feat(jdk8): move files to new folder to avoid resources compiled.
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350
jdkSrc/jdk8/java/util/concurrent/atomic/AtomicLong.java
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350
jdkSrc/jdk8/java/util/concurrent/atomic/AtomicLong.java
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/*
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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.util.function.LongUnaryOperator;
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import java.util.function.LongBinaryOperator;
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import sun.misc.Unsafe;
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/**
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* A {@code long} value that may be updated atomically. See the
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* {@link java.util.concurrent.atomic} package specification for
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* description of the properties of atomic variables. An
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* {@code AtomicLong} is used in applications such as atomically
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* incremented sequence numbers, and cannot be used as a replacement
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* for a {@link java.lang.Long}. However, this class does extend
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* {@code Number} to allow uniform access by tools and utilities that
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* 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 AtomicLong extends Number implements java.io.Serializable {
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private static final long serialVersionUID = 1927816293512124184L;
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// setup to use Unsafe.compareAndSwapLong for updates
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private static final Unsafe unsafe = Unsafe.getUnsafe();
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private static final long valueOffset;
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/**
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* Records whether the underlying JVM supports lockless
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* compareAndSwap for longs. While the Unsafe.compareAndSwapLong
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* method works in either case, some constructions should be
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* handled at Java level to avoid locking user-visible locks.
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*/
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static final boolean VM_SUPPORTS_LONG_CAS = VMSupportsCS8();
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/**
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* Returns whether underlying JVM supports lockless CompareAndSet
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* for longs. Called only once and cached in VM_SUPPORTS_LONG_CAS.
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*/
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private static native boolean VMSupportsCS8();
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static {
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try {
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valueOffset = unsafe.objectFieldOffset
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(AtomicLong.class.getDeclaredField("value"));
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} catch (Exception ex) { throw new Error(ex); }
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}
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private volatile long value;
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/**
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* Creates a new AtomicLong 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 AtomicLong(long initialValue) {
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value = initialValue;
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}
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/**
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* Creates a new AtomicLong with initial value {@code 0}.
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*/
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public AtomicLong() {
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}
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/**
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* Gets the current value.
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*
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* @return the current value
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*/
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public final long get() {
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return value;
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}
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/**
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* Sets to the given value.
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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(long newValue) {
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value = newValue;
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}
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/**
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* Eventually sets to the given value.
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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(long newValue) {
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unsafe.putOrderedLong(this, valueOffset, newValue);
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}
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/**
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* Atomically sets to the given value and returns the old value.
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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 long getAndSet(long newValue) {
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return unsafe.getAndSetLong(this, valueOffset, newValue);
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}
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/**
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* Atomically sets the value to the given updated value
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* if the current value {@code ==} the expected value.
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*
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* @param expect the expected value
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* @param update 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(long expect, long update) {
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return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
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}
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/**
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* Atomically sets the value to the given updated value
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* if the current value {@code ==} the expected value.
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*
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* <p><a href="package-summary.html#weakCompareAndSet">May fail
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* spuriously and does not provide ordering guarantees</a>, so is
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* only rarely an appropriate alternative to {@code compareAndSet}.
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*
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* @param expect the expected value
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* @param update the new value
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* @return {@code true} if successful
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*/
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public final boolean weakCompareAndSet(long expect, long update) {
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return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
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}
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/**
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* Atomically increments by one the current value.
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*
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* @return the previous value
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*/
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public final long getAndIncrement() {
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return unsafe.getAndAddLong(this, valueOffset, 1L);
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}
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/**
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* Atomically decrements by one the current value.
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*
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* @return the previous value
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*/
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public final long getAndDecrement() {
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return unsafe.getAndAddLong(this, valueOffset, -1L);
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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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*
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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 long getAndAdd(long delta) {
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return unsafe.getAndAddLong(this, valueOffset, delta);
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}
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/**
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* Atomically increments by one the current value.
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*
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* @return the updated value
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*/
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public final long incrementAndGet() {
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return unsafe.getAndAddLong(this, valueOffset, 1L) + 1L;
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}
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/**
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* Atomically decrements by one the current value.
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*
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* @return the updated value
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*/
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public final long decrementAndGet() {
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return unsafe.getAndAddLong(this, valueOffset, -1L) - 1L;
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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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*
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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 long addAndGet(long delta) {
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return unsafe.getAndAddLong(this, valueOffset, delta) + delta;
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}
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/**
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* Atomically updates 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 long getAndUpdate(LongUnaryOperator updateFunction) {
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long prev, next;
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do {
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prev = get();
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next = updateFunction.applyAsLong(prev);
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} while (!compareAndSet(prev, next));
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return prev;
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}
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/**
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* Atomically updates 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 long updateAndGet(LongUnaryOperator updateFunction) {
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long prev, next;
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do {
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prev = get();
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next = updateFunction.applyAsLong(prev);
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} while (!compareAndSet(prev, next));
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return next;
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}
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/**
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* Atomically updates 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
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* is applied with the current value as its first argument,
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* and the 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 long getAndAccumulate(long x,
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LongBinaryOperator accumulatorFunction) {
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long prev, next;
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do {
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prev = get();
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next = accumulatorFunction.applyAsLong(prev, x);
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} while (!compareAndSet(prev, next));
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return prev;
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}
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/**
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* Atomically updates 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
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* is applied with the current value as its first argument,
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* and the 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 long accumulateAndGet(long x,
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LongBinaryOperator accumulatorFunction) {
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long prev, next;
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do {
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prev = get();
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next = accumulatorFunction.applyAsLong(prev, x);
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} while (!compareAndSet(prev, next));
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return next;
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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 Long.toString(get());
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}
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/**
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* Returns the value of this {@code AtomicLong} as an {@code int}
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* after a narrowing primitive conversion.
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* @jls 5.1.3 Narrowing Primitive Conversions
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*/
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public int intValue() {
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return (int)get();
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}
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/**
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* Returns the value of this {@code AtomicLong} as a {@code long}.
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*/
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public long longValue() {
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return get();
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}
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/**
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* Returns the value of this {@code AtomicLong} as a {@code float}
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* after a widening primitive conversion.
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* @jls 5.1.2 Widening Primitive Conversions
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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 value of this {@code AtomicLong} as a {@code double}
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* after a widening primitive conversion.
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* @jls 5.1.2 Widening Primitive Conversions
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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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}
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