com.pervasive.datarush.tokens.record

Class RecordToIDMap

java.lang.Object

com.pervasive.datarush.tokens.record.RecordToIDMap

public final class RecordToIDMap
extends Object

Provides a mapping between records and integer ids. The keys are maintained in a space-efficient data structure in order to minimize the per-entry object overhead. By providing a mapping from record to IDs, this can be used as a building-block for a number of data structures and operator. The ids returned are from a zero-based, strictly monotonically increasing sequence such that they can be used as indexes into arrays that wish to associate additional information with the keys.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RecordToIDMap.ReadAccessor An accessor for performing lookup operations.
static class	RecordToIDMap.WriteAccessor An accessor for building the map.

Constructor Summary

Constructors

Constructor and Description
RecordToIDMap(RecordTokenType keyType, int initialCapacity) Create a new RecordToIDMap

Method Summary

Modifier and Type	Method and Description
RecordTokenType	getKeyType() Returns the type of keys contained within this map.
RecordValuedIterator	newIterator() Creates an iterator to iterate over keys within the map.
RecordToIDMap.WriteAccessor	newLRUWriteAccessor(RecordValued value, int maxSize) Creates an accessor for building the map.
RecordToIDMap.ReadAccessor	newReadAccessor(RecordValued value) Creates an accessor for performing lookup operations.
RecordToIDMap.WriteAccessor	newWriteAccessor(RecordValued value) Creates an accessor for building the map.
int	size() Creates the number of entries in the map.

Methods inherited from class java.lang.Object

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

Constructor Detail

RecordToIDMap

public RecordToIDMap(RecordTokenType keyType,
                     int initialCapacity)

Create a new RecordToIDMap

Parameters:

keyType - The record token type that corresponds to the keys that we are selecting. Must be a subset of values from the record input from which we are building/looking up.

initialCapacity - The initial capacity ( in records ) to use for the internal data structures of this mapping.

Method Detail

newReadAccessor

public RecordToIDMap.ReadAccessor newReadAccessor(RecordValued value)

Creates an accessor for performing lookup operations.

NOTE: From a thread safety standpoint, it is safe to have multiple ReadAccessors in different threads that reference a single RecordToIDMap. However, each thread must have its own ReadAccessor instance.

Parameters:

value - The record valued object for which we are performing lookup operations. Typically will be a RecordInput.

Returns:

the newly-created ReadAccessor

getKeyType

public RecordTokenType getKeyType()

Returns the type of keys contained within this map.

Returns:

the type of keys contained within this map.

newWriteAccessor

public RecordToIDMap.WriteAccessor newWriteAccessor(RecordValued value)

Creates an accessor for building the map.

NOTE: From a thread safety standpoint, it is unsafe to have multiple WriteAccessors in different threads that reference a single RecordToIDMap.

Parameters:

value - The record valued object from which we are building the map. Typically will be a RecordInput.

Returns:

the newly-created WriteAccessor

newLRUWriteAccessor

public RecordToIDMap.WriteAccessor newLRUWriteAccessor(RecordValued value,
                                                       int maxSize)

Creates an accessor for building the map.

NOTE: From a thread safety standpoint, it is unsafe to have multiple WriteAccessors in different threads that reference a single RecordToIDMap.

Parameters:

value - The record valued object from which we are building the map. Typically will be a RecordInput.

maxSize - The maximum number of items to keep in the map

Returns:

the newly-created WriteAccessor

newIterator

public RecordValuedIterator newIterator()

Creates an iterator to iterate over keys within the map. Keys will be returned in order by their associated ID. Moreover, the absolute index of the iterator will be equivalent to the ID.

Returns:

an iterator to iterate over keys within the map.

size

public int size()

Creates the number of entries in the map.

Returns:

the number of entries in the map.