Hi Pieter,
can you create a Jira ticket for this issue? I think it's a general problem
related to mutating steps and a strategy that inserts BarrierSteps in front
of mutating steps should solve this and a few other issues.
Cheers,
Daniel
On Thu, Nov 30, 2017 at 8:28 AM, pieter gmail <pieter.mar...@gmail.com>
wrote:
> Hi,
>
> Any ideas about this one?
>
> Thanks
> Pieter
>
>
> On 22/11/2017 19:49, pieter gmail wrote:
>
>> Hi,
>>
>> Whilst optimizing the DropStep in Sqlg I came across RepeatStep plus
>> DropStep in a traversal going into a infinite loop.
>>
>> To test Sqlg I tested on TinkerPop's ComplexTest.playlistPath() changing
>> the gremlin to have a drop()
>>
>> @Test
>> public void testDropPlaylist() {
>> final TinkerGraph g = TinkerGraph.open();
>> Io.Builder<GraphSONIo> builder = GraphSONIo.build(GraphSONVersi
>> on.V3_0);
>> final GraphReader reader = g.io(builder).reader().create();
>> try (final InputStream stream = AbstractGremlinTest.class.getR
>> esourceAsStream("/grateful-dead-v3d0.json")) {
>> reader.readGraph(stream, g);
>> } catch (IOException e) {
>> Assert.fail(e.getMessage());
>> }
>> Traversal<Vertex, Vertex> playListTraversal = getPlaylistPaths(g);
>> System.out.println(playListTraversal.toString());
>> List<Vertex> vertices = playListTraversal.toList();
>> Assert.assertEquals(100, vertices.size());
>> System.out.println("counted");
>> Traversal<Vertex, Vertex> dropTraversal =
>> getPlaylistPaths(g).drop().drop().iterate();
>> System.out.println("done");
>> }
>>
>> public GraphTraversal<Vertex, Vertex> getPlaylistPaths(Graph graph) {
>> return graph.traversal().V().has("name",
>> "Bob_Dylan").in("sungBy").as("a").
>> repeat(__.out().order().by(Order.shuffle).simplePath().from("a")).
>> until(__.out("writtenBy").has("name",
>> "Johnny_Cash")).limit(1).as("b").
>> repeat(__.out().order().by(Order.shuffle).as("c").simplePath().from("b").to("c")).
>>
>> until(__.out("sungBy").has("name",
>> "Grateful_Dead")).limit(100);
>> }
>>
>> The second dropTraversal goes into an infinite loop.
>>
>> A simpler scenario illustrating the infinite loop,
>>
>> @Test
>> public void testRepeatDrop() {
>> final TinkerGraph g = TinkerGraph.open();
>> Vertex a1 = g.addVertex(T.label, "A");
>> Vertex b1 = g.addVertex(T.label, "B");
>> Vertex c1 = g.addVertex(T.label, "C");
>> a1.addEdge("ab", b1);
>> b1.addEdge("ba", a1);
>> b1.addEdge("bc", c1);
>>
>> Vertex a2 = g.addVertex(T.label, "A");
>> Vertex b2 = g.addVertex(T.label, "B");
>> Vertex c2 = g.addVertex(T.label, "C");
>> a2.addEdge("ab", b2);
>> b2.addEdge("ba", a2);
>> b2.addEdge("bc", c2);
>>
>> a1.addEdge("ac", c1);
>> a1.addEdge("ac", c2);
>>
>> List<Vertex> vertices = g.traversal().withoutStrategie
>> s(LazyBarrierStrategy.class)
>> .V().hasLabel("A")
>> .repeat(__.out("ab", "ba"))
>> .until(__.out("bc"))
>> .out("bc")
>> .in("ac")
>> .out("ac")
>> .toList();
>> Assert.assertEquals(4, vertices.size());
>> g.traversal().withoutStrategies(LazyBarrierStrategy.class)
>> .V().hasLabel("A")
>> .repeat(__.out("ab", "ba"))
>> .until(__.out("bc"))
>> .out("bc")
>> .in("ac")
>> .out("ac")
>> .drop()
>> .iterate();
>> System.out.println("asdasdasd");
>> }
>>
>> Adding a BarrierStep before drop() resolves the issue but probably this
>> should happen automatically in a strategy?
>> Afraid I can not quite tell what the scenarios are that would cause this
>> issue so not sure if a BarrierStep should always be added or only sometimes.
>>
>> Cheers
>> Pieter
>>
>>
>>
>
