com.datadoghq.sketch.ddsketch.store

Class PaginatedStore

java.lang.Object

com.datadoghq.sketch.ddsketch.store.PaginatedStore

All Implemented Interfaces:

Store

public final class PaginatedStore
extends java.lang.Object
implements Store

This is an unbounded store which allocates storage for counts in aligned pages stored in an array at offsets modulo the page size. This means that if a distribution has several modes, the cost of the storage for the space in between the modes is that of a null pointer per page, requiring 4-8 bytes (depending on CompressedOops, whether ZGC is used, and heap size) for each 1KB page.

On the contrary, if the data is uniformly distributed filling each page in a range [N, N + K * PAGE_SIZE) this store will require K * (20 + 4|8) extra space over UnboundedSizeDenseStore, because of the metadata overhead of the array headers and references to each page.

Constructor Summary

Constructors

Constructor and Description
PaginatedStore()

Method Summary

Modifier and Type	Method and Description
void	add(int index, double count) Updates the counter at the specified index.
void	clear() Zeros all counts in the store.
Store	copy()
void	encode(Output output, Flag.Type storeFlagType)
void	forEach(BinAcceptor acceptor) Supplies each bin to the acceptor
java.util.Iterator<Bin>	getAscendingIterator()
java.util.Iterator<Bin>	getDescendingIterator()
int	getMaxIndex()
int	getMinIndex()
double	getTotalCount()
boolean	isEmpty()
void	mergeWith(Store store) Merges another store into this one.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.datadoghq.sketch.ddsketch.store.Store

add, add, add, decodeAndMergeWith, getAscendingStream, getDescendingStream, getStream, serialize, serializedSize

Constructor Detail

PaginatedStore

public PaginatedStore()

Method Detail

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Store

Returns:

true iff the Store does not contain any non-zero counter

getMinIndex

public int getMinIndex()

Specified by:

getMinIndex in interface Store

Returns:

the index of the lowest non-zero counter

getMaxIndex

public int getMaxIndex()

Specified by:

getMaxIndex in interface Store

Returns:

the index of the highest non-zero counter

forEach

public void forEach(BinAcceptor acceptor)

Description copied from interface: Store

Supplies each bin to the acceptor

Specified by:

forEach in interface Store

Parameters:

acceptor - consumes this store's bins

getTotalCount

public double getTotalCount()

Specified by:

getTotalCount in interface Store

Returns:

the sum of the counters of this store

add

public void add(int index,
                double count)

Description copied from interface: Store

Updates the counter at the specified index.

Specified by:

add in interface Store

Parameters:

index - the index of the counter to be updated

count - a non-negative value

mergeWith

public void mergeWith(Store store)

Description copied from interface: Store

Merges another store into this one. This should be equivalent as running the add operations that have been run on the other store on this one.

Specified by:

mergeWith in interface Store

Parameters:

store - the store to be merged into this one

copy

public Store copy()

Specified by:

copy in interface Store

Returns:

a (deep) copy of this store

clear

public void clear()

Description copied from interface: Store

Zeros all counts in the store. The store behaves as if empty after this call, but no underlying storage is released.

Specified by:

clear in interface Store

getAscendingIterator

public java.util.Iterator<Bin> getAscendingIterator()

Specified by:

getAscendingIterator in interface Store

Returns:

an iterator that iterates over the non-empty bins of this store, from lowest to highest index

getDescendingIterator

public java.util.Iterator<Bin> getDescendingIterator()

Specified by:

getDescendingIterator in interface Store

Returns:

an iterator that iterates over the non-empty bins of this store, from highest to lowest index

encode

public void encode(Output output,
                   Flag.Type storeFlagType)
            throws java.io.IOException

Specified by:

encode in interface Store

Throws:

java.io.IOException