| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| **/ |
| |
| #ifndef QUICKSTEP_TRANSACTION_CYCLE_DETECTOR_HPP_ |
| #define QUICKSTEP_TRANSACTION_CYCLE_DETECTOR_HPP_ |
| |
| #include <memory> |
| #include <unordered_set> |
| #include <vector> |
| |
| #include "transaction/DirectedGraph.hpp" |
| #include "transaction/StronglyConnectedComponents.hpp" |
| #include "utility/Macros.hpp" |
| |
| namespace quickstep { |
| namespace transaction { |
| |
| /** \addtogroup Transaction |
| * @{ |
| */ |
| |
| /** |
| * @brief Class for running cycle detection algorithm on directed graph. |
| */ |
| class CycleDetector { |
| public: |
| /** |
| * @brief Constructor for DirectedGraph. |
| * |
| * @param wait_for_graph Pointer to a directed wait-for graph. |
| */ |
| explicit CycleDetector(DirectedGraph *wait_for_graph); |
| |
| /** |
| * @brief Calculate which nodes should be killed to eliminate all cycles |
| * in the graph. |
| * |
| * @return Vector of node ids that should be killed to break all cycles. |
| */ |
| std::vector<DirectedGraph::node_id> chooseVictimsToBreakCycle() const; |
| |
| private: |
| std::vector<DirectedGraph::node_id> chooseVictimsInComponent( |
| const std::vector<DirectedGraph::node_id> &nodes) const; |
| |
| inline DirectedGraph::node_id chooseVictim( |
| const std::unordered_set<DirectedGraph::node_id> &nodes_set) const { |
| // TODO(Hakan): This is very inefficient scheme, however in the |
| // future, we can use the transaction's priority |
| // as the victim selection parameter. |
| return *(nodes_set.begin()); |
| } |
| |
| // Checks whether the nodes in the set make a cycle. |
| bool hasCycle(const std::unordered_set<DirectedGraph::node_id> &within) const; |
| |
| DirectedGraph *wait_for_graph_; |
| |
| std::unique_ptr<StronglyConnectedComponents> strongly_connected_components_; |
| |
| DISALLOW_COPY_AND_ASSIGN(CycleDetector); |
| }; |
| |
| /** @} */ |
| |
| } // namespace transaction |
| } // namespace quickstep |
| |
| #endif // QUICKSTEP_TRANSACTION_CYCLE_DETECTOR_HPP_ |