611 lines
22 KiB
Java
611 lines
22 KiB
Java
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* This file is available under and governed by the GNU General Public
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* License version 2 only, as published by the Free Software Foundation.
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* However, the following notice accompanied the original version of this
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* file:
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*
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* Written by Doug Lea with assistance from members of JCP JSR-166
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* Expert Group and released to the public domain, as explained at
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* http://creativecommons.org/publicdomain/zero/1.0/
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*/
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package java.util.concurrent.atomic;
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import java.lang.invoke.MethodHandles;
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import java.lang.invoke.VarHandle;
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import java.util.function.IntBinaryOperator;
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import java.util.function.IntUnaryOperator;
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/**
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* An {@code int} value that may be updated atomically. See the
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* {@link VarHandle} specification for descriptions of the properties
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* of atomic accesses. An {@code AtomicInteger} is used in
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* applications such as atomically incremented counters, and cannot be
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* used as a replacement for an {@link java.lang.Integer}. However,
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* this class does extend {@code Number} to allow uniform access by
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* tools and utilities that deal with numerically-based classes.
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*
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* @since 1.5
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* @author Doug Lea
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*/
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public class AtomicInteger extends Number implements java.io.Serializable {
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private static final long serialVersionUID = 6214790243416807050L;
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/*
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* This class intended to be implemented using VarHandles, but there
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* are unresolved cyclic startup dependencies.
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*/
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// BEGIN Android-changed: Using VarHandle instead of Unsafe
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// private static final Unsafe U = Unsafe.getUnsafe();
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// private static final long VALUE
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// = U.objectFieldOffset(AtomicInteger.class, "value");
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private static final VarHandle VALUE;
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static {
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try {
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MethodHandles.Lookup l = MethodHandles.lookup();
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VALUE = l.findVarHandle(AtomicInteger.class, "value", int.class);
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} catch (ReflectiveOperationException e) {
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throw new ExceptionInInitializerError(e);
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}
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}
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// END Android-changed: Using VarHandle instead of Unsafe
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private volatile int value;
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/**
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* Creates a new AtomicInteger with the given initial value.
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*
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* @param initialValue the initial value
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*/
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public AtomicInteger(int initialValue) {
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value = initialValue;
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}
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/**
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* Creates a new AtomicInteger with initial value {@code 0}.
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*/
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public AtomicInteger() {
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}
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/**
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* Returns the current value,
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* with memory effects as specified by {@link VarHandle#getVolatile}.
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*
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* @return the current value
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*/
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public final int get() {
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return value;
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}
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/**
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* Sets the value to {@code newValue},
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* with memory effects as specified by {@link VarHandle#setVolatile}.
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*
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* @param newValue the new value
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*/
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public final void set(int newValue) {
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value = newValue;
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}
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/**
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* Sets the value to {@code newValue},
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* with memory effects as specified by {@link VarHandle#setRelease}.
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*
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* @param newValue the new value
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* @since 1.6
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*/
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public final void lazySet(int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// U.putIntRelease(this, VALUE, newValue);
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VALUE.setRelease(this, newValue);
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}
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/**
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* Atomically sets the value to {@code newValue} and returns the old value,
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* with memory effects as specified by {@link VarHandle#getAndSet}.
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*
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* @param newValue the new value
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* @return the previous value
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*/
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public final int getAndSet(int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getAndSetInt(this, VALUE, newValue);
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return (int)VALUE.getAndSet(this, newValue);
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}
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/**
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* Atomically sets the value to {@code newValue}
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* if the current value {@code == expectedValue},
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* with memory effects as specified by {@link VarHandle#compareAndSet}.
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*
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* @param expectedValue the expected value
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* @param newValue the new value
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* @return {@code true} if successful. False return indicates that
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* the actual value was not equal to the expected value.
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*/
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public final boolean compareAndSet(int expectedValue, int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.compareAndSetInt(this, VALUE, expectedValue, newValue);
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return VALUE.compareAndSet(this, expectedValue, newValue);
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}
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/**
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* Possibly atomically sets the value to {@code newValue}
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* if the current value {@code == expectedValue},
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* with memory effects as specified by {@link VarHandle#weakCompareAndSetPlain}.
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*
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* @deprecated This method has plain memory effects but the method
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* name implies volatile memory effects (see methods such as
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* {@link #compareAndExchange} and {@link #compareAndSet}). To avoid
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* confusion over plain or volatile memory effects it is recommended that
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* the method {@link #weakCompareAndSetPlain} be used instead.
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*
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* @param expectedValue the expected value
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* @param newValue the new value
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* @return {@code true} if successful
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* @see #weakCompareAndSetPlain
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*/
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@Deprecated(since="9")
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public final boolean weakCompareAndSet(int expectedValue, int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.weakCompareAndSetIntPlain(this, VALUE, expectedValue, newValue);
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return VALUE.weakCompareAndSetPlain(this, expectedValue, newValue);
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}
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/**
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* Possibly atomically sets the value to {@code newValue}
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* if the current value {@code == expectedValue},
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* with memory effects as specified by {@link VarHandle#weakCompareAndSetPlain}.
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*
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* @param expectedValue the expected value
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* @param newValue the new value
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* @return {@code true} if successful
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* @since 9
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*/
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public final boolean weakCompareAndSetPlain(int expectedValue, int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.weakCompareAndSetIntPlain(this, VALUE, expectedValue, newValue);
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return VALUE.weakCompareAndSetPlain(this, expectedValue, newValue);
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}
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/**
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* Atomically increments the current value,
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* with memory effects as specified by {@link VarHandle#getAndAdd}.
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*
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* <p>Equivalent to {@code getAndAdd(1)}.
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*
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* @return the previous value
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*/
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public final int getAndIncrement() {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getAndAddInt(this, VALUE, 1);
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return (int)VALUE.getAndAdd(this, 1);
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}
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/**
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* Atomically decrements the current value,
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* with memory effects as specified by {@link VarHandle#getAndAdd}.
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*
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* <p>Equivalent to {@code getAndAdd(-1)}.
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*
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* @return the previous value
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*/
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public final int getAndDecrement() {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getAndAddInt(this, VALUE, -1);
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return (int)VALUE.getAndAdd(this, -1);
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}
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/**
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* Atomically adds the given value to the current value,
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* with memory effects as specified by {@link VarHandle#getAndAdd}.
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*
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* @param delta the value to add
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* @return the previous value
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*/
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public final int getAndAdd(int delta) {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getAndAddInt(this, VALUE, delta);
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return (int)VALUE.getAndAdd(this, delta);
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}
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/**
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* Atomically increments the current value,
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* with memory effects as specified by {@link VarHandle#getAndAdd}.
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*
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* <p>Equivalent to {@code addAndGet(1)}.
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*
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* @return the updated value
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*/
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public final int incrementAndGet() {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getAndAddInt(this, VALUE, 1) + 1;
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return (int)VALUE.getAndAdd(this, 1) + 1;
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}
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/**
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* Atomically decrements the current value,
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* with memory effects as specified by {@link VarHandle#getAndAdd}.
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*
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* <p>Equivalent to {@code addAndGet(-1)}.
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*
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* @return the updated value
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*/
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public final int decrementAndGet() {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getAndAddInt(this, VALUE, -1) - 1;
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return (int)VALUE.getAndAdd(this, -1) - 1;
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}
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/**
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* Atomically adds the given value to the current value,
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* with memory effects as specified by {@link VarHandle#getAndAdd}.
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*
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* @param delta the value to add
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* @return the updated value
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*/
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public final int addAndGet(int delta) {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getAndAddInt(this, VALUE, delta) + delta;
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return (int)VALUE.getAndAdd(this, delta) + delta;
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}
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/**
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* Atomically updates (with memory effects as specified by {@link
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* VarHandle#compareAndSet}) the current value with the results of
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* applying the given function, returning the previous value. The
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* function should be side-effect-free, since it may be re-applied
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* when attempted updates fail due to contention among threads.
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*
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* @param updateFunction a side-effect-free function
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* @return the previous value
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* @since 1.8
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*/
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public final int getAndUpdate(IntUnaryOperator updateFunction) {
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int prev = get(), next = 0;
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for (boolean haveNext = false;;) {
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if (!haveNext)
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next = updateFunction.applyAsInt(prev);
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if (weakCompareAndSetVolatile(prev, next))
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return prev;
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haveNext = (prev == (prev = get()));
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}
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}
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/**
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* Atomically updates (with memory effects as specified by {@link
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* VarHandle#compareAndSet}) the current value with the results of
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* applying the given function, returning the updated value. The
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* function should be side-effect-free, since it may be re-applied
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* when attempted updates fail due to contention among threads.
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*
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* @param updateFunction a side-effect-free function
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* @return the updated value
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* @since 1.8
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*/
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public final int updateAndGet(IntUnaryOperator updateFunction) {
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int prev = get(), next = 0;
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for (boolean haveNext = false;;) {
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if (!haveNext)
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next = updateFunction.applyAsInt(prev);
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if (weakCompareAndSetVolatile(prev, next))
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return next;
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haveNext = (prev == (prev = get()));
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}
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}
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/**
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* Atomically updates (with memory effects as specified by {@link
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* VarHandle#compareAndSet}) the current value with the results of
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* applying the given function to the current and given values,
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* returning the previous value. The function should be
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* side-effect-free, since it may be re-applied when attempted
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* updates fail due to contention among threads. The function is
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* applied with the current value as its first argument, and the
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* given update as the second argument.
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*
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* @param x the update value
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* @param accumulatorFunction a side-effect-free function of two arguments
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* @return the previous value
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* @since 1.8
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*/
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public final int getAndAccumulate(int x,
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IntBinaryOperator accumulatorFunction) {
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int prev = get(), next = 0;
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for (boolean haveNext = false;;) {
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if (!haveNext)
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next = accumulatorFunction.applyAsInt(prev, x);
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if (weakCompareAndSetVolatile(prev, next))
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return prev;
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haveNext = (prev == (prev = get()));
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}
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}
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/**
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* Atomically updates (with memory effects as specified by {@link
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* VarHandle#compareAndSet}) the current value with the results of
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* applying the given function to the current and given values,
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* returning the updated value. The function should be
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* side-effect-free, since it may be re-applied when attempted
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* updates fail due to contention among threads. The function is
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* applied with the current value as its first argument, and the
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* given update as the second argument.
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*
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* @param x the update value
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* @param accumulatorFunction a side-effect-free function of two arguments
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* @return the updated value
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* @since 1.8
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*/
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public final int accumulateAndGet(int x,
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IntBinaryOperator accumulatorFunction) {
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int prev = get(), next = 0;
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for (boolean haveNext = false;;) {
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if (!haveNext)
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next = accumulatorFunction.applyAsInt(prev, x);
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if (weakCompareAndSetVolatile(prev, next))
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return next;
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haveNext = (prev == (prev = get()));
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}
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}
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/**
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* Returns the String representation of the current value.
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* @return the String representation of the current value
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*/
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public String toString() {
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return Integer.toString(get());
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}
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/**
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* Returns the current value of this {@code AtomicInteger} as an
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* {@code int},
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* with memory effects as specified by {@link VarHandle#getVolatile}.
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*
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* Equivalent to {@link #get()}.
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*/
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public int intValue() {
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return get();
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}
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/**
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* Returns the current value of this {@code AtomicInteger} as a
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* {@code long} after a widening primitive conversion,
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* with memory effects as specified by {@link VarHandle#getVolatile}.
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* @jls 5.1.2 Widening Primitive Conversion
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*/
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public long longValue() {
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return (long)get();
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}
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/**
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* Returns the current value of this {@code AtomicInteger} as a
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* {@code float} after a widening primitive conversion,
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* with memory effects as specified by {@link VarHandle#getVolatile}.
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* @jls 5.1.2 Widening Primitive Conversion
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*/
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public float floatValue() {
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return (float)get();
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}
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/**
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* Returns the current value of this {@code AtomicInteger} as a
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* {@code double} after a widening primitive conversion,
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* with memory effects as specified by {@link VarHandle#getVolatile}.
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* @jls 5.1.2 Widening Primitive Conversion
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*/
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public double doubleValue() {
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return (double)get();
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}
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// jdk9
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/**
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* Returns the current value, with memory semantics of reading as
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* if the variable was declared non-{@code volatile}.
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*
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* @return the value
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* @since 9
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*/
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public final int getPlain() {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getInt(this, VALUE);
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return (int)VALUE.get(this);
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}
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/**
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* Sets the value to {@code newValue}, with memory semantics
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* of setting as if the variable was declared non-{@code volatile}
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* and non-{@code final}.
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*
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* @param newValue the new value
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* @since 9
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*/
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public final void setPlain(int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// U.putInt(this, VALUE, newValue);
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VALUE.set(this, newValue);
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}
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/**
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* Returns the current value,
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* with memory effects as specified by {@link VarHandle#getOpaque}.
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*
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* @return the value
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* @since 9
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*/
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public final int getOpaque() {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getIntOpaque(this, VALUE);
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return (int)VALUE.getOpaque(this);
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}
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/**
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* Sets the value to {@code newValue},
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* with memory effects as specified by {@link VarHandle#setOpaque}.
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*
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* @param newValue the new value
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* @since 9
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*/
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public final void setOpaque(int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// U.putIntOpaque(this, VALUE, newValue);
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VALUE.setOpaque(this, newValue);
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}
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/**
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* Returns the current value,
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* with memory effects as specified by {@link VarHandle#getAcquire}.
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*
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* @return the value
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* @since 9
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*/
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public final int getAcquire() {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.getIntAcquire(this, VALUE);
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return (int)VALUE.getAcquire(this);
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}
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/**
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* Sets the value to {@code newValue},
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* with memory effects as specified by {@link VarHandle#setRelease}.
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*
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* @param newValue the new value
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* @since 9
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*/
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public final void setRelease(int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// U.putIntRelease(this, VALUE, newValue);
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VALUE.setRelease(this, newValue);
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}
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/**
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* Atomically sets the value to {@code newValue} if the current value,
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* referred to as the <em>witness value</em>, {@code == expectedValue},
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* with memory effects as specified by
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* {@link VarHandle#compareAndExchange}.
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*
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* @param expectedValue the expected value
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* @param newValue the new value
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* @return the witness value, which will be the same as the
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* expected value if successful
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* @since 9
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*/
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public final int compareAndExchange(int expectedValue, int newValue) {
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// Android-changed: Using VarHandle instead of Unsafe
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// return U.compareAndExchangeInt(this, VALUE, expectedValue, newValue);
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return (int)VALUE.compareAndExchange(this, expectedValue, newValue);
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}
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/**
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* Atomically sets the value to {@code newValue} if the current value,
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* 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 int compareAndExchangeAcquire(int expectedValue, int newValue) {
|
|
// Android-changed: Using VarHandle instead of Unsafe
|
|
// return U.compareAndExchangeIntAcquire(this, VALUE, expectedValue, newValue);
|
|
return (int)VALUE.compareAndExchangeAcquire(this, expectedValue, newValue);
|
|
}
|
|
|
|
/**
|
|
* 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 int compareAndExchangeRelease(int expectedValue, int newValue) {
|
|
// Android-changed: Using VarHandle instead of Unsafe
|
|
// return U.compareAndExchangeIntRelease(this, VALUE, expectedValue, newValue);
|
|
return (int)VALUE.compareAndExchangeRelease(this, expectedValue, newValue);
|
|
}
|
|
|
|
/**
|
|
* 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(int expectedValue, int newValue) {
|
|
// Android-changed: Using VarHandle instead of Unsafe
|
|
//return U.weakCompareAndSetInt(this, VALUE, expectedValue, newValue);
|
|
return VALUE.weakCompareAndSet(this, expectedValue, newValue);
|
|
}
|
|
|
|
/**
|
|
* 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(int expectedValue, int newValue) {
|
|
// Android-changed: Using VarHandle instead of Unsafe
|
|
// return U.weakCompareAndSetIntAcquire(this, VALUE, expectedValue, newValue);
|
|
return VALUE.weakCompareAndSetAcquire(this, expectedValue, newValue);
|
|
}
|
|
|
|
/**
|
|
* 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(int expectedValue, int newValue) {
|
|
// Android-changed: Using VarHandle instead of Unsafe
|
|
// return U.weakCompareAndSetIntRelease(this, VALUE, expectedValue, newValue);
|
|
return VALUE.weakCompareAndSetRelease(this, expectedValue, newValue);
|
|
}
|
|
|
|
}
|