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Co-authored-by: Tianyu Liu <[email protected]>

cpp/src/io/orc/reader_impl_chunking.cu

@@ -523,15 +523,12 @@ void reader_impl::load_next_stripe_data(read_mode mode)
     }
   }
   std::vector<std::unique_ptr<cudf::io::datasource::buffer>> host_read_buffers;
-  for (auto& task : host_read_tasks) {  // if there were host reads
-    host_read_buffers.emplace_back(std::get<0>(task).get());
+  for (auto& [fut, expected_size, dev_dst] : host_read_tasks) {  // if there were host reads
+    host_read_buffers.emplace_back(fut.get());
     auto* host_buffer = host_read_buffers.back().get();
-    CUDF_EXPECTS(host_buffer->size() == std::get<1>(task), "Unexpected discrepancy in bytes read.");
-    CUDF_CUDA_TRY(cudaMemcpyAsync(std::get<2>(task),
-                                  host_buffer->data(),
-                                  host_buffer->size(),
-                                  cudaMemcpyDefault,
-                                  _stream.value()));
+    CUDF_EXPECTS(host_buffer->size() == expected_size, "Unexpected discrepancy in bytes read.");
+    CUDF_CUDA_TRY(cudaMemcpyAsync(
+      dev_dst, host_buffer->data(), host_buffer->size(), cudaMemcpyDefault, _stream.value()));
   }
 
   for (auto& task : device_read_tasks) {  // if there were device reads

cpp/src/io/utilities/datasource.cpp

@@ -66,9 +66,9 @@ class kvikio_source : public datasource {
   kvikio_source(HandleT&& h) : _kvikio_handle(std::move(h)) {}
   std::unique_ptr<buffer> host_read(size_t offset, size_t size) override
   {
-    auto clamped_read = clamped_read_to_vector(offset, size);
-    clamped_read.second.get();
-    return buffer::create(std::move(clamped_read.first));
+    auto [v, fut] = clamped_read_to_vector(offset, size);
+    fut.get();
+    return buffer::create(std::move(v));
   }
 
   std::future<std::unique_ptr<datasource::buffer>> host_read_async(size_t offset,