Release the temporary graph early on (migueldeicaza#213)

migueldeicaza · web-flow · commit 803bd0de83b0 · 2018-01-17T09:24:21.000-05:00
diff --git a/Examples/ExampleCommon/ImageUtil.cs b/Examples/ExampleCommon/ImageUtil.cs
@@ -13,20 +13,19 @@ public static TFTensor CreateTensorFromImageFile (string file, TFDataType destin
 			// DecodeJpeg uses a scalar String-valued tensor as input.
 			var tensor = TFTensor.CreateString (contents);
 
-			TFGraph graph;
 			TFOutput input, output;
 
 			// Construct a graph to normalize the image
-			ConstructGraphToNormalizeImage (out graph, out input, out output, destinationDataType);
-
-			// Execute that graph to normalize this one image
-			using (var session = new TFSession (graph)) {
-				var normalized = session.Run (
-						 inputs: new [] { input },
-						 inputValues: new [] { tensor },
-						 outputs: new [] { output });
-
-				return normalized [0];
+			using (var graph = ConstructGraphToNormalizeImage (out graph, out input, out output, destinationDataType)){
+				// Execute that graph to normalize this one image
+				using (var session = new TFSession (graph)) {
+					var normalized = session.Run (
+						inputs: new [] { input },
+						inputValues: new [] { tensor },
+						outputs: new [] { output });
+					
+					return normalized [0];
+				}
 			}
 		}
 
@@ -37,7 +36,7 @@ public static TFTensor CreateTensorFromImageFile (string file, TFDataType destin
 		// This function constructs a graph of TensorFlow operations which takes as
 		// input a JPEG-encoded string and returns a tensor suitable as input to the
 		// inception model.
-		private static void ConstructGraphToNormalizeImage (out TFGraph graph, out TFOutput input, out TFOutput output, TFDataType destinationDataType = TFDataType.Float)
+		private static TFGraph ConstructGraphToNormalizeImage (out TFOutput input, out TFOutput output, TFDataType destinationDataType = TFDataType.Float)
 		{
 			// Some constants specific to the pre-trained model at:
 			// https://storage.googleapis.com/download.tensorflow.org/models/inception5h.zip
@@ -51,7 +50,7 @@ private static void ConstructGraphToNormalizeImage (out TFGraph graph, out TFOut
 			const float Mean = 117;
 			const float Scale = 1;
 
-			graph = new TFGraph ();
+			var graph = new TFGraph ();
 			input = graph.Placeholder (TFDataType.String);
 
 			output = graph.Cast (graph.Div (
@@ -64,6 +63,8 @@ private static void ConstructGraphToNormalizeImage (out TFGraph graph, out TFOut
 						size: graph.Const (new int [] { W, H }, "size")),
 					y: graph.Const (Mean, "mean")),
 				y: graph.Const (Scale, "scale")), destinationDataType);
+			
+			return graph;
 		}
 	}
 }
