Copyless data transfer

kmath-torch/ctorch/include/ctorch.h

@@ -18,10 +18,15 @@ extern "C"
 
     void set_seed(int seed);
 
-    TorchTensorHandle copy_from_blob_double(double *data, int *shape, int dim, int device);
+    double *get_data_double(TorchTensorHandle tensor_handle);
-    TorchTensorHandle copy_from_blob_float(float *data, int *shape, int dim, int device);
+    float *get_data_float(TorchTensorHandle tensor_handle);
-    TorchTensorHandle copy_from_blob_long(long *data, int *shape, int dim, int device);
+    long *get_data_long(TorchTensorHandle tensor_handle);
-    TorchTensorHandle copy_from_blob_int(int *data, int *shape, int dim, int device);
+    int *get_data_int(TorchTensorHandle tensor_handle);
+
+    TorchTensorHandle from_blob_double(double *data, int *shape, int dim, int device, bool copy);
+    TorchTensorHandle from_blob_float(float *data, int *shape, int dim, int device, bool copy);
+    TorchTensorHandle from_blob_long(long *data, int *shape, int dim, int device, bool copy);
+    TorchTensorHandle from_blob_int(int *data, int *shape, int dim, int device, bool copy);
     TorchTensorHandle copy_tensor(TorchTensorHandle tensor_handle);
     TorchTensorHandle copy_to_device(TorchTensorHandle tensor_handle, int device);
 

kmath-torch/ctorch/include/utils.hh

@@ -61,9 +61,9 @@ namespace ctorch
     }
 
     template <typename Dtype>
-    inline torch::Tensor copy_from_blob(Dtype *data, std::vector<int64_t> shape, torch::Device device)
+    inline torch::Tensor from_blob(Dtype *data, std::vector<int64_t> shape, torch::Device device, bool copy)
     {
-        return torch::from_blob(data, shape, dtype<Dtype>()).to(torch::TensorOptions().layout(torch::kStrided).device(device), false, true);
+        return torch::from_blob(data, shape, dtype<Dtype>()).to(torch::TensorOptions().layout(torch::kStrided).device(device), false, copy);
     }
 
     template <typename NumType>

kmath-torch/ctorch/src/ctorch.cc

@@ -25,6 +25,23 @@ void set_seed(int seed)
   torch::manual_seed(seed);
 }
 
+double *get_data_double(TorchTensorHandle tensor_handle)
+{
+  return ctorch::cast(tensor_handle).data_ptr<double>();
+}
+float *get_data_float(TorchTensorHandle tensor_handle)
+{
+  return ctorch::cast(tensor_handle).data_ptr<float>();
+}
+long *get_data_long(TorchTensorHandle tensor_handle)
+{
+  return ctorch::cast(tensor_handle).data_ptr<long>();
+}
+int *get_data_int(TorchTensorHandle tensor_handle)
+{
+  return ctorch::cast(tensor_handle).data_ptr<int>();
+}
+
 int get_dim(TorchTensorHandle tensor_handle)
 {
   return ctorch::cast(tensor_handle).dim();
@@ -46,21 +63,21 @@ int get_device(TorchTensorHandle tensor_handle)
   return ctorch::device_to_int(ctorch::cast(tensor_handle));
 }
 
-TorchTensorHandle copy_from_blob_double(double *data, int *shape, int dim, int device)
+TorchTensorHandle from_blob_double(double *data, int *shape, int dim, int device, bool copy)
 {
-  return new torch::Tensor(ctorch::copy_from_blob<double>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device)));
+  return new torch::Tensor(ctorch::from_blob<double>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device), copy));
 }
-TorchTensorHandle copy_from_blob_float(float *data, int *shape, int dim, int device)
+TorchTensorHandle from_blob_float(float *data, int *shape, int dim, int device, bool copy)
 {
-  return new torch::Tensor(ctorch::copy_from_blob<float>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device)));
+  return new torch::Tensor(ctorch::from_blob<float>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device), copy));
 }
-TorchTensorHandle copy_from_blob_long(long *data, int *shape, int dim, int device)
+TorchTensorHandle from_blob_long(long *data, int *shape, int dim, int device, bool copy)
 {
-  return new torch::Tensor(ctorch::copy_from_blob<long>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device)));
+  return new torch::Tensor(ctorch::from_blob<long>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device), copy));
 }
-TorchTensorHandle copy_from_blob_int(int *data, int *shape, int dim, int device)
+TorchTensorHandle from_blob_int(int *data, int *shape, int dim, int device, bool copy)
 {
-  return new torch::Tensor(ctorch::copy_from_blob<int>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device)));
+  return new torch::Tensor(ctorch::from_blob<int>(data, ctorch::to_vec_int(shape, dim), ctorch::int_to_device(device), copy));
 }
 TorchTensorHandle copy_tensor(TorchTensorHandle tensor_handle)
 {
@@ -245,7 +262,7 @@ TorchTensorHandle sum_tensor(TorchTensorHandle tensor_handle)
 }
 TorchTensorHandle transpose_tensor(TorchTensorHandle tensor_handle, int i, int j)
 {
-  return new torch::Tensor(ctorch::cast(tensor_handle).transpose(i,j));
+  return new torch::Tensor(ctorch::cast(tensor_handle).transpose(i, j));
 }
 
 bool requires_grad(TorchTensorHandle tensor_handle)

kmath-torch/src/nativeMain/kotlin/kscience.kmath.torch/TorchTensorAlgebra.kt

@@ -3,17 +3,21 @@ package kscience.kmath.torch
 import kotlinx.cinterop.*
 import kscience.kmath.ctorch.*
 
-public sealed class TorchTensorAlgebra<T, PrimitiveArrayType> constructor(
+public sealed class TorchTensorAlgebra<T, TVar: CPrimitiveVar, PrimitiveArrayType> constructor(
     internal val scope: DeferScope
 ) {
     internal abstract fun wrap(tensorHandle: COpaquePointer): TorchTensor<T>
+
     public abstract fun copyFromArray(
         array: PrimitiveArrayType,
         shape: IntArray,
         device: TorchDevice = TorchDevice.TorchCPU
     ): TorchTensor<T>
-
     public abstract fun TorchTensor<T>.copyToArray(): PrimitiveArrayType
+
+    public abstract fun fromBlob(arrayBlob: CPointer<TVar>, shape: IntArray): TorchTensor<T>
+    public abstract fun TorchTensor<T>.getData(): CPointer<TVar>
+
     public abstract fun full(value: T, shape: IntArray, device: TorchDevice): TorchTensor<T>
 
     public abstract operator fun T.times(other: TorchTensor<T>): TorchTensor<T>
@@ -56,13 +60,13 @@ public sealed class TorchTensorAlgebra<T, PrimitiveArrayType> constructor(
         wrap(autograd_tensor(this.tensorHandle, variable.tensorHandle)!!)
 }
 
-public sealed class TorchTensorFieldAlgebra<T, PrimitiveArrayType>(scope: DeferScope) :
+public sealed class TorchTensorFieldAlgebra<T, TVar: CPrimitiveVar, PrimitiveArrayType>(scope: DeferScope) :
-    TorchTensorAlgebra<T, PrimitiveArrayType>(scope) {
+    TorchTensorAlgebra<T, TVar, PrimitiveArrayType>(scope) {
     public abstract fun randNormal(shape: IntArray, device: TorchDevice = TorchDevice.TorchCPU): TorchTensor<T>
     public abstract fun randUniform(shape: IntArray, device: TorchDevice = TorchDevice.TorchCPU): TorchTensor<T>
 }
 
-public class TorchTensorRealAlgebra(scope: DeferScope) : TorchTensorFieldAlgebra<Double, DoubleArray>(scope) {
+public class TorchTensorRealAlgebra(scope: DeferScope) : TorchTensorFieldAlgebra<Double, DoubleVar, DoubleArray>(scope) {
     override fun wrap(tensorHandle: COpaquePointer): TorchTensorReal =
         TorchTensorReal(scope = scope, tensorHandle = tensorHandle)
 
@@ -76,14 +80,34 @@ public class TorchTensorRealAlgebra(scope: DeferScope) : TorchTensorFieldAlgebra
     ): TorchTensorReal =
         TorchTensorReal(
             scope = scope,
-            tensorHandle = copy_from_blob_double(
+            tensorHandle = from_blob_double(
                 array.toCValues(),
                 shape.toCValues(),
                 shape.size,
-                device.toInt()
+                device.toInt(),
+                true
             )!!
         )
 
+    override fun fromBlob(arrayBlob: CPointer<DoubleVar>, shape: IntArray): TorchTensorReal =
+        TorchTensorReal(
+            scope = scope,
+            tensorHandle = from_blob_double(
+                arrayBlob,
+                shape.toCValues(),
+                shape.size,
+                TorchDevice.TorchCPU.toInt(),
+                false
+            )!!
+        )
+
+    override fun TorchTensor<Double>.getData(): CPointer<DoubleVar> {
+        require(this.device is TorchDevice.TorchCPU){
+            "This tensor is not on available on CPU"
+        }
+        return get_data_double(this.tensorHandle)!!
+    }
+
     override fun randNormal(shape: IntArray, device: TorchDevice): TorchTensorReal = TorchTensorReal(
         scope = scope,
         tensorHandle = randn_double(shape.toCValues(), shape.size, device.toInt())!!
@@ -116,5 +140,5 @@ public class TorchTensorRealAlgebra(scope: DeferScope) : TorchTensorFieldAlgebra
 
 }
 
-public fun <R> TorchTensorRealAlgebra(block: TorchTensorRealAlgebra.() -> R): R =
+public inline fun <R> TorchTensorRealAlgebra(block: TorchTensorRealAlgebra.() -> R): R =
     memScoped { TorchTensorRealAlgebra(this).block() }

kmath-torch/src/nativeTest/kotlin/kscience/kmath/torch/TestTorchTensor.kt

@@ -1,5 +1,6 @@
 package kscience.kmath.torch
 
+import kotlinx.cinterop.*
 import kotlin.test.*
 
 internal fun testingCopyFromArray(device: TorchDevice = TorchDevice.TorchCPU): Unit {
@@ -20,6 +21,22 @@ class TestTorchTensor {
     @Test
     fun testCopyFromArray() = testingCopyFromArray()
 
+    @Test
+    fun testCopyLessDataTransferOnCPU() = memScoped {
+        val data = allocArray<DoubleVar>(1)
+        data[0] = 1.0
+        TorchTensorRealAlgebra {
+            val tensor = fromBlob(data, intArrayOf(1))
+            assertEquals(tensor[intArrayOf(0)], 1.0)
+            data[0] = 2.0
+            assertEquals(tensor[intArrayOf(0)], 2.0)
+            val tensorData = tensor.getData()
+            tensorData[0] = 3.0
+            println(assertEquals(tensor[intArrayOf(0)], 3.0))
+        }
+        assertEquals(data[0], 3.0)
+    }
+
     @Test
     fun testRequiresGrad() = TorchTensorRealAlgebra {
         val tensor = randNormal(intArrayOf(3))