93 lines
3.6 KiB
C++
93 lines
3.6 KiB
C++
/*
|
|
* Copyright 2016 The Cartographer Authors
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#ifndef CARTOGRAPHER_MAPPING_INTERNAL_CONNECTED_COMPONENTS_H_
|
|
#define CARTOGRAPHER_MAPPING_INTERNAL_CONNECTED_COMPONENTS_H_
|
|
|
|
#include <map>
|
|
#include <unordered_map>
|
|
|
|
#include "absl/synchronization/mutex.h"
|
|
#include "cartographer/mapping/proto/connected_components.pb.h"
|
|
#include "cartographer/mapping/submaps.h"
|
|
|
|
namespace cartographer {
|
|
namespace mapping {
|
|
|
|
// A class that tracks the connectivity structure between trajectories.
|
|
//
|
|
// Connectivity includes both the count ("How many times have I _directly_
|
|
// connected trajectories i and j?") and the transitive connectivity.
|
|
//
|
|
// This class is thread-safe.
|
|
class ConnectedComponents {
|
|
public:
|
|
ConnectedComponents();
|
|
|
|
ConnectedComponents(const ConnectedComponents&) = delete;
|
|
ConnectedComponents& operator=(const ConnectedComponents&) = delete;
|
|
|
|
// Add a trajectory which is initially connected to only itself.
|
|
void Add(int trajectory_id) LOCKS_EXCLUDED(lock_);
|
|
|
|
// Connect two trajectories. If either trajectory is untracked, it will be
|
|
// tracked. This function is invariant to the order of its arguments. Repeated
|
|
// calls to Connect increment the connectivity count.
|
|
void Connect(int trajectory_id_a, int trajectory_id_b) LOCKS_EXCLUDED(lock_);
|
|
|
|
// Determines if two trajectories have been (transitively) connected. If
|
|
// either trajectory is not being tracked, returns false, except when it is
|
|
// the same trajectory, where it returns true. This function is invariant to
|
|
// the order of its arguments.
|
|
bool TransitivelyConnected(int trajectory_id_a, int trajectory_id_b)
|
|
LOCKS_EXCLUDED(lock_);
|
|
|
|
// Return the number of _direct_ connections between 'trajectory_id_a' and
|
|
// 'trajectory_id_b'. If either trajectory is not being tracked, returns 0.
|
|
// This function is invariant to the order of its arguments.
|
|
int ConnectionCount(int trajectory_id_a, int trajectory_id_b)
|
|
LOCKS_EXCLUDED(lock_);
|
|
|
|
// The trajectory IDs, grouped by connectivity.
|
|
std::vector<std::vector<int>> Components() LOCKS_EXCLUDED(lock_);
|
|
|
|
// The list of trajectory IDs that belong to the same connected component as
|
|
// 'trajectory_id'.
|
|
std::vector<int> GetComponent(int trajectory_id) LOCKS_EXCLUDED(lock_);
|
|
|
|
private:
|
|
// Find the representative and compresses the path to it.
|
|
int FindSet(int trajectory_id) EXCLUSIVE_LOCKS_REQUIRED(lock_);
|
|
void Union(int trajectory_id_a, int trajectory_id_b)
|
|
EXCLUSIVE_LOCKS_REQUIRED(lock_);
|
|
|
|
absl::Mutex lock_;
|
|
// Tracks transitive connectivity using a disjoint set forest, i.e. each
|
|
// entry points towards the representative for the given trajectory.
|
|
std::map<int, int> forest_ GUARDED_BY(lock_);
|
|
// Tracks the number of direct connections between a pair of trajectories.
|
|
std::map<std::pair<int, int>, int> connection_map_ GUARDED_BY(lock_);
|
|
};
|
|
|
|
// Returns a proto encoding connected components.
|
|
proto::ConnectedComponents ToProto(
|
|
std::vector<std::vector<int>> connected_components);
|
|
|
|
} // namespace mapping
|
|
} // namespace cartographer
|
|
|
|
#endif // CARTOGRAPHER_MAPPING_INTERNAL_CONNECTED_COMPONENTS_H_
|