BinaryTableTileCompressor.java

package nom.tam.image.compression.bintable;

/*
 * #%L
 * nom.tam FITS library
 * %%
 * Copyright (C) 1996 - 2021 nom-tam-fits
 * %%
 * This is free and unencumbered software released into the public domain.
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 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
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 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
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 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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import java.io.IOException;
import java.nio.ByteBuffer;

import nom.tam.fits.FitsException;
import nom.tam.image.compression.hdu.CompressedTableData;
import nom.tam.util.ArrayDataOutput;
import nom.tam.util.FitsOutputStream;
import nom.tam.util.ByteBufferOutputStream;
import nom.tam.util.ColumnTable;

public class BinaryTableTileCompressor extends BinaryTableTile {

    private static final int FACTOR_15 = 15;

    private static final int FACTOR_10 = 10;

    private static final int FACTOR_11 = 11;

    private static final int MINIMUM_EXTRA_SPACE = 1024;

    private final CompressedTableData binData;

    public BinaryTableTileCompressor(CompressedTableData binData, ColumnTable<?> columnTable, BinaryTableTileDescription description) {
        super(columnTable, description);
        this.binData = binData;
    }

    @Override
    public void run() {
        ByteBuffer buffer = ByteBuffer.wrap(new byte[getUncompressedSizeInBytes()]);
        try (ArrayDataOutput os = new FitsOutputStream(new ByteBufferOutputStream(buffer))) {
            this.data.write(os, this.rowStart, this.rowEnd, this.column);
        } catch (IOException e) {
            throw new IllegalStateException("could not write compressed data", e);
        }
        buffer.rewind();
        int spaceForCompression = getUncompressedSizeInBytes();
        // give the compression 10% more space and a minimum of 1024 bytes
        spaceForCompression = Math.max(spaceForCompression * FACTOR_11 / FACTOR_10, spaceForCompression + MINIMUM_EXTRA_SPACE);
        ByteBuffer compressedBuffer = ByteBuffer.wrap(new byte[spaceForCompression]);
        if (!getCompressorControl().compress(type.asTypedBuffer(buffer), compressedBuffer, null)) {
            // very bad case lets try again with 50% more space
            spaceForCompression = spaceForCompression * FACTOR_15 / FACTOR_10;
            compressedBuffer = ByteBuffer.wrap(new byte[spaceForCompression]);
            if (!getCompressorControl().compress(type.asTypedBuffer(buffer), compressedBuffer, null)) {
                throw new IllegalStateException("could not compress the tile with the requested algorithem!");
            }
        }
        byte[] compressedBytes = new byte[compressedBuffer.position()];
        compressedBuffer.rewind();
        compressedBuffer.get(compressedBytes);
        try {
            synchronized (this.binData) {
                this.binData.setElement(getTileIndex() - 1, this.column, compressedBytes);
            }
        } catch (FitsException e) {
            throw new IllegalStateException("could not include compressed data into the table", e);
        }
    }
}