Add #pragma once to prevent redundant includes and speed up compilation (#18925)

Discovered while working on #18896, this PR adds `#pragma once` directives to eliminate redundant header inclusions and reduce compilation time.

Authors:
  - Yunsong Wang (https://github.com/PointKernel)
  - Bradley Dice (https://github.com/bdice)

Approvers:
  - David Wendt (https://github.com/davidwendt)
  - Nghia Truong (https://github.com/ttnghia)
  - Bradley Dice (https://github.com/bdice)

URL: #18925

Author: PointKernel

cpp/benchmarks/ndsh/utilities.hpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include "io/cuio_common.hpp"
 
 #include <cudf/detail/nvtx/ranges.hpp>

cpp/benchmarks/stream_compaction/stream_compaction_common.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2020-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <cudf/stream_compaction.hpp>
 
 cudf::duplicate_keep_option get_keep(std::string const& keep_str);

cpp/examples/utilities/timer.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, NVIDIA CORPORATION.
+ * Copyright (c) 2024-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <chrono>
 #include <iostream>
 

cpp/include/cudf/detail/labeling/label_segments.cuh

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <cudf/types.hpp>
 
 #include <rmm/cuda_stream_view.hpp>

cpp/include/cudf/detail/utilities/batched_memcpy.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, NVIDIA CORPORATION.
+ * Copyright (c) 2024-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <cudf/detail/iterator.cuh>
 #include <cudf/utilities/memory_resource.hpp>
 

cpp/include/cudf/detail/utilities/batched_memset.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, NVIDIA CORPORATION.
+ * Copyright (c) 2024-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <cudf/detail/iterator.cuh>
 #include <cudf/detail/utilities/vector_factories.hpp>
 #include <cudf/utilities/memory_resource.hpp>

cpp/include/cudf/detail/utilities/host_worker_pool.hpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <BS_thread_pool.hpp>
 
 namespace cudf::detail {

cpp/include/cudf/strings/detail/convert/string_to_float.cuh

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <cudf/strings/detail/convert/is_float.cuh>
 #include <cudf/strings/string_view.cuh>
 

cpp/src/hash/sha_hash.cuh

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, NVIDIA CORPORATION.
+ * Copyright (c) 2024-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,6 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+#pragma once
+
 #include <cudf/column/column_device_view.cuh>
 #include <cudf/column/column_factories.hpp>
 #include <cudf/detail/iterator.cuh>

cpp/src/io/utilities/output_builder.cuh

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <cudf/types.hpp>
 #include <cudf/utilities/error.hpp>
 #include <cudf/utilities/memory_resource.hpp>