org.waarp.ftp.core.data.handler.FtpSeekAheadData.java Source code

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Here is the source code for org.waarp.ftp.core.data.handler.FtpSeekAheadData.java

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/**
 * This file is part of Waarp Project.
 * 
 * Copyright 2009, Frederic Bregier, and individual contributors by the @author tags. See the
 * COPYRIGHT.txt in the distribution for a full listing of individual contributors.
 * 
 * All Waarp Project is free software: you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 * 
 * Waarp 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 General Public License along with Waarp . If not, see
 * <http://www.gnu.org/licenses/>.
 */
package org.waarp.ftp.core.data.handler;

import io.netty.buffer.ByteBuf;

/**
 * SeekAheadData Class used to optimize access to the incoming buffer
 * 
 * @author Frederic Bregier
 * 
 */
public class FtpSeekAheadData {
    /**
     * Exception when NO Backend Array is found
     */
    static class SeekAheadNoBackArrayException extends Exception {
        private static final long serialVersionUID = -630418804938699495L;
    }

    byte[] bytes;

    int readerIndex;

    int pos;

    int limit;

    ByteBuf buffer;

    /**
     * @param buffer
     */
    FtpSeekAheadData(ByteBuf buffer) throws SeekAheadNoBackArrayException {
        if (!buffer.hasArray()) {
            throw new SeekAheadNoBackArrayException();
        }
        this.buffer = buffer;
        this.bytes = buffer.array();
        this.pos = this.readerIndex = buffer.arrayOffset() + buffer.readerIndex();
        this.limit = buffer.arrayOffset() + buffer.writerIndex();
    }

    /**
     * 
     * @param minus
     *            this value will be used as (currentPos - minus) to set the current readerIndex in
     *            the buffer.
     */
    void setReadPosition(int minus) {
        pos -= minus;
        readerIndex = pos;
        buffer.readerIndex(readerIndex);
    }

    void clear() {
        this.buffer = null;
        this.bytes = null;
        this.limit = 0;
        this.pos = 0;
        this.readerIndex = 0;
    }
}