kodo.datacache
Class AbstractQueryCache

java.lang.Object
  |
  +--serp.util.AbstractEventManager
        |
        +--kodo.datacache.AbstractQueryCache

All Implemented Interfaces:

com.solarmetric.util.Closeable, Configurable, QueryCache

Direct Known Subclasses:

GemFireQueryCache, QueryCacheImpl, TangosolQueryCache

public abstract class AbstractQueryCache

extends serp.util.AbstractEventManager

implements QueryCache, Configurable

Abstract QueryCache implementation that provides various statistics, logging, and timeout functionality common across cache implementations.

Field Summary

protected JDOConfiguration	conf The configuration set by the system.
protected Log	log The log to use.

Constructor Summary

AbstractQueryCache()

Method Summary

void	addExpirationListener(ExpirationListener listen) Add a new expiration event listener to this cache.
void	afterCommit(RemoteCommitEvent event) This method is part of the RemoteCommitListener interface.
void	classesChanged(Collection classes) Tells the cache that all the classes in the classes set have been changed.
void	clear() Remove all data from this cache.
protected abstract void	clearInternal() Clear the cache.
void	close() Free the resources used by this cache.
protected void	closeWithoutClear()
void	endConfiguration() Invoked upon completion of bean property configuration for this object.
protected void	fireEvent(Object event, Object listener)
QueryResult	get(QueryKey key) Return a list of oids for the given query key.
double	getHitRate() Returns the percentage of hits.
int	getHits() Returns the number of cache hits for invocations of the get(kodo.datacache.QueryKey) method.
protected abstract QueryResult	getInternal(QueryKey qk) Return the list for the given key.
int	getMisses() Returns the number of cache misses for invocations of the get(kodo.datacache.QueryKey) method.
Collection	getStatistics() Get statistics exported by this object.
String	getStatisticsString() Returns a localized string containing the number of hits, the number of misses, and the hit ratio (hits / (hits+misses)).
boolean	isClosed()
protected void	keyRemoved(Object key, boolean expired) Invoke when a key is removed from this cache.
protected abstract Collection	keySet() Return a threadsafe view of the keys in this cache.
protected Collection	newListenerCollection() Individual query results will be registered as expiration listeners.
boolean	pin(QueryKey key) Pin the value stored under qk into the cache.
protected abstract boolean	pinInternal(QueryKey qk) Pin an object to the cache.
QueryResult	put(QueryKey qk, QueryResult oids) Set the list of OIDs for the given query key.
protected abstract QueryResult	putInternal(QueryKey qk, QueryResult oids) Add the given result to the cache, returning the old result under the given key.
QueryResult	remove(QueryKey key) Remove the value stored under the given query key.
protected void	removeAllInternal(Collection qks) Remove all results under the given keys from the cache.
boolean	removeExpirationListener(ExpirationListener listen) Remove an expiration event listener from this cache.
protected abstract QueryResult	removeInternal(QueryKey qk) Remove the result under the given key from the cache.
void	resetStatistics() Reset the caching statistics.
void	setConfiguration(Configuration conf) Invoked prior to setting bean properties.
void	startConfiguration() Invoked before bean property configuration is begun on this object.
boolean	unpin(QueryKey key) Unpin the value stored under key into the cache.
protected abstract boolean	unpinInternal(QueryKey qk) Unpin an object from the cache.

Methods inherited from class serp.util.AbstractEventManager

fireEvent, getListeners, hasListener, hasListeners, registerListener, removeListener

Methods inherited from class java.lang.Object

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

Field Detail

conf

protected JDOConfiguration conf

The configuration set by the system.

log

protected Log log

The log to use.

Constructor Detail

AbstractQueryCache

public AbstractQueryCache()

Method Detail

classesChanged

public void classesChanged(Collection classes)

Description copied from interface: QueryCache

Tells the cache that all the classes in the classes set have been changed. This could mean that items have been updated, deleted, or added. This limits the QueryCache to only be able to invalidate cached queries -- because the cache is not notified of actual changes, it cannot recompute query results.

After this method is invoked, all cached results that correspond to queries that use one of the classes in classes will be dropped.

Specified by:

classesChanged in interface QueryCache

Following copied from interface: kodo.datacache.QueryCache

Parameters:

classes - a set of Class objects that correspond to instances that have changed

get

public QueryResult get(QueryKey key)

Description copied from interface: QueryCache

Return a list of oids for the given query key. This is an unmodifiable list.

Specified by:

get in interface QueryCache

Following copied from interface: kodo.datacache.QueryCache

Returns:

The query results matching the given key, or null if none

put

public QueryResult put(QueryKey qk,
                       QueryResult oids)

Description copied from interface: QueryCache

Set the list of OIDs for the given query key. A reference to the given list will be stored in the query cache, so the list should not be modified after invoking this method.

Specified by:

put in interface QueryCache

Following copied from interface: kodo.datacache.QueryCache

Returns:

The previously cached value, or null if the key was not previously cached. See Map.put(java.lang.Object, java.lang.Object) for more information.

remove

public QueryResult remove(QueryKey key)

Description copied from interface: QueryCache

Remove the value stored under the given query key.

This method is typically not invoked directly from outside the QueryCache class. Instead, the cache should be updated by invoking #notifyChangedClasses, which will result in all queries that may be invalid being dropped.

Specified by:

remove in interface QueryCache

Following copied from interface: kodo.datacache.QueryCache

Returns:

The previously cached value, or null if the key was not previously cached. See Map.remove(java.lang.Object) for more information.

pin

public boolean pin(QueryKey key)

Description copied from interface: QueryCache

Pin the value stored under qk into the cache. This method guarantees that qk's value will not be expired if the cache exceeds its capacity. It causes this data to be ignored when determining whether or not the cache is full, effectively increasing the total amount of data stored in the cache. This method does not affect the behavior of QueryCache.remove(kodo.datacache.QueryKey) or #notifyChangedClasses.

Specified by:

pin in interface QueryCache

Following copied from interface: kodo.datacache.QueryCache

Returns:

true if key's value was pinned into the cache; false if the key is not in the cache.

unpin

public boolean unpin(QueryKey key)

Description copied from interface: QueryCache

Unpin the value stored under key into the cache. This method reverses a previous invocation of QueryCache.pin(kodo.datacache.QueryKey). This method does not remove anything from the cache; it merely makes key's value a candidate for flushing from the cache.

Specified by:

unpin in interface QueryCache

Following copied from interface: kodo.datacache.QueryCache

Returns:

true if key's value was unpinned from the cache; false if the key is not in the cache.

clear

public void clear()

Description copied from interface: QueryCache

Remove all data from this cache.

Specified by:

clear in interface QueryCache

close

public void close()

Description copied from interface: QueryCache

Free the resources used by this cache.

Specified by:

close in interface QueryCache

closeWithoutClear

protected void closeWithoutClear()

isClosed

public boolean isClosed()

addExpirationListener

public void addExpirationListener(ExpirationListener listen)

Description copied from interface: QueryCache

Add a new expiration event listener to this cache.

Specified by:

addExpirationListener in interface QueryCache

removeExpirationListener

public boolean removeExpirationListener(ExpirationListener listen)

Description copied from interface: QueryCache

Remove an expiration event listener from this cache.

Specified by:

removeExpirationListener in interface QueryCache

afterCommit

public void afterCommit(RemoteCommitEvent event)

This method is part of the RemoteCommitListener interface. If your cache subclass relies on Kodo for clustering support, make it implement RemoteCommitListener. This method will take care of invalidating entries from remote commits, by delegating to classesChanged(java.util.Collection).

keyRemoved

protected void keyRemoved(Object key,
                          boolean expired)

Invoke when a key is removed from this cache. Propagates the expiration event on to all expiration listeners registered with this class.

keySet

protected abstract Collection keySet()

Return a threadsafe view of the keys in this cache. This collection must be iteratable without risk of concurrent modification exceptions. It does not have to implement contains() efficiently or use set semantics.

getInternal

protected abstract QueryResult getInternal(QueryKey qk)

Return the list for the given key.

putInternal

protected abstract QueryResult putInternal(QueryKey qk,
                                           QueryResult oids)

Add the given result to the cache, returning the old result under the given key.

removeInternal

protected abstract QueryResult removeInternal(QueryKey qk)

Remove the result under the given key from the cache.

removeAllInternal

protected void removeAllInternal(Collection qks)

Remove all results under the given keys from the cache.

clearInternal

protected abstract void clearInternal()

Clear the cache.

pinInternal

protected abstract boolean pinInternal(QueryKey qk)

Pin an object to the cache.

unpinInternal

protected abstract boolean unpinInternal(QueryKey qk)

Unpin an object from the cache.

getHits

public int getHits()

Returns the number of cache hits for invocations of the get(kodo.datacache.QueryKey) method.

getMisses

public int getMisses()

Returns the number of cache misses for invocations of the get(kodo.datacache.QueryKey) method.

getHitRate

public double getHitRate()

Returns the percentage of hits.

getStatisticsString

public String getStatisticsString()

Returns a localized string containing the number of hits, the number of misses, and the hit ratio (hits / (hits+misses)).

getStatistics

public Collection getStatistics()

Get statistics exported by this object.

resetStatistics

public void resetStatistics()

Reset the caching statistics.

setConfiguration

public void setConfiguration(Configuration conf)

Description copied from interface: Configurable

Invoked prior to setting bean properties.

Specified by:

setConfiguration in interface Configurable

startConfiguration

public void startConfiguration()

Description copied from interface: Configurable

Invoked before bean property configuration is begun on this object.

Specified by:

startConfiguration in interface Configurable

endConfiguration

public void endConfiguration()

Description copied from interface: Configurable

Invoked upon completion of bean property configuration for this object.

Specified by:

endConfiguration in interface Configurable

fireEvent

protected void fireEvent(Object event,
                         Object listener)

Overrides:

fireEvent in class serp.util.AbstractEventManager

newListenerCollection

protected Collection newListenerCollection()

Individual query results will be registered as expiration listeners. We want such query results to be gc'ed once the only reference is held by the list of expiration listeners.

Overrides:

newListenerCollection in class serp.util.AbstractEventManager