org.apache.jena.system

Class Txn

java.lang.Object

org.apache.jena.system.Txn

public class Txn
extends Object

Application utilities for executing code in transactions.

Nested transaction are not supported but calling inside an existing transaction, which must be compatible, (i.e. a write needs a WRITE transaction). causes the exising transaction to be used.

Constructor Summary

Constructors

Constructor and Description
Txn()

Method Summary

Modifier and Type	Method and Description
static <T extends Transactional,X> X	calc(T txn, TxnType txnType, Supplier<X> r) Execute and return a value in a transaction with the given trasnaction type.
static <T extends Transactional,X> X	calculate(T txn, Supplier<X> r) Execute in a "read" transaction that can promote to "write" and return some calculated value.
static <T extends Transactional,X> X	calculateRead(T txn, Supplier<X> r) Execute and return a value in a read transaction
static <T extends Transactional,X> X	calculateWrite(T txn, Supplier<X> r) Execute and return a value in a write transaction.
static <T extends Transactional> void	exec(T txn, TxnType txnType, Runnable r) Execute application code in a transaction with the given trasnaction type.
static <T extends Transactional> void	execute(T txn, Runnable r) Execute in a "read" transaction that can promote to "write".
static <T extends Transactional> void	executeRead(T txn, Runnable r) Execute in a read transaction
static <T extends Transactional> void	executeWrite(T txn, Runnable r) Execute the Runnable in a write transaction

Methods inherited from class java.lang.Object

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

Constructor Detail

Txn

public Txn()

Method Detail

execute

public static <T extends Transactional> void execute(T txn,
                                                     Runnable r)

Execute in a "read" transaction that can promote to "write".

Such a transaction may abort if an update is executed by another thread before this one is promoted to "write" mode. If so, the data protected by txn is unchanged.

If the application knows updates will be needed, consider using executeWrite(T, java.lang.Runnable) which starts in "write" mode.

The application code can call Transactional.promote() to attempt to change from "read" to "write"; the promote method returns a boolean indicating whether the promotion was possible or not.

calculate

public static <T extends Transactional,X> X calculate(T txn,
                                                      Supplier<X> r)

Execute in a "read" transaction that can promote to "write" and return some calculated value.

Such a transaction may abort if an update is executed by another thread before this one is promoted to "write" mode. If so, the data protected by txn is unchanged.

If the application knows updates will be needed, consider using executeWrite(T, java.lang.Runnable) which starts in "write" mode.

The application code can call Transactional.promote() to attempt to change from "read" to "write"; the promote method returns a boolean indicating whether the promotion was possible or not.

exec

public static <T extends Transactional> void exec(T txn,
                                                  TxnType txnType,
                                                  Runnable r)

Execute application code in a transaction with the given trasnaction type.

calc

public static <T extends Transactional,X> X calc(T txn,
                                                 TxnType txnType,
                                                 Supplier<X> r)

Execute and return a value in a transaction with the given trasnaction type.

executeRead

public static <T extends Transactional> void executeRead(T txn,
                                                         Runnable r)

Execute in a read transaction

calculateRead

public static <T extends Transactional,X> X calculateRead(T txn,
                                                          Supplier<X> r)

Execute and return a value in a read transaction

executeWrite

public static <T extends Transactional> void executeWrite(T txn,
                                                          Runnable r)

Execute the Runnable in a write transaction

calculateWrite

public static <T extends Transactional,X> X calculateWrite(T txn,
                                                           Supplier<X> r)

Execute and return a value in a write transaction.