Implement SafeContextHandle as a wrapper for TFE_Context

src/TensorFlowNET.Core/Device/c_api.device.cs

@@ -16,6 +16,7 @@
 
 using System;
 using System.Runtime.InteropServices;
+using Tensorflow.Eager;
 
 namespace Tensorflow
 {
@@ -64,7 +65,7 @@ namespace Tensorflow
         /// <param name="status">TF_Status*</param>
         /// <returns>TFE_TensorHandle*</returns>
         [DllImport(TensorFlowLibName)]
-        public static extern IntPtr TFE_TensorHandleCopyToDevice(IntPtr h, IntPtr ctx, string device_name, SafeStatusHandle status);
+        public static extern IntPtr TFE_TensorHandleCopyToDevice(IntPtr h, SafeContextHandle ctx, string device_name, SafeStatusHandle status);
 
         /// <summary>
         /// Retrieves the full name of the device (e.g. /job:worker/replica:0/...)

src/TensorFlowNET.Core/Eager/Context.cs

@@ -2,7 +2,7 @@
 
 namespace Tensorflow.Eager
 {
-    public class Context : DisposableObject
+    public sealed class Context : IDisposable
     {
         public const int GRAPH_MODE = 0;
         public const int EAGER_MODE = 1;
@@ -12,9 +12,11 @@ namespace Tensorflow.Eager
         public string scope_name = "";
         bool _initialized = false;
 
+        public SafeContextHandle Handle { get; }
+
         public Context(ContextOptions opts, Status status)
         {
-            _handle = c_api.TFE_NewContext(opts, status.Handle);
+            Handle = c_api.TFE_NewContext(opts, status.Handle);
             status.Check(true);
         }
 
@@ -29,16 +31,10 @@ namespace Tensorflow.Eager
         }
 
         public void start_step()
-            => c_api.TFE_ContextStartStep(_handle);
+            => c_api.TFE_ContextStartStep(Handle);
 
         public void end_step()
-            => c_api.TFE_ContextEndStep(_handle);
-
-        /// <summary>
-        ///     Dispose any unmanaged resources related to given <paramref name="handle"/>.
-        /// </summary>
-        protected sealed override void DisposeUnmanagedResources(IntPtr handle) 
-            => c_api.TFE_DeleteContext(_handle);
+            => c_api.TFE_ContextEndStep(Handle);
 
         public bool executing_eagerly() 
             => default_execution_mode == EAGER_MODE;
@@ -48,10 +44,7 @@ namespace Tensorflow.Eager
                 name : 
                 "cd2c89b7-88b7-44c8-ad83-06c2a9158347";
 
-        public static implicit operator IntPtr(Context ctx) 
-            => ctx._handle;
-
-        public static implicit operator TFE_Context(Context ctx)
-            => new TFE_Context(ctx._handle);
+        public void Dispose()
+            => Handle.Dispose();
     }
 }

src/TensorFlowNET.Core/Eager/EagerOperation.cs

@@ -53,7 +53,7 @@ namespace Tensorflow.Eager
         {
             object value = null;
             byte isList = 0;
-            var attrType = c_api.TFE_OpNameGetAttrType(tf.context, Name, attr_name, ref isList, tf.status.Handle);
+            var attrType = c_api.TFE_OpNameGetAttrType(tf.context.Handle, Name, attr_name, ref isList, tf.status.Handle);
             switch (attrType)
             {
                 case TF_AttrType.TF_ATTR_BOOL:

src/TensorFlowNET.Core/Eager/SafeContextHandle.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.Eager
+{
+    public sealed class SafeContextHandle : SafeTensorflowHandle
+    {
+        public SafeContextHandle()
+        {
+        }
+
+        public SafeContextHandle(IntPtr handle)
+            : base(handle)
+        {
+        }
+
+        protected override bool ReleaseHandle()
+        {
+            c_api.TFE_DeleteContext(handle);
+            SetHandle(IntPtr.Zero);
+            return true;
+        }
+    }
+}

src/TensorFlowNET.Core/Eager/TFE_Context.cs

@@ -1,23 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
-
-namespace Tensorflow.Eager
-{
-    public struct TFE_Context
-    {
-        IntPtr _handle;
-
-        public TFE_Context(IntPtr handle)
-            => _handle = handle;
-
-        public static implicit operator TFE_Context(IntPtr handle)
-            => new TFE_Context(handle);
-
-        public static implicit operator IntPtr(TFE_Context tensor)
-            => tensor._handle;
-
-        public override string ToString()
-            => $"TFE_Context {_handle}";
-    }
-}

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

@@ -73,7 +73,7 @@ namespace Tensorflow
         public static extern TF_AttrType TFE_OpGetAttrType(IntPtr op, string attr_name, ref byte is_list, SafeStatusHandle status);
 
         [DllImport(TensorFlowLibName)]
-        public static extern TF_AttrType TFE_OpNameGetAttrType(IntPtr ct, string op_or_function_name, string attr_name, ref byte is_list, SafeStatusHandle status);
+        public static extern TF_AttrType TFE_OpNameGetAttrType(SafeContextHandle ctx, string op_or_function_name, string attr_name, ref byte is_list, SafeStatusHandle status);
 
         /// <summary>
         /// Returns the length (number of tensors) of the input argument `input_name`
@@ -114,13 +114,13 @@ namespace Tensorflow
         /// <param name="status">TF_Status*</param>
         /// <returns>TFE_Context*</returns>
         [DllImport(TensorFlowLibName)]
-        public static extern TFE_Context TFE_NewContext(IntPtr opts, SafeStatusHandle status);
+        public static extern SafeContextHandle TFE_NewContext(IntPtr opts, SafeStatusHandle status);
 
         [DllImport(TensorFlowLibName)]
-        public static extern TFE_Context TFE_ContextStartStep(IntPtr ctx);
+        public static extern void TFE_ContextStartStep(SafeContextHandle ctx);
 
         [DllImport(TensorFlowLibName)]
-        public static extern TFE_Context TFE_ContextEndStep(IntPtr ctx);
+        public static extern void TFE_ContextEndStep(SafeContextHandle ctx);
 
         /// <summary>
         /// 
@@ -148,7 +148,7 @@ namespace Tensorflow
         /// <param name="status">TF_Status*</param>
         /// <returns></returns>
         [DllImport(TensorFlowLibName)]
-        public static extern TFE_Op TFE_NewOp(IntPtr ctx, string op_or_function_name, SafeStatusHandle status);
+        public static extern TFE_Op TFE_NewOp(SafeContextHandle ctx, string op_or_function_name, SafeStatusHandle status);
 
         /// <summary>
         /// Resets `op_to_reset` with `op_or_function_name` and `raw_device_name`. This
@@ -317,7 +317,7 @@ namespace Tensorflow
         /// <param name="status">TF_Status*</param>
         /// <returns></returns>
         [DllImport(TensorFlowLibName)]
-        public static extern IntPtr TFE_ContextListDevices(IntPtr ctx, SafeStatusHandle status);
+        public static extern IntPtr TFE_ContextListDevices(SafeContextHandle ctx, SafeStatusHandle status);
 
         /// <summary>
         /// 
@@ -379,7 +379,7 @@ namespace Tensorflow
         /// <param name="ctx"></param>
         /// <param name="executor"></param>
         [DllImport(TensorFlowLibName)]
-        public static extern void TFE_ContextSetExecutorForThread(IntPtr ctx, TFE_Executor executor);
+        public static extern void TFE_ContextSetExecutorForThread(SafeContextHandle ctx, TFE_Executor executor);
 
         /// <summary>
         /// Returns the Executor for current thread.
@@ -387,7 +387,7 @@ namespace Tensorflow
         /// <param name="ctx"></param>
         /// <returns>TFE_Executor*</returns>
         [DllImport(TensorFlowLibName)]
-        public static extern TFE_Executor TFE_ContextGetExecutorForThread(IntPtr ctx);
+        public static extern TFE_Executor TFE_ContextGetExecutorForThread(SafeContextHandle ctx);
 
         /// <summary>
         /// 
@@ -402,7 +402,7 @@ namespace Tensorflow
         /// <param name="status"></param>
         /// <returns>EagerTensorHandle</returns>
         [DllImport(TensorFlowLibName)]
-        public static extern SafeStatusHandle TFE_FastPathExecute(IntPtr ctx, 
+        public static extern SafeStatusHandle TFE_FastPathExecute(SafeContextHandle ctx, 
             string device_name, 
             string op_name,
             string name,
@@ -416,7 +416,7 @@ namespace Tensorflow
         public delegate void TFE_FastPathExecute_SetOpAttrs(IntPtr op);
 
         [DllImport(TensorFlowLibName)]
-        public static extern SafeStatusHandle TFE_QuickExecute(IntPtr ctx,
+        public static extern SafeStatusHandle TFE_QuickExecute(SafeContextHandle ctx,
             string device_name,
             string op_name,
             IntPtr[] inputs, 

test/TensorFlowNET.UnitTest/NativeAPI/CApiTest.cs

@@ -1,6 +1,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using System;
 using Tensorflow;
+using Tensorflow.Eager;
 using Buffer = System.Buffer;
 
 namespace TensorFlowNET.UnitTest
@@ -92,7 +93,7 @@ namespace TensorFlowNET.UnitTest
         protected void TFE_OpSetAttrString(IntPtr op, string attr_name, string value, uint length)
             => c_api.TFE_OpSetAttrString(op, attr_name, value, length);
 
-        protected IntPtr TFE_NewOp(IntPtr ctx, string op_or_function_name, SafeStatusHandle status)
+        protected IntPtr TFE_NewOp(SafeContextHandle ctx, string op_or_function_name, SafeStatusHandle status)
             => c_api.TFE_NewOp(ctx, op_or_function_name, status);
 
         protected IntPtr TFE_NewTensorHandle(IntPtr t, SafeStatusHandle status)
@@ -104,10 +105,7 @@ namespace TensorFlowNET.UnitTest
         protected IntPtr TFE_NewContextOptions()
             => c_api.TFE_NewContextOptions();
 
-        protected void TFE_DeleteContext(IntPtr t)
-            => c_api.TFE_DeleteContext(t);
-
-        protected IntPtr TFE_NewContext(IntPtr opts, SafeStatusHandle status)
+        protected SafeContextHandle TFE_NewContext(IntPtr opts, SafeStatusHandle status)
             => c_api.TFE_NewContext(opts, status);
 
         protected void TFE_DeleteContextOptions(IntPtr opts)
@@ -131,7 +129,7 @@ namespace TensorFlowNET.UnitTest
         protected void TFE_DeleteExecutor(IntPtr executor)
             => c_api.TFE_DeleteExecutor(executor);
 
-        protected IntPtr TFE_ContextGetExecutorForThread(IntPtr ctx)
+        protected IntPtr TFE_ContextGetExecutorForThread(SafeContextHandle ctx)
             => c_api.TFE_ContextGetExecutorForThread(ctx);
 
         protected void TFE_ExecutorWaitForAllPendingNodes(IntPtr executor, SafeStatusHandle status)
@@ -146,7 +144,7 @@ namespace TensorFlowNET.UnitTest
         protected string TFE_TensorHandleBackingDeviceName(IntPtr h, SafeStatusHandle status)
             => c_api.StringPiece(c_api.TFE_TensorHandleBackingDeviceName(h, status));
 
-        protected IntPtr TFE_ContextListDevices(IntPtr ctx, SafeStatusHandle status)
+        protected IntPtr TFE_ContextListDevices(SafeContextHandle ctx, SafeStatusHandle status)
             => c_api.TFE_ContextListDevices(ctx, status);
 
         protected int TF_DeviceListCount(IntPtr list)
@@ -161,7 +159,7 @@ namespace TensorFlowNET.UnitTest
         protected void TF_DeleteDeviceList(IntPtr list)
             => c_api.TF_DeleteDeviceList(list);
 
-        protected IntPtr TFE_TensorHandleCopyToDevice(IntPtr h, IntPtr ctx, string device_name, SafeStatusHandle status)
+        protected IntPtr TFE_TensorHandleCopyToDevice(IntPtr h, SafeContextHandle ctx, string device_name, SafeStatusHandle status)
             => c_api.TFE_TensorHandleCopyToDevice(h, ctx, device_name, status);
 
         protected void TFE_OpSetDevice(IntPtr op, string device_name, SafeStatusHandle status)

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

@@ -1,7 +1,6 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using System;
 using Tensorflow;
-using Tensorflow.Eager;
 
 namespace TensorFlowNET.UnitTest.NativeAPI
 {
@@ -15,14 +14,16 @@ namespace TensorFlowNET.UnitTest.NativeAPI
         {
             using var status = c_api.TF_NewStatus();
             var opts = c_api.TFE_NewContextOptions();
-            var ctx = c_api.TFE_NewContext(opts, status);
 
-            c_api.TFE_DeleteContextOptions(opts);
+            IntPtr devices;
+            using (var ctx = c_api.TFE_NewContext(opts, status))
+            {
+                c_api.TFE_DeleteContextOptions(opts);
 
-            var devices = c_api.TFE_ContextListDevices(ctx, status);
-            EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+                devices = c_api.TFE_ContextListDevices(ctx, status);
+                EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+            }
 
-            c_api.TFE_DeleteContext(ctx);
             EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
 
             int num_devices = c_api.TF_DeviceListCount(devices);

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

@@ -21,24 +21,28 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             using var status = TF_NewStatus();
             var opts = TFE_NewContextOptions();
             c_api.TFE_ContextOptionsSetAsync(opts, Convert.ToByte(async));
-            var ctx = TFE_NewContext(opts, status);
-            CHECK_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
-            TFE_DeleteContextOptions(opts);
 
-            var m = TestMatrixTensorHandle();
-            var matmul = MatMulOp(ctx, m, m);
-            var retvals = new IntPtr[] { IntPtr.Zero, IntPtr.Zero };
-            int num_retvals = 2;
-            c_api.TFE_Execute(matmul, retvals, ref num_retvals, status);
-            EXPECT_EQ(1, num_retvals);
-            EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
-            TFE_DeleteOp(matmul);
-            TFE_DeleteTensorHandle(m);
+            IntPtr t;
+            using (var ctx = TFE_NewContext(opts, status))
+            {
+                CHECK_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+                TFE_DeleteContextOptions(opts);
+
+                var m = TestMatrixTensorHandle();
+                var matmul = MatMulOp(ctx, m, m);
+                var retvals = new IntPtr[] { IntPtr.Zero, IntPtr.Zero };
+                int num_retvals = 2;
+                c_api.TFE_Execute(matmul, retvals, ref num_retvals, status);
+                EXPECT_EQ(1, num_retvals);
+                EXPECT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+                TFE_DeleteOp(matmul);
+                TFE_DeleteTensorHandle(m);
+
+                t = TFE_TensorHandleResolve(retvals[0], status);
+                ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
+                TFE_DeleteTensorHandle(retvals[0]);
+            }
 
-            var t = TFE_TensorHandleResolve(retvals[0], status);
-            ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
-            TFE_DeleteTensorHandle(retvals[0]);
-            TFE_DeleteContext(ctx);
             ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
             var product = new float[4];
             EXPECT_EQ(product.Length * sizeof(float), (int)TF_TensorByteSize(t));

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

@@ -16,7 +16,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
         {
             using var status = TF_NewStatus();
             var opts = TFE_NewContextOptions();
-            var ctx = TFE_NewContext(opts, status);
+            using var ctx = TFE_NewContext(opts, status);
             CHECK_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
             TFE_DeleteContextOptions(opts);
 
@@ -57,7 +57,6 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             TFE_DeleteTensorHandle(input2);
             TFE_DeleteTensorHandle(retvals[0]);
             TFE_DeleteTensorHandle(retvals[1]);
-            TFE_DeleteContext(ctx);
         }
     }
 }

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

@@ -18,7 +18,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
         {
             using var status = TF_NewStatus();
             var opts = TFE_NewContextOptions();
-            var ctx = TFE_NewContext(opts, status);
+            using var ctx = TFE_NewContext(opts, status);
             CHECK_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
             TFE_DeleteContextOptions(opts);
 
@@ -50,7 +50,6 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             TFE_DeleteTensorHandle(t1);
             TFE_DeleteTensorHandle(t2);
             TFE_DeleteTensorHandle(retvals[0]);
-            TFE_DeleteContext(ctx);
         }
     }
 }

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

@@ -16,7 +16,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
         {
             var status = c_api.TF_NewStatus();
             var opts = TFE_NewContextOptions();
-            var ctx = TFE_NewContext(opts, status);
+            using var ctx = TFE_NewContext(opts, status);
             TFE_DeleteContextOptions(opts);
             ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
 
@@ -65,7 +65,6 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             TFE_ExecutorWaitForAllPendingNodes(executor, status);
             ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
             TFE_DeleteExecutor(executor);
-            TFE_DeleteContext(ctx);
         }
     }
 }

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

@@ -15,7 +15,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
         {
             using var status = c_api.TF_NewStatus();
             var opts = TFE_NewContextOptions();
-            var ctx = TFE_NewContext(opts, status);
+            using var ctx = TFE_NewContext(opts, status);
             ASSERT_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
             TFE_DeleteContextOptions(opts);
 
@@ -47,7 +47,6 @@ namespace TensorFlowNET.UnitTest.NativeAPI
 
             TFE_DeleteTensorHandle(var_handle);
             TFE_DeleteTensorHandle(value_handle[0]);
-            TFE_DeleteContext(ctx);
             CHECK_EQ(TF_OK, TF_GetCode(status), TF_Message(status));
         }
     }

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

@@ -1,6 +1,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using System;
 using Tensorflow;
+using Tensorflow.Eager;
 using static Tensorflow.Binding;
 
 namespace TensorFlowNET.UnitTest.NativeAPI
@@ -25,7 +26,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             return th;
         }
 
-        IntPtr MatMulOp(IntPtr ctx, IntPtr a, IntPtr b)
+        IntPtr MatMulOp(SafeContextHandle ctx, IntPtr a, IntPtr b)
         {
             using var status = TF_NewStatus();
 
@@ -40,7 +41,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             return op;
         }
 
-        bool GetDeviceName(IntPtr ctx, ref string device_name, string device_type)
+        bool GetDeviceName(SafeContextHandle ctx, ref string device_name, string device_type)
         {
             var status = TF_NewStatus();
             var devices = TFE_ContextListDevices(ctx, status);
@@ -65,7 +66,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             return false;
         }
 
-        IntPtr ShapeOp(IntPtr ctx, IntPtr a)
+        IntPtr ShapeOp(SafeContextHandle ctx, IntPtr a)
         {
             using var status = TF_NewStatus();
 
@@ -78,7 +79,7 @@ namespace TensorFlowNET.UnitTest.NativeAPI
             return op;
         }
 
-        unsafe IntPtr CreateVariable(IntPtr ctx, float value, SafeStatusHandle status)
+        unsafe IntPtr CreateVariable(SafeContextHandle ctx, float value, SafeStatusHandle status)
         {
             var op = TFE_NewOp(ctx, "VarHandleOp", status);
             if (TF_GetCode(status) != TF_OK) return IntPtr.Zero;