/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.search;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.DirectoryReader; // javadocs
import org.apache.lucene.index.FieldInvertState;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexReaderContext;
import org.apache.lucene.index.IndexWriter; // javadocs
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.MultiFields;
import org.apache.lucene.index.ReaderUtil;
import org.apache.lucene.index.StoredFieldVisitor;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermContext;
import org.apache.lucene.index.Terms;
import org.apache.lucene.search.similarities.BM25Similarity;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.store.NIOFSDirectory; // javadoc
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.ThreadInterruptedException;
/** Implements search over a single IndexReader.
*
* <p>Applications usually need only call the inherited
* {@link #search(Query,int)} method. For
* performance reasons, if your index is unchanging, you
* should share a single IndexSearcher instance across
* multiple searches instead of creating a new one
* per-search. If your index has changed and you wish to
* see the changes reflected in searching, you should
* use {@link DirectoryReader#openIfChanged(DirectoryReader)}
* to obtain a new reader and
* then create a new IndexSearcher from that. Also, for
* low-latency turnaround it's best to use a near-real-time
* reader ({@link DirectoryReader#open(IndexWriter)}).
* Once you have a new {@link IndexReader}, it's relatively
* cheap to create a new IndexSearcher from it.
*
* <a name="thread-safety"></a><p><b>NOTE</b>: <code>{@link
* IndexSearcher}</code> instances are completely
* thread safe, meaning multiple threads can call any of its
* methods, concurrently. If your application requires
* external synchronization, you should <b>not</b>
* synchronize on the <code>IndexSearcher</code> instance;
* use your own (non-Lucene) objects instead.</p>
*/
public class IndexSearcher {
/** A search-time {@link Similarity} that does not make use of scoring factors
* and may be used when scores are not needed. */
private static final Similarity NON_SCORING_SIMILARITY = new Similarity() {
@Override
public long computeNorm(FieldInvertState state) {
throw new UnsupportedOperationException("This Similarity may only be used for searching, not indexing");
}
@Override
public SimWeight computeWeight(float boost, CollectionStatistics collectionStats, TermStatistics... termStats) {
return new SimWeight() {};
}
@Override
public SimScorer simScorer(SimWeight weight, LeafReaderContext context) throws IOException {
return new SimScorer() {
@Override
public float score(int doc, float freq) {
return 0f;
}
@Override
public float computeSlopFactor(int distance) {
return 1f;
}
@Override
public float computePayloadFactor(int doc, int start, int end, BytesRef payload) {
return 1f;
}
};
}
};
private static QueryCache DEFAULT_QUERY_CACHE;
private static QueryCachingPolicy DEFAULT_CACHING_POLICY = new UsageTrackingQueryCachingPolicy();
static {
final int maxCachedQueries = 1000;
// min of 32MB or 5% of the heap size
final long maxRamBytesUsed = Math.min(1L << 25, Runtime.getRuntime().maxMemory() / 20);
DEFAULT_QUERY_CACHE = new LRUQueryCache(maxCachedQueries, maxRamBytesUsed);
}
final IndexReader reader; // package private for testing!
// NOTE: these members might change in incompatible ways
// in the next release
protected final IndexReaderContext readerContext;
protected final List<LeafReaderContext> leafContexts;
/** used with executor - each slice holds a set of leafs executed within one thread */
protected final LeafSlice[] leafSlices;
// These are only used for multi-threaded search
private final ExecutorService executor;
// the default Similarity
private static final Similarity defaultSimilarity = new BM25Similarity();
private QueryCache queryCache = DEFAULT_QUERY_CACHE;
private QueryCachingPolicy queryCachingPolicy = DEFAULT_CACHING_POLICY;
/**
* Expert: returns a default Similarity instance.
* In general, this method is only called to initialize searchers and writers.
* User code and query implementations should respect
* {@link IndexSearcher#getSimilarity(boolean)}.
* @lucene.internal
*/
public static Similarity getDefaultSimilarity() {
return defaultSimilarity;
}
/**
* Expert: Get the default {@link QueryCache} or {@code null} if the cache is disabled.
* @lucene.internal
*/
public static QueryCache getDefaultQueryCache() {
return DEFAULT_QUERY_CACHE;
}
/**
* Expert: set the default {@link QueryCache} instance.
* @lucene.internal
*/
public static void setDefaultQueryCache(QueryCache defaultQueryCache) {
DEFAULT_QUERY_CACHE = defaultQueryCache;
}
/**
* Expert: Get the default {@link QueryCachingPolicy}.
* @lucene.internal
*/
public static QueryCachingPolicy getDefaultQueryCachingPolicy() {
return DEFAULT_CACHING_POLICY;
}
/**
* Expert: set the default {@link QueryCachingPolicy} instance.
* @lucene.internal
*/
public static void setDefaultQueryCachingPolicy(QueryCachingPolicy defaultQueryCachingPolicy) {
DEFAULT_CACHING_POLICY = defaultQueryCachingPolicy;
}
/** The Similarity implementation used by this searcher. */
private Similarity similarity = defaultSimilarity;
/** Creates a searcher searching the provided index. */
public IndexSearcher(IndexReader r) {
this(r, null);
}
/** Runs searches for each segment separately, using the
* provided ExecutorService. IndexSearcher will not
* close/awaitTermination this ExecutorService on
* close; you must do so, eventually, on your own. NOTE:
* if you are using {@link NIOFSDirectory}, do not use
* the shutdownNow method of ExecutorService as this uses
* Thread.interrupt under-the-hood which can silently
* close file descriptors (see <a
* href="https://issues.apache.org/jira/browse/LUCENE-2239">LUCENE-2239</a>).
*
* @lucene.experimental */
public IndexSearcher(IndexReader r, ExecutorService executor) {
this(r.getContext(), executor);
}
/**
* Creates a searcher searching the provided top-level {@link IndexReaderContext}.
* <p>
* Given a non-<code>null</code> {@link ExecutorService} this method runs
* searches for each segment separately, using the provided ExecutorService.
* IndexSearcher will not close/awaitTermination this ExecutorService on
* close; you must do so, eventually, on your own. NOTE: if you are using
* {@link NIOFSDirectory}, do not use the shutdownNow method of
* ExecutorService as this uses Thread.interrupt under-the-hood which can
* silently close file descriptors (see <a
* href="https://issues.apache.org/jira/browse/LUCENE-2239">LUCENE-2239</a>).
*
* @see IndexReaderContext
* @see IndexReader#getContext()
* @lucene.experimental
*/
public IndexSearcher(IndexReaderContext context, ExecutorService executor) {
assert context.isTopLevel: "IndexSearcher's ReaderContext must be topLevel for reader" + context.reader();
reader = context.reader();
this.executor = executor;
this.readerContext = context;
leafContexts = context.leaves();
this.leafSlices = executor == null ? null : slices(leafContexts);
}
/**
* Creates a searcher searching the provided top-level {@link IndexReaderContext}.
*
* @see IndexReaderContext
* @see IndexReader#getContext()
* @lucene.experimental
*/
public IndexSearcher(IndexReaderContext context) {
this(context, null);
}
/**
* Set the {@link QueryCache} to use when scores are not needed.
* A value of {@code null} indicates that query matches should never be
* cached. This method should be called <b>before</b> starting using this
* {@link IndexSearcher}.
* <p>NOTE: When using a query cache, queries should not be modified after
* they have been passed to IndexSearcher.
* @see QueryCache
* @lucene.experimental
*/
public void setQueryCache(QueryCache queryCache) {
this.queryCache = queryCache;
}
/**
* Return the query cache of this {@link IndexSearcher}. This will be either
* the {@link #getDefaultQueryCache() default query cache} or the query cache
* that was last set through {@link #setQueryCache(QueryCache)}. A return
* value of {@code null} indicates that caching is disabled.
* @lucene.experimental
*/
public QueryCache getQueryCache() {
return queryCache;
}
/**
* Set the {@link QueryCachingPolicy} to use for query caching.
* This method should be called <b>before</b> starting using this
* {@link IndexSearcher}.
* @see QueryCachingPolicy
* @lucene.experimental
*/
public void setQueryCachingPolicy(QueryCachingPolicy queryCachingPolicy) {
this.queryCachingPolicy = Objects.requireNonNull(queryCachingPolicy);
}
/**
* Return the query cache of this {@link IndexSearcher}. This will be either
* the {@link #getDefaultQueryCachingPolicy() default policy} or the policy
* that was last set through {@link #setQueryCachingPolicy(QueryCachingPolicy)}.
* @lucene.experimental
*/
public QueryCachingPolicy getQueryCachingPolicy() {
return queryCachingPolicy;
}
/**
* Expert: Creates an array of leaf slices each holding a subset of the given leaves.
* Each {@link LeafSlice} is executed in a single thread. By default there
* will be one {@link LeafSlice} per leaf ({@link org.apache.lucene.index.LeafReaderContext}).
*/
protected LeafSlice[] slices(List<LeafReaderContext> leaves) {
LeafSlice[] slices = new LeafSlice[leaves.size()];
for (int i = 0; i < slices.length; i++) {
slices[i] = new LeafSlice(leaves.get(i));
}
return slices;
}
/** Return the {@link IndexReader} this searches. */
public IndexReader getIndexReader() {
return reader;
}
/**
* Sugar for <code>.getIndexReader().document(docID)</code>
* @see IndexReader#document(int)
*/
public Document doc(int docID) throws IOException {
return reader.document(docID);
}
/**
* Sugar for <code>.getIndexReader().document(docID, fieldVisitor)</code>
* @see IndexReader#document(int, StoredFieldVisitor)
*/
public void doc(int docID, StoredFieldVisitor fieldVisitor) throws IOException {
reader.document(docID, fieldVisitor);
}
/**
* Sugar for <code>.getIndexReader().document(docID, fieldsToLoad)</code>
* @see IndexReader#document(int, Set)
*/
public Document doc(int docID, Set<String> fieldsToLoad) throws IOException {
return reader.document(docID, fieldsToLoad);
}
/** Expert: Set the Similarity implementation used by this IndexSearcher.
*
*/
public void setSimilarity(Similarity similarity) {
this.similarity = similarity;
}
/** Expert: Get the {@link Similarity} to use to compute scores. When
* {@code needsScores} is {@code false}, this method will return a simple
* {@link Similarity} that does not leverage scoring factors such as norms.
* When {@code needsScores} is {@code true}, this returns the
* {@link Similarity} that has been set through {@link #setSimilarity(Similarity)}
* or the {@link #getDefaultSimilarity()} default {@link Similarity} if none
* has been set explicitly. */
public Similarity getSimilarity(boolean needsScores) {
return needsScores ? similarity : NON_SCORING_SIMILARITY;
}
/**
* Count how many documents match the given query.
*/
public int count(Query query) throws IOException {
query = rewrite(query);
while (true) {
// remove wrappers that don't matter for counts
if (query instanceof ConstantScoreQuery) {
query = ((ConstantScoreQuery) query).getQuery();
} else {
break;
}
}
// some counts can be computed in constant time
if (query instanceof MatchAllDocsQuery) {
return reader.numDocs();
} else if (query instanceof TermQuery && reader.hasDeletions() == false) {
Term term = ((TermQuery) query).getTerm();
int count = 0;
for (LeafReaderContext leaf : reader.leaves()) {
count += leaf.reader().docFreq(term);
}
return count;
}
// general case: create a collecor and count matches
final CollectorManager<TotalHitCountCollector, Integer> collectorManager = new CollectorManager<TotalHitCountCollector, Integer>() {
@Override
public TotalHitCountCollector newCollector() throws IOException {
return new TotalHitCountCollector();
}
@Override
public Integer reduce(Collection<TotalHitCountCollector> collectors) throws IOException {
int total = 0;
for (TotalHitCountCollector collector : collectors) {
total += collector.getTotalHits();
}
return total;
}
};
return search(query, collectorManager);
}
/** Finds the top <code>n</code>
* hits for <code>query</code> where all results are after a previous
* result (<code>after</code>).
* <p>
* By passing the bottom result from a previous page as <code>after</code>,
* this method can be used for efficient 'deep-paging' across potentially
* large result sets.
*
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
public TopDocs searchAfter(ScoreDoc after, Query query, int numHits) throws IOException {
final int limit = Math.max(1, reader.maxDoc());
if (after != null && after.doc >= limit) {
throw new IllegalArgumentException("after.doc exceeds the number of documents in the reader: after.doc="
+ after.doc + " limit=" + limit);
}
final int cappedNumHits = Math.min(numHits, limit);
final CollectorManager<TopScoreDocCollector, TopDocs> manager = new CollectorManager<TopScoreDocCollector, TopDocs>() {
@Override
public TopScoreDocCollector newCollector() throws IOException {
return TopScoreDocCollector.create(cappedNumHits, after);
}
@Override
public TopDocs reduce(Collection<TopScoreDocCollector> collectors) throws IOException {
final TopDocs[] topDocs = new TopDocs[collectors.size()];
int i = 0;
for (TopScoreDocCollector collector : collectors) {
topDocs[i++] = collector.topDocs();
}
return TopDocs.merge(0, cappedNumHits, topDocs, true);
}
};
return search(query, manager);
}
/** Finds the top <code>n</code>
* hits for <code>query</code>.
*
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
public TopDocs search(Query query, int n)
throws IOException {
return searchAfter(null, query, n);
}
/** Lower-level search API.
*
* <p>{@link LeafCollector#collect(int)} is called for every matching document.
*
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
public void search(Query query, Collector results)
throws IOException {
search(leafContexts, createNormalizedWeight(query, results.needsScores()), results);
}
/** Search implementation with arbitrary sorting, plus
* control over whether hit scores and max score
* should be computed. Finds
* the top <code>n</code> hits for <code>query</code>, and sorting
* the hits by the criteria in <code>sort</code>.
* If <code>doDocScores</code> is <code>true</code>
* then the score of each hit will be computed and
* returned. If <code>doMaxScore</code> is
* <code>true</code> then the maximum score over all
* collected hits will be computed.
*
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
public TopFieldDocs search(Query query, int n,
Sort sort, boolean doDocScores, boolean doMaxScore) throws IOException {
return searchAfter(null, query, n, sort, doDocScores, doMaxScore);
}
/**
* Search implementation with arbitrary sorting.
* @param query The query to search for
* @param n Return only the top n results
* @param sort The {@link org.apache.lucene.search.Sort} object
* @return The top docs, sorted according to the supplied {@link org.apache.lucene.search.Sort} instance
* @throws IOException if there is a low-level I/O error
*/
public TopFieldDocs search(Query query, int n, Sort sort) throws IOException {
return searchAfter(null, query, n, sort, false, false);
}
/** Finds the top <code>n</code>
* hits for <code>query</code> where all results are after a previous
* result (<code>after</code>).
* <p>
* By passing the bottom result from a previous page as <code>after</code>,
* this method can be used for efficient 'deep-paging' across potentially
* large result sets.
*
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
public TopDocs searchAfter(ScoreDoc after, Query query, int n, Sort sort) throws IOException {
return searchAfter(after, query, n, sort, false, false);
}
/** Finds the top <code>n</code>
* hits for <code>query</code> where all results are after a previous
* result (<code>after</code>), allowing control over
* whether hit scores and max score should be computed.
* <p>
* By passing the bottom result from a previous page as <code>after</code>,
* this method can be used for efficient 'deep-paging' across potentially
* large result sets. If <code>doDocScores</code> is <code>true</code>
* then the score of each hit will be computed and
* returned. If <code>doMaxScore</code> is
* <code>true</code> then the maximum score over all
* collected hits will be computed.
*
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
public TopFieldDocs searchAfter(ScoreDoc after, Query query, int numHits, Sort sort,
boolean doDocScores, boolean doMaxScore) throws IOException {
if (after != null && !(after instanceof FieldDoc)) {
// TODO: if we fix type safety of TopFieldDocs we can
// remove this
throw new IllegalArgumentException("after must be a FieldDoc; got " + after);
}
return searchAfter((FieldDoc) after, query, numHits, sort, doDocScores, doMaxScore);
}
private TopFieldDocs searchAfter(FieldDoc after, Query query, int numHits, Sort sort,
boolean doDocScores, boolean doMaxScore) throws IOException {
final int limit = Math.max(1, reader.maxDoc());
if (after != null && after.doc >= limit) {
throw new IllegalArgumentException("after.doc exceeds the number of documents in the reader: after.doc="
+ after.doc + " limit=" + limit);
}
final int cappedNumHits = Math.min(numHits, limit);
final CollectorManager<TopFieldCollector, TopFieldDocs> manager = new CollectorManager<TopFieldCollector, TopFieldDocs>() {
@Override
public TopFieldCollector newCollector() throws IOException {
final boolean fillFields = true;
return TopFieldCollector.create(sort, cappedNumHits, after, fillFields, doDocScores, doMaxScore);
}
@Override
public TopFieldDocs reduce(Collection<TopFieldCollector> collectors) throws IOException {
final TopFieldDocs[] topDocs = new TopFieldDocs[collectors.size()];
int i = 0;
for (TopFieldCollector collector : collectors) {
topDocs[i++] = collector.topDocs();
}
return TopDocs.merge(sort, 0, cappedNumHits, topDocs, true);
}
};
return search(query, manager);
}
/**
* Lower-level search API.
* Search all leaves using the given {@link CollectorManager}. In contrast
* to {@link #search(Query, Collector)}, this method will use the searcher's
* {@link ExecutorService} in order to parallelize execution of the collection
* on the configured {@link #leafSlices}.
* @see CollectorManager
* @lucene.experimental
*/
public <C extends Collector, T> T search(Query query, CollectorManager<C, T> collectorManager) throws IOException {
if (executor == null) {
final C collector = collectorManager.newCollector();
search(query, collector);
return collectorManager.reduce(Collections.singletonList(collector));
} else {
final List<C> collectors = new ArrayList<>(leafSlices.length);
boolean needsScores = false;
for (int i = 0; i < leafSlices.length; ++i) {
final C collector = collectorManager.newCollector();
collectors.add(collector);
needsScores |= collector.needsScores();
}
final Weight weight = createNormalizedWeight(query, needsScores);
final List<Future<C>> topDocsFutures = new ArrayList<>(leafSlices.length);
for (int i = 0; i < leafSlices.length; ++i) {
final LeafReaderContext[] leaves = leafSlices[i].leaves;
final C collector = collectors.get(i);
topDocsFutures.add(executor.submit(new Callable<C>() {
@Override
public C call() throws Exception {
search(Arrays.asList(leaves), weight, collector);
return collector;
}
}));
}
final List<C> collectedCollectors = new ArrayList<>();
for (Future<C> future : topDocsFutures) {
try {
collectedCollectors.add(future.get());
} catch (InterruptedException e) {
throw new ThreadInterruptedException(e);
} catch (ExecutionException e) {
throw new RuntimeException(e);
}
}
return collectorManager.reduce(collectors);
}
}
/**
* Lower-level search API.
*
* <p>
* {@link LeafCollector#collect(int)} is called for every document. <br>
*
* <p>
* NOTE: this method executes the searches on all given leaves exclusively.
* To search across all the searchers leaves use {@link #leafContexts}.
*
* @param leaves
* the searchers leaves to execute the searches on
* @param weight
* to match documents
* @param collector
* to receive hits
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
protected void search(List<LeafReaderContext> leaves, Weight weight, Collector collector)
throws IOException {
// TODO: should we make this
// threaded...? the Collector could be sync'd?
// always use single thread:
for (LeafReaderContext ctx : leaves) { // search each subreader
final LeafCollector leafCollector;
try {
leafCollector = collector.getLeafCollector(ctx);
} catch (CollectionTerminatedException e) {
// there is no doc of interest in this reader context
// continue with the following leaf
continue;
}
BulkScorer scorer = weight.bulkScorer(ctx);
if (scorer != null) {
try {
scorer.score(leafCollector, ctx.reader().getLiveDocs());
} catch (CollectionTerminatedException e) {
// collection was terminated prematurely
// continue with the following leaf
}
}
}
}
/** Expert: called to re-write queries into primitive queries.
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
public Query rewrite(Query original) throws IOException {
Query query = original;
for (Query rewrittenQuery = query.rewrite(reader); rewrittenQuery != query;
rewrittenQuery = query.rewrite(reader)) {
query = rewrittenQuery;
}
return query;
}
/** Returns an Explanation that describes how <code>doc</code> scored against
* <code>query</code>.
*
* <p>This is intended to be used in developing Similarity implementations,
* and, for good performance, should not be displayed with every hit.
* Computing an explanation is as expensive as executing the query over the
* entire index.
*/
public Explanation explain(Query query, int doc) throws IOException {
return explain(createNormalizedWeight(query, true), doc);
}
/** Expert: low-level implementation method
* Returns an Explanation that describes how <code>doc</code> scored against
* <code>weight</code>.
*
* <p>This is intended to be used in developing Similarity implementations,
* and, for good performance, should not be displayed with every hit.
* Computing an explanation is as expensive as executing the query over the
* entire index.
* <p>Applications should call {@link IndexSearcher#explain(Query, int)}.
* @throws BooleanQuery.TooManyClauses If a query would exceed
* {@link BooleanQuery#getMaxClauseCount()} clauses.
*/
protected Explanation explain(Weight weight, int doc) throws IOException {
int n = ReaderUtil.subIndex(doc, leafContexts);
final LeafReaderContext ctx = leafContexts.get(n);
int deBasedDoc = doc - ctx.docBase;
final Bits liveDocs = ctx.reader().getLiveDocs();
if (liveDocs != null && liveDocs.get(deBasedDoc) == false) {
return Explanation.noMatch("Document " + doc + " is deleted");
}
return weight.explain(ctx, deBasedDoc);
}
/**
* Creates a normalized weight for a top-level {@link Query}.
* The query is rewritten by this method and {@link Query#createWeight} called,
* afterwards the {@link Weight} is normalized. The returned {@code Weight}
* can then directly be used to get a {@link Scorer}.
* @lucene.internal
*/
public Weight createNormalizedWeight(Query query, boolean needsScores) throws IOException {
query = rewrite(query);
return createWeight(query, needsScores, 1f);
}
/**
* Creates a {@link Weight} for the given query, potentially adding caching
* if possible and configured.
* @lucene.experimental
*/
public Weight createWeight(Query query, boolean needsScores, float boost) throws IOException {
final QueryCache queryCache = this.queryCache;
Weight weight = query.createWeight(this, needsScores, boost);
if (needsScores == false && queryCache != null) {
weight = queryCache.doCache(weight, queryCachingPolicy);
}
return weight;
}
/**
* Returns this searchers the top-level {@link IndexReaderContext}.
* @see IndexReader#getContext()
*/
/* sugar for #getReader().getTopReaderContext() */
public IndexReaderContext getTopReaderContext() {
return readerContext;
}
/**
* A class holding a subset of the {@link IndexSearcher}s leaf contexts to be
* executed within a single thread.
*
* @lucene.experimental
*/
public static class LeafSlice {
final LeafReaderContext[] leaves;
public LeafSlice(LeafReaderContext... leaves) {
this.leaves = leaves;
}
}
@Override
public String toString() {
return "IndexSearcher(" + reader + "; executor=" + executor + ")";
}
/**
* Returns {@link TermStatistics} for a term.
*
* This can be overridden for example, to return a term's statistics
* across a distributed collection.
* @lucene.experimental
*/
public TermStatistics termStatistics(Term term, TermContext context) throws IOException {
return new TermStatistics(term.bytes(), context.docFreq(), context.totalTermFreq());
}
/**
* Returns {@link CollectionStatistics} for a field.
*
* This can be overridden for example, to return a field's statistics
* across a distributed collection.
* @lucene.experimental
*/
public CollectionStatistics collectionStatistics(String field) throws IOException {
final int docCount;
final long sumTotalTermFreq;
final long sumDocFreq;
assert field != null;
Terms terms = MultiFields.getTerms(reader, field);
if (terms == null) {
docCount = 0;
sumTotalTermFreq = 0;
sumDocFreq = 0;
} else {
docCount = terms.getDocCount();
sumTotalTermFreq = terms.getSumTotalTermFreq();
sumDocFreq = terms.getSumDocFreq();
}
return new CollectionStatistics(field, reader.maxDoc(), docCount, sumTotalTermFreq, sumDocFreq);
}
}