Gh-3334: Fix Gremlin Reusing Accumulo Iterators

library/tinkerpop/src/main/java/uk/gov/gchq/gaffer/tinkerpop/GafferPopGraph.java

@@ -412,7 +412,6 @@ public void addEdge(final GafferPopEdge edge) {
     public Iterator<Vertex> vertices(final Object... vertexIds) {
         final boolean getAll = null == vertexIds || 0 == vertexIds.length;
         final OperationChain<Iterable<? extends Element>> getOperation;
-        final Iterable<Vertex> orphanVertices;
 
         LOGGER.debug(GET_DEBUG_MSG, variables.getElementsLimit());
         if (getAll) {
@@ -430,29 +429,28 @@ public Iterator<Vertex> vertices(final Object... vertexIds) {
                 .then(new Limit<Element>(variables.getElementsLimit(), true))
                 .build();
         }
-        // Run requested chain on the graph
-        final Iterable<? extends Element> result = execute(getOperation);
+        // Run requested chain on the graph and buffer result to set to avoid reusing iterator
+        final Set<Element> result = new HashSet<>(IterableUtils.toList(execute(getOperation)));
 
         // Translate results to Gafferpop elements
         final GafferPopElementGenerator generator = new GafferPopElementGenerator(this);
-        final Iterable<Vertex> translatedResults = () -> StreamSupport.stream(result.spliterator(), false)
+        final Set<Vertex> translatedResults = StreamSupport.stream(result.spliterator(), false)
                 .map(generator::_apply)
                 .filter(Vertex.class::isInstance)
                 .map(e -> (Vertex) e)
                 .limit(variables.getElementsLimit())
-                .iterator();
+                .collect(Collectors.toSet());
 
-        if (IterableUtils.size(translatedResults) >= variables.getElementsLimit()) {
+        if (translatedResults.size() >= variables.getElementsLimit()) {
             LOGGER.warn(
                 "Result size is greater than or equal to configured limit ({}). Results may have been truncated",
                 variables.getElementsLimit());
         }
 
         // Check for seeds that are not entities but are vertices on an edge (orphan vertices)
-        orphanVertices = GafferVertexUtils.getOrphanVertices(result, this, vertexIds);
-        Iterable<Vertex> chainedIterable = IterableUtils.chainedIterable(translatedResults, orphanVertices);
+        translatedResults.addAll(GafferVertexUtils.getOrphanVertices(result, this, vertexIds));
 
-        return chainedIterable.iterator();
+        return translatedResults.iterator();
     }
 
     /**
@@ -597,19 +595,19 @@ public Iterator<Edge> edges(final Object... elementIds) {
                 .build();
         }
 
-        // Run requested chain on the graph
-        final Iterable<? extends Element> result = execute(getOperation);
+        // Run requested chain on the graph and buffer to set to avoid reusing iterator
+        final Set<Element> result = new HashSet<>(IterableUtils.toList(execute(getOperation)));
 
         // Translate results to Gafferpop elements
         final GafferPopElementGenerator generator = new GafferPopElementGenerator(this);
-        final Iterable<Edge> translatedResults = () -> StreamSupport.stream(result.spliterator(), false)
+        final Set<Edge> translatedResults = StreamSupport.stream(result.spliterator(), false)
                 .map(generator::_apply)
                 .filter(Edge.class::isInstance)
                 .map(e -> (Edge) e)
                 .limit(variables.getElementsLimit())
-                .iterator();
+                .collect(Collectors.toSet());
 
-        if (IterableUtils.size(translatedResults) >= variables.getElementsLimit()) {
+        if (translatedResults.size() >= variables.getElementsLimit()) {
             LOGGER.warn(
                 "Result size is greater than or equal to configured limit ({}). Results may have been truncated",
                 variables.getElementsLimit());
@@ -811,20 +809,19 @@ private Iterator<GafferPopVertex> verticesWithSeedsAndView(final List<ElementSee
             }
         }
 
-        // Run operation on graph
-        final Iterable<? extends Element> result = execute(getOperation);
+        // Run operation on graph buffer to set to avoid reusing iterator
+        final Set<Element> result = new HashSet<>(IterableUtils.toList(execute(getOperation)));
 
         // Translate results to Gafferpop elements
         final GafferPopElementGenerator generator = new GafferPopElementGenerator(this);
-        final Iterable<GafferPopVertex> translatedResults = () -> StreamSupport.stream(result.spliterator(), false)
+        final Set<GafferPopVertex> translatedResults = StreamSupport.stream(result.spliterator(), false)
                 .map(generator::_apply)
                 .filter(GafferPopVertex.class::isInstance)
                 .map(e -> (GafferPopVertex) e)
                 .limit(variables.getElementsLimit())
-                .iterator();
+                .collect(Collectors.toSet());
 
         return translatedResults.iterator();
-
     }
 
     private Iterator<Vertex> adjVerticesWithSeedsAndView(final List<ElementSeed> seeds, final Direction direction, final View view) {
@@ -840,30 +837,29 @@ private Iterator<Vertex> adjVerticesWithSeedsAndView(final List<ElementSeed> see
                     .build())
                 .build());
 
-        List<EntityId> seedList = StreamSupport.stream(getAdjEntitySeeds.spliterator(), false).collect(Collectors.toList());
+        List<? extends EntityId> seedList = IterableUtils.toList(getAdjEntitySeeds);
 
         // GetAdjacentIds provides list of entity seeds so run a GetElements to get the actual Entities
-        final Iterable<? extends Element> result = execute(new OperationChain.Builder()
-                .first(new GetElements.Builder()
-                    .input(seedList)
-                    .build())
-                .build());
+        final Set<Element> result = new HashSet<>(IterableUtils.toList(
+            execute(new OperationChain.Builder()
+                    .first(new GetElements.Builder()
+                        .input(seedList)
+                        .build())
+                    .build())));
 
         // Translate results to Gafferpop elements
         final GafferPopElementGenerator generator = new GafferPopElementGenerator(this);
-        final Iterable<Vertex> translatedResults = () -> StreamSupport.stream(result.spliterator(), false)
+        final Set<Vertex> translatedResults = StreamSupport.stream(result.spliterator(), false)
                 .map(generator::_apply)
                 .filter(Vertex.class::isInstance)
                 .map(e -> (Vertex) e)
-                .iterator();
+                .collect(Collectors.toSet());
 
         // Check for seeds that are not entities but are vertices on an edge (orphan vertices)
-        Iterable<Vertex> chainedIterable = translatedResults;
         for (final EntityId seed : seedList) {
-            Iterable<Vertex> orphanVertices = GafferVertexUtils.getOrphanVertices(result, this, seed.getVertex());
-            chainedIterable = IterableUtils.chainedIterable(chainedIterable, orphanVertices);
+            translatedResults.addAll(GafferVertexUtils.getOrphanVertices(result, this, seed.getVertex()));
         }
-        return chainedIterable.iterator();
+        return translatedResults.iterator();
     }
 
     private Iterator<Edge> edgesWithSeedsAndView(final List<ElementSeed> seeds, final Direction direction, final View view) {
@@ -900,16 +896,16 @@ private Iterator<Edge> edgesWithSeedsAndView(final List<ElementSeed> seeds, fina
         }
 
         // Run requested chain on the graph
-        final Iterable<? extends Element> result = execute(getOperation);
+        final Set<Element> result = new HashSet<>(IterableUtils.toList(execute(getOperation)));
 
         // Translate results to Gafferpop elements
         final GafferPopElementGenerator generator = new GafferPopElementGenerator(this, true);
-        final Iterable<Edge> translatedResults = () -> StreamSupport.stream(result.spliterator(), false)
+        final Set<Edge> translatedResults = StreamSupport.stream(result.spliterator(), false)
                 .map(generator::_apply)
                 .filter(Edge.class::isInstance)
                 .map(e -> (Edge) e)
                 .limit(variables.getElementsLimit())
-                .iterator();
+                .collect(Collectors.toSet());
 
         return translatedResults.iterator();
     }

library/tinkerpop/src/main/java/uk/gov/gchq/gaffer/tinkerpop/process/traversal/step/GafferPopGraphStep.java

@@ -69,7 +69,8 @@ public class GafferPopGraphStep<S, E extends Element> extends GraphStep<S, E> im
     public GafferPopGraphStep(final GraphStep<S, E> originalGraphStep) {
         super(originalGraphStep.getTraversal(), originalGraphStep.getReturnClass(), originalGraphStep.isStartStep(), originalGraphStep.getIds());
         LOGGER.debug("Running custom GraphStep on GafferPopGraph");
-        originalGraphStep.getLabels().forEach(this::addLabel);
+        this.labels = originalGraphStep.getLabels();
+        this.parameters = originalGraphStep.getParameters();
 
         // Save reference to the graph
         GafferPopGraph graph = (GafferPopGraph) originalGraphStep.getTraversal().getGraph().get();

library/tinkerpop/src/main/java/uk/gov/gchq/gaffer/tinkerpop/process/traversal/step/GafferPopHasStep.java

@@ -37,7 +37,7 @@ public class GafferPopHasStep<S extends Element> extends HasStep<S> {
     public GafferPopHasStep(final HasStep<S> originalHasStep) {
         super(originalHasStep.getTraversal());
         LOGGER.debug("Running custom HasStep on GafferPopGraph");
-
+        this.labels = originalHasStep.getLabels();
         originalHasStep.getHasContainers().forEach(this::addHasContainer);
     }
 

library/tinkerpop/src/main/java/uk/gov/gchq/gaffer/tinkerpop/process/traversal/step/GafferPopVertexStep.java

@@ -62,7 +62,7 @@
  * (GafferPop) g.V().out() = [v2, v3, v4, v5]
  * </pre>
  */
-public class GafferPopVertexStep<E extends Element> extends FlatMapStep<Iterable<Vertex>, E>
+public class GafferPopVertexStep<E extends Element> extends FlatMapStep<List<Vertex>, E>
         implements AutoCloseable, Configuring {
     private static final Logger LOGGER = LoggerFactory.getLogger(GafferPopVertexStep.class);
 
@@ -77,6 +77,7 @@ public GafferPopVertexStep(final VertexStep<E> originalVertexStep) {
         this.edgeLabels = originalVertexStep.getEdgeLabels();
         this.returnClass = originalVertexStep.getReturnClass();
         this.traversal = originalVertexStep.getTraversal();
+        this.labels = originalVertexStep.getLabels();
     }
 
     @Override
@@ -90,7 +91,7 @@ public void configure(final Object... keyValues) {
     }
 
     @Override
-    protected Iterator<E> flatMap(final Traverser.Admin<Iterable<Vertex>> traverser) {
+    protected Iterator<E> flatMap(final Traverser.Admin<List<Vertex>> traverser) {
         return Vertex.class.isAssignableFrom(returnClass) ?
             (Iterator<E>) this.vertices(traverser.get()) :
             (Iterator<E>) this.edges(traverser.get());

library/tinkerpop/src/main/java/uk/gov/gchq/gaffer/tinkerpop/process/traversal/strategy/optimisation/GafferPopVertexStepStrategy.java

@@ -18,6 +18,7 @@
 
 import org.apache.tinkerpop.gremlin.process.traversal.Traversal.Admin;
 import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy;
+import org.apache.tinkerpop.gremlin.process.traversal.step.map.FoldStep;
 import org.apache.tinkerpop.gremlin.process.traversal.step.map.VertexStep;
 import org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy;
 import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper;
@@ -27,7 +28,8 @@
 import org.slf4j.LoggerFactory;
 
 import uk.gov.gchq.gaffer.tinkerpop.process.traversal.step.GafferPopVertexStep;
-import uk.gov.gchq.gaffer.tinkerpop.process.traversal.step.LazyFoldStep;
+
+import java.util.List;
 
 /**
  * Optimisation strategy to reduce the number of Gaffer operations performed.
@@ -49,14 +51,13 @@ public void apply(final Admin<?, ?> traversal) {
             LOGGER.debug("Inserting FoldStep and replacing VertexStep");
 
             // Replace vertex step
-            final GafferPopVertexStep<? extends Element> listVertexStep = new GafferPopVertexStep<>(
-                    originalVertexStep);
+            final GafferPopVertexStep<? extends Element> listVertexStep = new GafferPopVertexStep<>(originalVertexStep);
             TraversalHelper.replaceStep(originalVertexStep, listVertexStep, traversal);
 
             // Add in a fold step before the new VertexStep so that the input is the list of
             // all vertices
-            LazyFoldStep<Vertex> lazyFoldStep = new LazyFoldStep<>(originalVertexStep.getTraversal());
-            TraversalHelper.insertBeforeStep(lazyFoldStep, listVertexStep, traversal);
+            FoldStep<Vertex, List<Vertex>> foldStep = new FoldStep<>(originalVertexStep.getTraversal());
+            TraversalHelper.insertBeforeStep(foldStep, listVertexStep, traversal);
         });
     }
 

library/tinkerpop/src/main/java/uk/gov/gchq/gaffer/tinkerpop/process/traversal/util/GafferVertexUtils.java

@@ -27,8 +27,8 @@
 import uk.gov.gchq.gaffer.tinkerpop.GafferPopGraph;
 import uk.gov.gchq.gaffer.tinkerpop.GafferPopVertex;
 
-import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -42,18 +42,19 @@ private GafferVertexUtils() {
     }
 
     /**
-     * Util method to extract vertices that are vertices on an edge but do not have an
+     * Util method to extract vertices that are vertices on an edge but do not have
+     * an
      * associated {@link Vertex} or {@link Entity} the current graph.
      * These vertices exist only on an edge.
      *
      *
-     * @param result The results from a Gaffer query
-     * @param graph The GafferPop graph being queried
+     * @param result    The results from a Gaffer query
+     * @param graph     The GafferPop graph being queried
      * @param vertexIds The vertexIds that have been used as seeds in the query
-     * @return Iterable of 'orphan' {@link Vertex}'s
+     * @return {@link Collection} of 'orphan' {@link Vertex}'s
      */
 
-    public static Iterable<Vertex> getOrphanVertices(final Iterable<? extends Element> result, final GafferPopGraph graph, final Object... vertexIds) {
+    public static Collection<Vertex> getOrphanVertices(final Iterable<? extends Element> result, final GafferPopGraph graph, final Object... vertexIds) {
         // Check for any vertex ID seeds that are not returned as Entities
         List<Object> orphanVertexIds = Arrays.stream(vertexIds)
             .filter(id -> StreamSupport.stream(result.spliterator(), false)
@@ -73,21 +74,23 @@ public static Iterable<Vertex> getOrphanVertices(final Iterable<? extends Elemen
      * @param result The results of a Gaffer query
      * @param graph The GafferPop graph being queried
      * @param orphanVertexIds Any seeds that were not found to have an entity
-     * @return Iterable of 'orphan' {@link Vertex}'s
+     * @return {@link Collection} of 'orphan' {@link Vertex}'s
      */
-    private static Iterable<Vertex> extractOrphanVerticesFromEdges(final Iterable<? extends Element> result, final GafferPopGraph graph, final List<Object> orphanVertexIds) {
-        List<Vertex> orphanVertices = new ArrayList<>();
-        StreamSupport.stream(result.spliterator(), false)
-            .filter(Edge.class::isInstance)
-            .map(e -> (Edge) e)
-            .forEach(e -> {
-                if (orphanVertexIds.contains(e.getSource()) || orphanVertexIds.equals(e.getSource())) {
-                    orphanVertices.add(new GafferPopVertex(GafferPopGraph.ID_LABEL, GafferCustomTypeFactory.parseForGraphSONv3(e.getSource()), graph));
-                }
-                if (orphanVertexIds.contains(e.getDestination()) || orphanVertexIds.equals(e.getDestination())) {
-                    orphanVertices.add(new GafferPopVertex(GafferPopGraph.ID_LABEL, GafferCustomTypeFactory.parseForGraphSONv3(e.getDestination()), graph));
-                }
-            });
-        return orphanVertices;
+    private static Collection<Vertex> extractOrphanVerticesFromEdges(final Iterable<? extends Element> result, final GafferPopGraph graph, final List<Object> orphanVertexIds) {
+    return StreamSupport.stream(result.spliterator(), false)
+        .filter(Edge.class::isInstance)
+        .map(e -> (Edge) e)
+        .map(e -> {
+            if (orphanVertexIds.contains(e.getSource()) || orphanVertexIds.equals(e.getSource())) {
+                return new GafferPopVertex(GafferPopGraph.ID_LABEL, GafferCustomTypeFactory.parseForGraphSONv3(e.getSource()), graph);
+            }
+            if (orphanVertexIds.contains(e.getDestination()) || orphanVertexIds.equals(e.getDestination())) {
+                return new GafferPopVertex(GafferPopGraph.ID_LABEL, GafferCustomTypeFactory.parseForGraphSONv3(e.getDestination()), graph);
+            }
+            return e;
+        })
+        .filter(Vertex.class::isInstance)
+        .map(v -> (Vertex) v)
+        .collect(Collectors.toSet());
     }
 }

library/tinkerpop/src/test/java/uk/gov/gchq/gaffer/tinkerpop/GafferPopGraphTest.java

@@ -507,7 +507,7 @@ void shouldGetAllEdges() {
         final Iterator<Edge> edges = graph.edges();
 
         // Then
-        assertThat(edges).toIterable().containsExactly(createdEdge, knowsEdge);
+        assertThat(edges).toIterable().containsExactlyInAnyOrder(createdEdge, knowsEdge);
     }
 
     @Test

library/tinkerpop/src/test/java/uk/gov/gchq/gaffer/tinkerpop/process/traversal/strategy/GafferPopGraphStepStrategyCypherIT.java

@@ -45,7 +45,7 @@ class GafferPopGraphStepStrategyCypherIT {
 
     @BeforeAll
     public static void beforeAll() {
-        GafferPopGraph gafferPopGraph = GafferPopModernTestUtils.createModernGraph(GafferPopGraphStepStrategyCypherIT.class, StoreType.MAP);
+        GafferPopGraph gafferPopGraph = GafferPopModernTestUtils.createModernGraph(GafferPopGraphStepStrategyCypherIT.class, StoreType.ACCUMULO);
         g = gafferPopGraph.traversal();
     }