Bug 88287; add blocking style GetDataSource method so callers can ensure they use an already registered data source; r=sgehani, sr=waterson

rdf/base/idl/nsIRDFService.idl

@@ -135,6 +135,11 @@ interface nsIRDFService : nsISupports {
     // new data source. If construction is successful, the data source will
     // be initialized via <tt>nsIRDFDataSource::Init()</tt>.
     nsIRDFDataSource GetDataSource(in string aURI);
+
+    // Same as GetDataSource, but if a remote/XML data source needs to be
+    // constructed, then this method will issue a <b>blocking</b> Refresh
+    // call on that data source.
+    nsIRDFDataSource GetDataSourceBlocking(in string aURI);
 };
 
 %{C++

rdf/base/src/nsRDFService.cpp

@@ -125,6 +125,7 @@ public:
     // Implementation methods
     nsresult RegisterLiteral(nsIRDFLiteral* aLiteral, PRBool aReplace = PR_FALSE);
     nsresult UnregisterLiteral(nsIRDFLiteral* aLiteral);
+    nsresult GetDataSource(const char *aURI, PRBool aBlock, nsIRDFDataSource **aDataSource );
 };
 
 static RDFServiceImpl* gRDFService; // The one-and-only RDF service
@@ -1153,6 +1154,22 @@ RDFServiceImpl::UnregisterDataSource(nsIRDFDataSource* aDataSource)
 
 NS_IMETHODIMP
 RDFServiceImpl::GetDataSource(const char* aURI, nsIRDFDataSource** aDataSource)
+{
+    // Use the other GetDataSource and ask for a non-blocking Refresh.
+    // If you wanted it loaded synchronously, then you should've tried to do it
+    // yourself, or used GetDataSourceBlocking.
+    return GetDataSource( aURI, PR_FALSE, aDataSource );
+}
+
+NS_IMETHODIMP
+RDFServiceImpl::GetDataSourceBlocking(const char* aURI, nsIRDFDataSource** aDataSource)
+{
+    // Use GetDataSource and ask for a blocking Refresh.
+    return GetDataSource( aURI, PR_TRUE, aDataSource );
+}
+
+nsresult
+RDFServiceImpl::GetDataSource(const char* aURI, PRBool aBlock, nsIRDFDataSource** aDataSource)
 {
     NS_PRECONDITION(aURI != nsnull, "null ptr");
     if (! aURI)
@@ -1213,9 +1230,6 @@ RDFServiceImpl::GetDataSource(const char* aURI, nsIRDFDataSource** aDataSource)
         ds = do_CreateInstance(kRDFXMLDataSourceCID, &rv);
         if (NS_FAILED(rv)) return rv;
 
-        // Start the datasource load asynchronously. If you wanted it
-        // loaded synchronously, then you should've tried to do it
-        // yourself.
         nsCOMPtr<nsIRDFRemoteDataSource> remote(do_QueryInterface(ds));
         NS_ASSERTION(remote, "not a remote RDF/XML data source!");
         if (! remote) return NS_ERROR_UNEXPECTED;
@@ -1223,7 +1237,7 @@ RDFServiceImpl::GetDataSource(const char* aURI, nsIRDFDataSource** aDataSource)
         rv = remote->Init(aURI);
         if (NS_FAILED(rv)) return rv;
 
-        rv = remote->Refresh(PR_FALSE);
+        rv = remote->Refresh(aBlock);
         if (NS_FAILED(rv)) return rv;
     }