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From "Gary Gregory (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LOG4J2-891) AbstractLifecycle should not implement equals() and hashCode()
Date Wed, 05 Nov 2014 19:49:35 GMT

    [ https://issues.apache.org/jira/browse/LOG4J2-891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14198954#comment-14198954
] 

Gary Gregory commented on LOG4J2-891:
-------------------------------------

If I take out hashCode and equals from ALC, then {{org.apache.logging.log4j.core.filter.DynamicThresholdFilterSerializationTest}}
fails because it depends on equals in DynamicThresholdFilter which depends on equals in ALC.

Thoughts? Patches?

> AbstractLifecycle should not implement equals() and hashCode()
> --------------------------------------------------------------
>
>                 Key: LOG4J2-891
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-891
>             Project: Log4j 2
>          Issue Type: Bug
>          Components: API
>    Affects Versions: 2.1
>            Reporter: Mariano Gonzalez
>
> Starting with version 2.1, the AbstractLifeCycle class (which I think was also introduced
in that version) have an implementation of equals() and hashCode() which is being inherited
by other core classes such as LoggerContext. That implementation considers two objects as
equals if they have the same LifeCycle.State, and calculates the hashCode based on that same
attribute.
> This has unwanted side effects:
> * For a class like LoggerContext, that implementation of equals() doesn't apply at all.
For example, I'm using log4j2 as the logging technology for an application container. Each
deployed application get its own LoggerContext. Those LoggerContext are not equal just because
they have the same status.
> * AbstractLifeCycle instances are no longer suitable for use in a HashSet or HashMap.
Because every instance with the same state will return the same hashCode, changes are that
many of them will end up in the same bucket. Also, because of the same reasons which make
the equals() implementation wrong, invokations to HashSet#contains(AbstractLifeCycle) might
start showing unexpected behavior.
> This was fine in 2.0.2 and I have verified these issues with the LoggerContext class.
I'm pretty sure that the same thing happens to all its subclasses. I don't think that the
state is a good attribute to determine equality or idempotency.



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