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92 lines
2.8 KiB
Java
92 lines
2.8 KiB
Java
/*
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* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
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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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package java.lang.runtime;
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import java.lang.ref.ReferenceQueue;
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import java.lang.ref.SoftReference;
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import java.util.Objects;
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/**
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* {@link SoftReference} wrapper key for entries in the backing map.
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*
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* @param <T> key type
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*
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* @since 21
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*
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* Warning: This class is part of PreviewFeature.Feature.STRING_TEMPLATES.
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* Do not rely on its availability.
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*/
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final class SoftReferenceKey<T> extends SoftReference<T> implements ReferenceKey<T> {
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/**
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* Saved hashcode of the key. Used when {@link SoftReference} is
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* null.
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*/
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private final int hashcode;
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/**
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* Package-Protected constructor.
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*
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* @param key unwrapped key value
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* @param queue reference queue
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*/
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SoftReferenceKey(T key, ReferenceQueue<T> queue) {
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super(key, queue);
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this.hashcode = Objects.hashCode(key);
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}
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/**
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* Cleanup unused key. No need to enqueue since the key did not make it
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* into the map.
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*/
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@Override
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public void unused() {
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clear();
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}
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@Override
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public boolean equals(Object obj) {
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// Necessary when removing a null reference
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if (obj == this) {
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return true;
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}
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// Necessary when comparing an unwrapped key
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if (obj instanceof ReferenceKey<?> key) {
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obj = key.get();
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}
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return Objects.equals(get(), obj);
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}
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@Override
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public int hashCode() {
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// Use saved hashcode
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return hashcode;
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}
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@Override
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public String toString() {
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return this.getClass().getCanonicalName() + "#" + System.identityHashCode(this);
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}
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}
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