| /* |
| * 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; |
| import java.util.function.LongBinaryOperator; |
| import java.util.function.LongUnaryOperator; |
| |
| /** |
| * A {@code long} value that may be updated atomically. See the |
| * {@link VarHandle} specification for descriptions of the properties |
| * of atomic accesses. 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; |
| |
| /** |
| * Records whether the underlying JVM supports lockless |
| * compareAndSet for longs. While the intrinsic compareAndSetLong |
| * 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(); |
| |
| /* |
| * This class intended to be implemented using VarHandles, but there |
| * are unresolved cyclic startup dependencies. |
| */ |
| // BEGIN Android-changed: Using VarHandle instead of Unsafe |
| // private static final Unsafe U = Unsafe.getUnsafe(); |
| // private static final long VALUE |
| // = U.objectFieldOffset(AtomicLong.class, "value"); |
| private static final VarHandle VALUE; |
| static { |
| try { |
| MethodHandles.Lookup l = MethodHandles.lookup(); |
| VALUE = l.findVarHandle(AtomicLong.class, "value", long.class); |
| } catch (ReflectiveOperationException e) { |
| throw new ExceptionInInitializerError(e); |
| } |
| } |
| // END Android-changed: Using VarHandle instead of Unsafe |
| |
| 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() { |
| } |
| |
| /** |
| * Returns the current value, |
| * with memory effects as specified by {@link VarHandle#getVolatile}. |
| * |
| * @return the current value |
| */ |
| public final long get() { |
| return value; |
| } |
| |
| /** |
| * Sets the value to {@code newValue}, |
| * with memory effects as specified by {@link VarHandle#setVolatile}. |
| * |
| * @param newValue the new value |
| */ |
| public final void set(long newValue) { |
| // See JDK-8180620: Clarify VarHandle mixed-access subtleties |
| // Android-changed: Using VarHandle instead of Unsafe |
| // U.putLongVolatile(this, VALUE, newValue); |
| VALUE.setVolatile(this, newValue); |
| } |
| |
| /** |
| * 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(long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // U.putLongRelease(this, VALUE, newValue); |
| VALUE.setRelease(this, newValue); |
| } |
| |
| /** |
| * 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 long getAndSet(long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getAndSetLong(this, VALUE, newValue); |
| return (long)VALUE.getAndSet(this, newValue); |
| } |
| |
| /** |
| * 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(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.compareAndSetLong(this, VALUE, expectedValue, newValue); |
| return VALUE.compareAndSet(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#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 final boolean weakCompareAndSet(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.weakCompareAndSetLongPlain(this, VALUE, expectedValue, newValue); |
| return VALUE.weakCompareAndSetPlain(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#weakCompareAndSetPlain}. |
| * |
| * @param expectedValue the expected value |
| * @param newValue the new value |
| * @return {@code true} if successful |
| * @since 9 |
| */ |
| public final boolean weakCompareAndSetPlain(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.weakCompareAndSetLongPlain(this, VALUE, expectedValue, newValue); |
| return VALUE.weakCompareAndSetPlain(this, expectedValue, newValue); |
| } |
| |
| /** |
| * Atomically increments the current value, |
| * with memory effects as specified by {@link VarHandle#getAndAdd}. |
| * |
| * <p>Equivalent to {@code getAndAdd(1)}. |
| * |
| * @return the previous value |
| */ |
| public final long getAndIncrement() { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getAndAddLong(this, VALUE, 1L); |
| return (long)VALUE.getAndAdd(this, 1L); |
| } |
| |
| /** |
| * Atomically decrements the current value, |
| * with memory effects as specified by {@link VarHandle#getAndAdd}. |
| * |
| * <p>Equivalent to {@code getAndAdd(-1)}. |
| * |
| * @return the previous value |
| */ |
| public final long getAndDecrement() { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getAndAddLong(this, VALUE, -1L); |
| return (long)VALUE.getAndAdd(this, -1L); |
| } |
| |
| /** |
| * Atomically adds the given value to the current value, |
| * with memory effects as specified by {@link VarHandle#getAndAdd}. |
| * |
| * @param delta the value to add |
| * @return the previous value |
| */ |
| public final long getAndAdd(long delta) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getAndAddLong(this, VALUE, delta); |
| return (long)VALUE.getAndAdd(this, delta); |
| } |
| |
| /** |
| * Atomically increments the current value, |
| * with memory effects as specified by {@link VarHandle#getAndAdd}. |
| * |
| * <p>Equivalent to {@code addAndGet(1)}. |
| * |
| * @return the updated value |
| */ |
| public final long incrementAndGet() { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getAndAddLong(this, VALUE, 1L) + 1L; |
| return (long)VALUE.getAndAdd(this, 1L) + 1L; |
| } |
| |
| /** |
| * Atomically decrements the current value, |
| * with memory effects as specified by {@link VarHandle#getAndAdd}. |
| * |
| * <p>Equivalent to {@code addAndGet(-1)}. |
| * |
| * @return the updated value |
| */ |
| public final long decrementAndGet() { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getAndAddLong(this, VALUE, -1L) - 1L; |
| return (long)VALUE.getAndAdd(this, -1L) - 1L; |
| } |
| |
| /** |
| * Atomically adds the given value to the current value, |
| * with memory effects as specified by {@link VarHandle#getAndAdd}. |
| * |
| * @param delta the value to add |
| * @return the updated value |
| */ |
| public final long addAndGet(long delta) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getAndAddLong(this, VALUE, delta) + delta; |
| return (long)VALUE.getAndAdd(this, delta) + delta; |
| } |
| |
| /** |
| * Atomically updates (with memory effects as specified by {@link |
| * VarHandle#compareAndSet}) the current value with the results of |
| * applying the given function, returning the previous value. The |
| * function should be side-effect-free, since it may be re-applied |
| * when attempted updates fail due to contention among threads. |
| * |
| * @param updateFunction a side-effect-free function |
| * @return the previous value |
| * @since 1.8 |
| */ |
| public final long getAndUpdate(LongUnaryOperator updateFunction) { |
| long prev = get(), next = 0L; |
| for (boolean haveNext = false;;) { |
| if (!haveNext) |
| next = updateFunction.applyAsLong(prev); |
| if (weakCompareAndSetVolatile(prev, next)) |
| return prev; |
| haveNext = (prev == (prev = get())); |
| } |
| } |
| |
| /** |
| * Atomically updates (with memory effects as specified by {@link |
| * VarHandle#compareAndSet}) the current value with the results of |
| * applying the given function, returning the updated value. The |
| * function should be side-effect-free, since it may be re-applied |
| * when attempted updates fail due to contention among threads. |
| * |
| * @param updateFunction a side-effect-free function |
| * @return the updated value |
| * @since 1.8 |
| */ |
| public final long updateAndGet(LongUnaryOperator updateFunction) { |
| long prev = get(), next = 0L; |
| for (boolean haveNext = false;;) { |
| if (!haveNext) |
| next = updateFunction.applyAsLong(prev); |
| if (weakCompareAndSetVolatile(prev, next)) |
| return next; |
| haveNext = (prev == (prev = get())); |
| } |
| } |
| |
| /** |
| * Atomically updates (with memory effects as specified by {@link |
| * VarHandle#compareAndSet}) the current value with the results of |
| * applying the given function to the current and given values, |
| * returning the previous value. The function should be |
| * side-effect-free, since it may be re-applied when attempted |
| * updates fail due to contention among threads. The function is |
| * applied with the current value as its first argument, and the |
| * given update as the second argument. |
| * |
| * @param x the update value |
| * @param accumulatorFunction a side-effect-free function of two arguments |
| * @return the previous value |
| * @since 1.8 |
| */ |
| public final long getAndAccumulate(long x, |
| LongBinaryOperator accumulatorFunction) { |
| long prev = get(), next = 0L; |
| for (boolean haveNext = false;;) { |
| if (!haveNext) |
| next = accumulatorFunction.applyAsLong(prev, x); |
| if (weakCompareAndSetVolatile(prev, next)) |
| return prev; |
| haveNext = (prev == (prev = get())); |
| } |
| } |
| |
| /** |
| * Atomically updates (with memory effects as specified by {@link |
| * VarHandle#compareAndSet}) the current value with the results of |
| * applying the given function to the current and given values, |
| * returning the updated value. The function should be |
| * side-effect-free, since it may be re-applied when attempted |
| * updates fail due to contention among threads. The function is |
| * applied with the current value as its first argument, and the |
| * given update as the second argument. |
| * |
| * @param x the update value |
| * @param accumulatorFunction a side-effect-free function of two arguments |
| * @return the updated value |
| * @since 1.8 |
| */ |
| public final long accumulateAndGet(long x, |
| LongBinaryOperator accumulatorFunction) { |
| long prev = get(), next = 0L; |
| for (boolean haveNext = false;;) { |
| if (!haveNext) |
| next = accumulatorFunction.applyAsLong(prev, x); |
| if (weakCompareAndSetVolatile(prev, next)) |
| return next; |
| haveNext = (prev == (prev = get())); |
| } |
| } |
| |
| /** |
| * Returns the String representation of the current value. |
| * @return the String representation of the current value |
| */ |
| public String toString() { |
| return Long.toString(get()); |
| } |
| |
| /** |
| * Returns the current value of this {@code AtomicLong} as an {@code int} |
| * after a narrowing primitive conversion, |
| * with memory effects as specified by {@link VarHandle#getVolatile}. |
| * @jls 5.1.3 Narrowing Primitive Conversion |
| */ |
| public int intValue() { |
| return (int)get(); |
| } |
| |
| /** |
| * Returns the current value of this {@code AtomicLong} as a {@code long}, |
| * with memory effects as specified by {@link VarHandle#getVolatile}. |
| * Equivalent to {@link #get()}. |
| */ |
| public long longValue() { |
| return get(); |
| } |
| |
| /** |
| * Returns the current value of this {@code AtomicLong} as a {@code float} |
| * after a widening primitive conversion, |
| * with memory effects as specified by {@link VarHandle#getVolatile}. |
| * @jls 5.1.2 Widening Primitive Conversion |
| */ |
| public float floatValue() { |
| return (float)get(); |
| } |
| |
| /** |
| * Returns the current value of this {@code AtomicLong} as a {@code double} |
| * after a widening primitive conversion, |
| * with memory effects as specified by {@link VarHandle#getVolatile}. |
| * @jls 5.1.2 Widening Primitive Conversion |
| */ |
| public double doubleValue() { |
| return (double)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 long getPlain() { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getLong(this, VALUE); |
| return (long)VALUE.get(this); |
| } |
| |
| /** |
| * 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(long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // U.putLong(this, VALUE, newValue); |
| VALUE.set(this, newValue); |
| } |
| |
| /** |
| * Returns the current value, |
| * with memory effects as specified by {@link VarHandle#getOpaque}. |
| * |
| * @return the value |
| * @since 9 |
| */ |
| public final long getOpaque() { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getLongOpaque(this, VALUE); |
| return (long)VALUE.getOpaque(this); |
| } |
| |
| /** |
| * 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(long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // U.putLongOpaque(this, VALUE, newValue); |
| VALUE.setOpaque(this, newValue); |
| } |
| |
| /** |
| * Returns the current value, |
| * with memory effects as specified by {@link VarHandle#getAcquire}. |
| * |
| * @return the value |
| * @since 9 |
| */ |
| public final long getAcquire() { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.getLongAcquire(this, VALUE); |
| return (long)VALUE.getAcquire(this); |
| } |
| |
| /** |
| * 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(long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // U.putLongRelease(this, VALUE, newValue); |
| VALUE.setRelease(this, 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#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 long compareAndExchange(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.compareAndExchangeLong(this, VALUE, expectedValue, newValue); |
| return (long)VALUE.compareAndExchange(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#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 long compareAndExchangeAcquire(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.compareAndExchangeLongAcquire(this, VALUE, expectedValue, newValue); |
| return (long)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 long compareAndExchangeRelease(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.compareAndExchangeLongRelease(this, VALUE, expectedValue, newValue); |
| return (long)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(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.weakCompareAndSetLong(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(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.weakCompareAndSetLongAcquire(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(long expectedValue, long newValue) { |
| // Android-changed: Using VarHandle instead of Unsafe |
| // return U.weakCompareAndSetLongRelease(this, VALUE, expectedValue, newValue); |
| return VALUE.weakCompareAndSetRelease(this, expectedValue, newValue); |
| } |
| |
| } |
