[jira] Updated: (OPENJPA-1168) NPE in UUIDGenerator.initializeForType1()

["Rick Curtis (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/OPENJPA-1168?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rick Curtis updated OPENJPA-1168:
---------------------------------

    Attachment: OPENJPA-1168.patch

The patch includes a test case and the fix for this issue. 

Since this bug is a timing window, running this test case against an un-patched tree may work from time to time. Please let me know if you want me to post some more information in the test case about why I did what I did.

- Rick

> NPE in UUIDGenerator.initializeForType1()
> -----------------------------------------
>
>                 Key: OPENJPA-1168
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-1168
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: lib
>            Reporter: Rick Curtis
>            Assignee: Rick Curtis
>             Fix For: 1.3.0, 2.0.0
>
>         Attachments: OPENJPA-1168.patch
>
>
> When UUIDGenerator.createType1() is called by more than one thread at *nearly* the same time AND UUIDGenerator.createType1() wasn't called previously, a small timing window exists where a NPE will result.
> Scenario:
> Thread 1 calls UUIDGenerator.createType1() and RANDOM == null so initializeForType1() is called. While that thread is in initializeForType1(), it sets the static variable RANDOM so that value is no longer null. Now Thread 2 calls UUIDGenerator.createType1() and RANDOM is no longer null, so it proceeds to the call System.arraycopy(IP, 0, uuid, 10, IP.length);. At this point Thread 1 hasn't got to initializing IP yet, so Thread 2 gets hits a NPE.

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