[Freeipa-devel] SASL whoami

[Rob Crittenden]

Pete Rowley wrote:
> Rob Crittenden wrote:
>> Simo Sorce wrote:
>>> On Thu, 2007-10-11 at 17:10 -0400, Rob Crittenden wrote:
>>>> The connection pool has a fairly big problem with it. When a 
>>>> connection goes away, it doesn't currently see that and returns a 
>>>> failure rather than reconnecting. These connections can go away if 
>>>> FDS restarts, for example. Or the connection times out or we're hit 
>>>> by gamma rays, who knows.
>>>>
>>>> Trying to figure out where this failure is occurring and retrying 
>>>> the operation will be fairly difficult (for every LDAP operation 
>>>> basically).
>>>>
>>>> Instead what I've tried to do is run a quick operation on the 
>>>> connection when I pull it out of the pool. If it is bad I can easily 
>>>> make a new one.
>>>>
>>>> I wanted an LDAP operation that wasn't going to stress the server at 
>>>> all. There is an extended operation whoami so you can find out who 
>>>> is authenticated on this connection.
>>>>
>>>> Using this I can see whether the connection is alive or not and it 
>>>> actually works fairly well.
>>>>
>>>> The problem is that FDS doesn't implement it, so an error is logged. 
>>>> It isn't a big deal in my mind and in fact the operation is probably 
>>>> quite swift ("Do I have this extop? Nope, return.").
>>>>
>>>> So, we have several options:
>>>>
>>>> 1. Go with my current uncommitted patch and use an unimplemented 
>>>> extop to test the connection.
>>>> 2. Go with the current uncommitted patch AND write a quickie plugin 
>>>> that does whoami.
>>>> 3. Try something else altogether, such as catching ldap.SERVER_DOWN 
>>>> everywhere and trying again.
>>>
>>> 3. FDS can restart just after your operation has happened and you are
>>> still in trouble, only you are going to add tons of unnecessary
>>> operations and still not able to retry the right one.
>>>
>>> Simo.
>>>
>>
>> I'm trying to handle the most common cases. The current code will not 
>> work. We can alternatively rebind with every request, that will also 
>> detect the loss of connectivity. That just seems like overkill.
>>
>> I'm happy with a best-effort. If FDS is restarting in the middle of 
>> things a few client errors are probably the least of our troubles.
> How about a keep alive thread that adds fresh activity on each 
> connection every minute or so and fixes up dead connections.  Then we 
> can keep this business out of the main loop.
> 

Well, it may not be a good idea to keep around authenticated connections 
as it is.

All the problems go away if I unbind() once the work is done and re-bind 
later. We still save the connection cost. Shall I go ahead and do that 
instead?

rob
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