Add the constructor of ndarray which reuse memory.

Author: SanftMonster

src/TensorFlowNET.Core/Numpy/NDArray.Creation.cs

@@ -8,6 +8,7 @@ namespace Tensorflow.NumPy
 {
     public partial class NDArray
     {
+        protected NDArray() { }
         public NDArray(bool value) : base(value) => NewEagerTensorHandle(); 
         public NDArray(byte value) : base(value) => NewEagerTensorHandle();
         public NDArray(short value) : base(value) => NewEagerTensorHandle();
@@ -57,6 +58,20 @@ public static NDArray Scalar<T>(T value) where T : unmanaged
                 _ => throw new NotImplementedException("")
             };
 
+        /// <summary>
+        /// Reuse the existing memory instead of copying it.
+        /// </summary>
+        /// <param name="data_ptr"></param>
+        /// <param name="shape"></param>
+        /// <param name="dtype"></param>
+        /// <param name="deallocator"></param>
+        protected void InitWithExistingMemory(IntPtr data_ptr, Shape shape, TF_DataType dtype, c_api.DeallocatorV2 deallocator)
+        {
+            _handle = c_api.TF_NewTensor(TF_DataType.TF_STRING, shape.dims, shape.ndim, data_ptr, (ulong)(shape.size * dtype.get_datatype_size()), deallocator, IntPtr.Zero);
+            tensor_util.DangerousManuallySetTensorDType(_handle, dtype);
+            NewEagerTensorHandle();
+        }
+
         void NewEagerTensorHandle()
         {
             if (_handle is not null)

src/TensorFlowNET.Core/Operations/array_ops.cs

@@ -417,7 +417,7 @@ public static Tensor ones(Shape shape, TF_DataType dtype = TF_DataType.TF_FLOAT,
                 {
                     TF_DataType.TF_DOUBLE => constant(1.0d),
                     TF_DataType.TF_FLOAT => constant(1.0f),
-                    _ => constant(1)
+                    _ => constant(1, dtype)
                 };
 
                 if (shape.ndim == 0)

src/TensorFlowNET.Core/Tensors/c_api.tensor.cs

@@ -71,7 +71,7 @@ public partial class c_api
         /// <param name="deallocator_arg"></param>
         /// <returns></returns>
         [DllImport(TensorFlowLibName)]
-        public static extern SafeTensorHandle TF_NewTensor(TF_DataType dataType, long[] dims, int num_dims, IntPtr data, ulong len, Deallocator deallocator, IntPtr deallocator_arg);
+        public static extern SafeTensorHandle TF_NewTensor(TF_DataType dataType, long[] dims, int num_dims, IntPtr data, ulong len, DeallocatorV2 deallocator, IntPtr deallocator_arg);
 
         public static unsafe SafeTensorHandle TF_NewTensor(byte[] data, Shape shape, TF_DataType dtype)
         {
@@ -147,6 +147,15 @@ public static unsafe SafeTensorHandle TF_NewTensor<T>(T value)
         [DllImport(TensorFlowLibName)]
         public static extern TF_DataType TF_TensorType(SafeTensorHandle tensor);
 
+        /// <summary>
+        /// Set a new shape for the Tensor. Note that this API only works after tf2.11.
+        /// </summary>
+        /// <param name="tensor"></param>
+        /// <param name="dims"></param>
+        /// <param name="num_dims"></param>
+        [DllImport(TensorFlowLibName)]
+        public static extern void TF_SetShape(SafeTensorHandle tensor, long[] dims, int num_dims);
+
         /// <summary>
         /// Return the size in bytes required to encode a string `len` bytes long into a
         /// TF_STRING tensor.

src/TensorFlowNET.Core/Tensors/tensor_util.cs

@@ -22,6 +22,7 @@ limitations under the License.
 using Tensorflow.Eager;
 using Tensorflow.Graphs;
 using static Tensorflow.Binding;
+using System.Diagnostics;
 
 namespace Tensorflow
 {
@@ -649,5 +650,24 @@ public static ParsedSliceArgs ParseSlices(Tensor start, Tensor stop = null, Tens
                 NewAxisMask = new_axis_mask
             };
         }
+
+        /// <summary>
+        /// Warning: this method is an extremely dangerous method. It directly changes the dtype inside the tensor 
+        /// and security is not guaranteed at all. Currently this method is only used for some conditions to reuse 
+        /// the existing memory. Any other usage should be prevented. If you are sure you want to use it when 
+        /// developing tensorflow.net, please ask @Oceanic2018 or @AsakusaRinne first.
+        /// </summary>
+        /// <param name="handle"></param>
+        /// <param name="dtype"></param>
+        internal static unsafe void DangerousManuallySetTensorDType(SafeTensorHandle handle, TF_DataType dtype)
+        {
+            long tf_tensor_address = handle.DangerousGetHandle().ToInt64();
+            long interface_address = *(long*)(tf_tensor_address);
+            long tensor_shape_address = interface_address + 8;
+            long tensor_dtype_address = tensor_shape_address + 13;
+            byte* dtype_pointer = (byte*)tensor_dtype_address;
+            *dtype_pointer = (byte)dtype;
+            Debug.Assert(c_api.TF_TensorType(handle) == dtype);
+        }
     }
 }