Add API to count number of deleted rows across deletion vector(s)

cpp/CMakeLists.txt

@@ -530,6 +530,7 @@ add_library(
   src/io/parquet/decode_preprocess.cu
   src/io/parquet/experimental/dictionary_page_filter.cu
   src/io/parquet/experimental/deletion_vectors.cu
+  src/io/parquet/experimental/deletion_vectors_helpers.cu
   src/io/parquet/experimental/hybrid_scan.cpp
   src/io/parquet/experimental/hybrid_scan_chunking.cu
   src/io/parquet/experimental/hybrid_scan_helpers.cpp

cpp/include/cudf/io/experimental/deletion_vectors.hpp

@@ -178,6 +178,20 @@ table_with_metadata read_parquet(
   rmm::cuda_stream_view stream      = cudf::get_default_stream(),
   rmm::device_async_resource_ref mr = rmm::mr::get_current_device_resource_ref());
 
+/**
+ * @brief Computes the number of rows deleted by the serialized 64-bit roaring bitmap deletion
+ * vectors
+ *
+ * @param deletion_vector_info Information about the deletion vectors and the index column
+ * @param max_chunk_rows Maximum number of rows to process at a time
+ * @param stream CUDA stream used for device memory operations and kernel launches
+ * @return Number of rows deleted by the specified 64-bit roaring bitmap deletion vectors
+ */
+[[nodiscard]] size_t compute_num_deleted_rows(
+  deletion_vector_info const& deletion_vector_info,
+  cudf::size_type max_chunk_rows = std::numeric_limits<size_type>::max(),
+  rmm::cuda_stream_view stream   = cudf::get_default_stream());
+
 /** @} */  // end of group
 
 }  // namespace io::parquet::experimental