org.neo4j.helpers

Class TransactionTemplate

java.lang.Object

org.neo4j.helpers.TransactionTemplate

public class TransactionTemplate
extends Object

Neo4j transaction template that automates the retry-on-exception logic. It uses the builder pattern for configuration, with copy-semantics, so you can iteratively build up instances for different scenarios.

First instantiate and configure the template using the fluent API methods, and then invoke execute which will begin/commit transactions in a loop for the specified number of times.

By default all exceptions (except Errors and TransactionTerminatedException) cause a retry, and the monitor does nothing, but these can be overridden with custom behavior. A bit more narrow and typical exception to retry on is TransientFailureException, which aims to represent exceptions that are most likely to succeed after a retry.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	TransactionTemplate.Monitor

Constructor Summary

Constructors

Constructor and Description
TransactionTemplate() Creates a template for performing transactions with retry logic.
TransactionTemplate(org.neo4j.graphdb.GraphDatabaseService gds, TransactionTemplate.Monitor monitor, int retries, long backoff, Predicate<Throwable> retryPredicate) Create a template for performing transaction with retry logic.

Method Summary

Modifier and Type	Method and Description
TransactionTemplate	backoff(long backoff, TimeUnit unit)
void	execute(Consumer<org.neo4j.graphdb.Transaction> txConsumer) Executes a transaction with retry logic.
<T> T	execute(Function<org.neo4j.graphdb.Transaction,T> txFunction) Executes a transaction with retry logic returning a result.
TransactionTemplate	monitor(TransactionTemplate.Monitor monitor)
TransactionTemplate	retries(int retries)
TransactionTemplate	retryOn(Predicate<Throwable> retryPredicate)
TransactionTemplate	with(org.neo4j.graphdb.GraphDatabaseService gds)

Methods inherited from class java.lang.Object

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

Constructor Detail

TransactionTemplate

public TransactionTemplate()

Creates a template for performing transactions with retry logic.

Default exceptions to retry on is everything except Error and TransactionTerminatedException.

TransactionTemplate

public TransactionTemplate(org.neo4j.graphdb.GraphDatabaseService gds,
                           TransactionTemplate.Monitor monitor,
                           int retries,
                           long backoff,
                           Predicate<Throwable> retryPredicate)

Create a template for performing transaction with retry logic.

Parameters:

gds - graph database to execute on.

monitor - a monitor that can react to events.

retries - number of retries to try before failing.

backoff - milliseconds to wait between each retry.

retryPredicate - what Throwable's to retry on.

Method Detail

with

public TransactionTemplate with(org.neo4j.graphdb.GraphDatabaseService gds)

retries

public TransactionTemplate retries(int retries)

backoff

public TransactionTemplate backoff(long backoff,
                                   TimeUnit unit)

monitor

public TransactionTemplate monitor(TransactionTemplate.Monitor monitor)

retryOn

public TransactionTemplate retryOn(Predicate<Throwable> retryPredicate)

execute

public void execute(Consumer<org.neo4j.graphdb.Transaction> txConsumer)

Executes a transaction with retry logic.

Parameters:

txConsumer - a consumer that takes transactions.

Throws:

org.neo4j.graphdb.TransactionFailureException - if an error occurs other than those specified in retryOn(Predicate) or if the retry count was exceeded.

execute

public <T> T execute(Function<org.neo4j.graphdb.Transaction,T> txFunction)
              throws org.neo4j.graphdb.TransactionFailureException

Executes a transaction with retry logic returning a result.

Type Parameters:

T - type of the result.

Parameters:

txFunction - function taking a transaction and producing a result.

Returns:

the result with type T.

Throws:

org.neo4j.graphdb.TransactionFailureException - if an error occurs other than those specified in retryOn(Predicate) or if the retry count was exceeded.