Class 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.

Arjohn Kampman, jeen
  • Field Details

  • 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.
      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).

      syncDelay - The sync delay in milliseconds.
    • getSyncDelay

      public long getSyncDelay()
      Gets the currently configured sync delay.
      syncDelay The sync delay in milliseconds.
      See Also:
    • getEvaluationStrategyFactory

      public EvaluationStrategyFactory getEvaluationStrategyFactory()
      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 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
      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.
      initializeInternal in class AbstractSail
      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
    • 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
      A connection to the store.
    • 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
      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.
      notifySailChanged in class AbstractNotifyingSail
    • scheduleSyncTask

      protected void scheduleSyncTask() 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.