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Linkgraph: Split demand annotations from edge flow annotations

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Use sparse storage format for demand annotations
This commit is contained in:
Jonathan G Rennison
2023-01-05 01:05:40 +00:00
parent 9bc5f69a19
commit 55473bc730
6 changed files with 74 additions and 65 deletions
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24
src/linkgraph/demands.cpp
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@@ -244,7 +244,8 @@ void AsymmetricScalerEq::SetDemands(LinkGraphJob &job, NodeID from_id, NodeID to
*/
inline void Scaler::SetDemands(LinkGraphJob &job, NodeID from_id, NodeID to_id, uint demand_forw)
{
job[from_id].DeliverSupply(to_id, demand_forw);
job[from_id].DeliverSupply(demand_forw);
job.demand_map[std::make_pair(from_id, to_id)] += demand_forw;
}
/**
@@ -476,4 +477,25 @@ DemandCalculator::DemandCalculator(LinkGraphJob &job) :
first_unseen++;
}
} while (first_unseen < size);
if (job.demand_map.size() > 0) {
job.demand_annotation_store.resize(job.demand_map.size());
size_t start_idx = 0;
size_t idx = 0;
NodeID last_from = job.demand_map.begin()->first.first;
auto flush = [&]() {
job[last_from].SetDemandAnnotations({ job.demand_annotation_store.data() + start_idx, idx - start_idx });
};
for (auto &iter : job.demand_map) {
if (iter.first.first != last_from) {
flush();
last_from = iter.first.first;
start_idx = idx;
}
job.demand_annotation_store[idx] = { iter.first.second, iter.second, iter.second };
idx++;
}
flush();
job.demand_map.clear();
}
}

2
src/linkgraph/linkgraphjob.cpp
View File

@@ -212,9 +212,7 @@ void LinkGraphJob::Init()
*/
void LinkGraphJob::EdgeAnnotation::Init()
{
this->demand = 0;
this->flow = 0;
this->unsatisfied_demand = 0;
}
/**

64
src/linkgraph/linkgraphjob.h
View File

@@ -31,13 +31,21 @@ extern LinkGraphJobPool _link_graph_job_pool;
* Class for calculation jobs to be run on link graphs.
*/
class LinkGraphJob : public LinkGraphJobPool::PoolItem<&_link_graph_job_pool>{
public:
/**
* Annotation for a link graph demand edge.
*/
struct DemandAnnotation {
NodeID dest; ///< Target node
uint demand = 0; ///< Transport demand between the nodes.
uint unsatisfied_demand = 0; ///< Demand over this edge that hasn't been satisfied yet.
};
private:
/**
* Annotation for a link graph edge.
* Annotation for a link graph flow edge.
*/
struct EdgeAnnotation {
uint demand; ///< Transport demand between the nodes.
uint unsatisfied_demand; ///< Demand over this edge that hasn't been satisfied yet.
uint flow; ///< Planned flow over this edge.
void Init();
};
@@ -50,6 +58,7 @@ private:
uint received_demand; ///< Received demand towards this node.
PathList paths; ///< Paths through this node, sorted so that those with flow == 0 are in the back.
FlowStatMap flows; ///< Planned flows to other nodes.
span<DemandAnnotation> demands; ///< Demand annotations belonging to this node.
void Init(uint supply);
};
@@ -79,6 +88,9 @@ protected:
public:
btree::btree_map<std::pair<NodeID, NodeID>, uint> demand_map; ///< Demand map.
std::vector<DemandAnnotation> demand_annotation_store; ///< Demand annotation store.
DynUniformArenaAllocator path_allocator; ///< Arena allocator used for paths
/**
@@ -96,18 +108,6 @@ public:
AnnoEdge(EdgeAnnotation &anno) :
anno(anno) {}
/**
* Get the transport demand between end the points of the edge.
* @return Demand.
*/
uint Demand() const { return this->anno.demand; }
/**
* Get the transport demand that hasn't been satisfied by flows, yet.
* @return Unsatisfied demand.
*/
uint UnsatisfiedDemand() const { return this->anno.unsatisfied_demand; }
/**
* Get the total flow on the edge.
* @return Flow.
@@ -129,26 +129,6 @@ public:
assert(flow <= this->anno.flow);
this->anno.flow -= flow;
}
/**
* Add some (not yet satisfied) demand.
* @param demand Demand to be added.
*/
void AddDemand(uint demand)
{
this->anno.demand += demand;
this->anno.unsatisfied_demand += demand;
}
/**
* Satisfy some demand.
* @param demand Demand to be satisfied.
*/
void SatisfyDemand(uint demand)
{
assert(demand <= this->anno.unsatisfied_demand);
this->anno.unsatisfied_demand -= demand;
}
};
/**
@@ -237,13 +217,11 @@ public:
/**
* Deliver some supply, adding demand to the respective edge.
* @param to Destination for supply.
* @param amount Amount of supply to be delivered.
*/
void DeliverSupply(NodeID to, uint amount)
void DeliverSupply(uint amount)
{
this->node_anno.undelivered_supply -= amount;
(*this)[to].AddDemand(amount);
}
/**
@@ -254,6 +232,16 @@ public:
{
this->node_anno.received_demand += amount;
}
span<DemandAnnotation> GetDemandAnnotations() const
{
return this->node_anno.demands;
}
void SetDemandAnnotations(span<DemandAnnotation> demands)
{
this->node_anno.demands = demands;
}
};
/**

1
src/linkgraph/linkgraphjob_base.h
View File

@@ -17,5 +17,6 @@
typedef LinkGraphJob::Node Node;
typedef LinkGraphJob::Edge Edge;
typedef LinkGraphJob::AnnoEdge AnnoEdge;
typedef LinkGraphJob::DemandAnnotation DemandAnnotation;
#endif /* LINKGRAPHJOB_BASE_H */

46
src/linkgraph/mcf.cpp
View File

@@ -391,20 +391,20 @@ void MultiCommodityFlow::CleanupPaths(NodeID source_id, PathVector &paths)
/**
* Push flow along a path and update the unsatisfied_demand of the associated
* edge.
* @param edge Edge whose ends the path connects.
* @param anno Distance annotation whose ends the path connects.
* @param path End of the path the flow should be pushed on.
* @param min_step_size Minimum flow size.
* @param accuracy Accuracy of the calculation.
* @param max_saturation If < UINT_MAX only push flow up to the given
* saturation, otherwise the path can be "overloaded".
*/
uint MultiCommodityFlow::PushFlow(AnnoEdge &edge, Path *path, uint min_step_size, uint accuracy,
uint MultiCommodityFlow::PushFlow(DemandAnnotation &anno, Path *path, uint min_step_size, uint accuracy,
uint max_saturation)
{
assert(edge.UnsatisfiedDemand() > 0);
uint flow = std::min(std::max(edge.Demand() / accuracy, min_step_size), edge.UnsatisfiedDemand());
dbg_assert(anno.unsatisfied_demand > 0);
uint flow = std::min(std::max(anno.demand / accuracy, min_step_size), anno.unsatisfied_demand);
flow = path->AddFlow(flow, this->job, max_saturation);
edge.SatisfyDemand(flow);
anno.unsatisfied_demand -= flow;
return flow;
}
@@ -571,10 +571,10 @@ MCF1stPass::MCF1stPass(LinkGraphJob &job) : MultiCommodityFlow(job)
uint64 total_demand = 0;
uint demand_count = 0;
for (NodeID source = 0; source < size; ++source) {
for (NodeID dest = 0; dest < size; ++dest) {
AnnoEdge edge = job[source][dest];
if (edge.UnsatisfiedDemand() > 0) {
total_demand += edge.UnsatisfiedDemand();
const Node &node = job[source];
for (const DemandAnnotation &anno : node.GetDemandAnnotations()) {
if (anno.unsatisfied_demand > 0) {
total_demand += anno.unsatisfied_demand;
demand_count++;
}
}
@@ -593,24 +593,24 @@ MCF1stPass::MCF1stPass(LinkGraphJob &job) : MultiCommodityFlow(job)
this->Dijkstra<DistanceAnnotation, GraphEdgeIterator>(source, paths);
bool source_demand_left = false;
for (NodeID dest = 0; dest < size; ++dest) {
AnnoEdge edge = job[source][dest];
if (edge.UnsatisfiedDemand() > 0) {
for (DemandAnnotation &anno : job[source].GetDemandAnnotations()) {
NodeID dest = anno.dest;
if (anno.unsatisfied_demand > 0) {
Path *path = paths[dest];
assert(path != nullptr);
/* Generally only allow paths that don't exceed the
* available capacity. But if no demand has been assigned
* yet, make an exception and allow any valid path *once*. */
if (path->GetFreeCapacity() > 0 && this->PushFlow(edge, path,
if (path->GetFreeCapacity() > 0 && this->PushFlow(anno, path,
min_step_size, accuracy, this->max_saturation) > 0) {
/* If a path has been found there is a chance we can
* find more. */
more_loops = more_loops || (edge.UnsatisfiedDemand() > 0);
} else if (edge.UnsatisfiedDemand() == edge.Demand() &&
more_loops = more_loops || (anno.unsatisfied_demand > 0);
} else if (anno.unsatisfied_demand == anno.demand &&
path->GetFreeCapacity() > INT_MIN) {
this->PushFlow(edge, path, min_step_size, accuracy, UINT_MAX);
this->PushFlow(anno, path, min_step_size, accuracy, UINT_MAX);
}
if (edge.UnsatisfiedDemand() > 0) source_demand_left = true;
if (anno.unsatisfied_demand > 0) source_demand_left = true;
}
}
if (!source_demand_left) finished_sources[source] = true;
@@ -640,12 +640,12 @@ MCF2ndPass::MCF2ndPass(LinkGraphJob &job) : MultiCommodityFlow(job)
this->Dijkstra<CapacityAnnotation, FlowEdgeIterator>(source, paths);
bool source_demand_left = false;
for (NodeID dest = 0; dest < size; ++dest) {
AnnoEdge edge = this->job[source][dest];
Path *path = paths[dest];
if (edge.UnsatisfiedDemand() > 0 && path->GetFreeCapacity() > INT_MIN) {
this->PushFlow(edge, path, 1, accuracy, UINT_MAX);
if (edge.UnsatisfiedDemand() > 0) {
for (DemandAnnotation &anno : this->job[source].GetDemandAnnotations()) {
if (anno.unsatisfied_demand == 0) continue;
Path *path = paths[anno.dest];
if (path->GetFreeCapacity() > INT_MIN) {
this->PushFlow(anno, path, 1, accuracy, UINT_MAX);
if (anno.unsatisfied_demand > 0) {
demand_left = true;
source_demand_left = true;
}

2
src/linkgraph/mcf.h
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@@ -24,7 +24,7 @@ protected:
template<class Tannotation, class Tedge_iterator>
void Dijkstra(NodeID from, PathVector &paths);
uint PushFlow(AnnoEdge &edge, Path *path, uint min_step_size, uint accuracy, uint max_saturation);
uint PushFlow(DemandAnnotation &anno, Path *path, uint min_step_size, uint accuracy, uint max_saturation);
void CleanupPaths(NodeID source, PathVector &paths);