/*

 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.xml.internal.stream.util;

import java.lang.ref.*;

/**

 * Buffer allocator for buffers of sizes 128 B, 2 KB and 8 KB. Includes

 * methods for allocating and freeing buffers.

 *

 * @author Binu John

 * @author Santiago PericasGeertsen

 */

public class BufferAllocator {

    private static final int SMALL_SIZE_LIMIT = 128;

    private static final int MEDIUM_SIZE_LIMIT = 2048;

    private static final int LARGE_SIZE_LIMIT = 8192;

    char[] smallCharBuffer;

    char[] mediumCharBuffer;

    char[] largeCharBuffer;

    byte[] smallByteBuffer;

    byte[] mediumByteBuffer;

    byte[] largeByteBuffer;

    public BufferAllocator() {

    }

    public char[] getCharBuffer(int size) {

        if (size <= SMALL_SIZE_LIMIT) {

            char[] buffer = smallCharBuffer;

            smallCharBuffer = null;

            return buffer;

        }

        else if (size <= MEDIUM_SIZE_LIMIT) {

            char[] buffer = mediumCharBuffer;

            mediumCharBuffer = null;

            return buffer;

        }

        else if (size <= LARGE_SIZE_LIMIT) {

            char[] buffer = largeCharBuffer;

            largeCharBuffer = null;

            return buffer;

        }

        return null;

    }

    public void returnCharBuffer(char[] c) {

        if (c == null) {

            return;

        }

        if (c.length <= SMALL_SIZE_LIMIT) {

            smallCharBuffer = c;

        }

        else if (c.length <= MEDIUM_SIZE_LIMIT) {

            mediumCharBuffer = c;

        }

        else if (c.length <= LARGE_SIZE_LIMIT) {

            largeCharBuffer = c;

        }

    }

    public byte[] getByteBuffer(int size) {

        if (size <= SMALL_SIZE_LIMIT) {

            byte[] buffer = smallByteBuffer;

            smallByteBuffer = null;

            return buffer;

        }

        else if (size <= MEDIUM_SIZE_LIMIT) {

            byte[] buffer = mediumByteBuffer;

            mediumByteBuffer = null;

            return buffer;

        }

        else if (size <= LARGE_SIZE_LIMIT) {

            byte[] buffer = largeByteBuffer;

            largeByteBuffer = null;

            return buffer;

        }

        return null;

    }

    public void returnByteBuffer(byte[] b) {

        if (b == null) {

            return;

        }

        if (b.length <= SMALL_SIZE_LIMIT) {

            smallByteBuffer = b;

        }

        else if (b.length <= MEDIUM_SIZE_LIMIT) {

            mediumByteBuffer = b;

        }

        else if (b.length <= LARGE_SIZE_LIMIT) {

            largeByteBuffer = b;

        }

    }

}