[infinispan-dev] JCache implementation documentation

[cotton-ben]

> 
> Please consider taking a look at the attached plan for Test #1.
> 
> It is very simple.  A "Savings Account" is cached in Infinispan 5.3.0.A.    
> Two  transactional threads simultaneously operate (access/mutate) on the
> "Savings Account".  Transactional Thread #2 indicates via the JSR-107 API
> that is is "DIRTY_READ" intolerant (by specifying
> isolation=READ_COMMITTED). 
> It expects a pessimistic locking policy to be used by 5.3.0.A (i.e. to
> block
> @t=2 on its READ invoke).   Therefore a challenge to 5.3.0.A's capability
> is
> to demonstrate the Thread 2 blocks @t=2.  This test passes if Thread 2
> blocks @t=2)

/^ Why should there be a block? Infinispan has non-blocking reads (which IMO
is better than blocking).

At t=2 with Infinsispan, TX_THR_2 will find the credit that was in the
account before TX_THR_1 did any modifications, whatever that is.
/

*Definitely non-blocking read capability is preferred!  The problem is that
if TX_THR_2 does *any* read at t=2, it will then be reading UNCOMMITTED
data.  In the Test, TX_THR_2 explicitly specified through JCACHE API that it
wants isolation=READ_COMMITTED ... and .. it thus expects that Infinispan
will honor that isolation choice (chosen because TX_THR_2 is "DIRTY READ"
intolerant) by blocking its read attempt at t=2.  Failure to block that @t=2
access to the un-committed CREDIT has dire-consequences ... e.g. if TX_THR_1
executes rollback() on  the credit @t=1 !  OUCH.  If Infinispan does not
block TX_THR_2 read @t=2 then it proceeds as if the credit happened!  The
context of TX_THR_2 is thus physically inconsistent.  The bank's data is
corrupt.*

> 
> If you confirm this test is helpful, we will then provide a
> policy=OPTIMISTIC test for #1.  Later, at the appropriate time,  we would
> like to produce explicit tests for #2 and #3.
> 
> Infinispan-5.3.0.A1=JSR-107_TRANSACTIONS_OPTION=DIRTY_READ_INTOLERANCE_TEST.pdf
> <http://infinispan-developer-list.980875.n3.nabble.com/file/n4026915/Infinispan-5.3.0.A1%3DJSR-107_TRANSACTIONS_OPTION%3DDIRTY_READ_INTOLERANCE_TEST.pdf>  
> 
> Thanks,
> Ben
> 
> 
> 
> 
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--
Galder Zamarreño
galder@
twitter.com/galderz

Project Lead, Escalante
http://escalante.io

Engineer, Infinispan
http://infinispan.org


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