[Fwd: Re: [OJB-developers] About connection pool and preparedstatement cache]

[Thomas M. <tho...@ho...>]

-------- Original Message --------
Subject: Re: [OJB-developers] About connection pool and 
preparedstatement cache
Date: Sat, 09 Mar 2002 12:04:41 +0100
From: Thomas Mahler <tho...@ho...>
To: John Wang <hw...@re...>
References: 
<Pin...@sc...> 
<000b01c1c6f4$8f354f40$5901a8c0@JWANG>

Hi John,

John Wang wrote:

 > I noticed that for a class, it  can only use the same connection, 
even for
 > different users. So when 2 users are accessing the same class 
objects, they
 > will share the same connection, and may cause some problem, right?
 >


Why should this be problematic? a PersistenceBroker handles only one
JDBC transaction at a time. If two threads (or users) are working with
the the same broker only one of them can perform transactional
operations at a time.

If two threads (or users) need to work in parallel they have to obtain
individual PersistenceBrokers. As each PersistenceBroker holds its own
Connections there is again no problem here.

What kind of problems are you thinking of?


 > In ConnectionManager.getConnectionForClassDescriptor, it will get from
 > hashmap, so it will return the same for a classdescriptor.
 >


Yes, per broker it's possible to have a dedicated Connection for each
persistent Class. but in general all classes share a default connection.


 > The preparedstatement is also cached in the StatementsforClass, which is
 > good. I am just wondering whether it can live outside of a connection.
 >



PreparedStatements depend on a active Connection. Thus before using a
cached PreparedStatement OJB always checks if the Connection is still alive.

HTH,

Thomas


 > Thanks a lot,
 > John W
 >
 >
 > ----- Original Message -----
 > From: "Georg Schneider" <ge...@me...>
 > To: <obj...@li...>
 > Sent: Friday, March 08, 2002 1:33 AM
 > Subject: [OJB-developers] dynamic proxies
 >
 >
 >
 >>Hi,
 >>
 >>I just implemented a few lines to enable dynamic proxies to also 
implement
 >>interfaces which are implemented by classes further up the inheritance
 >>hierarchy. I just added the following lines in RepositoryXmlHandler 
in the
 >>method getDynamicProxyClass:
 >>
 >>            Class[] interfaces = clazz.getInterfaces();
 >>    //added from here on
 >>    Class superClass = clazz;
 >>
 >>    while((superClass = superClass.getSuperclass()) != null) {
 >>
 >>Class[] superInterfaces = superClass.getInterfaces();
 >>
 >>Class[] combInterfaces =
 >>    new Class[interfaces.length +
 >>      superInterfaces.length];
 >>System.arraycopy(interfaces,0,combInterfaces,0,
 >>interfaces.length);
 >>System.arraycopy(superInterfaces,0,combInterfaces,
 >>interfaces.length,
 >>superInterfaces.length);
 >>interfaces = combInterfaces;
 >>    }
 >>    //end added
 >>
 >>            Class proxyClass = Proxy.getProxyClass(
 >>                    clazz.getClassLoader(), interfaces);
 >>
 >>
 >>Regards
 >>
 >>Georg
 >>
 >>
 >>_______________________________________________
 >>Objectbridge-developers mailing list
 >>Obj...@li...
 >>https://lists.sourceforge.net/lists/listinfo/objectbridge-developers
 >>
 >
 >
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 >
 >
 >
 >