[Mulgara-general] Connections thread safe?

[Life is hard, and then you die]

On Tue, Feb 26, 2008 at 03:16:38PM -0600, Paul Gearon wrote:
> On Tue, Feb 26, 2008 at 1:32 PM, Alex Hall <alexhall at revelytix.com> wrote:
> > Are Connections in Mulgara thread-safe?  I am writing an abstraction
> >  layer on top of Mulgara to represent ontology models, and each "model"
> >  needs to have a Connection to the server that it uses to execute queries
> >  to get ontology metadata, list classes, etc.
> >
> >  Since the ConnectionFactory caches the Connections that it creates, if
> >  the models all share the same factory then they will wind up using the
> >  same Connection object.  This could possibly result in multiple,
> >  overlapping commands being executed on the same session from different
> >  threads.  Is this OK, or should I ensure that each model gets its own
> >  Connection instance?
> 
> The plan was to use one factory per thread.  However, now that you
> raise it, it sounds like a bad idea.  I should probably put in some
> TLS so that a shared factory will hand out new Connections for new
> threads.

How about separating the concepts of factory and pooling: let the
ConnectionFactory be just that, a factory, which always creates a new
connection when asked, and create a ConnectionPool (that take a
ConnectionFactory as a parameter) which manages a pool of connections
and which uses a check-out/check-in approach (maybe use commons-pool
for this).


  Cheers,

  Ronald