icexelloss commented on code in PR #34311:
URL: https://github.com/apache/arrow/pull/34311#discussion_r1123745030
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cpp/src/arrow/compute/row/grouper.cc:
##########
@@ -39,12 +43,336 @@
namespace arrow {
using internal::checked_cast;
+using internal::PrimitiveScalarBase;
namespace compute {
namespace {
-struct GrouperImpl : Grouper {
+constexpr uint32_t kNoGroupId = std::numeric_limits<uint32_t>::max();
+
+using group_id_t = std::remove_const<decltype(kNoGroupId)>::type;
+using GroupIdType = CTypeTraits<group_id_t>::ArrowType;
+auto g_group_id_type = std::make_shared<GroupIdType>();
+
+inline const uint8_t* GetValuesAsBytes(const ArraySpan& data, int64_t offset =
0) {
+ DCHECK_GT(data.type->byte_width(), 0);
+ int64_t absolute_byte_offset = (data.offset + offset) *
data.type->byte_width();
+ return data.GetValues<uint8_t>(1, absolute_byte_offset);
+}
+
+template <typename Value>
+Status CheckForGetNextSegment(const std::vector<Value>& values, int64_t length,
+ int64_t offset, const std::vector<TypeHolder>&
key_types) {
+ if (offset < 0 || offset > length) {
+ return Status::Invalid("invalid grouping segmenter offset: ", offset);
+ }
+ if (values.size() != key_types.size()) {
+ return Status::Invalid("expected batch size ", key_types.size(), " but got
",
+ values.size());
+ }
+ for (size_t i = 0; i < key_types.size(); i++) {
+ const auto& value = values[i];
+ const auto& key_type = key_types[i];
+ if (*value.type() != *key_type.type) {
+ return Status::Invalid("expected batch value ", i, " of type ",
*key_type.type,
+ " but got ", *value.type());
+ }
+ }
+ return Status::OK();
+}
+
+template <typename Batch>
+enable_if_t<std::is_same<Batch, ExecSpan>::value || std::is_same<Batch,
ExecBatch>::value,
+ Status>
+CheckForGetNextSegment(const Batch& batch, int64_t offset,
+ const std::vector<TypeHolder>& key_types) {
+ return CheckForGetNextSegment(batch.values, batch.length, offset, key_types);
+}
+
+struct BaseGroupingSegmenter : public GroupingSegmenter {
+ explicit BaseGroupingSegmenter(const std::vector<TypeHolder>& key_types)
+ : key_types_(key_types) {}
+
+ const std::vector<TypeHolder>& key_types() const override { return
key_types_; }
+
+ std::vector<TypeHolder> key_types_;
+};
+
+GroupingSegment MakeSegment(int64_t batch_length, int64_t offset, int64_t
length,
+ bool extends) {
+ return GroupingSegment{offset, length, offset + length >= batch_length,
extends};
+}
+
+int64_t GetMatchLength(const uint8_t* match_bytes, int64_t match_width,
+ const uint8_t* array_bytes, int64_t offset, int64_t
length) {
+ int64_t cursor, byte_cursor;
+ for (cursor = offset, byte_cursor = match_width * cursor; cursor < length;
+ cursor++, byte_cursor += match_width) {
+ if (memcmp(match_bytes, array_bytes + byte_cursor,
+ static_cast<size_t>(match_width)) != 0) {
+ break;
+ }
+ }
+ return std::min(cursor, length - offset);
+}
+
+using ExtendFunc = std::function<bool(const void*)>;
+constexpr bool kDefaultExtends = true;
+constexpr bool kEmptyExtends = true;
+
+struct NoKeysGroupingSegmenter : public BaseGroupingSegmenter {
+ static std::unique_ptr<GroupingSegmenter> Make() {
+ return std::make_unique<NoKeysGroupingSegmenter>();
+ }
+
+ NoKeysGroupingSegmenter() : BaseGroupingSegmenter({}) {}
+
+ Status Reset() override { return Status::OK(); }
+
+ Result<GroupingSegment> GetNextSegment(const ExecSpan& batch, int64_t
offset) override {
+ ARROW_RETURN_NOT_OK(CheckForGetNextSegment(batch, offset, {}));
+ return MakeSegment(batch.length, offset, batch.length - offset,
kDefaultExtends);
+ }
+};
+
+struct SimpleKeyGroupingSegmenter : public BaseGroupingSegmenter {
+ static Result<std::unique_ptr<GroupingSegmenter>> Make(TypeHolder key_type) {
+ return std::make_unique<SimpleKeyGroupingSegmenter>(key_type);
+ }
+
+ explicit SimpleKeyGroupingSegmenter(TypeHolder key_type)
+ : BaseGroupingSegmenter({key_type}), key_type_(key_types_[0]),
save_key_data_() {}
+
+ Status CheckType(const DataType& type) {
+ if (!is_fixed_width(type)) {
+ return Status::Invalid("SimpleKeyGroupingSegmenter does not support type
", type);
+ }
+ return Status::OK();
+ }
+
+ Status Reset() override {
+ save_key_data_.resize(0);
+ return Status::OK();
+ }
+
+ // Checks whether the given grouping data extends the current segment, i.e.,
is equal to
+ // previously seen grouping data, which is updated with each invocation.
+ bool Extend(const void* data) {
+ size_t byte_width = static_cast<size_t>(key_type_.type->byte_width());
+ bool extends = save_key_data_.size() != byte_width
+ ? kDefaultExtends
+ : 0 == memcmp(save_key_data_.data(), data, byte_width);
+ save_key_data_.resize(byte_width);
+ memcpy(save_key_data_.data(), data, byte_width);
+ return extends;
+ }
+
+ Result<GroupingSegment> GetNextSegment(const Scalar& scalar, int64_t offset,
+ int64_t length) {
+ ARROW_RETURN_NOT_OK(CheckType(*scalar.type));
+ if (!scalar.is_valid) {
+ return Status::Invalid("segmenting an invalid scalar");
+ }
+ auto data = checked_cast<const PrimitiveScalarBase&>(scalar).data();
+ bool extends = length > 0 ? Extend(data) : kEmptyExtends;
+ return MakeSegment(length, offset, length, extends);
+ }
+
+ Result<GroupingSegment> GetNextSegment(const DataType& array_type,
+ const uint8_t* array_bytes, int64_t
offset,
+ int64_t length) {
+ RETURN_NOT_OK(CheckType(array_type));
+ int64_t byte_width = array_type.byte_width();
+ int64_t match_length = GetMatchLength(array_bytes + offset * byte_width,
byte_width,
+ array_bytes, offset, length);
+ bool extends = length > 0 ? Extend(array_bytes + offset * byte_width) :
kEmptyExtends;
+ return MakeSegment(length, offset, match_length, extends);
+ }
+
+ Result<GroupingSegment> GetNextSegment(const ExecSpan& batch, int64_t
offset) override {
+ ARROW_RETURN_NOT_OK(CheckForGetNextSegment(batch, offset, {key_type_}));
+ if (offset == batch.length) {
+ return MakeSegment(batch.length, offset, 0, kEmptyExtends);
+ }
+ const auto& value = batch.values[0];
+ if (value.is_scalar()) {
+ return GetNextSegment(*value.scalar, offset, batch.length);
+ }
+ ARROW_DCHECK(value.is_array());
+ const auto& array = value.array;
+ if (array.GetNullCount() > 0) {
+ return Status::NotImplemented("segmenting a nullable array");
+ }
+ return GetNextSegment(*array.type, GetValuesAsBytes(array), offset,
batch.length);
+ }
+
+ private:
+ TypeHolder key_type_;
+ std::vector<uint8_t> save_key_data_;
+};
+
+struct AnyKeysGroupingSegmenter : public BaseGroupingSegmenter {
+ static Result<std::unique_ptr<GroupingSegmenter>> Make(
+ const std::vector<TypeHolder>& key_types, ExecContext* ctx) {
+ ARROW_RETURN_NOT_OK(Grouper::Make(key_types, ctx)); // check types
+ return std::make_unique<AnyKeysGroupingSegmenter>(key_types, ctx);
+ }
+
+ AnyKeysGroupingSegmenter(const std::vector<TypeHolder>& key_types,
ExecContext* ctx)
+ : BaseGroupingSegmenter(key_types),
+ ctx_(ctx),
+ grouper_(nullptr),
+ save_group_id_(kNoGroupId) {}
+
+ Status Reset() override {
+ grouper_ = nullptr;
+ save_group_id_ = kNoGroupId;
+ return Status::OK();
+ }
+
+ bool Extend(const void* data) {
+ auto group_id = *static_cast<const group_id_t*>(data);
+ bool extends =
+ save_group_id_ == kNoGroupId ? kDefaultExtends : save_group_id_ ==
group_id;
+ save_group_id_ = group_id;
+ return extends;
+ }
+
+ // Runs the grouper on a single row. This is used to determine the group id
of the
+ // first row of a new segment to see if it extends the previous segment.
+ template <typename Batch>
+ Result<group_id_t> MapGroupIdAt(const Batch& batch, int64_t offset) {
+ if (!grouper_) return kNoGroupId;
+ ARROW_ASSIGN_OR_RAISE(auto datum, grouper_->Consume(batch, offset,
+ /*consume_length=*/1));
+ if (!datum.is_array()) {
+ return Status::Invalid("accessing unsupported datum kind ",
datum.kind());
+ }
+ const std::shared_ptr<ArrayData>& data = datum.array();
+ ARROW_DCHECK(data->GetNullCount() == 0);
+ DCHECK_EQ(data->type->id(), GroupIdType::type_id);
+ DCHECK_EQ(1, data->length);
+ const group_id_t* values = data->GetValues<group_id_t>(1);
+ return values[0];
+ }
+
+ Result<GroupingSegment> GetNextSegment(const ExecSpan& batch, int64_t
offset) override {
+ ARROW_RETURN_NOT_OK(CheckForGetNextSegment(batch, offset, key_types_));
+ if (offset == batch.length) {
+ return MakeSegment(batch.length, offset, 0, kEmptyExtends);
+ }
+ // ARROW-18311: make Grouper support Reset()
+ // so it can be cached instead of recreated below
+ //
+ // the group id must be computed prior to resetting the grouper, since it
is compared
+ // to save_group_id_, and after resetting the grouper produces
incomparable group ids
+ ARROW_ASSIGN_OR_RAISE(auto group_id, MapGroupIdAt(batch, offset));
+ ExtendFunc bound_extend = [this, group_id](const void* data) {
+ bool extends = Extend(&group_id);
+ save_group_id_ = *static_cast<const group_id_t*>(data);
+ return extends;
+ };
+ ARROW_ASSIGN_OR_RAISE(grouper_, Grouper::Make(key_types_, ctx_)); //
TODO: reset it
+ ARROW_ASSIGN_OR_RAISE(auto datum, grouper_->Consume(batch, offset));
+ if (datum.is_array()) {
+ const std::shared_ptr<ArrayData>& data = datum.array();
+ ARROW_DCHECK(data->GetNullCount() == 0);
+ DCHECK_EQ(data->type->id(), GroupIdType::type_id);
+ const group_id_t* values = data->GetValues<group_id_t>(1);
+ int64_t cursor;
+ for (cursor = 1; cursor < data->length; cursor++) {
+ if (values[0] != values[cursor]) break;
+ }
+ int64_t length = std::min(cursor, batch.length - offset);
+ bool extends = length > 0 ? bound_extend(values) : kEmptyExtends;
+ return MakeSegment(batch.length, offset, length, extends);
+ } else {
+ return Status::Invalid("segmenting unsupported datum kind ",
datum.kind());
+ }
+ }
+
+ private:
+ ExecContext* const ctx_;
+ std::unique_ptr<Grouper> grouper_;
+ group_id_t save_group_id_;
+};
+
+Status CheckForConsume(int64_t batch_length, int64_t& consume_offset,
+ int64_t* consume_length) {
+ if (consume_offset < 0) {
+ return Status::Invalid("invalid grouper consume offset: ", consume_offset);
+ }
+ if (*consume_length < 0) {
+ *consume_length = batch_length - consume_offset;
Review Comment:
This looks scary that this method would change the `length` - why are we
doing this?
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