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From "Joerg Schaible (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DBCP-358) Equals implementations in DelegatingXxx classes are not symmetric
Date Tue, 03 May 2011 00:46:03 GMT

    [ https://issues.apache.org/jira/browse/DBCP-358?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13027967#comment-13027967
] 

Joerg Schaible commented on DBCP-358:
-------------------------------------

Thinking about it ... if I create a *temporary* connection instance and use it as key in a
WeakHashMap, it does not make too much sense either. OTOH, if I use an unwrapped connection
as key that is also part of the WeakHashMap's value (the xaResource), the WeakHashMap is also
useless. So, what do we try to solve with the WeakHashMap for the XAResources here?

> Equals implementations in DelegatingXxx classes are not symmetric
> -----------------------------------------------------------------
>
>                 Key: DBCP-358
>                 URL: https://issues.apache.org/jira/browse/DBCP-358
>             Project: Commons Dbcp
>          Issue Type: Bug
>    Affects Versions: 1.2, 1.2.2, 1.3, 1.4
>            Reporter: Phil Steitz
>             Fix For: 1.3.1, 1.4.1
>
>
> For reasons unclear to me, DelegatingConnection, DelegatingStatement, PoolGuardConnectionWrappers
and other DBCP classes implement equals so that the wrapping class is considered equal to
its innermost delegate JDBC object.  This makes equals asymmetric when applied to a wrapper
and its wrapped JDBC object - wrapper.equals(delegate) returns true, but delegate.equals(wrapper)
will in general return false.
> I am pretty sure that DBCP itself does not rely on this bugged behavior, so I am inclined
to fix it, making equals an equivalence relation on wrapper instances, with two considered
equal iff their innermost delegates are equal.  I can't imagine use cases where the bugged
behavior is required.  Can anyone else?

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