[ http://issues.apache.org/jira/browse/SOLR-39?page=all ]
Yonik Seeley resolved SOLR-39.
------------------------------
Resolution: Fixed
Assignee: Yonik Seeley
Thanks Greg, I just committed this.
> Searcher's getDocListAndSet methods do not accept flags, can cause NPE when
> writing output
> ------------------------------------------------------------------------------------------
>
> Key: SOLR-39
> URL: http://issues.apache.org/jira/browse/SOLR-39
> Project: Solr
> Issue Type: Bug
> Components: search
> Reporter: Greg Ludington
> Assigned To: Yonik Seeley
> Priority: Minor
> Attachments: SolrIndexSearcherdocListAndSet.patch
>
>
> SolrIndexSearcher's getDocListAndSet methods do not accept flags, which can,
> in some cases, cause a Null Pointer Exception to be thrown when writing the
> docListAndSet.docList as output. I came across the issue as I was
> implementing faceting, see
> http://www.nabble.com/Faceted-Browsing-Question-Discussion-tf1968854.html for
> the discussion.
> The simplest way to reproduce this is to modify DisMaxRequestHandler, by
> changing this:
> DocList results = s.getDocList(query, restrictions,
> SolrPluginUtils.getSort(req),
> req.getStart(), req.getLimit(),
> flags);
> rsp.add("search-results",results);
> to
> DocListAndSet listAndSet= s.getDocListAndSet(query, restrictions,
> SolrPluginUtils.getSort(req),
> req.getStart(), req.getLimit());
> DocList results = listAndSet.docList;
> rsp.add("search-results",results);
> The root cause appears to be that the scores[] is set to null, so then the
> DocIterator and its score() method is called, return scores[pos-1] will give
> null. When getDocListAndSet(..) is invoked, it eventually can get down to
> this private method:
> private DocSet getDocListAndSetNC(DocListAndSet out, Query query, DocSet
> filter, Sort lsort, int offset, int len, int flags) throws IOException
> In that method, scores is assigned as follows:
> scores = (flags&GET_SCORES)!=0 ? new float[nDocsReturned] : null;
> Since getDocListAndSet() does not pass flags (except for the implicit
> GET_DOCSET), scores is assigned as null, which eventually leads to the
> NullPointerException if you try to output the docList . The attached patch
> does not change the underlying mechanism of how scores is assigned, but works
> around the issue by adding overloaded getDocListAndSet() methods that take an
> additional flags parameter. After applying this patch, you can change the
> relevant bit in DisMaxRequestHandler to:
> DocListAndSet listAndSet= s.getDocListAndSet(query, restrictions,
> SolrPluginUtils.getSort(req),
> req.getStart(), req.getLimit(), flags);
> DocList results = listAndSet.docList;
> rsp.add("search-results",results);
> and you will no longer see the NullPointerException
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