src/java.base/share/classes/java/util/concurrent/atomic/AtomicLong.java - platform/libcore - Git at Google

 /*
  * 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.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.
      */
     private static final jdk.internal.misc.Unsafe U = jdk.internal.misc.Unsafe.getUnsafe();
     private static final long VALUE = U.objectFieldOffset(AtomicLong.class, "value");

     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
         U.putLongVolatile(this, VALUE, 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) {
         U.putLongRelease(this, VALUE, 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) {
         return U.getAndSetLong(this, VALUE, 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) {
         return U.compareAndSetLong(this, VALUE, 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) {
         return U.weakCompareAndSetLongPlain(this, VALUE, 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) {
         return U.weakCompareAndSetLongPlain(this, VALUE, 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() {
         return U.getAndAddLong(this, VALUE, 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() {
         return U.getAndAddLong(this, VALUE, -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) {
         return U.getAndAddLong(this, VALUE, 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() {
         return U.getAndAddLong(this, VALUE, 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() {
         return U.getAndAddLong(this, VALUE, -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) {
         return U.getAndAddLong(this, VALUE, 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 Conversions
      */
     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 Conversions
      */
     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 Conversions
      */
     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() {
         return U.getLong(this, VALUE);
     }

     /**
      * 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) {
         U.putLong(this, VALUE, newValue);
     }

     /**
      * Returns the current value,
      * with memory effects as specified by {@link VarHandle#getOpaque}.
      *
      * @return the value
      * @since 9
      */
     public final long getOpaque() {
         return U.getLongOpaque(this, VALUE);
     }

     /**
      * 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) {
         U.putLongOpaque(this, VALUE, newValue);
     }

     /**
      * Returns the current value,
      * with memory effects as specified by {@link VarHandle#getAcquire}.
      *
      * @return the value
      * @since 9
      */
     public final long getAcquire() {
         return U.getLongAcquire(this, VALUE);
     }

     /**
      * 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) {
         U.putLongRelease(this, VALUE, 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) {
         return U.compareAndExchangeLong(this, VALUE, 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) {
         return U.compareAndExchangeLongAcquire(this, VALUE, 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) {
         return U.compareAndExchangeLongRelease(this, VALUE, 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) {
         return U.weakCompareAndSetLong(this, VALUE, 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) {
         return U.weakCompareAndSetLongAcquire(this, VALUE, 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) {
         return U.weakCompareAndSetLongRelease(this, VALUE, expectedValue, newValue);
     }

 }
	/*
	* 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.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.
	*/
	private static final jdk.internal.misc.Unsafe U = jdk.internal.misc.Unsafe.getUnsafe();
	private static final long VALUE = U.objectFieldOffset(AtomicLong.class, "value");

	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
	U.putLongVolatile(this, VALUE, 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) {
	U.putLongRelease(this, VALUE, 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) {
	return U.getAndSetLong(this, VALUE, 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) {
	return U.compareAndSetLong(this, VALUE, 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) {
	return U.weakCompareAndSetLongPlain(this, VALUE, 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) {
	return U.weakCompareAndSetLongPlain(this, VALUE, 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() {
	return U.getAndAddLong(this, VALUE, 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() {
	return U.getAndAddLong(this, VALUE, -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) {
	return U.getAndAddLong(this, VALUE, 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() {
	return U.getAndAddLong(this, VALUE, 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() {
	return U.getAndAddLong(this, VALUE, -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) {
	return U.getAndAddLong(this, VALUE, 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 Conversions
	*/
	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 Conversions
	*/
	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 Conversions
	*/
	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() {
	return U.getLong(this, VALUE);
	}

	/**
	* 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) {
	U.putLong(this, VALUE, newValue);
	}

	/**
	* Returns the current value,
	* with memory effects as specified by {@link VarHandle#getOpaque}.
	*
	* @return the value
	* @since 9
	*/
	public final long getOpaque() {
	return U.getLongOpaque(this, VALUE);
	}

	/**
	* 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) {
	U.putLongOpaque(this, VALUE, newValue);
	}

	/**
	* Returns the current value,
	* with memory effects as specified by {@link VarHandle#getAcquire}.
	*
	* @return the value
	* @since 9
	*/
	public final long getAcquire() {
	return U.getLongAcquire(this, VALUE);
	}

	/**
	* 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) {
	U.putLongRelease(this, VALUE, 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) {
	return U.compareAndExchangeLong(this, VALUE, 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) {
	return U.compareAndExchangeLongAcquire(this, VALUE, 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) {
	return U.compareAndExchangeLongRelease(this, VALUE, 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) {
	return U.weakCompareAndSetLong(this, VALUE, 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) {
	return U.weakCompareAndSetLongAcquire(this, VALUE, 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) {
	return U.weakCompareAndSetLongRelease(this, VALUE, expectedValue, newValue);
	}

	}