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(unsigned n_wps = router->get_n_waypoints())
 253         {
 254                 waypoints.reserve(n_wps),
 255                 metrics.reserve(n_wps);
 256                 for(unsigned i=0; i<n_wps; ++i)
 257                 {
 258                         waypoints.push_back(router->get_waypoint(i));
 259                         metrics.push_back(&router->get_metric(i));
 260                 }
 261                 has_duration = router->get_trip_duration();
 262         }
 263
 264         unsigned n_vehs = train->get_n_vehicles();
 265         for(unsigned i=0; i<n_vehs; ++i)
 266                 length += train->get_vehicle(i).get_type().get_length();
 267
 268         // If no maximum speed is specified, use a sensible default
 269         if(!speed)
 270                 speed = 20*train->get_layout().get_catalogue().get_scale();
 271 }
 272
 273
 274 TrainRoutePlanner::OccupiedTrack::OccupiedTrack(Track &t, unsigned p, OccupiedTrack *n):
 275         track(&t),
 276         path_length(track->get_type().get_path_length(p)),
 277         next(n),
 278         n_tracks(next ? next->n_tracks+1 : 1),
 279         refcount(1)
 280 {
 281         if(next)
 282                 ++next->refcount;
 283 }
 284
 285 TrainRoutePlanner::OccupiedTrack::OccupiedTrack(const OccupiedTrack &other):
 286         track(other.track),
 287         path_length(other.path_length),
 288         next(other.next),
 289         n_tracks(other.n_tracks),
 290         refcount(1)
 291 {
 292         if(next)
 293                 ++next->refcount;
 294 }
 295
 296 TrainRoutePlanner::OccupiedTrack::~OccupiedTrack()
 297 {
 298         if(next && !--next->refcount)
 299                 delete next;
 300 }
 301
 302
 303 TrainRoutePlanner::TrainRoutingState::TrainRoutingState(TrainRoutingInfo &inf):
 304         info(&inf),
 305         critical(true),
 306         occupied_tracks(0),
 307         state(MOVING),
 308         delay(info->router->get_departure_delay()),
 309         duration(info->router->get_trip_duration()),
 310         waypoint(0),
 311         blocked_by(-1)
 312 {
 313         const Vehicle *veh = &info->train->get_vehicle(0);
 314         // TODO margins
 315         TrackOffsetIter track_and_offs = veh->get_placement().get_position(VehiclePlacement::FRONT_BUFFER);
 316         track = track_and_offs.track_iter();
 317         offset = track_and_offs.offset();
 318         path = track->get_active_path();
 319
 320         while(Vehicle *next = veh->get_link(1))
 321                 veh = next;
 322         track_and_offs = veh->get_placement().get_position(VehiclePlacement::BACK_BUFFER);
 323         back_offset = track_and_offs.offset();
 324
 325         TrackIter iter = track_and_offs.track_iter();
 326         while(1)
 327         {
 328                 occupied_tracks = new OccupiedTrack(*iter, iter->get_active_path(), occupied_tracks);
 329                 if(iter.track()==track.track())
 330                         break;
 331                 iter = iter.next();
 332         }
 333
 334         travel_multiplier = info->metrics[waypoint]->get_travel_multiplier(*track, track.reverse(path).entry());
 335
 336         update_estimate();
 337 }
 338
 339 TrainRoutePlanner::TrainRoutingState::TrainRoutingState(const TrainRoutingState &other):
 340         info(other.info),
 341         track(other.track),
 342         path(other.path),
 343         critical(other.critical),
 344         occupied_tracks(other.occupied_tracks),
 345         offset(other.offset),
 346         back_offset(other.back_offset),
 347         state(other.state),
 348         delay(other.delay),
 349         duration(other.duration),
 350         waypoint(other.waypoint),
 351         travel_multiplier(other.travel_multiplier),
 352         distance_traveled(other.distance_traveled),
 353         remaining_estimate(other.remaining_estimate),
 354         wait_time(other.wait_time),
 355         estimated_wait(other.estimated_wait),
 356         blocked_by(other.blocked_by)
 357 {
 358         ++occupied_tracks->refcount;
 359 }
 360
 361 TrainRoutePlanner::TrainRoutingState::~TrainRoutingState()
 362 {
 363         if(occupied_tracks && !--occupied_tracks->refcount)
 364                 delete occupied_tracks;
 365 }
 366
 367 Time::TimeDelta TrainRoutePlanner::TrainRoutingState::get_time_to_next_track() const
 368 {
 369         return ((occupied_tracks->path_length-offset)/info->speed)*Time::sec+delay;
 370 }
 371
 372 Time::TimeDelta TrainRoutePlanner::TrainRoutingState::get_time_to_pass(Track &trk) const
 373 {
 374         if(is_occupying(trk))
 375         {
 376                 float passed_length = 0;
 377                 for(const OccupiedTrack *occ=occupied_tracks; (occ && occ->track!=&trk); occ=occ->next)
 378                         passed_length += occ->path_length;
 379                 return (max(info->length-passed_length, 0.0f)/info->speed)*Time::sec+delay;
 380         }
 381
 382         for(unsigned wp=waypoint; wp<info->waypoints.size(); ++wp)
 383         {
 384                 float distance = info->metrics[wp]->get_distance_from(trk);
 385                 if(distance>=0 && distance<remaining_estimate)
 386                         return ((remaining_estimate-distance+info->length)/info->speed)*Time::sec+delay;
 387         }
 388
 389         return Time::day;
 390 }
 391
 392 bool TrainRoutePlanner::TrainRoutingState::is_occupying(Track &trk) const
 393 {
 394         if(state==ARRIVED && !duration && info->has_duration)
 395                 return false;
 396
 397         OccupiedTrack *occ = occupied_tracks;
 398         for(unsigned n=occ->n_tracks; n>0; --n, occ=occ->next)
 399                 if(occ->track==&trk)
 400                         return true;
 401         return false;
 402 }
 403
 404 bool TrainRoutePlanner::TrainRoutingState::check_arrival()
 405 {
 406         TrackIter next_track = track.next(path);
 407
 408         // Check if we're about the exit the current waypoint's tracks.
 409         const TrainRouter::Waypoint &wp = info->waypoints[waypoint];
 410         if(wp.chain->has_track(*track) && !wp.chain->has_track(*next_track))
 411                 if(wp.direction==TrackChain::UNSPECIFIED || track==wp.chain->iter_for(*track, wp.direction))
 412                 {
 413                         if(waypoint+1<info->waypoints.size())
 414                                 ++waypoint;
 415                         else
 416                         {
 417                                 state = ARRIVED;
 418                                 return true;
 419                         }
 420                 }
 421
 422         // If we're entering the first non-critical block, clear the critical flag.
 423         if(info->first_noncritical->has_track(*next_track))
 424                 critical = false;
 425
 426         return false;
 427 }
 428
 429 void TrainRoutePlanner::TrainRoutingState::advance(float distance)
 430 {
 431         offset += distance;
 432         back_offset += distance;
 433
 434         // See if the tail end of the train has passed any sensors.
 435         unsigned count_to_free = 0;
 436         unsigned last_sensor_addr = 0;
 437         float distance_after_sensor = 0;
 438         OccupiedTrack *occ = occupied_tracks;
 439         for(unsigned n=occupied_tracks->n_tracks; n>0; --n)
 440         {
 441                 if(unsigned saddr = occ->track->get_sensor_address())
 442                 {
 443                         if(saddr!=last_sensor_addr)
 444                         {
 445                                 count_to_free = 0;
 446                                 distance_after_sensor = 0;
 447                         }
 448                         last_sensor_addr = saddr;
 449                 }
 450
 451                 ++count_to_free;
 452                 distance_after_sensor += occ->path_length;
 453
 454                 occ = occ->next;
 455         }
 456
 457         // Free the last passed sensor and any tracks behind it.
 458         if(count_to_free && back_offset>distance_after_sensor)
 459         {
 460                 back_offset -= distance_after_sensor;
 461                 if(occupied_tracks->refcount>1)
 462                 {
 463                         --occupied_tracks->refcount;
 464                         occupied_tracks = new OccupiedTrack(*occupied_tracks);
 465                 }
 466                 occupied_tracks->n_tracks -= count_to_free;
 467         }
 468
 469         distance_traveled += distance*travel_multiplier;
 470         remaining_estimate -= distance*travel_multiplier;
 471 }
 472
 473 void TrainRoutePlanner::TrainRoutingState::advance(const Time::TimeDelta &dt)
 474 {
 475         if(delay>=dt)
 476         {
 477                 delay -= dt;
 478                 return;
 479         }
 480
 481         float secs = dt/Time::sec;
 482         // There may be some delay remaining.
 483         if(delay)
 484         {
 485                 secs -= delay/Time::sec;
 486                 delay = Time::zero;
 487         }
 488
 489         if(duration)
 490                 duration = max(duration-secs*Time::sec, Time::zero);
 491
 492         if(estimated_wait)
 493                 estimated_wait = max(estimated_wait-secs*Time::sec, Time::zero);
 494
 495         if(state==MOVING)
 496                 advance(info->speed*secs);
 497         else if(state!=ARRIVED)
 498         {
 499                 float remaining_distance = occupied_tracks->path_length-offset;
 500                 if(remaining_distance>0)
 501                 {
 502                         advance(remaining_distance);
 503                         wait_time += (secs-remaining_distance/info->speed)*Time::sec;
 504                 }
 505                 else
 506                         wait_time += secs*Time::sec;
 507         }
 508 }
 509
 510 void TrainRoutePlanner::TrainRoutingState::advance_track(unsigned next_path)
 511 {
 512         float distance = occupied_tracks->path_length-offset;
 513
 514         track = track.next(path);
 515         path = next_path;
 516         occupied_tracks = new OccupiedTrack(*track, path, occupied_tracks);
 517
 518         advance(distance);
 519         offset = 0;
 520         travel_multiplier = info->metrics[waypoint]->get_travel_multiplier(*track, track.reverse(path).entry());
 521 }
 522
 523 void TrainRoutePlanner::TrainRoutingState::set_path(unsigned p)
 524 {
 525         path = p;
 526         OccupiedTrack *next_occ = occupied_tracks->next;
 527         if(!--occupied_tracks->refcount)
 528                 delete occupied_tracks;
 529         occupied_tracks = new OccupiedTrack(*track, path, next_occ);
 530         update_estimate();
 531 }
 532
 533 void TrainRoutePlanner::TrainRoutingState::update_estimate()
 534 {
 535         TrackIter iter = track.reverse(path);
 536         const TrainRouteMetric *metric = info->metrics[waypoint];
 537         remaining_estimate = metric->get_distance_from(*iter, iter.entry());
 538         travel_multiplier = metric->get_travel_multiplier(*iter, iter.entry());
 539         if(remaining_estimate>=0)
 540                 remaining_estimate += (occupied_tracks->path_length-offset)*travel_multiplier;
 541 }
 542
 543 bool TrainRoutePlanner::TrainRoutingState::is_viable() const
 544 {
 545         if(remaining_estimate<0)
 546                 return false;
 547         if(critical && state==BLOCKED)
 548                 return false;
 549         return true;
 550 }
 551
 552
 553 TrainRoutePlanner::RoutingStep::RoutingStep():
 554         preferred(false),
 555         prev(0)
 556 { }
 557
 558 TrainRoutePlanner::RoutingStep::RoutingStep(const RoutingStep *p):
 559         time(p->time),
 560         cost_estimate(p->cost_estimate),
 561         preferred(false),
 562         trains(p->trains),
 563         prev(p)
 564 { }
 565
 566 void TrainRoutePlanner::RoutingStep::create_successors(list<RoutingStep> &new_steps) const
 567 {
 568         RoutingStep next(this);
 569         if(next.update_states() && next.check_deadlocks())
 570                 return;
 571
 572         int train_index = next.find_next_train();
 573         if(train_index<0)
 574                 return;
 575
 576         TrainRoutingState &train = next.trains[train_index];
 577
 578         Time::TimeDelta dt = train.get_time_to_next_track();
 579         next.advance(dt);
 580
 581         /* Check arrival after the train has advanced to the end of its current track
 582         so travel time and occupied tracks will be correct. */
 583         if(train.check_arrival())
 584         {
 585                 new_steps.push_back(next);
 586                 return;
 587         }
 588
 589         if(train.state==MOVING)
 590                 train.advance_track(0);
 591         else
 592         {
 593                 new_steps.push_back(next);
 594                 return;
 595         }
 596
 597         const TrackType::Endpoint &entry_ep = train.track.endpoint();
 598         if(train.critical)
 599         {
 600                 /* Only create a successor step matching the currently set path for a
 601                 critical track. */
 602                 unsigned critical_path = train.track->get_type().coerce_path(train.track.entry(), train.track->get_active_path());
 603                 create_successor(next, train_index, critical_path, new_steps);
 604         }
 605         else
 606         {
 607                 // Create successor steps for all possible paths through the new track.
 608                 for(unsigned i=0; entry_ep.paths>>i; ++i)
 609                         if(entry_ep.has_path(i))
 610                                 create_successor(next, train_index, i, new_steps);
 611         }
 612
 613         if(entry_ep.paths!=train.track->get_type().get_paths() && !train.critical)
 614         {
 615                 /* Create a waiting state before the track if there's at least one path
 616                 that doesn't pass through the entry endpoint. */
 617                 RoutingStep wait(this);
 618                 wait.advance(dt);
 619                 wait.trains[train_index].state = WAITING;
 620
 621                 Time::TimeDelta estimated_wait = Time::day;
 622                 for(unsigned i=0; i<wait.trains.size(); ++i)
 623                         if(i!=static_cast<unsigned>(train_index) && wait.trains[i].state!=ARRIVED)
 624                         {
 625                                 Time::TimeDelta ttp = wait.trains[i].get_time_to_pass(*train.track);
 626                                 estimated_wait = min(estimated_wait, ttp);
 627                         }
 628                 wait.trains[train_index].estimated_wait = estimated_wait;
 629
 630                 wait.update_estimate();
 631                 if(wait.is_viable())
 632                         new_steps.push_back(wait);
 633         }
 634 }
 635
 636 void TrainRoutePlanner::RoutingStep::create_successor(RoutingStep &next, unsigned train_index, unsigned path, list<RoutingStep> &new_steps)
 637 {
 638         TrainRoutingState &train = next.trains[train_index];
 639
 640         train.set_path(path);
 641         next.update_estimate();
 642         if(next.is_viable())
 643                 new_steps.push_back(next);
 644 }
 645
 646 bool TrainRoutePlanner::RoutingStep::update_states()
 647 {
 648         bool changes = false;
 649         for(vector<TrainRoutingState>::iterator i=trains.begin(); i!=trains.end(); ++i)
 650         {
 651                 if(i->state==ARRIVED)
 652                         continue;
 653
 654                 TrainState old_state = i->state;
 655
 656                 TrackIter next_track = i->track.next(i->path);
 657                 if(next_track)
 658                 {
 659                         i->blocked_by = get_occupant(*next_track);
 660                         if(i->blocked_by>=0)
 661                         {
 662                                 /* If the train is still traversing its last critical track, the
 663                                 flag needs to be cleared here to pass viability test. */
 664                                 if(i->info->first_noncritical->has_track(*next_track))
 665                                         i->critical = false;
 666
 667                                 if(i->state!=BLOCKED)
 668                                         i->estimated_wait = trains[i->blocked_by].get_time_to_pass(*next_track);
 669
 670                                 /* Trains in the WAITING state will also transition to BLOCKED and
 671                                 then to MOVING when the other train has passed. */
 672                                 i->state = BLOCKED;
 673                         }
 674                         else if(i->state==BLOCKED)
 675                         {
 676                                 i->estimated_wait = Time::zero;
 677                                 i->state = MOVING;
 678                         }
 679                 }
 680                 else
 681                         i->state = BLOCKED;
 682
 683                 if(i->state!=old_state)
 684                         changes = true;
 685         }
 686
 687         return changes;
 688 }
 689
 690 bool TrainRoutePlanner::RoutingStep::check_deadlocks() const
 691 {
 692         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 693         {
 694                 if(i->state!=BLOCKED)
 695                         continue;
 696
 697                 // A train blocked by end of track is always considered a deadlock.
 698                 if(i->blocked_by<0)
 699                         return true;
 700
 701                 /* Use the tortoise and hare algorithm to check if trains are blocked
 702                 cyclically (A blocks B, which blocks ..., which blocks A). */
 703                 int slow = i->blocked_by;
 704                 int fast = trains[slow].blocked_by;
 705                 while(fast>=0 && trains[fast].blocked_by>=0)
 706                 {
 707                         if(fast==slow)
 708                                 return true;
 709
 710                         slow = trains[slow].blocked_by;
 711                         fast = trains[trains[fast].blocked_by].blocked_by;
 712                 }
 713         }
 714
 715         return false;
 716 }
 717
 718 int TrainRoutePlanner::RoutingStep::get_occupant(Track &track) const
 719 {
 720         for(unsigned i=0; i<trains.size(); ++i)
 721                 if(trains[i].is_occupying(track))
 722                         return i;
 723
 724         return -1;
 725 }
 726
 727 int TrainRoutePlanner::RoutingStep::find_next_train() const
 728 {
 729         /* Pick a moving train with the lowest time to next track.  A train that
 730         just became blocked can still travel until the end of its current track,
 731         so consider those too. */
 732         Time::TimeDelta min_dt;
 733         int next_train = -1;
 734         for(unsigned i=0; i<trains.size(); ++i)
 735                 if(trains[i].state==MOVING || (trains[i].state==BLOCKED && prev && prev->trains[i].state==MOVING))
 736                 {
 737                         Time::TimeDelta dt = trains[i].get_time_to_next_track();
 738                         if(dt<min_dt || next_train<0)
 739                         {
 740                                 min_dt = dt;
 741                                 next_train = i;
 742                         }
 743                 }
 744
 745         return next_train;
 746 }
 747
 748 void TrainRoutePlanner::RoutingStep::advance(const Time::TimeDelta &dt)
 749 {
 750         time += dt;
 751         for(vector<TrainRoutingState>::iterator i=trains.begin(); i!=trains.end(); ++i)
 752                 i->advance(dt);
 753 }
 754
 755 void TrainRoutePlanner::RoutingStep::update_estimate()
 756 {
 757         cost_estimate = Time::zero;
 758         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 759                 if(i->remaining_estimate>=0)
 760                         cost_estimate += i->wait_time+i->estimated_wait+((i->distance_traveled+i->remaining_estimate)/i->info->speed)*Time::sec;
 761 }
 762
 763 bool TrainRoutePlanner::RoutingStep::is_viable() const
 764 {
 765         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 766                 if(!i->is_viable())
 767                         return false;
 768
 769         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 770                 if(i->state==MOVING)
 771                         return true;
 772
 773         return false;
 774 }
 775
 776 bool TrainRoutePlanner::RoutingStep::is_goal() const
 777 {
 778         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 779                 if(i->state!=ARRIVED)
 780                         return false;
 781         return true;
 782 }
 783
 784 bool TrainRoutePlanner::RoutingStep::operator<(const RoutingStep &other) const
 785 {
 786         if(preferred!=other.preferred)
 787                 return preferred>other.preferred;
 788         return cost_estimate<other.cost_estimate;
 789 }
 790
 791
 792 TrainRoutePlanner::PlanningThread::PlanningThread(TrainRoutePlanner &p):
 793         planner(p)
 794 {
 795         launch();
 796 }
 797
 798 void TrainRoutePlanner::PlanningThread::main()
 799 {
 800         planner.create_plan();
 801 }
 802
 803 } // namespace R2C2