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Reference documentation covers async Hibernate/JPA bootstrap options

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Issue: SPR-17189
This commit is contained in:
Juergen Hoeller
2018-08-16 17:30:44 +02:00
parent 31c7807ac9
commit 50b6f9da1d
1 changed files with 59 additions and 7 deletions
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src/docs/asciidoc/data-access.adoc
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@@ -311,8 +311,8 @@ The above definition of the `dataSource` bean uses the `<jndi-lookup/>` tag from
====
You can also use Hibernate local transactions easily, as shown in the following
examples. In this case, you need to define a Hibernate `LocalSessionFactoryBean`, which
your application code will use to obtain Hibernate `Session` instances.
examples. In this case, you need to define a Hibernate `LocalSessionFactoryBean`,
which your application code will use to obtain Hibernate `Session` instances.
The `DataSource` bean definition will be similar to the local JDBC example shown
previously and thus is not shown in the following example.
@@ -5116,8 +5116,8 @@ chapter will then cover the other ORM technologies, showing briefer examples the
====
As of Spring Framework 5.0, Spring requires Hibernate ORM 4.3 or later for JPA support
and even Hibernate ORM 5.0+ for programming against the native Hibernate Session API.
Note that the Hibernate team does not maintain any versions prior to 5.0 anymore and
is likely to focus on 5.2+ exclusively soon.
Note that the Hibernate team does not maintain any versions prior to 5.1 anymore and
is likely to focus on 5.3+ exclusively soon.
====
@@ -5175,8 +5175,25 @@ configuration:
----
You can also access a JNDI-located `SessionFactory`, using Spring's
`JndiObjectFactoryBean` / `<jee:jndi-lookup>` to retrieve and expose it. However, that
is typically not common outside of an EJB context.
`JndiObjectFactoryBean` / `<jee:jndi-lookup>` to retrieve and expose it.
However, that is typically not common outside of an EJB context.
[NOTE]
====
Spring also provides a `LocalSessionFactoryBuilder` variant, seamlessly integrating
with `@Bean` style configuration and programmatic setup (no `FactoryBean` involved).
Both `LocalSessionFactoryBean` and `LocalSessionFactoryBuilder` support background
bootstrapping, with Hibernate initialization running in parallel to the application
bootstrap thread on a given bootstrap executor (e.g. a `SimpleAsyncTaskExecutor`).
On `LocalSessionFactoryBean`, this is available through the "bootstrapExecutor"
property; on the programmatic `LocalSessionFactoryBuilder`, there is an overloaded
`buildSessionFactory` method which takes a bootstrap executor argument.
As of Spring Framework 5.1, such a native Hibernate setup can also expose a JPA
`EntityManagerFactory` for standard JPA interaction next to native Hibernate access.
See <<orm-jpa-hibernate,Native Hibernate setup for JPA>> for details.
====
[[orm-hibernate-straight]]
@@ -5781,7 +5798,7 @@ This is important especially when the hosting applications rely on different JPA
implementations because the JPA transformers are applied only at class loader level and
thus are isolated from each other.
[[orm-jpa-multiple]]
[[orm-jpa-setup-multiple]]
===== Dealing with multiple persistence units
For applications that rely on multiple persistence units locations, stored in various
@@ -5825,6 +5842,30 @@ affect __all__ hosted units, or programmatically, through the
`PersistenceUnitManager` is specified, one is created and used internally by
`LocalContainerEntityManagerFactoryBean`.
[[orm-jpa-setup-background]]
===== Background bootstrapping
`LocalContainerEntityManagerFactoryBean` supports background bootstrapping through
the `bootstrapExecutor` property:
[source,xml,indent=0]
[subs="verbatim,quotes"]
----
<bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="bootstrapExecutor">
<bean class="org.springframework.core.task.SimpleAsyncTaskExecutor"/>
</property>
</bean>
----
The actual JPA provider bootstrapping will be handed off to the specified executor then,
running in parallel to the application bootstrap thread. The exposed `EntityManagerFactory`
proxy can be injected into other application components and is even able to respond
`EntityManagerFactoryInfo` configuration inspection. However, once the actual JPA provider
is being accessed by other components, e.g. calling `createEntityManager`, those calls
will block until the background bootstrapping has completed. In particular, when using
Spring Data JPA, make sure to set up deferred bootstrapping for its repositories as well.
[[orm-jpa-dao]]
==== Implementing DAOs based on JPA: EntityManagerFactory and EntityManager
@@ -6087,6 +6128,17 @@ as well as stronger optimizations for read-only transactions. Last but not least
native Hibernate setup can also be expressed through `LocalSessionFactoryBuilder`,
seamlessly integrating with `@Bean` style configuration (no `FactoryBean` involved).
[NOTE]
====
`LocalSessionFactoryBean` and `LocalSessionFactoryBuilder` support background
bootstrapping, just like the JPA `LocalContainerEntityManagerFactoryBean`.
See <<orm-jpa-setup-background,Background bootstrapping>> for an introduction.
On `LocalSessionFactoryBean`, this is available through the "bootstrapExecutor"
property; on the programmatic `LocalSessionFactoryBuilder`, there is an overloaded
`buildSessionFactory` method which takes a bootstrap executor argument.
====