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This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * Copyright (c) 2013, 2017 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.json;

import org.glassfish.json.api.BufferPool;

import java.lang.ref.WeakReference;
import java.util.concurrent.ConcurrentLinkedQueue;

/**
 * char[] pool that pool instances of char[] which are expensive to create.
 *
 * @author Jitendra Kotamraju
 */
class BufferPoolImpl implements BufferPool {

    // volatile since multiple threads may access queue reference
    private volatile WeakReference> queue;

    /**
     * Gets a new object from the pool.
     *
     * 
     * If no object is available in the pool, this method creates a new one.
     *
     * @return
     *      always non-null.
     */
    @Override
    public final char[] take() {
        char[] t = getQueue().poll();
        if (t==null)
            return new char[4096];
        return t;
    }

    private ConcurrentLinkedQueue getQueue() {
        WeakReference> q = queue;
        if (q != null) {
            ConcurrentLinkedQueue d = q.get();
            if (d != null)
                return d;
        }

        // overwrite the queue
        ConcurrentLinkedQueue d = new ConcurrentLinkedQueue<>();
        queue = new WeakReference<>(d);

        return d;
    }

    /**
     * Returns an object back to the pool.
     */
    @Override
    public final void recycle(char[] t) {
        getQueue().offer(t);
    }

}