[jira] [Commented] (TINKERPOP-1822) Repeat should depth first search

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

    [ https://issues.apache.org/jira/browse/TINKERPOP-1822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16500162#comment-16500162 ] 

ASF GitHub Bot commented on TINKERPOP-1822:
-------------------------------------------

Github user krlohnes commented on a diff in the pull request:

    https://github.com/apache/tinkerpop/pull/838#discussion_r192728027
  
    --- Diff: gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/branch/RepeatStep.java ---
    @@ -273,11 +300,40 @@ public RepeatEndStep(final Traversal.Admin traversal) {
                 super(traversal);
             }
     
    +        final LinkedList<Traverser.Admin<S>> stashedStarts = new LinkedList<>();
    --- End diff --
    
    Sorry for the delay, things have gotten fairly busy for me. I'd given a little bit of thought around this, but not a whole lot. I don't think this needs to be a linked list, it could likely an ArrayList or an ArrayDeque and the entries would take up less memory. ArrayDeque may be preferable for large graphs since it'll resize less frequently than an ArrayList, but it will consume more memory than an ArrayList by default.
    
    However, I think having a `stashedStarts` here is necessary from the view of "one piece of code serving 2 algorithms" If this were to be completely rewritten as DFS (I don't know how to do that at this point, but for the sake of argument), and there was a desire to use the same code to utilize BFS, there'd likely be a need to have stashed starts to achieve BFS. 
    
    That's about as far as I've gotten in thinking about this for now.


> Repeat should depth first search
> --------------------------------
>
>                 Key: TINKERPOP-1822
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1822
>             Project: TinkerPop
>          Issue Type: Improvement
>          Components: process
>    Affects Versions: 3.3.0, 3.2.6
>            Reporter: Robert Dale
>            Priority: Major
>
> Perhaps optionally.
> See also:
> * https://groups.google.com/forum/#!topic/gremlin-users/gLSLxH_K-wE
> * https://github.com/apache/tinkerpop/pull/715



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