mirror of https://gitee.com/bigwinds/arangodb
387 lines
14 KiB
C++
387 lines
14 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// @brief skiplist index
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///
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/// @file
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///
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/// DISCLAIMER
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///
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/// Copyright 2014 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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/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
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/// @author Copyright 2011-2013, triAGENS GmbH, Cologne, Germany
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGODB_INDEXES_SKIPLIST_INDEX_H
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#define ARANGODB_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 "IndexOperators/index-operator.h"
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#include "VocBase/shaped-json.h"
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#include "VocBase/vocbase.h"
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#include "VocBase/voc-types.h"
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struct TRI_json_t;
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typedef struct {
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TRI_shaped_json_t* _fields; // list of shaped json objects which the
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// collection should know about
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size_t _numFields; // Note that the number of fields coming from
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// a query can be smaller than the number of
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// fields indexed
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}
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TRI_skiplist_index_key_t;
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namespace triagens {
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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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namespace arango {
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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 {
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private:
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friend class SkiplistIndex;
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// -----------------------------------------------------------------------------
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// --SECTION-- private structs
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// -----------------------------------------------------------------------------
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private:
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// Shorthand for the skiplist node
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typedef triagens::basics::SkipListNode<TRI_skiplist_index_key_t, TRI_index_element_t> Node;
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struct SkiplistIteratorInterval {
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Node* _leftEndPoint;
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Node* _rightEndPoint;
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SkiplistIteratorInterval ()
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: _leftEndPoint(nullptr),
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_rightEndPoint(nullptr) {
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}
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};
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// -----------------------------------------------------------------------------
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// --SECTION-- private variables
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// -----------------------------------------------------------------------------
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private:
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SkiplistIndex const* _index;
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size_t _currentInterval; // starts with 0, current interval used
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bool _reverse;
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Node* _cursor;
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std::vector<SkiplistIteratorInterval> _intervals;
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// -----------------------------------------------------------------------------
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// --SECTION-- constructors / destructors
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// -----------------------------------------------------------------------------
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public:
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SkiplistIterator (SkiplistIndex const* idx,
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bool reverse)
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: _index(idx),
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_currentInterval(0),
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_reverse(reverse),
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_cursor(nullptr) {
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}
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~SkiplistIterator () {
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}
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// always holds the last node returned, initially equal to
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// the _leftEndPoint of the first interval (or the
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// _rightEndPoint of the last interval in the reverse
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// case), can be nullptr if there are no intervals
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// (yet), or, in the reverse case, if the cursor is
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// at the end of the last interval. Additionally
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// in the non-reverse case _cursor is set to nullptr
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// if the cursor is exhausted.
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// See SkiplistNextIterationCallback and
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// SkiplistPrevIterationCallback for the exact
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// condition for the iterator to be exhausted.
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// -----------------------------------------------------------------------------
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// --SECTION-- public methods
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// -----------------------------------------------------------------------------
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public:
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size_t size () const;
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bool hasNext () const;
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TRI_index_element_t* next ();
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void initCursor ();
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void findHelper (
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TRI_index_operator_t const* indexOperator,
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std::vector<SkiplistIteratorInterval>& interval
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);
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// -----------------------------------------------------------------------------
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// --SECTION-- private methods
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// -----------------------------------------------------------------------------
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private:
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bool hasPrevIteration () const;
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TRI_index_element_t* prevIteration ();
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bool hasNextIteration () const;
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TRI_index_element_t* nextIteration ();
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bool findHelperIntervalIntersectionValid (
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SkiplistIteratorInterval const& lInterval,
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SkiplistIteratorInterval const& rInterval,
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SkiplistIteratorInterval& interval
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);
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bool findHelperIntervalValid (SkiplistIteratorInterval const& interval);
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};
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class SkiplistIndexIterator final : public IndexIterator {
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public:
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SkiplistIndexIterator (SkiplistIndex const* index,
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std::vector<TRI_index_operator_t*> op,
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bool reverse)
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: _index(index),
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_operators(op),
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_reverse(reverse),
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_currentOperator(0),
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_iterator(nullptr) {
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}
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~SkiplistIndexIterator () {
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for (auto& op : _operators) {
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delete op;
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}
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delete _iterator;
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}
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TRI_doc_mptr_t* next () override;
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void reset () override;
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private:
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SkiplistIndex const* _index;
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std::vector<TRI_index_operator_t*> _operators;
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bool _reverse;
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size_t _currentOperator;
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SkiplistIterator* _iterator;
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};
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// -----------------------------------------------------------------------------
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// --SECTION-- class SkiplistIndex
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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() (TRI_skiplist_index_key_t const* leftKey,
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TRI_index_element_t const* rightElement) const;
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explicit KeyElementComparator (SkiplistIndex* idx) {
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_idx = idx;
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}
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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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triagens::basics::SkipListCmpType cmptype) const;
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explicit ElementElementComparator (SkiplistIndex* idx) {
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_idx = idx;
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}
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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 triagens::basics::SkipList<TRI_skiplist_index_key_t, TRI_index_element_t> TRI_Skiplist;
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// -----------------------------------------------------------------------------
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// --SECTION-- constructors / destructors
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// -----------------------------------------------------------------------------
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public:
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SkiplistIndex () = delete;
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SkiplistIndex (TRI_idx_iid_t,
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struct TRI_document_collection_t*,
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std::vector<std::vector<triagens::basics::AttributeName>> const&,
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bool,
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bool);
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explicit SkiplistIndex (struct TRI_json_t const*);
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~SkiplistIndex ();
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// -----------------------------------------------------------------------------
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// --SECTION-- public methods
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// -----------------------------------------------------------------------------
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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 isSorted () const override final {
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return true;
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}
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bool hasSelectivityEstimate () const override final {
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return false;
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}
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size_t memory () const override final;
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triagens::basics::Json toJson (TRI_memory_zone_t*, bool) const override final;
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triagens::basics::Json toJsonFigures (TRI_memory_zone_t*) const override final;
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int insert (struct TRI_doc_mptr_t const*, bool) override final;
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int remove (struct TRI_doc_mptr_t const*, bool) 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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/// Note: this function will not destroy the passed slOperator before it returns
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/// Warning: who ever calls this function is responsible for destroying
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/// the TRI_index_operator_t* and the TRI_skiplist_iterator_t* results
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////////////////////////////////////////////////////////////////////////////////
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SkiplistIterator* lookup (TRI_index_operator_t*, bool) const;
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bool supportsFilterCondition (triagens::aql::AstNode const*,
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triagens::aql::Variable const*,
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size_t,
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size_t&,
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double&) const override;
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bool supportsSortCondition (triagens::aql::SortCondition const*,
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triagens::aql::Variable const*,
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size_t,
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double&) const override;
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IndexIterator* iteratorForCondition (IndexIteratorContext*,
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triagens::aql::Ast*,
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triagens::aql::AstNode const*,
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triagens::aql::Variable const*,
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bool) const override;
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triagens::aql::AstNode* specializeCondition (triagens::aql::AstNode*,
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triagens::aql::Variable const*) const override;
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// -----------------------------------------------------------------------------
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// --SECTION-- private methods
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// -----------------------------------------------------------------------------
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private:
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bool isDuplicateOperator (triagens::aql::AstNode const*,
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std::unordered_set<int> const&) const;
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int _CmpElmElm (TRI_index_element_t const* leftElement,
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TRI_index_element_t const* rightElement,
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triagens::basics::SkipListCmpType cmptype);
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int _CmpKeyElm (TRI_skiplist_index_key_t const* leftKey,
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TRI_index_element_t const* rightElement);
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bool accessFitsIndex (triagens::aql::AstNode const*,
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triagens::aql::AstNode const*,
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triagens::aql::AstNode const*,
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triagens::aql::Variable const*,
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std::unordered_map<size_t, std::vector<triagens::aql::AstNode const*>>&,
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bool) const;
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void matchAttributes (triagens::aql::AstNode const*,
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triagens::aql::Variable const*,
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std::unordered_map<size_t, std::vector<triagens::aql::AstNode const*>>&,
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size_t&,
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bool) const;
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// -----------------------------------------------------------------------------
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// --SECTION-- private variables
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// -----------------------------------------------------------------------------
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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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}
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#endif
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// -----------------------------------------------------------------------------
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// --SECTION-- END-OF-FILE
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// -----------------------------------------------------------------------------
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// Local Variables:
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// mode: outline-minor
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// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
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// End:
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