Explicitly use the current device resource in DeviceBuffer

Previously we were relying on the C++ and Python-level device
resources to agree. But this need not be the case.

To avoid this, first get the current deivce resource and then use it
when allocating the wrapped C++ device_buffer when creating
DeviceBuffers.

- Closes #1506

Author: wence-

python/rmm/_lib/device_buffer.pxd

@@ -17,17 +17,31 @@ from libcpp.memory cimport unique_ptr
 
 from rmm._cuda.stream cimport Stream
 from rmm._lib.cuda_stream_view cimport cuda_stream_view
-from rmm._lib.memory_resource cimport DeviceMemoryResource
+from rmm._lib.memory_resource cimport (
+    DeviceMemoryResource,
+    device_memory_resource,
+)
 
 
 cdef extern from "rmm/device_buffer.hpp" namespace "rmm" nogil:
     cdef cppclass device_buffer:
         device_buffer()
-        device_buffer(size_t size, cuda_stream_view stream) except +
-        device_buffer(const void* source_data,
-                      size_t size, cuda_stream_view stream) except +
-        device_buffer(const device_buffer buf,
-                      cuda_stream_view stream) except +
+        device_buffer(
+            size_t size,
+            cuda_stream_view stream,
+            device_memory_resource *
+        ) except +
+        device_buffer(
+            const void* source_data,
+            size_t size,
+            cuda_stream_view stream,
+            device_memory_resource *
+        ) except +
+        device_buffer(
+            const device_buffer buf,
+            cuda_stream_view stream,
+            device_memory_resource *
+        ) except +
         void reserve(size_t new_capacity, cuda_stream_view stream) except +
         void resize(size_t new_size, cuda_stream_view stream) except +
         void shrink_to_fit(cuda_stream_view stream) except +

python/rmm/_lib/device_buffer.pyx

@@ -32,7 +32,10 @@ from cuda.ccudart cimport (
     cudaStream_t,
 )
 
-from rmm._lib.memory_resource cimport get_current_device_resource
+from rmm._lib.memory_resource cimport (
+    device_memory_resource,
+    get_current_device_resource,
+)
 
 
 # The DeviceMemoryResource attribute could be released prematurely
@@ -75,22 +78,21 @@ cdef class DeviceBuffer:
         >>> db = rmm.DeviceBuffer(size=5)
         """
         cdef const void* c_ptr
-
+        cdef device_memory_resource * mr_ptr
+        # Save a reference to the MR and stream used for allocation
+        self.mr = get_current_device_resource()
+        mr_ptr = self.mr.get_mr()
         with nogil:
             c_ptr = <const void*>ptr
 
-            if size == 0:
-                self.c_obj.reset(new device_buffer())
-            elif c_ptr == NULL:
-                self.c_obj.reset(new device_buffer(size, stream.view()))
+            if c_ptr == NULL or size == 0:
+                self.c_obj.reset(new device_buffer(size, stream.view(), mr_ptr))
             else:
-                self.c_obj.reset(new device_buffer(c_ptr, size, stream.view()))
+                self.c_obj.reset(new device_buffer(c_ptr, size, stream.view(), mr_ptr))
 
                 if stream.c_is_default():
                     stream.c_synchronize()
 
-        # Save a reference to the MR and stream used for allocation
-        self.mr = get_current_device_resource()
         self.stream = stream
 
     def __len__(self):

python/rmm/_lib/memory_resource.pxd

@@ -34,7 +34,7 @@ cdef extern from "rmm/mr/device/device_memory_resource.hpp" \
 
 cdef class DeviceMemoryResource:
     cdef shared_ptr[device_memory_resource] c_obj
-    cdef device_memory_resource* get_mr(self)
+    cdef device_memory_resource* get_mr(self) noexcept nogil
 
 cdef class UpstreamResourceAdaptor(DeviceMemoryResource):
     cdef readonly DeviceMemoryResource upstream_mr

python/rmm/_lib/memory_resource.pyx

@@ -218,7 +218,7 @@ cdef extern from "rmm/mr/device/failure_callback_resource_adaptor.hpp" \
 
 cdef class DeviceMemoryResource:
 
-    cdef device_memory_resource* get_mr(self):
+    cdef device_memory_resource* get_mr(self) noexcept nogil:
         """Get the underlying C++ memory resource object."""
         return self.c_obj.get()