org.apache.jena.sparql.core

Class DatasetGraphTrackActive

java.lang.Object

org.apache.jena.sparql.core.DatasetGraphWrapper

org.apache.jena.sparql.core.DatasetGraphTrackActive

All Implemented Interfaces:

org.apache.jena.atlas.lib.Closeable, org.apache.jena.atlas.lib.Sync, DatasetGraph, Transactional

public abstract class DatasetGraphTrackActive
extends DatasetGraphWrapper

Check the transactional state of a DatasetGraph

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.jena.sparql.core.Transactional

Transactional.Promote

Method Summary

Modifier and Type	Method and Description
void	abort() Abort a transaction - finish the transaction and undo any changes (if a "write" transaction)
void	begin(ReadWrite readWrite) 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	close() Close the dataset
void	commit() Commit a transaction - finish the transaction and make any changes permanent (if a "write" transaction)
void	end() Finish the transaction - if a write transaction and commit() has not been called, then abort
abstract boolean	isInTransaction() Say whether inside a transaction.
boolean	promote() Attempt to promote a transaction from "read" to "write" when the transaction started with a "promote" mode (READ_PROMOTE or READ_COMMITTED_PROMOTE).
boolean	promote(Transactional.Promote promoteMode) Attempt to promote a transaction from "read" mode to "write" and the transaction.

Methods inherited from class org.apache.jena.sparql.core.DatasetGraphWrapper

add, add, addGraph, begin, clear, contains, contains, containsGraph, delete, delete, deleteAny, find, find, find, findNG, getBase, getBaseForQuery, getContext, getDefaultGraph, getGraph, getLock, getUnionGraph, getWrapped, isEmpty, listGraphNodes, removeGraph, setDefaultGraph, size, supportsTransactionAbort, supportsTransactions, sync, toString, transactionMode, transactionType

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

begin

public final 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

Overrides:

begin in class DatasetGraphWrapper

begin

public final void begin(ReadWrite readWrite)

Description copied from interface: Transactional

Start either a READ or WRITE transaction.

Specified by:

begin in interface Transactional

Overrides:

begin in class DatasetGraphWrapper

promote

public final 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

Overrides:

promote in class DatasetGraphWrapper

promote

public final 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

Overrides:

promote in class DatasetGraphWrapper

commit

public final 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

Overrides:

commit in class DatasetGraphWrapper

abort

public final 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

Overrides:

abort in class DatasetGraphWrapper

end

public final 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

Overrides:

end in class DatasetGraphWrapper

isInTransaction

public abstract boolean isInTransaction()

Description copied from interface: Transactional

Say whether inside a transaction.

Specified by:

isInTransaction in interface Transactional

Overrides:

isInTransaction in class DatasetGraphWrapper

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 DatasetGraphWrapper