org.spf4j.recyclable.impl.Powerof2ThreadLocalRecyclingSupplier Maven / Gradle / Ivy

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/*
 * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Additionally licensed with:
 *
 * 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 org.spf4j.recyclable.impl;

import java.lang.ref.Reference;
import java.util.ArrayDeque;
import java.util.Deque;
import org.spf4j.base.IntMath;
import org.spf4j.base.ReferenceType;
import org.spf4j.recyclable.SizedRecyclingSupplier;

/**
 * recycling supplier that allows you to recycle objects.
 * Recycling objects is dangerous business, care should be used.
 * @author zoly
 */
public final class Powerof2ThreadLocalRecyclingSupplier implements SizedRecyclingSupplier {

    private final SizedRecyclingSupplier.Factory factory;

    private final ReferenceType refType;

    private final ThreadLocal> []> localObjects;

    public Powerof2ThreadLocalRecyclingSupplier(final Factory factory, final ReferenceType refType) {
        this.factory = factory;
        this.refType = refType;
        localObjects = new ThreadLocal> []>() {

            @Override
            protected  Deque>[] initialValue() {
                Deque>[] result =  new Deque[28];
                for (int i = 0; i < result.length; i++) {
                    result[i] = new ArrayDeque<>();
                }
                return result;
            }
        };
    }

    @Override
    public T get(final int size) {
        Deque>[] available = localObjects.get();
        int idx = IntMath.closestPowerOf2(size);
        Deque> refs = available[idx];
        if (refs.isEmpty()) {
            int actualSize = 1 << idx;
            return factory.create(actualSize);
        } else {
            T result;
            do {
                Reference removeLast = refs.removeLast();
                result = removeLast.get();
            } while (result == null && !refs.isEmpty());
            if (result == null) {
                int actualSize = 1 << idx;
                return factory.create(actualSize);
            } else {
                return result;
            }
        }
    }

    @Override
    public void recycle(final T object) {
        int size = factory.size(object);
        int idx = IntMath.closestPowerOf2(size);
        Deque>[] available = localObjects.get();
        Deque> refs = available[idx];
        refs.addLast(refType.create(object));
    }

    @Override
    public String toString() {
        return "Powerof2ThreadLocalRecyclingSupplier{" + "factory=" + factory + ", refType=" + refType + '}';
    }

}