core/src/com/google/inject/internal/util/FinalizableSoftReference.java

/*
 * Copyright (C) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject.internal.util;

import java.lang.ref.SoftReference;

/**
 * Soft reference with a {@code finalizeReferent()} method which a background
 * thread invokes after the garbage collector reclaims the referent. This is a
 * simpler alternative to using a {@link java.lang.ref.ReferenceQueue}.
 *
 * @author Bob Lee
 */
public abstract class FinalizableSoftReference<T> extends SoftReference<T>
    implements FinalizableReference {

  /**
   * Consructs a new finalizable soft reference.
   *
   * @param referent to softly reference
   * @param queue that should finalize the referent
   */
  protected FinalizableSoftReference(T referent,
      FinalizableReferenceQueue queue) {
    super(referent, queue.queue);
    queue.cleanUp();
  }
}