com.espertech.esper.epl.db

Class DataCacheClearableMap

java.lang.Object

com.espertech.esper.epl.db.DataCacheClearableMap

All Implemented Interfaces:

DataCache

public class DataCacheClearableMap
extends Object
implements DataCache

For use in iteration over historical joins, a DataCache implementation that serves to hold EventBean rows generated during a join evaluation involving historical streams stable for the same cache lookup keys.

Constructor Summary

Constructors

Constructor and Description
DataCacheClearableMap() Ctor.

Method Summary

Modifier and Type	Method and Description
void	clear() Clears the cache.
void	destroy()
EventTable[]	getCached(Object[] methodParams, int numLookupKeys) Ask the cache if the keyed value is cached, returning a list or rows if the key is in the cache, or returning null to indicate no such key cached.
boolean	isActive() Returns true if the cache is active and currently caching, or false if the cache is inactive and not currently caching
void	put(Object[] methodParams, int numLookupKeys, EventTable[] rows) Puts into the cache a key and a list of rows, or an empty list if zero rows.

Methods inherited from class java.lang.Object

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

Constructor Detail

DataCacheClearableMap

public DataCacheClearableMap()

Ctor.

Method Detail

getCached

public EventTable[] getCached(Object[] methodParams,
                              int numLookupKeys)

Description copied from interface: DataCache

Ask the cache if the keyed value is cached, returning a list or rows if the key is in the cache, or returning null to indicate no such key cached. Zero rows may also be cached.

Specified by:

getCached in interface DataCache

Parameters:

methodParams - is the keys to look up in the cache

numLookupKeys - number of method param keys, from the start, that are for cache lookup

Returns:

a list of rows that can be empty is the key was found in the cache, or null if the key is not found in the cache

put

public void put(Object[] methodParams,
                int numLookupKeys,
                EventTable[] rows)

Description copied from interface: DataCache

Puts into the cache a key and a list of rows, or an empty list if zero rows.

The put method is designed to be called when the cache does not contain a key as determined by the get method. Implementations typically simply overwrite any keys put into the cache that already existed in the cache.

Specified by:

put in interface DataCache

Parameters:

methodParams - is the keys to the cache entry

numLookupKeys - number of method param keys, from the start, that are for cache lookup

rows - is a number of rows

isActive

public boolean isActive()

Description copied from interface: DataCache

Returns true if the cache is active and currently caching, or false if the cache is inactive and not currently caching

Specified by:

isActive in interface DataCache

Returns:

true for caching enabled, false for no caching taking place

clear

public void clear()

Clears the cache.

destroy

public void destroy()

Specified by:

destroy in interface DataCache