(arrow) branch main updated: GH-39159 [C++]: Try to make Buffer::device_type_ non-optional (#39150)

[felipecrv]

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The following commit(s) were added to refs/heads/main by this push:
     new 595b37ceba GH-39159 [C++]: Try to make Buffer::device_type_ 
non-optional (#39150)
595b37ceba is described below

commit 595b37ceba52e74cda72a7073ab31fe637b16ee2
Author: Felipe Oliveira Carvalho <felipe...@gmail.com>
AuthorDate: Mon Dec 11 11:55:46 2023 -0300

    GH-39159 [C++]: Try to make Buffer::device_type_ non-optional (#39150)
    
    ### Rationale for this change
    
    Buffer should always have a device type. When unspecified, CPU can be 
assumed.
    
    ### What changes are included in this PR?
    
    A change of the member variable type and some adjustments.
    
    ### Are these changes tested?
    
    N/A.
    
    ### Are there any user-facing changes?
    
    **This PR includes breaking changes to public APIs.**
    
    `Buffer::device_type_` is now a `DeviceAllocationType` instead of a 
`std::optional<DeviceAllocationType>`.
    * Closes: #39159
    
    Authored-by: Felipe Oliveira Carvalho <felipe...@gmail.com>
    Signed-off-by: Felipe Oliveira Carvalho <felipe...@gmail.com>
---
 cpp/src/arrow/buffer.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/cpp/src/arrow/buffer.h b/cpp/src/arrow/buffer.h
index 7cc2d2c9cc..ae76550be2 100644
--- a/cpp/src/arrow/buffer.h
+++ b/cpp/src/arrow/buffer.h
@@ -70,7 +70,7 @@ class ARROW_EXPORT Buffer {
 
   Buffer(const uint8_t* data, int64_t size, std::shared_ptr<MemoryManager> mm,
          std::shared_ptr<Buffer> parent = NULLPTR,
-         std::optional<DeviceAllocationType> device_type = std::nullopt)
+         std::optional<DeviceAllocationType> device_type_override = 
std::nullopt)
       : is_mutable_(false),
         data_(data),
         size_(size),
@@ -78,11 +78,11 @@ class ARROW_EXPORT Buffer {
         parent_(std::move(parent)) {
     // SetMemoryManager will also set device_type_
     SetMemoryManager(std::move(mm));
-    // if a device type is specified, use that instead. for example:
-    // CUDA_HOST. The CudaMemoryManager will set device_type_ to CUDA,
-    // but you can specify CUDA_HOST as the device type to override it.
-    if (device_type != std::nullopt) {
-      device_type_ = device_type;
+    // If a device type is specified, use that instead. Example of when this 
can be
+    // useful: the CudaMemoryManager can set device_type_ to kCUDA, but you 
can specify
+    // device_type_override=kCUDA_HOST as the device type to override it.
+    if (device_type_override != std::nullopt) {
+      device_type_ = *device_type_override;
     }
   }
 
@@ -296,7 +296,7 @@ class ARROW_EXPORT Buffer {
 
   const std::shared_ptr<MemoryManager>& memory_manager() const { return 
memory_manager_; }
 
-  std::optional<DeviceAllocationType> device_type() const { return 
device_type_; }
+  DeviceAllocationType device_type() const { return device_type_; }
 
   std::shared_ptr<Buffer> parent() const { return parent_; }
 
@@ -354,7 +354,7 @@ class ARROW_EXPORT Buffer {
   const uint8_t* data_;
   int64_t size_;
   int64_t capacity_;
-  std::optional<DeviceAllocationType> device_type_;
+  DeviceAllocationType device_type_;
 
   // null by default, but may be set
   std::shared_ptr<Buffer> parent_;