org.hypergraphdb

Class HGConfiguration

java.lang.Object

org.hypergraphdb.HGConfiguration

public final class HGConfiguration
extends Object

A bean that holds configuration parameters for a HyperGraphDB initialization. An instance can be passed to the HGEnvironment.configure(String, HGConfiguration) or HGEnvironment.get(String, HGConfiguration) methods.

Author:

Borislav Iordanov

Constructor Summary

Constructors

Constructor and Description
HGConfiguration()

Method Summary

Methods

Modifier and Type	Method and Description
HGAtomCache	getCacheImplementation() Return the cache implementation configured for this HyperGraph instance.
boolean	getCancelMaintenance() Return true if HyperGraph will cancel maintenance operation when it is being open.
ClassLoader	getClassLoader() Return the configured Java class loader for use by this HyperGraphDB instance or null if no loader was configured.
HGEventManager	getEventManager() Return the HGEventManager to be used by the database.
HGHandleFactory	getHandleFactory() Return the handle factory configured for this database.
int	getMaxCachedIncidenceSetSize() Return the configured maximum size of atom incidence sets that are kept in RAM.
boolean	getPreventDanglingAtomReferences() Return true if the system should detect and throw an exception when a possible invalid HGAtomRef occurs.
HGQueryConfiguration	getQueryConfiguration() Return the HGQueryConfiguration associated with the HyperGraph instance.
boolean	getSkipMaintenance() Return true if HyperGraph should skip scheduled maintenance operations when it is open.
boolean	getSkipOpenedEvent() Return true if the startup process should NOT fire a HGOpenedEvent so none of the registered listeners will be triggered.
HGStoreImplementation	getStoreImplementation() Return the low-level storage implementation to be used for this database instance.
HGTypeConfiguration	getTypeConfiguration() Return the configuration bean for the type system.
boolean	isKeepIncidentLinksOnRemoval() Return true if links incident to an atom are kept in the database when that atom is being removed through the HyperGraph.remove(HGHandle) method and falseotherwise.
boolean	isTransactional() true if the database is configured to support transactions and false otherwise.
boolean	isUseSystemAtomAttributes() Return true (the default) if system-level atom attributes are stored and false otherwise.
void	resetDefaults() Set all parameters of this configuration to their default values.
void	setCacheImplementation(HGAtomCache cacheImplementation) Configure a cache implementation to be used for this HyperGraph instance.
void	setCancelMaintenance(boolean cancelMaintenance) Specify whether HyperGraph should cancel maintenance operation when it is being open.
void	setClassLoader(ClassLoader classLoader) Configure a ClassLoader for this HyperGraphDB instance.
void	setEventManager(HGEventManager eventManager) Specify the HGEventManager to be used by the database.
void	setHandleFactory(HGHandleFactory handleFactory) Set the persistent handle factory for this database.
void	setKeepIncidentLinksOnRemoval(boolean keepIncidentLinksOnRemoval) Specify whether links incident to an atom are kept in the database when that atom is being removed through the HyperGraph.remove(HGHandle) method.
void	setMaxCachedIncidenceSetSize(int maxCachedIncidenceSetSize) Set the configured maximum size of atom incidence sets that are kept in RAM.
void	setPreventDanglingAtomReferences(boolean preventDanglingAtomReferences) Specify whether the system should detect and throw an exception when a possible invalid HGAtomRef occurs.
void	setSkipMaintenance(boolean skipMaintenance) Specify whether HyperGraph should skip maintenance operation when it is being open.
void	setSkipOpenedEvent(boolean skipOpenedEvent) Specify whether the startup process should NOT fire a HGOpenedEvent so none of the registered listeners will be triggered.
void	setStoreImplementation(HGStoreImplementation storeImplementation) Specify the low-level storage implementation to be used for this database instance.
void	setTransactional(boolean transactional) Specifies if the database should be opened in transactional mode which is the default mode.
void	setUseSystemAtomAttributes(boolean useSystemAtomAttributes) Specify whether system-level atom attributes are stored - the default is true.

Methods inherited from class java.lang.Object

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

Constructor Detail

HGConfiguration

public HGConfiguration()

Method Detail

getHandleFactory

public HGHandleFactory getHandleFactory()

Return the handle factory configured for this database. If no factory has been explicitly configured, a default implementation based on UUIDs is provided.

setHandleFactory

public void setHandleFactory(HGHandleFactory handleFactory)

Set the persistent handle factory for this database.

Parameters:

handleFactory - The handle factory instance.

getStoreImplementation

public HGStoreImplementation getStoreImplementation()

Return the low-level storage implementation to be used for this database instance.

setStoreImplementation

public void setStoreImplementation(HGStoreImplementation storeImplementation)

Specify the low-level storage implementation to be used for this database instance.

Parameters:

storeImplementation -

resetDefaults

public void resetDefaults()

Set all parameters of this configuration to their default values.

isTransactional

public boolean isTransactional()

true if the database is configured to support transactions and false otherwise.

Returns:

setTransactional

public void setTransactional(boolean transactional)

Specifies if the database should be opened in transactional mode which is the default mode. Setting this flag to false should be done with care. It results in much faster operations (4-5 times faster), but it can result in an unrecoverable crash. In general this should be used when a lot of data is being loaded into a brand new, or a properly backed up beforehand, database.

Note that being transactional is not a property of the database instance, but rather of the current interaction session.

Parameters:

transactional -

getSkipMaintenance

public boolean getSkipMaintenance()

Return true if HyperGraph should skip scheduled maintenance operations when it is open. Return false otherwise.

setSkipMaintenance

public void setSkipMaintenance(boolean skipMaintenance)

Specify whether HyperGraph should skip maintenance operation when it is being open.

getCancelMaintenance

public boolean getCancelMaintenance()

Return true if HyperGraph will cancel maintenance operation when it is being open. Canceling maintenance operations will delete them so they'll never be run.

setCancelMaintenance

public void setCancelMaintenance(boolean cancelMaintenance)

Specify whether HyperGraph should cancel maintenance operation when it is being open. Canceling maintenance operations will delete them so they'll never be run.

getSkipOpenedEvent

public boolean getSkipOpenedEvent()

Return true if the startup process should NOT fire a HGOpenedEvent so none of the registered listeners will be triggered.

setSkipOpenedEvent

public void setSkipOpenedEvent(boolean skipOpenedEvent)

Specify whether the startup process should NOT fire a HGOpenedEvent so none of the registered listeners will be triggered. This is useful whenever a HyperGraphDB instance should be opened "merely" for examining/querying data and user-defined bootstrap operations are to be skipped.

Note that setting this flag to true is meaningful only when you have defined one or more listeners to the HGOpenedEvent. For example, a brand new HyperGraphDB instance will not have any such listeners defined.

getMaxCachedIncidenceSetSize

public int getMaxCachedIncidenceSetSize()

Return the configured maximum size of atom incidence sets that are kept in RAM. Small incidence sets are kept in a (usually MRU) cache, which significantly speeds up querying. This configuration options defines how small is "small". The default is 10000 - that is, incidence sets of 10000 or fewer elements are cached in RAM the first time they are accessed.

setMaxCachedIncidenceSetSize

public void setMaxCachedIncidenceSetSize(int maxCachedIncidenceSetSize)

Set the configured maximum size of atom incidence sets that are kept in RAM. Small incidence sets are kept in a (usually MRU) cache, which significantly speeds up querying. This configuration options defines how small is "small". The default is 10000 - that is, incidence sets of 10000 or fewer elements are cached in RAM the first time they are accessed.

isUseSystemAtomAttributes

public boolean isUseSystemAtomAttributes()

Return true (the default) if system-level atom attributes are stored and false otherwise. When false, this means that all system facilities depending on the availability of those attributes are not available.

getPreventDanglingAtomReferences

public boolean getPreventDanglingAtomReferences()

Return true if the system should detect and throw an exception when a possible invalid HGAtomRef occurs. This happens when when an atom is being removed, but here's a HGAtomRef.Mode.hard reference to it. The default is true.

setPreventDanglingAtomReferences

public void setPreventDanglingAtomReferences(boolean preventDanglingAtomReferences)

Specify whether the system should detect and throw an exception when a possible invalid HGAtomRef occurs. This happens when when an atom is being removed, but here's a HGAtomRef.Mode.hard reference to it. The default is true.

setUseSystemAtomAttributes

public void setUseSystemAtomAttributes(boolean useSystemAtomAttributes)

Specify whether system-level atom attributes are stored - the default is true. When false, this means that all system facilities depending on the availability of those attributes are not available.

getTypeConfiguration

public HGTypeConfiguration getTypeConfiguration()

Return the configuration bean for the type system.

getEventManager

public HGEventManager getEventManager()

Return the HGEventManager to be used by the database. The default is an instance of HGDefaultEventManager.

setEventManager

public void setEventManager(HGEventManager eventManager)

Specify the HGEventManager to be used by the database. The default is an instance of HGDefaultEventManager.

isKeepIncidentLinksOnRemoval

public boolean isKeepIncidentLinksOnRemoval()

Return true if links incident to an atom are kept in the database when that atom is being removed through the HyperGraph.remove(HGHandle) method and falseotherwise.

setKeepIncidentLinksOnRemoval

public void setKeepIncidentLinksOnRemoval(boolean keepIncidentLinksOnRemoval)

Specify whether links incident to an atom are kept in the database when that atom is being removed through the HyperGraph.remove(HGHandle) method.

getClassLoader

public ClassLoader getClassLoader()

Return the configured Java class loader for use by this HyperGraphDB instance or null if no loader was configured.

setClassLoader

public void setClassLoader(ClassLoader classLoader)

Configure a ClassLoader for this HyperGraphDB instance. The class loader is most importantly used by HGTypeSystem when loading Java classes based on the classname<->HGDB type mapping. By default, the type system will use the current thread's context class loader. Setting a custom class loader overrides this behavior.

Parameters:

classLoader -

getQueryConfiguration

public HGQueryConfiguration getQueryConfiguration()

Return the HGQueryConfiguration associated with the HyperGraph instance.

getCacheImplementation

public HGAtomCache getCacheImplementation()

Return the cache implementation configured for this HyperGraph instance.

setCacheImplementation

public void setCacheImplementation(HGAtomCache cacheImplementation)

Configure a cache implementation to be used for this HyperGraph instance.

Parameters:

cacheImplementation -