DateDaysEncoder.h

/*
 * Copyright 2019 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.
 */

#ifndef DATE_DAYS_ENCODER_H
#define DATE_DAYS_ENCODER_H

#include "Logger/Logger.h"

#include <iostream>
#include <memory>
#include "AbstractBuffer.h"
#include "Encoder.h"
#include "Shared/InlineNullValues.h"

#include <IR/DatumFetchers.h>

#include <tbb/parallel_for.h>
#include <tbb/parallel_reduce.h>

template <typename T, typename V>
class DateDaysEncoder : public Encoder {
 public:
  DateDaysEncoder(Data_Namespace::AbstractBuffer* buffer) : Encoder(buffer) {
    resetChunkStats();
  }

  std::shared_ptr<ChunkMetadata> getMetadata() override {
    auto res = Encoder::getMetadata();
    res->fillChunkStats(dataMin, dataMax, has_nulls);
    return res;
  }

  // Only called from the executor for synthesized meta-information.
  std::shared_ptr<ChunkMetadata> getMetadata(const hdk::ir::Type* type) override {
    auto chunk_metadata = std::make_shared<ChunkMetadata>(type, 0, 0, ChunkStats{});
    chunk_metadata->fillChunkStats(dataMin, dataMax, has_nulls);
    return chunk_metadata;
  }

  // Only called from the executor for synthesized meta-information.
  void updateStats(const int64_t val, const bool is_null) override {
    if (is_null) {
      has_nulls = true;
    } else {
      const auto data = static_cast<T>(val);
      dataMin = std::min(dataMin, data);
      dataMax = std::max(dataMax, data);
    }
  }

  // Only called from the executor for synthesized meta-information.
  void updateStats(const double val, const bool is_null) override {
    if (is_null) {
      has_nulls = true;
    } else {
      const auto data = static_cast<T>(val);
      dataMin = std::min(dataMin, data);
      dataMax = std::max(dataMax, data);
    }
  }

  void updateStats(const int8_t* const src_data, const size_t num_elements) override {
    const T* unencoded_data = reinterpret_cast<const T*>(src_data);
    for (size_t i = 0; i < num_elements; ++i) {
      encodeDataAndUpdateStats(unencoded_data[i]);
    }
  }

  void updateStats(const std::vector<std::string>* const src_data,
                   const size_t start_idx,
                   const size_t num_elements) override {
    UNREACHABLE();
  }

  void updateStats(const std::vector<ArrayDatum>* const src_data,
                   const size_t start_idx,
                   const size_t num_elements) override {
    UNREACHABLE();
  }

  void updateStatsEncoded(const int8_t* const dst_data,
                          const size_t num_elements,
                          bool fixlen_array = false) override {
    const V* data = reinterpret_cast<const V*>(dst_data);

    std::tie(dataMin, dataMax, has_nulls) = tbb::parallel_reduce(
        tbb::blocked_range(size_t(0), num_elements),
        std::tuple(dataMin, dataMax, has_nulls),
        [&](const auto& range, auto init) {
          auto [min, max, nulls] = init;
          for (size_t i = range.begin(); i < range.end(); i++) {
            if (data[i] != inline_null_value<V>()) {
              if (!fixlen_array || data[i] != inline_null_array_value<V>()) {
                const T val = DateConverters::get_epoch_seconds_from_days(data[i]);
                min = std::min(min, val);
                max = std::max(max, val);
              }
            } else {
              nulls = true;
            }
          }
          return std::tuple(min, max, nulls);
        },
        [&](auto lhs, auto rhs) {
          const auto [lhs_min, lhs_max, lhs_nulls] = lhs;
          const auto [rhs_min, rhs_max, rhs_nulls] = rhs;
          return std::tuple(std::min(lhs_min, rhs_min),
                            std::max(lhs_max, rhs_max),
                            lhs_nulls || rhs_nulls);
        });
  }

  // Only called from the executor for synthesized meta-information.
  void reduceStats(const Encoder& that) override {
    const auto that_typed = static_cast<const DateDaysEncoder<T, V>&>(that);
    if (that_typed.has_nulls) {
      has_nulls = true;
    }
    dataMin = std::min(dataMin, that_typed.dataMin);
    dataMax = std::max(dataMax, that_typed.dataMax);
  }

  void copyMetadata(const Encoder* copyFromEncoder) override {
    num_elems_ = copyFromEncoder->getNumElems();
    auto castedEncoder = reinterpret_cast<const DateDaysEncoder<T, V>*>(copyFromEncoder);
    dataMin = castedEncoder->dataMin;
    dataMax = castedEncoder->dataMax;
    has_nulls = castedEncoder->has_nulls;
  }

  void writeMetadata(FILE* f) override {
    // assumes pointer is already in right place
    fwrite((int8_t*)&num_elems_, sizeof(size_t), 1, f);
    fwrite((int8_t*)&dataMin, sizeof(T), 1, f);
    fwrite((int8_t*)&dataMax, sizeof(T), 1, f);
    fwrite((int8_t*)&has_nulls, sizeof(bool), 1, f);
  }

  void readMetadata(FILE* f) override {
    // assumes pointer is already in right place
    fread((int8_t*)&num_elems_, sizeof(size_t), 1, f);
    fread((int8_t*)&dataMin, 1, sizeof(T), f);
    fread((int8_t*)&dataMax, 1, sizeof(T), f);
    fread((int8_t*)&has_nulls, 1, sizeof(bool), f);
  }

  bool resetChunkStats(const ChunkStats& stats) override {
    const auto new_min = DatumFetcher::getDatumVal<T>(stats.min);
    const auto new_max = DatumFetcher::getDatumVal<T>(stats.max);

    if (dataMin == new_min && dataMax == new_max && has_nulls == stats.has_nulls) {
      return false;
    }

    dataMin = new_min;
    dataMax = new_max;
    has_nulls = stats.has_nulls;
    return true;
  }

  void resetChunkStats() override {
    dataMin = std::numeric_limits<T>::max();
    dataMax = std::numeric_limits<T>::lowest();
    has_nulls = false;
  }

  void fillChunkStats(ChunkStats& stats, const hdk::ir::Type* type) override {
    ::fillChunkStats(stats, type, dataMin, dataMax, has_nulls);
  }

  T dataMin;
  T dataMax;
  bool has_nulls;

 private:
  V encodeDataAndUpdateStats(const T& unencoded_data) {
    V encoded_data;
    if (unencoded_data == std::numeric_limits<V>::min()) {
      has_nulls = true;
      encoded_data = static_cast<V>(unencoded_data);
    } else {
      date_days_overflow_validator_.validate(unencoded_data);
      encoded_data = DateConverters::get_epoch_days_from_seconds(unencoded_data);
      const T data = DateConverters::get_epoch_seconds_from_days(encoded_data);
      dataMax = std::max(dataMax, data);
      dataMin = std::min(dataMin, data);
    }
    return encoded_data;
  }
};  // DateDaysEncoder

#endif  // DATE_DAYS_ENCODER_H