mirror of https://gitee.com/bigwinds/arangodb
468 lines
15 KiB
C++
468 lines
15 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Dr. Frank Celler
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_INDEXES_SKIPLIST_INDEX_H
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#define ARANGOD_INDEXES_SKIPLIST_INDEX_H 1
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#include "Basics/Common.h"
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#include "Aql/AstNode.h"
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#include "Basics/SkipList.h"
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#include "Indexes/IndexIterator.h"
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#include "Indexes/PathBasedIndex.h"
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#include "Utils/Transaction.h"
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#include "VocBase/vocbase.h"
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#include "VocBase/voc-types.h"
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#include <list>
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namespace arangodb {
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namespace aql {
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class SortCondition;
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struct Variable;
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}
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class SkiplistIndex;
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class Transaction;
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/// @brief Abstract Builder for lookup values in skiplist index
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class BaseSkiplistLookupBuilder {
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protected:
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bool _isEquality;
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bool _includeLower;
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bool _includeUpper;
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TransactionBuilderLeaser _lowerBuilder;
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arangodb::velocypack::Slice _lowerSlice;
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TransactionBuilderLeaser _upperBuilder;
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arangodb::velocypack::Slice _upperSlice;
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public:
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explicit BaseSkiplistLookupBuilder(Transaction* trx) :
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_lowerBuilder(trx), _upperBuilder(trx)
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{
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_isEquality = true;
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_includeUpper = true;
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_includeLower = true;
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_lowerBuilder->clear();
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_upperBuilder->clear();
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}
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virtual ~BaseSkiplistLookupBuilder() {};
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/// @brief Compute the next lookup values
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/// If returns false there is no further lookup
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virtual bool next() = 0;
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/// @brief Returns if we only have equality checks (== or IN)
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bool isEquality() const;
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/// @brief Get the lookup value for the lower bound.
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arangodb::velocypack::Slice const* getLowerLookup() const;
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/// @brief Test if the lower bound should be included.
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/// If there is no lower bound given returns true
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/// as well.
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bool includeLower() const;
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/// @brief Get the lookup value for the upper bound.
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arangodb::velocypack::Slice const* getUpperLookup() const;
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/// @brief Test if the upper bound should be included.
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/// If there is no upper bound given returns true
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/// as well.
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bool includeUpper() const;
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};
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/// @brief Builder for lookup values in skiplist index
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/// Offers lower and upper bound lookup values
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/// and handles multiplication of IN search values.
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/// Also makes sure that the lookup values are
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/// returned in the correct ordering. And no
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/// lookup is returned twice.
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class SkiplistLookupBuilder : public BaseSkiplistLookupBuilder {
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public:
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SkiplistLookupBuilder(
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Transaction* trx,
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std::vector<std::vector<arangodb::aql::AstNode const*>>&,
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arangodb::aql::Variable const*, bool);
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~SkiplistLookupBuilder() {}
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/// @brief Compute the next lookup values
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/// If returns false there is no further lookup
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bool next() override;
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};
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class SkiplistInLookupBuilder : public BaseSkiplistLookupBuilder {
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private:
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struct PosStruct {
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size_t field;
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size_t current;
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size_t _max; // thanks, windows.h!
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PosStruct(size_t f, size_t c, size_t m) : field(f), current(c), _max(m) {}
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};
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TransactionBuilderLeaser _dataBuilder;
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/// @brief keeps track of the positions in the in-lookup
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/// values. (field, inPosition, maxPosition)
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std::list<PosStruct> _inPositions;
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bool _done;
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public:
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SkiplistInLookupBuilder(
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Transaction* trx,
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std::vector<std::vector<arangodb::aql::AstNode const*>>&,
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arangodb::aql::Variable const*, bool);
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~SkiplistInLookupBuilder() {}
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/// @brief Compute the next lookup values
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/// If returns false there is no further lookup
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bool next() override;
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private:
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bool forwardInPosition();
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void buildSearchValues();
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Iterator structure for skip list. We require a start and stop node
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///
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/// Intervals are open in the sense that both end points are not members
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/// of the interval. This means that one has to use SkipList::nextNode
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/// on the start node to get the first element and that the stop node
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/// can be NULL. Note that it is ensured that all intervals in an iterator
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/// are non-empty.
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////////////////////////////////////////////////////////////////////////////////
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class SkiplistIterator final : public IndexIterator {
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private:
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friend class SkiplistIndex;
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private:
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// Shorthand for the skiplist node
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typedef arangodb::basics::SkipListNode<VPackSlice,
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TRI_index_element_t> Node;
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private:
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bool _reverse;
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Node* _cursor;
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Node* _leftEndPoint; // Interval left border, first excluded element
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Node* _rightEndPoint; // Interval right border, first excluded element
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public:
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SkiplistIterator(bool reverse, Node* left,
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Node* right)
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: _reverse(reverse),
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_leftEndPoint(left),
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_rightEndPoint(right) {
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reset(); // Initializes the cursor
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}
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// always holds the last node returned, initially equal to
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// the _leftEndPoint (or the
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// _rightEndPoint in the reverse case),
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// can be nullptr if the iterator is exhausted.
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public:
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Get the next element in the skiplist
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////////////////////////////////////////////////////////////////////////////////
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TRI_doc_mptr_t* next() override;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Reset the cursor
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////////////////////////////////////////////////////////////////////////////////
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void reset() override;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Iterator structure for skip list. We require a start and stop node
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///
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/// Intervals are open in the sense that both end points are not members
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/// of the interval. This means that one has to use SkipList::nextNode
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/// on the start node to get the first element and that the stop node
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/// can be NULL. Note that it is ensured that all intervals in an iterator
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/// are non-empty.
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////////////////////////////////////////////////////////////////////////////////
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class SkiplistIterator2 final : public IndexIterator {
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private:
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// Shorthand for the skiplist node
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typedef arangodb::basics::SkipListNode<VPackSlice,
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TRI_index_element_t> Node;
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typedef arangodb::basics::SkipList<VPackSlice,
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TRI_index_element_t> TRI_Skiplist;
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private:
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TRI_Skiplist const* _skiplistIndex;
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bool _reverse;
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Node* _cursor;
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// The pair.first is the left border
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// The pair.second is the right border
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// Both borders are inclusive
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std::vector<std::pair<Node*, Node*>> _intervals;
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size_t _currentInterval;
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BaseSkiplistLookupBuilder* _builder;
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std::function<int(TRI_index_element_t const*, TRI_index_element_t const*,
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arangodb::basics::SkipListCmpType)> _CmpElmElm;
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public:
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SkiplistIterator2(
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TRI_Skiplist const* skiplist,
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std::function<int(TRI_index_element_t const*, TRI_index_element_t const*,
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arangodb::basics::SkipListCmpType)> const& CmpElmElm,
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bool reverse, BaseSkiplistLookupBuilder* builder)
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: _skiplistIndex(skiplist),
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_reverse(reverse),
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_cursor(nullptr),
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_currentInterval(0),
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_builder(builder),
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_CmpElmElm(CmpElmElm) {
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TRI_ASSERT(_builder != nullptr);
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initNextInterval(); // Initializes the cursor
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TRI_ASSERT((_intervals.empty() && _cursor == nullptr) ||
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(!_intervals.empty() && _cursor != nullptr));
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}
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~SkiplistIterator2() {
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delete _builder;
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}
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// always holds the last node returned, initially equal to
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// the _leftEndPoint (or the
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// _rightEndPoint in the reverse case),
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// can be nullptr if the iterator is exhausted.
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public:
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Get the next element in the skiplist
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////////////////////////////////////////////////////////////////////////////////
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TRI_doc_mptr_t* next() override;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Reset the cursor
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////////////////////////////////////////////////////////////////////////////////
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void reset() override;
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private:
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Initialize left and right endpoints with current lookup
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/// value. Also points the _cursor to the border of this interval.
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////////////////////////////////////////////////////////////////////////////////
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void initNextInterval();
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Forward the cursor to the next interval. If there was no
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/// interval the next one is computed. If the _cursor has
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/// nullptr after this call the iterator is exhausted.
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////////////////////////////////////////////////////////////////////////////////
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void forwardCursor();
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Checks if the interval is valid. It is declared invalid if
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/// one border is nullptr or the right is lower than left.
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////////////////////////////////////////////////////////////////////////////////
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bool intervalValid(Node*, Node*) const;
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};
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class SkiplistIndex final : public PathBasedIndex {
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struct KeyElementComparator {
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int operator()(VPackSlice const* leftKey,
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TRI_index_element_t const* rightElement) const;
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explicit KeyElementComparator(SkiplistIndex* idx) { _idx = idx; }
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private:
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SkiplistIndex* _idx;
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};
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struct ElementElementComparator {
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int operator()(TRI_index_element_t const* leftElement,
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TRI_index_element_t const* rightElement,
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arangodb::basics::SkipListCmpType cmptype) const;
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explicit ElementElementComparator(SkiplistIndex* idx) { _idx = idx; }
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private:
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SkiplistIndex* _idx;
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};
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friend class SkiplistIterator;
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friend struct KeyElementComparator;
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friend struct ElementElementComparator;
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typedef arangodb::basics::SkipList<VPackSlice,
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TRI_index_element_t> TRI_Skiplist;
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public:
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SkiplistIndex() = delete;
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SkiplistIndex(TRI_idx_iid_t, LogicalCollection*,
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arangodb::velocypack::Slice const&);
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SkiplistIndex(
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TRI_idx_iid_t, arangodb::LogicalCollection*,
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std::vector<std::vector<arangodb::basics::AttributeName>> const&, bool,
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bool);
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explicit SkiplistIndex(VPackSlice const&);
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~SkiplistIndex();
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public:
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IndexType type() const override final {
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return Index::TRI_IDX_TYPE_SKIPLIST_INDEX;
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}
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bool allowExpansion() const override final { return true; }
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bool canBeDropped() const override final { return true; }
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bool isSorted() const override final { return true; }
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bool hasSelectivityEstimate() const override final { return false; }
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size_t memory() const override final;
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void toVelocyPack(VPackBuilder&, bool) const override final;
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void toVelocyPackFigures(VPackBuilder&) const override final;
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int insert(arangodb::Transaction*, struct TRI_doc_mptr_t const*,
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bool) override final;
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int remove(arangodb::Transaction*, struct TRI_doc_mptr_t const*,
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bool) override final;
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int unload() override final;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief attempts to locate an entry in the skip list index
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///
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/// Warning: who ever calls this function is responsible for destroying
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/// the velocypack::Slice and the SkiplistIterator* results
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//////////////////////////////////////////////////////////////////////////////
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SkiplistIterator* lookup(arangodb::Transaction*, arangodb::velocypack::Slice const,
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bool) const;
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bool supportsFilterCondition(arangodb::aql::AstNode const*,
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arangodb::aql::Variable const*, size_t, size_t&,
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double&) const override;
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bool supportsSortCondition(arangodb::aql::SortCondition const*,
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arangodb::aql::Variable const*, size_t,
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double&, size_t&) const override;
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IndexIterator* iteratorForCondition(arangodb::Transaction*,
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IndexIteratorContext*,
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arangodb::aql::AstNode const*,
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arangodb::aql::Variable const*,
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bool) const override;
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arangodb::aql::AstNode* specializeCondition(
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arangodb::aql::AstNode*, arangodb::aql::Variable const*) const override;
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private:
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bool isDuplicateOperator(arangodb::aql::AstNode const*,
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std::unordered_set<int> const&) const;
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bool accessFitsIndex(
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arangodb::aql::AstNode const*, arangodb::aql::AstNode const*,
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arangodb::aql::AstNode const*, arangodb::aql::Variable const*,
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std::unordered_map<size_t, std::vector<arangodb::aql::AstNode const*>>&,
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bool) const;
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bool accessFitsIndex(
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arangodb::aql::AstNode const*, arangodb::aql::AstNode const*,
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arangodb::aql::AstNode const*, arangodb::aql::Variable const*,
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std::vector<std::vector<arangodb::aql::AstNode const*>>&) const;
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void matchAttributes(
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arangodb::aql::AstNode const*, arangodb::aql::Variable const*,
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std::unordered_map<size_t, std::vector<arangodb::aql::AstNode const*>>&,
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size_t&, bool) const;
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bool findMatchingConditions(
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arangodb::aql::AstNode const*, arangodb::aql::Variable const*,
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std::vector<std::vector<arangodb::aql::AstNode const*>>&, bool&) const;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Checks if the interval is valid. It is declared invalid if
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/// one border is nullptr or the right is lower than left.
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////////////////////////////////////////////////////////////////////////////////
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// Shorthand for the skiplist node
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typedef arangodb::basics::SkipListNode<VPackSlice,
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TRI_index_element_t> Node;
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bool intervalValid(Node* left, Node* right) const;
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private:
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ElementElementComparator CmpElmElm;
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KeyElementComparator CmpKeyElm;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief the actual skiplist index
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//////////////////////////////////////////////////////////////////////////////
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TRI_Skiplist* _skiplistIndex;
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};
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}
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#endif
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