public class DatasetGraphMap extends DatasetGraphTriplesQuads
DatasetGraph as an extensible set of graphs.
Subclasses need to manage any implicit graph creation.
This implementation provides copy-in, copy-out for DatasetGraphTriplesQuads.addGraph(org.apache.jena.graph.Node, org.apache.jena.graph.Graph).
See DatasetGraphMapLink for a DatasetGraph
that holds graphs as provided.
DatasetGraphMapLinkTransactional.Promote| Constructor and Description |
|---|
DatasetGraphMap()
DatasetGraphMap defaulting to storage in memory.
|
DatasetGraphMap(DatasetGraphFactory.GraphMaker graphMaker)
DatasetGraphMap with a specific policy for graph creation.
|
| Modifier and Type | Method and Description |
|---|---|
void |
abort()
Abort a transaction - finish the transaction and undo any changes (if a "write" transaction)
|
void |
begin()
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.
|
void |
begin(ReadWrite mode)
Start either a READ or WRITE transaction.
|
void |
begin(TxnType txnType)
Start a transaction.
READ or WRITE transactions start in that state and do not change for the lifetime of the transaction. |
void |
commit()
Commit a transaction - finish the transaction and make any changes permanent (if a "write" transaction)
|
boolean |
containsGraph(Node graphNode)
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.
|
void |
end()
Finish the transaction - if a write transaction and commit() has not been called, then abort
|
Graph |
getDefaultGraph()
Get the default graph as a Jena Graph
|
Graph |
getGraph(Node graphNode)
Get the graph named by graphNode : returns null when there is no such graph.
|
boolean |
isInTransaction()
Say whether inside a transaction.
|
Iterator<Node> |
listGraphNodes()
Iterate over all names of named graphs
|
boolean |
promote(Transactional.Promote txnType)
Attempt to promote a transaction from "read" mode to "write" and the transaction.
|
long |
size()
Get the size (number of named graphs) - may be -1 for unknown
|
boolean |
supportsTransactionAbort()
Declare whether
Transactional.abort() is supported. |
boolean |
supportsTransactions()
A
DatasetGraph supports transactions if it provides Transactional.begin()/
Transactional.commit()/Transactional.end(). |
ReadWrite |
transactionMode()
Return the current mode of the transaction - "read" or "write".
|
TxnType |
transactionType()
Return the transaction type used in
begin(TxnType). |
add, add, addGraph, delete, delete, removeGraph, setDefaultGraphfind, findInUnionGraph, findNG, findQuadsInUnionGraphclear, close, contains, contains, deleteAny, deleteAny, find, find, getContext, getLock, getUnionGraph, isEmpty, toStringequals, getClass, hashCode, notify, notifyAll, wait, wait, waitpromotepublic DatasetGraphMap()
public DatasetGraphMap(DatasetGraphFactory.GraphMaker graphMaker)
public void begin()
Transactional
See Transactional.begin(TxnType) for more details an options.
May not be implemented. See Transactional.begin(ReadWrite) is guaranteed to be provided.
public void begin(TxnType txnType)
TransactionalWRITE: 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.
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.
public void begin(ReadWrite mode)
Transactionalpublic boolean promote(Transactional.Promote txnType)
TransactionalREAD, 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.
public void commit()
Transactionalpublic void abort()
Transactionalpublic boolean isInTransaction()
Transactionalpublic void end()
Transactionalpublic ReadWrite transactionMode()
Transactionalpublic TxnType transactionType()
Transactionalbegin(TxnType).
If the caller is not in a transaction, this method returns null.public boolean supportsTransactions()
DatasetGraphDatasetGraph 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.
public boolean supportsTransactionAbort()
DatasetGraphTransactional.abort() is supported.
This goes along with clearing up after exceptions inside application transaction code.public Iterator<Node> listGraphNodes()
DatasetGraphpublic boolean containsGraph(Node graphNode)
DatasetGraphcontainsGraph in interface DatasetGraphcontainsGraph in class DatasetGraphBasepublic Graph getDefaultGraph()
DatasetGraphgetDefaultGraph in interface DatasetGraphgetDefaultGraph in class DatasetGraphBasepublic Graph getGraph(Node graphNode)
DatasetGraphgetGraph in interface DatasetGraphgetGraph in class DatasetGraphBasepublic long size()
DatasetGraphsize in interface DatasetGraphsize in class DatasetGraphBaseLicenced under the Apache License, Version 2.0