Package org.eclipse.rdf4j.sail.memory

Class MemoryStore

java.lang.Object

org.eclipse.rdf4j.sail.helpers.AbstractSail

org.eclipse.rdf4j.sail.helpers.AbstractNotifyingSail

org.eclipse.rdf4j.sail.memory.MemoryStore

All Implemented Interfaces:

FederatedServiceResolverClient, NotifyingSail, Sail

public class MemoryStore
extends AbstractNotifyingSail
implements FederatedServiceResolverClient

An implementation of the Sail interface that stores its data in main memory and that can use a file for persistent storage. This Sail implementation supports single, isolated transactions. This means that changes to the data are not visible until a transaction is committed and that concurrent transactions are not possible. When another transaction is active, calls to startTransaction() will block until the active transaction is committed or rolled back.

The MemoryStore is designed for datasets with fewer than 100,000 triples. The MemoryStore uses hash tables, and when these hash tables fill up it copies the values to larger hash tables. This can cause strain on the garbage collector due to lots of memory being allocated and freed.

Author:

Arjohn Kampman, jeen

Field Summary

Fields

Modifier and Type	Field	Description
protected static final String	DATA_FILE_NAME
protected static final String	SYNC_FILE_NAME

Fields inherited from class org.eclipse.rdf4j.sail.helpers.AbstractSail

connectionTimeOut, DEFAULT_CONNECTION_TIMEOUT, DEFAULT_ITERATION_SYNC_THRESHOLD, initializationLock

Constructor Summary

Constructors

Constructor	Description
MemoryStore()	Creates a new MemoryStore.
MemoryStore(File dataDir)	Creates a new persistent MemoryStore.

Method Summary

Modifier and Type	Method	Description
protected void	cancelSyncTask()
protected void	cancelSyncTimer()
protected NotifyingSailConnection	getConnectionInternal()	Returns a store-specific SailConnection object.
EvaluationStrategyFactory	getEvaluationStrategyFactory()
FederatedServiceResolver	getFederatedServiceResolver()	Gets the FederatedServiceResolver used by this client.
boolean	getPersist()
long	getSyncDelay()	Gets the currently configured sync delay.
ValueFactory	getValueFactory()	Gets a ValueFactory object that can be used to create IRI-, blank node-, literal- and statement objects.
protected void	initializeInternal()	Initializes this repository.
boolean	isWritable()	Checks whether this Sail object is writable.
void	notifySailChanged(SailChangedEvent event)	Notifies all registered SailChangedListener's of changes to the contents of this Sail.
protected void	scheduleSyncTask()
void	setEvaluationStrategyFactory(EvaluationStrategyFactory factory)	Sets the EvaluationStrategy to use.
void	setFederatedServiceResolver(FederatedServiceResolver resolver)	Overrides the FederatedServiceResolver used by this instance, but the given resolver is not shutDown when this instance is.
void	setPersist(boolean persist)
void	setSyncDelay(long syncDelay)	Sets the time (in milliseconds) to wait after a transaction was commited before writing the changed data to file.
protected void	shutDownInternal()	Do store-specific operations to ensure proper shutdown of the store.
void	sync()	Synchronizes the contents of this repository with the data that is stored on disk.

Methods inherited from class org.eclipse.rdf4j.sail.helpers.AbstractNotifyingSail

addSailChangedListener, getConnection, removeSailChangedListener

Methods inherited from class org.eclipse.rdf4j.sail.helpers.AbstractSail

addSupportedIsolationLevel, connectionClosed, debugEnabled, getDataDir, getDefaultIsolationLevel, getDefaultQueryEvaluationMode, getIterationCacheSyncThreshold, getSupportedIsolationLevels, init, isInitialized, isTrackResultSize, removeSupportedIsolationLevel, setConnectionTimeOut, setDataDir, setDefaultIsolationLevel, setDefaultQueryEvaluationMode, setIterationCacheSyncThreshold, setSupportedIsolationLevels, setSupportedIsolationLevels, setTrackResultSize, shutDown, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.rdf4j.sail.Sail

getCollectionFactory, getDataDir, getDefaultIsolationLevel, getSupportedIsolationLevels, init, setDataDir, shutDown

Field Details

DATA_FILE_NAME

protected static final String DATA_FILE_NAME

See Also:

• Constant Field Values

SYNC_FILE_NAME

protected static final String SYNC_FILE_NAME

See Also:

• Constant Field Values

Constructor Details

MemoryStore

public MemoryStore()

Creates a new MemoryStore.

MemoryStore

public MemoryStore(File dataDir)

Creates a new persistent MemoryStore. If the specified data directory contains an existing store, its contents will be restored upon initialization.

Parameters:

dataDir - the data directory to be used for persistence.

Method Details

setPersist

public void setPersist(boolean persist)

getPersist

public boolean getPersist()

setSyncDelay

public void setSyncDelay(long syncDelay)

Sets the time (in milliseconds) to wait after a transaction was commited before writing the changed data to file. Setting this variable to 0 will force a file sync immediately after each commit. A negative value will deactivate file synchronization until the Sail is shut down. A positive value will postpone the synchronization for at least that amount of milliseconds. If in the meantime a new transaction is started, the file synchronization will be rescheduled to wait for another syncDelay ms. This way, bursts of transaction events can be combined in one file sync.

The default value for this parameter is 0 (immediate synchronization).

Parameters:

syncDelay - The sync delay in milliseconds.

getSyncDelay

public long getSyncDelay()

Gets the currently configured sync delay.

Returns:

syncDelay The sync delay in milliseconds.

See Also:

• setSyncDelay(long)

getEvaluationStrategyFactory

public EvaluationStrategyFactory getEvaluationStrategyFactory()

Returns:

Returns the EvaluationStrategy.

setEvaluationStrategyFactory

public void setEvaluationStrategyFactory(EvaluationStrategyFactory factory)

Sets the EvaluationStrategy to use.

getFederatedServiceResolver

public FederatedServiceResolver getFederatedServiceResolver()

Description copied from interface: FederatedServiceResolverClient

Gets the FederatedServiceResolver used by this client.

Specified by:

getFederatedServiceResolver in interface FederatedServiceResolverClient

Returns:

Returns the SERVICE resolver.

setFederatedServiceResolver

public void setFederatedServiceResolver(FederatedServiceResolver resolver)

Overrides the FederatedServiceResolver used by this instance, but the given resolver is not shutDown when this instance is.

Specified by:

setFederatedServiceResolver in interface FederatedServiceResolverClient

Parameters:

resolver - The SERVICE resolver to set.

initializeInternal

protected void initializeInternal()
                           throws SailException

Initializes this repository. If a persistence file is defined for the store, the contents will be restored.

Overrides:

initializeInternal in class AbstractSail

Throws:

SailException - when initialization of the store failed.

shutDownInternal

protected void shutDownInternal()
                         throws SailException

Description copied from class: AbstractSail

Do store-specific operations to ensure proper shutdown of the store.

Specified by:

shutDownInternal in class AbstractSail

Throws:

SailException

isWritable

public boolean isWritable()

Checks whether this Sail object is writable. A MemoryStore is not writable if a read-only data file is used.

Specified by:

isWritable in interface Sail

getConnectionInternal

protected NotifyingSailConnection getConnectionInternal()
                                                 throws SailException

Description copied from class: AbstractSail

Returns a store-specific SailConnection object.

Specified by:

getConnectionInternal in class AbstractNotifyingSail

Returns:

A connection to the store.

Throws:

SailException

getValueFactory

public ValueFactory getValueFactory()

Description copied from interface: Sail

Gets a ValueFactory object that can be used to create IRI-, blank node-, literal- and statement objects.

Specified by:

getValueFactory in interface Sail

Returns:

a ValueFactory object for this Sail object.

notifySailChanged

public void notifySailChanged(SailChangedEvent event)

Description copied from class: AbstractNotifyingSail

Notifies all registered SailChangedListener's of changes to the contents of this Sail.

Overrides:

notifySailChanged in class AbstractNotifyingSail

scheduleSyncTask

protected void scheduleSyncTask()
                         throws SailException

Throws:

SailException

cancelSyncTask

protected void cancelSyncTask()

cancelSyncTimer

protected void cancelSyncTimer()

sync

public void sync()
          throws SailException

Synchronizes the contents of this repository with the data that is stored on disk. Data will only be written when the contents of the repository and data in the file are out of sync.

Throws:

SailException