/// <summary>
/// Updates the view by making the query over the Native Store (i.e. the query is handled by the stores SPARQL implementation).
/// </summary>
protected override void UpdateViewInternal()
{
try
{
Object results = ((INativelyQueryableStore)_store).ExecuteQuery(_q.ToString());
if (results is IGraph)
{
DetachEventHandlers(_triples);
IGraph g = (IGraph)results;
foreach (Triple t in g.Triples)
{
_triples.Add(t.CopyTriple(this));
}
AttachEventHandlers(_triples);
}
else
{
DetachEventHandlers(_triples);
_triples = ((SparqlResultSet)results).ToTripleCollection(this);
AttachEventHandlers(_triples);
}
LastError = null;
RaiseGraphChanged();
}
catch (RdfQueryException queryEx)
{
LastError = new RdfQueryException("Unable to Update a SPARQL View as an error occurred in processing the Query - see Inner Exception for details", queryEx);
}
}
/// <summary>
/// Updates the view by making the SPARQL Query in-memory over the relevant Triple Store.
/// </summary>
protected override void UpdateViewInternal()
{
try
{
var processor = new LeviathanQueryProcessor((IInMemoryQueryableStore)_store);
var results = processor.ProcessQuery(_q);
if (results is IGraph g)
{
// Note that we replace the existing triple collection with an entirely new one as otherwise nasty race conditions can happen
// This does mean that while the update is occurring the user may be viewing a stale graph
DetachEventHandlers(_triples);
TreeIndexedTripleCollection triples = new TreeIndexedTripleCollection();
foreach (Triple t in g.Triples)
{
triples.Add(t.CopyTriple(this));
}
_triples = triples;
AttachEventHandlers(_triples);
}
else
{
// Note that we replace the existing triple collection with an entirely new one as otherwise nasty race conditions can happen
// This does mean that while the update is occurring the user may be viewing a stale graph
DetachEventHandlers(_triples);
_triples = ((SparqlResultSet)results).ToTripleCollection(this);
AttachEventHandlers(_triples);
}
LastError = null;
RaiseGraphChanged();
}
catch (RdfQueryException queryEx)
{
LastError = new RdfQueryException("Unable to Update a SPARQL View as an error occurred in processing the Query - see Inner Exception for details", queryEx);
}
}
/// <summary>
/// Processes a SPARQL Query asynchronously invoking the relevant callback when the query completes
/// </summary>
/// <param name="query">SPARQL QUery</param>
/// <param name="rdfCallback">Callback for queries that return a Graph</param>
/// <param name="resultsCallback">Callback for queries that return a Result Set</param>
/// <param name="state">State to pass to the callback</param>
/// <remarks>
/// In the event of a success the appropriate callback will be invoked, if there is an error both callbacks will be invoked and passed an instance of <see cref="AsyncError"/> which contains details of the error and the original state information passed in.
/// </remarks>
public void ProcessQuery(SparqlQuery query, GraphCallback rdfCallback, SparqlResultsCallback resultsCallback, Object state)
{
Graph g = new Graph();
SparqlResultSet rset = new SparqlResultSet();
ProcessQueryAsync d = new ProcessQueryAsync(this.ProcessQuery);
d.BeginInvoke(new GraphHandler(g), new ResultSetHandler(rset), query, r =>
{
try
{
d.EndInvoke(r);
if (rset.ResultsType != SparqlResultsType.Unknown)
{
resultsCallback(rset, state);
}
else
{
rdfCallback(g, state);
}
}
catch (RdfQueryException queryEx)
{
if (rdfCallback != null)
{
rdfCallback(null, new AsyncError(queryEx, state));
}
if (resultsCallback != null)
{
resultsCallback(null, new AsyncError(queryEx, state));
}
}
catch (Exception ex)
{
RdfQueryException queryEx = new RdfQueryException("Unexpected error while making an asynchronous query, see inner exception for details", ex);
if (rdfCallback != null)
{
rdfCallback(null, new AsyncError(queryEx, state));
}
if (resultsCallback != null)
{
resultsCallback(null, new AsyncError(queryEx, state));
}
}
}, state);
}
/// <summary>
/// Callback for when asychronous invalidation completes.
/// </summary>
/// <param name="result">Async call results.</param>
private void InvalidateViewCompleted(IAsyncResult result)
{
try
{
_async.EndInvoke(result);
// If we've been further invalidated then need to re-query
if (_requiresInvalidate)
{
InvalidateView();
_requiresInvalidate = false;
}
}
catch (Exception ex)
{
// Ignore errors
LastError = new RdfQueryException("Unable to complete update of SPARQL View, see inner exception for details", ex);
}
}
/// <summary>
/// Invalidates the View causing it to be updated.
/// </summary>
private void InvalidateView()
{
Task.Factory.StartNew(UpdateViewInternal).ContinueWith(antecedent =>
{
if (antecedent.IsFaulted)
{
LastError = new RdfQueryException(
"Unable to complete update of SPARQL View, see inner exception for details",
antecedent.Exception);
}
else
{
if (_requiresInvalidate)
{
InvalidateView();
_requiresInvalidate = false;
}
}
});
}
