current/sdk/sdk_library/public/art.module.public.api_stub_sources/java/util/concurrent/atomic/DoubleAccumulator.java

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 *
 * 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
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/*
 * 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;


/**
 * One or more variables that together maintain a running {@code double}
 * value updated using a supplied function.  When updates (method
 * {@link #accumulate}) are contended across threads, the set of variables
 * may grow dynamically to reduce contention.  Method {@link #get}
 * (or, equivalently, {@link #doubleValue}) returns the current value
 * across the variables maintaining updates.
 *
 * <p>This class is usually preferable to alternatives when multiple
 * threads update a common value that is used for purposes such as
 * summary statistics that are frequently updated but less frequently
 * read.
 *
 * <p>The supplied accumulator 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.  For example, to maintain a running maximum value, you
 * could supply {@code Double::max} along with {@code
 * Double.NEGATIVE_INFINITY} as the identity. The order of
 * accumulation within or across threads is not guaranteed. Thus, this
 * class may not be applicable if numerical stability is required,
 * especially when combining values of substantially different orders
 * of magnitude.
 *
 * <p>Class {@link java.util.concurrent.atomic.DoubleAdder DoubleAdder} provides analogs of the functionality
 * of this class for the common special case of maintaining sums.  The
 * call {@code new DoubleAdder()} is equivalent to {@code new
 * DoubleAccumulator((x, y) -> x + y, 0.0)}.
 *
 * <p>This class extends {@link java.lang.Number Number}, but does <em>not</em> define
 * methods such as {@code equals}, {@code hashCode} and {@code
 * compareTo} because instances are expected to be mutated, and so are
 * not useful as collection keys.
 *
 * @since 1.8
 * @author Doug Lea
 */

@SuppressWarnings({"unchecked", "deprecation", "all"})
public class DoubleAccumulator extends java.lang.Number implements java.io.Serializable {

/**
 * Creates a new instance using the given accumulator function
 * and identity element.
 * @param accumulatorFunction a side-effect-free function of two arguments
 * @param identity identity (initial value) for the accumulator function
 */

public DoubleAccumulator(java.util.function.DoubleBinaryOperator accumulatorFunction, double identity) { throw new RuntimeException("Stub!"); }

/**
 * Updates with the given value.
 *
 * @param x the value
 */

public void accumulate(double x) { throw new RuntimeException("Stub!"); }

/**
 * Returns the current value.  The returned value is <em>NOT</em>
 * an atomic snapshot; invocation in the absence of concurrent
 * updates returns an accurate result, but concurrent updates that
 * occur while the value is being calculated might not be
 * incorporated.
 *
 * @return the current value
 */

public double get() { throw new RuntimeException("Stub!"); }

/**
 * Resets variables maintaining updates to the identity value.
 * This method may be a useful alternative to creating a new
 * updater, but is only effective if there are no concurrent
 * updates.  Because this method is intrinsically racy, it should
 * only be used when it is known that no threads are concurrently
 * updating.
 */

public void reset() { throw new RuntimeException("Stub!"); }

/**
 * Equivalent in effect to {@link #get} followed by {@link
 * #reset}. This method may apply for example during quiescent
 * points between multithreaded computations.  If there are
 * updates concurrent with this method, the returned value is
 * <em>not</em> guaranteed to be the final value occurring before
 * the reset.
 *
 * @return the value before reset
 */

public double getThenReset() { throw new RuntimeException("Stub!"); }

/**
 * Returns the String representation of the current value.
 * @return the String representation of the current value
 */

public java.lang.String toString() { throw new RuntimeException("Stub!"); }

/**
 * Equivalent to {@link #get}.
 *
 * @return the current value
 */

public double doubleValue() { throw new RuntimeException("Stub!"); }

/**
 * Returns the {@linkplain #get current value} as a {@code long}
 * after a narrowing primitive conversion.
 */

public long longValue() { throw new RuntimeException("Stub!"); }

/**
 * Returns the {@linkplain #get current value} as an {@code int}
 * after a narrowing primitive conversion.
 */

public int intValue() { throw new RuntimeException("Stub!"); }

/**
 * Returns the {@linkplain #get current value} as a {@code float}
 * after a narrowing primitive conversion.
 */

public float floatValue() { throw new RuntimeException("Stub!"); }
}