Profiler: Don’t profile NEXTDOC for ConstantScoreQuery. (#33196)

* Profiler: Don’t profile NEXTDOC for ConstantScoreQuery. A ConstantScore query will return the iterator of its inner query. However, when profiling, the constant score query is wrapped separately from its inner query, which distorts the times emitted by the profiler. Return the iterator directly in such a case. Closes #23430

Author: iverase

server/src/main/java/org/elasticsearch/search/profile/AbstractProfileBreakdown.java

@@ -49,6 +49,10 @@ public Timer getTimer(T timing) {
  return timings[timing.ordinal()];
  }
 
+ public void setTimer(T timing, Timer timer) {
+ timings[timing.ordinal()] = timer;
+ }
+
  /** Convert this record to a map from timingType to times. */
  public Map<String, Long> toTimingMap() {
  Map<String, Long> map = new HashMap<>();

server/src/main/java/org/elasticsearch/search/profile/query/ProfileScorer.java

@@ -19,7 +19,9 @@
 
 package org.elasticsearch.search.profile.query;
 
+import org.apache.lucene.search.ConstantScoreQuery;
 import org.apache.lucene.search.DocIdSetIterator;
+import org.apache.lucene.search.Scorable;
 import org.apache.lucene.search.Scorer;
 import org.apache.lucene.search.TwoPhaseIterator;
 import org.apache.lucene.search.Weight;
@@ -36,7 +38,10 @@ final class ProfileScorer extends Scorer {
 
  private final Scorer scorer;
  private ProfileWeight profileWeight;
+
  private final Timer scoreTimer, nextDocTimer, advanceTimer, matchTimer, shallowAdvanceTimer, computeMaxScoreTimer;
+ private final boolean isConstantScoreQuery;
+
 
  ProfileScorer(ProfileWeight w, Scorer scorer, QueryProfileBreakdown profile) throws IOException {
  super(w);
@@ -48,6 +53,26 @@ final class ProfileScorer extends Scorer {
  matchTimer = profile.getTimer(QueryTimingType.MATCH);
  shallowAdvanceTimer = profile.getTimer(QueryTimingType.SHALLOW_ADVANCE);
  computeMaxScoreTimer = profile.getTimer(QueryTimingType.COMPUTE_MAX_SCORE);
+ ProfileScorer profileScorer = null;
+ if (w.getQuery() instanceof ConstantScoreQuery && scorer instanceof ProfileScorer) {
+ //Case when we have a totalHits query and it is not cached
+ profileScorer = (ProfileScorer) scorer;
+ } else if (w.getQuery() instanceof ConstantScoreQuery && scorer.getChildren().size() == 1) {
+ //Case when we have a top N query. If the scorer has no children, it is because it is cached
+ //and in that case we do not do any special treatment
+ Scorable childScorer = scorer.getChildren().iterator().next().child;
+ if (childScorer instanceof ProfileScorer) {
+ profileScorer = (ProfileScorer) childScorer;
+ }
+ }
+ if (profileScorer != null) {
+ isConstantScoreQuery = true;
+ profile.setTimer(QueryTimingType.NEXT_DOC, profileScorer.nextDocTimer);
+ profile.setTimer(QueryTimingType.ADVANCE, profileScorer.advanceTimer);
+ profile.setTimer(QueryTimingType.MATCH, profileScorer.matchTimer);
+ } else {
+ isConstantScoreQuery = false;
+ }
  }
 
  @Override
@@ -77,6 +102,9 @@ public Collection<ChildScorable> getChildren() throws IOException {
 
  @Override
  public DocIdSetIterator iterator() {
+ if (isConstantScoreQuery) {
+ return scorer.iterator();
+ }
  final DocIdSetIterator in = scorer.iterator();
  return new DocIdSetIterator() {
 
@@ -114,6 +142,9 @@ public long cost() {
 
  @Override
  public TwoPhaseIterator twoPhaseIterator() {
+ if (isConstantScoreQuery) {
+ return scorer.twoPhaseIterator();
+ }
  final TwoPhaseIterator in = scorer.twoPhaseIterator();
  if (in == null) {
  return null;