Package com.linkedin.venice.kafka.validation.checksum

Class AdHash

java.lang.Object

com.linkedin.venice.kafka.validation.checksum.CheckSum

com.linkedin.venice.kafka.validation.checksum.AdHash

public class AdHash
extends CheckSum

This class AdHash is used to keep track of the checksum of the data incrementally. It adopts the idea of AdHash that: " A message x' which I want to hash may be a simple modification of a message x which I previously hashed. If I have already computed the hash f(x) of x then, rather than re-computing f(x') from scratch, I would like to just quickly 'update' the old hash value f(x) to the new value f(x'). An incremental hash function is one that permits this. " See the paper for details: A New Paradigm for Collision-free Hashing: Incrementality at Reduced Cost. (https://cseweb.ucsd.edu/~daniele/papers/IncHash.pdf) Its adoption in ZooKeeper: Verify, And Then Trust: Data Inconsistency Detection in ZooKeeper. (https://dl.acm.org/doi/abs/10.1145/3578358.3591328)

Constructor Summary

Constructors

Constructor	Description
AdHash()
AdHash(byte[] encodedState)

Method Summary

Modifier and Type	Method	Description
byte[]	getEncodedState()
byte[]	getFinalCheckSum()
CheckSumType	getType()
void	resetInternal()
void	updateChecksum(byte[] input, int startIndex, int length)	Update the checksum with the input data.

Methods inherited from class com.linkedin.venice.kafka.validation.checksum.CheckSum

getCheckSum, getInstance, getInstance, reset, toString, update, update, update, update

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

AdHash

public AdHash()

AdHash

public AdHash(byte[] encodedState)

Method Details

getFinalCheckSum

public byte[] getFinalCheckSum()

Specified by:

getFinalCheckSum in class CheckSum

updateChecksum

public void updateChecksum(byte[] input,
 int startIndex,
 int length)

Update the checksum with the input data. Notice that the internal CRC32 object is reset everytime before updating the checksum. This is to ensure that the checksum is always calculated from the beginning of the data and checkpoint-able. This is not thread-safe, but the caller should ensure that the object is not shared.

Specified by:

updateChecksum in class CheckSum

resetInternal

public void resetInternal()

Specified by:

resetInternal in class CheckSum

getType

public CheckSumType getType()

Specified by:

getType in class CheckSum

getEncodedState

public byte[] getEncodedState()

Overrides:

getEncodedState in class CheckSum