Add placeholder for the experimental JSON reader (NVIDIA#11334)

Adds a new boolean option to libcudf `json_reader_options` - `experimental` (defaults to `false`).
When the experimental reader is selected a placeholder implementation is called that simply fails for now.

Authors:
  - Vukasin Milovanovic (https://github.com/vuule)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - GALI PREM SAGAR (https://github.com/galipremsagar)
  - Yunsong Wang (https://github.com/PointKernel)
  - Nghia Truong (https://github.com/ttnghia)

URL: rapidsai/cudf#11334

cpp/CMakeLists.txt

@@ -323,6 +323,7 @@ add_library(
   src/io/functions.cpp
   src/io/json/json_gpu.cu
   src/io/json/reader_impl.cu
+  src/io/json/experimental/read_json.cpp
   src/io/orc/aggregate_orc_metadata.cpp
   src/io/orc/dict_enc.cu
   src/io/orc/orc.cpp

cpp/include/cudf/io/json.hpp

@@ -80,6 +80,9 @@ class json_reader_options {
   // Whether to parse dates as DD/MM versus MM/DD
   bool _dayfirst = false;
 
+  // Whether to use the experimental reader
+  bool _experimental = false;
+
   /**
    * @brief Constructor from source info.
    *
@@ -193,6 +196,13 @@ class json_reader_options {
    */
   bool is_enabled_dayfirst() const { return _dayfirst; }
 
+  /**
+   * @brief Whether the experimental reader should be used.
+   *
+   * @returns true if the experimental reader will be used, false otherwise
+   */
+  bool is_enabled_experimental() const { return _experimental; }
+
   /**
    * @brief Set data types for columns to be read.
    *
@@ -241,6 +251,13 @@ class json_reader_options {
    * @param val Boolean value to enable/disable day first parsing format
    */
   void enable_dayfirst(bool val) { _dayfirst = val; }
+
+  /**
+   * @brief Set whether to use the experimental reader.
+   *
+   * @param val Boolean value to enable/disable the experimental reader
+   */
+  void enable_experimental(bool val) { _experimental = val; }
 };
 
 /**
@@ -348,6 +365,18 @@ class json_reader_options_builder {
     return *this;
   }
 
+  /**
+   * @brief Set whether to use the experimental reader.
+   *
+   * @param val Boolean value to enable/disable experimental parsing
+   * @return this for chaining
+   */
+  json_reader_options_builder& experimental(bool val)
+  {
+    options._experimental = val;
+    return *this;
+  }
+
   /**
    * @brief move json_reader_options member once it's built.
    */

cpp/src/io/json/experimental/read_json.cpp

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2022, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "read_json.hpp"
+
+#include <cudf/utilities/error.hpp>
+
+namespace cudf::io::detail::json::experimental {
+
+table_with_metadata read_json(host_span<std::unique_ptr<datasource>> sources,
+                              json_reader_options const& reader_opts,
+                              rmm::cuda_stream_view stream,
+                              rmm::mr::device_memory_resource* mr)
+{
+  CUDF_FAIL("Not implemented");
+}
+
+}  // namespace cudf::io::detail::json::experimental

cpp/src/io/json/experimental/read_json.hpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2022, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <cudf/io/datasource.hpp>
+#include <cudf/io/json.hpp>
+#include <cudf/types.hpp>
+#include <cudf/utilities/span.hpp>
+
+#include <rmm/cuda_stream_view.hpp>
+#include <rmm/mr/device/device_memory_resource.hpp>
+
+#include <memory>
+
+namespace cudf::io::detail::json::experimental {
+
+table_with_metadata read_json(host_span<std::unique_ptr<datasource>> sources,
+                              json_reader_options const& reader_opts,
+                              rmm::cuda_stream_view stream,
+                              rmm::mr::device_memory_resource* mr);
+
+}

cpp/src/io/json/reader_impl.cu

@@ -16,6 +16,8 @@
 
 #include "json_gpu.hpp"
 
+#include "experimental/read_json.hpp"
+
 #include <hash/concurrent_unordered_map.cuh>
 
 #include <io/comp/io_uncomp.hpp>
@@ -571,6 +573,10 @@ table_with_metadata read_json(std::vector<std::unique_ptr<datasource>>& sources,
                               rmm::cuda_stream_view stream,
                               rmm::mr::device_memory_resource* mr)
 {
+  if (reader_opts.is_enabled_experimental()) {
+    return experimental::read_json(sources, reader_opts, stream, mr);
+  }
+
   CUDF_EXPECTS(not sources.empty(), "No sources were defined");
 
   CUDF_EXPECTS(reader_opts.is_enabled_lines(), "Only JSON Lines format is currently supported.\n");