com.devexperts.qd.kit

Class HashStriper

java.lang.Object

com.devexperts.qd.kit.HashStriper

All Implemented Interfaces:

SymbolStriper

public class HashStriper
extends Object
implements SymbolStriper

Strategy that splits symbol universe into stripes by hash groups.

Example: striper byhash16 splits the symbol universe into 16 stripes by hash.

HashStriper can be matched by the following regex: byhash([0-9]+), where the matched group defines the number of stripes (must be a power of 2).

See Also:

HashFilter

Field Summary

Fields

Modifier and Type	Field and Description
static String	HASH_STRIPER_PREFIX

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	HashStriper(DataScheme scheme, int stripeCount)

Method Summary

Modifier and Type	Method and Description
BitSet	getIntersectingStripes(QDFilter filter) Returns bit set of SymbolStriper.getStripeCount() size that specifies stripes that intersect with the given filter.
String	getName() Returns a string representation of this striper.
DataScheme	getScheme() Returns scheme that this striper works for.
protected int	getShift()
int	getStripeCount() Returns the positive number of stripes that this striper splits into.
QDFilter	getStripeFilter(int stripeIndex) Returns filter corresponding for the given stripe index.
int	getStripeIndex(char[] chars, int offset, int length) Returns the index of the stripe that the given symbol (represented as character array) falls into.
int	getStripeIndex(int cipher, String symbol) Returns the index of the stripe that the given cipher-symbol pair falls into.
int	getStripeIndex(String symbol) Returns the index of the stripe that the given symbol falls into.
protected static int	index(int hash, int shift)
String	toString() Returns a string representation of this striper.
static SymbolStriper	valueOf(DataScheme scheme, int stripeCount) Constructs a symbol striper for a given number of hash stripes.
static HashStriper	valueOf(DataScheme scheme, String spec) Parses a given specification as hash striper for a given scheme.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.devexperts.qd.SymbolStriper

definedValueOf

Field Detail

HASH_STRIPER_PREFIX

public static final String HASH_STRIPER_PREFIX

See Also:

Constant Field Values

Constructor Detail

HashStriper

protected HashStriper(DataScheme scheme,
                      int stripeCount)

Method Detail

valueOf

public static HashStriper valueOf(DataScheme scheme,
                                  String spec)

Parses a given specification as hash striper for a given scheme.

Specified by:

valueOf in interface SymbolStriper

Parameters:

scheme - the scheme.

spec - the striper specification.

Returns:

symbol striper.

Throws:

NullPointerException - if spec is null.

FilterSyntaxException - if spec is invalid.

valueOf

public static SymbolStriper valueOf(DataScheme scheme,
                                    int stripeCount)

Constructs a symbol striper for a given number of hash stripes. Note that if the number of stripes is 1 then MonoStriper.INSTANCE striper will be returned.

Parameters:

scheme - the scheme.

stripeCount - the number of hash stripes.

Returns:

symbol striper.

Throws:

FilterSyntaxException - if spec is invalid.

getName

public String getName()

Description copied from interface: SymbolStriper

Returns a string representation of this striper. This string representation should be parseable into this striper via SymbolStriperFactory.

Specified by:

getName in interface SymbolStriper

getScheme

public DataScheme getScheme()

Description copied from interface: SymbolStriper

Returns scheme that this striper works for. Returns null if this striper works for any scheme.

Specified by:

getScheme in interface SymbolStriper

getStripeCount

public int getStripeCount()

Description copied from interface: SymbolStriper

Returns the positive number of stripes that this striper splits into.

Specified by:

getStripeCount in interface SymbolStriper

Returns:

number of stripes (must be positive)

getStripeIndex

public int getStripeIndex(int cipher,
                          String symbol)

Description copied from interface: SymbolStriper

Returns the index of the stripe that the given cipher-symbol pair falls into.

Note that wildcard symbol should not be submitted to this method, since it should be accepted by all stripes therefore making stripes intersecting each other.

Specified by:

getStripeIndex in interface SymbolStriper

Parameters:

cipher - symbol cipher

symbol - symbol string

Returns:

stripe index

See Also:

QDFilter.accept(QDContract, DataRecord, int, String)

getStripeIndex

public int getStripeIndex(String symbol)

Description copied from interface: SymbolStriper

Returns the index of the stripe that the given symbol falls into.

Specified by:

getStripeIndex in interface SymbolStriper

Parameters:

symbol - symbol string (not-null)

Returns:

stripe index

See Also:

SymbolStriper.getStripeIndex(int, String)

getStripeIndex

public int getStripeIndex(char[] chars,
                          int offset,
                          int length)

Description copied from interface: SymbolStriper

Returns the index of the stripe that the given symbol (represented as character array) falls into.

Specified by:

getStripeIndex in interface SymbolStriper

Parameters:

chars - array that is the source of the symbol

offset - the initial offset

length - the symbol's length

Returns:

stripe index

See Also:

SymbolStriper.getStripeIndex(int, String)

getStripeFilter

public QDFilter getStripeFilter(int stripeIndex)

Description copied from interface: SymbolStriper

Returns filter corresponding for the given stripe index.

Specified by:

getStripeFilter in interface SymbolStriper

Parameters:

stripeIndex - stripe index

Returns:

QD filter for the stripe

getIntersectingStripes

public BitSet getIntersectingStripes(QDFilter filter)

Description copied from interface: SymbolStriper

Returns bit set of SymbolStriper.getStripeCount() size that specifies stripes that intersect with the given filter. If intersection cannot be calculated null can be returned.

Specified by:

getIntersectingStripes in interface SymbolStriper

Parameters:

filter - QD filter to check for intersection

Returns:

bitset of SymbolStriper.getStripeCount() size of intersecting stripes, or null.

toString

public String toString()

Description copied from interface: SymbolStriper

Returns a string representation of this striper.

Specified by:

toString in interface SymbolStriper

Overrides:

toString in class Object

See Also:

SymbolStriper.getName()

getShift

protected int getShift()

index

protected static int index(int hash,
                           int shift)