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arangodb/arangod/Indexes/EdgeIndex.cpp

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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
////////////////////////////////////////////////////////////////////////////////
#include "EdgeIndex.h"
#include "Aql/AstNode.h"
#include "Aql/SortCondition.h"
#include "Basics/Exceptions.h"
#include "Basics/fasthash.h"
#include "Basics/hashes.h"
#include "Indexes/SimpleAttributeEqualityMatcher.h"
#include "Utils/CollectionNameResolver.h"
#include "VocBase/document-collection.h"
#include "VocBase/edge-collection.h"
#include "VocBase/transaction.h"
using namespace arangodb;
////////////////////////////////////////////////////////////////////////////////
/// @brief hashes an edge key
////////////////////////////////////////////////////////////////////////////////
static uint64_t HashElementKey(void*, VPackSlice const* key) {
// TODO: Can we unify all HashElementKey functions for VPack?
TRI_ASSERT(key != nullptr);
uint64_t hash = 0x87654321;
if (!key->isString()) {
// Illegal Edge entry, key has to be string.
TRI_ASSERT(false);
return hash;
}
return key->hash(hash);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief hashes an edge (_from case)
////////////////////////////////////////////////////////////////////////////////
static uint64_t HashElementEdgeFrom(void*, TRI_doc_mptr_t const* mptr,
bool byKey) {
TRI_ASSERT(mptr != nullptr);
uint64_t hash = 0x87654321;
if (!byKey) {
hash = (uint64_t)mptr;
hash = fasthash64(&hash, sizeof(hash), 0x56781234);
} else {
// Is identical to HashElementKey
VPackSlice tmp(mptr->vpack());
tmp = tmp.get(TRI_VOC_ATTRIBUTE_FROM);
TRI_ASSERT(tmp.isString());
hash = tmp.hash(hash);
}
return hash;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief hashes an edge (_to case)
////////////////////////////////////////////////////////////////////////////////
static uint64_t HashElementEdgeTo(void*, TRI_doc_mptr_t const* mptr,
bool byKey) {
TRI_ASSERT(mptr != nullptr);
uint64_t hash = 0x87654321;
if (!byKey) {
hash = (uint64_t)mptr;
hash = fasthash64(&hash, sizeof(hash), 0x56781234);
} else {
// Is identical to HashElementKey
VPackSlice tmp(mptr->vpack());
TRI_ASSERT(tmp.isObject());
tmp = tmp.get(TRI_VOC_ATTRIBUTE_TO);
TRI_ASSERT(tmp.isString());
hash = tmp.hash(hash);
}
return hash;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks if key and element match (_from case)
////////////////////////////////////////////////////////////////////////////////
static bool IsEqualKeyEdgeFrom(void*, VPackSlice const* left,
TRI_doc_mptr_t const* right) {
TRI_ASSERT(left != nullptr);
TRI_ASSERT(right != nullptr);
// left is a key
// right is an element, that is a master pointer
VPackSlice tmp(right->vpack());
tmp = tmp.get(TRI_VOC_ATTRIBUTE_FROM);
TRI_ASSERT(tmp.isString());
return *left == tmp;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks if key and element match (_to case)
////////////////////////////////////////////////////////////////////////////////
static bool IsEqualKeyEdgeTo(void*, VPackSlice const* left,
TRI_doc_mptr_t const* right) {
TRI_ASSERT(left != nullptr);
TRI_ASSERT(right != nullptr);
// left is a key
// right is an element, that is a master pointer
VPackSlice tmp(right->vpack());
tmp = tmp.get(TRI_VOC_ATTRIBUTE_TO);
TRI_ASSERT(tmp.isString());
return *left == tmp;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks for elements are equal (_from and _to case)
////////////////////////////////////////////////////////////////////////////////
static bool IsEqualElementEdge(void*, TRI_doc_mptr_t const* left,
TRI_doc_mptr_t const* right) {
return left == right;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks for elements are equal (_from case)
////////////////////////////////////////////////////////////////////////////////
static bool IsEqualElementEdgeFromByKey(void*,
TRI_doc_mptr_t const* left,
TRI_doc_mptr_t const* right) {
TRI_ASSERT(left != nullptr);
TRI_ASSERT(right != nullptr);
VPackSlice lSlice(left->vpack());
lSlice = lSlice.get(TRI_VOC_ATTRIBUTE_FROM);
TRI_ASSERT(lSlice.isString());
VPackSlice rSlice(right->vpack());
rSlice = rSlice.get(TRI_VOC_ATTRIBUTE_FROM);
TRI_ASSERT(rSlice.isString());
return lSlice == rSlice;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks for elements are equal (_to case)
////////////////////////////////////////////////////////////////////////////////
static bool IsEqualElementEdgeToByKey(void*,
TRI_doc_mptr_t const* left,
TRI_doc_mptr_t const* right) {
TRI_ASSERT(left != nullptr);
TRI_ASSERT(right != nullptr);
VPackSlice lSlice(left->vpack());
lSlice = lSlice.get(TRI_VOC_ATTRIBUTE_TO);
TRI_ASSERT(lSlice.isString());
VPackSlice rSlice(right->vpack());
rSlice = rSlice.get(TRI_VOC_ATTRIBUTE_TO);
TRI_ASSERT(rSlice.isString());
return lSlice == rSlice;
}
TRI_doc_mptr_t* EdgeIndexIterator::next() {
while (true) {
if (_position >= static_cast<size_t>(_keys.length())) {
// we're at the end of the lookup values
return nullptr;
}
if (_buffer == nullptr) {
// We start a new lookup
TRI_ASSERT(_position == 0);
_posInBuffer = 0;
_last = nullptr;
VPackSlice tmp = _keys.at(_position++);
if (tmp.isObject()) {
tmp = tmp.get(TRI_SLICE_KEY_EQUAL);
}
// TODO check if we have to decompose { eq: value } here!
_buffer = _index->lookupByKey(_trx, &tmp, _batchSize);
// fallthrough intentional
} else if (_posInBuffer >= _buffer->size()) {
// We have to refill the buffer
delete _buffer;
_buffer = nullptr;
_posInBuffer = 0;
if (_last != nullptr) {
_buffer = _index->lookupByKeyContinue(_trx, _last, _batchSize);
} else {
VPackSlice tmp = _keys.at(_position);
if (tmp.isObject()) {
tmp = tmp.get(TRI_SLICE_KEY_EQUAL);
}
// TODO check if we have to decompose { eq: value } here!
_buffer = _index->lookupByKey(_trx, &tmp, _batchSize);
}
}
if (!_buffer->empty()) {
// found something
_last = _buffer->back();
return _buffer->at(_posInBuffer++);
}
// found no result. now go to next lookup value in _keys
++_position;
// reset the _last value
_last = nullptr;
}
}
void EdgeIndexIterator::reset() {
_last = nullptr;
_position = 0;
_posInBuffer = 0;
// Free the vector space, not the content
delete _buffer;
_buffer = nullptr;
}
EdgeIndex::EdgeIndex(TRI_idx_iid_t iid, TRI_document_collection_t* collection)
: Index(iid, collection,
std::vector<std::vector<arangodb::basics::AttributeName>>(
{{{TRI_VOC_ATTRIBUTE_FROM, false}},
{{TRI_VOC_ATTRIBUTE_TO, false}}}),
false, false),
_edgesFrom(nullptr),
_edgesTo(nullptr),
_numBuckets(1) {
TRI_ASSERT(iid != 0);
if (collection != nullptr) {
// document is a nullptr in the coordinator case
_numBuckets = static_cast<size_t>(collection->_info.indexBuckets());
}
auto context = [this]() -> std::string { return this->context(); };
_edgesFrom = new TRI_EdgeIndexHash_t(HashElementKey, HashElementEdgeFrom,
IsEqualKeyEdgeFrom, IsEqualElementEdge,
IsEqualElementEdgeFromByKey, _numBuckets,
64, context);
_edgesTo = new TRI_EdgeIndexHash_t(
HashElementKey, HashElementEdgeTo, IsEqualKeyEdgeTo, IsEqualElementEdge,
IsEqualElementEdgeToByKey, _numBuckets, 64, context);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief create an index stub with a hard-coded selectivity estimate
/// this is used in the cluster coordinator case
////////////////////////////////////////////////////////////////////////////////
EdgeIndex::EdgeIndex(VPackSlice const& slice)
: Index(slice), _edgesFrom(nullptr), _edgesTo(nullptr), _numBuckets(1) {}
EdgeIndex::~EdgeIndex() {
delete _edgesTo;
delete _edgesFrom;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return a selectivity estimate for the index
////////////////////////////////////////////////////////////////////////////////
double EdgeIndex::selectivityEstimate() const {
if (_edgesFrom == nullptr || _edgesTo == nullptr) {
// use hard-coded selectivity estimate in case of cluster coordinator
return _selectivityEstimate;
}
// return average selectivity of the two index parts
double estimate = (_edgesFrom->selectivity() + _edgesTo->selectivity()) * 0.5;
TRI_ASSERT(estimate >= 0.0 &&
estimate <= 1.00001); // floating-point tolerance
return estimate;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return the memory usage for the index
////////////////////////////////////////////////////////////////////////////////
size_t EdgeIndex::memory() const {
TRI_ASSERT(_edgesFrom != nullptr);
TRI_ASSERT(_edgesTo != nullptr);
return _edgesFrom->memoryUsage() + _edgesTo->memoryUsage();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return a VelocyPack representation of the index
////////////////////////////////////////////////////////////////////////////////
void EdgeIndex::toVelocyPack(VPackBuilder& builder, bool withFigures) const {
Index::toVelocyPack(builder, withFigures);
// hard-coded
builder.add("unique", VPackValue(false));
builder.add("sparse", VPackValue(false));
}
////////////////////////////////////////////////////////////////////////////////
/// @brief return a VelocyPack representation of the index figures
////////////////////////////////////////////////////////////////////////////////
void EdgeIndex::toVelocyPackFigures(VPackBuilder& builder) const {
Index::toVelocyPackFigures(builder);
builder.add("buckets", VPackValue(_numBuckets));
}
int EdgeIndex::insert(arangodb::Transaction* trx, TRI_doc_mptr_t const* doc,
bool isRollback) {
auto element = const_cast<TRI_doc_mptr_t*>(doc);
_edgesFrom->insert(trx, element, true, isRollback);
try {
_edgesTo->insert(trx, element, true, isRollback);
} catch (...) {
_edgesFrom->remove(trx, element);
throw;
}
return TRI_ERROR_NO_ERROR;
}
int EdgeIndex::remove(arangodb::Transaction* trx, TRI_doc_mptr_t const* doc,
bool) {
_edgesFrom->remove(trx, doc);
_edgesTo->remove(trx, doc);
return TRI_ERROR_NO_ERROR;
}
int EdgeIndex::batchInsert(arangodb::Transaction* trx,
std::vector<TRI_doc_mptr_t const*> const* documents,
size_t numThreads) {
_edgesFrom->batchInsert(
trx, reinterpret_cast<std::vector<TRI_doc_mptr_t*> const*>(documents),
numThreads);
_edgesTo->batchInsert(
trx, reinterpret_cast<std::vector<TRI_doc_mptr_t*> const*>(documents),
numThreads);
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief looks up edges using the index, restarting at the edge pointed at
/// by next
////////////////////////////////////////////////////////////////////////////////
void EdgeIndex::lookup(arangodb::Transaction* trx,
TRI_edge_index_iterator_t const* edgeIndexIterator,
std::vector<TRI_doc_mptr_t>& result,
TRI_doc_mptr_t*& next, size_t batchSize) {
auto callback =
[&result](TRI_doc_mptr_t* data) -> void { result.emplace_back(*(data)); };
std::vector<TRI_doc_mptr_t*>* found = nullptr;
if (next == nullptr) {
VPackSlice edge = edgeIndexIterator->_edge;
if (edgeIndexIterator->_direction == TRI_EDGE_OUT) {
found = _edgesFrom->lookupByKey(trx, &edge, batchSize);
} else if (edgeIndexIterator->_direction == TRI_EDGE_IN) {
found = _edgesTo->lookupByKey(trx, &edge, batchSize);
} else {
TRI_ASSERT(false);
}
if (found != nullptr && found->size() != 0) {
next = found->back();
}
} else {
if (edgeIndexIterator->_direction == TRI_EDGE_OUT) {
found = _edgesFrom->lookupByKeyContinue(trx, next, batchSize);
} else if (edgeIndexIterator->_direction == TRI_EDGE_IN) {
found = _edgesTo->lookupByKeyContinue(trx, next, batchSize);
} else {
TRI_ASSERT(false);
}
if (found != nullptr && found->size() != 0) {
next = found->back();
} else {
next = nullptr;
}
}
if (found != nullptr) {
for (auto& v : *found) {
callback(v);
}
delete found;
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief provides a size hint for the edge index
////////////////////////////////////////////////////////////////////////////////
int EdgeIndex::sizeHint(arangodb::Transaction* trx, size_t size) {
// we assume this is called when setting up the index and the index
// is still empty
TRI_ASSERT(_edgesFrom->size() == 0);
// set an initial size for the index for some new nodes to be created
// without resizing
int err = _edgesFrom->resize(trx, static_cast<uint32_t>(size + 2049));
if (err != TRI_ERROR_NO_ERROR) {
return err;
}
// we assume this is called when setting up the index and the index
// is still empty
TRI_ASSERT(_edgesTo->size() == 0);
// set an initial size for the index for some new nodes to be created
// without resizing
return _edgesTo->resize(trx, static_cast<uint32_t>(size + 2049));
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks whether the index supports the condition
////////////////////////////////////////////////////////////////////////////////
bool EdgeIndex::supportsFilterCondition(
arangodb::aql::AstNode const* node,
arangodb::aql::Variable const* reference, size_t itemsInIndex,
size_t& estimatedItems, double& estimatedCost) const {
SimpleAttributeEqualityMatcher matcher(
{{arangodb::basics::AttributeName(TRI_VOC_ATTRIBUTE_FROM, false)},
{arangodb::basics::AttributeName(TRI_VOC_ATTRIBUTE_TO, false)}});
return matcher.matchOne(this, node, reference, itemsInIndex, estimatedItems,
estimatedCost);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief creates an IndexIterator for the given Condition
////////////////////////////////////////////////////////////////////////////////
IndexIterator* EdgeIndex::iteratorForCondition(
arangodb::Transaction* trx, IndexIteratorContext* context,
arangodb::aql::Ast* ast, arangodb::aql::AstNode const* node,
arangodb::aql::Variable const* reference, bool reverse) const {
TRI_ASSERT(node->type == aql::NODE_TYPE_OPERATOR_NARY_AND);
SimpleAttributeEqualityMatcher matcher(
{{arangodb::basics::AttributeName(TRI_VOC_ATTRIBUTE_FROM, false)},
{arangodb::basics::AttributeName(TRI_VOC_ATTRIBUTE_TO, false)}});
TRI_ASSERT(node->numMembers() == 1);
auto comp = node->getMember(0);
// assume a.b == value
auto attrNode = comp->getMember(0);
auto valNode = comp->getMember(1);
if (attrNode->type != aql::NODE_TYPE_ATTRIBUTE_ACCESS) {
// got value == a.b -> flip sides
attrNode = comp->getMember(1);
valNode = comp->getMember(0);
}
TRI_ASSERT(attrNode->type == aql::NODE_TYPE_ATTRIBUTE_ACCESS);
if (comp->type == aql::NODE_TYPE_OPERATOR_BINARY_EQ) {
// a.b == value
return createIterator(
trx, context, attrNode,
std::vector<arangodb::aql::AstNode const*>({valNode}));
}
if (comp->type == aql::NODE_TYPE_OPERATOR_BINARY_IN) {
// a.b IN values
if (!valNode->isArray()) {
return nullptr;
}
std::vector<arangodb::aql::AstNode const*> valNodes;
size_t const n = valNode->numMembers();
valNodes.reserve(n);
for (size_t i = 0; i < n; ++i) {
valNodes.emplace_back(valNode->getMemberUnchecked(i));
TRI_IF_FAILURE("EdgeIndex::iteratorValNodes") {
THROW_ARANGO_EXCEPTION(TRI_ERROR_DEBUG);
}
}
return createIterator(trx, context, attrNode, valNodes);
}
// operator type unsupported
return nullptr;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief specializes the condition for use with the index
////////////////////////////////////////////////////////////////////////////////
arangodb::aql::AstNode* EdgeIndex::specializeCondition(
arangodb::aql::AstNode* node,
arangodb::aql::Variable const* reference) const {
SimpleAttributeEqualityMatcher matcher(
{{arangodb::basics::AttributeName(TRI_VOC_ATTRIBUTE_FROM, false)},
{arangodb::basics::AttributeName(TRI_VOC_ATTRIBUTE_TO, false)}});
return matcher.specializeOne(this, node, reference);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief create the iterator
////////////////////////////////////////////////////////////////////////////////
IndexIterator* EdgeIndex::createIterator(
arangodb::Transaction* trx, IndexIteratorContext* context,
arangodb::aql::AstNode const* attrNode,
std::vector<arangodb::aql::AstNode const*> const& valNodes) const {
// only leave the valid elements in the vector
VPackBuilder keys;
keys.openArray();
for (auto const& valNode : valNodes) {
if (!valNode->isStringValue()) {
continue;
}
if (valNode->getStringLength() == 0) {
continue;
}
keys.openObject();
keys.add(TRI_SLICE_KEY_EQUAL, VPackValue(valNode->getStringValue()));
keys.close();
TRI_IF_FAILURE("EdgeIndex::collectKeys") {
THROW_ARANGO_EXCEPTION(TRI_ERROR_DEBUG);
}
}
TRI_IF_FAILURE("EdgeIndex::noIterator") {
THROW_ARANGO_EXCEPTION(TRI_ERROR_DEBUG);
}
keys.close();
// _from or _to?
bool const isFrom =
(strcmp(attrNode->getStringValue(), TRI_VOC_ATTRIBUTE_FROM) == 0);
return new EdgeIndexIterator(trx, isFrom ? _edgesFrom : _edgesTo, std::move(keys));
}
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