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arangodb/arangod/Pregel/Algos/SSSP.cpp

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2016 ArangoDB 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 Simon Grätzer
////////////////////////////////////////////////////////////////////////////////
#include "SSSP.h"
#include "Pregel/Algorithm.h"
#include "Pregel/GraphStore.h"
#include "Pregel/IncomingCache.h"
#include "Pregel/VertexComputation.h"
using namespace arangodb;
using namespace arangodb::pregel;
using namespace arangodb::pregel::algos;
struct SSSPComputation : public VertexComputation<int64_t, int64_t, int64_t> {
SSSPComputation() {}
void compute(MessageIterator<int64_t> const& messages) override {
int64_t tmp = vertexData();
for (const int64_t* msg : messages) {
if (*msg < tmp) {
tmp = *msg;
};
}
int64_t* state = mutableVertexData();
if (tmp < *state || (tmp == 0 && localSuperstep() == 0)) {
*state = tmp; // update state
RangeIterator<Edge<int64_t>> edges = getEdges();
for (; edges.hasMore(); ++edges) {
Edge<int64_t>* edge = *edges;
int64_t val = edge->data() + tmp;
sendMessage(edge, val);
}
}
voteHalt();
}
};
uint32_t SSSPAlgorithm::messageBatchSize(WorkerConfig const& config,
MessageStats const& stats) const {
if (config.localSuperstep() <= 1) {
return 5;
} else {
double msgsPerSec = stats.sendCount / stats.superstepRuntimeSecs;
msgsPerSec /= config.parallelism(); // per thread
return msgsPerSec > 100.0 ? (uint32_t)msgsPerSec : 100;
}
}
VertexComputation<int64_t, int64_t, int64_t>* SSSPAlgorithm::createComputation(
WorkerConfig const* config) const {
return new SSSPComputation();
}
struct SSSPGraphFormat : public InitGraphFormat<int64_t, int64_t> {
std::string _sourceDocId, resultField;
public:
SSSPGraphFormat(application_features::ApplicationServer& server,
std::string const& source, std::string const& result)
: InitGraphFormat<int64_t, int64_t>(server, result, 0, 1),
_sourceDocId(source) {}
void copyVertexData(std::string const& documentId, arangodb::velocypack::Slice document,
int64_t& targetPtr) override {
targetPtr = (documentId == _sourceDocId) ? 0 : INT64_MAX;
}
bool buildEdgeDocument(arangodb::velocypack::Builder& b,
const int64_t* targetPtr, size_t size) const override {
return false;
}
};
GraphFormat<int64_t, int64_t>* SSSPAlgorithm::inputFormat() const {
return new SSSPGraphFormat(_server, _sourceDocumentId, _resultField);
}
struct SSSPCompensation : public VertexCompensation<int64_t, int64_t, int64_t> {
SSSPCompensation() {}
void compensate(bool inLostPartition) override {
if (inLostPartition) {
int64_t* data = mutableVertexData();
*data = INT64_MAX;
}
voteActive();
}
};
VertexCompensation<int64_t, int64_t, int64_t>* SSSPAlgorithm::createCompensation(
WorkerConfig const* config) const {
return new SSSPCompensation();
}