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-rw-r--r--src/station_base.h83
-rw-r--r--src/station_cmd.cpp181
2 files changed, 264 insertions, 0 deletions
diff --git a/src/station_base.h b/src/station_base.h
index 974caa063..200d97a97 100644
--- a/src/station_base.h
+++ b/src/station_base.h
@@ -12,12 +12,14 @@
#ifndef STATION_BASE_H
#define STATION_BASE_H
+#include "core/random_func.hpp"
#include "base_station_base.h"
#include "newgrf_airport.h"
#include "cargopacket.h"
#include "industry_type.h"
#include "linkgraph/linkgraph_type.h"
#include "newgrf_storage.h"
+#include <map>
typedef Pool<BaseStation, StationID, 32, 64000> StationPool;
extern StationPool _station_pool;
@@ -25,6 +27,87 @@ extern StationPool _station_pool;
static const byte INITIAL_STATION_RATING = 175;
/**
+ * Flow statistics telling how much flow should be sent along a link. This is
+ * done by creating "flow shares" and using std::map's upper_bound() method to
+ * look them up with a random number. A flow share is the difference between a
+ * key in a map and the previous key. So one key in the map doesn't actually
+ * mean anything by itself.
+ */
+class FlowStat {
+public:
+ typedef std::map<uint32, StationID> SharesMap;
+
+ /**
+ * Invalid constructor. This can't be called as a FlowStat must not be
+ * empty. However, the constructor must be defined and reachable for
+ * FlwoStat to be used in a std::map.
+ */
+ inline FlowStat() {NOT_REACHED();}
+
+ /**
+ * Create a FlowStat with an initial entry.
+ * @param st Station the initial entry refers to.
+ * @param flow Amount of flow for the initial entry.
+ */
+ inline FlowStat(StationID st, uint flow)
+ {
+ assert(flow > 0);
+ this->shares[flow] = st;
+ }
+
+ /**
+ * Add some flow to the end of the shares map. Only do that if you know
+ * that the station isn't in the map yet. Anything else may lead to
+ * inconsistencies.
+ * @param st Remote station.
+ * @param flow Amount of flow to be added.
+ */
+ inline void AppendShare(StationID st, uint flow)
+ {
+ assert(flow > 0);
+ this->shares[(--this->shares.end())->first + flow] = st;
+ }
+
+ uint GetShare(StationID st) const;
+
+ void ChangeShare(StationID st, int flow);
+
+ /**
+ * Get the actual shares as a const pointer so that they can be iterated
+ * over.
+ * @return Actual shares.
+ */
+ inline const SharesMap *GetShares() const { return &this->shares; }
+
+ /**
+ * Get a station a package can be routed to. This done by drawing a
+ * random number between 0 and sum_shares and then looking that up in
+ * the map with lower_bound. So each share gets selected with a
+ * probability dependent on its flow.
+ * @return A station ID from the shares map.
+ */
+ inline StationID GetVia() const
+ {
+ assert(!this->shares.empty());
+ return this->shares.upper_bound(RandomRange((--this->shares.end())->first - 1))->second;
+ }
+
+ StationID GetVia(StationID excluded, StationID excluded2 = INVALID_STATION) const;
+
+private:
+ SharesMap shares; ///< Shares of flow to be sent via specified station (or consumed locally).
+};
+
+/** Flow descriptions by origin stations. */
+class FlowStatMap : public std::map<StationID, FlowStat> {
+public:
+ void AddFlow(StationID origin, StationID via, uint amount);
+ void PassOnFlow(StationID origin, StationID via, uint amount);
+ void DeleteFlows(StationID via);
+ void FinalizeLocalConsumption(StationID self);
+};
+
+/**
* Stores station stats for a single cargo.
*/
struct GoodsEntry {
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
index 03003a518..1dad5d292 100644
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -3979,6 +3979,187 @@ static CommandCost TerraformTile_Station(TileIndex tile, DoCommandFlag flags, in
return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
}
+/**
+ * Get flow for a station.
+ * @param st Station to get flow for.
+ * @return Flow for st.
+ */
+uint FlowStat::GetShare(StationID st) const
+{
+ uint32 prev = 0;
+ for (SharesMap::const_iterator it = this->shares.begin(); it != this->shares.end(); ++it) {
+ if (it->second == st) {
+ return it->first - prev;
+ } else {
+ prev = it->first;
+ }
+ }
+ return 0;
+}
+
+/**
+ * Get a station a package can be routed to, but exclude the given one.
+ * @param excluded StationID not to be selected.
+ * @return A station ID from the shares map.
+ */
+StationID FlowStat::GetVia(StationID excluded, StationID excluded2) const
+{
+ assert(!this->shares.empty());
+ uint max = (--this->shares.end())->first - 1;
+ SharesMap::const_iterator it = this->shares.upper_bound(RandomRange(max));
+ assert(it != this->shares.end());
+ if (it->second != excluded && it->second != excluded2) return it->second;
+
+ /* We've hit one of the excluded stations.
+ * Draw another share, from outside its range. */
+
+ uint end = it->first;
+ uint begin = (it == this->shares.begin() ? 0 : (--it)->first);
+ uint interval = end - begin;
+ if (interval > max) return INVALID_STATION; // Only one station in the map.
+ uint new_max = max - interval;
+ uint rand = RandomRange(new_max);
+ SharesMap::const_iterator it2 = (rand < begin) ? this->shares.upper_bound(rand) :
+ this->shares.upper_bound(rand + interval);
+ assert(it2 != this->shares.end());
+ if (it2->second != excluded && it2->second != excluded2) return it2->second;
+
+ /* We've hit the second excluded station.
+ * Same as before, only a bit more complicated. */
+
+ uint end2 = it2->first;
+ uint begin2 = (it2 == this->shares.begin() ? 0 : (--it2)->first);
+ uint interval2 = end2 - begin2;
+ if (interval2 > new_max) return INVALID_STATION; // Only the two excluded stations in the map.
+ new_max -= interval2;
+ if (begin > begin2) {
+ Swap(begin, begin2);
+ Swap(end, end2);
+ Swap(interval, interval2);
+ }
+ rand = RandomRange(new_max);
+ SharesMap::const_iterator it3 = this->shares.end();
+ if (rand < begin) {
+ it3 = this->shares.upper_bound(rand);
+ } else if (rand < begin2 - interval) {
+ it3 = this->shares.upper_bound(rand + interval);
+ } else {
+ it3 = this->shares.upper_bound(rand + interval + interval2);
+ }
+ assert(it3 != this->shares.end());
+ return it3->second;
+
+}
+
+/**
+ * Change share for specified station. By specifing INT_MIN as parameter you
+ * can erase a share.
+ * @param st Next Hop to be removed.
+ * @param flow Share to be added or removed.
+ */
+void FlowStat::ChangeShare(StationID st, int flow)
+{
+ /* We assert only before changing as afterwards the shares can actually
+ * be empty. In that case the whole flow stat must be deleted then. */
+ assert(!this->shares.empty());
+
+ int32 added_shares = 0;
+ uint32 last_share = 0;
+ SharesMap new_shares;
+ for (SharesMap::iterator it(this->shares.begin()); it != this->shares.end(); ++it) {
+ if (it->second == st) {
+ uint share = it->first - last_share;
+ int change = flow - added_shares;
+ uint new_share = (change < 0 && (uint)(-change) > share) ? 0 : share + change;
+ added_shares -= share;
+ added_shares += new_share;
+ if (new_share > 0) {
+ new_shares[it->first + added_shares] = it->second;
+ }
+ } else {
+ new_shares[it->first + added_shares] = it->second;
+ }
+ last_share = it->first;
+ }
+ if (flow > added_shares) {
+ new_shares[last_share + flow - added_shares] = st;
+ }
+ this->shares.swap(new_shares);
+}
+
+/**
+ * Add some flow from "origin", going via "via".
+ * @param origin Origin of the flow.
+ * @param via Next hop.
+ * @param flow Amount of flow to be added.
+ */
+void FlowStatMap::AddFlow(StationID origin, StationID via, uint flow)
+{
+ FlowStatMap::iterator origin_it = this->find(origin);
+ if (origin_it == this->end()) {
+ this->insert(std::make_pair(origin, FlowStat(via, flow)));
+ } else {
+ origin_it->second.ChangeShare(via, flow);
+ assert(!origin_it->second.GetShares()->empty());
+ }
+}
+
+/**
+ * Pass on some flow, remembering it as invalid, for later subtraction from
+ * locally consumed flow. This is necessary because we can't have negative
+ * flows and we don't want to sort the flows before adding them up.
+ * @param origin Origin of the flow.
+ * @param via Next hop.
+ * @param flow Amount of flow to be passed.
+ */
+void FlowStatMap::PassOnFlow(StationID origin, StationID via, uint flow)
+{
+ FlowStatMap::iterator prev_it = this->find(origin);
+ if (prev_it == this->end()) {
+ FlowStat fs(via, flow);
+ fs.AppendShare(INVALID_STATION, flow);
+ this->insert(std::make_pair(origin, fs));
+ } else {
+ prev_it->second.ChangeShare(via, flow);
+ prev_it->second.ChangeShare(INVALID_STATION, flow);
+ assert(!prev_it->second.GetShares()->empty());
+ }
+}
+
+/**
+ * Subtract invalid flows from locally consumed flow.
+ * @param self ID of own station.
+ */
+void FlowStatMap::FinalizeLocalConsumption(StationID self)
+{
+ for (FlowStatMap::iterator i = this->begin(); i != this->end(); ++i) {
+ FlowStat &fs = i->second;
+ uint local = fs.GetShare(INVALID_STATION);
+ fs.ChangeShare(self, -local);
+ fs.ChangeShare(INVALID_STATION, -local);
+
+ /* If the local share is used up there must be a share for some
+ * remote station. */
+ assert(!fs.GetShares()->empty());
+ }
+}
+
+/**
+ * Delete all flows at a station for specific cargo and destination.
+ * @param via Remote station of flows to be deleted.
+ */
+void FlowStatMap::DeleteFlows(StationID via)
+{
+ for (FlowStatMap::iterator f_it = this->begin(); f_it != this->end();) {
+ FlowStat &s_flows = f_it->second;
+ s_flows.ChangeShare(via, INT_MIN);
+ if (s_flows.GetShares()->empty()) {
+ this->erase(f_it++);
+ } else {
+ ++f_it;
+ }
+ }
+}
extern const TileTypeProcs _tile_type_station_procs = {
DrawTile_Station, // draw_tile_proc