Simplify code using SafeTensorHandleHandle

src/TensorFlowNET.Core/Eager/c_api.eager.cs

@@ -91,6 +91,18 @@ namespace Tensorflow
         [DllImport(TensorFlowLibName)]
         public static extern void TFE_DeleteContext(IntPtr ctx);
 
+        /// <summary>
+        /// Execute the operation defined by <paramref name="op"/> and return handles to computed
+        /// tensors in <paramref name="retvals"/>.
+        /// </summary>
+        /// <remarks>
+        /// Upon successful return, the first <paramref name="num_retvals"/> slots in <paramref name="retvals"/> will
+        /// contain handle instances which the caller is responsible for disposing once they are no longer in use.
+        /// </remarks>
+        /// <param name="op"></param>
+        /// <param name="retvals"></param>
+        /// <param name="num_retvals"></param>
+        /// <param name="status"></param>
         public static void TFE_Execute(SafeOpHandle op, SafeTensorHandleHandle[] retvals, out int num_retvals, SafeStatusHandle status)
         {
             unsafe
@@ -100,6 +112,9 @@ namespace Tensorflow
                 TFE_Execute(op, rawReturns, ref num_retvals, status);
                 for (var i = 0; i < num_retvals; i++)
                 {
+                    // A handle is created for every return, even if rawReturns[i] is null. The resulting handle will be
+                    // non-null but invalid, which is the same behavior P/Invoke gives for non-array SafeHandle return
+                    // values.
                     retvals[i] = new SafeTensorHandleHandle(rawReturns[i]);
                 }
             }

test/TensorFlowNET.UnitTest/NativeAPI/Eager/CApi.Eager.Execute_MatMul_CPU.cs

@@ -34,23 +34,23 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 CHECK_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
 
                 var retvals = new SafeTensorHandleHandle[2];
-                try
+                using (var m = TestMatrixTensorHandle())
+                using (var matmul = MatMulOp(ctx, m, m))
                 {
-                    using (var m = TestMatrixTensorHandle())
-                    using (var matmul = MatMulOp(ctx, m, m))
-                    {
-                        int num_retvals;
-                        c_api.TFE_Execute(matmul, retvals, out num_retvals, status);
-                        EXPECT_EQ(1, num_retvals);
-                        EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
-                    }
+                    int num_retvals;
+                    c_api.TFE_Execute(matmul, retvals, out num_retvals, status);
+                    EXPECT_EQ(1, num_retvals);
+                    EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+                }
 
+                try
+                {
                     t = TFE_TensorHandleResolve(retvals[0], status);
                     ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
                 }
                 finally
                 {
-                    retvals[0]?.Dispose();
+                    retvals[0].Dispose();
                 }
             }
 

test/TensorFlowNET.UnitTest/NativeAPI/Eager/CApi.Eager.OpGetInputAndOutputLengths.cs

@@ -51,6 +51,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 int num_retvals;
                 TFE_Execute(identityOp, retvals, out num_retvals, status);
                 EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+                EXPECT_EQ(2, num_retvals);
 
                 try
                 {
@@ -62,8 +63,8 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 }
                 finally
                 {
-                    retvals[0]?.Dispose();
-                    retvals[1]?.Dispose();
+                    retvals[0].Dispose();
+                    retvals[1].Dispose();
                 }
             }
         }

test/TensorFlowNET.UnitTest/NativeAPI/Eager/CApi.Eager.OpInferMixedTypeInputListAttrs.cs

@@ -46,8 +46,9 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 int num_retvals;
                 TFE_Execute(assertOp, retvals, out num_retvals, status);
                 EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+                EXPECT_EQ(1, num_retvals);
 
-                retvals[0]?.Dispose();
+                retvals[0].Dispose();
             }
         }
     }

test/TensorFlowNET.UnitTest/NativeAPI/Eager/CApi.Eager.TensorHandleDevices.cs

@@ -49,6 +49,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                         int num_retvals;
                         c_api.TFE_Execute(shape_op, retvals, out num_retvals, status);
                         ASSERT_TRUE(TF_GetCode(status) == TF_OK, TF_Message(status));
+                        ASSERT_EQ(1, num_retvals);
 
                         try
                         {
@@ -64,7 +65,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                         }
                         finally
                         {
-                            retvals[0]?.Dispose();
+                            retvals[0].Dispose();
                         }
                     }
                 }

test/TensorFlowNET.UnitTest/NativeAPI/Eager/CApi.Eager.Variables.cs

@@ -38,6 +38,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                     TFE_OpAddInput(op, var_handle, status);
                     ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
                     TFE_Execute(op, value_handle, out num_retvals, status);
+                    ASSERT_EQ(1, num_retvals);
                 }
 
                 try
@@ -57,7 +58,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 }
                 finally
                 {
-                    value_handle[0]?.Dispose();
+                    value_handle[0].Dispose();
                 }
             }
 

test/TensorFlowNET.UnitTest/NativeAPI/Eager/CApi.Eager.cs

@@ -90,11 +90,10 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 TFE_OpSetAttrString(op, "shared_name", "", 0);
                 if (TF_GetCode(status) != TF_OK) return new SafeTensorHandleHandle(IntPtr.Zero);
                 TFE_Execute(op, var_handle, out num_retvals, status);
+                if (TF_GetCode(status) != TF_OK) return new SafeTensorHandleHandle(IntPtr.Zero);
+                CHECK_EQ(1, num_retvals);
             }
 
-            if (TF_GetCode(status) != TF_OK) return new SafeTensorHandleHandle(IntPtr.Zero);
-            CHECK_EQ(1, num_retvals);
-
             // Assign 'value' to it.
             using (var op = TFE_NewOp(ctx, "AssignVariableOp", status))
             {
@@ -112,13 +111,11 @@ namespace TensorFlowNET.UnitTest.NativeAPI
                 TFE_OpAddInput(op, value_handle, status);
                 if (TF_GetCode(status) != TF_OK) return new SafeTensorHandleHandle(IntPtr.Zero);
 
-                num_retvals = 0;
                 c_api.TFE_Execute(op, null, out num_retvals, status);
+                if (TF_GetCode(status) != TF_OK) return new SafeTensorHandleHandle(IntPtr.Zero);
+                CHECK_EQ(0, num_retvals);
             }
 
-            if (TF_GetCode(status) != TF_OK) return new SafeTensorHandleHandle(IntPtr.Zero);
-            CHECK_EQ(0, num_retvals);
-
             return var_handle[0];
         }