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8187443: Forest Consolidation: Move files to unified layout
Reviewed-by: darcy, ihse
This commit is contained in:
Erik Joelsson
parent
270fe13182
commit
3789983e89
56923 changed files with 3 additions and 15727 deletions
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@ -0,0 +1,447 @@
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/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* This file is available under and governed by the GNU General Public
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* License version 2 only, as published by the Free Software Foundation.
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* However, the following notice accompanied the original version of this
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* file:
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*
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* Written by Doug Lea with assistance from members of JCP JSR-166
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* Expert Group and released to the public domain, as explained at
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* http://creativecommons.org/publicdomain/zero/1.0/
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*/
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package java.util.concurrent;
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import java.util.AbstractSet;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.Objects;
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import java.util.Set;
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import java.util.Spliterator;
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import java.util.Spliterators;
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import java.util.function.Consumer;
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import java.util.function.Predicate;
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/**
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* A {@link Set} that uses an internal {@link CopyOnWriteArrayList}
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* for all of its operations. Thus, it shares the same basic properties:
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* <ul>
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* <li>It is best suited for applications in which set sizes generally
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* stay small, read-only operations
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* vastly outnumber mutative operations, and you need
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* to prevent interference among threads during traversal.
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* <li>It is thread-safe.
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* <li>Mutative operations ({@code add}, {@code set}, {@code remove}, etc.)
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* are expensive since they usually entail copying the entire underlying
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* array.
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* <li>Iterators do not support the mutative {@code remove} operation.
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* <li>Traversal via iterators is fast and cannot encounter
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* interference from other threads. Iterators rely on
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* unchanging snapshots of the array at the time the iterators were
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* constructed.
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* </ul>
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*
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* <p><b>Sample Usage.</b> The following code sketch uses a
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* copy-on-write set to maintain a set of Handler objects that
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* perform some action upon state updates.
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*
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* <pre> {@code
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* class Handler { void handle(); ... }
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*
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* class X {
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* private final CopyOnWriteArraySet<Handler> handlers
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* = new CopyOnWriteArraySet<>();
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* public void addHandler(Handler h) { handlers.add(h); }
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*
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* private long internalState;
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* private synchronized void changeState() { internalState = ...; }
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*
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* public void update() {
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* changeState();
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* for (Handler handler : handlers)
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* handler.handle();
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* }
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* }}</pre>
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*
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* <p>This class is a member of the
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* <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
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* Java Collections Framework</a>.
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*
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* @see CopyOnWriteArrayList
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* @since 1.5
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* @author Doug Lea
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* @param <E> the type of elements held in this set
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*/
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public class CopyOnWriteArraySet<E> extends AbstractSet<E>
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implements java.io.Serializable {
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private static final long serialVersionUID = 5457747651344034263L;
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private final CopyOnWriteArrayList<E> al;
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/**
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* Creates an empty set.
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*/
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public CopyOnWriteArraySet() {
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al = new CopyOnWriteArrayList<E>();
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}
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/**
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* Creates a set containing all of the elements of the specified
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* collection.
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*
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* @param c the collection of elements to initially contain
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* @throws NullPointerException if the specified collection is null
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*/
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public CopyOnWriteArraySet(Collection<? extends E> c) {
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if (c.getClass() == CopyOnWriteArraySet.class) {
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@SuppressWarnings("unchecked") CopyOnWriteArraySet<E> cc =
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(CopyOnWriteArraySet<E>)c;
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al = new CopyOnWriteArrayList<E>(cc.al);
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}
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else {
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al = new CopyOnWriteArrayList<E>();
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al.addAllAbsent(c);
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}
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}
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/**
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* Returns the number of elements in this set.
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*
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* @return the number of elements in this set
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*/
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public int size() {
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return al.size();
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}
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/**
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* Returns {@code true} if this set contains no elements.
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*
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* @return {@code true} if this set contains no elements
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*/
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public boolean isEmpty() {
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return al.isEmpty();
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}
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/**
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* Returns {@code true} if this set contains the specified element.
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* More formally, returns {@code true} if and only if this set
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* contains an element {@code e} such that {@code Objects.equals(o, e)}.
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*
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* @param o element whose presence in this set is to be tested
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* @return {@code true} if this set contains the specified element
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*/
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public boolean contains(Object o) {
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return al.contains(o);
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}
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/**
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* Returns an array containing all of the elements in this set.
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* If this set makes any guarantees as to what order its elements
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* are returned by its iterator, this method must return the
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* elements in the same order.
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*
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* <p>The returned array will be "safe" in that no references to it
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* are maintained by this set. (In other words, this method must
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* allocate a new array even if this set is backed by an array).
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* The caller is thus free to modify the returned array.
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*
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* <p>This method acts as bridge between array-based and collection-based
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* APIs.
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*
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* @return an array containing all the elements in this set
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*/
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public Object[] toArray() {
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return al.toArray();
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}
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/**
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* Returns an array containing all of the elements in this set; the
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* runtime type of the returned array is that of the specified array.
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* If the set fits in the specified array, it is returned therein.
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* Otherwise, a new array is allocated with the runtime type of the
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* specified array and the size of this set.
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*
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* <p>If this set fits in the specified array with room to spare
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* (i.e., the array has more elements than this set), the element in
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* the array immediately following the end of the set is set to
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* {@code null}. (This is useful in determining the length of this
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* set <i>only</i> if the caller knows that this set does not contain
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* any null elements.)
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*
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* <p>If this set makes any guarantees as to what order its elements
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* are returned by its iterator, this method must return the elements
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* in the same order.
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*
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* <p>Like the {@link #toArray()} method, this method acts as bridge between
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* array-based and collection-based APIs. Further, this method allows
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* precise control over the runtime type of the output array, and may,
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* under certain circumstances, be used to save allocation costs.
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*
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* <p>Suppose {@code x} is a set known to contain only strings.
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* The following code can be used to dump the set into a newly allocated
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* array of {@code String}:
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*
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* <pre> {@code String[] y = x.toArray(new String[0]);}</pre>
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*
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* Note that {@code toArray(new Object[0])} is identical in function to
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* {@code toArray()}.
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*
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* @param a the array into which the elements of this set are to be
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* stored, if it is big enough; otherwise, a new array of the same
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* runtime type is allocated for this purpose.
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* @return an array containing all the elements in this set
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* @throws ArrayStoreException if the runtime type of the specified array
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* is not a supertype of the runtime type of every element in this
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* set
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* @throws NullPointerException if the specified array is null
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*/
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public <T> T[] toArray(T[] a) {
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return al.toArray(a);
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}
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/**
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* Removes all of the elements from this set.
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* The set will be empty after this call returns.
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*/
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public void clear() {
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al.clear();
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}
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/**
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* Removes the specified element from this set if it is present.
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* More formally, removes an element {@code e} such that
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* {@code Objects.equals(o, e)}, if this set contains such an element.
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* Returns {@code true} if this set contained the element (or
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* equivalently, if this set changed as a result of the call).
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* (This set will not contain the element once the call returns.)
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*
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* @param o object to be removed from this set, if present
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* @return {@code true} if this set contained the specified element
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*/
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public boolean remove(Object o) {
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return al.remove(o);
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}
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/**
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* Adds the specified element to this set if it is not already present.
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* More formally, adds the specified element {@code e} to this set if
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* the set contains no element {@code e2} such that
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* {@code Objects.equals(e, e2)}.
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* If this set already contains the element, the call leaves the set
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* unchanged and returns {@code false}.
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*
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* @param e element to be added to this set
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* @return {@code true} if this set did not already contain the specified
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* element
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*/
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public boolean add(E e) {
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return al.addIfAbsent(e);
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}
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/**
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* Returns {@code true} if this set contains all of the elements of the
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* specified collection. If the specified collection is also a set, this
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* method returns {@code true} if it is a <i>subset</i> of this set.
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*
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* @param c collection to be checked for containment in this set
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* @return {@code true} if this set contains all of the elements of the
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* specified collection
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* @throws NullPointerException if the specified collection is null
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* @see #contains(Object)
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*/
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public boolean containsAll(Collection<?> c) {
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return (c instanceof Set)
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? compareSets(al.getArray(), (Set<?>) c) >= 0
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: al.containsAll(c);
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}
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/**
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* Tells whether the objects in snapshot (regarded as a set) are a
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* superset of the given set.
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*
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* @return -1 if snapshot is not a superset, 0 if the two sets
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* contain precisely the same elements, and 1 if snapshot is a
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* proper superset of the given set
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*/
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private static int compareSets(Object[] snapshot, Set<?> set) {
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// Uses O(n^2) algorithm, that is only appropriate for small
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// sets, which CopyOnWriteArraySets should be.
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//
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// Optimize up to O(n) if the two sets share a long common prefix,
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// as might happen if one set was created as a copy of the other set.
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final int len = snapshot.length;
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// Mark matched elements to avoid re-checking
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final boolean[] matched = new boolean[len];
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// j is the largest int with matched[i] true for { i | 0 <= i < j }
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int j = 0;
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outer: for (Object x : set) {
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for (int i = j; i < len; i++) {
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if (!matched[i] && Objects.equals(x, snapshot[i])) {
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matched[i] = true;
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if (i == j)
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do { j++; } while (j < len && matched[j]);
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continue outer;
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}
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}
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return -1;
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}
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return (j == len) ? 0 : 1;
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}
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/**
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* Adds all of the elements in the specified collection to this set if
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* they're not already present. If the specified collection is also a
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* set, the {@code addAll} operation effectively modifies this set so
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* that its value is the <i>union</i> of the two sets. The behavior of
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* this operation is undefined if the specified collection is modified
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* while the operation is in progress.
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*
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* @param c collection containing elements to be added to this set
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* @return {@code true} if this set changed as a result of the call
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* @throws NullPointerException if the specified collection is null
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* @see #add(Object)
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*/
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public boolean addAll(Collection<? extends E> c) {
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return al.addAllAbsent(c) > 0;
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}
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/**
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* Removes from this set all of its elements that are contained in the
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* specified collection. If the specified collection is also a set,
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* this operation effectively modifies this set so that its value is the
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* <i>asymmetric set difference</i> of the two sets.
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*
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* @param c collection containing elements to be removed from this set
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* @return {@code true} if this set changed as a result of the call
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* @throws ClassCastException if the class of an element of this set
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* is incompatible with the specified collection
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* (<a href="{@docRoot}/java/util/Collection.html#optional-restrictions">optional</a>)
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* @throws NullPointerException if this set contains a null element and the
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* specified collection does not permit null elements
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* (<a href="{@docRoot}/java/util/Collection.html#optional-restrictions">optional</a>),
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* or if the specified collection is null
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* @see #remove(Object)
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*/
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public boolean removeAll(Collection<?> c) {
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return al.removeAll(c);
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}
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/**
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* Retains only the elements in this set that are contained in the
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* specified collection. In other words, removes from this set all of
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* its elements that are not contained in the specified collection. If
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* the specified collection is also a set, this operation effectively
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* modifies this set so that its value is the <i>intersection</i> of the
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* two sets.
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*
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* @param c collection containing elements to be retained in this set
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* @return {@code true} if this set changed as a result of the call
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* @throws ClassCastException if the class of an element of this set
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* is incompatible with the specified collection
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* (<a href="{@docRoot}/java/util/Collection.html#optional-restrictions">optional</a>)
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* @throws NullPointerException if this set contains a null element and the
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* specified collection does not permit null elements
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* (<a href="{@docRoot}/java/util/Collection.html#optional-restrictions">optional</a>),
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* or if the specified collection is null
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* @see #remove(Object)
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*/
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public boolean retainAll(Collection<?> c) {
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return al.retainAll(c);
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}
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/**
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* Returns an iterator over the elements contained in this set
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* in the order in which these elements were added.
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*
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* <p>The returned iterator provides a snapshot of the state of the set
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* when the iterator was constructed. No synchronization is needed while
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* traversing the iterator. The iterator does <em>NOT</em> support the
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* {@code remove} method.
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*
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* @return an iterator over the elements in this set
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*/
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public Iterator<E> iterator() {
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return al.iterator();
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}
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/**
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* Compares the specified object with this set for equality.
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* Returns {@code true} if the specified object is the same object
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* as this object, or if it is also a {@link Set} and the elements
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* returned by an {@linkplain Set#iterator() iterator} over the
|
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* specified set are the same as the elements returned by an
|
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* iterator over this set. More formally, the two iterators are
|
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* considered to return the same elements if they return the same
|
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* number of elements and for every element {@code e1} returned by
|
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* the iterator over the specified set, there is an element
|
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* {@code e2} returned by the iterator over this set such that
|
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* {@code Objects.equals(e1, e2)}.
|
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*
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||||
* @param o object to be compared for equality with this set
|
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* @return {@code true} if the specified object is equal to this set
|
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*/
|
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public boolean equals(Object o) {
|
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return (o == this)
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|| ((o instanceof Set)
|
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&& compareSets(al.getArray(), (Set<?>) o) == 0);
|
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}
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|
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/**
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* @throws NullPointerException {@inheritDoc}
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*/
|
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public boolean removeIf(Predicate<? super E> filter) {
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return al.removeIf(filter);
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}
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/**
|
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* @throws NullPointerException {@inheritDoc}
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*/
|
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public void forEach(Consumer<? super E> action) {
|
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al.forEach(action);
|
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}
|
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|
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/**
|
||||
* Returns a {@link Spliterator} over the elements in this set in the order
|
||||
* in which these elements were added.
|
||||
*
|
||||
* <p>The {@code Spliterator} reports {@link Spliterator#IMMUTABLE},
|
||||
* {@link Spliterator#DISTINCT}, {@link Spliterator#SIZED}, and
|
||||
* {@link Spliterator#SUBSIZED}.
|
||||
*
|
||||
* <p>The spliterator provides a snapshot of the state of the set
|
||||
* when the spliterator was constructed. No synchronization is needed while
|
||||
* operating on the spliterator.
|
||||
*
|
||||
* @return a {@code Spliterator} over the elements in this set
|
||||
* @since 1.8
|
||||
*/
|
||||
public Spliterator<E> spliterator() {
|
||||
return Spliterators.spliterator
|
||||
(al.getArray(), Spliterator.IMMUTABLE | Spliterator.DISTINCT);
|
||||
}
|
||||
}
|
||||
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