org.openrdf.sail.memory

Class MemoryStore

java.lang.Object

org.openrdf.sail.helpers.SailBase

org.openrdf.sail.helpers.NotifyingSailBase

org.openrdf.sail.memory.MemoryStore

All Implemented Interfaces:

NotifyingSail, Sail

public class MemoryStore
extends NotifyingSailBase

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.

Author:

Arjohn Kampman, jeen

Field Summary

Fields

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

Fields inherited from class org.openrdf.sail.helpers.SailBase

connectionTimeOut, DEFAULT_CONNECTION_TIMEOUT, initializationLock, logger

Constructor Summary

Constructors

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

Method Summary

Methods

Modifier and Type	Method and Description
protected Statement	addStatement(Resource subj, URI pred, Value obj, Resource context, boolean explicit)
protected void	cancelSyncTask()
protected void	cancelSyncTimer()
protected void	cleanSnapshots() Removes statements from old snapshots from the main statement list and resets the snapshot to 1 for the rest of the statements.
protected void	commit()
protected <X extends Exception> CloseableIteration<MemStatement,X>	createStatementIterator(Class<X> excClass, Resource subj, URI pred, Value obj, boolean explicitOnly, int snapshot, ReadMode readMode, Resource... contexts) Creates a StatementIterator that contains the statements matching the specified pattern of subject, predicate, object, context.
protected NotifyingSailConnection	getConnectionInternal()
protected int	getCurrentSnapshot()
protected org.openrdf.sail.memory.MemNamespaceStore	getNamespaceStore()
boolean	getPersist()
protected MemStatementList	getStatements()
protected Lock	getStatementsReadLock()
long	getSyncDelay() Gets the currently configured sync delay.
protected Lock	getTransactionLock()
MemValueFactory	getValueFactory()
protected boolean	hasStatement(Resource subj, URI pred, Value obj, boolean explicitOnly, int snapshot, ReadMode readMode, Resource... contexts)
protected void	initializeInternal() Initializes this repository.
boolean	isWritable() Checks whether this Sail object is writable.
protected boolean	removeStatement(MemStatement st, boolean explicit)
protected void	rollback()
protected void	scheduleSnapshotCleanup()
protected void	scheduleSyncTask()
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()
protected int	size()
protected void	startTransaction()
void	sync() Synchronizes the contents of this repository with the data that is stored on disk.
protected void	syncWithLock() Synchronizes the contents of this repository with the data that is stored on disk.

Methods inherited from class org.openrdf.sail.helpers.NotifyingSailBase

addSailChangedListener, getConnection, notifySailChanged, removeSailChangedListener

Methods inherited from class org.openrdf.sail.helpers.SailBase

connectionClosed, debugEnabled, getDataDir, initialize, isInitialized, setDataDir, shutDown, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.openrdf.sail.Sail

getDataDir, initialize, setDataDir, shutDown

Field Detail

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 Detail

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 Detail

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)

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 SailBase

Throws:

SailException - when initialization of the store failed.

shutDownInternal

protected void shutDownInternal()
                         throws SailException

Specified by:

shutDownInternal in class SailBase

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.

getConnectionInternal

protected NotifyingSailConnection getConnectionInternal()
                                                 throws SailException

Overrides:

getConnectionInternal in class NotifyingSailBase

Throws:

SailException

getValueFactory

public MemValueFactory getValueFactory()

getNamespaceStore

protected org.openrdf.sail.memory.MemNamespaceStore getNamespaceStore()

getStatements

protected MemStatementList getStatements()

getCurrentSnapshot

protected int getCurrentSnapshot()

getStatementsReadLock

protected Lock getStatementsReadLock()
                              throws SailException

Throws:

SailException

getTransactionLock

protected Lock getTransactionLock()
                           throws SailException

Throws:

SailException

size

protected int size()

hasStatement

protected boolean hasStatement(Resource subj,
                   URI pred,
                   Value obj,
                   boolean explicitOnly,
                   int snapshot,
                   ReadMode readMode,
                   Resource... contexts)

createStatementIterator

protected <X extends Exception> CloseableIteration<MemStatement,X> createStatementIterator(Class<X> excClass,
                                                                               Resource subj,
                                                                               URI pred,
                                                                               Value obj,
                                                                               boolean explicitOnly,
                                                                               int snapshot,
                                                                               ReadMode readMode,
                                                                               Resource... contexts)

Creates a StatementIterator that contains the statements matching the specified pattern of subject, predicate, object, context. Inferred statements are excluded when explicitOnly is set to true . Statements from the null context are excluded when namedContextsOnly is set to true. The returned StatementIterator will assume the specified read mode.

addStatement

protected Statement addStatement(Resource subj,
                     URI pred,
                     Value obj,
                     Resource context,
                     boolean explicit)
                          throws SailException

Throws:

SailException

removeStatement

protected boolean removeStatement(MemStatement st,
                      boolean explicit)
                           throws SailException

Throws:

SailException

startTransaction

protected void startTransaction()
                         throws SailException

Throws:

SailException

commit

protected void commit()
               throws SailException

Throws:

SailException

rollback

protected void rollback()
                 throws SailException

Throws:

SailException

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

syncWithLock

protected void syncWithLock()
                     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. The calling code must get a read- or write lock from statementListLockManager before calling this method to prevent modifications to the statements list while the synchronization is in progress.

Throws:

SailException

cleanSnapshots

protected void cleanSnapshots()
                       throws InterruptedException

Removes statements from old snapshots from the main statement list and resets the snapshot to 1 for the rest of the statements.

Throws:

InterruptedException

scheduleSnapshotCleanup

protected void scheduleSnapshotCleanup()