On 7/17/07, Dain Sundstrom <[EMAIL PROTECTED]> wrote:
I'm working on a fix for the back pointers bugs DBCP-11 and DBCP-217
where the Statement.getConnection() and ResultSet.getStatement()
return the wrong objects.  The fix is pretty simple; we just need to
make sure we wrap Statements and ResultSets returned from
DelegatingConnection with the matching delegating type.

+1

Anyway, I
have the fix mostly complete with a bunch of test cases, but there is
one problem...

The PerUserPoolDataSource and SharedPoolDataSource classes return the
ConnectionImpl class directly.   This class is a wrapper around the
real connection so we need to wrap returned Statements which is easy
enough.  The problem is these datasources use the
CPDSConnectionFactory which does not call passivate on the delegating
connection when the connection is returned to the pool so the
Statements owned by the DelegatingConnection aren't closed.  To make
matters worse, CPDSConnectionFactory can't call passivate anyway
because it is in a different package and the method is protected :(

At this point I'm not sure what to do.  I could fix the problem for
all DataSources except for these two, and in the future we could
rework these two to subclass PoolingDataSource.  Alternative, we
could move CPDSConnectionFactory to same package as
DelegatingConnection or make is a sublcass of some ConnectionFactory
with access to the passivate method.

I really do think these datasources should be brought in line with
the main abstractions used by the other classes, but I don't think
that is something for this release (maybe for 2.0?).


I think we should leave this alone for now and consider refactoring
for 2.0, but there is a semantic difference that we need to keep in
mind.  InstanceKeyDataSource (parent of PerUser and SharedPool)
sources connections from a ConnectionPoolDataSource.  These
datasources return connection *handles* (PooledConnection impls),
which are not the same as DelegatingConnections. The cpdsadapter
package is just there for older jdbc drivers that do not provide
ConnectionPoolDataSource implementations.  See the javadoc for
InstanceKeyDataSource and also the implementation of makeObject there.
The key difference in the contract is that InstanceKeyDataSource
implements ConnectionEventListener, so when used with a driver that
correctly supports ConnectionPoolDataSource, the connection handles
handed out to users notify the pool (actually the factory in dbcp)
when they are closed by the user.  See connectionClosed in
CPDSConnectionFactory.

Phil

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