Page History

public interface CacheObjectTransformer {
    /** Additional space required to store the transformed data. */
    public int OVERHEAD = 2;

    /**
     * Transforms the data.
     *
     * @param bytes  Byte array contains the data.
     * @param offset Data offset.
     * @param length Data length.
     * @return Byte array contains the transformed data started with non-filled area with {@link #OVERHEAD} size.
     * @throws IgniteCheckedException when transformation is not possible/suitable.
     */
    public byte[] transform(byte[] bytes, int offset, int length) throws IgniteCheckedException;      

    /**
     * Restores the data.
     *
     * @param bytes  Byte array contains the transformed data.
	 * @param offset Data offset.
     * @param length Data length.
     * @return Byte array contains the restored data.
     */
    public byte[] restore(byte[] bytes, int offset, int length);
}

public abstract class CacheObjectTransformerAdapter implements CacheObjectTransformer {
...
    /**
     * Transforms the data.
     *
     * @param original Original data.
     * @return Transformed data.
     * @throws IgniteCheckedException when transformation is not possible/suitable.
     */
    protected abstract ByteBuffer transform(ByteBuffer original) throws IgniteCheckedException;      

	/**
     * Restores the data.
     *
     * @param transformed Transformed data.
     * @return Restored data.
     */
    protected abstract ByteBuffer restore(ByteBuffer transformed); 
}

class CompressionTransformer extends CacheObjectTransformerAdapter {
	protected ByteBuffer transform(ByteBuffer original) throws IgniteCheckedException {                     
		int locOverhead = 4; // Original length.
        int totalOverhead = CacheObjectTransformer.OVERHEAD + locOverhead;

        int origSize = original.remaining();
        int lim = origSize - totalOverhead;          

		if (lim <= 0)
            throw new IgniteCheckedException("Compression is not profitable.");

        ByteBuffer compressed = byteBuffer(lim);

		compressed.position(locOverhead);

		Zstd.compress(compressed, original, 1);

        compressed.flip(); 

		compressed.putInt(origSize);

		compressed.rewind();          

        return compressed;
    }

    protected ByteBuffer restore(ByteBuffer transformed) {
        ByteBuffer restored = byteBuffer(transformed.getInt());

        Zstd.decompress(restored, transformed);

        restored.flip();
              
        return restored;
    }
}

class EncryptionTransformer extends CacheObjectTransformerAdapter {
    private static final int SHIFT = 42; // Secret!

    protected ByteBuffer transform(ByteBuffer original) throws IgniteCheckedException {
        ByteBuffer transformed = byteBuffer(original.remaining()); // Same capacity is required.

        while (original.hasRemaining())
            transformed.put((byte)(original.get() + SHIFT));

        transformed.flip();

        return transformed;
    }

    protected ByteBuffer restore(ByteBuffer transformed, int length) {
        ByteBuffer restored = byteBuffer(transformed.remaining()); // Same size.
		
		while (transformed.hasRemaining())
            restored.put((byte)(transformed.get() - SHIFT));

        restored.flip();

        return restored;
    }
}