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From Emmanuel Lecharny <elecha...@gmail.com>
Subject Re: [ApacheDS]making interceptor chain stateless
Date Mon, 07 Nov 2011 00:14:48 GMT
On 11/6/11 9:12 PM, Kiran Ayyagari wrote:
> Hi Dev,
>
>      Currently the interceptor chain heavily depends on the current
> operation context stored in the InvocationStack as a
>      threadlocal variable, but this poses a problem for transaction
> handling (if we use threadlocal transactions then
>      two different requests might get processed by the same thread
> leading to using the same transaction)
Not sure, as a request will be fully processed before another request 
can reuse the thread.
>
>      Earlier we had one big hurdle in the form of chain re-entry to
> achieve this, but now we have almost got that removed
>      (there are still some more (<4) but will remove them in the coming days)

I have checked some of the inner operation, and there are cases where we 
need to re-enter the chain: when modifying the schema. A modification of 
the rootDSE attributeTypes value, for instance, will also lead to a 
modification of the cn=schema (or is it ou=schema ? never remember...) 
partition, and this will be done with a add or delete operation call.

We may get rid of such re-entrant operation, except that we will lose 
the logging of a revert operation in this case. That would be a great 
loss, IMO.


>
>      I would like to make the interceptor chain completely stateless by
> avoiding the use of InvocationStack, so that
>      we can inject a transaction handle directly into the OperationContext.
The chain should be stateless, I'm not sure we need the InvocationStack 
anymore, but I'm not sure this is really connected to the fact that we 
use threadLocal, or not.

Again, there is one thing which has to be taken into account before we 
remove the InvocationStack, is that we can revert a complete schema 
modification, which implies a double call to the chain (an in this case, 
I wonder if we don't need to keep the reference to the parent call in 
the second call).

To be investigated further.

-- 
Regards,
Cordialement,
Emmanuel L├ęcharny
www.iktek.com


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