ARROW-3316: [R] Multi-threaded conversion from R data.frame to Arrow table / record batch

r/R/table.R

@@ -168,17 +168,17 @@ Table$create <- function(..., schema = NULL) {
     names(dots) <- rep_len("", length(dots))
   }
   stopifnot(length(dots) > 0)
-  
+
   # Preserve any grouping
   if (length(dots) == 1 && inherits(dots[[1]], "grouped_df")) {
-    out <- Table__from_dots(dots, schema)
+    out <- Table__from_dots(dots, schema, option_use_threads())
     return(dplyr::group_by(out, !!!dplyr::groups(dots[[1]])))
   }
-  
+
   if (all_record_batches(dots)) {
     Table__from_record_batches(dots, schema)
   } else {
-    Table__from_dots(dots, schema)
+    Table__from_dots(dots, schema, option_use_threads())
   }
 }
 

r/src/arrow_types.h

@@ -149,6 +149,14 @@ void TraverseDots(cpp11::list dots, int num_fields, Lambda lambda) {
   }
 }
 
+inline cpp11::writable::list FlattenDots(cpp11::list dots, int num_fields) {
+  std::vector<SEXP> out(num_fields);
+  auto set = [&](int j, SEXP x, cpp11::r_string) { out[j] = x; };
+  TraverseDots(dots, num_fields, set);
+
+  return cpp11::writable::list(out.begin(), out.end());
+}
+
 arrow::Status InferSchemaFromDots(SEXP lst, SEXP schema_sxp, int num_fields,
                                   std::shared_ptr<arrow::Schema>& schema);
 

r/src/csv.cpp

@@ -22,7 +22,6 @@
 #include <arrow/csv/reader.h>
 #include <arrow/csv/writer.h>
 #include <arrow/memory_pool.h>
-
 #include <arrow/util/value_parsing.h>
 
 // [[arrow::export]]