Okay sure but you can't see how this thread has been a bit confusing? You've mixed two features you'd like to implement, multi-threaded transactions and an API rewrite, with an unrelated caching problem. You're also talking about problems with when commits occur that I haven't yet been able to tie into this discussion. All of these things should be separate conversations.
I'm trying to discuss and understand what you're proposing and then you start up on some HotWax rant. What you seem to miss here is that you're the one shutting down discussion not Jacopo or I. Lately you seem to have decided that it's okay to write a couple of sentences proposing major changes and then throw your arms up when anyone asks for more detail and spend the next few months complaining about how the project is dead and won't innovate. If you don't want to fully discuss and articulate your ideas then keep them in the drawer and save us all some time. Regards Scott On 27/08/2014, at 9:47 am, Adrian Crum <[email protected]> wrote: > >> On 8/27/2014 9:30 AM, Scott Gray wrote: > >>> You're yet to describe the problem with using ThreadLocal variables. > > > >>>>>>>>> On 25/08/2014, at 10:51 am, Adrian Crum > >>>>>>>>> <[email protected]> wrote: > >>>>>>>>>> A Delegator instance always references the transaction it is > >>>>>>>>>> running in. > >>>>>>>>>> > >>>>>>>>>> The advantage to this approach is we gain the ability to hand off > >>>>>>>>>> Delegator instances to other threads. Other threads can even > >>>>>>>>>> commit/rollback a transaction: > >>>>>>>>>> > >>>>>>>>>> Transaction tx = delegator.getTransaction(); > >>>>>>>>>> tx.commit(); > > > Adrian Crum > Sandglass Software > www.sandglass-software.com > > On 8/27/2014 9:43 AM, Scott Gray wrote: >> Okay whatever, thanks for wasting my time with this thread. >> >> On 27/08/2014, at 9:39 am, Adrian Crum <[email protected]> >> wrote: >> >>> I have, but no one is paying attention. Perhaps if I worked for Hotwax, I >>> could get someone to pay attention. >>> >>> I'm done. >>> >>> Adrian Crum >>> Sandglass Software >>> www.sandglass-software.com >>> >>> On 8/27/2014 9:30 AM, Scott Gray wrote: >>>> You're yet to describe the problem with using ThreadLocal variables. >>>> >>>>>>> If you read the Jira issue, I point out another problem with this >>>>>>> clunky implementation - calling "commit" doesn't really commit the >>>>>>> transaction. That is why we end up with invalid data in the entity >>>>>>> cache - because developers are fooled into thinking the "commit" calls >>>>>>> in Delegator code actually commit the data, but they don't. >>>> >>>> This is the only problem you've described so far and I say it has nothing >>>> to do with our transaction management, it's because the cache isn't >>>> transaction aware. I can't understand what changes you could be >>>> suggesting that would solve that problem for the entity cache? >>>> >>>> I've read the ticket now and realize I'm just playing Adam's role. Please >>>> reconsider using Synchronization or XAResource. >>>> >>>> Regards >>>> Scott >>>> >>>> On 27/08/2014, at 2:01 am, Adrian Crum >>>> <[email protected]> wrote: >>>> >>>>> That doesn't solve the problem with using ThreadLocal variables. >>>>> >>>>> Adrian Crum >>>>> Sandglass Software >>>>> www.sandglass-software.com >>>>> >>>>> On 8/26/2014 11:06 PM, Scott Gray wrote: >>>>>> I don't think that's an issue with our transaction handling, it's simply >>>>>> a problem that the cache isn't transaction aware. >>>>>> >>>>>> If the cache were to be transaction aware it would need to implement the >>>>>> XAResource interface or perhaps even the simpler Synchronization >>>>>> interface and push cache entries to the global cache only upon commit or >>>>>> discard them on rollback. I'm loathe to suggest XAResource because we >>>>>> don't implement it properly in >>>>>> GenericXaResource/ServiceXaWrapper/DebugXaWrapper and it breaks some >>>>>> transaction managers (Atomikos is the only one I've tried). I have a >>>>>> strong feeling it could be implemented using the Synchronization >>>>>> interface without too much trouble though. >>>>>> >>>>>> Regards >>>>>> Scott >>>>>> >>>>>> On 26/08/2014, at 9:46 pm, Adrian Crum >>>>>> <[email protected]> wrote: >>>>>> >>>>>>> The concepts of "suspend" and "resume" are implemented by a ThreadLocal >>>>>>> stack. A "suspend" pushes the current transaction on the stack, and a >>>>>>> "resume" pops a transaction off the stack. >>>>>>> >>>>>>> If you read the Jira issue, I point out another problem with this >>>>>>> clunky implementation - calling "commit" doesn't really commit the >>>>>>> transaction. That is why we end up with invalid data in the entity >>>>>>> cache - because developers are fooled into thinking the "commit" calls >>>>>>> in Delegator code actually commit the data, but they don't. The >>>>>>> transaction is committed by the first bit of code that began the >>>>>>> transaction - either a request event or a service invocation. >>>>>>> >>>>>>> This is an arcane problem and it is difficult to describe, but I will >>>>>>> try to diagram it: >>>>>>> >>>>>>> Request Event >>>>>>> Service Dispatcher >>>>>>> Begin Transaction (actual begin) >>>>>>> Begin Service >>>>>>> Some service logic >>>>>>> Delegator calls "commit" - nothing happens >>>>>>> Delegator puts uncommitted values in cache >>>>>>> More service logic >>>>>>> Delegator calls "commit" - nothing happens >>>>>>> Delegator puts uncommitted values in cache >>>>>>> End Service >>>>>>> Commit Transaction (actual commit) >>>>>>> Return service results to event handler >>>>>>> >>>>>>> If something goes wrong in the service and the transaction is rolled >>>>>>> back, the uncommitted values in the cache are still there! >>>>>>> >>>>>>> You really have to spend time in Entity Engine code to fully appreciate >>>>>>> how awful the transaction implementation really is. >>>>>>> >>>>>>> My approach keeps a Transaction reference in the Delegator. Instead of >>>>>>> calling the fake "commit", the Delegator notifies the Transaction about >>>>>>> changed values. The Transaction saves the changed values locally. After >>>>>>> the transaction is committed, the Transaction instance copies the saved >>>>>>> values to the cache. >>>>>>> >>>>>>> If you look at my previous code fragment, there will be no more >>>>>>> "suspend" or "resume" - if you want a new transaction, you just get >>>>>>> another instance and use it. >>>>>>> >>>>>>> Adrian Crum >>>>>>> Sandglass Software >>>>>>> www.sandglass-software.com >>>>>>> >>>>>>> On 8/26/2014 9:02 PM, Scott Gray wrote: >>>>>>>> Okay so I guess I don't really understand what you're suggesting, or >>>>>>>> how it really differs much from what we have now. It's also not clear >>>>>>>> what your suggested API changes have to do with the ThreadLocal usages? >>>>>>>> >>>>>>>> Thanks >>>>>>>> Scott >>>>>>>> >>>>>>>> On 26/08/2014, at 3:22 pm, Adrian Crum >>>>>>>> <[email protected]> wrote: >>>>>>>> >>>>>>>>> Just use the Delegator factory. >>>>>>>>> >>>>>>>>> Adrian Crum >>>>>>>>> Sandglass Software >>>>>>>>> www.sandglass-software.com >>>>>>>>> >>>>>>>>> On 8/26/2014 2:43 PM, Scott Gray wrote: >>>>>>>>>> Hi Adrian, >>>>>>>>>> >>>>>>>>>> I'll probably have plenty of questions, but the first that comes to >>>>>>>>>> mind is: how would you use a delegator outside of a transaction with >>>>>>>>>> this approach? >>>>>>>>>> >>>>>>>>>> Thanks >>>>>>>>>> Scott >>>>>>>>>> >>>>>>>>>> On 25/08/2014, at 10:51 am, Adrian Crum >>>>>>>>>> <[email protected]> wrote: >>>>>>>>>> >>>>>>>>>>> One persistent problem with the current Entity Engine >>>>>>>>>>> implementation is the use of ThreadLocal variables in the Delegator >>>>>>>>>>> and Transactions. Their use makes it difficult (and sometimes >>>>>>>>>>> impossible) to fix Entity Engine bugs. They also make it impossible >>>>>>>>>>> to multi-thread a Delegator instance. >>>>>>>>>>> >>>>>>>>>>> Here is what I have had percolating in my head the last few months: >>>>>>>>>>> >>>>>>>>>>> Transaction tx = TransactionFactory.newTransaction(); >>>>>>>>>>> Delegator delegator = tx.getDelegator("default"); >>>>>>>>>>> // Do stuff with delegator >>>>>>>>>>> Transaction nestedTx = TransactionFactory.newTransaction(); >>>>>>>>>>> Delegator nestedDelegator = nestedTx.getDelegator("default"); >>>>>>>>>>> // Do stuff with nestedDelegator >>>>>>>>>>> nestedTx.commit(); >>>>>>>>>>> tx.commit(); >>>>>>>>>>> >>>>>>>>>>> A Delegator instance always references the transaction it is >>>>>>>>>>> running in. >>>>>>>>>>> >>>>>>>>>>> The advantage to this approach is we gain the ability to hand off >>>>>>>>>>> Delegator instances to other threads. Other threads can even >>>>>>>>>>> commit/rollback a transaction: >>>>>>>>>>> >>>>>>>>>>> Transaction tx = delegator.getTransaction(); >>>>>>>>>>> tx.commit(); >>>>>>>>>>> >>>>>>>>>>> After a commit, the Delegator instance is discarded. Any attempt to >>>>>>>>>>> use it after a commit throws an exception (the same is true with >>>>>>>>>>> the Transaction instance). >>>>>>>>>>> >>>>>>>>>>> Another problem is Delegator localization - which also uses >>>>>>>>>>> ThreadLocal variables. We can localize Delegator instances like >>>>>>>>>>> this: >>>>>>>>>>> >>>>>>>>>>> Transaction tx = TransactionFactory.newTransaction(); >>>>>>>>>>> Delegator delegator = tx.getDelegator("default", locale); >>>>>>>>>>> >>>>>>>>>>> Finally, the current implementation has a caching problem: >>>>>>>>>>> https://issues.apache.org/jira/browse/OFBIZ-5534 >>>>>>>>>>> >>>>>>>>>>> With the new design, the Delegator instance, Transaction instance, >>>>>>>>>>> and entity cache are tightly coupled - so that problem is easy to >>>>>>>>>>> solve. >>>>>>>>>>> >>>>>>>>>>> What do you think? >>>>>>>>>>> >>>>>>>>>>> -- >>>>>>>>>>> Adrian Crum >>>>>>>>>>> Sandglass Software >>>>>>>>>>> www.sandglass-software.com >>>>>>>>>> >>>>>>>> >>>>>> >>>> >>
