OAK-10617: oak-search-elastic fix deadlock with includePathRestrictions=false and multiple filtered results

oak-doc/src/site/markdown/query/elastic.md

@@ -33,9 +33,8 @@ however there are differences:
 * Indexes are NOT automatically built when needed: 
   They can be built by setting the `reindex` property to `true` or by using the `oak-run` tool.
   We recommend to build them using the `oak-run` tool.
-* `evaluatePathRestrictions` is only checked at query time (to keep the compatibility with Lucene). The parent paths are
-  always indexed. Changing this flag won't require a reindex then. It's strongly suggested to enable it. This control
-  might be removed in the future.
+* `evaluatePathRestrictions` cannot be disabled. The parent paths are always indexed. Queries with path restrictions are 
+  evaluated at index level when possible, otherwise they are evaluated at repository level.
 * `codec` is ignored.
 * `compatVersion` is ignored.
 * `useIfExists` is ignored.

oak-search-elastic/pom.xml

@@ -101,6 +101,11 @@
       <artifactId>org.apache.felix.scr.annotations</artifactId>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>org.osgi</groupId>
+      <artifactId>org.osgi.annotation.versioning</artifactId>
+      <scope>provided</scope>
+    </dependency>
     <dependency>
       <groupId>org.osgi</groupId>
       <artifactId>org.osgi.service.component.annotations</artifactId>

oak-search-elastic/src/main/java/org/apache/jackrabbit/oak/plugins/index/elastic/ElasticIndexDefinition.java

@@ -59,6 +59,9 @@ public class ElasticIndexDefinition extends IndexDefinition {
     public static final String QUERY_FETCH_SIZES = "queryFetchSizes";
     public static final Long[] QUERY_FETCH_SIZES_DEFAULT = new Long[]{10L, 100L, 1000L};
 
+    public static final String QUERY_TIMEOUT_MS = "queryTimeoutMs";
+    public static final long QUERY_TIMEOUT_MS_DEFAULT = 60000;
+
     public static final String TRACK_TOTAL_HITS = "trackTotalHits";
     public static final Integer TRACK_TOTAL_HITS_DEFAULT = 10000;
 
@@ -138,6 +141,7 @@ public class ElasticIndexDefinition extends IndexDefinition {
     public final int numberOfShards;
     public final int numberOfReplicas;
     public final int[] queryFetchSizes;
+    public final long queryTimeoutMs;
     public final Integer trackTotalHits;
     public final String dynamicMapping;
     public final boolean failOnError;
@@ -162,6 +166,7 @@ public ElasticIndexDefinition(NodeState root, NodeState defn, String indexPath,
         this.similarityTagsBoost = getOptionalValue(defn, SIMILARITY_TAGS_BOOST, SIMILARITY_TAGS_BOOST_DEFAULT);
         this.queryFetchSizes = Arrays.stream(getOptionalValues(defn, QUERY_FETCH_SIZES, Type.LONGS, Long.class, QUERY_FETCH_SIZES_DEFAULT))
                 .mapToInt(Long::intValue).toArray();
+        this.queryTimeoutMs = getOptionalValue(defn, QUERY_TIMEOUT_MS, QUERY_TIMEOUT_MS_DEFAULT);
         this.trackTotalHits = getOptionalValue(defn, TRACK_TOTAL_HITS, TRACK_TOTAL_HITS_DEFAULT);
         this.dynamicMapping = getOptionalValue(defn, DYNAMIC_MAPPING, DYNAMIC_MAPPING_DEFAULT);
         this.failOnError = getOptionalValue(defn, FAIL_ON_ERROR,

oak-search-elastic/src/main/java/org/apache/jackrabbit/oak/plugins/index/elastic/query/ElasticRequestHandler.java

@@ -596,49 +596,47 @@ private List<Query> nonFullTextConstraints(IndexPlan plan, PlanResult planResult
             nodeTypeConstraints.ifPresent(queries::add);
         }
 
-        if (elasticIndexDefinition.evaluatePathRestrictions()) {
-            String path = FulltextIndex.getPathRestriction(plan);
-            switch (filter.getPathRestriction()) {
-                case ALL_CHILDREN:
-                    if (!"/".equals(path)) {
-                        queries.add(newAncestorQuery(path));
+        String path = FulltextIndex.getPathRestriction(plan);
+        switch (filter.getPathRestriction()) {
+            case ALL_CHILDREN:
+                if (!"/".equals(path)) {
+                    queries.add(newAncestorQuery(path));
+                }
+                break;
+            case DIRECT_CHILDREN:
+                queries.add(Query.of(q -> q.bool(b -> b.must(newAncestorQuery(path)).must(newDepthQuery(path, planResult)))));
+                break;
+            case EXACT:
+                // For transformed paths, we can only add path restriction if absolute path to property can be deduced
+                if (planResult.isPathTransformed()) {
+                    String parentPathSegment = planResult.getParentPathSegment();
+                    if (!any.test(PathUtils.elements(parentPathSegment), "*")) {
+                        queries.add(newPathQuery(path + parentPathSegment));
                     }
-                    break;
-                case DIRECT_CHILDREN:
-                    queries.add(Query.of(q -> q.bool(b -> b.must(newAncestorQuery(path)).must(newDepthQuery(path, planResult)))));
-                    break;
-                case EXACT:
+                } else {
+                    queries.add(newPathQuery(path));
+                }
+                break;
+            case PARENT:
+                if (PathUtils.denotesRoot(path)) {
+                    // there's no parent of the root node
+                    // we add a path that can not possibly occur because there
+                    // is no way to say "match no documents" in Lucene
+                    queries.add(newPathQuery("///"));
+                } else {
                     // For transformed paths, we can only add path restriction if absolute path to property can be deduced
                     if (planResult.isPathTransformed()) {
                         String parentPathSegment = planResult.getParentPathSegment();
                         if (!any.test(PathUtils.elements(parentPathSegment), "*")) {
-                            queries.add(newPathQuery(path + parentPathSegment));
+                            queries.add(newPathQuery(PathUtils.getParentPath(path) + parentPathSegment));
                         }
                     } else {
-                        queries.add(newPathQuery(path));
+                        queries.add(newPathQuery(PathUtils.getParentPath(path)));
                     }
-                    break;
-                case PARENT:
-                    if (PathUtils.denotesRoot(path)) {
-                        // there's no parent of the root node
-                        // we add a path that can not possibly occur because there
-                        // is no way to say "match no documents" in Lucene
-                        queries.add(newPathQuery("///"));
-                    } else {
-                        // For transformed paths, we can only add path restriction if absolute path to property can be deduced
-                        if (planResult.isPathTransformed()) {
-                            String parentPathSegment = planResult.getParentPathSegment();
-                            if (!any.test(PathUtils.elements(parentPathSegment), "*")) {
-                                queries.add(newPathQuery(PathUtils.getParentPath(path) + parentPathSegment));
-                            }
-                        } else {
-                            queries.add(newPathQuery(PathUtils.getParentPath(path)));
-                        }
-                    }
-                    break;
-                case NO_RESTRICTION:
-                    break;
-            }
+                }
+                break;
+            case NO_RESTRICTION:
+                break;
         }
 
         for (Filter.PropertyRestriction pr : filter.getPropertyRestrictions()) {

oak-search-elastic/src/main/java/org/apache/jackrabbit/oak/plugins/index/elastic/query/async/ElasticResponseListener.java

@@ -20,17 +20,18 @@
 import co.elastic.clients.elasticsearch.core.search.Hit;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import org.apache.jackrabbit.oak.plugins.index.search.FieldNames;
+import org.osgi.annotation.versioning.ProviderType;
 
-import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
 
 /**
  * Generic listener of Elastic response
  */
+@ProviderType
 public interface ElasticResponseListener {
 
-    Set<String> DEFAULT_SOURCE_FIELDS = Collections.singleton(FieldNames.PATH);
+    Set<String> DEFAULT_SOURCE_FIELDS = Set.of(FieldNames.PATH);
 
     /**
      * Returns the source fields this listener is interested on
@@ -68,8 +69,9 @@ default void startData(long totalHits) { /*empty*/ }
         /**
          * This method is called for each {@link Hit} retrieved
          * @param searchHit a search result
+         * @return true if the search hit was successfully processed, false otherwise
          */
-        void on(Hit<ObjectNode> searchHit);
+        boolean on(Hit<ObjectNode> searchHit);
     }
 
     /**

oak-search-elastic/src/main/java/org/apache/jackrabbit/oak/plugins/index/elastic/query/async/ElasticResultRowAsyncIterator.java

@@ -41,13 +41,15 @@
 import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
+import java.util.BitSet;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
@@ -69,7 +71,7 @@ public class ElasticResultRowAsyncIterator implements ElasticQueryIterator, Elas
     private static final FulltextResultRow POISON_PILL =
             new FulltextResultRow("___OAK_POISON_PILL___", 0d, Collections.emptyMap(), null, null);
 
-    private final BlockingQueue<FulltextResultRow> queue = new LinkedBlockingQueue<>();
+    private final BlockingQueue<FulltextResultRow> queue;
 
     private final ElasticIndexNode indexNode;
     private final IndexPlan indexPlan;
@@ -96,6 +98,9 @@ public ElasticResultRowAsyncIterator(@NotNull ElasticIndexNode indexNode,
         this.rowInclusionPredicate = rowInclusionPredicate;
         this.metricHandler = metricHandler;
         this.elasticFacetProvider = elasticRequestHandler.getAsyncFacetProvider(indexNode.getConnection(), elasticResponseHandler);
+        // set the queue size to the limit of the query. This is to avoid to load too many results in memory in case the
+        // consumer is slow to process them
+        this.queue = new LinkedBlockingQueue<>((int) indexPlan.getFilter().getQueryLimits().getLimitReads());
         this.elasticQueryScanner = initScanner();
     }
 
@@ -108,7 +113,7 @@ public boolean hasNext() {
                 elasticQueryScanner.scan();
             }
             try {
-                nextRow = queue.take();
+                nextRow = queue.poll(indexNode.getDefinition().queryTimeoutMs, TimeUnit.MILLISECONDS);
             } catch (InterruptedException e) {
                 Thread.currentThread().interrupt();  // restore interrupt status
                 throw new IllegalStateException("Error reading next result from Elastic", e);
@@ -144,12 +149,12 @@ public FulltextResultRow next() {
     }
 
     @Override
-    public void on(Hit<ObjectNode> searchHit) {
+    public boolean on(Hit<ObjectNode> searchHit) {
         final String path = elasticResponseHandler.getPath(searchHit);
         if (path != null) {
             if (rowInclusionPredicate != null && !rowInclusionPredicate.test(path)) {
                 LOG.trace("Path {} not included because of hierarchy inclusion rules", path);
-                return;
+                return false;
             }
             LOG.trace("Path {} satisfies hierarchy inclusion rules", path);
             try {
@@ -159,7 +164,9 @@ public void on(Hit<ObjectNode> searchHit) {
                 Thread.currentThread().interrupt();  // restore interrupt status
                 throw new IllegalStateException("Error producing results into the iterator queue", e);
             }
+            return true;
         }
+        return false;
     }
 
     @Override
@@ -333,16 +340,25 @@ public void onSuccess(SearchResponse<ObjectNode> searchResponse) {
                 }
 
                 LOG.trace("Emitting {} search hits, for a total of {} scanned results", searchHits.size(), scannedRows);
+
+                BitSet listenersWithHits = new BitSet(searchHitListeners.size());
+
                 for (Hit<ObjectNode> hit : searchHits) {
-                    for (SearchHitListener l : searchHitListeners) {
-                        l.on(hit);
+                    for (int index = 0; index < searchHitListeners.size(); index++) {
+                        SearchHitListener l = searchHitListeners.get(index);
+                        if (l.on(hit)) {
+                            listenersWithHits.set(index);
+                        }
                     }
                 }
+                // if any listener has not processed any hit, it means we need to load more data since there could be
+                // listeners waiting for some results before triggering a new scan
+                boolean areAllListenersProcessed = listenersWithHits.cardinality() == searchHitListeners.size();
 
                 if (!anyDataLeft.get()) {
                     LOG.trace("No data left: closing scanner, notifying listeners");
                     close();
-                } else if (fullScan) {
+                } else if (fullScan || !areAllListenersProcessed) {
                     scan();
                 }
             } else {

oak-search-elastic/src/main/java/org/apache/jackrabbit/oak/plugins/index/elastic/query/async/facets/ElasticSecureFacetAsyncProvider.java

@@ -71,7 +71,7 @@ public boolean isFullScan() {
     }
 
     @Override
-    public void on(Hit<ObjectNode> searchHit) {
+    public boolean on(Hit<ObjectNode> searchHit) {
         final String path = elasticResponseHandler.getPath(searchHit);
         if (path != null && isAccessible.test(path)) {
             for (String field: facetFields) {
@@ -90,6 +90,7 @@ public void on(Hit<ObjectNode> searchHit) {
                 }
             }
         }
+        return true;
     }
 
     @Override

oak-search-elastic/src/test/java/org/apache/jackrabbit/oak/plugins/index/elastic/ElasticIndexDescendantSpellcheckCommonTest.java

@@ -20,6 +20,8 @@
 import org.apache.jackrabbit.oak.jcr.Jcr;
 import org.apache.jackrabbit.oak.plugins.index.IndexDescendantSpellcheckCommonTest;
 import org.junit.ClassRule;
+import org.junit.Ignore;
+import org.junit.Test;
 
 import javax.jcr.Repository;
 
@@ -38,4 +40,10 @@ protected Repository createJcrRepository() {
         return jcr.createRepository();
     }
 
+    @Override
+    @Test
+    @Ignore("OAK-10617: path restrictions are always applied. This test is not applicable for Elastic")
+    public void descendantSuggestionRequirePathRestrictionIndex() throws Exception {
+        super.descendantSuggestionRequirePathRestrictionIndex();
+    }
 }