/** * 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(); } } }; } }