Profiler: Don’t profile NEXTDOC for ConstantScoreQuery.

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;