src/java.base/share/classes/java/lang/ref/FinalReference.java - master - niceSOFT/openjdk21

src/java.base/share/classes/java/lang/ref/FinalReference.java

57 строк2 KB

Joe Darcy

8283415: Update java.lang.ref to use sealed classes

21 мар 2022, 19:57

21 мар 2022, 19:5714b9e80

/*
 * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.lang.ref;

/**
 * Final references, used to implement finalization
 */
sealed class FinalReference<T> extends Reference<T> permits Finalizer {

    public FinalReference(T referent, ReferenceQueue<? super T> q) {
        super(referent, q);
    }

    /* May only be called when the reference is inactive, so no longer weak. */
    @Override
    public T get() {
        // Cannot call super.get() when active, as the GC could
        // deactivate immediately after the test.
        return getFromInactiveFinalReference();
    }

    /* May only be called when the reference is inactive, so no longer weak.
     * Clearing while active would discard the finalization request.
     */
    @Override
    public void clear() {
        clearInactiveFinalReference();
    }

    @Override
    public boolean enqueue() {
        throw new InternalError("should never reach here");
    }
}