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https://issues.apache.org/jira/browse/GEODE-9602?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alberto Gomez reassigned GEODE-9602:
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Assignee: Alberto Gomez
> QueryObserver improvements
> --------------------------
>
> Key: GEODE-9602
> URL: https://issues.apache.org/jira/browse/GEODE-9602
> Project: Geode
> Issue Type: Bug
> Components: querying
> Reporter: Alberto Gomez
> Assignee: Alberto Gomez
> Priority: Major
>
> The QueryObserver interface allows to create classes that would be notified
> about query events.
> The way to set a QueryObserver is by means of the QueryObserverHolder class,
> that is able to hold a single instance of a QueryObserver.
> This mechanism currently has two problems:
> * The QueryObserverHolder class is not thread-safe. The observer instance to
> be returned by the getInstance() class could return an undefined value.
> * Given that the observer is retrieved via the
> QueryObserverHolder::getInstance() method at different points of the query
> execution, it is possible that if several queries with different observers
> are run in parallel, the observers for the queries will be changed in the
> middle of the query execution with unexpected results for the queries.
> In order to solve the above problems, the following is proposed:
> * Make the QueryObserverHolder class thread-safe.
> * Allow for having an observer per query. A simple way to allow this is to
> set the observer in the query context when the query is started. That way,
> several queries could be run in parallel, each with its own observer.
> Apart from the above, it's been observed that there are no QueryObserver
> before/after iteration evaluation 'callbacks' invoked when the query is using
> indexes.
> It is also proposed to add these before/after IterationEvaluation callbacks
> so that they are called also when the query is using indexes.
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