As has been suggested, an RsIterator is no longer valid once its underlying
broker has been closed.
I can't find the code at the moment, so maybe I'm dreaming, but I'm pretty sure
I wrote a BrokerClosingIterator once, which could be used like so:
Iterator iter = null;
try {
broker = PersistenceBrokerFactory.defaultPersistenceBroker();
broker.beginTransaction();
iter = BrokerClosingIterator.wrap(broker.getIteratorByQuery(query), broker);
broker.commitTransaction();
} catch (PersistenceBrokerException t) {
broker.abortTransaction();
broker.close();
t.printStackTrace();
}
while (iter.hasNext()) {
Person person = (Person) iter.next();
....
some code
....
}
BrokerClosingIterator would do a broker.close() in two places: 1) when next()
consumes the last item; and 2) in a finalizer, in case we don't ever consume the
full contents of the Iterator. A problem is that it's not possible to guarantee
that the broker is closed, since the finalizer might never run. Shouldn't be
too hard to add a timeout, though - it seems that most RsIterators shouldn't
need to live very long?
-steve
Steve Clark
Technology Applications Team
Natural Resources Research Center/USGS
[EMAIL PROTECTED]
(970)226-9291
>List-Id: "OJB Users List" <ojb-user.db.apache.org>
>Subject: problem/question with getIteratorByQuery()
>Date: Thu, 30 Oct 2003 16:00:29 +0100
>Thread-Topic: problem with PB instances creation
>From: <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>
>
>Hello,
>
>I have a question/problem about the function getIteratorByQuery():
>
>Here is a code:
>
>****code****
>Iterator iter = null;
>try {
> broker = PersistenceBrokerFactory.defaultPersistenceBroker();
> broker.beginTransaction();
> iter = broker.getIteratorByQuery(query);
> broker.commitTransaction();
>} catch (PersistenceBrokerException t) {
> broker.abortTransaction();
> t.printStackTrace();
>} finally {
> broker.close();
>}
>
>while (iter.hasNext()) {
> Person person = (Person) iter.next();
> ....
> some code
> ....
>}
>****code****
>
>I have noticed that the Iterator object called iter isn't available after the
broker is closed (no iteration in the "while" statement).
>Why?
>
>My idea is to use a broker only when I need one and close it just after the
use.
>What is the solution?
>But could I write the code as below?
>
>****code****
>try {
> broker = PersistenceBrokerFactory.defaultPersistenceBroker();
> broker.beginTransaction();
> Iterator iter = broker.getIteratorByQuery(query);
> while (iter.hasNext()) {
> Person person = (Person) iter.next();
> ....
> some code
> ....
> }
> broker.commitTransaction();
>} catch (PersistenceBrokerException t) {
> broker.abortTransaction();
> t.printStackTrace();
>} finally {
> broker.close();
>}
>****code****
>
>Thanks for any help
>Sylvain
>
>---------------------------------------------------------------------
>To unsubscribe, e-mail: [EMAIL PROTECTED]
>For additional commands, e-mail: [EMAIL PROTECTED]
>
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
