Re: [Springframework-developer] C3P0NativeJdbcExtractor problem with Hibernate 3.1.2

[Juergen H. <ju...@in...>]

This is caused by Hibernate 3.1's introduction of its
"BorrowedConnectionProxy". Any Connection returned from a Hibernate =
Session
is now such a proxy instead of the target Connection. Of course our
NativeJdbcExtractor doesn't know how to deal with this, since it =
operates on
actual connection pool handles.

This is not a Spring issue in the first place, of course: It will affect =
any
code calling Session.connection() and expecting to cast it to a driver =
impl
class - or usually, first connection pool impl class, then driver impl
class.

I've just checked the Hibernate implementation of that
BorrowedConnectionProxy: There is no direct way of retrieving the =
underlying
target Connection; it's simply not been considered. This is a pain, of
course, but we can do something about it: apply the same =
DatabaseMetaData
trick that our SimpleNativeJdbcExtractor uses.

So what I've done is refined our NativeJdbcExtractorAdapter base class: =
It
first tries the subclass's extraction process. If that failed - that is,
returned the same Connection handle as passed in - we'll simply call
con.getMetaData().getConnection() and retry the subclass's extraction
process.

Since Hibernate doesn't wrap the Connection exposed by the =
DatabaseMetaData
object, we'll get access to the actual pool Connection and are able to =
apply
our C3P0 / Commons DBCP / etc extraction rules. This will also work for =
all
other sorts of simple proxying, for example by other persistence =
providers.

The NativeJdbcExtractorAdapter refinement will be released in Spring 2.0 =
M4
and also (a bit later) in Spring 1.2.8. For the time being, simply =
subclass
your extractor and call con.getMetaData().getConnection() before =
attempting
to cast for C3P0ProxyConnection (or the like).

Juergen
=20

-----Original Message-----
From: spr...@li...
[mailto:spr...@li...] On Behalf =
Of
Magnus Heino
Sent: Monday, March 13, 2006 2:01 PM
To: spr...@li...
Subject: [Springframework-developer] C3P0NativeJdbcExtractor problem =
with
Hibernate 3.1.2

Hi.

I'm not sure if this is a bug, new feature, or if it's me just being =
dumb :)

I have a class that extends JdbcDAOSupport. I'm using
com.mchange.v2.c3p0.ComboPooledDataSource,
org.springframework.orm.hibernate3.LocalSessionFactoryBean and
org.springframework.jdbc.support.nativejdbc.C3P0NativeJdbcExtractor.

I do this:

conn =3D (OracleConnection) getJdbcTemplate()
=09
.getNativeJdbcExtractor().getNativeConnection(
=09
DataSourceUtils.getConnection(getDataSource()));

in the c3p0jdbcextractor, this instanceof

protected Connection doGetNativeConnection(Connection con) throws
SQLException {
		if (con instanceof C3P0ProxyConnection) {


returns true when using hibernate 3.0.5. When using 3.1.2 however, "con"
looks like this:

con=3D $Proxy19  (id=3D196)
	h=3D BorrowedConnectionProxy  (id=3D253)
		connectionManager=3D ConnectionManager  (id=3D256)
			batcher=3D BatchingBatcher  (id=3D261)
			borrowedConnection=3D $Proxy19  (id=3D196)
			callback=3D JDBCContext  (id=3D265)
			connection=3D NewProxyConnection  (id=3D268)
			factory=3D SessionFactoryImpl  (id=3D269)
			interceptor=3D EmptyInterceptor  (id=3D275)
			isClosed=3D false
			releaseMode=3D ConnectionReleaseMode  (id=3D278)
			wasConnectionSupplied=3D false
		useable=3D true

the "con" when used hibernate 3.0.5 is now in
con->h->connectionManager->connection

Is this a configuration error, hibernate bug, C3P0NativeJdbcExtractor =
bug,
or what?

--

  /Magnus Heino


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