Module org.apache.jena.arq
Package org.apache.jena.system.buffering

Class BufferingDatasetGraph

java.lang.Object
org.apache.jena.sparql.core.DatasetGraphBase
org.apache.jena.sparql.core.DatasetGraphBaseFind
org.apache.jena.sparql.core.DatasetGraphTriplesQuads
org.apache.jena.system.buffering.BufferingDatasetGraph
All Implemented Interfaces:
org.apache.jena.atlas.lib.Closeable, DatasetGraph, Transactional, BufferingCtl, DatasetGraphBuffering
public class BufferingDatasetGraph extends DatasetGraphTriplesQuads implements DatasetGraphBuffering
BufferingDatasetGraph - stores operations as adds/deletes of "triples" (default graph) and "quads" (named graphs)

  • Constructor Details

    • BufferingDatasetGraph

      public BufferingDatasetGraph(DatasetGraph dsg)
      Create a BufferingDatasetGraph which buffers 1 transaction.

    • BufferingDatasetGraph

      public BufferingDatasetGraph(DatasetGraph dsg, int txnBuffering)
      Create a BufferingDatasetGraph which buffers upto txnBuffering transactions.

  • Method Details

    • getAddedTriples

      public Set<org.apache.jena.graph.Triple> getAddedTriples()

    • getDeletedTriples

      public Set<org.apache.jena.graph.Triple> getDeletedTriples()

    • getAddedQuads

      public Set<Quad> getAddedQuads()

    • getDeletedQuads

      public Set<Quad> getDeletedQuads()

    • base

      public DatasetGraph base()

    • accessState

      public org.apache.jena.system.buffering.BufferingDatasetGraph.AccessState accessState()

    • flush

      public void flush()
      Send the changes to the underlying store and end the buffering session.
      Specified by:
      flush in interface BufferingCtl

    • reset

      public void reset()
      Description copied from interface: BufferingCtl
      Remove any changes that are buffered.
      Specified by:
      reset in interface BufferingCtl

    • flushToDB

      public void flushToDB()
      Send the changes to the underlying store, drop the buffered changes that have been flushed, but do not end the buffering session.

    • state

      public String state()

    • contains

      public boolean contains(Quad quad)
      Description copied from interface: DatasetGraph
      Test whether the dataset contains a quad (including default graph)- may include wildcards, Node.ANY or null
      Specified by:
      contains in interface DatasetGraph
      Overrides:
      contains in class DatasetGraphBase

    • contains

      public boolean contains(org.apache.jena.graph.Node g, org.apache.jena.graph.Node s, org.apache.jena.graph.Node p, org.apache.jena.graph.Node o)
      Description copied from interface: DatasetGraph
      Test whether the dataset (including default graph) contains a quad - may include wildcards, Node.ANY or null
      Specified by:
      contains in interface DatasetGraph
      Overrides:
      contains in class DatasetGraphBase

    • getDefaultGraph

      public org.apache.jena.graph.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

    • getGraph

      public org.apache.jena.graph.Graph getGraph(org.apache.jena.graph.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

    • getUnionGraph

      public org.apache.jena.graph.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

    • listGraphNodes

      public Iterator<org.apache.jena.graph.Node> listGraphNodes()
      Description copied from interface: DatasetGraph
      Iterate over all names of named graphs
      Specified by:
      listGraphNodes in interface DatasetGraph

    • prefixes

      public PrefixMap prefixes()
      Description copied from interface: DatasetGraph
      Prefixes for this DatasetGraph
      Specified by:
      prefixes in interface DatasetGraph

    • begin

      public void begin()
      Description copied from interface: Transactional
      Start a transaction which is READ mode and which will switch to WRITE if an update is attempted but only if no intermediate transaction has performed an update.

      See Transactional.begin(TxnType) for more details an options.

      May not be implemented. See Transactional.begin(ReadWrite) is guaranteed to be provided.

      Specified by:
      begin in interface Transactional

    • 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

    • begin

      public void begin(ReadWrite mode)
      Description copied from interface: Transactional
      Start either a READ or WRITE transaction.
      Specified by:
      begin 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

    • promote

      public boolean promote(Transactional.Promote mode)
      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

    • 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

    • isInTransaction

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

    • 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

    • 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

    • 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