Implement SafeImportGraphDefResultsHandle as a wrapper for TF_ImportGraphDefResults

src/TensorFlowNET.Core/Framework/importer.cs

@@ -62,7 +62,7 @@ namespace Tensorflow
             {
                 _PopulateTFImportGraphDefOptions(scoped_options, prefix, input_map, return_elements);
                 // need to create a class ImportGraphDefWithResults with IDisposal
-                results = c_api.TF_GraphImportGraphDefWithResults(graph, buffer.Handle, scoped_options.Handle, status.Handle);
+                results = new TF_ImportGraphDefResults(c_api.TF_GraphImportGraphDefWithResults(graph, buffer.Handle, scoped_options.Handle, status.Handle));
                 status.Check(true);
             }
 

src/TensorFlowNET.Core/Graphs/Graph.Operation.cs

@@ -33,7 +33,7 @@ namespace Tensorflow
             return c_api.TF_NewOperation(_handle, opType, opName);
         }
 
-        public Operation[] ReturnOperations(IntPtr results)
+        public Operation[] ReturnOperations(SafeImportGraphDefResultsHandle results)
         {
             TF_Operation return_oper_handle = new TF_Operation();
             int num_return_opers = 0;

src/TensorFlowNET.Core/Graphs/Graph.cs

@@ -413,7 +413,7 @@ namespace Tensorflow
             return name;
         }
 
-        public TF_Output[] ReturnOutputs(IntPtr results)
+        public TF_Output[] ReturnOutputs(SafeImportGraphDefResultsHandle results)
         {
             IntPtr return_output_handle = IntPtr.Zero;
             int num_return_outputs = 0;

src/TensorFlowNET.Core/Graphs/SafeImportGraphDefResultsHandle.cs

@@ -0,0 +1,40 @@
+/*****************************************************************************
+   Copyright 2018 The TensorFlow.NET Authors. All Rights Reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+******************************************************************************/
+
+using System;
+using Tensorflow.Util;
+
+namespace Tensorflow
+{
+    public sealed class SafeImportGraphDefResultsHandle : SafeTensorflowHandle
+    {
+        private SafeImportGraphDefResultsHandle()
+        {
+        }
+
+        public SafeImportGraphDefResultsHandle(IntPtr handle)
+            : base(handle)
+        {
+        }
+
+        protected override bool ReleaseHandle()
+        {
+            c_api.TF_DeleteImportGraphDefResults(handle);
+            SetHandle(IntPtr.Zero);
+            return true;
+        }
+    }
+}

src/TensorFlowNET.Core/Graphs/TF_ImportGraphDefResults.cs

@@ -1,18 +1,35 @@
-using System;
-using System.Runtime.InteropServices;
+/*****************************************************************************
+   Copyright 2018 The TensorFlow.NET Authors. All Rights Reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+******************************************************************************/
+
+using System;
 
 namespace Tensorflow
 {
-    public class TF_ImportGraphDefResults : DisposableObject
+    public sealed class TF_ImportGraphDefResults : IDisposable
     {
         /*public IntPtr return_nodes;
         public IntPtr missing_unused_key_names;
         public IntPtr missing_unused_key_indexes;
         public IntPtr missing_unused_key_names_data;*/
 
-        public TF_ImportGraphDefResults(IntPtr handle)
+        private SafeImportGraphDefResultsHandle Handle { get; }
+
+        public TF_ImportGraphDefResults(SafeImportGraphDefResultsHandle handle)
         {
-            _handle = handle;
+            Handle = handle;
         }
 
         public TF_Output[] return_tensors
@@ -21,7 +38,7 @@ namespace Tensorflow
             {
                 IntPtr return_output_handle = IntPtr.Zero;
                 int num_outputs = -1;
-                c_api.TF_ImportGraphDefResultsReturnOutputs(_handle, ref num_outputs, ref return_output_handle);
+                c_api.TF_ImportGraphDefResultsReturnOutputs(Handle, ref num_outputs, ref return_output_handle);
                 TF_Output[] return_outputs = new TF_Output[num_outputs];
                 unsafe
                 {
@@ -52,13 +69,7 @@ namespace Tensorflow
             }
         }
 
-        public static implicit operator TF_ImportGraphDefResults(IntPtr handle)
-            => new TF_ImportGraphDefResults(handle);
-
-        public static implicit operator IntPtr(TF_ImportGraphDefResults results)
-            => results._handle;
-
-        protected override void DisposeUnmanagedResources(IntPtr handle)
-            => c_api.TF_DeleteImportGraphDefResults(handle);
+        public void Dispose()
+            => Handle.Dispose();
     }
 }

src/TensorFlowNET.Core/Graphs/c_api.graph.cs

@@ -92,7 +92,7 @@ namespace Tensorflow
         /// <param name="status">TF_Status*</param>
         /// <returns>TF_ImportGraphDefResults*</returns>
         [DllImport(TensorFlowLibName)]
-        public static extern IntPtr TF_GraphImportGraphDefWithResults(IntPtr graph, SafeBufferHandle graph_def, SafeImportGraphDefOptionsHandle options, SafeStatusHandle status);
+        public static extern SafeImportGraphDefResultsHandle TF_GraphImportGraphDefWithResults(IntPtr graph, SafeBufferHandle graph_def, SafeImportGraphDefOptionsHandle options, SafeStatusHandle status);
 
         /// <summary>
         /// Import the graph serialized in `graph_def` into `graph`.
@@ -258,7 +258,7 @@ namespace Tensorflow
         /// <param name="num_opers">int*</param>
         /// <param name="opers">TF_Operation***</param>
         [DllImport(TensorFlowLibName)]
-        public static extern void TF_ImportGraphDefResultsReturnOperations(IntPtr results, ref int num_opers, ref TF_Operation opers);
+        public static extern void TF_ImportGraphDefResultsReturnOperations(SafeImportGraphDefResultsHandle results, ref int num_opers, ref TF_Operation opers);
 
         /// <summary>
         /// Fetches the return outputs requested via
@@ -270,7 +270,7 @@ namespace Tensorflow
         /// <param name="num_outputs">int*</param>
         /// <param name="outputs">TF_Output**</param>
         [DllImport(TensorFlowLibName)]
-        public static extern void TF_ImportGraphDefResultsReturnOutputs(IntPtr results, ref int num_outputs, ref IntPtr outputs);
+        public static extern void TF_ImportGraphDefResultsReturnOutputs(SafeImportGraphDefResultsHandle results, ref int num_outputs, ref IntPtr outputs);
 
         /// <summary>
         /// This function creates a new TF_Session (which is created on success) using

test/TensorFlowNET.UnitTest/GraphTest.cs

@@ -258,11 +258,9 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             EXPECT_EQ(0, neg.NumControlOutputs);
             EXPECT_EQ(0, neg.GetControlOutputs().Length);
 
-            // Import it again, with an input mapping, return outputs, and a return
-            // operation, into the same graph.
-            IntPtr results;
-            using (var opts = c_api.TF_NewImportGraphDefOptions())
+            static SafeImportGraphDefResultsHandle ImportGraph(Status s, Graph graph, Buffer graph_def, Operation scalar)
             {
+                using var opts = c_api.TF_NewImportGraphDefOptions();
                 c_api.TF_ImportGraphDefOptionsSetPrefix(opts, "imported2");
                 c_api.TF_ImportGraphDefOptionsAddInputMapping(opts, "scalar", 0, new TF_Output(scalar, 0));
                 c_api.TF_ImportGraphDefOptionsAddReturnOutput(opts, "feed", 0);
@@ -270,32 +268,39 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 EXPECT_EQ(2, c_api.TF_ImportGraphDefOptionsNumReturnOutputs(opts));
                 c_api.TF_ImportGraphDefOptionsAddReturnOperation(opts, "scalar");
                 EXPECT_EQ(1, c_api.TF_ImportGraphDefOptionsNumReturnOperations(opts));
-                results = c_api.TF_GraphImportGraphDefWithResults(graph, graph_def.Handle, opts, s.Handle);
+                var results = c_api.TF_GraphImportGraphDefWithResults(graph, graph_def.Handle, opts, s.Handle);
                 EXPECT_EQ(TF_Code.TF_OK, s.Code);
-            }
-
-            Operation scalar2 = graph.OperationByName("imported2/scalar");
-            Operation feed2 = graph.OperationByName("imported2/feed");
-            Operation neg2 = graph.OperationByName("imported2/neg");
-
-            // Check input mapping
-            neg_input = neg.Input(0);
-            EXPECT_EQ(scalar, neg_input.oper);
-            EXPECT_EQ(0, neg_input.index);
 
-            // Check return outputs
-            var return_outputs = graph.ReturnOutputs(results);
-            ASSERT_EQ(2, return_outputs.Length);
-            EXPECT_EQ(feed2, return_outputs[0].oper);
-            EXPECT_EQ(0, return_outputs[0].index);
-            EXPECT_EQ(scalar, return_outputs[1].oper);  // remapped
-            EXPECT_EQ(0, return_outputs[1].index);
+                return results;
+            }
 
-            // Check return operation
-            var return_opers = graph.ReturnOperations(results);
-            ASSERT_EQ(1, return_opers.Length);
-            EXPECT_EQ(scalar2, return_opers[0]);  // not remapped
-            c_api.TF_DeleteImportGraphDefResults(results);
+            // Import it again, with an input mapping, return outputs, and a return
+            // operation, into the same graph.
+            Operation feed2;
+            using (SafeImportGraphDefResultsHandle results = ImportGraph(s, graph, graph_def, scalar))
+            {
+                Operation scalar2 = graph.OperationByName("imported2/scalar");
+                feed2 = graph.OperationByName("imported2/feed");
+                Operation neg2 = graph.OperationByName("imported2/neg");
+
+                // Check input mapping
+                neg_input = neg.Input(0);
+                EXPECT_EQ(scalar, neg_input.oper);
+                EXPECT_EQ(0, neg_input.index);
+
+                // Check return outputs
+                var return_outputs = graph.ReturnOutputs(results);
+                ASSERT_EQ(2, return_outputs.Length);
+                EXPECT_EQ(feed2, return_outputs[0].oper);
+                EXPECT_EQ(0, return_outputs[0].index);
+                EXPECT_EQ(scalar, return_outputs[1].oper);  // remapped
+                EXPECT_EQ(0, return_outputs[1].index);
+
+                // Check return operation
+                var return_opers = graph.ReturnOperations(results);
+                ASSERT_EQ(1, return_opers.Length);
+                EXPECT_EQ(scalar2, return_opers[0]);  // not remapped
+            }
 
             // Import again, with control dependencies, into the same graph.
             using (var opts = c_api.TF_NewImportGraphDefOptions())