[jboss-jira] [JBoss JIRA] Commented: (JASSIST-133) The classpool cache overrides the search order which is expected based on ClassPath objects order

[Mooky Grand (JIRA)]

    [ https://jira.jboss.org/browse/JASSIST-133?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12559652#action_12559652 ] 

Mooky Grand commented on JASSIST-133:
-------------------------------------

Please note that in step 3 I explicitly change the search order of the ClassPool by adding another ClassPath instance. I think in such a case it's fair to expect that a different CtClass will be returned.

What happens in my case is that the first version of the CtClass is not added to the cache explicitly. It's added because it's a dependency of some other CtClass.

BTW, I found a problem with the first suggested work around (not sure if it's another bug or not). It caused me to get compilation errors for modifications that previously worked (more specifically using private fields that appeared in the original byte codes). Therefore,  I only use the second option of calling makeClass.

If you choose to leave the method as is, then I wonder if makeClass is really equivalent with what I previously did (especially in terms of overhead - memory & CPU).

> The classpool cache overrides the search order which is expected based on ClassPath objects order
> -------------------------------------------------------------------------------------------------
>
>                 Key: JASSIST-133
>                 URL: https://jira.jboss.org/browse/JASSIST-133
>             Project: Javassist
>          Issue Type: Bug
>    Affects Versions: 3.13.0.GA
>         Environment: Reproduced on Windows XP (32) + Java 1.6.0_16.
>            Reporter: Mooky Grand
>            Assignee: Shigeru Chiba
>
> 1. create a class pool that contains a class path from which you can get CtClass for class "A".
> 2. use the class pool to get the CtClass of class "B" which depends on class "A" (e.g. one of the return values of a method in class "B" is "A").
> 3. insert a new class path to the beginning of the class pool (ClassPoll.insertClassPath) that also contains the byte array for class "A"
> 4. Call ClassPool.get in order to get class "A"
> Expected:
> 1. A CtClass will be returned.
> 2. The returned CtClass will be based on the byte array from the ClassPath object which was added in step 3 above.
> Actual:
> 1. A CtClass will be returned.
> 2. The returned CtClass will be based on the byte array from the ClassPath object which was added in step 1 above.
> Reason:
> The cache used by ClassPool instances has no concept of ClassPath order. Once a CtClass is added to this cache, it will override the expected search order among ClassPath objects.
> Suggested Work Around:
> 1. using classPool.getAndRename(<className>, <className>).
> 2. using makeClass with ByteArrayInputstream for the byte array you wish to use.

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