no. 2009/11/23 Rémi Després-Smyth <[email protected]>
> Fabio, > > There wouldn’t be two transactions on the same thread, but I’m working on a > web app, so different worker threads would be running using different > sessions. I did not think setting up a test that uses two different threads > to be necessary to test the scenario – instead, I just used two different > sessions, which is close enough to how it would work in production anyhow. > > > > I don’t think this is an invalid question to be asking. The app’s on a web > server, and concurrent requests are processed by different worker threads, > aren’t they? Setting up a test that uses two distinct threads would be > unnecessary and unreliable, since it would be difficult to ensure correct > timing between the two threads for the behaviour I want to see. As a > result, I believe the test I setup is actually quite appropriate for what I > want to check. > > > > No? > > > > Remi. > > > > *From:* Fabio Maulo [mailto:[email protected]] > *Sent:* November 21, 2009 10:48 AM > *To:* [email protected] > *Subject:* Re: [nhusers] how should optimistic concurrency using a version > field work? > > > > is that ;) > > btw what I mean, is that the tests is not well formed in many sense. > > If our friend Remi want test NH behaviour he should try to recreate a > behaviour-test using a more real scenario trying to reproduce how "things" > happens in his application. > > For example... How Remí can recreate that sequence of actions in a real app > ? > > Even if he can, how much is correct to have two opened transactions in the > same thread ? > > ... and so on... > > > > 2009/11/21 Oskar Berggren <[email protected]> > > Fabio, are you referring to the fact he assigns a string to b, instead > of to b.Prop2? I noticed, but ignored that, and it was corrected in > another mail. Or is there something else I'm missing? > > /Oskar > > > 2009/11/21 Fabio Maulo <[email protected]>: > > > Oskar, that code can't be compiled (try to compile it by eyes). > > > > 2009/11/20 Oskar Berggren <[email protected]> > >> > >> This is somewhat of a guess, but I suspect you will see the expected > >> behavior if you replace Load with Get. Or don't commit sess1 until > >> after you've modified b. > >> > >> Get fetches the object immediately, while Load returns a proxy, not > >> loading the object until you first access one of it's properties. This > >> should cause b to actually show the value committed in sess1, the way > >> your code looks now. > >> > >> /Oskar > >> > >> > >> 2009/11/20 Rémi Després-Smyth <[email protected]>: > >> > Can anyone explain optimistic locking in the context of NHibernate? > >> > (Using > >> > NHib 2.1.1.) > >> > > >> > > >> > > >> > I’ve been running tests and my results are counter-intuitive. I have > a > >> > versioned entity: > >> > > >> > > >> > > >> > > >> > > >> > <class name="Test.Entity, Test" table="tblEntity" abstract="false" > >> > optimistic-lock="version"> > >> > > >> > > >> > > >> > <id name="Id" column="scheduleId" access="property" > >> > unsaved-value="0" > >> > type="Int64"> > >> > > >> > <generator class="hilo"> > >> > > >> > <param name="table">tblHiloUId</param> > >> > > >> > <param name="column">nextHighValue</param> > >> > > >> > <param name="max_lo">100</param> > >> > > >> > </generator> > >> > > >> > </id> > >> > > >> > > >> > > >> > <version column="version" name="Version" type="Int32" > >> > unsaved-value="0" /> > >> > > >> > > >> > > >> > <property name="Prop1" column="prop1" update="false" > >> > > >> > access="property" not-null="false" type="Boolean" > >> > > >> > optimistic-lock="true" /> > >> > > >> > > >> > > >> > <property name="Prop2" column="isDefaultOverridable" > >> > > >> > access="field" not-null="true" type="String" > >> > > >> > optimistic-lock="true" /> > >> > > >> > </class> > >> > > >> > > >> > > >> > And the following test: > >> > > >> > > >> > > >> > [Test, > >> > ExpectedException(ExceptionType=typeof(StaleObjectStateException))] > >> > > >> > public void SavingUpdatesOptimisticLockShouldThrow() > >> > > >> > { > >> > > >> > var cfg = new NHibernate.Cfg.Configuration(); > >> > > >> > cfg.AddAssembly("Test"); > >> > > >> > cfg.Configure(); > >> > > >> > var sessionFactory = cfg.BuildSessionFactory(); > >> > > >> > > >> > > >> > var sess1 = sessionFactory.OpenSession(); > >> > > >> > var sess2 = sessionFactory.OpenSession(); > >> > > >> > > >> > > >> > sess1.BeginTransaction(); > >> > > >> > sess2.BeginTransaction(); > >> > > >> > > >> > > >> > // NOTE: I get the same results if I load with Lock.None > >> > > >> > // A record is loaded in the DB in test setup, assigned to m_Id > >> > > >> > var a = sess1.Load<Entity>(m_Id); > >> > > >> > var b = sess2.Load<Entity>(m_Id); > >> > > >> > > >> > > >> > a.Prop2 = "New test value, session1”; > >> > > >> > sess1.Save(a); > >> > > >> > sess1.Transaction.Commit(); > >> > > >> > > >> > > >> > b = "Another, session2"; > >> > > >> > sess2.Save(b); > >> > > >> > sess2.Transaction.Commit(); // Should throw? > >> > > >> > } > >> > > >> > > >> > > >> > After reading the docs, this is what I’d expect to see: > >> > > >> > > >> > > >> > Both instances start with version=1. When I save and commit a, I see > >> > that > >> > its version number is incremented from 1 to 2, while b still has > >> > version=1 > >> > (as I’d expect). I’d expect that the call to > sess2.Transaction.Commit() > >> > should throw, because NHibernate will determine that the record was > >> > updated > >> > since b was loaded, so optimistic concurrency issue. But it doesn’t – > b > >> > commits fine, and overwrites changes saved when a was saved. > >> > > >> > > >> > > >> > If I load explicitly selecting the lock I want, it does work as I’d > >> > expect > >> > and I get my exception. > >> > > >> > > >> > > >> > This is surprising to me. Ayende noted in a concurrency blog post > >> > > >> > ( > http://ayende.com/Blog/archive/2009/04/15/nhibernate-mapping-concurrency.aspx > ) > >> > that using a version column should result in the generated UPDATE SQL > >> > statement to compare against the version number – and if the version > >> > doesn’t > >> > match the original version, we should get a StaleObjectException. > >> > > >> > > >> > > >> > Can anyone clarify what’s going on here? > >> > > >> > > >> > > >> > Thanks. > >> > > >> > Remi. > >> > > >> > > >> > > >> > -- > >> > > >> > You received this message because you are subscribed to the Google > >> > Groups > >> > "nhusers" group. > >> > To post to this group, send email to [email protected]. > >> > To unsubscribe from this group, send email to > >> > [email protected]<nhusers%[email protected]> > . > >> > For more options, visit this group at > >> > http://groups.google.com/group/nhusers?hl=. > >> > > >> > >> -- > >> > >> You received this message because you are subscribed to the Google > Groups > >> "nhusers" group. > >> To post to this group, send email to [email protected]. > >> To unsubscribe from this group, send email to > >> [email protected]<nhusers%[email protected]> > . > >> For more options, visit this group at > >> http://groups.google.com/group/nhusers?hl=. > >> > >> > > > > > > > > -- > > Fabio Maulo > > > > -- > > > > You received this message because you are subscribed to the Google Groups > > "nhusers" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]<nhusers%[email protected]> > . > > For more options, visit this group at > > http://groups.google.com/group/nhusers?hl=. > > > > -- > > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<nhusers%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/nhusers?hl=. > > > > > -- > Fabio Maulo > > -- > > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<nhusers%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/nhusers?hl=. > > -- > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<nhusers%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/nhusers?hl=. > -- Fabio Maulo -- You received this message because you are subscribed to the Google Groups "nhusers" group. 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