[jira] [Resolved] (JENA-1215) Make ResultSets closeable

["Andy Seaborne (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JENA-1215?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andy Seaborne resolved JENA-1215.
---------------------------------
       Resolution: Fixed
         Assignee: Andy Seaborne
    Fix Version/s: Jena 3.2.0

> Make ResultSets closeable
> -------------------------
>
>                 Key: JENA-1215
>                 URL: https://issues.apache.org/jira/browse/JENA-1215
>             Project: Apache Jena
>          Issue Type: Improvement
>          Components: ARQ
>    Affects Versions: Jena 3.1.1
>         Environment: any
>            Reporter: Paul Houle
>            Assignee: Andy Seaborne
>             Fix For: Jena 3.2.0
>
>
> Currently the QueryExecution has to be closed after you are done working with a ResultSet.  This means that you can't write a function that returns a ResultSet and expect the QueryExecution to be properly closed.
> This problem can be fixed like so.
> (1) Make the ResultSet interface extend ClosableIterator and probably AutoCloseable (and fall back to just adding close() in case plan A causes something awful to happen)
> (2) Put a reference to the QueryExecution (probably just a reference to any Autoclosable) into the StreamResultSet
> (3) Have the StreamResultSet close() implementations delegate to that,  or otherwise do nothing
> (4) Have the ResultSetStream close itself when it gets to the end.
> (5) Make sure close on the relevant QueryExecution element is idempotent (doesn't crash on a double close) otherwise behavior (4) followed by a later QE.close() could cause trouble
> (6) Make close() a no-op on ResultSetMem(),  there is no point in punishing users for using it or not using it.
> (7) ResultSetMem does not autoclose,  put it in the javadocs that a ResultSetRewindable does not self-close,  but a ResultSet which is not Rewindable does close when it hits the end 
> (8) Think about what exactly to do for a ResultSetPeekable which is not Rewindable so we don't get blindsided by a corner condition.
> (9) No isClosed() method on ResultSet because it would call attention to any fuzziness involved in (6)
> I volunteer to do this.



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