Fix termStats posting usage (elastic#114644)

Author: afoucret

server/src/main/java/org/elasticsearch/script/ScriptTermStats.java

@@ -12,9 +12,8 @@
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.index.PostingsEnum;
 import org.apache.lucene.index.Term;
-import org.apache.lucene.index.TermState;
 import org.apache.lucene.index.TermStates;
-import org.apache.lucene.index.TermsEnum;
+import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.search.IndexSearcher;
 import org.elasticsearch.common.util.CachedSupplier;
 import org.elasticsearch.features.NodeFeature;
@@ -71,17 +70,15 @@ public int uniqueTermsCount() {
     public int matchedTermsCount() {
         final int docId = docIdSupplier.getAsInt();
         int matchedTerms = 0;
+        advancePostings(docId);
 
-        try {
-            for (PostingsEnum postingsEnum : postingsSupplier.get()) {
-                if (postingsEnum != null && postingsEnum.advance(docId) == docId && postingsEnum.freq() > 0) {
-                    matchedTerms++;
-                }
+        for (PostingsEnum postingsEnum : postingsSupplier.get()) {
+            if (postingsEnum != null && postingsEnum.docID() == docId) {
+                matchedTerms++;
             }
-            return matchedTerms;
-        } catch (IOException e) {
-            throw new UncheckedIOException(e);
         }
+
+        return matchedTerms;
     }
 
     /**
@@ -150,8 +147,9 @@ public StatsSummary termFreq() {
         final int docId = docIdSupplier.getAsInt();
 
         try {
+            advancePostings(docId);
             for (PostingsEnum postingsEnum : postingsSupplier.get()) {
-                if (postingsEnum == null || postingsEnum.advance(docId) != docId) {
+                if (postingsEnum == null || postingsEnum.docID() != docId) {
                     statsSummary.accept(0);
                 } else {
                     statsSummary.accept(postingsEnum.freq());
@@ -170,12 +168,13 @@ public StatsSummary termFreq() {
      * @return statistics on termPositions for the terms of the query in the current dac
      */
     public StatsSummary termPositions() {
-        try {
-            statsSummary.reset();
-            int docId = docIdSupplier.getAsInt();
+        statsSummary.reset();
+        int docId = docIdSupplier.getAsInt();
 
+        try {
+            advancePostings(docId);
             for (PostingsEnum postingsEnum : postingsSupplier.get()) {
-                if (postingsEnum == null || postingsEnum.advance(docId) != docId) {
+                if (postingsEnum == null || postingsEnum.docID() != docId) {
                     continue;
                 }
                 for (int i = 0; i < postingsEnum.freq(); i++) {
@@ -206,30 +205,26 @@ private TermStates[] loadTermContexts() {
     private PostingsEnum[] loadPostings() {
         try {
             PostingsEnum[] postings = new PostingsEnum[terms.length];
-            TermStates[] contexts = termContextsSupplier.get();
 
             for (int i = 0; i < terms.length; i++) {
-                TermStates termStates = contexts[i];
-                if (termStates.docFreq() == 0) {
-                    postings[i] = null;
-                    continue;
-                }
-
-                TermState state = termStates.get(leafReaderContext);
-                if (state == null) {
-                    postings[i] = null;
-                    continue;
-                }
-
-                TermsEnum termsEnum = leafReaderContext.reader().terms(terms[i].field()).iterator();
-                termsEnum.seekExact(terms[i].bytes(), state);
-
-                postings[i] = termsEnum.postings(null, PostingsEnum.ALL);
+                postings[i] = leafReaderContext.reader().postings(terms[i], PostingsEnum.POSITIONS);
             }
 
             return postings;
         } catch (IOException e) {
             throw new UncheckedIOException(e);
         }
     }
+
+    private void advancePostings(int targetDocId) {
+        try {
+            for (PostingsEnum posting : postingsSupplier.get()) {
+                if (posting != null && posting.docID() < targetDocId && posting.docID() != DocIdSetIterator.NO_MORE_DOCS) {
+                    posting.advance(targetDocId);
+                }
+            }
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
 }

server/src/test/java/org/elasticsearch/script/ScriptTermStatsTests.java

@@ -48,9 +48,9 @@ public void testMatchedTermsCount() throws IOException {
 
         // Partial match
         assertAllDocs(
-            Set.of(new Term("field", "foo"), new Term("field", "baz")),
+            Set.of(new Term("field", "foo"), new Term("field", "qux"), new Term("field", "baz")),
             ScriptTermStats::matchedTermsCount,
-            Map.of("doc-1", equalTo(1), "doc-2", equalTo(1), "doc-3", equalTo(0))
+            Map.of("doc-1", equalTo(2), "doc-2", equalTo(1), "doc-3", equalTo(0))
         );
 
         // Always returns 0 when no term is provided.
@@ -211,12 +211,12 @@ public void testTermFreq() throws IOException {
         // With missing terms
         {
             assertAllDocs(
-                Set.of(new Term("field", "foo"), new Term("field", "baz")),
+                Set.of(new Term("field", "foo"), new Term("field", "qux"), new Term("field", "baz")),
                 ScriptTermStats::termFreq,
                 Map.ofEntries(
-                    Map.entry("doc-1", equalTo(new StatsSummary(2, 1, 0, 1))),
-                    Map.entry("doc-2", equalTo(new StatsSummary(2, 2, 0, 2))),
-                    Map.entry("doc-3", equalTo(new StatsSummary(2, 0, 0, 0)))
+                    Map.entry("doc-1", equalTo(new StatsSummary(3, 2, 0, 1))),
+                    Map.entry("doc-2", equalTo(new StatsSummary(3, 2, 0, 2))),
+                    Map.entry("doc-3", equalTo(new StatsSummary(3, 0, 0, 0)))
                 )
             );
         }
@@ -274,10 +274,10 @@ public void testTermPositions() throws IOException {
         // With missing terms
         {
             assertAllDocs(
-                Set.of(new Term("field", "foo"), new Term("field", "baz")),
+                Set.of(new Term("field", "foo"), new Term("field", "qux"), new Term("field", "baz")),
                 ScriptTermStats::termPositions,
                 Map.ofEntries(
-                    Map.entry("doc-1", equalTo(new StatsSummary(1, 1, 1, 1))),
+                    Map.entry("doc-1", equalTo(new StatsSummary(2, 4, 1, 3))),
                     Map.entry("doc-2", equalTo(new StatsSummary(2, 3, 1, 2))),
                     Map.entry("doc-3", equalTo(new StatsSummary()))
                 )
@@ -311,7 +311,7 @@ private void withIndexSearcher(CheckedConsumer<IndexSearcher, IOException> consu
 
             Document doc = new Document();
             doc.add(new TextField("id", "doc-1", Field.Store.YES));
-            doc.add(new TextField("field", "foo bar", Field.Store.YES));
+            doc.add(new TextField("field", "foo bar qux", Field.Store.YES));
             w.addDocument(doc);
 
             doc = new Document();