public bool TryGetSingleForExport(CompositionContract exportKey, out ExportDescriptor defaultForExport)
{
ExportDescriptor[] allForExport;
if (!_partDefinitions.TryGetValue(exportKey, out allForExport))
{
lock (_thisLock)
{
if (!_partDefinitions.ContainsKey(exportKey))
{
var updatedDefinitions = new Dictionary<CompositionContract, ExportDescriptor[]>(_partDefinitions);
var updateOperation = new ExportDescriptorRegistryUpdate(updatedDefinitions, _exportDescriptorProviders);
updateOperation.Execute(exportKey);
_partDefinitions = updatedDefinitions;
}
}
allForExport = (ExportDescriptor[])_partDefinitions[exportKey];
}
if (allForExport.Length == 0)
{
defaultForExport = null;
return false;
}
// This check is duplicated in the update process- the update operation will catch
// cardinality violations in advance of this in all but a few very rare scenarios.
if (allForExport.Length != 1)
throw ThrowHelper.CardinalityMismatch_TooManyExports(exportKey.ToString());
defaultForExport = allForExport[0];
return true;
}
public bool TryGetSingleForExport(CompositionContract exportKey, out ExportDescriptor defaultForExport)
{
ExportDescriptor[] allForExport;
if (!_partDefinitions.TryGetValue(exportKey, out allForExport))
{
lock (_thisLock)
{
if (!_partDefinitions.ContainsKey(exportKey))
{
var updatedDefinitions = new Dictionary <CompositionContract, ExportDescriptor[]>(_partDefinitions);
var updateOperation = new ExportDescriptorRegistryUpdate(updatedDefinitions, _exportDescriptorProviders);
updateOperation.Execute(exportKey);
_partDefinitions = updatedDefinitions;
}
}
allForExport = (ExportDescriptor[])_partDefinitions[exportKey];
}
if (allForExport.Length == 0)
{
defaultForExport = null;
return(false);
}
// This check is duplicated in the update process- the update operation will catch
// cardinality violations in advance of this in all but a few very rare scenarios.
if (allForExport.Length != 1)
{
var ex = new CompositionFailedException(SR.Format(SR.CardinalityMismatch_TooManyExports, exportKey.ToString()));
Debug.WriteLine(SR.Diagnostic_ThrowingException, ex.ToString());
throw ex;
}
defaultForExport = allForExport[0];
return(true);
}