[jira] [Commented] (TINKERPOP-1519) TinkerGraphComputer doesn't handle multiple MessageScopes in single iteration

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TINKERPOP-1519?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16053760#comment-16053760 ] 

ASF GitHub Bot commented on TINKERPOP-1519:
-------------------------------------------

GitHub user sheldonkhall opened a pull request:

    https://github.com/apache/tinkerpop/pull/632

    TINKERPOP-1519: tinker graph computer does not handle multiple scopes

    https://issues.apache.org/jira/browse/TINKERPOP-1519
    
    This change modifies the tinker graph computer so that each message sent in a vertex program remembers its scope. Previously when the receiveMessages method on TinkerMessenger was called it would loop through ALL message scopes and then ALL messages, which is incorrect. Now the method loops over each scope, and then each message within that scope.
    
    I have added the regression test suggested in the JIRA ticket and run mvn clean install locally to confirm everything passes OK.
    
    I had a quick look at the latest master, and this bugfix may need to be merged there too.


You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/sheldonkhall/tinkerpop tp31

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/tinkerpop/pull/632.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #632
    
----
commit 28c514da9065683ed90ea6aabc66ffdcbab99c11
Author: Sheldon <sh...@mindmaps.io>
Date:   2017-06-15T17:00:32Z

    bugfix

commit 99679a037db3e86112471a40cd454114231852b6
Author: Sheldon <sh...@mindmaps.io>
Date:   2017-06-19T09:35:16Z

    add the regression test

----


> TinkerGraphComputer doesn't handle multiple MessageScopes in single iteration
> -----------------------------------------------------------------------------
>
>                 Key: TINKERPOP-1519
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1519
>             Project: TinkerPop
>          Issue Type: Bug
>          Components: tinkergraph
>    Affects Versions: 3.1.1-incubating
>         Environment: Mac OSX
>            Reporter: Felix Chapman
>            Priority: Minor
>
> When executing a VertexProgram that sends messages on multiple MessageScopes in a single iteration, then the messages behave as if they were sent on all scopes within that iteration.
> e.g. if you send message {{A}} on {{out}} edges, and message {{B}} on {{in}} edges, then {{A}} and {{B}} will instead be sent over both {{in}} and {{out}} edges.
> The problem can be resolved by using only a single MessageScope per iteration, but this involves increasing the number of iterations.
> An example of this behaviour is below:
> {code:java}
> public class TinkerTest {
>     public static void main(String[] args) throws ExecutionException, InterruptedException {
>         TinkerGraph graph = TinkerGraph.open();
>         Vertex a = graph.addVertex("a");
>         Vertex b = graph.addVertex("b");
>         Vertex c = graph.addVertex("c");
>         a.addEdge("edge", b);
>         b.addEdge("edge", c);
>         // Simple graph:
>         // a -> b -> c
>         // Execute a traversal program that sends an incoming message of "2" and an outgoing message of "1" from "b"
>         // then each vertex sums any received messages
>         ComputerResult result = graph.compute().program(new MyVertexProgram()).submit().get();
>         // We expect the results to be {a=2, b=0, c=1}. Instead it is {a=3, b=0, c=3}
>         System.out.println(result.graph().traversal().V().group().by(Element::label).by("count").next());
>     }
> }
> class MyVertexProgram implements VertexProgram<Long> {
>     private final MessageScope.Local<Long> countMessageScopeIn = MessageScope.Local.of(__::inE);
>     private final MessageScope.Local<Long> countMessageScopeOut = MessageScope.Local.of(__::outE);
>     private static final String MEMORY_KEY = "count";
>     private static final Set<String> COMPUTE_KEYS = Collections.singleton(MEMORY_KEY);
>     @Override
>     public void setup(final Memory memory) {}
>     @Override
>     public GraphComputer.Persist getPreferredPersist() {
>         return GraphComputer.Persist.VERTEX_PROPERTIES;
>     }
>     @Override
>     public Set<String> getElementComputeKeys() {
>         return COMPUTE_KEYS;
>     }
>     @Override
>     public Set<MessageScope> getMessageScopes(final Memory memory) {
>         return Sets.newHashSet(countMessageScopeIn, countMessageScopeOut);
>     }
>     @Override
>     public void execute(Vertex vertex, Messenger<Long> messenger, Memory memory) {
>         switch (memory.getIteration()) {
>             case 0:
>                 if (vertex.label().equals("b")) {
>                     messenger.sendMessage(this.countMessageScopeIn, 2L);
>                     messenger.sendMessage(this.countMessageScopeOut, 1L);
>                 }
>                 break;
>             case 1:
>                 long edgeCount = IteratorUtils.reduce(messenger.receiveMessages(), 0L, (a, b) -> a + b);
>                 vertex.property(MEMORY_KEY, edgeCount);
>                 break;
>         }
>     }
>     @Override
>     public boolean terminate(final Memory memory) {
>         return memory.getIteration() == 1;
>     }
>     @Override
>     public GraphComputer.ResultGraph getPreferredResultGraph() {
>         return GraphComputer.ResultGraph.NEW;
>     }
>     @Override
>     public MyVertexProgram clone() {
>         try {
>             return (MyVertexProgram) super.clone();
>         } catch (final CloneNotSupportedException e) {
>             throw new RuntimeException(e);
>         }
>     }
> }
> {code}



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