ParquetTimestampEncoder.h

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/*
 * Copyright 2020 OmniSci, Inc.
 *
 * 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 "ParquetInPlaceEncoder.h"

namespace foreign_storage {

// The following semantics apply to the templated types below.
//
// V - type of omnisci data
// T - physical type of parquet data
// conversion_denominator - the denominator constant used in converting parquet to omnisci
// data
//
// The `conversion_denominator` template is used instead of a class member to
// specify it at compile-time versus run-time. In testing this has a major
// impact on the runtime of the conversion performed by this encoder since the
// compiler can significantly optimize if this is known at compile time.
template <typename V, typename T, T conversion_denominator>
class ParquetTimestampEncoder : public TypedParquetInPlaceEncoder<V, T>,
                                public ParquetMetadataValidator {
 public:
  ParquetTimestampEncoder(Data_Namespace::AbstractBuffer* buffer,
                          const ColumnDescriptor* column_desciptor,
                          const parquet::ColumnDescriptor* parquet_column_descriptor)
      : TypedParquetInPlaceEncoder<V, T>(buffer,
                                         column_desciptor,
                                         parquet_column_descriptor) {
    CHECK(parquet_column_descriptor->logical_type()->is_timestamp());
  }

  void encodeAndCopy(const int8_t* parquet_data_bytes,
                     int8_t* omnisci_data_bytes) override {
    const auto& parquet_data_value = reinterpret_cast<const T*>(parquet_data_bytes)[0];
    auto& omnisci_data_value = reinterpret_cast<V*>(omnisci_data_bytes)[0];
    omnisci_data_value = convert(parquet_data_value);
  }

  void validate(std::shared_ptr<parquet::Statistics> stats,
                const SQLTypeInfo& column_type) const override {
    CHECK(column_type.is_timestamp() || column_type.is_date());
    auto [unencoded_stats_min, unencoded_stats_max] =
        TypedParquetInPlaceEncoder<V, T>::getUnencodedStats(stats);
    if (column_type.is_timestamp()) {
      TimestampBoundsValidator<T>::validateValue(
          unencoded_stats_max, convert(unencoded_stats_max), column_type);
      TimestampBoundsValidator<T>::validateValue(
          unencoded_stats_min, convert(unencoded_stats_min), column_type);
    } else if (column_type.is_date()) {
      DateInSecondsBoundsValidator<T>::validateValue(convert(unencoded_stats_max),
                                                     column_type);
      DateInSecondsBoundsValidator<T>::validateValue(convert(unencoded_stats_min),
                                                     column_type);
    }
  }

 private:
  T convert(const T& value) const {
    T quotient = value / conversion_denominator;
    return value < 0 && (value % conversion_denominator != 0) ? quotient - 1 : quotient;
  }
};

}  // namespace foreign_storage