Package com.espertech.esper.common.internal.epl.historical.datacache

Class HistoricalDataCacheExpiringImpl

java.lang.Object

com.espertech.esper.common.internal.epl.historical.datacache.HistoricalDataCacheExpiringImpl

All Implemented Interfaces:

HistoricalDataCache, ScheduleHandleCallback

public class HistoricalDataCacheExpiringImpl
extends Object
implements HistoricalDataCache, ScheduleHandleCallback

Implements an expiry-time cache that evicts data when data becomes stale after a given number of seconds.

The cache reference type indicates which backing Map is used: Weak type uses the WeakHashMap, Soft type uses the apache commons ReferenceMap, and Hard type simply uses a HashMap.

Constructor Summary

Constructors

Constructor	Description
HistoricalDataCacheExpiringImpl(double maxAgeSec, double purgeIntervalSec, CacheReferenceType cacheReferenceType, AgentInstanceContext agentInstanceContext, long scheduleSlot)	Ctor.

Method Summary

Modifier and Type	Method	Description
void	destroy()
EventTable[]	getCached(Object methodParams)	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.
protected double	getMaxAgeSec()	Returns the maximum age in milliseconds.
double	getPurgeIntervalSec()
protected long	getSize()	Returns the current 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, EventTable[] rows)	Puts into the cache a key and a list of rows, or an empty list if zero rows.
void	scheduledTrigger()	Callback that is invoked as indicated by a schedule added to the scheduling service.

Methods inherited from class java.lang.Object

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

Constructor Details

HistoricalDataCacheExpiringImpl

public HistoricalDataCacheExpiringImpl(double maxAgeSec,
 double purgeIntervalSec,
 CacheReferenceType cacheReferenceType,
 AgentInstanceContext agentInstanceContext,
 long scheduleSlot)

Ctor.

Parameters:

maxAgeSec - is the maximum age in seconds

purgeIntervalSec - is the purge interval in seconds

cacheReferenceType - indicates whether hard, soft or weak references are used in the cache

agentInstanceContext - agent instance context

scheduleSlot - slot for scheduling callbacks for this cache

Method Details

getCached

public EventTable[] getCached(Object methodParams)

Description copied from interface: HistoricalDataCache

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 HistoricalDataCache

Parameters:

methodParams - is the keys to look up in the cache

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,
 EventTable[] rows)

Description copied from interface: HistoricalDataCache

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 HistoricalDataCache

Parameters:

methodParams - is the keys to the cache entry

rows - is a number of rows

getMaxAgeSec

protected double getMaxAgeSec()

Returns the maximum age in milliseconds.

Returns:

millisecon max age

getPurgeIntervalSec

public double getPurgeIntervalSec()

isActive

public boolean isActive()

Description copied from interface: HistoricalDataCache

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 HistoricalDataCache

Returns:

true for caching enabled, false for no caching taking place

getSize

protected long getSize()

Returns the current cache size.

Returns:

cache size

scheduledTrigger

public void scheduledTrigger()

Description copied from interface: ScheduleHandleCallback

Callback that is invoked as indicated by a schedule added to the scheduling service.

Specified by:

scheduledTrigger in interface ScheduleHandleCallback

destroy

public void destroy()

Specified by:

destroy in interface HistoricalDataCache