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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2012 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */
package org.glassfish.grizzly.nio;

import java.lang.ref.SoftReference;
import java.nio.ByteBuffer;
import org.glassfish.grizzly.ThreadCache;

/**
 * Thread-local Direct {@link ByteBuffer} storage.
 * 
 * @author Alexey Stashok
 */
public final class DirectByteBufferRecord {
    ByteBuffer strongRef;
    private SoftReference softRef;

    private static final ThreadCache.CachedTypeIndex CACHE_IDX =
            ThreadCache.obtainIndex("direct-buffer-cache", DirectByteBufferRecord.class, 1);
    
    public static DirectByteBufferRecord allocate(final int size) {
        DirectByteBufferRecord record = ThreadCache.getFromCache(CACHE_IDX);
        final ByteBuffer byteBuffer;
        if (record != null) {
            if ((byteBuffer = record.switchToStrong()) != null) {
                if (byteBuffer.remaining() >= size) {
                    return record;
                }
            }
        } else {
            record = new DirectByteBufferRecord();
            ThreadCache.putToCache(CACHE_IDX, record);
        }

        record.reset(ByteBuffer.allocateDirect(size));
        return record;
    }

    public ByteBuffer getByteBuffer() {
        return strongRef;
    }
    
    void reset(final ByteBuffer byteBuffer) {
        strongRef = byteBuffer;
        softRef = null;
    }

    ByteBuffer switchToStrong() {
        if (strongRef == null && softRef != null) {
            strongRef = softRef.get();
        }
        return strongRef;
    }

    void switchToSoft() {
        if (strongRef != null && softRef == null) {
            softRef = new SoftReference(strongRef);
        }
        strongRef = null;
    }
    
    public void release() {
        strongRef.clear();
        switchToSoft();
//        ThreadCache.putToCache(CACHE_IDX, directByteBufferRecord);
    }
}