com.slytechs.capture.file.indexer.SoftTable.java Source code

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Here is the source code for com.slytechs.capture.file.indexer.SoftTable.java

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/**
 * Copyright (C) 2007 Sly Technologies, Inc. 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 Lesser General Public License for more
 * details. You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
package com.slytechs.capture.file.indexer;

import java.io.IOException;
import java.lang.ref.SoftReference;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.slytechs.capture.file.editor.BasicRecordIterator;
import com.slytechs.capture.file.editor.PartialLoader;

/**
 * @author Mark Bednarczyk
 * @author Sly Technologies, Inc.
 */
public class SoftTable implements IndexTable {

    @SuppressWarnings("unused")
    private static final Log logger = LogFactory.getLog(SoftTable.class);

    private final int length;

    private final long first; // The first position is hard

    private final long last; // The last position is hard

    private SoftReference<long[]> positions;

    private final PartialLoader loader;

    /**
     * @param length
     */
    public SoftTable(final List<Long> list, PartialLoader loader) {
        this.loader = loader;
        this.length = list.size();
        this.first = list.get(0);
        this.last = list.get(list.size() - 1);

        final long[] positions = new long[length];
        for (int i = 0; i < list.size(); i++) {
            positions[i] = list.get(i);
        }

        this.positions = new SoftReference<long[]>(positions);
    }

    public long get(int index) throws IOException {

        final long[] positions = fetchIndexes();

        return positions[index];
    }

    /**
     * @param i
     * @param index
     * @throws IOException
     */
    private long[] fetchIndexes() throws IOException {
        if (this.positions.get() != null) {
            return positions.get(); // Nothing to do
        }

        final long[] positions = new long[length];
        // Arrays.fill(positions, -1);

        final BasicRecordIterator iterator = new BasicRecordIterator(loader, loader.getLengthGetter());

        iterator.setPosition(first);

        for (int i = 0; i < length; i++) {
            positions[i] = iterator.getPosition();

            if (iterator.hasNext() == false) {
                throw new IllegalStateException("Not enough records in loader, expected upto " + length);
            }

            iterator.skip();
        }

        this.positions = new SoftReference<long[]>(positions);

        //      logger.info("fetched: [" + positions[0] + "-" + (positions[length - 1])
        //          + "]");

        return positions;
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.slytechs.capture.file.indexer.IndexTable#search(long)
     */
    public long search(long position) throws IOException {
        if (position < first || position > last) {
            return -1;
        }

        ;

        return Arrays.binarySearch(fetchIndexes(), position);
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.slytechs.capture.file.indexer.IndexTable#keepInMemory(long, long)
     */
    public Object keepInMemory(long start, long length) throws IOException {
        return ((start < 0 || start > length) ? null : fetchIndexes());
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.slytechs.capture.file.indexer.IndexTable#getLength()
     */
    public long getLength() {
        return length;
    }
}