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*/ |
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package jsr166e; |
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import java.util.concurrent.atomic.AtomicLong; |
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> |
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import java.io.IOException; |
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– |
import java.io.Serializable; |
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import java.io.ObjectInputStream; |
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import java.io.ObjectOutputStream; |
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import java.io.Serializable; |
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import java.util.concurrent.atomic.AtomicLong; |
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/** |
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* One or more variables that together maintain an initially zero |
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* #longValue}) returns the current total combined across the |
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* variables maintaining the sum. |
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* |
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* <p> This class is usually preferable to {@link AtomicLong} when |
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* <p>This class is usually preferable to {@link AtomicLong} when |
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* multiple threads update a common sum that is used for purposes such |
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* as collecting statistics, not for fine-grained synchronization |
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* control. Under low update contention, the two classes have similar |
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* consumption. |
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* |
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* <p>This class extends {@link Number}, but does <em>not</em> define |
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* methods such as {@code hashCode} and {@code compareTo} because |
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* instances are expected to be mutated, and so are not useful as |
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* collection keys. |
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* methods such as {@code equals}, {@code hashCode} and {@code |
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* compareTo} because instances are expected to be mutated, and so are |
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* not useful as collection keys. |
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* |
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* <p><em>jsr166e note: This class is targeted to be placed in |
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* java.util.concurrent.atomic<em> |
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* java.util.concurrent.atomic.</em> |
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* |
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* @since 1.8 |
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* @author Doug Lea |
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*/ |
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public class LongAdder extends Striped64 implements Serializable { |
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* @param x the value to add |
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*/ |
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public void add(long x) { |
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Cell[] as; long b, v; HashCode hc; Cell a; int n; |
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Cell[] as; long b, v; int[] hc; Cell a; int n; |
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if ((as = cells) != null || !casBase(b = base, b + x)) { |
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boolean uncontended = true; |
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int h = (hc = threadHashCode.get()).code; |
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if (as == null || (n = as.length) < 1 || |
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(a = as[(n - 1) & h]) == null || |
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if ((hc = threadHashCode.get()) == null || |
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as == null || (n = as.length) < 1 || |
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(a = as[(n - 1) & hc[0]]) == null || |
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!(uncontended = a.cas(v = a.value, v + x))) |
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retryUpdate(x, hc, uncontended); |
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} |
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/** |
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* Returns the current sum. The returned value is <em>NOT</em> an |
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* atomic snapshot: Invocation in the absence of concurrent |
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* atomic snapshot; invocation in the absence of concurrent |
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* updates returns an accurate result, but concurrent updates that |
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* occur while the sum is being calculated might not be |
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* incorporated. |
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|
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/** |
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* Returns the String representation of the {@link #sum}. |
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* @return the String representation of the {@link #sum}. |
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* @return the String representation of the {@link #sum} |
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*/ |
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public String toString() { |
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return Long.toString(sum()); |
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return (double)sum(); |
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} |
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private void writeObject(java.io.ObjectOutputStream s) |
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throws java.io.IOException { |
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> |
private void writeObject(ObjectOutputStream s) throws IOException { |
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s.defaultWriteObject(); |
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s.writeLong(sum()); |
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} |
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private void readObject(ObjectInputStream s) |
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throws IOException, ClassNotFoundException { |
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throws IOException, ClassNotFoundException { |
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s.defaultReadObject(); |
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busy = 0; |
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cells = null; |
