jorisvandenbossche commented on code in PR #41685:
URL: https://github.com/apache/arrow/pull/41685#discussion_r1618666183


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python/pyarrow/device.pxi:
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@@ -0,0 +1,162 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+# cython: profile=False
+# distutils: language = c++
+# cython: embedsignature = True
+
+
+cpdef enum DeviceAllocationType:
+    CPU = <char> CDeviceAllocationType_kCPU
+    CUDA = <char> CDeviceAllocationType_kCUDA
+    CUDA_HOST = <char> CDeviceAllocationType_kCUDA_HOST
+    OPENCL = <char> CDeviceAllocationType_kOPENCL
+    VULKAN = <char> CDeviceAllocationType_kVULKAN
+    METAL = <char> CDeviceAllocationType_kMETAL
+    VPI = <char> CDeviceAllocationType_kVPI
+    ROCM = <char> CDeviceAllocationType_kROCM
+    ROCM_HOST = <char> CDeviceAllocationType_kROCM_HOST
+    EXT_DEV = <char> CDeviceAllocationType_kEXT_DEV
+    CUDA_MANAGED = <char> CDeviceAllocationType_kCUDA_MANAGED
+    ONEAPI = <char> CDeviceAllocationType_kONEAPI
+    WEBGPU = <char> CDeviceAllocationType_kWEBGPU
+    HEXAGON = <char> CDeviceAllocationType_kHEXAGON
+
+
+cdef object _wrap_device_allocation_type(CDeviceAllocationType device_type):
+    return DeviceAllocationType(<char> device_type)
+
+
+cdef class Device(_Weakrefable):
+    """
+    Abstract interface for hardware devices
+
+    This object represents a device with access to some memory spaces.
+    When handling a Buffer or raw memory address, it allows deciding in which
+    context the raw memory address should be interpreted
+    (e.g. CPU-accessible memory, or embedded memory on some particular GPU).
+    """
+
+    def __init__(self):
+        raise TypeError("Do not call Device's constructor directly, "
+                        "use the device attribute of the MemoryManager 
instead.")
+
+    cdef void init(self, const shared_ptr[CDevice]& device):
+        self.device = device
+
+    @staticmethod
+    cdef wrap(const shared_ptr[CDevice]& device):
+        cdef Device self = Device.__new__(Device)
+        self.init(device)
+        return self
+
+    def __eq__(self, other):
+        if not isinstance(other, Device):
+            return False
+        return self.device.get().Equals(deref((<Device>other).device.get()))
+
+    def __repr__(self):
+        return "<pyarrow.Device: 
{}>".format(frombytes(self.device.get().ToString()))
+
+    @property
+    def type_name(self):
+        """
+        A shorthand for this device's type.
+        """
+        return frombytes(self.device.get().type_name())
+
+    @property
+    def device_id(self):
+        """
+        A device ID to identify this device if there are multiple of this type.
+
+        If there is no "device_id" equivalent (such as for the main CPU device 
on
+        non-numa systems) returns -1.
+        """
+        return self.device.get().device_id()
+
+    @property
+    def is_cpu(self):
+        """
+        Whether this device is the main CPU device.
+
+        This shorthand method is very useful when deciding whether a memory 
address
+        is CPU-accessible.
+        """
+        return self.device.get().is_cpu()
+
+    @property
+    def device_type(self):
+        """
+        Return the DeviceAllocationType of this device.
+        """
+        return _wrap_device_allocation_type(self.device.get().device_type())
+
+
+cdef class MemoryManager(_Weakrefable):
+    """
+    An object that provides memory management primitives.
+
+    A MemoryManager is always tied to a particular Device instance.
+    It can also have additional parameters (such as a MemoryPool to
+    allocate CPU memory).
+
+    """
+
+    def __init__(self):
+        raise TypeError("Do not call MemoryManager's constructor directly, "
+                        "use pyarrow.default_cpu_memory_manager() instead.")
+
+    cdef void init(self, const shared_ptr[CMemoryManager]& mm):
+        self.memory_manager = mm
+
+    @staticmethod
+    cdef wrap(const shared_ptr[CMemoryManager]& mm):
+        cdef MemoryManager self = MemoryManager.__new__(MemoryManager)
+        self.init(mm)
+        return self
+
+    def __repr__(self):
+        return "<pyarrow.MemoryManager device: {}>".format(
+            frombytes(self.memory_manager.get().device().get().ToString())
+        )
+
+    @property
+    def device(self):
+        """
+        The device this MemoryManager is tied to.
+        """
+        return Device.wrap(self.memory_manager.get().device())
+
+    @property
+    def is_cpu(self):
+        """
+        Whether this MemoryManager is tied to the main CPU device.
+
+        This shorthand method is very useful when deciding whether a memory
+        address is CPU-accessible.
+        """
+        return self.memory_manager.get().is_cpu()
+
+
+def default_cpu_memory_manager():
+    """
+    Return the default CPU MemoryManager instance.
+
+    The returned singleton instance uses the default MemoryPool.
+    """
+    return MemoryManager.wrap(c_default_cpu_memory_manager())

Review Comment:
   Not necessarily, for now, if not needed? For CPU I am not sure if it is 
worth it, as looking at device.h, it seems the main thing the subclass provides 
is allowing to specify a memory pool when creating (which we could also expose 
through `default_cpu_memory_manager` if we want to expose this? 
   For CUDA there might be more CUDA-specific methods/attributes where it might 
be more worth providing a subclass.



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