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arangodb/arangod/Aql/ShortestPathNode.cpp

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/// @brief Implementation of Shortest Path Execution Node
///
/// @file arangod/Aql/ShortestPathNode.cpp
///
/// DISCLAIMER
///
/// Copyright 2010-2014 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 Michael Hackstein
/// @author Copyright 2015, ArangoDB GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////
#include "ShortestPathNode.h"
#include "Aql/Ast.h"
#include "Aql/ExecutionPlan.h"
#include "Indexes/Index.h"
#include "Utils/CollectionNameResolver.h"
#include "V8Server/V8Traverser.h"
#include <velocypack/Iterator.h>
#include <velocypack/velocypack-aliases.h>
using namespace arangodb::basics;
using namespace arangodb::aql;
static void parseNodeInput(AstNode const* node, std::string& id,
Variable const*& variable) {
switch (node->type) {
case NODE_TYPE_REFERENCE:
variable = static_cast<Variable*>(node->getData());
id = "";
break;
case NODE_TYPE_VALUE:
if (node->value.type != VALUE_TYPE_STRING) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_PARSE,
"invalid start vertex. Must either be "
"an _id string or an object with _id.");
}
variable = nullptr;
id = node->getString();
break;
default:
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_PARSE,
"invalid start vertex. Must either be an "
"_id string or an object with _id.");
}
}
static TRI_edge_direction_e parseDirection (uint64_t dirNum) {
switch (dirNum) {
case 0:
return TRI_EDGE_ANY;
case 1:
return TRI_EDGE_IN;
case 2:
return TRI_EDGE_OUT;
default:
THROW_ARANGO_EXCEPTION_MESSAGE(
TRI_ERROR_QUERY_PARSE,
"direction can only be INBOUND, OUTBOUND or ANY");
}
}
ShortestPathNode::ShortestPathNode(ExecutionPlan* plan, size_t id,
TRI_vocbase_t* vocbase, uint64_t direction,
AstNode const* start, AstNode const* target,
AstNode const* graph,
ShortestPathOptions const& options)
: ExecutionNode(plan, id),
_vocbase(vocbase),
_vertexOutVariable(nullptr),
_edgeOutVariable(nullptr),
_inStartVariable(nullptr),
_inTargetVariable(nullptr),
_graphObj(nullptr),
_options(options) {
TRI_ASSERT(_vocbase != nullptr);
TRI_ASSERT(start != nullptr);
TRI_ASSERT(target != nullptr);
TRI_ASSERT(graph != nullptr);
TRI_edge_direction_e baseDirection = parseDirection(direction);
if (graph->type == NODE_TYPE_COLLECTION_LIST) {
size_t edgeCollectionCount = graph->numMembers();
auto resolver = std::make_unique<CollectionNameResolver>(vocbase);
_graphInfo.openArray();
_edgeColls.reserve(edgeCollectionCount);
_directions.reserve(edgeCollectionCount);
// List of edge collection names
for (size_t i = 0; i < edgeCollectionCount; ++i) {
auto col = graph->getMember(i);
if (col->type == NODE_TYPE_DIRECTION) {
// We have a collection with special direction.
TRI_ASSERT(col->getMember(0)->isIntValue());
TRI_edge_direction_e dir = parseDirection(col->getMember(0)->getIntValue());
_directions.emplace_back(dir);
col = col->getMember(1);
} else {
_directions.emplace_back(baseDirection);
}
std::string eColName = col->getString();
auto eColType = resolver->getCollectionTypeCluster(eColName);
if (eColType != TRI_COL_TYPE_EDGE) {
std::string msg("collection type invalid for collection '" +
std::string(eColName) +
": expecting collection type 'edge'");
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_ARANGO_COLLECTION_TYPE_INVALID,
msg);
}
_graphInfo.add(VPackValue(eColName));
_edgeColls.emplace_back(std::move(eColName));
}
_graphInfo.close();
} else {
if (_edgeColls.empty()) {
if (graph->isStringValue()) {
std::string graphName = graph->getString();
_graphInfo.add(VPackValue(graphName));
_graphObj = plan->getAst()->query()->lookupGraphByName(graphName);
if (_graphObj == nullptr) {
THROW_ARANGO_EXCEPTION(TRI_ERROR_GRAPH_NOT_FOUND);
}
auto eColls = _graphObj->edgeCollections();
size_t length = eColls.size();
if (length == 0) {
THROW_ARANGO_EXCEPTION(TRI_ERROR_GRAPH_EMPTY);
}
_edgeColls.reserve(length);
_directions.reserve(length);
for (const auto& n : eColls) {
_edgeColls.push_back(n);
_directions.emplace_back(baseDirection);
}
}
}
}
parseNodeInput(start, _startVertexId, _inStartVariable);
parseNodeInput(target, _targetVertexId, _inTargetVariable);
}
ShortestPathNode::ShortestPathNode(ExecutionPlan* plan, size_t id,
TRI_vocbase_t* vocbase,
std::vector<std::string> const& edgeColls,
std::vector<TRI_edge_direction_e> const& directions,
Variable const* inStartVariable,
std::string const& startVertexId,
Variable const* inTargetVariable,
std::string const& targetVertexId,
ShortestPathOptions const& options)
: ExecutionNode(plan, id),
_vocbase(vocbase),
_vertexOutVariable(nullptr),
_edgeOutVariable(nullptr),
_inStartVariable(inStartVariable),
_startVertexId(startVertexId),
_inTargetVariable(inTargetVariable),
_targetVertexId(targetVertexId),
_directions(directions),
_graphObj(nullptr),
_options(options) {
_graphInfo.openArray();
for (auto const& it : edgeColls) {
_edgeColls.emplace_back(it);
_graphInfo.add(VPackValue(it));
}
_graphInfo.close();
}
void ShortestPathNode::fillOptions(arangodb::traverser::ShortestPathOptions& opts) const {
if (!_options.weightAttribute.empty()) {
opts.useWeight = true;
opts.weightAttribute = _options.weightAttribute;
opts.defaultWeight = _options.defaultWeight;
} else {
opts.useWeight = false;
}
}
ShortestPathNode::ShortestPathNode(ExecutionPlan* plan,
arangodb::velocypack::Slice const& base)
: ExecutionNode(plan, base),
_vocbase(plan->getAst()->query()->vocbase()),
_vertexOutVariable(nullptr),
_edgeOutVariable(nullptr),
_inStartVariable(nullptr),
_inTargetVariable(nullptr),
_graphObj(nullptr) {
// Directions
VPackSlice dirList = base.get("directions");
for (auto const& it : VPackArrayIterator(dirList)) {
uint64_t dir = arangodb::basics::VelocyPackHelper::stringUInt64(it);
TRI_edge_direction_e d;
switch (dir) {
case 0:
d = TRI_EDGE_ANY;
break;
case 1:
d = TRI_EDGE_IN;
break;
case 2:
d = TRI_EDGE_OUT;
break;
default:
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_BAD_PARAMETER,
"Invalid direction value");
break;
}
_directions.emplace_back(d);
}
// Start Vertex
if (base.hasKey("startInVariable")) {
_inStartVariable = varFromVPack(plan->getAst(), base, "startInVariable");
} else {
VPackSlice v = base.get("startVertexId");
if (!v.isString()) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_BAD_JSON_PLAN,
"start vertex must be a string");
}
_startVertexId = v.copyString();
if (_startVertexId.empty()) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_BAD_JSON_PLAN,
"start vertex mustn't be empty");
}
}
// Target Vertex
if (base.hasKey("targetInVariable")) {
_inTargetVariable = varFromVPack(plan->getAst(), base, "targetInVariable");
} else {
VPackSlice v = base.get("targetVertexId");
if (!v.isString()) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_BAD_JSON_PLAN,
"target vertex must be a string");
}
_targetVertexId = v.copyString();
if (_targetVertexId.empty()) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_BAD_JSON_PLAN,
"target vertex mustn't be empty");
}
}
std::string graphName;
if (base.hasKey("graph") && (base.get("graph").isString())) {
graphName = base.get("graph").copyString();
if (base.hasKey("graphDefinition")) {
_graphObj = plan->getAst()->query()->lookupGraphByName(graphName);
if (_graphObj == nullptr) {
THROW_ARANGO_EXCEPTION(TRI_ERROR_GRAPH_NOT_FOUND);
}
auto eColls = _graphObj->edgeCollections();
for (auto const& n : eColls) {
_edgeColls.push_back(n);
}
} else {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_BAD_JSON_PLAN,
"missing graphDefinition.");
}
} else {
_graphInfo.add(base.get("graph"));
if (!_graphInfo.slice().isArray()) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_BAD_JSON_PLAN,
"graph has to be an array.");
}
// List of edge collection names
for (auto const& it : VPackArrayIterator(_graphInfo.slice())) {
if (!it.isString()) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_QUERY_BAD_JSON_PLAN,
"graph has to be an array of strings.");
}
_edgeColls.emplace_back(it.copyString());
}
if (_edgeColls.empty()) {
THROW_ARANGO_EXCEPTION_MESSAGE(
TRI_ERROR_QUERY_BAD_JSON_PLAN,
"graph has to be a non empty array of strings.");
}
}
// Out variables
if (base.hasKey("vertexOutVariable")) {
_vertexOutVariable = varFromVPack(plan->getAst(), base, "vertexOutVariable");
}
if (base.hasKey("edgeOutVariable")) {
_edgeOutVariable = varFromVPack(plan->getAst(), base, "edgeOutVariable");
}
// Flags
if (base.hasKey("shortestPathFlags")) {
_options = ShortestPathOptions(base);
}
}
void ShortestPathNode::toVelocyPackHelper(VPackBuilder& nodes,
bool verbose) const {
ExecutionNode::toVelocyPackHelperGeneric(nodes,
verbose); // call base class method
nodes.add("database", VPackValue(_vocbase->name()));
nodes.add("graph", _graphInfo.slice());
nodes.add(VPackValue("directions"));
{
VPackArrayBuilder guard(&nodes);
for (auto const& d : _directions) {
nodes.add(VPackValue(d));
}
}
// In variables
if (usesStartInVariable()) {
nodes.add(VPackValue("startInVariable"));
startInVariable()->toVelocyPack(nodes);
} else {
nodes.add("startVertexId", VPackValue(_startVertexId));
}
if (usesTargetInVariable()) {
nodes.add(VPackValue("targetInVariable"));
targetInVariable()->toVelocyPack(nodes);
} else {
nodes.add("targetVertexId", VPackValue(_targetVertexId));
}
if (_graphObj != nullptr) {
nodes.add(VPackValue("graphDefinition"));
_graphObj->toVelocyPack(nodes, verbose);
}
// Out variables
if (usesVertexOutVariable()) {
nodes.add(VPackValue("vertexOutVariable"));
vertexOutVariable()->toVelocyPack(nodes);
}
if (usesEdgeOutVariable()) {
nodes.add(VPackValue("edgeOutVariable"));
edgeOutVariable()->toVelocyPack(nodes);
}
nodes.add(VPackValue("shortestPathFlags"));
_options.toVelocyPack(nodes);
// And close it:
nodes.close();
}
ExecutionNode* ShortestPathNode::clone(ExecutionPlan* plan,
bool withDependencies,
bool withProperties) const {
auto c = new ShortestPathNode(plan, _id, _vocbase, _edgeColls, _directions,
_inStartVariable, _startVertexId,
_inTargetVariable, _targetVertexId, _options);
if (usesVertexOutVariable()) {
auto vertexOutVariable = _vertexOutVariable;
if (withProperties) {
vertexOutVariable =
plan->getAst()->variables()->createVariable(vertexOutVariable);
}
TRI_ASSERT(vertexOutVariable != nullptr);
c->setVertexOutput(vertexOutVariable);
}
if (usesEdgeOutVariable()) {
auto edgeOutVariable = _edgeOutVariable;
if (withProperties) {
edgeOutVariable =
plan->getAst()->variables()->createVariable(edgeOutVariable);
}
TRI_ASSERT(edgeOutVariable != nullptr);
c->setEdgeOutput(edgeOutVariable);
}
cloneHelper(c, plan, withDependencies, withProperties);
return static_cast<ExecutionNode*>(c);
}
double ShortestPathNode::estimateCost(size_t& nrItems) const {
// Standard estimation for Shortest path is O(|E| + |V|*LOG(|V|))
// At this point we know |E| but do not know |V|.
size_t incoming = 0;
double depCost = _dependencies.at(0)->getCost(incoming);
auto trx = _plan->getAst()->query()->trx();
auto collections = _plan->getAst()->query()->collections();
size_t edgesCount = 0;
double nodesEstimate = 0;
TRI_ASSERT(collections != nullptr);
for (auto const& it : _edgeColls) {
auto collection = collections->get(it);
if (collection == nullptr) {
THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL,
"unexpected pointer for collection");
}
size_t edges = collection->count();
auto indexes = trx->indexesForCollection(collection->name);
for (auto const& index : indexes) {
if (index->type() == arangodb::Index::IndexType::TRI_IDX_TYPE_EDGE_INDEX) {
// We can only use Edge Index
if (index->hasSelectivityEstimate()) {
nodesEstimate += edges * index->selectivityEstimate();
} else {
// Hard-coded fallback should not happen
nodesEstimate += edges * 0.01;
}
break;
}
}
edgesCount += edges;
}
nrItems = edgesCount + static_cast<size_t>(std::log2(nodesEstimate) * nodesEstimate);
return depCost + nrItems;
}
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