Package org.apache.hadoop.hbase.io.hfile

Class PreviousBlockCompressionRatePredicator

java.lang.Object

org.apache.hadoop.hbase.io.hfile.PreviousBlockCompressionRatePredicator

All Implemented Interfaces:

BlockCompressedSizePredicator

@Private
public class PreviousBlockCompressionRatePredicator
extends Object
implements BlockCompressedSizePredicator

This BlockCompressedSizePredicator implementation adjusts the block size limit based on the compression rate of the block contents read so far. For the first block, adjusted size would be zero, so it performs a compression of current block contents and calculate compression rate and adjusted size. For subsequent blocks, decision whether the block should be finished or not will be based on the compression rate calculated for the previous block.

Field Summary

Fields

Modifier and Type	Field	Description
private int	adjustedBlockSize
private int	compressionRatio
private int	configuredMaxBlockSize

Fields inherited from interface org.apache.hadoop.hbase.io.hfile.BlockCompressedSizePredicator

BLOCK_COMPRESSED_SIZE_PREDICATOR, MAX_BLOCK_SIZE_UNCOMPRESSED

Constructor Summary

Constructors

Constructor	Description
PreviousBlockCompressionRatePredicator()

Method Summary

Modifier and Type	Method	Description
boolean	shouldFinishBlock(int uncompressed)	Returns true if the passed uncompressed size is larger than the limit calculated by updateLatestBlockSizes.
void	updateLatestBlockSizes(HFileContext context, int uncompressed, int compressed)	Recalculates compression rate for the last block and adjusts the block size limit as: BLOCK_SIZE * (uncompressed/compressed).

Methods inherited from class java.lang.Object

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

Field Details

adjustedBlockSize

private int adjustedBlockSize

compressionRatio

private int compressionRatio

configuredMaxBlockSize

private int configuredMaxBlockSize

Constructor Details

PreviousBlockCompressionRatePredicator

public PreviousBlockCompressionRatePredicator()

Method Details

updateLatestBlockSizes

public void updateLatestBlockSizes(HFileContext context,
 int uncompressed,
 int compressed)

Recalculates compression rate for the last block and adjusts the block size limit as: BLOCK_SIZE * (uncompressed/compressed).

Specified by:

updateLatestBlockSizes in interface BlockCompressedSizePredicator

Parameters:

context - HFIleContext containing the configured max block size.

uncompressed - the uncompressed size of last block written.

compressed - the compressed size of last block written.

shouldFinishBlock

public boolean shouldFinishBlock(int uncompressed)

Returns true if the passed uncompressed size is larger than the limit calculated by updateLatestBlockSizes.

Specified by:

shouldFinishBlock in interface BlockCompressedSizePredicator

Parameters:

uncompressed - true if the block should be finished.