[
https://issues.apache.org/jira/browse/JDO-623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12700257#action_12700257
]
Matthew T. Adams commented on JDO-623:
--------------------------------------
I think we need an overloaded method here, cancel(Thread), and possible an
additional method, cancelAll().
In the event that a user shares a single Query instance across multiple
threads, each of which is calling execute() in parallel, there is no way for
the thread calling cancel to communicate to the implementation exactly which
thread's running query to cancel. This implies that there needs to be an
overload that takes a Thread instance: cancel(Thread).
This has implications on Query#execute(): the implementation must note which
Thread a query execution is executing on. This would allow the user to call
cancel() in the simple, more common use case of only one query execution
thread, as there would be only one execution recorded, and it would be the one
to be cancelled. However, in the more complicated use case of multiple,
concurrent executions, cancel() could either cancel all current executions, or
throw a JDOUserException indicating an ambiguous cancellation request. If we
decide that the method should throw, then another convenient method would be
cancelAll().
> Query cancel and timeout support
> --------------------------------
>
> Key: JDO-623
> URL: https://issues.apache.org/jira/browse/JDO-623
> Project: JDO
> Issue Type: New Feature
> Components: api2, tck2
> Reporter: Andy Jefferson
> Assignee: Andy Jefferson
> Fix For: JDO 2 maintenance release 3
>
> Attachments: JDO-623-mbo.patch, query_timeout.patch
>
>
> JDO doesn't have a mechanism to stop queries from overrunning. JPA2 now
> allows
> a persistence property to allow timing them out, and most JDO implementations
> have allowed this as an extension since JDO1. It would make sense for JDO
> (2.3) to have the same or a variation. I propose having the following
> Simple PMF property "javax.jdo.option.queryTimeout" to specify the number of
> millisecs (or secs) before any query is timed out. Throw a
> QueryTimeoutException (extends JDOException) when the timeout happens.
> Add methods Query.setTimeout(int), Query.getTimeout() to allow
> setting/retrieving the timeout interval on a per-query basis.
> Add method Query.cancel() to cancel any running query. If an implementation
> doesn't support cancelling of queries then it should throw a
> JDOUnsupportedOptionException. Any query execute() that is cancelled will
> throw a QueryInterruptedException (extends JDOUserException).
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
