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(svn r25905) -Codechange: A more robust way of detecting loops during order prediction.

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pull/155/head
fonsinchen 11 years ago
parent 8ef95222c9
commit ca0486e410
2 changed files with 70 additions and 33 deletions
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76
src/linkgraph/refresh.cpp
Unescape Escape View File

@ -26,28 +26,48 @@
/* If there are no orders we can't predict anything.*/
if (v->orders.list == NULL) return;
LinkRefresher refresher(v);
/* Make sure the first order is a useful order. */
const Order *first = v->orders.list->GetNextDecisionNode(v->GetOrder(v->cur_implicit_order_index), 0);
if (first == NULL) return;
HopSet seen_hops;
LinkRefresher refresher(v, &seen_hops);
if (refresher.first == NULL) return;
refresher.RefreshLinks(refresher.first, refresher.first, v->last_loading_station != INVALID_STATION ? 1 << HAS_CARGO : 0);
refresher.RefreshLinks(first, first, v->last_loading_station != INVALID_STATION ? 1 << HAS_CARGO : 0);
}
/**
* Comparison operator to allow hops to be used in a std::set.
* @param other Other hop to be compared with.
* @return If this hop is "smaller" than the other (defined by from, to and cargo in this order).
*/
bool LinkRefresher::Hop::operator<(const Hop &other) const
{
if (this->from < other.from) {
return true;
} else if (this->from > other.from) {
return false;
}
if (this->to < other.to) {
return true;
} else if (this->to > other.to) {
return false;
}
return this->cargo < other.cargo;
}
/**
* Constructor for link refreshing algorithm.
* @param vehicle Vehicle to refresh links for.
*/
LinkRefresher::LinkRefresher(Vehicle *vehicle) : vehicle(vehicle), hops(0)
LinkRefresher::LinkRefresher(Vehicle *vehicle, HopSet *seen_hops) :
vehicle(vehicle), seen_hops(seen_hops), cargo(CT_INVALID)
{
/* Assemble list of capacities and set last loading stations to 0. */
for (Vehicle *v = this->vehicle; v != NULL; v = v->Next()) {
this->refit_capacities.push_back(RefitDesc(v->cargo_type, v->cargo_cap, v->refit_cap));
if (v->refit_cap > 0) this->capacities[v->cargo_type] += v->refit_cap;
}
this->first = this->vehicle->GetOrder(this->vehicle->cur_implicit_order_index);
/* Make sure the first order is a useful order. */
this->first = this->vehicle->orders.list->GetNextDecisionNode(this->first, 0);
}
/**
@ -56,11 +76,11 @@ LinkRefresher::LinkRefresher(Vehicle *vehicle) : vehicle(vehicle), hops(0)
*/
void LinkRefresher::HandleRefit(const Order *next)
{
CargoID new_cid = next->GetRefitCargo();
this->cargo = next->GetRefitCargo();
RefitList::iterator refit_it = this->refit_capacities.begin();
for (Vehicle *v = this->vehicle; v != NULL; v = v->Next()) {
const Engine *e = Engine::Get(v->engine_type);
if (!HasBit(e->info.refit_mask, new_cid)) {
if (!HasBit(e->info.refit_mask, this->cargo)) {
++refit_it;
continue;
}
@ -68,8 +88,8 @@ void LinkRefresher::HandleRefit(const Order *next)
/* Back up the vehicle's cargo type */
CargoID temp_cid = v->cargo_type;
byte temp_subtype = v->cargo_subtype;
v->cargo_type = new_cid;
v->cargo_subtype = GetBestFittingSubType(v, v, new_cid);
v->cargo_type = this->cargo;
v->cargo_subtype = GetBestFittingSubType(v, v, this->cargo);
uint16 mail_capacity = 0;
uint amount = e->DetermineCapacity(v, &mail_capacity);
@ -79,7 +99,7 @@ void LinkRefresher::HandleRefit(const Order *next)
v->cargo_subtype = temp_subtype;
/* Skip on next refit. */
if (new_cid != refit_it->cargo && refit_it->remaining > 0) {
if (this->cargo != refit_it->cargo && refit_it->remaining > 0) {
this->capacities[refit_it->cargo] -= refit_it->remaining;
refit_it->remaining = 0;
} else if (amount < refit_it->remaining) {
@ -87,7 +107,7 @@ void LinkRefresher::HandleRefit(const Order *next)
refit_it->remaining = amount;
}
refit_it->capacity = amount;
refit_it->cargo = new_cid;
refit_it->cargo = this->cargo;
++refit_it;
@ -125,6 +145,7 @@ void LinkRefresher::ResetRefit()
*/
const Order *LinkRefresher::PredictNextOrder(const Order *cur, const Order *next, uint8 flags)
{
int num_hops = 0; // Count hops to catch infinite loops without station or implicit orders.
do {
if (HasBit(flags, USE_NEXT)) {
/* First incrementation has to be skipped if a "real" next hop,
@ -134,25 +155,21 @@ const Order *LinkRefresher::PredictNextOrder(const Order *cur, const Order *next
const Order *skip_to = NULL;
if (next->IsType(OT_CONDITIONAL)) {
skip_to = this->vehicle->orders.list->GetNextDecisionNode(
this->vehicle->orders.list->GetOrderAt(next->GetConditionSkipToOrder()),
this->hops / 2);
this->vehicle->orders.list->GetOrderAt(next->GetConditionSkipToOrder()), num_hops++);
}
/* Reassign next with the following stop. This can be a station or a
* depot. Allow the order list to be walked twice so that we can
* reassign "first" below without afterwards terminating early here. */
* depot.*/
next = this->vehicle->orders.list->GetNextDecisionNode(
this->vehicle->orders.list->GetNext(next), ++this->hops / 2);
this->vehicle->orders.list->GetNext(next), num_hops++);
if (skip_to != NULL) {
/* Make copies of capacity tracking lists. There is potential
* for optimization here. If the vehicle never refits we don't
* need to copy anything. Also, if we've seen the branched link
* before we don't need to branch at all. */
++this->hops;
LinkRefresher branch(*this);
branch.RefreshLinks(cur, skip_to, flags | (cur != skip_to ? 1 << USE_NEXT : 0));
this->hops = branch.hops;
}
}
} while (next != NULL && next->IsType(OT_CONDITIONAL));
@ -216,6 +233,12 @@ void LinkRefresher::RefreshLinks(const Order *cur, const Order *next, uint8 flag
next = this->PredictNextOrder(cur, next, flags);
if (next == NULL) break;
Hop hop(cur->index, next->index, this->cargo);
if (this->seen_hops->find(hop) != this->seen_hops->end()) {
break;
} else {
this->seen_hops->insert(hop);
}
/* Skip resetting and link refreshing if next order won't do anything with cargo. */
if (!next->IsType(OT_GOTO_STATION) && !next->IsType(OT_IMPLICIT)) continue;
@ -236,14 +259,7 @@ void LinkRefresher::RefreshLinks(const Order *cur, const Order *next, uint8 flag
}
/* "cur" is only assigned here if the stop is a station so that
* whenever stats are to be increased two stations can be found.
* However, "first" can be a depot stop. If that is the case
* reassign it to make sure we end up with a station for the last
* link. */
* whenever stats are to be increased two stations can be found. */
cur = next;
if (cur == this->first) break;
if (!this->first->IsType(OT_GOTO_STATION) && !this->first->IsType(OT_IMPLICIT)) {
this->first = cur;
}
}
}

27
src/linkgraph/refresh.h
Unescape Escape View File

@ -16,6 +16,7 @@
#include "../vehicle_base.h"
#include <list>
#include <map>
#include <set>
/**
* Utility to refresh links a consist will visit.
@ -47,15 +48,35 @@ protected:
cargo(cargo), capacity(capacity), remaining(remaining) {}
};
/**
* A hop the refresh algorithm might evaluate. If the same hop is seen again
* the evaluation is stopped. This of course is a fairly simple heuristic.
* Sequences of refit orders can produce vehicles with all kinds of
* different cargoes and remembering only one can lead to early termination
* of the algorithm. However, as the order language is Turing complete, we
* are facing the halting problem here. At some point we have to draw the
* line.
*/
struct Hop {
OrderID from; ///< Last order where vehicle could interact with cargo or absolute first order.
OrderID to; ///< Next order to be processed.
CargoID cargo; ///< Cargo the consist is probably carrying or CT_INVALID if unknown.
Hop() {NOT_REACHED();}
Hop(OrderID from, OrderID to, CargoID cargo) : from(from), to(to), cargo(cargo) {}
bool operator<(const Hop &other) const;
};
typedef std::list<RefitDesc> RefitList;
typedef std::map<CargoID, uint> CapacitiesMap;
typedef std::set<Hop> HopSet;
Vehicle *vehicle; ///< Vehicle for which the links should be refreshed.
const Order *first; ///< Order to be checked first. If this is encountered again the refreshing is considered finished.
CapacitiesMap capacities; ///< Current added capacities per cargo ID in the consist.
RefitList refit_capacities; ///< Current state of capacity remaining from previous refits versus overall capacity per vehicle in the consist.
uint hops; ///< Number of hops already used up. If more than two times the number of orders in the list have been checked refreshing is stopped.
LinkRefresher(Vehicle *v);
HopSet *seen_hops; ///< Hops already seen. If the same hop is seen twice we stop the algorithm. This is shared between all Refreshers of the same run.
CargoID cargo; ///< Cargo given in last refit order.
LinkRefresher(Vehicle *v, HopSet *seen_hops);
void HandleRefit(const Order *next);
void ResetRefit();

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