Hi again
Just noticed that the "org.apache.clerezza.rdf.jena.storage.JenaGraphAdaptor"
does the exact same by extending
"org.apache.clerezza.rdf.core.impl.AbstractMGraph".
This means that all Graphs returned by the Jena TDB provider
(org.apache.clerezza.rdf.jena.tdb.storage.TdbTcProvider) are in fact in-memory
copies. This would not be necessary as the TdbTcProvider already ensures that a
Graph can not be opened as MGraph.
To avoid such copies one would need to refactor the JenaGraphAdaptor so that
one can create both a "JenaMGraphAdaptor" and a read-only "JenaGraphAdaptor".
JenaMGraphAdaptor.getGraph() would still need to create an in-memory copy, but
the "JenaGraphAdaptor" would allow to avoid this. TcProvider implementations
that instantiate ""JenaGraphAdaptor" would need to ensure themselves that the
underlining JenaGraph is not modified.
This is of special importance to the SingleTdbDatasetTcProvider as I am planing
to add support for exposing the "urn:x-arq:UnionGraph" via the
TcProvider.getGraph(..) method. Creating in-memory copies of the union graph
over all named models within the TDB store is not feasible.
best
Rupert
On 20.03.2012, at 08:42, Rupert Westenthaler wrote:
> Hi all,
>
> While working on the SingleTdbDatasetTcProvider I noticed that the
>
> PrivilegedMGraphWrapper#getGraph()
>
> calls
>
> public Graph getGraph() {
> return new SimpleGraph(this);
> }
>
> If I am right this causes an in-memory copy of the the wrapped MGraph to be
> created. Is there a special reason for that or should that?
>
> I would rather expect an PrivilegedGraphWrapper wrapping the graph returned
> by the wrapped MGraph to be returned. Something like.
>
> public Graph getGraph() {
> return AccessController.doPrivileged(new
> PrivilegedAction<Graph>() {
>
> @Override
> public Graph run() {
> return new
> PrivilegedGraphWrapper(wrapped.getGraph());
> }
> });
> }
>
> Maybe one would even like to have only a single PrivilegedGraphWrapper that
> is created on the first call to getGraph()
>
> best
> Rupert
>
