Class DatasetGraphInMemory

All Implemented Interfaces:
org.apache.jena.atlas.lib.Closeable, DatasetGraph, Transactional

public class DatasetGraphInMemory extends DatasetGraphTriplesQuads implements Transactional
A DatasetGraph backed by an QuadTable. By default, this is a HexTable designed for high-speed in-memory operation.
  • Constructor Details

    • DatasetGraphInMemory

      public DatasetGraphInMemory()
      Default constructor.
    • DatasetGraphInMemory

      public DatasetGraphInMemory(QuadTable i, TripleTable t)
      Parameters:
      i - a table in which to store quads
      t - a table in which to store triples
  • Method Details

    • isInTransaction

      public boolean isInTransaction()
      Description copied from interface: Transactional
      Say whether inside a transaction.
      Specified by:
      isInTransaction in interface Transactional
    • transactionMode

      public ReadWrite transactionMode()
      Description copied from interface: Transactional
      Return the current mode of the transaction - "read" or "write". If the caller is not in a transaction, this method returns null.
      Specified by:
      transactionMode in interface Transactional
      Returns:
      the current mode of the transaction in progress
    • transactionType

      public TxnType transactionType()
      Description copied from interface: Transactional
      Return the transaction type used in begin(TxnType). If the caller is not in a transaction, this method returns null.
      Specified by:
      transactionType in interface Transactional
    • supportsTransactions

      public boolean supportsTransactions()
      Description copied from interface: DatasetGraph
      A DatasetGraph supports transactions if it provides Transactional.begin()/ Transactional.commit()/Transactional.end(). The core storage DatasetGraphs provide fully serialized transactions. A DatasetGraph that provides functionality across independent systems can not provide such strong guarantees. For example, it may use MRSW locking and some isolation control. Specifically, it would not necessarily provide Transactional.abort().

      See DatasetGraph.supportsTransactionAbort() for Transactional.abort(). In addition, check details of a specific implementation.

      Specified by:
      supportsTransactions in interface DatasetGraph
    • supportsTransactionAbort

      public boolean supportsTransactionAbort()
      Description copied from interface: DatasetGraph
      Declare whether Transactional.abort() is supported. This goes along with clearing up after exceptions inside application transaction code.
      Specified by:
      supportsTransactionAbort in interface DatasetGraph
    • begin

      public void begin(TxnType txnType)
      Description copied from interface: Transactional
      Start a transaction.
      READ or WRITE transactions start in that state and do not change for the lifetime of the transaction.
      • WRITE: this guarantees a WRITE will complete if commit() is called. The same as begin(ReadWrite.WRITE).
      • READ: the transaction can not promote to WRITE,ensuring read-only access to the data. The same as begin(ReadWrite.READ).
      • READ_PROMOTE: the transaction will go from "read" to "write" if an update is attempted and if the dataset has not been changed by another write transaction. See also Transactional.promote().
      • READ_COMMITTED_PROMOTE: Use this with care. The promotion will succeed but changes from other transactions become visible.
      Read committed: at the point transaction attempts promotion from "read" to "write", the system checks if the dataset has change since the transaction started (called begin). If READ_PROMOTE, the dataset must not have changed; if READ_COMMITTED_PROMOTE any intermediate changes are visible but the application can not assume any data it has read in the transaction is the same as it was at the point the transaction started.

      This operation is optional and some implementations may throw a JenaTransactionException exception for some or all TxnType values.

      See Transactional.begin(ReadWrite) for a form that is required of implementations.

      Specified by:
      begin in interface Transactional
    • promote

      public boolean promote(Transactional.Promote promoteMode)
      Description copied from interface: Transactional
      Attempt to promote a transaction from "read" mode to "write" and the transaction. This method allows the form of promotion to be specified. The transaction must not have been started with READ, which is read-only.

      An argument of READ_PROMOTE treats the promotion as if the transaction was started with READ_PROMOTE (any other writer commiting since the transaction started blocks promotion) and READ_COMMITTED_PROMOTE treats the promotion as if the transaction was started with READ_COMMITTED_PROMOTE (intemediate writer commits become visible).

      Returns "true" if the transaction is in write mode after the call. The method always succeeds of the transaction is already "write".

      This method returns true if a READ_PROMOTE or READ_COMMITTED_PROMOTE is promoted.

      This method returns false if a READ_PROMOTE can't be promoted - the transaction is still valid and in "read" mode.

      This method throws an exception if there is an attempt to promote a READ transaction.

      Specified by:
      promote in interface Transactional
    • commit

      public void commit()
      Description copied from interface: Transactional
      Commit a transaction - finish the transaction and make any changes permanent (if a "write" transaction)
      Specified by:
      commit in interface Transactional
    • abort

      public void abort()
      Description copied from interface: Transactional
      Abort a transaction - finish the transaction and undo any changes (if a "write" transaction)
      Specified by:
      abort in interface Transactional
    • close

      public void close()
      Description copied from interface: DatasetGraph
      Close the dataset
      Specified by:
      close in interface org.apache.jena.atlas.lib.Closeable
      Specified by:
      close in interface DatasetGraph
      Overrides:
      close in class DatasetGraphBase
    • end

      public void end()
      Description copied from interface: Transactional
      Finish the transaction - if a write transaction and commit() has not been called, then abort
      Specified by:
      end in interface Transactional
    • listGraphNodes

      public Iterator<Node> listGraphNodes()
      Description copied from interface: DatasetGraph
      Iterate over all names of named graphs
      Specified by:
      listGraphNodes in interface DatasetGraph
    • setDefaultGraph

      public void setDefaultGraph(Graph g)
      Description copied from interface: DatasetGraph
      Set the default graph. This replaces the contents default graph, not merge data into it. Do not assume that the same object is returned by DatasetGraph.getDefaultGraph()
      Specified by:
      setDefaultGraph in interface DatasetGraph
      Overrides:
      setDefaultGraph in class DatasetGraphTriplesQuads
    • getGraph

      public Graph getGraph(Node graphNode)
      Description copied from interface: DatasetGraph
      Get the graph named by graphNode : returns null when there is no such graph. NB Whether a dataset contains a graph if there are no triples is not defined - see the specific implementation. Some datasets are "open" - they have all graphs even if no triples.
      Specified by:
      getGraph in interface DatasetGraph
      Specified by:
      getGraph in class DatasetGraphBase
    • getDefaultGraph

      public Graph getDefaultGraph()
      Description copied from interface: DatasetGraph
      Get the default graph as a Jena Graph
      Specified by:
      getDefaultGraph in interface DatasetGraph
      Specified by:
      getDefaultGraph in class DatasetGraphBase
    • getUnionGraph

      public Graph getUnionGraph()
      Description copied from interface: DatasetGraph
      Return a Graph that is the union of all named graphs in this dataset. This union graph is read-only (its prefix mapping in the current JVM may be changed but that may not persist).
      Specified by:
      getUnionGraph in interface DatasetGraph
      Overrides:
      getUnionGraph in class DatasetGraphBase
    • addGraph

      public void addGraph(Node graphName, Graph graph)
      Description copied from interface: DatasetGraph
      Add the given graph to the dataset. Replaces any existing data for the named graph; to add data, get the graph and add triples to it, or add quads to the dataset. Do not assume that the same Java object is returned by DatasetGraph.getGraph(org.apache.jena.graph.Node)
      Specified by:
      addGraph in interface DatasetGraph
      Overrides:
      addGraph in class DatasetGraphTriplesQuads
    • removeGraph

      public void removeGraph(Node graphName)
      Description copied from interface: DatasetGraph
      Remove all data associated with the named graph. This will include prefixes associated with the graph.
      Specified by:
      removeGraph in interface DatasetGraph
      Overrides:
      removeGraph in class DatasetGraphTriplesQuads
    • prefixes

      public PrefixMap prefixes()
      Description copied from interface: DatasetGraph
      Prefixes for this DatasetGraph
      Specified by:
      prefixes in interface DatasetGraph
      Returns:
      the prefixes in use in this dataset
    • size

      public long size()
      Description copied from interface: DatasetGraph
      Get the size (number of named graphs) - may be -1 for unknown
      Specified by:
      size in interface DatasetGraph
      Overrides:
      size in class DatasetGraphBase
    • clear

      public void clear()
      Description copied from interface: DatasetGraph
      Remove everything - remove all named graphs, clear the default graph
      Specified by:
      clear in interface DatasetGraph
      Overrides:
      clear in class DatasetGraphBase