| /* |
| * 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.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/publicdomain/zero/1.0/ |
| */ |
| |
| package java.util.concurrent.atomic; |
| |
| import java.lang.invoke.MethodHandles; |
| import java.lang.invoke.VarHandle; |
| |
| /** |
| * A {@code boolean} value that may be updated atomically. See the |
| * {@link VarHandle} specification for descriptions of the properties |
| * of atomic accesses. An {@code AtomicBoolean} is used in |
| * applications such as atomically updated flags, and cannot be used |
| * as a replacement for a {@link java.lang.Boolean}. |
| * |
| * @since 1.5 |
| * @author Doug Lea |
| */ |
| public class AtomicBoolean implements java.io.Serializable { |
| private static final long serialVersionUID = 4654671469794556979L; |
| private static final VarHandle VALUE; |
| static { |
| try { |
| MethodHandles.Lookup l = MethodHandles.lookup(); |
| VALUE = l.findVarHandle(AtomicBoolean.class, "value", int.class); |
| } catch (ReflectiveOperationException e) { |
| throw new ExceptionInInitializerError(e); |
| } |
| } |
| |
| private volatile int value; |
| |
| /** |
| * Creates a new {@code AtomicBoolean} with the given initial value. |
| * |
| * @param initialValue the initial value |
| */ |
| public AtomicBoolean(boolean initialValue) { |
| value = initialValue ? 1 : 0; |
| } |
| |
| /** |
| * Creates a new {@code AtomicBoolean} with initial value {@code false}. |
| */ |
| public AtomicBoolean() { |
| } |
| |
| /** |
| * Returns the current value, |
| * with memory effects as specified by {@link VarHandle#getVolatile}. |
| * |
| * @return the current value |
| */ |
| public final boolean get() { |
| return value != 0; |
| } |
| |
| /** |
| * Atomically sets the value to {@code newValue} |
| * if the current value {@code == expectedValue}, |
| * with memory effects as specified by {@link VarHandle#compareAndSet}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return {@code true} if successful. False return indicates that |
| * the actual value was not equal to the expected value. |
| */ |
| public final boolean compareAndSet(boolean expectedValue, boolean newValue) { |
| return VALUE.compareAndSet(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)); |
| } |
| |
| /** |
| * Possibly atomically sets the value to {@code newValue} |
| * if the current value {@code == expectedValue}, |
| * with memory effects as specified by {@link VarHandle#weakCompareAndSetPlain}. |
| * |
| * @deprecated This method has plain memory effects but the method |
| * name implies volatile memory effects (see methods such as |
| * {@link #compareAndExchange} and {@link #compareAndSet}). To avoid |
| * confusion over plain or volatile memory effects it is recommended that |
| * the method {@link #weakCompareAndSetPlain} be used instead. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return {@code true} if successful |
| * @see #weakCompareAndSetPlain |
| */ |
| @Deprecated(since="9") |
| public boolean weakCompareAndSet(boolean expectedValue, boolean newValue) { |
| return VALUE.weakCompareAndSetPlain(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)); |
| } |
| |
| /** |
| * Possibly atomically sets the value to {@code newValue} |
| * if the current value {@code == expectedValue}, |
| * with memory effects as specified by {@link VarHandle#weakCompareAndSetPlain}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return {@code true} if successful |
| * @since 9 |
| */ |
| public boolean weakCompareAndSetPlain(boolean expectedValue, boolean newValue) { |
| return VALUE.weakCompareAndSetPlain(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)); |
| } |
| |
| /** |
| * Sets the value to {@code newValue}, |
| * with memory effects as specified by {@link VarHandle#setVolatile}. |
| * |
| * @param newValue the new value |
| */ |
| public final void set(boolean newValue) { |
| value = newValue ? 1 : 0; |
| } |
| |
| /** |
| * Sets the value to {@code newValue}, |
| * with memory effects as specified by {@link VarHandle#setRelease}. |
| * |
| * @param newValue the new value |
| * @since 1.6 |
| */ |
| public final void lazySet(boolean newValue) { |
| VALUE.setRelease(this, (newValue ? 1 : 0)); |
| } |
| |
| /** |
| * Atomically sets the value to {@code newValue} and returns the old value, |
| * with memory effects as specified by {@link VarHandle#getAndSet}. |
| * |
| * @param newValue the new value |
| * @return the previous value |
| */ |
| public final boolean getAndSet(boolean newValue) { |
| return (int)VALUE.getAndSet(this, (newValue ? 1 : 0)) != 0; |
| } |
| |
| /** |
| * Returns the String representation of the current value. |
| * @return the String representation of the current value |
| */ |
| public String toString() { |
| return Boolean.toString(get()); |
| } |
| |
| // jdk9 |
| |
| /** |
| * Returns the current value, with memory semantics of reading as |
| * if the variable was declared non-{@code volatile}. |
| * |
| * @return the value |
| * @since 9 |
| */ |
| public final boolean getPlain() { |
| return (int)VALUE.get(this) != 0; |
| } |
| |
| /** |
| * Sets the value to {@code newValue}, with memory semantics |
| * of setting as if the variable was declared non-{@code volatile} |
| * and non-{@code final}. |
| * |
| * @param newValue the new value |
| * @since 9 |
| */ |
| public final void setPlain(boolean newValue) { |
| VALUE.set(this, newValue ? 1 : 0); |
| } |
| |
| /** |
| * Returns the current value, |
| * with memory effects as specified by {@link VarHandle#getOpaque}. |
| * |
| * @return the value |
| * @since 9 |
| */ |
| public final boolean getOpaque() { |
| return (int)VALUE.getOpaque(this) != 0; |
| } |
| |
| /** |
| * Sets the value to {@code newValue}, |
| * with memory effects as specified by {@link VarHandle#setOpaque}. |
| * |
| * @param newValue the new value |
| * @since 9 |
| */ |
| public final void setOpaque(boolean newValue) { |
| VALUE.setOpaque(this, newValue ? 1 : 0); |
| } |
| |
| /** |
| * Returns the current value, |
| * with memory effects as specified by {@link VarHandle#getAcquire}. |
| * |
| * @return the value |
| * @since 9 |
| */ |
| public final boolean getAcquire() { |
| return (int)VALUE.getAcquire(this) != 0; |
| } |
| |
| /** |
| * Sets the value to {@code newValue}, |
| * with memory effects as specified by {@link VarHandle#setRelease}. |
| * |
| * @param newValue the new value |
| * @since 9 |
| */ |
| public final void setRelease(boolean newValue) { |
| VALUE.setRelease(this, newValue ? 1 : 0); |
| } |
| |
| /** |
| * Atomically sets the value to {@code newValue} if the current value, |
| * referred to as the <em>witness value</em>, {@code == expectedValue}, |
| * with memory effects as specified by |
| * {@link VarHandle#compareAndExchange}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return the witness value, which will be the same as the |
| * expected value if successful |
| * @since 9 |
| */ |
| public final boolean compareAndExchange(boolean expectedValue, boolean newValue) { |
| return (int)VALUE.compareAndExchange(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)) != 0; |
| } |
| |
| /** |
| * Atomically sets the value to {@code newValue} if the current value, |
| * referred to as the <em>witness value</em>, {@code == expectedValue}, |
| * with memory effects as specified by |
| * {@link VarHandle#compareAndExchangeAcquire}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return the witness value, which will be the same as the |
| * expected value if successful |
| * @since 9 |
| */ |
| public final boolean compareAndExchangeAcquire(boolean expectedValue, boolean newValue) { |
| return (int)VALUE.compareAndExchangeAcquire(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)) != 0; |
| } |
| |
| /** |
| * Atomically sets the value to {@code newValue} if the current value, |
| * referred to as the <em>witness value</em>, {@code == expectedValue}, |
| * with memory effects as specified by |
| * {@link VarHandle#compareAndExchangeRelease}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return the witness value, which will be the same as the |
| * expected value if successful |
| * @since 9 |
| */ |
| public final boolean compareAndExchangeRelease(boolean expectedValue, boolean newValue) { |
| return (int)VALUE.compareAndExchangeRelease(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)) != 0; |
| } |
| |
| /** |
| * Possibly atomically sets the value to {@code newValue} if the current |
| * value {@code == expectedValue}, |
| * with memory effects as specified by |
| * {@link VarHandle#weakCompareAndSet}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return {@code true} if successful |
| * @since 9 |
| */ |
| public final boolean weakCompareAndSetVolatile(boolean expectedValue, boolean newValue) { |
| return VALUE.weakCompareAndSet(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)); |
| } |
| |
| /** |
| * Possibly atomically sets the value to {@code newValue} if the current |
| * value {@code == expectedValue}, |
| * with memory effects as specified by |
| * {@link VarHandle#weakCompareAndSetAcquire}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return {@code true} if successful |
| * @since 9 |
| */ |
| public final boolean weakCompareAndSetAcquire(boolean expectedValue, boolean newValue) { |
| return VALUE.weakCompareAndSetAcquire(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)); |
| } |
| |
| /** |
| * Possibly atomically sets the value to {@code newValue} if the current |
| * value {@code == expectedValue}, |
| * with memory effects as specified by |
| * {@link VarHandle#weakCompareAndSetRelease}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return {@code true} if successful |
| * @since 9 |
| */ |
| public final boolean weakCompareAndSetRelease(boolean expectedValue, boolean newValue) { |
| return VALUE.weakCompareAndSetRelease(this, |
| (expectedValue ? 1 : 0), |
| (newValue ? 1 : 0)); |
| } |
| |
| } |
