ID | IEP-97 |
Author | Anton Vinogradov |
Sponsor | |
Created | |
Status | DRAFT |
Customers may want to
user's data at the network and memory layer.
Ignite supports Disk Compression and Transparent Data Encryption, but they are able to transform the data at the persistent layer only.
To cover both layers (network and memory) and make the feature compatible with the existing data, it is proposed to transform/restore CacheObject's bytes on the fly.
A possible solution is to transform the byte arrays they provided during the marshaling/unmarshalling phase. This will cover both layers, messaging (network) and storage (in-memory + persist).
All we need is to cover all CacheObjects.
Most of them has the following structure:
protected Object val; // Unmarshalled value. protected byte[] valBytes; // Marshalled value bytes.
and all we need - is to add transformation during the marshaling/unmarshalling phase:
protected byte[] valueBytesFromValue(CacheObjectValueContext ctx) throws IgniteCheckedException { byte[] bytes = ctx.kernalContext().cacheObjects().marshal(ctx, val); return CacheObjectsTransformer.transformIfNecessary(bytes, ctx); } protected Object valueFromValueBytes(CacheObjectValueContext ctx, ClassLoader ldr) throws IgniteCheckedException { byte[] bytes = CacheObjectsTransformer.restoreIfNecessary(valBytes, ctx); return ctx.kernalContext().cacheObjects().unmarshal(ctx, bytes, ldr); } ... public void prepareMarshal(CacheObjectValueContext ctx) throws IgniteCheckedException { if (valBytes == null) valBytes = valueBytesFromValue(ctx); } ... public void finishUnmarshal(CacheObjectValueContext ctx, ClassLoader ldr) throws IgniteCheckedException { if (val == null) val = valueFromValueBytes(ctx, ldr); }
BinaryObject(Impl)s have the different structure:
private Object obj; // Deserialized value. private byte[] arr; // Serialized bytes.
(De)serialization is a simmilar to (un)marshalling, it's a process to gain java class instance from bytes and or vice versa, but it happen at different time and code layer.
(Un)marshalling happens on putting/getting object to/from cache, but (de)serialization happens on building/deserializing of a binary object detached from any cache.
A lucky circumstance, BinaryObjectImpl require no marshalling, serialization already generates byte which can be used as marshalled bytes.
But, if we're going to transform the data during the marshaling/unmarshalling phase we need to add additional data layer to the BinaryObjectImpl:
private Object obj; // Deserialized value. private byte[] arr; // Serialized bytes. private byte[] valBytes; // Marshalled value bytes.
Where valBytes == arr when transformation is disabled.
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 a object's value requred, for example, to provide hashCode/schemaId/typeId/objectField.
So, BinaryObjectImpl requres valBytes to arr conversion:
private byte[] arrayFromValueBytes(CacheObjectValueContext ctx) { return CacheObjectsTransformer.restoreIfNecessary(valBytes, ctx); } private byte[] valueBytesFromArray(CacheObjectValueContext ctx) { return CacheObjectsTransformer.transformIfNecessary(arr, start, arr.length, ctx); } ... public void finishUnmarshal(CacheObjectValueContext ctx, ClassLoader ldr) throws IgniteCheckedException { if (arr == null) arr = arrayFromValueBytes(ctx); } ... public void prepareMarshal(CacheObjectValueContext ctx) { if (valBytes == null) valBytes = valueBytesFromArray(ctx); }
Some customets may want to encrypt the data, some to compress, while some just keep it as is.
So, we must provide the simple way to append any transformation.
Simplest way is to use Service Provider Interface (IgniteSpi):
public interface CacheObjectTransformerSpi extends IgniteSpi { /** Additional space required to store the transformed data. */ public int OVERHEAD = 6; /** * 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 ending with the transformed data. * @param offset Transformed data offset. * @param length Original data length. * @return Byte array contains the restored data. */ public byte[] restore(byte[] bytes, int offset, int length); }
public abstract class CacheObjectTransformerSpiAdapter extends IgniteSpiAdapter implements CacheObjectTransformerSpi { ... /** * 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. * @param length Original data length. * @return Restored data. */ protected abstract ByteBuffer restore(ByteBuffer transformed, int length); }
Transformation requires additional memory allocation and subsequent GC work.
Transformation requires additional CPU utilization.
// Links to discussions on the devlist, if applicable.
// Links to various reference documents, if applicable.