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Store flag for artificial bounary edges and walk border nodes in ebg

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Daniel J. Hofmann 2017-02-10 12:08:46 +01:00 committed by Patrick Niklaus
parent 5015e12d59
commit e589ab814d
2 changed files with 25 additions and 31 deletions
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3
include/partition/edge_based_graph_reader.hpp
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@ -23,7 +23,7 @@ struct EdgeBasedGraphEdgeData
NodeID edge_id : 31;
// Artificial edge used to fixup partitioning, see #3205.
// These artificial edges have invalid weight / duration.
std::uint32_t is_boundary_arc : 1;
bool is_boundary_arc : 1;
EdgeWeight weight;
EdgeWeight duration : 30;
std::uint32_t forward : 1;
@ -140,7 +140,6 @@ struct EdgeBasedGraphReader
forward_edge.data.forward = reverse_edge.data.backward = true;
forward_edge.data.backward = reverse_edge.data.forward = false;
// remove parallel edges
while (i < edges.size() && edges[i].source == source && edges[i].target == target)
{

53
src/partition/partitioner.cpp
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@ -156,8 +156,7 @@ int Partitioner::Run(const PartitionConfig &config)
const auto &partition_ids = recursive_bisection.BisectionIDs();
// Keyed by ebg node - stores flag if ebg node is border node or not.
std::vector<bool> is_edge_based_border_node(edge_based_graph->GetNumberOfNodes());
std::vector<NodeID> edge_based_border_nodes;
// Extract edge based border nodes, based on node based partition and mapping.
for (const auto node_id : util::irange(0u, edge_based_graph->GetNumberOfNodes()))
@ -170,45 +169,41 @@ int Partitioner::Run(const PartitionConfig &config)
if (partition_ids[u] == partition_ids[v])
{
// Can use partition_ids[u/v] as partition for edge based graph `node_id`
is_edge_based_border_node[node_id] = false;
}
else
{
// Border nodes u,v - need to be resolved. What we can do:
// - 1) Pick one of the partitions randomly or by minimizing border edges.
// - 2) Or: modify edge based graph, introducing artificial edges. We do this.
is_edge_based_border_node[node_id] = true;
// Border nodes u,v - need to be resolved.
edge_based_border_nodes.push_back(node_id);
}
}
const auto num_border_nodes =
std::count(begin(is_edge_based_border_node), end(is_edge_based_border_node), true);
util::Log() << "Fixing " << edge_based_border_nodes.size() << " edge based graph border nodes";
util::Log() << "Fixing " << num_border_nodes << " edge based graph border nodes";
std::vector<std::pair<NodeID, EdgeBasedGraphEdgeData>> incoming_edges;
// Keyed by ebg node - stores associated border nodes for nodes
std::unordered_map<NodeID, NodeID> edge_based_border_node;
edge_based_border_node.reserve(num_border_nodes);
// For all edges in the edge based graph: if they start and end in different partitions
// introduce artificial nodes and re-wire incoming / outgoing edges to these artificial ones.
for (const auto source : util::irange(0u, edge_based_graph->GetNumberOfNodes()))
for (const auto border_node : edge_based_border_nodes)
{
for (auto edge : edge_based_graph->GetAdjacentEdgeRange(source))
for (const auto edge : edge_based_graph->GetAdjacentEdgeRange(border_node))
{
const auto target = edge_based_graph->GetTarget(edge);
const auto &data = edge_based_graph->GetEdgeData(edge);
const auto opposite_edge = edge_based_graph->FindEdge(target, source);
if (!is_edge_based_border_node[source] || !is_edge_based_border_node[target])
continue;
// TODO: assign and store partition ids to new nodes
const auto artificial_node = edge_based_graph->InsertNode();
EdgeBasedGraphEdgeData dummy{SPECIAL_EDGEID, /*is_boundary_arc=*/1, 0, 0, false, false};
if (data.backward)
{
incoming_edges.emplace_back(edge_based_graph->GetTarget(edge), data);
edge_based_graph->DeleteEdge(border_node, edge);
}
}
const auto artificial = edge_based_graph->InsertNode();
EdgeBasedGraphEdgeData dummy{SPECIAL_EDGEID, /*is_boundary_arc=*/true, 0, 0, false, false};
for (const auto edge : incoming_edges)
{
edge_based_graph->InsertEdge(edge.first, artificial, edge.second);
}
incoming_edges.clear();
}
return 0;