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Coroutines, continuations, fibers, actors and message passing for the JVM

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// Copyright 2014 nilangshah - offered under the terms of the MIT License

package kilim.concurrent;

import static kilim.concurrent.UnsafeAccess.UNSAFE;

abstract class VolatileReferenceCellValue extends VolatileLongCellPrePad {
	protected volatile V value;
}

@SuppressWarnings("restriction")
public class VolatileReferenceCell extends VolatileReferenceCellValue {
	volatile long p10, p11, p12, p13, p14, p15, p16;
	private static final long valueOffset;

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

	public VolatileReferenceCell(V initialValue) {
		value = initialValue;
	}

	public VolatileReferenceCell() {
	}

	public final V get() {
		return value;
	}

	public final void set(V newValue) {
		value = newValue;
	}

	public final void lazySet(V newValue) {
		UNSAFE.putOrderedObject(this, valueOffset, newValue);
	}

	public final boolean compareAndSet(V expect, V update) {
		return UNSAFE.compareAndSwapObject(this, valueOffset, expect, update);
	}

	public final boolean weakCompareAndSet(V expect, V update) {
		return UNSAFE.compareAndSwapObject(this, valueOffset, expect, update);
	}

	public final V getAndSet(V newValue) {
		while (true) {
			V x = get();
			if (compareAndSet(x, newValue))
				return x;
		}
	}

	public String toString() {
		return String.valueOf(get());
	}

}