zeroshade commented on code in PR #39770:
URL: https://github.com/apache/arrow/pull/39770#discussion_r1470153660
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cpp/src/arrow/c/bridge.cc:
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@@ -1851,10 +1853,25 @@ struct ArrayImporter {
template <typename OffsetType>
Status ImportStringValuesBuffer(int32_t offsets_buffer_id, int32_t buffer_id,
int64_t byte_width = 1) {
- auto offsets = data_->GetValues<OffsetType>(offsets_buffer_id);
+ if (device_type_ == DeviceAllocationType::kCPU) {
+ auto offsets = data_->GetValues<OffsetType>(offsets_buffer_id);
+ // Compute visible size of buffer
+ int64_t buffer_size =
+ (c_struct_->length > 0) ? byte_width * offsets[c_struct_->length] :
0;
+ return ImportBuffer(buffer_id, buffer_size);
+ }
+
+ // we only need the value of the last offset so let's just copy that
+ // one value from device to host.
+ auto single_value_buf =
+ SliceBuffer(data_->buffers[offsets_buffer_id],
+ c_struct_->length * sizeof(OffsetType),
sizeof(OffsetType));
+ ARROW_ASSIGN_OR_RAISE(
+ auto cpubuf, Buffer::ViewOrCopy(single_value_buf,
default_cpu_memory_manager()));
+ auto offsets = cpubuf->data_as<OffsetType>();
Review Comment:
Possibly, I didn't necessarily want to make this that large by adding to the
`MemoryManager` interface, but it's definitely a good idea to do in the future.
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