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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.search.query;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.queries.MinDocQuery;
import org.apache.lucene.queries.SearchAfterSortedDocQuery;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.ConstantScoreQuery;
import org.apache.lucene.search.EarlyTerminatingSortingCollector;
import org.apache.lucene.search.FieldDoc;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.util.Counter;
import org.elasticsearch.action.search.SearchTask;
import org.elasticsearch.common.lucene.Lucene;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.util.concurrent.EsThreadPoolExecutor;
import org.elasticsearch.common.util.concurrent.QueueResizingEsThreadPoolExecutor;
import org.elasticsearch.search.DocValueFormat;
import org.elasticsearch.search.SearchPhase;
import org.elasticsearch.search.SearchService;
import org.elasticsearch.search.aggregations.AggregationPhase;
import org.elasticsearch.search.internal.ContextIndexSearcher;
import org.elasticsearch.search.internal.ScrollContext;
import org.elasticsearch.search.internal.SearchContext;
import org.elasticsearch.search.profile.ProfileShardResult;
import org.elasticsearch.search.profile.SearchProfileShardResults;
import org.elasticsearch.search.profile.query.InternalProfileCollector;
import org.elasticsearch.search.rescore.RescorePhase;
import org.elasticsearch.search.sort.SortAndFormats;
import org.elasticsearch.search.suggest.SuggestPhase;
import org.elasticsearch.tasks.TaskCancelledException;
import org.elasticsearch.threadpool.ThreadPool;
import java.util.LinkedList;
import java.util.function.Consumer;
import static org.elasticsearch.search.query.QueryCollectorContext.createCancellableCollectorContext;
import static org.elasticsearch.search.query.QueryCollectorContext.createEarlyTerminationCollectorContext;
import static org.elasticsearch.search.query.QueryCollectorContext.createFilteredCollectorContext;
import static org.elasticsearch.search.query.QueryCollectorContext.createMinScoreCollectorContext;
import static org.elasticsearch.search.query.QueryCollectorContext.createMultiCollectorContext;
import static org.elasticsearch.search.query.TopDocsCollectorContext.createTopDocsCollectorContext;
/**
* Query phase of a search request, used to run the query and get back from each shard information about the matching documents
* (document ids and score or sort criteria) so that matches can be reduced on the coordinating node
*/
public class QueryPhase implements SearchPhase {
private final AggregationPhase aggregationPhase;
private final SuggestPhase suggestPhase;
private RescorePhase rescorePhase;
public QueryPhase(Settings settings) {
this.aggregationPhase = new AggregationPhase();
this.suggestPhase = new SuggestPhase(settings);
this.rescorePhase = new RescorePhase(settings);
}
@Override
public void preProcess(SearchContext context) {
context.preProcess(true);
}
@Override
public void execute(SearchContext searchContext) throws QueryPhaseExecutionException {
if (searchContext.hasOnlySuggest()) {
suggestPhase.execute(searchContext);
// TODO: fix this once we can fetch docs for suggestions
searchContext.queryResult().topDocs(
new TopDocs(0, Lucene.EMPTY_SCORE_DOCS, 0),
new DocValueFormat[0]);
return;
}
// Pre-process aggregations as late as possible. In the case of a DFS_Q_T_F
// request, preProcess is called on the DFS phase phase, this is why we pre-process them
// here to make sure it happens during the QUERY phase
aggregationPhase.preProcess(searchContext);
final ContextIndexSearcher searcher = searchContext.searcher();
boolean rescore = execute(searchContext, searchContext.searcher(), searcher::setCheckCancelled);
if (rescore) { // only if we do a regular search
rescorePhase.execute(searchContext);
}
suggestPhase.execute(searchContext);
aggregationPhase.execute(searchContext);
if (searchContext.getProfilers() != null) {
ProfileShardResult shardResults = SearchProfileShardResults
.buildShardResults(searchContext.getProfilers());
searchContext.queryResult().profileResults(shardResults);
}
if (searchContext.searchProcessor() != null) {
searchContext.searchProcessor().postProcess(searchContext);
}
}
/**
* In a package-private method so that it can be tested without having to
* wire everything (mapperService, etc.)
* @return whether the rescoring phase should be executed
*/
static boolean execute(SearchContext searchContext,
final IndexSearcher searcher,
Consumer checkCancellationSetter) throws QueryPhaseExecutionException {
final IndexReader reader = searcher.getIndexReader();
QuerySearchResult queryResult = searchContext.queryResult();
queryResult.searchTimedOut(false);
try {
queryResult.from(searchContext.from());
queryResult.size(searchContext.size());
Query query = searchContext.query();
assert query == searcher.rewrite(query); // already rewritten
final ScrollContext scrollContext = searchContext.scrollContext();
if (scrollContext != null) {
if (scrollContext.totalHits == -1) {
// first round
assert scrollContext.lastEmittedDoc == null;
// there is not much that we can optimize here since we want to collect all
// documents in order to get the total number of hits
} else {
final ScoreDoc after = scrollContext.lastEmittedDoc;
if (returnsDocsInOrder(query, searchContext.sort())) {
// now this gets interesting: since we sort in index-order, we can directly
// skip to the desired doc
if (after != null) {
BooleanQuery bq = new BooleanQuery.Builder()
.add(query, BooleanClause.Occur.MUST)
.add(new MinDocQuery(after.doc + 1), BooleanClause.Occur.FILTER)
.build();
query = bq;
}
// ... and stop collecting after ${size} matches
searchContext.terminateAfter(searchContext.size());
searchContext.trackTotalHits(false);
} else if (canEarlyTerminate(reader, searchContext.sort())) {
// now this gets interesting: since the search sort is a prefix of the index sort, we can directly
// skip to the desired doc
if (after != null) {
BooleanQuery bq = new BooleanQuery.Builder()
.add(query, BooleanClause.Occur.MUST)
.add(new SearchAfterSortedDocQuery(searchContext.sort().sort, (FieldDoc) after), BooleanClause.Occur.FILTER)
.build();
query = bq;
}
searchContext.trackTotalHits(false);
}
}
}
final LinkedList collectors = new LinkedList<>();
// whether the chain contains a collector that filters documents
boolean hasFilterCollector = false;
if (searchContext.parsedPostFilter() != null) {
// add post filters before aggregations
// it will only be applied to top hits
collectors.add(createFilteredCollectorContext(searcher, searchContext.parsedPostFilter().query()));
// this collector can filter documents during the collection
hasFilterCollector = true;
}
if (searchContext.queryCollectors().isEmpty() == false) {
// plug in additional collectors, like aggregations
collectors.add(createMultiCollectorContext(searchContext.queryCollectors().values()));
}
if (searchContext.minimumScore() != null) {
// apply the minimum score after multi collector so we filter aggs as well
collectors.add(createMinScoreCollectorContext(searchContext.minimumScore()));
// this collector can filter documents during the collection
hasFilterCollector = true;
}
if (searchContext.terminateAfter() != SearchContext.DEFAULT_TERMINATE_AFTER) {
// apply terminate after after all filters collectors
collectors.add(createEarlyTerminationCollectorContext(searchContext.terminateAfter()));
// this collector can filter documents during the collection
hasFilterCollector = true;
}
boolean timeoutSet = scrollContext == null && searchContext.timeout() != null &&
searchContext.timeout().equals(SearchService.NO_TIMEOUT) == false;
final Runnable timeoutRunnable;
if (timeoutSet) {
final Counter counter = searchContext.timeEstimateCounter();
final long startTime = counter.get();
final long timeout = searchContext.timeout().millis();
final long maxTime = startTime + timeout;
timeoutRunnable = () -> {
final long time = counter.get();
if (time > maxTime) {
throw new TimeExceededException();
}
};
} else {
timeoutRunnable = null;
}
final Runnable cancellationRunnable;
if (searchContext.lowLevelCancellation()) {
SearchTask task = searchContext.getTask();
cancellationRunnable = () -> { if (task.isCancelled()) throw new TaskCancelledException("cancelled"); };
} else {
cancellationRunnable = null;
}
final Runnable checkCancelled;
if (timeoutRunnable != null && cancellationRunnable != null) {
checkCancelled = () -> { timeoutRunnable.run(); cancellationRunnable.run(); };
} else if (timeoutRunnable != null) {
checkCancelled = timeoutRunnable;
} else if (cancellationRunnable != null) {
checkCancelled = cancellationRunnable;
} else {
checkCancelled = null;
}
checkCancellationSetter.accept(checkCancelled);
// add cancellable
// this only performs segment-level cancellation, which is cheap and checked regardless of
// searchContext.lowLevelCancellation()
collectors.add(createCancellableCollectorContext(searchContext.getTask()::isCancelled));
final boolean doProfile = searchContext.getProfilers() != null;
// create the top docs collector last when the other collectors are known
final TopDocsCollectorContext topDocsFactory = createTopDocsCollectorContext(searchContext, reader, hasFilterCollector);
// add the top docs collector, the first collector context in the chain
collectors.addFirst(topDocsFactory);
final Collector queryCollector;
if (doProfile) {
InternalProfileCollector profileCollector = QueryCollectorContext.createQueryCollectorWithProfiler(collectors);
searchContext.getProfilers().getCurrentQueryProfiler().setCollector(profileCollector);
queryCollector = profileCollector;
} else {
queryCollector = QueryCollectorContext.createQueryCollector(collectors);
}
try {
searcher.search(query, queryCollector);
} catch (TimeExceededException e) {
assert timeoutSet : "TimeExceededException thrown even though timeout wasn't set";
queryResult.searchTimedOut(true);
} finally {
searchContext.clearReleasables(SearchContext.Lifetime.COLLECTION);
}
final QuerySearchResult result = searchContext.queryResult();
for (QueryCollectorContext ctx : collectors) {
ctx.postProcess(result);
}
EsThreadPoolExecutor executor = (EsThreadPoolExecutor)
searchContext.indexShard().getThreadPool().executor(ThreadPool.Names.SEARCH);
if (executor instanceof QueueResizingEsThreadPoolExecutor) {
QueueResizingEsThreadPoolExecutor rExecutor = (QueueResizingEsThreadPoolExecutor) executor;
queryResult.nodeQueueSize(rExecutor.getCurrentQueueSize());
queryResult.serviceTimeEWMA((long) rExecutor.getTaskExecutionEWMA());
}
if (searchContext.getProfilers() != null) {
ProfileShardResult shardResults = SearchProfileShardResults.buildShardResults(searchContext.getProfilers());
result.profileResults(shardResults);
}
return topDocsFactory.shouldRescore();
} catch (Exception e) {
throw new QueryPhaseExecutionException(searchContext, "Failed to execute main query", e);
}
}
/**
* Returns true if the provided query returns docs in index order (internal doc ids).
* @param query The query to execute
* @param sf The query sort
*/
static boolean returnsDocsInOrder(Query query, SortAndFormats sf) {
if (sf == null || Sort.RELEVANCE.equals(sf.sort)) {
// sort by score
// queries that return constant scores will return docs in index
// order since Lucene tie-breaks on the doc id
return query.getClass() == ConstantScoreQuery.class
|| query.getClass() == MatchAllDocsQuery.class;
} else {
return Sort.INDEXORDER.equals(sf.sort);
}
}
/**
* Returns whether collection within the provided reader can be early-terminated if it sorts
* with sortAndFormats.
**/
static boolean canEarlyTerminate(IndexReader reader, SortAndFormats sortAndFormats) {
if (sortAndFormats == null || sortAndFormats.sort == null) {
return false;
}
final Sort sort = sortAndFormats.sort;
for (LeafReaderContext ctx : reader.leaves()) {
Sort indexSort = ctx.reader().getMetaData().getSort();
if (indexSort == null || EarlyTerminatingSortingCollector.canEarlyTerminate(sort, indexSort) == false) {
return false;
}
}
return true;
}
private static class TimeExceededException extends RuntimeException {}
}
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