com.espertech.esper.epl.db

Class DataCacheLRUImpl

java.lang.Object

com.espertech.esper.epl.db.DataCacheLRUImpl

All Implemented Interfaces:

DataCache

public class DataCacheLRUImpl
extends Object
implements DataCache

Query result data cache implementation that uses a least-recently-used algorithm to store and evict query results.

Constructor Summary

Constructors

Constructor and Description
DataCacheLRUImpl(int cacheSize) Ctor.

Method Summary

Modifier and Type	Method and Description
void	destroy()
EventTable[]	getCached(Object[] methodParams, int numInputParameters) Retrieves an entry from the cache.
int	getCacheSize() Returns the maximum cache size.
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) Adds an entry to this cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

DataCacheLRUImpl

public DataCacheLRUImpl(int cacheSize)

Ctor.

Parameters:

cacheSize - is the maximum cache size

Method Detail

getCached

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

Retrieves an entry from the cache. The retrieved entry becomes the MRU (most recently used) entry.

Specified by:

getCached in interface DataCache

Parameters:

methodParams - the key whose associated value is to be returned.

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

Returns:

the value associated to this key, or null if no value with this key exists in the cache.

put

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

Adds an entry to this cache. If the cache is full, the LRU (least recently used) entry is dropped.

Specified by:

put in interface DataCache

Parameters:

methodParams - the keys with which the specified value is to be associated.

rows - a value to be associated with the specified key.

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

getCacheSize

public int getCacheSize()

Returns the maximum cache size.

Returns:

maximum cache size

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

destroy

public void destroy()

Specified by:

destroy in interface DataCache