Example usage for org.apache.lucene.index LeafReader getReaderCacheHelper

Introduction

In this page you can find the example usage for org.apache.lucene.index LeafReader getReaderCacheHelper.

Prototype

public abstract CacheHelper getReaderCacheHelper();

Source Link

Document

Optional method: Return a CacheHelper that can be used to cache based on the content of this reader.

Usage

From source file:org.elasticsearch.xpack.core.security.authz.accesscontrol.DocumentSubsetReader.java

License:Open Source License

/**
 * Like {@link #computeNumDocs} but caches results.
 *///from w  w w .  j ava2 s  .  co m
private static int getNumDocs(LeafReader reader, Query roleQuery, BitSet roleQueryBits)
        throws IOException, ExecutionException {
    IndexReader.CacheHelper cacheHelper = reader.getReaderCacheHelper(); // this one takes deletes into account
    if (cacheHelper == null) {
        throw new IllegalStateException("Reader " + reader + " does not support caching");
    }
    final boolean[] added = new boolean[] { false };
    Cache<Query, Integer> perReaderCache = NUM_DOCS_CACHE.computeIfAbsent(cacheHelper.getKey(), key -> {
        added[0] = true;
        return CacheBuilder.<Query, Integer>builder()
                // Not configurable, this limit only exists so that if a role query is updated
                // then we won't risk OOME because of old role queries that are not used anymore
                .setMaximumWeight(1000).weigher((k, v) -> 1) // just count
                .build();
    });
    if (added[0]) {
        IndexReader.ClosedListener closedListener = NUM_DOCS_CACHE::remove;
        try {
            cacheHelper.addClosedListener(closedListener);
        } catch (AlreadyClosedException e) {
            closedListener.onClose(cacheHelper.getKey());
            throw e;
        }
    }
    return perReaderCache.computeIfAbsent(roleQuery, q -> computeNumDocs(reader, roleQuery, roleQueryBits));
}

---