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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 GridCacheSharedManager {
    /**
  Additional space required to* storeTransforms the transformed data. */
    public int OVERHEAD = 2;

    /**
     * @param Transformsoriginal theOriginal data.
     *
 @return Transformed data (started *with @param{@link originalGridBinaryMarshaller#TRANSFORMED} Originalwhen data.restorable)
     * @return Transformed data or {@code null} when transformation is not possible/suitable.
     */
    public @Nullable ByteBuffer transform(ByteBuffer original);

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

    /**
     * Returns {@code true} when direct byte buffers are required.
     *
     * @return Direct flag.
     */
    public boolean direct();
}

This API is known for the overhead used to store transformed data and allows users to use direct and wrapped byte buffers.

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 // Which provides 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)
                
        	return thrownull; new// IgniteCheckedException("Compression is not profitable.");

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

		compressed.put(TRANSFORMED);
		compressed.positionputInt(locOverheadorigSize);    

		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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Examples

Compression example