source/libr2c2/trainrouteplanner.cpp

   1 #include <msp/core/maputils.h>
   2 #include <msp/time/utils.h>
   3 #include "catalogue.h"
   4 #include "layout.h"
   5 #include "route.h"
   6 #include "train.h"
   7 #include "trainroutemetric.h"
   8 #include "trainrouteplanner.h"
   9 #include "trainrouter.h"
  10 #include "vehicle.h"
  11
  12 using namespace std;
  13 using namespace Msp;
  14
  15 namespace R2C2 {
  16
  17 TrainRoutePlanner::TrainRoutePlanner(Layout &layout):
  18         goal(0),
  19         path_switch_bias(15*Time::sec),
  20         timeout(10*Time::sec),
  21         result(PENDING),
  22         thread(0)
  23 {
  24         const map<unsigned, Train *> &trains = layout.get_trains();
  25         for(map<unsigned, Train *>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
  26         {
  27                 TrainRoutingInfo info(*i->second);
  28                 if(!info.waypoints.empty())
  29                         routed_trains.push_back(info);
  30         }
  31 }
  32
  33 TrainRoutePlanner::~TrainRoutePlanner()
  34 {
  35         if(thread)
  36         {
  37                 thread->join();
  38                 delete thread;
  39         }
  40 }
  41
  42 void TrainRoutePlanner::set_timeout(const Time::TimeDelta &t)
  43 {
  44         timeout = t;
  45 }
  46
  47 TrainRoutePlanner::Result TrainRoutePlanner::plan()
  48 {
  49         prepare_plan();
  50         create_plan();
  51         if(result==PENDING)
  52                 finalize_plan();
  53
  54         return result;
  55 }
  56
  57 void TrainRoutePlanner::plan_async()
  58 {
  59         if(thread)
  60                 throw logic_error("already planning");
  61
  62         prepare_plan();
  63         thread = new PlanningThread(*this);
  64 }
  65
  66 TrainRoutePlanner::Result TrainRoutePlanner::check()
  67 {
  68         if(result==PENDING && goal)
  69         {
  70                 if(thread)
  71                 {
  72                         thread->join();
  73                         delete thread;
  74                         thread = 0;
  75                 }
  76                 finalize_plan();
  77         }
  78
  79         return result;
  80 }
  81
  82 const list<Route *> &TrainRoutePlanner::get_routes_for(const Train &train) const
  83 {
  84         return get_train_info(train).routes;
  85 }
  86
  87 const list<TrainRouter::SequencePoint> &TrainRoutePlanner::get_sequence_for(const Train &train) const
  88 {
  89         return get_train_info(train).sequence;
  90 }
  91
  92 const TrainRoutePlanner::TrainRoutingInfo &TrainRoutePlanner::get_train_info(const Train &train) const
  93 {
  94         for(vector<TrainRoutingInfo>::const_iterator i=routed_trains.begin(); i!=routed_trains.end(); ++i)
  95                 if(i->train==&train)
  96                         return *i;
  97
  98         throw key_error(train.get_name());
  99 }
 100
 101 const TrainRoutePlanner::RoutingStep &TrainRoutePlanner::get_step()
 102 {
 103         steps.splice(steps.end(), queue, queue.begin());
 104         return steps.back();
 105 }
 106
 107 void TrainRoutePlanner::prepare_plan()
 108 {
 109         steps.clear();
 110         queue.clear();
 111         goal = 0;
 112         result = PENDING;
 113
 114         queue.push_back(RoutingStep());
 115         RoutingStep &start = queue.back();
 116         for(vector<TrainRoutingInfo>::iterator i=routed_trains.begin(); i!=routed_trains.end(); ++i)
 117                 start.trains.push_back(TrainRoutingState(*i));
 118         start.update_estimate();
 119 }
 120
 121 void TrainRoutePlanner::create_plan()
 122 {
 123         Time::TimeStamp timeout_stamp = Time::now()+timeout;
 124         unsigned count = 0;
 125         while(!queue.empty())
 126         {
 127                 const RoutingStep &step = get_step();
 128                 if(step.is_goal())
 129                 {
 130                         goal = &step;
 131                         return;
 132                 }
 133
 134                 add_steps(step);
 135
 136                 if(++count>=1000)
 137                 {
 138                         if(Time::now()>timeout_stamp)
 139                                 break;
 140                         count = 0;
 141                 }
 142         }
 143
 144         result = FAILED;
 145 }
 146
 147 void TrainRoutePlanner::add_steps(const RoutingStep &step)
 148 {
 149         list<RoutingStep> new_steps;
 150         step.create_successors(new_steps);
 151         if(new_steps.empty())
 152                 return;
 153
 154         new_steps.sort();
 155         if(!queue.empty() && new_steps.front().cost_estimate<queue.front().cost_estimate+path_switch_bias)
 156                 new_steps.front().preferred = true;
 157         queue.merge(new_steps);
 158 }
 159
 160 void TrainRoutePlanner::finalize_plan()
 161 {
 162         for(vector<TrainRoutingInfo>::iterator i=routed_trains.begin(); i!=routed_trains.end(); ++i)
 163         {
 164                 i->routes.clear();
 165                 i->sequence.clear();
 166                 for(unsigned j=0; j<2; ++j)
 167                         i->track_history[j] = 0;
 168         }
 169
 170         map<Track *, TrainRouter::SequencePoint *> sequenced_tracks;
 171         unsigned sequence = steps.size();
 172         for(const RoutingStep *i=goal; i; i=i->prev)
 173                 for(vector<TrainRoutingState>::const_iterator j=i->trains.begin(); j!=i->trains.end(); ++j)
 174                 {
 175                         Track **history = j->info->track_history;
 176                         // Don't process the same track again.
 177                         if(j->track.track()==history[0])
 178                                 continue;
 179
 180                         Route *route = 0;
 181                         bool start_new_route = true;
 182                         if(!j->info->routes.empty())
 183                         {
 184                                 /* If we already have a route and this track or any linked track is
 185                                 in it, start a new one to avoid loops. */
 186                                 route = j->info->routes.front();
 187                                 start_new_route = route->has_track(*j->track);
 188                                 if(!start_new_route)
 189                                 {
 190                                         unsigned nls = j->track->get_n_link_slots();
 191                                         for(unsigned k=0; (!start_new_route && k<nls); ++k)
 192                                         {
 193                                                 Track *link = j->track->get_link(k);
 194                                                 start_new_route = (link && link!=history[0] && route->has_track(*link));
 195                                         }
 196                                 }
 197                         }
 198
 199                         if(start_new_route)
 200                         {
 201                                 route = new Route(j->info->train->get_layout());
 202                                 route->set_name("Router");
 203                                 route->set_temporary(true);
 204                                 /* Have the routes overlap by two tracks to ensure that turnout
 205                                 paths can be deduced. */
 206                                 for(unsigned k=0; (k<2 && history[k]); ++k)
 207                                         route->add_track(*history[k]);
 208                                 j->info->routes.push_front(route);
 209                         }
 210
 211                         route->add_track(*j->track.track());
 212                         history[1] = history[0];
 213                         history[0] = j->track.track();
 214
 215                         bool waitable = j->track.endpoint().paths!=j->track->get_type().get_paths();
 216                         map<Track *, TrainRouter::SequencePoint *>::iterator k = sequenced_tracks.find(j->track.track());
 217                         if(k!=sequenced_tracks.end())
 218                         {
 219                                 // Add a sequence point if another train uses this track afterwards.
 220                                 if(!k->second->preceding_train)
 221                                 {
 222                                         k->second->preceding_train = j->info->train;
 223                                         k->second->sequence_in = sequence;
 224                                 }
 225                                 j->info->sequence.push_front(TrainRouter::SequencePoint(j->track->get_block(), sequence));
 226                                 if(waitable)
 227                                         k->second = &j->info->sequence.front();
 228                                 --sequence;
 229                         }
 230                         else if(waitable)
 231                         {
 232                                 /* Create a sequence point if it's possible to wait and let another
 233                                 train past. */
 234                                 j->info->sequence.push_front(TrainRouter::SequencePoint(j->track->get_block(), sequence));
 235                                 sequenced_tracks[j->track.track()] = &j->info->sequence.front();
 236                                 --sequence;
 237                         }
 238                 }
 239
 240         result = COMPLETE;
 241 }
 242
 243
 244 TrainRoutePlanner::TrainRoutingInfo::TrainRoutingInfo(Train &t):
 245         train(&t),
 246         length(0),
 247         speed(train->get_maximum_speed()),
 248         first_noncritical(train->get_last_critical_block().next().block()),
 249         router(train->get_ai_of_type<TrainRouter>()),
 250         has_duration(false)
 251 {
 252         if(!router)
 253                 return;
 254
 255         if(unsigned n_wps = router->get_n_waypoints())
 256         {
 257                 waypoints.reserve(n_wps),
 258                 metrics.reserve(n_wps);
 259                 for(unsigned i=0; i<n_wps; ++i)
 260                 {
 261                         waypoints.push_back(router->get_waypoint(i));
 262                         metrics.push_back(&router->get_metric(i));
 263                 }
 264                 has_duration = router->get_trip_duration();
 265         }
 266
 267         unsigned n_vehs = train->get_n_vehicles();
 268         for(unsigned i=0; i<n_vehs; ++i)
 269                 length += train->get_vehicle(i).get_type().get_length();
 270
 271         // If no maximum speed is specified, use a sensible default
 272         if(!speed)
 273                 speed = 20*train->get_layout().get_catalogue().get_scale();
 274 }
 275
 276
 277 TrainRoutePlanner::OccupiedTrack::OccupiedTrack(Track &t, unsigned p, OccupiedTrack *n):
 278         track(&t),
 279         path_length(track->get_type().get_path_length(p)),
 280         next(n),
 281         n_tracks(next ? next->n_tracks+1 : 1),
 282         refcount(1)
 283 {
 284         if(next)
 285                 ++next->refcount;
 286 }
 287
 288 TrainRoutePlanner::OccupiedTrack::OccupiedTrack(const OccupiedTrack &other):
 289         track(other.track),
 290         path_length(other.path_length),
 291         next(other.next),
 292         n_tracks(other.n_tracks),
 293         refcount(1)
 294 {
 295         if(next)
 296                 ++next->refcount;
 297 }
 298
 299 TrainRoutePlanner::OccupiedTrack::~OccupiedTrack()
 300 {
 301         if(next && !--next->refcount)
 302                 delete next;
 303 }
 304
 305
 306 TrainRoutePlanner::TrainRoutingState::TrainRoutingState(TrainRoutingInfo &inf):
 307         info(&inf),
 308         critical(true),
 309         occupied_tracks(0),
 310         state(MOVING),
 311         delay(info->router->get_departure_delay()),
 312         duration(info->router->get_trip_duration()),
 313         waypoint(0),
 314         distance_traveled(0),
 315         blocked_by(-1)
 316 {
 317         const Vehicle *veh = &info->train->get_vehicle(0);
 318         // TODO margins
 319         TrackOffsetIter track_and_offs = veh->get_placement().get_position(VehiclePlacement::FRONT_BUFFER);
 320         track = track_and_offs.track_iter();
 321         offset = track_and_offs.offset();
 322         path = track->get_active_path();
 323
 324         while(Vehicle *next = veh->get_link(1))
 325                 veh = next;
 326         track_and_offs = veh->get_placement().get_position(VehiclePlacement::BACK_BUFFER);
 327         back_offset = track_and_offs.offset();
 328
 329         TrackIter iter = track_and_offs.track_iter();
 330         while(1)
 331         {
 332                 occupied_tracks = new OccupiedTrack(*iter, iter->get_active_path(), occupied_tracks);
 333                 if(iter.track()==track.track())
 334                         break;
 335                 iter = iter.next();
 336         }
 337
 338         travel_multiplier = info->metrics[waypoint]->get_travel_multiplier(*track, track.reverse(path).entry());
 339
 340         update_estimate();
 341 }
 342
 343 TrainRoutePlanner::TrainRoutingState::TrainRoutingState(const TrainRoutingState &other):
 344         info(other.info),
 345         track(other.track),
 346         path(other.path),
 347         critical(other.critical),
 348         occupied_tracks(other.occupied_tracks),
 349         offset(other.offset),
 350         back_offset(other.back_offset),
 351         state(other.state),
 352         delay(other.delay),
 353         duration(other.duration),
 354         waypoint(other.waypoint),
 355         travel_multiplier(other.travel_multiplier),
 356         distance_traveled(other.distance_traveled),
 357         remaining_estimate(other.remaining_estimate),
 358         wait_time(other.wait_time),
 359         estimated_wait(other.estimated_wait),
 360         blocked_by(other.blocked_by)
 361 {
 362         ++occupied_tracks->refcount;
 363 }
 364
 365 TrainRoutePlanner::TrainRoutingState::~TrainRoutingState()
 366 {
 367         if(occupied_tracks && !--occupied_tracks->refcount)
 368                 delete occupied_tracks;
 369 }
 370
 371 Time::TimeDelta TrainRoutePlanner::TrainRoutingState::get_time_to_next_track() const
 372 {
 373         return ((occupied_tracks->path_length-offset)/info->speed)*Time::sec+delay+estimated_wait;
 374 }
 375
 376 Time::TimeDelta TrainRoutePlanner::TrainRoutingState::get_time_to_pass(Track &trk) const
 377 {
 378         if(is_occupying(trk))
 379         {
 380                 if(state==ARRIVED && info->has_duration)
 381                         return duration;
 382
 383                 float passed_length = 0;
 384                 for(const OccupiedTrack *occ=occupied_tracks; (occ && occ->track!=&trk); occ=occ->next)
 385                         passed_length += occ->path_length;
 386                 return (max(info->length-passed_length, 0.0f)/info->speed)*Time::sec+delay;
 387         }
 388
 389         for(unsigned wp=waypoint; wp<info->waypoints.size(); ++wp)
 390         {
 391                 float distance = info->metrics[wp]->get_distance_from(trk);
 392                 if(distance>=0 && distance<remaining_estimate)
 393                         return ((remaining_estimate-distance+info->length)/info->speed)*Time::sec+delay;
 394         }
 395
 396         return Time::day;
 397 }
 398
 399 bool TrainRoutePlanner::TrainRoutingState::is_occupying(Track &trk) const
 400 {
 401         if(state==ARRIVED && !duration && info->has_duration)
 402                 return false;
 403
 404         OccupiedTrack *occ = occupied_tracks;
 405         for(unsigned n=occ->n_tracks; n>0; --n, occ=occ->next)
 406                 if(occ->track==&trk)
 407                         return true;
 408         return false;
 409 }
 410
 411 bool TrainRoutePlanner::TrainRoutingState::check_arrival()
 412 {
 413         TrackIter next_track = track.next(path);
 414
 415         // Check if we're about the exit the current waypoint's tracks.
 416         const TrainRouter::Waypoint &wp = info->waypoints[waypoint];
 417         if(wp.chain->has_track(*track) && !wp.chain->has_track(*next_track))
 418                 if(wp.direction==TrackChain::UNSPECIFIED || track==wp.chain->iter_for(*track, wp.direction))
 419                 {
 420                         if(waypoint+1<info->waypoints.size())
 421                                 ++waypoint;
 422                         else
 423                         {
 424                                 state = ARRIVED;
 425                                 return true;
 426                         }
 427                 }
 428
 429         // If we're entering the first non-critical block, clear the critical flag.
 430         if(info->first_noncritical->has_track(*next_track))
 431                 critical = false;
 432
 433         return false;
 434 }
 435
 436 void TrainRoutePlanner::TrainRoutingState::advance(float distance)
 437 {
 438         offset += distance;
 439         back_offset += distance;
 440
 441         // See if the tail end of the train has passed any sensors.
 442         unsigned count_to_free = 0;
 443         unsigned last_sensor_addr = 0;
 444         float distance_after_sensor = 0;
 445         OccupiedTrack *occ = occupied_tracks;
 446         for(unsigned n=occupied_tracks->n_tracks; n>0; --n)
 447         {
 448                 if(unsigned saddr = occ->track->get_sensor_address())
 449                 {
 450                         if(saddr!=last_sensor_addr)
 451                         {
 452                                 count_to_free = 0;
 453                                 distance_after_sensor = 0;
 454                         }
 455                         last_sensor_addr = saddr;
 456                 }
 457
 458                 ++count_to_free;
 459                 distance_after_sensor += occ->path_length;
 460
 461                 occ = occ->next;
 462         }
 463
 464         // Free the last passed sensor and any tracks behind it.
 465         if(count_to_free && back_offset>distance_after_sensor)
 466         {
 467                 back_offset -= distance_after_sensor;
 468                 if(occupied_tracks->refcount>1)
 469                 {
 470                         --occupied_tracks->refcount;
 471                         occupied_tracks = new OccupiedTrack(*occupied_tracks);
 472                 }
 473                 occupied_tracks->n_tracks -= count_to_free;
 474         }
 475
 476         distance_traveled += distance*travel_multiplier;
 477         remaining_estimate -= distance*travel_multiplier;
 478 }
 479
 480 void TrainRoutePlanner::TrainRoutingState::advance(const Time::TimeDelta &dt)
 481 {
 482         if(delay>=dt)
 483         {
 484                 delay -= dt;
 485                 return;
 486         }
 487
 488         float secs = dt/Time::sec;
 489         // There may be some delay remaining.
 490         if(delay)
 491         {
 492                 secs -= delay/Time::sec;
 493                 delay = Time::zero;
 494         }
 495
 496         if(duration)
 497                 duration = max(duration-secs*Time::sec, Time::zero);
 498
 499         if(estimated_wait)
 500                 estimated_wait = max(estimated_wait-secs*Time::sec, Time::zero);
 501
 502         float distance = info->speed*secs;
 503         float remaining_on_track = occupied_tracks->path_length-offset;
 504         if(state==MOVING || distance<remaining_on_track)
 505                 advance(info->speed*secs);
 506         else if(state!=ARRIVED)
 507         {
 508                 if(remaining_on_track>0)
 509                 {
 510                         advance(remaining_on_track);
 511                         wait_time += (secs-remaining_on_track/info->speed)*Time::sec;
 512                 }
 513                 else
 514                         wait_time += secs*Time::sec;
 515         }
 516 }
 517
 518 void TrainRoutePlanner::TrainRoutingState::advance_track(unsigned next_path)
 519 {
 520         float distance = occupied_tracks->path_length-offset;
 521
 522         track = track.next(path);
 523         path = next_path;
 524         occupied_tracks = new OccupiedTrack(*track, path, occupied_tracks);
 525
 526         advance(distance);
 527         offset = 0;
 528         travel_multiplier = info->metrics[waypoint]->get_travel_multiplier(*track, track.reverse(path).entry());
 529 }
 530
 531 void TrainRoutePlanner::TrainRoutingState::set_path(unsigned p)
 532 {
 533         path = p;
 534         OccupiedTrack *next_occ = occupied_tracks->next;
 535         if(!--occupied_tracks->refcount)
 536                 delete occupied_tracks;
 537         occupied_tracks = new OccupiedTrack(*track, path, next_occ);
 538         update_estimate();
 539 }
 540
 541 void TrainRoutePlanner::TrainRoutingState::update_estimate()
 542 {
 543         TrackIter iter = track.reverse(path);
 544         const TrainRouteMetric *metric = info->metrics[waypoint];
 545         remaining_estimate = metric->get_distance_from(*iter, iter.entry());
 546         travel_multiplier = metric->get_travel_multiplier(*iter, iter.entry());
 547         if(remaining_estimate>=0)
 548                 remaining_estimate += (occupied_tracks->path_length-offset)*travel_multiplier;
 549 }
 550
 551 bool TrainRoutePlanner::TrainRoutingState::is_viable() const
 552 {
 553         if(remaining_estimate<0)
 554                 return false;
 555         if(critical && state==BLOCKED)
 556                 return false;
 557         return true;
 558 }
 559
 560
 561 TrainRoutePlanner::RoutingStep::RoutingStep():
 562         preferred(false),
 563         prev(0)
 564 { }
 565
 566 TrainRoutePlanner::RoutingStep::RoutingStep(const RoutingStep *p):
 567         time(p->time),
 568         cost_estimate(p->cost_estimate),
 569         preferred(false),
 570         trains(p->trains),
 571         prev(p)
 572 { }
 573
 574 void TrainRoutePlanner::RoutingStep::create_successors(list<RoutingStep> &new_steps) const
 575 {
 576         RoutingStep next(this);
 577         if(next.update_states() && next.check_deadlocks())
 578                 return;
 579
 580         int train_index = next.find_next_train();
 581         if(train_index<0)
 582                 return;
 583
 584         TrainRoutingState &train = next.trains[train_index];
 585
 586         Time::TimeDelta dt = train.get_time_to_next_track();
 587         next.advance(dt);
 588
 589         /* Check arrival after the train has advanced to the end of its current track
 590         so travel time and occupied tracks will be correct. */
 591         if(train.check_arrival())
 592         {
 593                 new_steps.push_back(next);
 594                 return;
 595         }
 596
 597         if(train.state==MOVING)
 598                 train.advance_track(0);
 599         else
 600         {
 601                 new_steps.push_back(next);
 602                 return;
 603         }
 604
 605         const TrackType::Endpoint &entry_ep = train.track.endpoint();
 606         if(train.critical)
 607         {
 608                 /* Only create a successor step matching the currently set path for a
 609                 critical track. */
 610                 unsigned critical_path = train.track->get_type().coerce_path(train.track.entry(), train.track->get_active_path());
 611                 create_successor(next, train_index, critical_path, new_steps);
 612         }
 613         else
 614         {
 615                 // Create successor steps for all possible paths through the new track.
 616                 for(unsigned i=0; entry_ep.paths>>i; ++i)
 617                         if(entry_ep.has_path(i))
 618                                 create_successor(next, train_index, i, new_steps);
 619         }
 620
 621         if(entry_ep.paths!=train.track->get_type().get_paths() && !train.critical)
 622         {
 623                 /* Create a waiting state before the track if there's at least one path
 624                 that doesn't pass through the entry endpoint. */
 625                 RoutingStep wait(this);
 626                 wait.advance(dt);
 627                 wait.trains[train_index].state = WAITING;
 628
 629                 Time::TimeDelta estimated_wait = Time::day;
 630                 for(unsigned i=0; i<wait.trains.size(); ++i)
 631                         if(i!=static_cast<unsigned>(train_index) && wait.trains[i].state!=ARRIVED)
 632                         {
 633                                 Time::TimeDelta ttp = wait.trains[i].get_time_to_pass(*train.track);
 634                                 estimated_wait = min(estimated_wait, ttp);
 635                         }
 636                 wait.trains[train_index].estimated_wait = estimated_wait;
 637
 638                 wait.update_estimate();
 639                 if(wait.is_viable())
 640                         new_steps.push_back(wait);
 641         }
 642 }
 643
 644 void TrainRoutePlanner::RoutingStep::create_successor(RoutingStep &next, unsigned train_index, unsigned path, list<RoutingStep> &new_steps)
 645 {
 646         TrainRoutingState &train = next.trains[train_index];
 647
 648         train.set_path(path);
 649         next.update_estimate();
 650         if(next.is_viable())
 651                 new_steps.push_back(next);
 652 }
 653
 654 bool TrainRoutePlanner::RoutingStep::update_states()
 655 {
 656         bool changes = false;
 657         for(vector<TrainRoutingState>::iterator i=trains.begin(); i!=trains.end(); ++i)
 658         {
 659                 if(i->state==ARRIVED)
 660                         continue;
 661
 662                 TrainState old_state = i->state;
 663
 664                 TrackIter next_track = i->track.next(i->path);
 665                 if(next_track)
 666                 {
 667                         i->blocked_by = get_occupant(*next_track);
 668                         if(i->blocked_by>=0)
 669                         {
 670                                 /* If the train is still traversing its last critical track, the
 671                                 flag needs to be cleared here to pass viability test. */
 672                                 if(i->info->first_noncritical->has_track(*next_track))
 673                                         i->critical = false;
 674
 675                                 if(i->state!=BLOCKED)
 676                                         i->estimated_wait = trains[i->blocked_by].get_time_to_pass(*next_track);
 677
 678                                 /* Trains in the WAITING state will also transition to BLOCKED and
 679                                 then to MOVING when the other train has passed. */
 680                                 i->state = BLOCKED;
 681                         }
 682                         else if(i->state==BLOCKED)
 683                         {
 684                                 i->estimated_wait = Time::zero;
 685                                 i->state = MOVING;
 686                         }
 687                 }
 688                 else
 689                         i->state = BLOCKED;
 690
 691                 if(i->state!=old_state)
 692                         changes = true;
 693         }
 694
 695         return changes;
 696 }
 697
 698 bool TrainRoutePlanner::RoutingStep::check_deadlocks() const
 699 {
 700         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 701         {
 702                 if(i->state!=BLOCKED)
 703                         continue;
 704
 705                 // A train blocked by end of track is always considered a deadlock.
 706                 if(i->blocked_by<0)
 707                         return true;
 708
 709                 /* Use the tortoise and hare algorithm to check if trains are blocked
 710                 cyclically (A blocks B, which blocks ..., which blocks A). */
 711                 int slow = i->blocked_by;
 712                 int fast = trains[slow].blocked_by;
 713                 while(fast>=0 && trains[fast].blocked_by>=0)
 714                 {
 715                         if(fast==slow)
 716                                 return true;
 717
 718                         slow = trains[slow].blocked_by;
 719                         fast = trains[trains[fast].blocked_by].blocked_by;
 720                 }
 721         }
 722
 723         return false;
 724 }
 725
 726 int TrainRoutePlanner::RoutingStep::get_occupant(Track &track) const
 727 {
 728         for(unsigned i=0; i<trains.size(); ++i)
 729                 if(trains[i].is_occupying(track))
 730                         return i;
 731
 732         return -1;
 733 }
 734
 735 int TrainRoutePlanner::RoutingStep::find_next_train() const
 736 {
 737         /* Pick a moving train with the lowest time to next track.  A train that
 738         just became blocked can still travel until the end of its current track,
 739         so consider those too. */
 740         Time::TimeDelta min_dt;
 741         int next_train = -1;
 742         for(unsigned i=0; i<trains.size(); ++i)
 743         {
 744                 Time::TimeDelta dt;
 745                 if(trains[i].state==MOVING || (trains[i].state==BLOCKED && prev && prev->trains[i].state==MOVING))
 746                         dt = trains[i].get_time_to_next_track();
 747                 else if(trains[i].state==BLOCKED && trains[trains[i].blocked_by].state==ARRIVED)
 748                         dt = trains[i].estimated_wait;
 749                 else
 750                         continue;
 751
 752                 if(dt<min_dt || next_train<0)
 753                 {
 754                         min_dt = dt;
 755                         next_train = i;
 756                 }
 757         }
 758
 759         return next_train;
 760 }
 761
 762 void TrainRoutePlanner::RoutingStep::advance(const Time::TimeDelta &dt)
 763 {
 764         time += dt;
 765         for(vector<TrainRoutingState>::iterator i=trains.begin(); i!=trains.end(); ++i)
 766                 i->advance(dt);
 767 }
 768
 769 void TrainRoutePlanner::RoutingStep::update_estimate()
 770 {
 771         cost_estimate = Time::zero;
 772         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 773                 if(i->remaining_estimate>=0)
 774                         cost_estimate += i->wait_time+i->estimated_wait+((i->distance_traveled+i->remaining_estimate)/i->info->speed)*Time::sec;
 775 }
 776
 777 bool TrainRoutePlanner::RoutingStep::is_viable() const
 778 {
 779         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 780                 if(!i->is_viable())
 781                         return false;
 782
 783         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 784                 if(i->state==MOVING)
 785                         return true;
 786
 787         return false;
 788 }
 789
 790 bool TrainRoutePlanner::RoutingStep::is_goal() const
 791 {
 792         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 793                 if(i->state!=ARRIVED)
 794                         return false;
 795         return true;
 796 }
 797
 798 bool TrainRoutePlanner::RoutingStep::operator<(const RoutingStep &other) const
 799 {
 800         if(preferred!=other.preferred)
 801                 return preferred>other.preferred;
 802         return cost_estimate<other.cost_estimate;
 803 }
 804
 805
 806 TrainRoutePlanner::PlanningThread::PlanningThread(TrainRoutePlanner &p):
 807         planner(p)
 808 {
 809         launch();
 810 }
 811
 812 void TrainRoutePlanner::PlanningThread::main()
 813 {
 814         planner.create_plan();
 815 }
 816
 817 } // namespace R2C2