[Glass] System>>#writeLockAll: and Seaside

[Richard Sargent via Glass]

Paul DeBruicker wrote
> Hi Dale,
> 
> No I need to lock some domain objects (that, for a few minutes, should
> only be editable by User A) so other users of the Seaside app can't edit
> them while User A is editing them.  

This sounds like you need to implement an application-specific locking
strategy. In such an approach, you would lock the object using the GemStone
capabilities, then check for or insert a "lock record" associating the
object with the user, then release the GemStone lock.

When your application is finished with the object, it does much the same to
release its lock. And, of course, you need a maintenance process to delete
left-over application locks (those that have been around "too long"). 



> I was following the programming guide section 8.3 Controlling Concurrent
> Access with Locks.
> 
> 
> My problem occurred because I had nginx round-robin proxying to the gems
> and noticed that because the Seaside session moved among the gems between
> requests, User A could not unlock the objects they locked unless their
> request was randomly on the gem where they acquired the locks.  
> 
> 
> Since my earlier email I've implemented sticky sessions in nginx and can
> now lock and unlock the objects.  But that doesn't ensure that User A will
> keep the lock in the gem they are on dies.   
> 
> When the gem dies all locks are released, correct?
> 
> Is there a way to assign the lock to a global so that it could be released
> from another Gem?  If not is hte best idea to implement a lock in the
> domain model and sprinkle tests around?
> 
> 
> Thanks
> 
> Paul
> 
> 
> 
> 
> 
> GLASS mailing list wrote
>> Paul,
>> 
>> Are you talking about the writeLock acquired on the session in 
>> WAGsMutualExclusionFilter>>handleFiltered:?
>> 
>> If so, the lock is acquired such that the lock is removed once a commit 
>> or abort occurs ... or if the session crashes ...
>> 
>> These locks are held on the session object while the gem processes an 
>> http request and are used to prevent multiple gems from processing 
>> requests for the same session concurrently ... the lock is reliquished 
>> when the gem commits or aborts (or crashes) thus allowing another gem to 
>> process rquests on behalf of the session, so in this case the Seaside 
>> session is "respecting the Seaside session"....
>> 
>> Perhaps you are looking at a different use case involving session 
>> affinity or something?
>> 
>> Dale
>> 
>> On 04/27/2016 10:20 AM, PAUL DEBRUICKER via Glass wrote:
>>> Hi -
>>>
>>> It is my understanding that the read/write locks are held by the gem
>>> session.   Seaside sessions can move around among gems and also outlive
>>> gems, in the event of a gem crash.
>>>
>>>
>>> Is there a recommended way to lock objects and have them respect the
>>> Seaside session, rather than the Gem session and if not how are others
>>> doing locking with Seaside?
>>>
>>>
>>> Thanks
>>>
>>> Paul
>>> _______________________________________________
>>> Glass mailing list
>>> 

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>> 
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