Empty intervals needs to start in position -1 (#89962) (#89977)

If a match interval query ends up with no tokens after analysis, we
return an IntervalsSource that produces an empty interval iterator. This
empty iterator previously always reported its current doc id as
NO_MORE_DOCS. However, unpositioned DocIdSetIterators should
report their doc id as -1, so this broke the API contract, which could lead
to exceptions when an empty interval query was combined in a conjunction.
This commit fixes the empty interval implementation so that it returns -1
when unpositioned.

Fixes #89789

Author: romseygeek

docs/changelog/89962.yaml

@@ -0,0 +1,6 @@
+pr: 89962
+summary: Empty intervals needs to start in position -1
+area: Search
+type: bug
+issues:
+ - 89789

server/src/internalClusterTest/java/org/elasticsearch/search/query/IntervalQueriesIT.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.search.query;
+
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.Tokenizer;
+import org.apache.lucene.analysis.core.KeywordTokenizer;
+import org.elasticsearch.action.search.SearchResponse;
+import org.elasticsearch.index.analysis.AnalyzerProvider;
+import org.elasticsearch.index.analysis.AnalyzerScope;
+import org.elasticsearch.index.query.IntervalQueryBuilder;
+import org.elasticsearch.index.query.IntervalsSourceProvider;
+import org.elasticsearch.indices.analysis.AnalysisModule;
+import org.elasticsearch.plugins.AnalysisPlugin;
+import org.elasticsearch.plugins.Plugin;
+import org.elasticsearch.test.ESIntegTestCase;
+import org.elasticsearch.test.InternalSettingsPlugin;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Map;
+
+import static java.util.Collections.singletonMap;
+import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
+
+public class IntervalQueriesIT extends ESIntegTestCase {
+
+    @Override
+    protected Collection<Class<? extends Plugin>> nodePlugins() {
+        return Arrays.asList(InternalSettingsPlugin.class, MockAnalysisPlugin.class);
+    }
+
+    public void testEmptyIntervalsWithNestedMappings() throws InterruptedException {
+        assertAcked(prepareCreate("nested").setMapping("""
+            { "_doc" : {
+                "properties" : {
+                    "empty_text" : { "type" : "text", "analyzer" : "empty" },
+                    "text" : { "type" : "text" },
+                    "nested" : { "type" : "nested", "properties" : { "nt" : { "type" : "text" } } }
+                }
+            }}
+            """));
+
+        indexRandom(
+            true,
+            client().prepareIndex("nested").setId("1").setSource("text", "the quick brown fox jumps"),
+            client().prepareIndex("nested").setId("2").setSource("text", "quick brown"),
+            client().prepareIndex("nested").setId("3").setSource("text", "quick")
+        );
+
+        SearchResponse resp = client().prepareSearch("nested")
+            .setQuery(
+                new IntervalQueryBuilder("empty_text", new IntervalsSourceProvider.Match("an empty query", 0, true, null, null, null))
+            )
+            .get();
+        assertEquals(0, resp.getFailedShards());
+    }
+
+    private static class EmptyAnalyzer extends Analyzer {
+
+        @Override
+        protected TokenStreamComponents createComponents(String fieldName) {
+            Tokenizer source = new KeywordTokenizer();
+            TokenStream sink = new TokenStream() {
+                @Override
+                public boolean incrementToken() throws IOException {
+                    return false;
+                }
+            };
+            return new TokenStreamComponents(source, sink);
+        }
+    }
+
+    public static class MockAnalysisPlugin extends Plugin implements AnalysisPlugin {
+
+        @Override
+        public Map<String, AnalysisModule.AnalysisProvider<AnalyzerProvider<? extends Analyzer>>> getAnalyzers() {
+            return singletonMap("empty", (indexSettings, environment, name, settings) -> new AnalyzerProvider<>() {
+                @Override
+                public String name() {
+                    return "empty";
+                }
+
+                @Override
+                public AnalyzerScope scope() {
+                    return AnalyzerScope.GLOBAL;
+                }
+
+                @Override
+                public Analyzer get() {
+                    return new EmptyAnalyzer();
+                }
+            });
+        }
+    }
+}

server/src/main/java/org/elasticsearch/index/query/IntervalBuilder.java

@@ -225,6 +225,8 @@ protected List<IntervalsSource> analyzeGraph(TokenStream source) throws IOExcept
         @Override
         public IntervalIterator intervals(String field, LeafReaderContext ctx) {
             return new IntervalIterator() {
+                boolean exhausted = false;
+
                 @Override
                 public int start() {
                     return NO_MORE_INTERVALS;
@@ -252,16 +254,18 @@ public float matchCost() {
 
                 @Override
                 public int docID() {
-                    return NO_MORE_DOCS;
+                    return exhausted ? NO_MORE_DOCS : -1;
                 }
 
                 @Override
                 public int nextDoc() {
+                    exhausted = true;
                     return NO_MORE_DOCS;
                 }
 
                 @Override
                 public int advance(int target) {
+                    exhausted = true;
                     return NO_MORE_DOCS;
                 }