mirror of https://gitee.com/bigwinds/arangodb
69 lines
2.5 KiB
C++
69 lines
2.5 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2016 ArangoDB 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 Simon Grätzer
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGODB_PREGEL_ALGOS_SCC_H
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#define ARANGODB_PREGEL_ALGOS_SCC_H 1
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#include "Pregel/Algorithm.h"
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#include "Pregel/CommonFormats.h"
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namespace arangodb {
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namespace pregel {
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namespace algos {
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/// Finds strongly connected components of the graph.
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///
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/// 1. Each vertex starts with its vertex id as its "color".
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/// 2. Remove vertices which cannot be in a SCC (no incoming or no outgoing
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/// edges)
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/// 3. Propagate the color forward from each vertex, accept a neighbor's color
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/// if it's smaller than yours.
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/// At convergence, vertices with the same color represents all nodes that
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/// are visitable from the root of that color.
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/// 4. Reverse the graph.
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/// 5. Start at all roots, walk the graph. Visit a neighbor if it has the same
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/// color as you.
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/// All nodes visited belongs to the SCC identified by the root color.
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struct SCC : public SimpleAlgorithm<SCCValue, int8_t, SenderMessage<uint64_t>> {
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public:
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explicit SCC(application_features::ApplicationServer& server, VPackSlice userParams)
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: SimpleAlgorithm<SCCValue, int8_t, SenderMessage<uint64_t>>(server, "SCC", userParams) {
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}
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GraphFormat<SCCValue, int8_t>* inputFormat() const override;
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MessageFormat<SenderMessage<uint64_t>>* messageFormat() const override {
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return new SenderMessageFormat<uint64_t>();
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}
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VertexComputation<SCCValue, int8_t, SenderMessage<uint64_t>>* createComputation(
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WorkerConfig const*) const override;
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MasterContext* masterContext(VPackSlice userParams) const override;
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IAggregator* aggregator(std::string const& name) const override;
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};
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} // namespace algos
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} // namespace pregel
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} // namespace arangodb
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#endif
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