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https://issues.apache.org/jira/browse/CLEREZZA-686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13203429#comment-13203429
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Daniel Spicar commented on CLEREZZA-686:
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I am not sure what the intention of this patch is. As I see it you are wrapping
calls to Object.hashCode/Object.equals/Object.toString into readLocks (i.e. you
call super.hashcode). I assume what we really want, are delegation to
wrapped.hashCode etc., i.e. the hashCode method by the wrapped graph. Going
there I see the following issues:
- MGraph defines the interface for the equals method to be: "Returns true if
other represents the same mutable graph as this instance, false otherwise. It
returns true if this == other or if it s otherwise guaranteed that changes to
one of the instances are immediately reflected in the other." Given this
description I think the current equals implementation is wrong, we need to
delegate the call to the wrapped Mgraph instance.
- From my understanding the read or write locks are only needed when reading
from/writing to the wrapped MGraph. Since we ware not doing it currently, I
don't think the locks are needed in this patch.
- However when we call the methods on the wrapped instance, then we may need
them since we do not know how they are implemented there. But technically we
don't even know whether the implementation there does write access to the graph
(although I can't think of a reason why it would do that).
I think in general we want to delegate the calls to the wrapped MGraph
instance. Intuitively I would put these calls in a readlock to be sure.
Probably that will be fine. But from my knowledge the contract of these methods
does not restrict the MGraph Implementation to read access only so
theoretically there is a potential problem. But does it make sense to redefine
the contract of the MGraph interface for hashCode, toString, and equals to be
read access only? I'm not sure how this is handled elsewhere.
> LockableMGraphWrapper does not implement hashCode, equals and toString
> ----------------------------------------------------------------------
>
> Key: CLEREZZA-686
> URL: https://issues.apache.org/jira/browse/CLEREZZA-686
> Project: Clerezza
> Issue Type: Improvement
> Components: rdf.core
> Reporter: Rupert Westenthaler
> Assignee: Daniel Spicar
> Priority: Trivial
> Attachments:
> CLEREZZA-686_rdf.core-LockableMGraphWrapper-hasCode-equals-toString.patch
>
>
> LockableMGraphWrapper does not implement hashCode, equals and toString. This
> is not a big issue, because MGraphs are rarely used with sets or maps, but it
> is at least inconvenient for logging and debugging.
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