cudf::column redesign

CHANGELOG.md

@@ -29,10 +29,12 @@
 - PR #2836 Add nvstrings.code_points method
 - PR #2844 Add Series/DataFrame notnull
 - PR #2858 Add GTest type list utilities
+- PR #2207 Beginning of libcudf overhaul: introduce new column and table types
 - PR #2838 CSV Reader: Support ARROW_RANDOM_FILE input
 - PR #2655 CuPy-based Series and Dataframe .values property
 - PR #2803 Added `edit_distance_matrix()` function to calculate pairwise edit distance for each string on a given nvstrings object.
 
+
 ## Improvements
 
 - PR #2578 Update legacy_groupby to use libcudf group_by_without_aggregation

cpp/CMakeLists.txt

@@ -417,7 +417,17 @@ add_library(cudf
             src/copying/copy_range.cu
             src/filling/fill.cu
             src/filling/repeat.cu
-            src/search/search.cu)
+            src/search/search.cu
+            src/column/column.cu
+            src/column/column_view.cpp
+            src/column/column_device_view.cu
+            src/column/column_factories.cpp
+            src/table/table_view.cpp
+            src/table/table_device_view.cu
+            src/table/table.cpp
+            src/bitmask/null_mask.cu
+            src/sort/sort.cu
+            src/column/legacy/interop.cpp)
 
 # Override RPATH for nvstrings
 set_target_properties(libNVStrings PROPERTIES BUILD_RPATH "\$ORIGIN")

cpp/include/cudf/column/column.hpp

@@ -0,0 +1,255 @@
+/*
+ * Copyright (c) 2019, 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/types.hpp>
+#include "column_view.hpp"
+
+#include <rmm/device_buffer.hpp>
+#include <rmm/mr/device_memory_resource.hpp>
+
+#include <memory>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+namespace cudf {
+
+class column {
+ public:
+  column() = default;
+  ~column() = default;
+  column& operator=(column const& other) = delete;
+  column& operator=(column&& other) = delete;
+
+  /**---------------------------------------------------------------------------*
+   * @brief Construct a new column by deep copying the contents of `other`.
+   *
+   * All device memory allocation and copying is done using the
+   * `device_memory_resource` and `stream` from `other`.
+   *
+   * @param other The column to copy
+   *---------------------------------------------------------------------------**/
+  column(column const& other);
+
+  /**---------------------------------------------------------------------------*
+   * @brief Construct a new column object by deep copying the contents of
+   *`other`.
+   *
+   * Uses the specified `stream` and device_memory_resource for all allocations
+   * and copies.
+   *
+   * @param other The `column` to copy
+   * @param stream The stream on which to execute all allocations and copies
+   * @param mr The resource to use for all allocations
+   *---------------------------------------------------------------------------**/
+  column(column const& other, cudaStream_t stream,
+         rmm::mr::device_memory_resource* mr = rmm::mr::get_default_resource());
+
+  /**---------------------------------------------------------------------------*
+   * @brief Move the contents from `other` to create a new column.
+   *
+   * After the move, `other.size() == 0` and `other.type() = {EMPTY}`
+   *
+   * @param other The column whose contents will be moved into the new column
+   *---------------------------------------------------------------------------**/
+  column(column&& other);
+
+  /**---------------------------------------------------------------------------*
+   * @brief Construct a new column from existing device memory.
+   *
+   * @note This constructor is primarily intended for use in column factory
+   * functions. 
+   *
+   * @param[in] dtype The element type
+   * @param[in] size The number of elements in the column
+   * @param[in] data The column's data
+   * @param[in] null_mask Optional, column's null value indicator bitmask. May
+   * be empty if `null_count` is 0 or `UNKNOWN_NULL_COUNT`.
+   * @param null_count Optional, the count of null elements. If unknown, specify
+   * `UNKNOWN_NULL_COUNT` to indicate that the null count should be computed on
+   * the first invocation of `null_count()`.
+   * @param children Optional, vector of child columns
+   *---------------------------------------------------------------------------**/
+  template <typename B1, typename B2 = rmm::device_buffer>
+  column(data_type dtype, size_type size, B1&& data, B2&& null_mask = {},
+         size_type null_count = UNKNOWN_NULL_COUNT,
+         std::vector<std::unique_ptr<column>>&& children = {})
+      : _type{dtype},
+        _size{size},
+        _data{std::forward<B1>(data)},
+        _null_mask{std::forward<B2>(null_mask)},
+        _null_count{null_count},
+        _children{std::move(children)} {}
+
+  /**---------------------------------------------------------------------------*
+   * @brief Construct a new column by deep copying the contents of a
+   * `column_view`.
+   *
+   * This accounts for the `column_view`'s offset.
+   *
+   * @param view The view to copy
+   * @param stream The stream on which all allocations and copies will be
+   * executed
+   * @param mr The resource to use for all allocations
+   *---------------------------------------------------------------------------**/
+  explicit column(
+      column_view view, cudaStream_t stream = 0,
+      rmm::mr::device_memory_resource* mr = rmm::mr::get_default_resource());
+
+  /**---------------------------------------------------------------------------*
+   * @brief Returns the column's logical element type
+   *---------------------------------------------------------------------------**/
+  data_type type() const noexcept { return _type; }
+
+  /**---------------------------------------------------------------------------*
+   * @brief Returns the number of elements
+   *---------------------------------------------------------------------------**/
+  size_type size() const noexcept { return _size; }
+
+  /**---------------------------------------------------------------------------*
+   * @brief Returns the count of null elements.
+   *
+   * @note If the column was constructed with `UNKNOWN_NULL_COUNT`, or if at any
+   * point `set_null_count(UNKNOWN_NULL_COUNT)` was invoked, then the
+   * first invocation of `null_count()` will compute and store the count of null
+   * elements indicated by the `null_mask` (if it exists).
+   *---------------------------------------------------------------------------**/
+  size_type null_count() const;
+
+  /**---------------------------------------------------------------------------*
+   * @brief Updates the count of null elements.
+   *
+   * @note `UNKNOWN_NULL_COUNT` can be specified as `new_null_count` to force
+   * the next invocation of `null_count()` to recompute the null count from the
+   * null mask.
+   *
+   * @throws cudf::logic_error if `new_null_count > 0 and nullable() == false`
+   *
+   * @param new_null_count The new null count.
+   *---------------------------------------------------------------------------**/
+  void set_null_count(size_type new_null_count);
+
+  /**---------------------------------------------------------------------------*
+   * @brief Indicates whether it is possible for the column to contain null
+   * values, i.e., it has an allocated null mask.
+   *
+   * This may return `false` iff `null_count() == 0`.
+   *
+   * May return true even if `null_count() == 0`. This function simply indicates
+   * whether the column has an allocated null mask.
+   *
+   * @return true The column can hold null values
+   * @return false The column cannot hold null values
+   *---------------------------------------------------------------------------**/
+  bool nullable() const noexcept { return (_null_mask.size() > 0); }
+
+  /**---------------------------------------------------------------------------*
+   * @brief Indicates whether the column contains null elements.
+   *
+   * @return true One or more elements are null
+   * @return false Zero elements are null
+   *---------------------------------------------------------------------------**/
+  bool has_nulls() const noexcept { return (null_count() > 0); }
+
+  /**---------------------------------------------------------------------------*
+   * @brief Returns the number of child columns
+   *---------------------------------------------------------------------------**/
+  size_type num_children() const noexcept { return _children.size(); }
+
+  /**---------------------------------------------------------------------------*
+   * @brief Returns a reference to the specified child
+   *
+   * @param child_index Index of the desired child
+   * @return column& Reference to the desired child
+   *---------------------------------------------------------------------------**/
+  column& child(size_type child_index) noexcept {
+    return *_children[child_index];
+  };
+
+  /**---------------------------------------------------------------------------*
+   * @brief Returns a const reference to the specified child
+   *
+   * @param child_index Index of the desired child
+   * @return column const& Const reference to the desired child
+   *---------------------------------------------------------------------------**/
+  column const& child(size_type child_index) const noexcept {
+    return *_children[child_index];
+  };
+
+  /**---------------------------------------------------------------------------*
+   * @brief Creates an immutable, non-owning view of the column's data and
+   * children.
+   *
+   * @return column_view The immutable, non-owning view
+   *---------------------------------------------------------------------------**/
+  column_view view() const;
+
+  /**---------------------------------------------------------------------------*
+   * @brief Implicit conversion operator to a `column_view`.
+   *
+   * This allows passing a `column` object directly into a function that
+   * requires a `column_view`. The conversion is automatic.
+   *
+   * @return column_view Immutable, non-owning `column_view`
+   *---------------------------------------------------------------------------**/
+  operator column_view() const { return this->view(); };
+
+  /**---------------------------------------------------------------------------*
+   * @brief Creates a mutable, non-owning view of the column's data and
+   * children.
+   *
+   * @note Creating a mutable view of a `column` invalidates the `column`'s
+   * `null_count()` by setting it to `UNKNOWN_NULL_COUNT`. The user can
+   * either explicitly update the null count with `set_null_count()`, or
+   * if not, the null count will be recomputed on the next invocation of
+   *`null_count()`.
+   *
+   * @return mutable_column_view The mutable, non-owning view
+   *---------------------------------------------------------------------------**/
+  mutable_column_view mutable_view();
+
+  /**---------------------------------------------------------------------------*
+   * @brief Implicit conversion operator to a `mutable_column_view`.
+   *
+   * This allows pasing a `column` object into a function that accepts a
+   *`mutable_column_view`. The conversion is automatic.
+
+   * @note Creating a mutable view of a `column` invalidates the `column`'s
+   * `null_count()` by setting it to `UNKNOWN_NULL_COUNT`. For best performance,
+   * the user should explicitly update the null count with `set_null_count()`.
+   * Otherwise, the null count will be recomputed on the next invocation of
+   * `null_count()`.
+   *
+   * @return mutable_column_view Mutable, non-owning `mutable_column_view`
+   *---------------------------------------------------------------------------**/
+  operator mutable_column_view() { return this->mutable_view(); };
+
+ private:
+  data_type _type{EMPTY};      ///< Logical type of elements in the column
+  cudf::size_type _size{};     ///< The number of elements in the column
+  rmm::device_buffer _data{};  ///< Dense, contiguous, type erased device memory
+                               ///< buffer containing the column elements
+  rmm::device_buffer _null_mask{};  ///< Bitmask used to represent null values.
+                                    ///< May be empty if `null_count() == 0`
+  mutable size_type _null_count{
+      UNKNOWN_NULL_COUNT};  ///< The number of null elements
+  std::vector<std::unique_ptr<column>>
+      _children{};  ///< Depending on element type, child
+                    ///< columns may contain additional data
+};
+
+}  // namespace cudf