org.apache.hadoop.hbase.io.hfile

Class PreviousBlockCompressionRatePredicator

java.lang.Object

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

All Implemented Interfaces:

BlockCompressedSizePredicator

@InterfaceAudience.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 inherited from interface org.apache.hadoop.hbase.io.hfile.BlockCompressedSizePredicator

BLOCK_COMPRESSED_SIZE_PREDICATOR, MAX_BLOCK_SIZE_UNCOMPRESSED

Constructor Summary

Constructors

Constructor and Description
PreviousBlockCompressionRatePredicator()

Method Summary

Modifier and Type	Method and 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

Constructor Detail

PreviousBlockCompressionRatePredicator

public PreviousBlockCompressionRatePredicator()

Method Detail

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.