSet(current, next))
1.181 + return current;
1.182 + }
1.183 + }
1.184 +
1.185 + /**
1.186 + * Atomically decrements by one the current value.
1.187 + *
1.188 + * @return the previous value
1.189 + */
1.190 + public final long getAndDecrement() {
1.191 + while (true) {
1.192 + long current = get();
1.193 + long next = current - 1;
1.194 + if (compareAndSet(current, next))
1.195 + return current;
1.196 + }
1.197 + }
1.198 +
1.199 + /**
1.200 + * Atomically adds the given value to the current value.
1.201 + *
1.202 + * @param delta the value to add
1.203 + * @return the previous value
1.204 + */
1.205 + public final long getAndAdd(long delta) {
1.206 + while (true) {
1.207 + long current = get();
1.208 + long next = current + delta;
1.209 + if (compareAndSet(current, next))
1.210 + return current;
1.211 + }
1.212 + }
1.213 +
1.214 + /**
1.215 + * Atomically increments by one the current value.
1.216 + *
1.217 + * @return the updated value
1.218 + */
1.219 + public final long incrementAndGet() {
1.220 + for (;;) {
1.221 + long current = get();
1.222 + long next = current + 1;
1.223 + if (compareAndSet(current, next))
1.224 + return next;
1.225 + }
1.226 + }
1.227 +
1.228 + /**
1.229 + * Atomically decrements by one the current value.
1.230 + *
1.231 + * @return the updated value
1.232 + */
1.233 + public final long decrementAndGet() {
1.234 + for (;;) {
1.235 + long current = get();
1.236 + long next = current - 1;
1.237 + if (compareAndSet(current, next))
1.238 + return next;
1.239 + }
1.240 + }
1.241 +
1.242 + /**
1.243 + * Atomically adds the given value to the current value.
1.244 + *
1.245 + * @param delta the value to add
1.246 + * @return the updated value
1.247 + */
1.248 + public final long addAndGet(long delta) {
1.249 + for (;;) {
1.250 + long current = get();
1.251 + long next = current + delta;
1.252 + if (compareAndSet(current, next))
1.253 + return next;
1.254 + }
1.255 + }
1.256 +
1.257 + /**
1.258 + * Returns the String representation of the current value.
1.259 + * @return the String representation of the current value.
1.260 + */
1.261 + public String toString() {
1.262 + return Long.toString(get());
1.263 + }
1.264 +
1.265 +
1.266 + public int intValue() {
1.267 + return (int)get();
1.268 + }
1.269 +
1.270 + public long longValue() {
1.271 + return get();
1.272 + }
1.273 +
1.274 + public float floatValue() {
1.275 + return (float)get();
1.276 + }
1.277 +
1.278 + public double doubleValue() {
1.279 + return (double)get();
1.280 + }
1.281 +
1.282 +}