Hello,
We've been using OJB for well over a year now, and everyone on our team
is very satisfied with this wonderful tool. Thanks goes out to every
developer for all your hard work.
Today however we ran into a feature that until now we overlooked.
Please consider the following mapping:
<class-descriptor class="A" table="A">
<field-descriptor
id="1"
name="id"
column="ID"
jdbc-type="INTEGER"
primarykey="true"
autoincrement="true"
/>
<attribute
attribute-name="cacheable"
attribute-value="false"
/>
</class-descriptor>
For the above mapping, reading an object twice inside the the same
transaction returns two different instances. Note that if the class was
cacheable this would not be the case.
My question is why doesn't OJB return the same instance to various reads
of the same object within the same transaction?
This is an issue for us because the following scenario occurs in our
application:
// START OF EXAMPLE CODE
beginTransaction();
...
A instance1 = read(A.class, idOfSomeA);
tx.lock(instance1, Transaction.READ);
doSomeVerifications(instance1);
...
A instance2 = read(A.class, idOfSomeA);
tx.lock(instance2, Transaction.WRITE);
instance2.setOtherFields(someNewValue);
confirmTransaction();
// END OF EXAMPLE CODE
What happens here is that alterations made upon instance2 (including the
lock which is performed) are ignored because the transaction already has
a reference to the object in question.
Any thoughts are appreciated,
Luis Cruz
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