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OPENJPA-1932: Documentation update: Extract entity locking to a new section and add missing lock modes defined in JPA 2.0. 

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@1095186 13f79535-47bb-0310-9956-ffa450edef68
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Milosz Tylenda 2011-04-19 20:07:05 +00:00
parent c2b3e11a78
commit 77b7ced1d5
1 changed files with 107 additions and 47 deletions
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154
openjpa-project/src/doc/manual/jpa_overview_em.xml
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@ -494,53 +494,6 @@ whose <link linkend="jpa_overview_meta_cascade">cascades</link> include
</para> </para>
</listitem> </listitem>
</itemizedlist> </itemizedlist>
<programlisting>
public void lock(Object entity, LockModeType mode);
</programlisting>
<para>
<indexterm>
<primary>
EntityManager
</primary>
<secondary>
lock
</secondary>
</indexterm>
<indexterm>
<primary>
locking
</primary>
<seealso>
EntityManager
</seealso>
</indexterm>
This method locks the given entity using the named mode. The
<ulink url="http://download.oracle.com/javaee/6/api/javax/persistence/LockModeType.html">
<classname>javax.persistence.LockModeType</classname></ulink> enum defines two
modes:
</para>
<itemizedlist>
<listitem>
<para>
<literal>READ</literal>: Other transactions may concurrently read the object,
but cannot concurrently update it.
</para>
</listitem>
<listitem>
<para>
<literal>WRITE</literal>: Other transactions cannot concurrently read or write
the object. When a transaction is committed that holds WRITE locks on any
entities, those entities will have their version incremented even if the entities
themselves did not change in the transaction.
</para>
</listitem>
</itemizedlist>
<note>
<para>
OpenJPA has additional APIs for controlling object locking. See
<xref linkend="ref_guide_locking"/> in the Reference Guide for details.
</para>
</note>
<para> <para>
The following diagram illustrates the lifecycle of an entity with respect to the The following diagram illustrates the lifecycle of an entity with respect to the
APIs presented in this section. APIs presented in this section.
@ -1025,6 +978,113 @@ language. For relational databases, this is the Structured Query Language (SQL).
native query support. native query support.
</para> </para>
</section> </section>
<section id="jpa_overview_em_locking">
<title>
Entity Locking
</title>
<indexterm zone="jpa_overview_em_locking">
<primary>
EntityManager
</primary>
<secondary>
locking
</secondary>
</indexterm>
<programlisting>
public void lock(Object entity, LockModeType mode);
</programlisting>
<para>
<indexterm>
<primary>
EntityManager
</primary>
<secondary>
lock
</secondary>
</indexterm>
<indexterm>
<primary>
locking
</primary>
<seealso>
EntityManager
</seealso>
</indexterm>
This method locks the given entity using the named mode. The
<ulink url="http://download.oracle.com/javaee/6/api/javax/persistence/LockModeType.html">
<classname>javax.persistence.LockModeType</classname></ulink> enum defines eight
modes:
</para>
<itemizedlist>
<listitem>
<para>
<literal>OPTIMISTIC</literal>: Optimistic locking.
</para>
</listitem>
<listitem>
<para>
<literal>OPTIMISTIC_FORCE_INCREMENT</literal>: Optimistic locking.
When a transaction is committed, the entity's version column
will be incremented even if the entity's state did not change in the transaction.
</para>
</listitem>
<listitem>
<para>
<literal>PESSIMISTIC_READ</literal>: Pessimistic locking. Other transactions
may concurrently read the entity, but cannot concurrently update it.
</para>
</listitem>
<listitem>
<para>
<literal>PESSIMISTIC_WRITE</literal>: Pessimistic locking. Other transactions
cannot concurrently read or write the entity.
</para>
</listitem>
<listitem>
<para>
<literal>PESSIMISTIC_FORCE_INCREMENT</literal>: Pessimistic locking. Other transactions
cannot concurrently read or write the entity.
When a transaction is committed, the entity's version column
will be incremented even if the entity's state did not change in the transaction.
</para>
</listitem>
<listitem>
<para>
<literal>READ</literal>: A synonym for <literal>OPTIMISTIC</literal>.
</para>
</listitem>
<listitem>
<para>
<literal>WRITE</literal>: A synonym for <literal>OPTIMISTIC_FORCE_INCREMENT</literal>.
</para>
</listitem>
<listitem>
<para>
<literal>NONE</literal>: No locking is performed.
</para>
</listitem>
</itemizedlist>
<note>
<itemizedlist>
<listitem>
<para>
OpenJPA differentiates between <literal>PESSIMISTIC_READ</literal> and
<literal>PESSIMISTIC_WRITE</literal> lock modes only with DB2 databases.
While running with other databases, there is no distinction between these
two modes because
<literal>PESSIMISTIC_READ</literal> lock mode
is upgraded to <literal>PESSIMISTIC_WRITE</literal>.
</para>
</listitem>
<listitem>
<para>
OpenJPA has additional APIs for controlling entity locking. See
<xref linkend="ref_guide_locking"/> in the Reference Guide for details.
</para>
</listitem>
</itemizedlist>
</note>
</section>
<section id="jpa_overview_em_properties"> <section id="jpa_overview_em_properties">
<title> <title>
Retrieving Properties Information Retrieving Properties Information