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Add heuristic approach to assign edge-based partition IDs

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that minimize number of faked source/destination nodes in
the edge case: a single backward edge will be placed
in other than node u partion
This commit is contained in:
Michael Krasnyk 2017-03-13 11:47:07 +01:00 committed by Patrick Niklaus
parent 40094ceeab
commit c6e9cc8024
1 changed files with 35 additions and 1 deletions
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36
src/partition/partitioner.cpp
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@ -151,12 +151,46 @@ int Partitioner::Run(const PartitionConfig &config)
{
// Can use partition_ids[u/v] as partition for edge based graph `node_id`
edge_based_partition_ids[node] = node_based_partition_ids[u];
auto edges = edge_based_graph->GetAdjacentEdgeRange(node);
if (edges.size() == 1)
{ // Check the edge case with one adjacent edge-based backward edge
auto edge = edges.front();
auto other = edge_based_graph->GetTarget(edge);
auto &data = edge_based_graph->GetEdgeData(edge);
auto other_node_based_nodes = mapping.Lookup(other);
if (data.backward &&
node_based_partition_ids[other_node_based_nodes.u] !=
node_based_partition_ids[u])
{ // use id of other node if the edge [other_u, other_v] -> [u,v] is a single edge
// and nodes other_[u,v] are in different node-based partitions
edge_based_partition_ids[node] =
node_based_partition_ids[other_node_based_nodes.u];
}
}
}
else
{
// Border nodes u,v - need to be resolved.
// FIXME: just pick one side for now. See #3205.
edge_based_partition_ids[node] = node_based_partition_ids[u];
bool use_u = false;
for (auto edge : edge_based_graph->GetAdjacentEdgeRange(node))
{
auto other = edge_based_graph->GetTarget(edge);
auto &data = edge_based_graph->GetEdgeData(edge);
auto other_node_based_nodes = mapping.Lookup(other);
if (data.backward)
{ // can use id of u if [other_u, other_v] -> [u,v] is in the same partition as u
BOOST_ASSERT(u == other_node_based_nodes.v);
use_u |= node_based_partition_ids[u] ==
node_based_partition_ids[other_node_based_nodes.u];
}
}
// Use partition that introduce less cross cell connections
edge_based_partition_ids[node] = node_based_partition_ids[use_u ? u : v];
}
}