Class DatasetGraphWrapper

    • Constructor Detail

      • DatasetGraphWrapper

        public DatasetGraphWrapper​(DatasetGraph dsg)
        Create a operations wrapper around dsg. The Context of the wrapper is the context of the dsg.
      • DatasetGraphWrapper

        public DatasetGraphWrapper​(DatasetGraph dsg,
                                   Context context)
        Create a operations wrapper around dsg with context.
    • Method Detail

      • getWrapped

        public final DatasetGraph getWrapped()
        Return the DatasetGraph being wrapped.
      • getBase

        public final DatasetGraph getBase()
        Recursively unwrap a DatasetGraphWrapper.

        Note 1: Some use of DatasetGraphWrapper does not use the wrapped dataset stored in this object.

        Note 2: TDB datasets require a transaction to unwrap.

        Returns:
        the first found DatasetGraph that is not an instance of DatasetGraphWrapper
      • unwrap

        public static DatasetGraph unwrap​(DatasetGraph dsg)
        Unwrap a DatasetGraph to find the base DatasetGraph. Calls getBase() if the argument is a DatasetGraphWrapper.

        Note 1: Some use of DatasetGraphWrapper does not use the wrapped dataset stored in this object.

        Note 2: TDB datasets require a transaction to unwrap.

      • containsGraph

        public boolean containsGraph​(Node graphNode)
        Description copied from interface: DatasetGraph
        Does the DatasetGraph contain a specific named graph? 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 and this returns true always.
        Specified by:
        containsGraph in interface DatasetGraph
        Returns:
        boolean
      • 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
      • 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
      • 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
      • setDefaultGraph

        public void setDefaultGraph​(Graph g)
        Description copied from interface: DatasetGraph
        Set the default graph. Set the active graph if it was null. 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
      • getLock

        public Lock getLock()
        Description copied from interface: DatasetGraph
        Return a lock for the dataset to help with concurrency control
        Specified by:
        getLock in interface DatasetGraph
        See Also:
        Lock
      • listGraphNodes

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

        public boolean isEmpty()
        Description copied from interface: DatasetGraph
        Test whether the dataset is empty
        Specified by:
        isEmpty in interface DatasetGraph
      • find

        public java.util.Iterator<Quad> find()
        Description copied from interface: DatasetGraph
        Iterate over all quads in the dataset graph
        Specified by:
        find in interface DatasetGraph
      • 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
      • contains

        public boolean contains​(Node g,
                                Node s,
                                Node p,
                                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
      • 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
      • 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
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object
      • sync

        public void sync()
        Specified by:
        sync in interface org.apache.jena.atlas.lib.Sync
      • 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
      • begin

        public void begin​(TxnType type)
        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()
        Description copied from interface: Transactional
        Attempt to promote a transaction from "read" to "write" when the transaction started with a "promote" mode (READ_PROMOTE or READ_COMMITTED_PROMOTE).

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

        A READ_COMMITTED_PROMOTE can always be promoted, but the call may need to wait.

        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. Any further calls to promote() will also return false.

        This method returns false if there is an attempt to promote a "READ" transaction.

        Specified by:
        promote in interface Transactional
      • promote

        public boolean promote​(Transactional.Promote type)
        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
      • 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