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https://issues.apache.org/jira/browse/JSPWIKI-649?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12864614#action_12864614
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Magnus Lindberg commented on JSPWIKI-649:
-----------------------------------------
Hi Harry, thanks for the information on code formatting.
The scenario is, briefly, that I delete old versions of certain pages, and if
the version history is not up-to-date, I attempt to delete versions that don't
exist, and then a NoSuchVersionException is thrown.
A more detailed explanation follows:
I have written a discussion forum plugin.
Each discussion thread (i.e. each topic) is stored in a page with a certain
suffix.
Each such discussion-thread-storage-page itself contains all version history
(i.e. all comments for that thread/topic).
Hence only the very last version of such a page is needed.
So, when a new comment is added, the plugin creates a new version of the
discussion-storage-page,\\
and iterates all old page versions,\\
and deletes them.
Since the version history information provided by
{{WikiPageProvider.getVersionHistory}} is sometimes out-of-date\\
(because of the bug in {{CachingProvider}}),\\
the plugin sometimes attempts to delete a version of a page that does not exist.
This results in a {{NoSuchVersionException}} from
{{WikiPageProvider.deleteVersion}}.
(I suppose the cache is refreshed after some seconds, so this is perhaps only
an issue if two comments are added to a discussion within a short period of
time.)
***
(It seems JSPWiki 3.0 uses the {{CachingProvider}} no more, so probably only
the 2.8 branch (and other 2.X perhaps) are affected.)
***
( What I really wish to do is to 1) disable versioning for the relevant pages,
and 2) also disallow anyone from reading/editing those magic
discussion-storage-pages.
-- but these are two separate issues, I suppose; I'd better ask on the user's
mailing list in case other people are also interested. )
Regards, Magnus
> CachingProvider.deleteVersion leaves a stale m_historyCache
> -----------------------------------------------------------
>
> Key: JSPWIKI-649
> URL: https://issues.apache.org/jira/browse/JSPWIKI-649
> Project: JSPWiki
> Issue Type: Bug
> Components: Core & storage
> Affects Versions: 2.8.3, 2.8.4
> Environment: Ubuntu, Sun Java 1.6
> Reporter: Magnus Lindberg
> Priority: Minor
> Attachments: jira-jspwiki-cachingprovider-patch.txt
>
>
> Hi JSPWiki developers,
> The function
> public void deleteVersion( String pageName, int version )
> in class CachingProvider does not always update the page history cache
> appropriately.
> As a result, NoSuchVersionException:s can be thrown, if it's later assumed
> that a page exists,
> because it's present in the (cached) history list.
> Below patch should fix the bug. (Works for me.)
> Regards, Magnus
> <pre>
> Index: src/com/ecyrd/jspwiki/providers/CachingProvider.java
> ===================================================================
> --- src/com/ecyrd/jspwiki/providers/CachingProvider.java (revision
> 938415)
> +++ src/com/ecyrd/jspwiki/providers/CachingProvider.java (working copy)
> @@ -815,10 +815,10 @@
> {
> m_cache.removeEntry( pageName );
> m_textCache.removeEntry( pageName );
> - m_historyCache.removeEntry( pageName );
> }
>
> m_provider.deleteVersion( pageName, version );
> + m_historyCache.removeEntry( pageName );
> }
> }
> </pre>
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