com/android/server/location/contexthub/ConcurrentLinkedEvictingDeque.java

/*
 * Copyright (C) 2020 The Android Open Source Project
 *
 * 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.android.server.location.contexthub;

import java.util.concurrent.ConcurrentLinkedDeque;

/**
 * Helper class to make a ConcurrentLinkedDeque fixed-size, evicting old entries when full.
 *
 * @param <E> The type of elements held in this queue.
 */
public class ConcurrentLinkedEvictingDeque<E> extends ConcurrentLinkedDeque<E> {
    private int mSize;

    ConcurrentLinkedEvictingDeque(int size) {
        mSize = size;
    }

    @Override
    public boolean add(E elem) {
        synchronized (this) {
            if (size() == mSize) {
                poll();
            }

            return super.add(elem);
        }
    }
}