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arangodb/arangod/Indexes/HashIndex.h

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////////////////////////////////////////////////////////////////////////////////
/// 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 Dr. Frank Celler
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_INDEXES_HASH_INDEX_H
#define ARANGOD_INDEXES_HASH_INDEX_H 1
#include "Basics/Common.h"
#include "Basics/AssocMulti.h"
#include "Basics/AssocUnique.h"
#include "Basics/VelocyPackHelper.h"
#include "Basics/fasthash.h"
#include "Indexes/PathBasedIndex.h"
#include "Indexes/IndexIterator.h"
#include "Utils/Transaction.h"
#include "VocBase/vocbase.h"
#include "VocBase/voc-types.h"
#include <velocypack/Iterator.h>
#include <velocypack/Slice.h>
#include <velocypack/velocypack-aliases.h>
/// @brief hash index query parameter
namespace arangodb {
class HashIndex;
/// @brief Class to build Slice lookups out of AST Conditions
class LookupBuilder {
private:
TransactionBuilderLeaser _builder;
bool _usesIn;
bool _isEmpty;
size_t _coveredFields;
std::unordered_map<size_t, arangodb::aql::AstNode const*> _mappingFieldCondition;
std::unordered_map<
size_t, std::pair<size_t, std::vector<arangodb::velocypack::Slice>>>
_inPosition;
TransactionBuilderLeaser _inStorage;
public:
LookupBuilder(
arangodb::Transaction*, arangodb::aql::AstNode const*,
arangodb::aql::Variable const*,
std::vector<std::vector<arangodb::basics::AttributeName>> const&);
arangodb::velocypack::Slice lookup();
bool hasAndGetNext();
void reset();
private:
bool incrementInPosition();
void buildNextSearchValue();
};
class HashIndexIterator final : public IndexIterator {
public:
/// @brief Construct an HashIndexIterator based on Ast Conditions
HashIndexIterator(LogicalCollection* collection, arangodb::Transaction* trx,
ManagedDocumentResult* mmdr,
HashIndex const* index,
arangodb::aql::AstNode const*,
arangodb::aql::Variable const*);
~HashIndexIterator() = default;
char const* typeName() const override { return "hash-index-iterator"; }
IndexLookupResult next() override;
void nextBabies(std::vector<IndexLookupResult>&, size_t) override;
void reset() override;
private:
HashIndex const* _index;
LookupBuilder _lookups;
std::vector<HashIndexElement*> _buffer;
size_t _posInBuffer;
};
class HashIndexIteratorVPack final : public IndexIterator {
public:
/// @brief Construct an HashIndexIterator based on VelocyPack
HashIndexIteratorVPack(LogicalCollection* collection,
arangodb::Transaction* trx,
ManagedDocumentResult* mmdr,
HashIndex const* index,
std::unique_ptr<arangodb::velocypack::Builder>& searchValues);
~HashIndexIteratorVPack();
char const* typeName() const override { return "hash-index-iterator-vpack"; }
IndexLookupResult next() override;
void reset() override;
private:
HashIndex const* _index;
std::unique_ptr<arangodb::velocypack::Builder> _searchValues;
arangodb::velocypack::ArrayIterator _iterator;
std::vector<HashIndexElement*> _buffer;
size_t _posInBuffer;
};
class HashIndex final : public PathBasedIndex {
friend class HashIndexIterator;
friend class HashIndexIteratorVPack;
public:
HashIndex() = delete;
HashIndex(TRI_idx_iid_t, LogicalCollection*,
arangodb::velocypack::Slice const&);
~HashIndex();
public:
IndexType type() const override {
return Index::TRI_IDX_TYPE_HASH_INDEX;
}
bool allowExpansion() const override { return true; }
bool canBeDropped() const override { return true; }
bool isSorted() const override { return false; }
bool hasSelectivityEstimate() const override { return true; }
double selectivityEstimate(arangodb::StringRef const* = nullptr) const override;
size_t memory() const override;
void toVelocyPack(VPackBuilder&, bool) const override;
void toVelocyPackFigures(VPackBuilder&) const override;
bool matchesDefinition(VPackSlice const& info) const override;
int insert(arangodb::Transaction*, TRI_voc_rid_t, arangodb::velocypack::Slice const&, bool isRollback) override;
int remove(arangodb::Transaction*, TRI_voc_rid_t, arangodb::velocypack::Slice const&, bool isRollback) override;
int batchInsert(arangodb::Transaction*, std::vector<std::pair<TRI_voc_rid_t, arangodb::velocypack::Slice>> const&, size_t) override;
int unload() override;
int sizeHint(arangodb::Transaction*, size_t) override;
bool hasBatchInsert() const override { return true; }
bool supportsFilterCondition(arangodb::aql::AstNode const*,
arangodb::aql::Variable const*, size_t, size_t&,
double&) const override;
IndexIterator* iteratorForCondition(arangodb::Transaction*,
ManagedDocumentResult*,
arangodb::aql::AstNode const*,
arangodb::aql::Variable const*,
bool) const override;
/// @brief creates an IndexIterator for the given VelocyPackSlices
/// Each slice represents the field at the same position. (order matters)
/// And each slice has to be an object of one of the following types:
/// 1) {"eq": <compareValue>} // The value in index is exactly this
/// 2) {"in": <compareValues>} // The value in index os one of them
IndexIterator* iteratorForSlice(arangodb::Transaction*,
ManagedDocumentResult*,
arangodb::velocypack::Slice const,
bool) const override;
arangodb::aql::AstNode* specializeCondition(
arangodb::aql::AstNode*, arangodb::aql::Variable const*) const override;
private:
/// @brief locates entries in the hash index given a velocypack slice
int lookup(arangodb::Transaction*, arangodb::velocypack::Slice,
std::vector<HashIndexElement*>&) const;
int insertUnique(arangodb::Transaction*, TRI_voc_rid_t, arangodb::velocypack::Slice const&, bool isRollback);
int batchInsertUnique(arangodb::Transaction*,
std::vector<std::pair<TRI_voc_rid_t, arangodb::velocypack::Slice>> const&, size_t);
int insertMulti(arangodb::Transaction*, TRI_voc_rid_t, arangodb::velocypack::Slice const&, bool isRollback);
int batchInsertMulti(arangodb::Transaction*,
std::vector<std::pair<TRI_voc_rid_t, arangodb::velocypack::Slice>> const&, size_t);
int removeUniqueElement(arangodb::Transaction*, HashIndexElement*, bool);
int removeMultiElement(arangodb::Transaction*, HashIndexElement*, bool);
bool accessFitsIndex(arangodb::aql::AstNode const* access,
arangodb::aql::AstNode const* other,
arangodb::aql::Variable const* reference,
std::unordered_set<size_t>& found) const;
/// @brief given an element generates a hash integer
private:
class HashElementFunc {
public:
HashElementFunc() {}
uint64_t operator()(void* userData, HashIndexElement const* element,
bool byKey = true) {
uint64_t hash = element->hash();
if (byKey) {
return hash;
}
TRI_voc_rid_t revisionId = element->revisionId();
return fasthash64_uint64(revisionId, hash);
}
};
/// @brief determines if a key corresponds to an element
class IsEqualElementElementByKey {
size_t _numFields;
bool _allowExpansion;
public:
IsEqualElementElementByKey(size_t n, bool allowExpansion) : _numFields(n), _allowExpansion(allowExpansion) {}
bool operator()(void* userData, HashIndexElement const* left,
HashIndexElement const* right) {
TRI_ASSERT(left->revisionId() != 0);
TRI_ASSERT(right->revisionId() != 0);
if (!_allowExpansion && left->revisionId() == right->revisionId()) {
return true;
}
IndexLookupContext* context = static_cast<IndexLookupContext*>(userData);
for (size_t i = 0; i < _numFields; ++i) {
VPackSlice leftData = left->slice(context, i);
VPackSlice rightData = right->slice(context, i);
int res = arangodb::basics::VelocyPackHelper::compare(leftData, rightData, false);
if (res != 0) {
return false;
}
}
return true;
}
};
private:
/// @brief the actual hash index (unique type)
typedef arangodb::basics::AssocUnique<arangodb::velocypack::Slice,
HashIndexElement*> TRI_HashArray_t;
struct UniqueArray {
UniqueArray() = delete;
UniqueArray(size_t numPaths, TRI_HashArray_t*, HashElementFunc*,
IsEqualElementElementByKey*);
~UniqueArray();
TRI_HashArray_t* _hashArray; // the hash array itself, unique values
HashElementFunc* _hashElement; // hash function for elements
IsEqualElementElementByKey* _isEqualElElByKey; // comparison func
size_t _numPaths;
};
/// @brief the actual hash index (multi type)
typedef arangodb::basics::AssocMulti<arangodb::velocypack::Slice,
HashIndexElement*, uint32_t,
false> TRI_HashArrayMulti_t;
struct MultiArray {
MultiArray() = delete;
MultiArray(size_t numPaths,
TRI_HashArrayMulti_t*, HashElementFunc*,
IsEqualElementElementByKey*);
~MultiArray();
TRI_HashArrayMulti_t*
_hashArray; // the hash array itself, non-unique values
HashElementFunc* _hashElement; // hash function for elements
IsEqualElementElementByKey* _isEqualElElByKey; // comparison func
size_t _numPaths;
};
union {
UniqueArray* _uniqueArray;
MultiArray* _multiArray;
};
};
}
#endif