(svn r25355) -Add: demand handler for link graph

4 files changed, 344 insertions, 1 deletions

diff --git a/src/linkgraph/demands.cpp b/src/linkgraph/demands.cpp
new file mode 100644
index 000000000..87426326a
--- /dev/null
+++ b/src/linkgraph/demands.cpp
@@ -0,0 +1,298 @@
+/** @file demands.cpp Definition of demand calculating link graph handler. */
+
+#include "../stdafx.h"
+#include "demands.h"
+#include <list>
+
+typedef std::list<NodeID> NodeList;
+
+/**
+ * Scale various things according to symmetric/asymmetric distribution.
+ */
+class Scaler {
+public:
+	/**
+	 * Constructor.
+	 */
+	Scaler() : demand_per_node(0) {}
+
+	void SetDemands(LinkGraphJob &job, NodeID from, NodeID to, uint demand_forw);
+
+protected:
+	uint demand_per_node; ///< Mean demand associated with each node.
+};
+
+/**
+ * Scaler for symmetric distribution.
+ */
+class SymmetricScaler : public Scaler {
+public:
+	/**
+	 * Constructor.
+	 * @param mod_size Size modifier to be used. Determines how much demands
+	 *                 increase with the supply of the remote station.
+	 */
+	inline SymmetricScaler(uint mod_size) : mod_size(mod_size), supply_sum(0)
+	{}
+
+	/**
+	 * Count a node's supply into the sum of supplies.
+	 * @param node Node.
+	 */
+	inline void AddNode(const Node &node)
+	{
+		this->supply_sum += node.Supply();
+	}
+
+	/**
+	 * Calculate the mean demand per node using the sum of supplies.
+	 * @param num_demands Number of accepting nodes.
+	 */
+	inline void SetDemandPerNode(uint num_demands)
+	{
+		this->demand_per_node = max(this->supply_sum / num_demands, 1U);
+	}
+
+	/**
+	 * Get the effective supply of one node towards another one. In symmetric
+	 * distribution the supply of the other node is weighed in.
+	 * @param from The supplying node.
+	 * @param to The receiving node.
+	 * @return Effective supply.
+	 */
+	inline uint EffectiveSupply(const Node &from, const Node &to)
+	{
+		return max(from.Supply() * max(1U, to.Supply()) * this->mod_size / 100 / this->demand_per_node, 1U);
+	}
+
+	/**
+	 * Check if there is any acceptance left for this node. In symmetric distribution
+	 * nodes only accept anything if they also supply something. So if
+	 * undelivered_supply == 0 at the node there isn't any demand left either.
+	 * @param to Node to be checked.
+	 * @return If demand is left.
+	 */
+	inline bool HasDemandLeft(const Node &to)
+	{
+		return (to.Supply() == 0 || to.UndeliveredSupply() > 0) && to.Demand() > 0;
+	}
+
+	void SetDemands(LinkGraphJob &job, NodeID from, NodeID to, uint demand_forw);
+
+private:
+	uint mod_size;   ///< Size modifier. Determines how much demands increase with the supply of the remote station.
+	uint supply_sum; ///< Sum of all supplies in the component.
+};
+
+/**
+ * A scaler for asymmetric distribution.
+ */
+class AsymmetricScaler : public Scaler {
+public:
+	/**
+	 * Constructor.
+	 */
+	inline AsymmetricScaler() : demand_sum(0) {}
+
+	/**
+	 * Count a node's demand into the sum of demands.
+	 * @param node The node to be counted.
+	 */
+	inline void AddNode(const Node &node)
+	{
+		this->demand_sum += node.Demand();
+	}
+
+	/**
+	 * Calculate the mean demand per node using the sum of demands.
+	 * @param num_demands Number of accepting nodes.
+	 */
+	inline void SetDemandPerNode(uint num_demands)
+	{
+		this->demand_per_node = max(this->demand_sum / num_demands, (uint)1);
+	}
+
+	/**
+	 * Get the effective supply of one node towards another one. In asymmetric
+	 * distribution the demand of the other node is weighed in.
+	 * @param from The supplying node.
+	 * @param to The receiving node.
+	 */
+	inline uint EffectiveSupply(const Node &from, const Node &to)
+	{
+		return max(from.Supply() * to.Demand() / this->demand_per_node, (uint)1);
+	}
+
+	/**
+	 * Check if there is any acceptance left for this node. In asymmetric distribution
+	 * nodes always accept as long as their demand > 0.
+	 * @param to The node to be checked.
+	 * @param to_anno Unused.
+	 */
+	inline bool HasDemandLeft(const Node &to) { return to.Demand() > 0; }
+
+private:
+	uint demand_sum; ///< Sum of all demands in the component.
+};
+
+/**
+ * Set the demands between two nodes using the given base demand. In symmetric mode
+ * this sets demands in both directions.
+ * @param job The link graph job.
+ * @param from_id The supplying node.
+ * @þaram to_id The receiving node.
+ * @param demand_forw Demand calculated for the "forward" direction.
+ */
+void SymmetricScaler::SetDemands(LinkGraphJob &job, NodeID from_id, NodeID to_id, uint demand_forw)
+{
+	if (job[from_id].Demand() > 0) {
+		uint demand_back = demand_forw * this->mod_size / 100;
+		uint undelivered = job[to_id].UndeliveredSupply();
+		if (demand_back > undelivered) {
+			demand_back = undelivered;
+			demand_forw = max(1U, demand_back * 100 / this->mod_size);
+		}
+		this->Scaler::SetDemands(job, to_id, from_id, demand_back);
+	}
+
+	this->Scaler::SetDemands(job, from_id, to_id, demand_forw);
+}
+
+/**
+ * Set the demands between two nodes using the given base demand. In asymmetric mode
+ * this only sets demand in the "forward" direction.
+ * @param job The link graph job.
+ * @param from_id The supplying node.
+ * @þaram to_id The receiving node.
+ * @param demand_forw Demand calculated for the "forward" direction.
+ */
+inline void Scaler::SetDemands(LinkGraphJob &job, NodeID from_id, NodeID to_id, uint demand_forw)
+{
+	job[from_id].DeliverSupply(to_id, demand_forw);
+}
+
+/**
+ * Do the actual demand calculation, called from constructor.
+ * @param job Job to calculate the demands for.
+ * @tparam Tscaler Scaler to be used for scaling demands.
+ */
+template<class Tscaler>
+void DemandCalculator::CalcDemand(LinkGraphJob &job, Tscaler scaler)
+{
+	NodeList supplies;
+	NodeList demands;
+	uint num_supplies = 0;
+	uint num_demands = 0;
+
+	for (NodeID node = 0; node < job.Size(); node++) {
+		scaler.AddNode(job[node]);
+		if (job[node].Supply() > 0) {
+			supplies.push_back(node);
+			num_supplies++;
+		}
+		if (job[node].Demand() > 0) {
+			demands.push_back(node);
+			num_demands++;
+		}
+	}
+
+	if (num_supplies == 0 || num_demands == 0) return;
+
+	/* Mean acceptance attributed to each node. If the distribution is
+	 * symmetric this is relative to remote supply, otherwise it is
+	 * relative to remote demand. */
+	scaler.SetDemandPerNode(num_demands);
+	uint chance = 0;
+
+	while (!supplies.empty() && !demands.empty()) {
+		NodeID from_id = supplies.front();
+		supplies.pop_front();
+
+		for (uint i = 0; i < num_demands; ++i) {
+			assert(!demands.empty());
+			NodeID to_id = demands.front();
+			demands.pop_front();
+			if (from_id == to_id) {
+				/* Only one node with supply and demand left */
+				if (demands.empty() && supplies.empty()) return;
+
+				demands.push_back(to_id);
+				continue;
+			}
+
+			int32 supply = scaler.EffectiveSupply(job[from_id], job[to_id]);
+			assert(supply > 0);
+
+			/* Scale the distance by mod_dist around max_distance */
+			int32 distance = this->max_distance - (this->max_distance -
+					(int32)job[from_id][to_id].Distance()) * this->mod_dist / 100;
+
+			/* Scale the accuracy by distance around accuracy / 2 */
+			int32 divisor = this->accuracy * (this->mod_dist - 50) / 100 +
+					this->accuracy * distance / this->max_distance + 1;
+
+			assert(divisor > 0);
+
+			uint demand_forw = 0;
+			if (divisor <= supply) {
+				/* At first only distribute demand if
+				 * effective supply / accuracy divisor >= 1
+				 * Others are too small or too far away to be considered. */
+				demand_forw = supply / divisor;
+			} else if (++chance > this->accuracy * num_demands * num_supplies) {
+				/* After some trying, if there is still supply left, distribute
+				 * demand also to other nodes. */
+				demand_forw = 1;
+			}
+
+			demand_forw = min(demand_forw, job[from_id].UndeliveredSupply());
+
+			scaler.SetDemands(job, from_id, to_id, demand_forw);
+
+			if (scaler.HasDemandLeft(job[to_id])) {
+				demands.push_back(to_id);
+			} else {
+				num_demands--;
+			}
+
+			if (job[from_id].UndeliveredSupply() == 0) break;
+		}
+
+		if (job[from_id].UndeliveredSupply() != 0) {
+			supplies.push_back(from_id);
+		} else {
+			num_supplies--;
+		}
+	}
+}
+
+/**
+ * Create the DemandCalculator and immediately do the calculation.
+ * @param job Job to calculate the demands for.
+ */
+DemandCalculator::DemandCalculator(LinkGraphJob &job) :
+	max_distance(MapSizeX() + MapSizeY() - 2)
+{
+	const LinkGraphSettings &settings = job.Settings();
+	CargoID cargo = job.Cargo();
+
+	this->accuracy = settings.accuracy;
+	this->mod_dist = settings.demand_distance;
+	if (this->mod_dist > 100) {
+		/* Increase effect of mod_dist > 100 */
+		int over100 = this->mod_dist - 100;
+		this->mod_dist = 100 + over100 * over100;
+	}
+
+	switch (settings.GetDistributionType(cargo)) {
+		case DT_SYMMETRIC:
+			this->CalcDemand<SymmetricScaler>(job, SymmetricScaler(settings.demand_size));
+			break;
+		case DT_ASYMMETRIC:
+			this->CalcDemand<AsymmetricScaler>(job, AsymmetricScaler());
+			break;
+		default:
+			/* Nothing to do. */
+			break;
+	}
+}
diff --git a/src/linkgraph/demands.h b/src/linkgraph/demands.h
new file mode 100644
index 000000000..c3d9dc7cd
--- /dev/null
+++ b/src/linkgraph/demands.h
@@ -0,0 +1,43 @@
+/** @file demands.h Declaration of demand calculating link graph handler. */
+
+#ifndef DEMANDS_H
+#define DEMANDS_H
+
+#include "linkgraphjob_base.h"
+
+/**
+ * Calculate the demands. This class has a state, but is recreated for each
+ * call to of DemandHandler::Run.
+ */
+class DemandCalculator {
+public:
+	DemandCalculator(LinkGraphJob &job);
+
+private:
+	int32 max_distance; ///< Maximum distance possible on the map.
+	int32 mod_dist;     ///< Distance modifier, determines how much demands decrease with distance.
+	int32 accuracy;     ///< Accuracy of the calculation.
+
+	template<class Tscaler>
+	void CalcDemand(LinkGraphJob &job, Tscaler scaler);
+};
+
+/**
+ * Stateless, thread safe demand hander. Doesn't do anything but call DemandCalculator.
+ */
+class DemandHandler : public ComponentHandler {
+public:
+
+	/**
+	 * Call the demand calculator on the given component.
+	 * @param graph Component to calculate the demands for.
+	 */
+	virtual void Run(LinkGraphJob &job) const { DemandCalculator c(job); }
+
+	/**
+	 * Virtual destructor has to be defined because of virtual Run().
+	 */
+	virtual ~DemandHandler() {}
+};
+
+#endif /* DEMANDS_H */
diff --git a/src/linkgraph/linkgraphschedule.cpp b/src/linkgraph/linkgraphschedule.cpp
index 31a837ad1..b3e512506 100644
--- a/src/linkgraph/linkgraphschedule.cpp
+++ b/src/linkgraph/linkgraphschedule.cpp
@@ -12,6 +12,7 @@
 #include "../stdafx.h"
 #include "linkgraphschedule.h"
 #include "init.h"
+#include "demands.h"
 
 /**
  * Spawn a thread if possible and run the link graph job in the thread. If
@@ -128,6 +129,7 @@ void LinkGraphSchedule::SpawnAll()
 LinkGraphSchedule::LinkGraphSchedule()
 {
 	this->handlers[0] = new InitHandler;
+	this->handlers[1] = new DemandHandler;
 }
 
 /**
diff --git a/src/linkgraph/linkgraphschedule.h b/src/linkgraph/linkgraphschedule.h
index 3b71f2954..32e0dc6f4 100644
--- a/src/linkgraph/linkgraphschedule.h
+++ b/src/linkgraph/linkgraphschedule.h
@@ -44,7 +44,7 @@ private:
 	friend const SaveLoad *GetLinkGraphScheduleDesc();
 
 protected:
-	ComponentHandler *handlers[1]; ///< Handlers to be run for each job.
+	ComponentHandler *handlers[2]; ///< Handlers to be run for each job.
 	GraphList schedule;            ///< Queue for new jobs.
 	JobList running;               ///< Currently running jobs.