/**
* If there are configured {@link IndexSearcherWrapper} instances, the {@link IndexSearcher} of
* the provided engine searcher gets wrapped and a new {@link Engine.Searcher} instances is
* returned, otherwise the provided {@link Engine.Searcher} is returned.
*
* <p>This is invoked each time a {@link Engine.Searcher} is requested to do an operation. (for
* example search)
*/
public final Engine.Searcher wrap(EngineConfig engineConfig, Engine.Searcher engineSearcher)
throws IOException {
final ElasticsearchDirectoryReader elasticsearchDirectoryReader =
ElasticsearchDirectoryReader.getElasticsearchDirectoryReader(
engineSearcher.getDirectoryReader());
if (elasticsearchDirectoryReader == null) {
throw new IllegalStateException("Can't wrap non elasticsearch directory reader");
}
NonClosingReaderWrapper nonClosingReaderWrapper =
new NonClosingReaderWrapper(engineSearcher.getDirectoryReader());
DirectoryReader reader = wrap(nonClosingReaderWrapper);
if (reader != nonClosingReaderWrapper) {
if (reader.getCoreCacheKey() != elasticsearchDirectoryReader.getCoreCacheKey()) {
throw new IllegalStateException(
"wrapped directory reader doesn't delegate IndexReader#getCoreCacheKey, wrappers must override this method and delegate"
+ " to the original readers core cache key. Wrapped readers can't be used as cache keys since their are used only per request which would lead to subtle bugs");
}
if (ElasticsearchDirectoryReader.getElasticsearchDirectoryReader(reader)
!= elasticsearchDirectoryReader) {
// prevent that somebody wraps with a non-filter reader
throw new IllegalStateException(
"wrapped directory reader hides actual ElasticsearchDirectoryReader but shouldn't");
}
}
final IndexSearcher innerIndexSearcher = new IndexSearcher(reader);
innerIndexSearcher.setQueryCache(engineConfig.getQueryCache());
innerIndexSearcher.setQueryCachingPolicy(engineConfig.getQueryCachingPolicy());
innerIndexSearcher.setSimilarity(engineConfig.getSimilarity());
// TODO: Right now IndexSearcher isn't wrapper friendly, when it becomes wrapper friendly we
// should revise this extension point
// For example if IndexSearcher#rewrite() is overwritten than also
// IndexSearcher#createNormalizedWeight needs to be overwritten
// This needs to be fixed before we can allow the IndexSearcher from Engine to be wrapped
// multiple times
final IndexSearcher indexSearcher = wrap(engineConfig, innerIndexSearcher);
if (reader == nonClosingReaderWrapper && indexSearcher == innerIndexSearcher) {
return engineSearcher;
} else {
return new Engine.Searcher(engineSearcher.source(), indexSearcher) {
@Override
public void close() throws ElasticsearchException {
try {
reader().close();
// we close the reader to make sure wrappers can release resources if needed....
// our NonClosingReaderWrapper makes sure that our reader is not closed
} catch (IOException e) {
throw new ElasticsearchException("failed to close reader", e);
} finally {
engineSearcher.close();
}
}
};
}
}
