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https://issues.apache.org/jira/browse/JDO-548?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12545581
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Craig Russell commented on JDO-548:
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After looking at the details of the specification, I'd like to amend the
proposed interface to return a Set as well as to change the way the ObjectState
is passed.
The reason to return a Set is that there cannot be duplicates, and the
semantics of Set do this well.
The reason to return a Set<T> is for ease of use in case the classes contain a
common superclass. This is
The reason to take EnumSet as a parameter is that it is trivial to have the
user do it and there is no trivial way for the implementation. Since the states
parameter needs to efficiently filter results, it's most effective to use
states.contains(candidate).
Here's the proposed text for the specification (focus for now on the Java 5
version):
Set getManagedObjects();
Set getManagedObjects(EnumSet<ObjectState> states);
<T> Set<T> getManagedObjects(Class<T>... classes);
<T> Set<T>Set getManagedObjects(EnumSet<ObjectState> states, Class<T>...
classes);
These methods return a set of managed instances that pass the criteria of
states and classes. Managed instances for a specific instance of
PersistenceManager are defined as those that return the PersistenceManager
instance in response to JDOHelper.getPersistenceManager(). Instances are
returned in the set that are both in one of the life cycle states identified in
the EnumSet, and are assignable to any one or more of the Class instances in
the classes parameter, including abstract classes and interfaces whether
persistence-capable or not.
For example, this returns all managed instances of type Employee,
FullTimeEmployee, and PartTimeEmployee that are persistent new but not deleted:
Set<Employee> newEmployees =
pm.getManagedObjects(EnumSet.of(ObjectState.PERSISTENT_NEW), Employee.class);
The Set returned might be lazily instantiated by the implementation. Operations
performed after the getManagedObjects call that affect the set of instances
managed by a PersistenceManager might affect the iteration of the result of the
method call. For example, the effect of evict, makePersistent, or commit might
or might not be reflected in the iteration of the result. As long as an
Iterator on the result returns true to hasNext(), the result might change. To
guarantee stability of the result, the result can be iterated until
Iterator.hasNext() returns false.
This method can be used at any time, including during life cycle callbacks,
life cycle event notifications, and Synchronization callbacks. A new set of
managed instances is returned for each method call.
> PM.getManagedObjects() : access to the objects enlisted in a transaction
> ------------------------------------------------------------------------
>
> Key: JDO-548
> URL: https://issues.apache.org/jira/browse/JDO-548
> Project: JDO
> Issue Type: New Feature
> Components: api2, api2-legacy, specification
> Reporter: Andy Jefferson
> Fix For: JDO 2 maintenance release 1
>
> Attachments: api2-legacy.managedobjects.patch,
> api2.managedobjects.patch
>
>
> It would be desirable to provide access to the objects enlisted in the
> transaction of a PersistenceManager. It is proposed that this be via the
> following methods on javax.jdo.PersistenceManager.
> api2
> Collection getManagedObjects(); // Return all enlisted objects
> Collection getManagedObjects(ObjectState ... states); // Return enlisted
> objects in the specified states
> api2-legacy
> Collection getManagedObjects(); // Return all enlisted objects
> The return type could just as easily be Object[].
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