--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/concurrent/atomic/AtomicLong.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,279 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+package java.util.concurrent.atomic;
+import sun.misc.Unsafe;
+
+/**
+ * A {@code long} value that may be updated atomically. See the
+ * {@link java.util.concurrent.atomic} package specification for
+ * description of the properties of atomic variables. An
+ * {@code AtomicLong} is used in applications such as atomically
+ * incremented sequence numbers, and cannot be used as a replacement
+ * for a {@link java.lang.Long}. However, this class does extend
+ * {@code Number} to allow uniform access by tools and utilities that
+ * deal with numerically-based classes.
+ *
+ * @since 1.5
+ * @author Doug Lea
+ */
+public class AtomicLong extends Number implements java.io.Serializable {
+ private static final long serialVersionUID = 1927816293512124184L;
+
+ // setup to use Unsafe.compareAndSwapLong for updates
+ private static final Unsafe unsafe = Unsafe.getUnsafe();
+ private static final long valueOffset;
+
+ /**
+ * Records whether the underlying JVM supports lockless
+ * compareAndSwap for longs. While the Unsafe.compareAndSwapLong
+ * method works in either case, some constructions should be
+ * handled at Java level to avoid locking user-visible locks.
+ */
+ static final boolean VM_SUPPORTS_LONG_CAS = VMSupportsCS8();
+
+ /**
+ * Returns whether underlying JVM supports lockless CompareAndSet
+ * for longs. Called only once and cached in VM_SUPPORTS_LONG_CAS.
+ */
+ private static native boolean VMSupportsCS8();
+
+ static {
+ try {
+ valueOffset = unsafe.objectFieldOffset
+ (AtomicLong.class.getDeclaredField("value"));
+ } catch (Exception ex) { throw new Error(ex); }
+ }
+
+ private volatile long value;
+
+ /**
+ * Creates a new AtomicLong with the given initial value.
+ *
+ * @param initialValue the initial value
+ */
+ public AtomicLong(long initialValue) {
+ value = initialValue;
+ }
+
+ /**
+ * Creates a new AtomicLong with initial value {@code 0}.
+ */
+ public AtomicLong() {
+ }
+
+ /**
+ * Gets the current value.
+ *
+ * @return the current value
+ */
+ public final long get() {
+ return value;
+ }
+
+ /**
+ * Sets to the given value.
+ *
+ * @param newValue the new value
+ */
+ public final void set(long newValue) {
+ value = newValue;
+ }
+
+ /**
+ * Eventually sets to the given value.
+ *
+ * @param newValue the new value
+ * @since 1.6
+ */
+ public final void lazySet(long newValue) {
+ unsafe.putOrderedLong(this, valueOffset, newValue);
+ }
+
+ /**
+ * Atomically sets to the given value and returns the old value.
+ *
+ * @param newValue the new value
+ * @return the previous value
+ */
+ public final long getAndSet(long newValue) {
+ while (true) {
+ long current = get();
+ if (compareAndSet(current, newValue))
+ return current;
+ }
+ }
+
+ /**
+ * Atomically sets the value to the given updated value
+ * if the current value {@code ==} the expected value.
+ *
+ * @param expect the expected value
+ * @param update the new value
+ * @return true if successful. False return indicates that
+ * the actual value was not equal to the expected value.
+ */
+ public final boolean compareAndSet(long expect, long update) {
+ return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
+ }
+
+ /**
+ * Atomically sets the value to the given updated value
+ * if the current value {@code ==} the expected value.
+ *
+ * <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
+ * and does not provide ordering guarantees, so is only rarely an
+ * appropriate alternative to {@code compareAndSet}.
+ *
+ * @param expect the expected value
+ * @param update the new value
+ * @return true if successful.
+ */
+ public final boolean weakCompareAndSet(long expect, long update) {
+ return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
+ }
+
+ /**
+ * Atomically increments by one the current value.
+ *
+ * @return the previous value
+ */
+ public final long getAndIncrement() {
+ while (true) {
+ long current = get();
+ long next = current + 1;
+ if (compareAndSet(current, next))
+ return current;
+ }
+ }
+
+ /**
+ * Atomically decrements by one the current value.
+ *
+ * @return the previous value
+ */
+ public final long getAndDecrement() {
+ while (true) {
+ long current = get();
+ long next = current - 1;
+ if (compareAndSet(current, next))
+ return current;
+ }
+ }
+
+ /**
+ * Atomically adds the given value to the current value.
+ *
+ * @param delta the value to add
+ * @return the previous value
+ */
+ public final long getAndAdd(long delta) {
+ while (true) {
+ long current = get();
+ long next = current + delta;
+ if (compareAndSet(current, next))
+ return current;
+ }
+ }
+
+ /**
+ * Atomically increments by one the current value.
+ *
+ * @return the updated value
+ */
+ public final long incrementAndGet() {
+ for (;;) {
+ long current = get();
+ long next = current + 1;
+ if (compareAndSet(current, next))
+ return next;
+ }
+ }
+
+ /**
+ * Atomically decrements by one the current value.
+ *
+ * @return the updated value
+ */
+ public final long decrementAndGet() {
+ for (;;) {
+ long current = get();
+ long next = current - 1;
+ if (compareAndSet(current, next))
+ return next;
+ }
+ }
+
+ /**
+ * Atomically adds the given value to the current value.
+ *
+ * @param delta the value to add
+ * @return the updated value
+ */
+ public final long addAndGet(long delta) {
+ for (;;) {
+ long current = get();
+ long next = current + delta;
+ if (compareAndSet(current, next))
+ return next;
+ }
+ }
+
+ /**
+ * Returns the String representation of the current value.
+ * @return the String representation of the current value.
+ */
+ public String toString() {
+ return Long.toString(get());
+ }
+
+
+ public int intValue() {
+ return (int)get();
+ }
+
+ public long longValue() {
+ return get();
+ }
+
+ public float floatValue() {
+ return (float)get();
+ }
+
+ public double doubleValue() {
+ return (double)get();
+ }
+
+}