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Codechange: [Linkgraph] Skip MCF source node Dijkstra when all demand satisfied 

MCF Dijkstra iterations are executed for all source nodes in a round-robin order.
Source nodes typically require different numbers of MCF Dijkstra iterations
to satisfy all of their demand.
This change is to avoid performing MCF Dijkstra iterations on source nodes which
have already been fully satisfied.
pull/7921/head
Jonathan G Rennison 2019-10-06 17:02:38 +01:00 committed by Niels Martin Hansen
parent 190e074287
commit 6e7117e04c
1 changed files with 16 additions and 1 deletions
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17
src/linkgraph/mcf.cpp
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@ -494,13 +494,17 @@ MCF1stPass::MCF1stPass(LinkGraphJob &job) : MultiCommodityFlow(job)
uint size = job.Size(); uint size = job.Size();
uint accuracy = job.Settings().accuracy; uint accuracy = job.Settings().accuracy;
bool more_loops; bool more_loops;
std::vector<bool> finished_sources(size);
do { do {
more_loops = false; more_loops = false;
for (NodeID source = 0; source < size; ++source) { for (NodeID source = 0; source < size; ++source) {
if (finished_sources[source]) continue;
/* First saturate the shortest paths. */ /* First saturate the shortest paths. */
this->Dijkstra<DistanceAnnotation, GraphEdgeIterator>(source, paths); this->Dijkstra<DistanceAnnotation, GraphEdgeIterator>(source, paths);
bool source_demand_left = false;
for (NodeID dest = 0; dest < size; ++dest) { for (NodeID dest = 0; dest < size; ++dest) {
Edge edge = job[source][dest]; Edge edge = job[source][dest];
if (edge.UnsatisfiedDemand() > 0) { if (edge.UnsatisfiedDemand() > 0) {
@ -518,8 +522,10 @@ MCF1stPass::MCF1stPass(LinkGraphJob &job) : MultiCommodityFlow(job)
path->GetFreeCapacity() > INT_MIN) { path->GetFreeCapacity() > INT_MIN) {
this->PushFlow(edge, path, accuracy, UINT_MAX); this->PushFlow(edge, path, accuracy, UINT_MAX);
} }
if (edge.UnsatisfiedDemand() > 0) source_demand_left = true;
} }
} }
finished_sources[source] = !source_demand_left;
this->CleanupPaths(source, paths); this->CleanupPaths(source, paths);
} }
} while (more_loops || this->EliminateCycles()); } while (more_loops || this->EliminateCycles());
@ -537,18 +543,27 @@ MCF2ndPass::MCF2ndPass(LinkGraphJob &job) : MultiCommodityFlow(job)
uint size = job.Size(); uint size = job.Size();
uint accuracy = job.Settings().accuracy; uint accuracy = job.Settings().accuracy;
bool demand_left = true; bool demand_left = true;
std::vector<bool> finished_sources(size);
while (demand_left) { while (demand_left) {
demand_left = false; demand_left = false;
for (NodeID source = 0; source < size; ++source) { for (NodeID source = 0; source < size; ++source) {
if (finished_sources[source]) continue;
this->Dijkstra<CapacityAnnotation, FlowEdgeIterator>(source, paths); this->Dijkstra<CapacityAnnotation, FlowEdgeIterator>(source, paths);
bool source_demand_left = false;
for (NodeID dest = 0; dest < size; ++dest) { for (NodeID dest = 0; dest < size; ++dest) {
Edge edge = this->job[source][dest]; Edge edge = this->job[source][dest];
Path *path = paths[dest]; Path *path = paths[dest];
if (edge.UnsatisfiedDemand() > 0 && path->GetFreeCapacity() > INT_MIN) { if (edge.UnsatisfiedDemand() > 0 && path->GetFreeCapacity() > INT_MIN) {
this->PushFlow(edge, path, accuracy, UINT_MAX); this->PushFlow(edge, path, accuracy, UINT_MAX);
if (edge.UnsatisfiedDemand() > 0) demand_left = true; if (edge.UnsatisfiedDemand() > 0) {
demand_left = true;
source_demand_left = true;
} }
} }
}
finished_sources[source] = !source_demand_left;
this->CleanupPaths(source, paths); this->CleanupPaths(source, paths);
} }
} }