Page History

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ID

IEP-97

Author

Sponsor

Created

22 Nov 2022

Status


colour	Green
title	active

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No-Op transformer will produce [-3, 0, 3, 42, 0, 0, 0] or [-3, 0, 9, 11, 0, 0, 0, 84, 101, 115, 116, 32, 115, 116, 114, 105, 110, 103], where 0 is a protocol version.
Pseudo-Crypto transformer, which adds 1 to every original byte, will produce [-3, 0, 4, 43, 1, 1, 1] or [-3, 0, 10, 12, 1, 1, 1, 85, 102, 116, 117, 33, 116, 117, 115, 106, 111, 104]
Magic-Compressor will produce [-3, 0, 7] or [-3, 0, 17], where 7 and 17 are the result of a magic compression.

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It's not possible to just replace arr with valBytes because, unlike , for example, from CacheObjectImpl arr is not just a mashalled bytes, it's an object's value that is required, for example, to provide hashCode/schemaId/typeId/objectField, and we must keep it as is.

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Code Block

language	java
title	Interface

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

GridCacheSharedManager {
    /**
     * Transforms the data.
     *
     * @param bytesoriginal  Byte array contains the data.
     * @param offset Data offset.
     * @param length Data lengthOriginal data.
     * @return Byte array contains the transformed Transformed data started with non-filled area(started with {@link #OVERHEADGridBinaryMarshaller#TRANSFORMED} when size.restorable)
     * or @throws{@code IgniteCheckedExceptionnull} when transformation is not possible/suitable.
     */
    public byte[]@Nullable ByteBuffer transform(byte[] bytes, int offset, int length) throws IgniteCheckedException;      ByteBuffer original);

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

This API is known for the overhead used to store transformed data and is able to work with byte arrays with custom offsets, which is necessary to guarantee performance.

Every customer may implement this interface in a proper way if necessary and specify it in the via plugin configuration:

Code Block

language	java
title	Custom transformer

IgniteConfiguration getConfiguration() {
	IgniteConfiguration cfg = ...

	cfg.setCacheObjectTransformersetPluginProviders(new XXXTransformerXXXPluginProvider());

	return cfg;
}

Simplified API

But, most customers just want to transform the data, so, they may extend the adapter with the simplified API:

Code Block

language	java
title	CacheObjectTransformerAdapter

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

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

    return cfg;
}

Examples

Compression example

Code Block

language	java
title	Compression

class CompressionTransformer extends CacheObjectTransformerAdapter {
	protected ByteBuffer transform(ByteBuffer original) throws IgniteCheckedException {                     
		int locOverheadoverhead = 45; // OriginalTransformed length.
flag        int totalOverhead = CacheObjectTransformer.OVERHEAD + locOverhead;+ length.

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

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

        ByteBuffer compressed = byteBuffer(lim);(overhead + (int)Zstd.compressBound(origSize));    

		compressed.position(locOverhead);put(TRANSFORMED);
		compressed.putInt(origSize);    

		int size = Zstd.compress(compressed, original, 1);

 		if (size >= lim)
        compressed.flip(); 

		compressed.putInt(origSize);	return null; // Compression is not profitable.          

		compressed.rewindflip();          

        return compressed;
    }

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

        Zstd.decompress(restored, transformed);

        restored.flip();
              
        return restored;
    }
}

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Code Block

language	java
title	Encryption

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

    protected ByteBuffer transform(ByteBuffer original) throws IgniteCheckedException {
        ByteBuffer transformed = byteBuffer(original.remaining() + 1); // Same capacity is required.

		transformed.put(TRANSFORMED);

        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;
    }
}

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Versions Compared

Old Version 67

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Key

Simplified API

Examples

Compression example