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https://issues.apache.org/jira/browse/TINKERPOP-2396?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
redtree updated TINKERPOP-2396:
-------------------------------
Description:
Currently in many TinkerPop steps, TraverserSet is internally created and used.
However GraphDB provider may want to use their own TraverserSet to change the
logic how it populates an inner Map.
Just let me give one example
Say internally we have a different representation of id (which won't be exposed
to client when the result is returned) for each element and want to use it for
hash key.
Because we can't overwrite ElementHelper's behavior so first we tried
overriding Element#hashCode but after that we saw that this test effectively
fails.
[https://github.com/apache/tinkerpop/blob/cff4c161615f2b50bda27b6ba523c7f52b833532/gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/structure/util/detached/DetachedVertexTest.java#L75]
Here v is our own custom vertex instance which uses internal id for hashCode
but DetachedVertex just uses a user facing id copied from v, so they are not
considered as equal when used as hash key.
We may skip this test but it's better to keep all Tinkerpop tests passed as
GraphDB provider I think.
So instead, I will propose to change so that we can add a capability to swap
TraverserSet as needed.
The change should be simple,
1. ExpandableIterator should have constructor like ExpandableIterator(final
Step<S, ?> hostStep, final TraverserSet<S> traverserSet) and use the
traverserSet as its own traverserSet value.
2. AbstractStep should have construct like AbstractStep(final Traversal.Admin
traversal, final Supplier<TraverserSet<S>> traverserSetSupplier) and use
traverserSetSuppler.get() for all places that currently we instantiate new
TraverserSet.
Also this supplier.get() may be passed when AbstractStep instantiates
ExpandableIterator.
So still GraphDB provider needs to extends all Steps that deals with
TraverserSet and overwrite their constructor to have their own
traverserSetSupplier, but after that they can freely use their own
TraverserSet, so the logic how the key of TraverserSet is determined is up to
GraphDB provider.
Or if we add some helper method like getTraverserSetSupplier under, for
instance, Graph class, then instead of extending all steps we can just override
that method under our own Graph class. But I am not sure which is better in
this case, but either way the goal is the same.
Any thoughts or objections on this idea ?
was:
Currently in many TinkerPop steps, TraverserSet is internally created and used.
However GraphDB provider may want to use their own TraverserSet to change the
logic how it populates an inner Map.
Just let me give one example
Say internally we have an internal representation for each element and want to
use it for hash key which won't be exposed to client when the result is
returned.
We can simply achieve this by using internal id as a hashCode, but we can't
overwrite ElementHelper's behavior so first we tried overriding
Element#hashCode but after that we saw that this test effectively fails.
[https://github.com/apache/tinkerpop/blob/cff4c161615f2b50bda27b6ba523c7f52b833532/gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/structure/util/detached/DetachedVertexTest.java#L75]
Here v is our own custom vertex instance which uses internal id for hashCode
but DetachedVertex just uses a user facing id copied from v, so they are not
considered as equal when used as hash key.
We may skip this test but it's better to keep all Tinkerpop tests passed as
GraphDB provider I think.
So instead, I will propose to change so that we can add a capability to swap
TraverserSet as needed.
The change should be simple,
1. ExpandableIterator should have constructor like ExpandableIterator(final
Step<S, ?> hostStep, final TraverserSet<S> traverserSet) and use the
traverserSet as its own traverserSet value.
2. AbstractStep should have construct like AbstractStep(final Traversal.Admin
traversal, final Supplier<TraverserSet<S>> traverserSetSupplier) and use
traverserSetSuppler.get() for all places that currently we instantiate new
TraverserSet.
Also this supplier.get() may be passed when AbstractStep instantiates
ExpandableIterator.
So still GraphDB provider needs to extends all Steps that deals with
TraverserSet and overwrite their constructor to have their own
traverserSetSupplier, but after that they can freely use their own
TraverserSet, so the logic how the key of TraverserSet is determined is up to
GraphDB provider.
Or if we add some helper method like getTraverserSetSupplier under, for
instance, Graph class, then instead of extending all steps we can just override
that method under our own Graph class. But I am not sure which is better in
this case, but either way the goal is the same.
Any thoughts or objections on this idea ?
> TraverserSet should be extendable for GraphDB provider
> ------------------------------------------------------
>
> Key: TINKERPOP-2396
> URL: https://issues.apache.org/jira/browse/TINKERPOP-2396
> Project: TinkerPop
> Issue Type: Improvement
> Components: process
> Reporter: redtree
> Priority: Minor
>
> Currently in many TinkerPop steps, TraverserSet is internally created and
> used.
> However GraphDB provider may want to use their own TraverserSet to change
> the logic how it populates an inner Map.
> Just let me give one example
> Say internally we have a different representation of id (which won't be
> exposed to client when the result is returned) for each element and want to
> use it for hash key.
> Because we can't overwrite ElementHelper's behavior so first we tried
> overriding Element#hashCode but after that we saw that this test effectively
> fails.
>
> [https://github.com/apache/tinkerpop/blob/cff4c161615f2b50bda27b6ba523c7f52b833532/gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/structure/util/detached/DetachedVertexTest.java#L75]
> Here v is our own custom vertex instance which uses internal id for hashCode
> but DetachedVertex just uses a user facing id copied from v, so they are not
> considered as equal when used as hash key.
> We may skip this test but it's better to keep all Tinkerpop tests passed as
> GraphDB provider I think.
> So instead, I will propose to change so that we can add a capability to swap
> TraverserSet as needed.
> The change should be simple,
> 1. ExpandableIterator should have constructor like ExpandableIterator(final
> Step<S, ?> hostStep, final TraverserSet<S> traverserSet) and use the
> traverserSet as its own traverserSet value.
> 2. AbstractStep should have construct like AbstractStep(final
> Traversal.Admin traversal, final Supplier<TraverserSet<S>>
> traverserSetSupplier) and use traverserSetSuppler.get() for all places that
> currently we instantiate new TraverserSet.
> Also this supplier.get() may be passed when AbstractStep instantiates
> ExpandableIterator.
> So still GraphDB provider needs to extends all Steps that deals with
> TraverserSet and overwrite their constructor to have their own
> traverserSetSupplier, but after that they can freely use their own
> TraverserSet, so the logic how the key of TraverserSet is determined is up to
> GraphDB provider.
> Or if we add some helper method like getTraverserSetSupplier under, for
> instance, Graph class, then instead of extending all steps we can just
> override that method under our own Graph class. But I am not sure which is
> better in this case, but either way the goal is the same.
> Any thoughts or objections on this idea ?
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