arangodb/arangod/Indexes/RocksDBIndex.h

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGOD_INDEXES_ROCKSDB_INDEX_H
#define ARANGOD_INDEXES_ROCKSDB_INDEX_H 1

#include "Basics/Common.h"
#include "Aql/AstNode.h"
#include "Indexes/IndexIterator.h"
#include "Indexes/PathBasedIndex.h"
#include "Indexes/RocksDBFeature.h"
#include "VocBase/vocbase.h"
#include "VocBase/voc-types.h"

#include <rocksdb/db.h>
#include <rocksdb/utilities/optimistic_transaction_db.h>

#include <velocypack/Buffer.h>
#include <velocypack/Slice.h>

namespace rocksdb {
class OptimisticTransactionDB;
}

namespace arangodb {
namespace aql {
class SortCondition;
struct Variable;
}

class PrimaryIndex;
class RocksDBIndex;
class Transaction;

////////////////////////////////////////////////////////////////////////////////
/// @brief Iterator structure for RocksDB. We require a start and stop node
////////////////////////////////////////////////////////////////////////////////

class RocksDBIterator : public IndexIterator {
 private:
  friend class RocksDBIndex;

 private:
  arangodb::Transaction* _trx;
  arangodb::PrimaryIndex* _primaryIndex;
  rocksdb::OptimisticTransactionDB* _db;
  std::unique_ptr<rocksdb::Iterator> _cursor;
  std::unique_ptr<arangodb::velocypack::Buffer<char>> _leftEndpoint;   // Interval left border
  std::unique_ptr<arangodb::velocypack::Buffer<char>> _rightEndpoint;  // Interval right border
  bool const _reverse;
  bool _probe;

 public:
  RocksDBIterator(arangodb::Transaction* trx, 
                  arangodb::RocksDBIndex const* index,
                  arangodb::PrimaryIndex* primaryIndex,
                  rocksdb::OptimisticTransactionDB* db,
                  bool reverse, 
                  arangodb::velocypack::Slice const& left,
                  arangodb::velocypack::Slice const& right);

  ~RocksDBIterator() = default;

 public:

  ////////////////////////////////////////////////////////////////////////////////
  /// @brief Get the next element in the index
  ////////////////////////////////////////////////////////////////////////////////

  TRI_doc_mptr_t* next() override;

  ////////////////////////////////////////////////////////////////////////////////
  /// @brief Reset the cursor
  ////////////////////////////////////////////////////////////////////////////////

  void reset() override;
};

class RocksDBIndex final : public PathBasedIndex {
  friend class RocksDBIterator;

 public:
  RocksDBIndex() = delete;

  RocksDBIndex(
      TRI_idx_iid_t, struct TRI_document_collection_t*,
      std::vector<std::vector<arangodb::basics::AttributeName>> const&, bool,
      bool);

  explicit RocksDBIndex(VPackSlice const&);

  ~RocksDBIndex();

 public:
  IndexType type() const override final {
    return Index::TRI_IDX_TYPE_ROCKSDB_INDEX;
  }
  
  bool isPersistent() const override final { return true; }
  bool canBeDropped() const override final { return true; }

  bool isSorted() const override final { return true; }

  bool hasSelectivityEstimate() const override final { return false; }

  size_t memory() const override final;

  void toVelocyPack(VPackBuilder&, bool) const override final;
  void toVelocyPackFigures(VPackBuilder&) const override final;
  
  static constexpr size_t minimalPrefixSize() {
    return sizeof(TRI_voc_tick_t);
  }

  static constexpr size_t keyPrefixSize() {
    return sizeof(TRI_voc_tick_t) + sizeof(TRI_voc_cid_t) + sizeof(TRI_idx_iid_t);
  }
  
  static std::string buildPrefix(TRI_voc_tick_t databaseId) {
    std::string value;
    value.append(reinterpret_cast<char const*>(&databaseId), sizeof(TRI_voc_tick_t));
    return value;
  }
  
  static std::string buildPrefix(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId) {
    std::string value;
    value.append(reinterpret_cast<char const*>(&databaseId), sizeof(TRI_voc_tick_t));
    value.append(reinterpret_cast<char const*>(&collectionId), sizeof(TRI_voc_cid_t));
    return value;
  }

  static std::string buildPrefix(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId, TRI_idx_iid_t indexId) {
    std::string value;
    value.reserve(keyPrefixSize());
    value.append(reinterpret_cast<char const*>(&databaseId), sizeof(TRI_voc_tick_t));
    value.append(reinterpret_cast<char const*>(&collectionId), sizeof(TRI_voc_cid_t));
    value.append(reinterpret_cast<char const*>(&indexId), sizeof(TRI_idx_iid_t));
    return value;
  }

  int insert(arangodb::Transaction*, struct TRI_doc_mptr_t const*,
             bool) override final;

  int remove(arangodb::Transaction*, struct TRI_doc_mptr_t const*,
             bool) override final;

  int drop() override final;

  //////////////////////////////////////////////////////////////////////////////
  /// @brief attempts to locate an entry in the index
  ///
  /// Warning: who ever calls this function is responsible for destroying
  /// the velocypack::Slice and the RocksDBIterator* results
  //////////////////////////////////////////////////////////////////////////////

  RocksDBIterator* lookup(arangodb::Transaction*, arangodb::velocypack::Slice const,
                          bool) const;

  bool supportsFilterCondition(arangodb::aql::AstNode const*,
                               arangodb::aql::Variable const*, size_t, size_t&,
                               double&) const override;

  bool supportsSortCondition(arangodb::aql::SortCondition const*,
                             arangodb::aql::Variable const*, size_t,
                             double&, size_t&) const override;

  IndexIterator* iteratorForCondition(arangodb::Transaction*,
                                      IndexIteratorContext*,
                                      arangodb::aql::Ast*,
                                      arangodb::aql::AstNode const*,
                                      arangodb::aql::Variable const*,
                                      bool) const override;

  arangodb::aql::AstNode* specializeCondition(
      arangodb::aql::AstNode*, arangodb::aql::Variable const*) const override;

 private:
  bool isDuplicateOperator(arangodb::aql::AstNode const*,
                           std::unordered_set<int> const&) const;

  bool accessFitsIndex(
      arangodb::aql::AstNode const*, arangodb::aql::AstNode const*,
      arangodb::aql::AstNode const*, arangodb::aql::Variable const*,
      std::unordered_map<size_t, std::vector<arangodb::aql::AstNode const*>>&,
      bool) const;

  void matchAttributes(
      arangodb::aql::AstNode const*, arangodb::aql::Variable const*,
      std::unordered_map<size_t, std::vector<arangodb::aql::AstNode const*>>&,
      size_t&, bool) const;

 private:

  //////////////////////////////////////////////////////////////////////////////
  /// @brief the RocksDB instance
  //////////////////////////////////////////////////////////////////////////////

  rocksdb::OptimisticTransactionDB* _db;

};
}

#endif