Package org.axonframework.common.jpa

Class EntityManagerExecutor

java.lang.Object

org.axonframework.common.jpa.EntityManagerExecutor

All Implemented Interfaces:

MaterializationAware, TransactionalExecutor<jakarta.persistence.EntityManager>

public class EntityManagerExecutor
extends Object
implements TransactionalExecutor<jakarta.persistence.EntityManager>, MaterializationAware

A TransactionalExecutor implementation for EntityManagers.

The entity manager is obtained from the given EntityManagerProvider at most once, the first time apply(org.axonframework.common.function.ThrowingFunction<jakarta.persistence.EntityManager, R, java.lang.Exception>) is called, and reused for the remainder of this instance's lifetime. Concurrent apply(org.axonframework.common.function.ThrowingFunction<jakarta.persistence.EntityManager, R, java.lang.Exception>) calls are serialized, since a single EntityManager is not safe for concurrent use.

This executor never commits, rolls back, or closes the entity manager itself; that remains the responsibility of whoever supplied it through EntityManagerProvider. This is deliberate: an entity manager reached through this class is typically an ambient one bound to an externally-managed unit of work, whose commit, rollback, and close lifecycle is controlled by that external owner, not this executor.

Since:

5.0.2

Author:

John Hendrikx

Constructor Summary

Constructors

Constructor	Description
EntityManagerExecutor(EntityManagerProvider provider)	Creates a new instance.

Method Summary

Modifier and Type	Method	Description
<R> CompletableFuture<R>	apply(ThrowingFunction<jakarta.persistence.EntityManager,R,Exception> function)	Executes a transactional operation that returns a result.
<R> R	withMaterializationShielded(Function<Boolean,R> decision)	Runs decision, passing whether this executor already has a resource materialized, while preventing a concurrent TransactionalExecutor.apply(org.axonframework.common.function.ThrowingFunction<T, R, java.lang.Exception>) call from materializing it for the duration - so a caller can fall back to an independent executor without racing a concurrent materialization.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.axonframework.common.tx.TransactionalExecutor

accept

Constructor Details

EntityManagerExecutor

public EntityManagerExecutor(EntityManagerProvider provider)

Creates a new instance.

Parameters:

provider - An EntityManagerProvider, cannot be null.

Throws:

NullPointerException - If any argument is null.

Method Details

withMaterializationShielded

public <R> R withMaterializationShielded(Function<Boolean,R> decision)

Description copied from interface: MaterializationAware

Runs decision, passing whether this executor already has a resource materialized, while preventing a concurrent TransactionalExecutor.apply(org.axonframework.common.function.ThrowingFunction<T, R, java.lang.Exception>) call from materializing it for the duration - so a caller can fall back to an independent executor without racing a concurrent materialization.

Specified by:

withMaterializationShielded in interface MaterializationAware

Type Parameters:

R - the type of the result produced by decision

Parameters:

decision - given true if this executor already has a resource materialized, otherwise false; run shielded from a concurrent materialization, cannot be null

Returns:

the result of decision

apply

public <R> CompletableFuture<R> apply(ThrowingFunction<jakarta.persistence.EntityManager,R,Exception> function)

Description copied from interface: TransactionalExecutor

Executes a transactional operation that returns a result.

Implementations are responsible for managing the lifecycle of the provided resource, including obtaining, closing, commit and rollback.

Specified by:

apply in interface TransactionalExecutor<jakarta.persistence.EntityManager>

Type Parameters:

R - the type of the result returned by the function

Parameters:

function - a function that accepts the transactional resource of type T and produces a result of type R; cannot be null

Returns:

a CompletableFuture which when it completes contains the result of the provided function, never null