org.apache.openjpa.jdbc.kernel
Class PreparedQueryCacheImpl

java.lang.Object
  org.apache.openjpa.jdbc.kernel.PreparedQueryCacheImpl

All Implemented Interfaces:

PreparedQueryCache, Configurable

public class PreparedQueryCacheImpl
extends Object
implements PreparedQueryCache

An implementation of the cache of prepared queries.

Since:

2.0.0

Author:

Pinaki Poddar

Nested Class Summary

static class	PreparedQueryCacheImpl.StrongExclusion Strong exclusion.
static class	PreparedQueryCacheImpl.WeakExclusion Weak exclusion.

Nested classes/interfaces inherited from interface org.apache.openjpa.kernel.PreparedQueryCache

PreparedQueryCache.Exclusion

Constructor Summary

PreparedQueryCacheImpl()

Method Summary

void	addExclusionPattern(String pattern) Adds a pattern for exclusion.
boolean	cache(PreparedQuery q) Cache the given query keyed by its identifier.
void	clear() Clears all cached queries.
void	endConfiguration() Invoked upon completion of bean property configuration for this object.
PreparedQuery	get(String id) Get the PreparedQuery with the given identifier if it exists.
boolean	getEnableStatistics() Affirm if statistics is gathered.
List<PreparedQueryCache.Exclusion>	getExcludes() Gets the exclusion patterns.
Map<String,String>	getMapView() Get a map view of the cached queries indexed by identifier.
QueryStatistics<String>	getStatistics() Gets the simple statistics for executed queries.
PreparedQuery	initialize(String key, Object result) Initialize the cached Prepared Query registered with the given key earlier by the given execution result.
boolean	invalidate(String id) Remove the PreparedQuery with the given identifier from this cache.
Boolean	isCachable(String id) Affirms if a PreparedQuery can be cached against the given key.
PreparedQueryCache.Exclusion	isExcluded(String id) Returns the exclusion status of if the given query key.
(package private) boolean	isHinted(FetchConfiguration fetch, String hint)
protected void	lock(boolean readOnly) Note: Care needs to be taken so that a read lock is never held while requesting a write lock.
PreparedQuery	markUncachable(String id, PreparedQueryCache.Exclusion exclusion) Marks the given key as not amenable to caching.
(package private) boolean	matches(String pattern, String target)
Boolean	register(String id, Query query, FetchConfiguration hints) Register the given query for caching against the given key if it has not already been cached.
void	removeExclusionPattern(String pattern) Removes a pattern for exclusion.
void	setConfiguration(Configuration conf) Invoked prior to setting bean properties.
void	setEnableStatistics(boolean enable) Enable/disable gathering of statistics.
void	setExcludes(String excludes) Sets one or more exclusion regular expression patterns separated by semicolon.
void	startConfiguration() Invoked before bean property configuration is begun on this object.
protected void	unlock(boolean readOnly)

Methods inherited from class java.lang.Object

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

Constructor Detail

PreparedQueryCacheImpl

public PreparedQueryCacheImpl()

Method Detail

register

public Boolean register(String id,
                        Query query,
                        FetchConfiguration hints)

Description copied from interface: PreparedQueryCache

Register the given query for caching against the given key if it has not already been cached. If the query can not be cached, then mark it as such to avoid computing for the same key again.

Specified by:

register in interface PreparedQueryCache

Returns:

TRUE the query is registered in the cache by this call null if the query is already registered in the cache FALSE if can not be registered in the cache, either because it is known not to be cacheable from a previous attempt or a hint is given to ignore the cached version.

getMapView

public Map<String,String> getMapView()

Description copied from interface: PreparedQueryCache

Get a map view of the cached queries indexed by identifier.

Specified by:

getMapView in interface PreparedQueryCache

cache

public boolean cache(PreparedQuery q)

Cache the given query keyed by its identifier. Does not cache if the identifier matches any exclusion pattern or has been marked as non-cachable. Also register the identifier as not cachable against the matched exclusion pattern.

Specified by:

cache in interface PreparedQueryCache

Returns:

true if the given query is cached. false if it can not be cached due to exclusion.

See Also:

#markUncachable(String), PreparedQueryCache.setExcludes(String), PreparedQueryCache.addExclusionPattern(String)

initialize

public PreparedQuery initialize(String key,
                                Object result)

Description copied from interface: PreparedQueryCache

Initialize the cached Prepared Query registered with the given key earlier by the given execution result. If it is not possible to initialize the Prepared Query from the given execution result, then the corresponding key will be marked as invalid for caching.

Specified by:

initialize in interface PreparedQueryCache

Parameters:

key - the key used during registration

result - an opaque instance carrying the execution result of the original query.

Returns:

the initialized Prepared Query. If it is not possible to initialize the cached, possibly hollow Prepared Query from the given result, return null.

invalidate

public boolean invalidate(String id)

Description copied from interface: PreparedQueryCache

Remove the PreparedQuery with the given identifier from this cache.

Specified by:

invalidate in interface PreparedQueryCache

get

public PreparedQuery get(String id)

Description copied from interface: PreparedQueryCache

Get the PreparedQuery with the given identifier if it exists. null otherwise.

Specified by:

get in interface PreparedQueryCache

isCachable

public Boolean isCachable(String id)

Description copied from interface: PreparedQueryCache

Affirms if a PreparedQuery can be cached against the given key.

Specified by:

isCachable in interface PreparedQueryCache

Returns:

Boolean.FALSE if the given key is explicitly marked before as not be cached or matches any of the exclusion patterns. Boolean.TRUE if the given key currently exists in the cache. Otherwise, return null implying this receiver can not determine whether this key can be cached on not.

markUncachable

public PreparedQuery markUncachable(String id,
                                    PreparedQueryCache.Exclusion exclusion)

Description copied from interface: PreparedQueryCache

Marks the given key as not amenable to caching. Explicit marking helps to avoid repeated computational cost of determining whether a query can be cached or not.

Specified by:

markUncachable in interface PreparedQueryCache

Parameters:

id - is the key to be excluded

exclusion - directs whether exclusion is irreversible or not.

Returns:

The value for the given key if it had been cached before. null otherwise.

isExcluded

public PreparedQueryCache.Exclusion isExcluded(String id)

Description copied from interface: PreparedQueryCache

Returns the exclusion status of if the given query key.

Specified by:

isExcluded in interface PreparedQueryCache

Returns:

null implies that the key is not excluded.

setExcludes

public void setExcludes(String excludes)

Description copied from interface: PreparedQueryCache

Sets one or more exclusion regular expression patterns separated by semicolon. Any existing cache entry whose key matches any of the given pattern will be marked non-cachable in a reversible manner.

Specified by:

setExcludes in interface PreparedQueryCache

getExcludes

public List<PreparedQueryCache.Exclusion> getExcludes()

Description copied from interface: PreparedQueryCache

Gets the exclusion patterns.

Specified by:

getExcludes in interface PreparedQueryCache

addExclusionPattern

public void addExclusionPattern(String pattern)

Adds a pattern for exclusion. Any query cached currently whose identifier matches the given pattern will be marked invalidated as a side-effect.

Specified by:

addExclusionPattern in interface PreparedQueryCache

removeExclusionPattern

public void removeExclusionPattern(String pattern)

Removes a pattern for exclusion. Any query identifier marked as not cachable due to the given pattern will now be removed from the list of uncachables as a side-effect.

Specified by:

removeExclusionPattern in interface PreparedQueryCache

See Also:

PreparedQueryCache.markUncachable(String, Exclusion)

getStatistics

public QueryStatistics<String> getStatistics()

Description copied from interface: PreparedQueryCache

Gets the simple statistics for executed queries. If the statistics gathering is disabled, an empty statistics is returned.

Specified by:

getStatistics in interface PreparedQueryCache

lock

protected void lock(boolean readOnly)

Note: Care needs to be taken so that a read lock is never held while requesting a write lock. This will result in a deadlock.

Parameters:

readOnly - - If true, a read lock will be acquired. Else a write lock will be acquired.

unlock

protected void unlock(boolean readOnly)

Parameters:

readOnly - - If true, the read lock will be released. Else a write lock will be released.

matches

boolean matches(String pattern,
                String target)

isHinted

boolean isHinted(FetchConfiguration fetch,
                 String hint)

clear

public void clear()

Description copied from interface: PreparedQueryCache

Clears all cached queries.

Specified by:

clear in interface PreparedQueryCache

setEnableStatistics

public void setEnableStatistics(boolean enable)

Description copied from interface: PreparedQueryCache

Enable/disable gathering of statistics.

Specified by:

setEnableStatistics in interface PreparedQueryCache

getEnableStatistics

public boolean getEnableStatistics()

Description copied from interface: PreparedQueryCache

Affirm if statistics is gathered.

Specified by:

getEnableStatistics in interface PreparedQueryCache

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