ColumnFetcher.h

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/*
 * Copyright 2022 HEAVY.AI, 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 "DataMgr/Allocators/DeviceAllocator.h"
#include "QueryEngine/ColumnarResults.h"
#include "QueryEngine/Descriptors/QueryFragmentDescriptor.h"
#include "QueryEngine/JoinHashTable/Runtime/HashJoinRuntime.h"

namespace std {
template <>
struct hash<std::vector<int>> {
  size_t operator()(const std::vector<int>& vec) const {
    return vec.size() ^ boost::hash_range(vec.begin(), vec.end());
  }
};

template <>
struct hash<std::pair<int, int>> {
  size_t operator()(const std::pair<int, int>& p) const {
    return boost::hash<std::pair<int, int>>()(p);
  }
};

}  // namespace std

struct FetchResult {
  std::vector<std::vector<const int8_t*>> col_buffers;
  std::vector<std::vector<int64_t>> num_rows;
  std::vector<std::vector<uint64_t>> frag_offsets;
};

using MergedChunk = std::pair<AbstractBuffer*, AbstractBuffer*>;

class ColumnFetcher {
 public:
  ColumnFetcher(Executor* executor, ColumnCacheMap& column_cache);

  static std::pair<const int8_t*, size_t> getOneColumnFragment(
      Executor* executor,
      const Analyzer::ColumnVar& hash_col,
      const Fragmenter_Namespace::FragmentInfo& fragment,
      const Data_Namespace::MemoryLevel effective_mem_lvl,
      const int device_id,
      DeviceAllocator* device_allocator,
      const size_t thread_idx,
      std::vector<std::shared_ptr<Chunk_NS::Chunk>>& chunks_owner,
      ColumnCacheMap& column_cache);

  static JoinColumn makeJoinColumn(
      Executor* executor,
      const Analyzer::ColumnVar& hash_col,
      const std::vector<Fragmenter_Namespace::FragmentInfo>& fragments,
      const Data_Namespace::MemoryLevel effective_mem_lvl,
      const int device_id,
      DeviceAllocator* device_allocator,
      const size_t thread_idx,
      std::vector<std::shared_ptr<Chunk_NS::Chunk>>& chunks_owner,
      std::vector<std::shared_ptr<void>>& malloc_owner,
      ColumnCacheMap& column_cache);

  const int8_t* getOneTableColumnFragment(
      const shared::TableKey& table_key,
      const int frag_id,
      const int col_id,
      const std::map<shared::TableKey, const TableFragments*>& all_tables_fragments,
      std::list<std::shared_ptr<Chunk_NS::Chunk>>& chunk_holder,
      std::list<ChunkIter>& chunk_iter_holder,
      const Data_Namespace::MemoryLevel memory_level,
      const int device_id,
      DeviceAllocator* device_allocator) const;

  const int8_t* getAllTableColumnFragments(
      const shared::TableKey& table_key,
      const int col_id,
      const std::map<shared::TableKey, const TableFragments*>& all_tables_fragments,
      const Data_Namespace::MemoryLevel memory_level,
      const int device_id,
      DeviceAllocator* device_allocator,
      const size_t thread_idx) const;

  const int8_t* getResultSetColumn(const InputColDescriptor* col_desc,
                                   const Data_Namespace::MemoryLevel memory_level,
                                   const int device_id,
                                   DeviceAllocator* device_allocator,
                                   const size_t thread_idx) const;

  const int8_t* linearizeColumnFragments(
      const shared::TableKey& table_key,
      const int col_id,
      const std::map<shared::TableKey, const TableFragments*>& all_tables_fragments,
      std::list<std::shared_ptr<Chunk_NS::Chunk>>& chunk_holder,
      std::list<ChunkIter>& chunk_iter_holder,
      const Data_Namespace::MemoryLevel memory_level,
      const int device_id,
      DeviceAllocator* device_allocator,
      const size_t thread_idx) const;

  void freeTemporaryCpuLinearizedIdxBuf();
  void freeLinearizedBuf();

 private:
  static const int8_t* transferColumnIfNeeded(
      const ColumnarResults* columnar_results,
      const int col_id,
      Data_Namespace::DataMgr* data_mgr,
      const Data_Namespace::MemoryLevel memory_level,
      const int device_id,
      DeviceAllocator* device_allocator);

  MergedChunk linearizeVarLenArrayColFrags(
      int32_t db_id,
      std::list<std::shared_ptr<Chunk_NS::Chunk>>& chunk_holder,
      std::list<ChunkIter>& chunk_iter_holder,
      std::list<std::shared_ptr<Chunk_NS::Chunk>>& local_chunk_holder,
      std::list<ChunkIter>& local_chunk_iter_holder,
      std::list<size_t>& local_chunk_num_tuples,
      MemoryLevel memory_level,
      const ColumnDescriptor* cd,
      const int device_id,
      const size_t total_data_buf_size,
      const size_t total_idx_buf_size,
      const size_t total_num_tuples,
      DeviceAllocator* device_allocator,
      const size_t thread_idx) const;

  MergedChunk linearizeFixedLenArrayColFrags(
      int32_t db_id,
      std::list<std::shared_ptr<Chunk_NS::Chunk>>& chunk_holder,
      std::list<ChunkIter>& chunk_iter_holder,
      std::list<std::shared_ptr<Chunk_NS::Chunk>>& local_chunk_holder,
      std::list<ChunkIter>& local_chunk_iter_holder,
      std::list<size_t>& local_chunk_num_tuples,
      MemoryLevel memory_level,
      const ColumnDescriptor* cd,
      const int device_id,
      const size_t total_data_buf_size,
      const size_t total_idx_buf_size,
      const size_t total_num_tuples,
      DeviceAllocator* device_allocator,
      const size_t thread_idx) const;

  void addMergedChunkIter(const InputColDescriptor col_desc,
                          const int device_id,
                          int8_t* chunk_iter_ptr) const;

  const int8_t* getChunkiter(const InputColDescriptor col_desc,
                             const int device_id = 0) const;

  ChunkIter prepareChunkIter(AbstractBuffer* merged_data_buf,
                             AbstractBuffer* merged_index_buf,
                             ChunkIter& chunk_iter,
                             bool is_true_varlen_type,
                             const size_t total_num_tuples) const;

  const int8_t* getResultSetColumn(const ResultSetPtr& buffer,
                                   const shared::TableKey& table_key,
                                   const int col_id,
                                   const Data_Namespace::MemoryLevel memory_level,
                                   const int device_id,
                                   DeviceAllocator* device_allocator,
                                   const size_t thread_idx) const;

  Executor* executor_;
  mutable std::mutex columnar_fetch_mutex_;
  mutable std::mutex varlen_chunk_fetch_mutex_;
  mutable std::mutex linearization_mutex_;
  mutable std::mutex chunk_list_mutex_;
  mutable std::mutex linearized_col_cache_mutex_;
  ColumnCacheMap& columnarized_table_cache_;
  mutable std::unordered_map<InputColDescriptor, std::unique_ptr<const ColumnarResults>>
      columnarized_scan_table_cache_;
  using DeviceMergedChunkIterMap = std::unordered_map<int, int8_t*>;
  using DeviceMergedChunkMap = std::unordered_map<int, AbstractBuffer*>;
  mutable std::unordered_map<InputColDescriptor, DeviceMergedChunkIterMap>
      linearized_multi_frag_chunk_iter_cache_;
  mutable std::unordered_map<int, AbstractBuffer*>
      linearlized_temporary_cpu_index_buf_cache_;
  mutable std::unordered_map<InputColDescriptor, DeviceMergedChunkMap>
      linearized_data_buf_cache_;
  mutable std::unordered_map<InputColDescriptor, DeviceMergedChunkMap>
      linearized_idx_buf_cache_;

  friend class QueryCompilationDescriptor;
  friend class TableFunctionExecutionContext;  // TODO(adb)
};