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lostmsulostmsu
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implements buffer interface for .NET arrays of primitive types (#1511)
fixes losttech/Gradient#27
1 parent 1e32d8c commit ee0ab7f

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‎.github/workflows/main.yml

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@@ -41,6 +41,7 @@ jobs:
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- name: Install dependencies
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run: |
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pip install --upgrade -r requirements.txt
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pip install numpy # for tests
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- name: Build and Install
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run: |

‎CHANGELOG.md

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@@ -15,8 +15,10 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
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- Ability to implement delegates with `ref` and `out` parameters in Python, by returning the modified parameter values in a tuple. ([#1355][i1355])
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- `PyType` - a wrapper for Python type objects, that also permits creating new heap types from `TypeSpec`
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- Improved exception handling:
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- exceptions can now be converted with codecs
19-
- `InnerException` and `__cause__` are propagated properly
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- exceptions can now be converted with codecs
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- `InnerException` and `__cause__` are propagated properly
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- .NET arrays implement Python buffer protocol
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2022

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### Changed
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- Drop support for Python 2, 3.4, and 3.5

‎src/embed_tests/NumPyTests.cs

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@@ -0,0 +1,94 @@
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using System;
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using System.Collections.Generic;
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using NUnit.Framework;
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using Python.Runtime;
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using Python.Runtime.Codecs;
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namespace Python.EmbeddingTest
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{
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public class NumPyTests
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{
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[OneTimeSetUp]
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public void SetUp()
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{
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PythonEngine.Initialize();
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TupleCodec<ValueTuple>.Register();
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}
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[OneTimeTearDown]
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public void Dispose()
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{
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PythonEngine.Shutdown();
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}
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[Test]
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public void TestReadme()
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{
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dynamic np;
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try
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{
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np = Py.Import("numpy");
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}
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catch (PythonException)
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{
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Assert.Inconclusive("Numpy or dependency not installed");
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return;
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}
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Assert.AreEqual("1.0", np.cos(np.pi * 2).ToString());
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dynamic sin = np.sin;
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StringAssert.StartsWith("-0.95892", sin(5).ToString());
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double c = np.cos(5) + sin(5);
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Assert.AreEqual(-0.675262, c, 0.01);
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dynamic a = np.array(new List<float> { 1, 2, 3 });
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Assert.AreEqual("float64", a.dtype.ToString());
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dynamic b = np.array(new List<float> { 6, 5, 4 }, Py.kw("dtype", np.int32));
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Assert.AreEqual("int32", b.dtype.ToString());
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Assert.AreEqual("[ 6. 10. 12.]", (a * b).ToString().Replace(" ", " "));
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}
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[Test]
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public void MultidimensionalNumPyArray()
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{
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PyObject np;
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try {
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np = Py.Import("numpy");
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} catch (PythonException) {
62+
Assert.Inconclusive("Numpy or dependency not installed");
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return;
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}
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var array = new[,] { { 1, 2 }, { 3, 4 } };
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var ndarray = np.InvokeMethod("asarray", array.ToPython());
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Assert.AreEqual((2,2), ndarray.GetAttr("shape").As<(int,int)>());
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Assert.AreEqual(1, ndarray[(0, 0).ToPython()].InvokeMethod("__int__").As<int>());
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Assert.AreEqual(array[1, 0], ndarray[(1, 0).ToPython()].InvokeMethod("__int__").As<int>());
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}
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[Test]
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public void Int64Array()
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{
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PyObject np;
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try
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{
79+
np = Py.Import("numpy");
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}
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catch (PythonException)
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{
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Assert.Inconclusive("Numpy or dependency not installed");
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return;
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}
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var array = new long[,] { { 1, 2 }, { 3, 4 } };
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var ndarray = np.InvokeMethod("asarray", array.ToPython());
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Assert.AreEqual((2, 2), ndarray.GetAttr("shape").As<(int, int)>());
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Assert.AreEqual(1, ndarray[(0, 0).ToPython()].InvokeMethod("__int__").As<long>());
91+
Assert.AreEqual(array[1, 0], ndarray[(1, 0).ToPython()].InvokeMethod("__int__").As<long>());
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}
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}
94+
}

‎src/embed_tests/TestExample.cs

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This file was deleted.

‎src/embed_tests/TestPyBuffer.cs

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@@ -1,6 +1,8 @@
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using System;
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using System.Text;
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using NUnit.Framework;
34
using Python.Runtime;
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using Python.Runtime.Codecs;
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57
namespace Python.EmbeddingTest {
68
class TestPyBuffer
@@ -9,6 +11,7 @@ class TestPyBuffer
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public void SetUp()
1012
{
1113
PythonEngine.Initialize();
14+
TupleCodec<ValueTuple>.Register();
1215
}
1316

1417
[OneTimeTearDown]
@@ -64,5 +67,15 @@ public void TestBufferRead()
6467
}
6568
}
6669
}
70+
71+
[Test]
72+
public void ArrayHasBuffer()
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{
74+
var array = new[,] {{1, 2}, {3,4}};
75+
var memoryView = PythonEngine.Eval("memoryview");
76+
var mem = memoryView.Invoke(array.ToPython());
77+
Assert.AreEqual(1, mem[(0, 0).ToPython()].As<int>());
78+
Assert.AreEqual(array[1,0], mem[(1, 0).ToPython()].As<int>());
79+
}
6780
}
6881
}

‎src/runtime/arrayobject.cs

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@@ -1,5 +1,7 @@
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using System;
22
using System.Collections;
3+
using System.Collections.Generic;
4+
using System.Runtime.InteropServices;
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46
namespace Python.Runtime
57
{
@@ -366,5 +368,166 @@ public static int sq_contains(IntPtr ob, IntPtr v)
366368

367369
return 0;
368370
}
371+
372+
#region Buffer protocol
373+
static int GetBuffer(BorrowedReference obj, out Py_buffer buffer, PyBUF flags)
374+
{
375+
buffer = default;
376+
377+
if (flags == PyBUF.SIMPLE)
378+
{
379+
Exceptions.SetError(Exceptions.BufferError, "SIMPLE not implemented");
380+
return -1;
381+
}
382+
if ((flags & PyBUF.F_CONTIGUOUS) == PyBUF.F_CONTIGUOUS)
383+
{
384+
Exceptions.SetError(Exceptions.BufferError, "only C-contiguous supported");
385+
return -1;
386+
}
387+
var self = (Array)((CLRObject)GetManagedObject(obj)).inst;
388+
Type itemType = self.GetType().GetElementType();
389+
390+
bool formatRequested = (flags & PyBUF.FORMATS) != 0;
391+
string format = GetFormat(itemType);
392+
if (formatRequested && format is null)
393+
{
394+
Exceptions.SetError(Exceptions.BufferError, "unsupported element type: " + itemType.Name);
395+
return -1;
396+
}
397+
GCHandle gcHandle;
398+
try
399+
{
400+
gcHandle = GCHandle.Alloc(self, GCHandleType.Pinned);
401+
} catch (ArgumentException ex)
402+
{
403+
Exceptions.SetError(Exceptions.BufferError, ex.Message);
404+
return -1;
405+
}
406+
407+
int itemSize = Marshal.SizeOf(itemType);
408+
IntPtr[] shape = GetShape(self);
409+
IntPtr[] strides = GetStrides(shape, itemSize);
410+
buffer = new Py_buffer
411+
{
412+
buf = gcHandle.AddrOfPinnedObject(),
413+
obj = Runtime.SelfIncRef(obj.DangerousGetAddress()),
414+
len = (IntPtr)(self.LongLength*itemSize),
415+
itemsize = (IntPtr)itemSize,
416+
_readonly = false,
417+
ndim = self.Rank,
418+
format = format,
419+
shape = ToUnmanaged(shape),
420+
strides = (flags & PyBUF.STRIDES) == PyBUF.STRIDES ? ToUnmanaged(strides) : IntPtr.Zero,
421+
suboffsets = IntPtr.Zero,
422+
_internal = (IntPtr)gcHandle,
423+
};
424+
425+
return 0;
426+
}
427+
static void ReleaseBuffer(BorrowedReference obj, ref Py_buffer buffer)
428+
{
429+
if (buffer._internal == IntPtr.Zero) return;
430+
431+
UnmanagedFree(ref buffer.shape);
432+
UnmanagedFree(ref buffer.strides);
433+
UnmanagedFree(ref buffer.suboffsets);
434+
435+
var gcHandle = (GCHandle)buffer._internal;
436+
gcHandle.Free();
437+
buffer._internal = IntPtr.Zero;
438+
}
439+
440+
static IntPtr[] GetStrides(IntPtr[] shape, long itemSize)
441+
{
442+
var result = new IntPtr[shape.Length];
443+
result[shape.Length - 1] = new IntPtr(itemSize);
444+
for (int dim = shape.Length - 2; dim >= 0; dim--)
445+
{
446+
itemSize *= shape[dim + 1].ToInt64();
447+
result[dim] = new IntPtr(itemSize);
448+
}
449+
return result;
450+
}
451+
static IntPtr[] GetShape(Array array)
452+
{
453+
var result = new IntPtr[array.Rank];
454+
for (int i = 0; i < result.Length; i++)
455+
result[i] = (IntPtr)array.GetLongLength(i);
456+
return result;
457+
}
458+
459+
static void UnmanagedFree(ref IntPtr address)
460+
{
461+
if (address == IntPtr.Zero) return;
462+
463+
Marshal.FreeHGlobal(address);
464+
address = IntPtr.Zero;
465+
}
466+
static unsafe IntPtr ToUnmanaged<T>(T[] array) where T : unmanaged
467+
{
468+
IntPtr result = Marshal.AllocHGlobal(checked(Marshal.SizeOf(typeof(T)) * array.Length));
469+
fixed (T* ptr = array)
470+
{
471+
var @out = (T*)result;
472+
for (int i = 0; i < array.Length; i++)
473+
@out[i] = ptr[i];
474+
}
475+
return result;
476+
}
477+
478+
static readonly Dictionary<Type, string> ItemFormats = new Dictionary<Type, string>
479+
{
480+
[typeof(byte)] = "B",
481+
[typeof(sbyte)] = "b",
482+
483+
[typeof(bool)] = "?",
484+
485+
[typeof(short)] = "h",
486+
[typeof(ushort)] = "H",
487+
// see https://github.com/pybind/pybind11/issues/1908#issuecomment-658358767
488+
[typeof(int)] = "i",
489+
[typeof(uint)] = "I",
490+
[typeof(long)] = "q",
491+
[typeof(ulong)] = "Q",
492+
493+
[typeof(IntPtr)] = "n",
494+
[typeof(UIntPtr)] = "N",
495+
496+
// TODO: half = "e"
497+
[typeof(float)] = "f",
498+
[typeof(double)] = "d",
499+
};
500+
501+
static string GetFormat(Type elementType)
502+
=> ItemFormats.TryGetValue(elementType, out string result) ? result : null;
503+
504+
static readonly GetBufferProc getBufferProc = GetBuffer;
505+
static readonly ReleaseBufferProc releaseBufferProc = ReleaseBuffer;
506+
static readonly IntPtr BufferProcsAddress = AllocateBufferProcs();
507+
static IntPtr AllocateBufferProcs()
508+
{
509+
var procs = new PyBufferProcs
510+
{
511+
Get = Marshal.GetFunctionPointerForDelegate(getBufferProc),
512+
Release = Marshal.GetFunctionPointerForDelegate(releaseBufferProc),
513+
};
514+
IntPtr result = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(PyBufferProcs)));
515+
Marshal.StructureToPtr(procs, result, fDeleteOld: false);
516+
return result;
517+
}
518+
#endregion
519+
520+
/// <summary>
521+
/// <see cref="TypeManager.InitializeSlots(IntPtr, Type, SlotsHolder)"/>
522+
/// </summary>
523+
public static void InitializeSlots(IntPtr type, ISet<string> initialized, SlotsHolder slotsHolder)
524+
{
525+
if (initialized.Add(nameof(TypeOffset.tp_as_buffer)))
526+
{
527+
// TODO: only for unmanaged arrays
528+
int offset = TypeOffset.GetSlotOffset(nameof(TypeOffset.tp_as_buffer));
529+
Marshal.WriteIntPtr(type, offset, BufferProcsAddress);
530+
}
531+
}
369532
}
370533
}

‎src/runtime/bufferinterface.cs

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@@ -103,4 +103,15 @@ public enum PyBUF
103103
/// </summary>
104104
FULL_RO = (INDIRECT | FORMATS),
105105
}
106+
107+
internal struct PyBufferProcs
108+
{
109+
public IntPtr Get;
110+
public IntPtr Release;
111+
}
112+
113+
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
114+
delegate int GetBufferProc(BorrowedReference obj, out Py_buffer buffer, PyBUF flags);
115+
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
116+
delegate void ReleaseBufferProc(BorrowedReference obj, ref Py_buffer buffer);
106117
}

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