[Building Sakai] ContentHosting cache?

[Jim Eng]

That cache had some problems, as I recall, and was not being used by the time I worked on CHS issues.  But I can't tell you what the problems were.   

CHS does a lot of thread-local caching (or did when I last looked) of data relevant to processing the user's current request.  It also saves too much info in session state, which has the effect of caching info for a specific user across requests.  As with many things in Sakai, the permissions and volatility of data make caching difficult.  CHS needs to answer questions for different users in different ways depending on the specific users' permissions, group membership, etc.  And inappropriate caching (as in session state) can result in a user being denied access to resources when permissions or availability change.  I suspect some of these issues may have come up with that early attempt at caching in CHS.

I'm just saying it's not as easy as turning on caching. 

Jim


On Aug 15, 2010, at 4:39 AM, David Horwitz wrote:

>  Hi All,
> 
> While reviewing our production cache performance and pondering where 
> Sakai migh benefit from more caches I discovered that ContentHosting has 
> a cache but that its switched off by default.  I can't seem to find any 
> documentation on this cache and wonder if there is a reason why it 
> shouldn't be switched on?
> 
> For the record it can be switched on with:
> 
> caching at org.sakaiproject.content.api.ContentHostingService=true
> 
> 
> Regards
> 
> David
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