ojluni/src/main/java/java/util/concurrent/atomic/AtomicLong.java - platform/libcore.git - 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 sun.misc.Unsafe;

 /**
  * A {@code long} value that may be updated atomically.  See the
  * {@link java.util.concurrent.atomic} package specification for
  * description of the properties of atomic variables. 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;

     // setup to use Unsafe.compareAndSwapLong for updates
     private static final Unsafe unsafe = Unsafe.getUnsafe();
     private static final long valueOffset;

     /**
      * Records whether the underlying JVM supports lockless
      * compareAndSwap for longs. While the Unsafe.compareAndSwapLong
      * 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();

     static {
       try {
         valueOffset = unsafe.objectFieldOffset
             (AtomicLong.class.getDeclaredField("value"));
       } catch (Exception ex) { throw new Error(ex); }
     }

     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() {
     }

     /**
      * Gets the current value.
      *
      * @return the current value
      */
     public final long get() {
         return value;
     }

     /**
      * Sets to the given value.
      *
      * @param newValue the new value
      */
     public final void set(long newValue) {
         value = newValue;
     }

     /**
      * Eventually sets to the given value.
      *
      * @param newValue the new value
      * @since 1.6
      */
     public final void lazySet(long newValue) {
         unsafe.putOrderedLong(this, valueOffset, newValue);
     }

     /**
      * Atomically sets to the given value and returns the old value.
      *
      * @param newValue the new value
      * @return the previous value
      */
     public final long getAndSet(long newValue) {
         while (true) {
             long current = get();
             if (compareAndSet(current, newValue))
                 return current;
         }
     }

     /**
      * Atomically sets the value to the given updated value
      * if the current value {@code ==} the expected value.
      *
      * @param expect the expected value
      * @param update the new value
      * @return true if successful. False return indicates that
      * the actual value was not equal to the expected value.
      */
     public final boolean compareAndSet(long expect, long update) {
         return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
     }

     /**
      * Atomically sets the value to the given updated value
      * if the current value {@code ==} the expected value.
      *
      * <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
      * and does not provide ordering guarantees, so is only rarely an
      * appropriate alternative to {@code compareAndSet}.
      *
      * @param expect the expected value
      * @param update the new value
      * @return true if successful.
      */
     public final boolean weakCompareAndSet(long expect, long update) {
         return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
     }

     /**
      * Atomically increments by one the current value.
      *
      * @return the previous value
      */
     public final long getAndIncrement() {
         while (true) {
             long current = get();
             long next = current + 1;
             if (compareAndSet(current, next))
                 return current;
         }
     }

     /**
      * Atomically decrements by one the current value.
      *
      * @return the previous value
      */
     public final long getAndDecrement() {
         while (true) {
             long current = get();
             long next = current - 1;
             if (compareAndSet(current, next))
                 return current;
         }
     }

     /**
      * Atomically adds the given value to the current value.
      *
      * @param delta the value to add
      * @return the previous value
      */
     public final long getAndAdd(long delta) {
         while (true) {
             long current = get();
             long next = current + delta;
             if (compareAndSet(current, next))
                 return current;
         }
     }

     /**
      * Atomically increments by one the current value.
      *
      * @return the updated value
      */
     public final long incrementAndGet() {
         for (;;) {
             long current = get();
             long next = current + 1;
             if (compareAndSet(current, next))
                 return next;
         }
     }

     /**
      * Atomically decrements by one the current value.
      *
      * @return the updated value
      */
     public final long decrementAndGet() {
         for (;;) {
             long current = get();
             long next = current - 1;
             if (compareAndSet(current, next))
                 return next;
         }
     }

     /**
      * Atomically adds the given value to the current value.
      *
      * @param delta the value to add
      * @return the updated value
      */
     public final long addAndGet(long delta) {
         for (;;) {
             long current = get();
             long next = current + delta;
             if (compareAndSet(current, next))
                 return next;
         }
     }

     /**
      * Returns the String representation of the current value.
      * @return the String representation of the current value.
      */
     public String toString() {
         return Long.toString(get());
     }


     public int intValue() {
         return (int)get();
     }

     public long longValue() {
         return get();
     }

     public float floatValue() {
         return (float)get();
     }

     public double doubleValue() {
         return (double)get();
     }

 }
	/*
	* 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 sun.misc.Unsafe;

	/**
	* A {@code long} value that may be updated atomically. See the
	* {@link java.util.concurrent.atomic} package specification for
	* description of the properties of atomic variables. 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;

	// setup to use Unsafe.compareAndSwapLong for updates
	private static final Unsafe unsafe = Unsafe.getUnsafe();
	private static final long valueOffset;

	/**
	* Records whether the underlying JVM supports lockless
	* compareAndSwap for longs. While the Unsafe.compareAndSwapLong
	* 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();

	static {
	try {
	valueOffset = unsafe.objectFieldOffset
	(AtomicLong.class.getDeclaredField("value"));
	} catch (Exception ex) { throw new Error(ex); }
	}

	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() {
	}

	/**
	* Gets the current value.
	*
	* @return the current value
	*/
	public final long get() {
	return value;
	}

	/**
	* Sets to the given value.
	*
	* @param newValue the new value
	*/
	public final void set(long newValue) {
	value = newValue;
	}

	/**
	* Eventually sets to the given value.
	*
	* @param newValue the new value
	* @since 1.6
	*/
	public final void lazySet(long newValue) {
	unsafe.putOrderedLong(this, valueOffset, newValue);
	}

	/**
	* Atomically sets to the given value and returns the old value.
	*
	* @param newValue the new value
	* @return the previous value
	*/
	public final long getAndSet(long newValue) {
	while (true) {
	long current = get();
	if (compareAndSet(current, newValue))
	return current;
	}
	}

	/**
	* Atomically sets the value to the given updated value
	* if the current value {@code ==} the expected value.
	*
	* @param expect the expected value
	* @param update the new value
	* @return true if successful. False return indicates that
	* the actual value was not equal to the expected value.
	*/
	public final boolean compareAndSet(long expect, long update) {
	return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
	}

	/**
	* Atomically sets the value to the given updated value
	* if the current value {@code ==} the expected value.
	*
	* <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
	* and does not provide ordering guarantees, so is only rarely an
	* appropriate alternative to {@code compareAndSet}.
	*
	* @param expect the expected value
	* @param update the new value
	* @return true if successful.
	*/
	public final boolean weakCompareAndSet(long expect, long update) {
	return unsafe.compareAndSwapLong(this, valueOffset, expect, update);
	}

	/**
	* Atomically increments by one the current value.
	*
	* @return the previous value
	*/
	public final long getAndIncrement() {
	while (true) {
	long current = get();
	long next = current + 1;
	if (compareAndSet(current, next))
	return current;
	}
	}

	/**
	* Atomically decrements by one the current value.
	*
	* @return the previous value
	*/
	public final long getAndDecrement() {
	while (true) {
	long current = get();
	long next = current - 1;
	if (compareAndSet(current, next))
	return current;
	}
	}

	/**
	* Atomically adds the given value to the current value.
	*
	* @param delta the value to add
	* @return the previous value
	*/
	public final long getAndAdd(long delta) {
	while (true) {
	long current = get();
	long next = current + delta;
	if (compareAndSet(current, next))
	return current;
	}
	}

	/**
	* Atomically increments by one the current value.
	*
	* @return the updated value
	*/
	public final long incrementAndGet() {
	for (;;) {
	long current = get();
	long next = current + 1;
	if (compareAndSet(current, next))
	return next;
	}
	}

	/**
	* Atomically decrements by one the current value.
	*
	* @return the updated value
	*/
	public final long decrementAndGet() {
	for (;;) {
	long current = get();
	long next = current - 1;
	if (compareAndSet(current, next))
	return next;
	}
	}

	/**
	* Atomically adds the given value to the current value.
	*
	* @param delta the value to add
	* @return the updated value
	*/
	public final long addAndGet(long delta) {
	for (;;) {
	long current = get();
	long next = current + delta;
	if (compareAndSet(current, next))
	return next;
	}
	}

	/**
	* Returns the String representation of the current value.
	* @return the String representation of the current value.
	*/
	public String toString() {
	return Long.toString(get());
	}


	public int intValue() {
	return (int)get();
	}

	public long longValue() {
	return get();
	}

	public float floatValue() {
	return (float)get();
	}

	public double doubleValue() {
	return (double)get();
	}

	}