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         distance_traveled(0),
 312         blocked_by(-1)
 313 {
 314         const Vehicle *veh = &info->train->get_vehicle(0);
 315         // TODO margins
 316         TrackOffsetIter track_and_offs = veh->get_placement().get_position(VehiclePlacement::FRONT_BUFFER);
 317         track = track_and_offs.track_iter();
 318         offset = track_and_offs.offset();
 319         path = track->get_active_path();
 320
 321         while(Vehicle *next = veh->get_link(1))
 322                 veh = next;
 323         track_and_offs = veh->get_placement().get_position(VehiclePlacement::BACK_BUFFER);
 324         back_offset = track_and_offs.offset();
 325
 326         TrackIter iter = track_and_offs.track_iter();
 327         while(1)
 328         {
 329                 occupied_tracks = new OccupiedTrack(*iter, iter->get_active_path(), occupied_tracks);
 330                 if(iter.track()==track.track())
 331                         break;
 332                 iter = iter.next();
 333         }
 334
 335         travel_multiplier = info->metrics[waypoint]->get_travel_multiplier(*track, track.reverse(path).entry());
 336
 337         update_estimate();
 338 }
 339
 340 TrainRoutePlanner::TrainRoutingState::TrainRoutingState(const TrainRoutingState &other):
 341         info(other.info),
 342         track(other.track),
 343         path(other.path),
 344         critical(other.critical),
 345         occupied_tracks(other.occupied_tracks),
 346         offset(other.offset),
 347         back_offset(other.back_offset),
 348         state(other.state),
 349         delay(other.delay),
 350         duration(other.duration),
 351         waypoint(other.waypoint),
 352         travel_multiplier(other.travel_multiplier),
 353         distance_traveled(other.distance_traveled),
 354         remaining_estimate(other.remaining_estimate),
 355         wait_time(other.wait_time),
 356         estimated_wait(other.estimated_wait),
 357         blocked_by(other.blocked_by)
 358 {
 359         ++occupied_tracks->refcount;
 360 }
 361
 362 TrainRoutePlanner::TrainRoutingState::~TrainRoutingState()
 363 {
 364         if(occupied_tracks && !--occupied_tracks->refcount)
 365                 delete occupied_tracks;
 366 }
 367
 368 Time::TimeDelta TrainRoutePlanner::TrainRoutingState::get_time_to_next_track() const
 369 {
 370         return ((occupied_tracks->path_length-offset)/info->speed)*Time::sec+delay+estimated_wait;
 371 }
 372
 373 Time::TimeDelta TrainRoutePlanner::TrainRoutingState::get_time_to_pass(Track &trk) const
 374 {
 375         if(is_occupying(trk))
 376         {
 377                 if(state==ARRIVED && info->has_duration)
 378                         return duration;
 379
 380                 float passed_length = 0;
 381                 for(const OccupiedTrack *occ=occupied_tracks; (occ && occ->track!=&trk); occ=occ->next)
 382                         passed_length += occ->path_length;
 383                 return (max(info->length-passed_length, 0.0f)/info->speed)*Time::sec+delay;
 384         }
 385
 386         for(unsigned wp=waypoint; wp<info->waypoints.size(); ++wp)
 387         {
 388                 float distance = info->metrics[wp]->get_distance_from(trk);
 389                 if(distance>=0 && distance<remaining_estimate)
 390                         return ((remaining_estimate-distance+info->length)/info->speed)*Time::sec+delay;
 391         }
 392
 393         return Time::day;
 394 }
 395
 396 bool TrainRoutePlanner::TrainRoutingState::is_occupying(Track &trk) const
 397 {
 398         if(state==ARRIVED && !duration && info->has_duration)
 399                 return false;
 400
 401         OccupiedTrack *occ = occupied_tracks;
 402         for(unsigned n=occ->n_tracks; n>0; --n, occ=occ->next)
 403                 if(occ->track==&trk)
 404                         return true;
 405         return false;
 406 }
 407
 408 bool TrainRoutePlanner::TrainRoutingState::check_arrival()
 409 {
 410         TrackIter next_track = track.next(path);
 411
 412         // Check if we're about the exit the current waypoint's tracks.
 413         const TrainRouter::Waypoint &wp = info->waypoints[waypoint];
 414         if(wp.chain->has_track(*track) && !wp.chain->has_track(*next_track))
 415                 if(wp.direction==TrackChain::UNSPECIFIED || track==wp.chain->iter_for(*track, wp.direction))
 416                 {
 417                         if(waypoint+1<info->waypoints.size())
 418                                 ++waypoint;
 419                         else
 420                         {
 421                                 state = ARRIVED;
 422                                 return true;
 423                         }
 424                 }
 425
 426         // If we're entering the first non-critical block, clear the critical flag.
 427         if(info->first_noncritical->has_track(*next_track))
 428                 critical = false;
 429
 430         return false;
 431 }
 432
 433 void TrainRoutePlanner::TrainRoutingState::advance(float distance)
 434 {
 435         offset += distance;
 436         back_offset += distance;
 437
 438         // See if the tail end of the train has passed any sensors.
 439         unsigned count_to_free = 0;
 440         unsigned last_sensor_addr = 0;
 441         float distance_after_sensor = 0;
 442         OccupiedTrack *occ = occupied_tracks;
 443         for(unsigned n=occupied_tracks->n_tracks; n>0; --n)
 444         {
 445                 if(unsigned saddr = occ->track->get_sensor_address())
 446                 {
 447                         if(saddr!=last_sensor_addr)
 448                         {
 449                                 count_to_free = 0;
 450                                 distance_after_sensor = 0;
 451                         }
 452                         last_sensor_addr = saddr;
 453                 }
 454
 455                 ++count_to_free;
 456                 distance_after_sensor += occ->path_length;
 457
 458                 occ = occ->next;
 459         }
 460
 461         // Free the last passed sensor and any tracks behind it.
 462         if(count_to_free && back_offset>distance_after_sensor)
 463         {
 464                 back_offset -= distance_after_sensor;
 465                 if(occupied_tracks->refcount>1)
 466                 {
 467                         --occupied_tracks->refcount;
 468                         occupied_tracks = new OccupiedTrack(*occupied_tracks);
 469                 }
 470                 occupied_tracks->n_tracks -= count_to_free;
 471         }
 472
 473         distance_traveled += distance*travel_multiplier;
 474         remaining_estimate -= distance*travel_multiplier;
 475 }
 476
 477 void TrainRoutePlanner::TrainRoutingState::advance(const Time::TimeDelta &dt)
 478 {
 479         if(delay>=dt)
 480         {
 481                 delay -= dt;
 482                 return;
 483         }
 484
 485         float secs = dt/Time::sec;
 486         // There may be some delay remaining.
 487         if(delay)
 488         {
 489                 secs -= delay/Time::sec;
 490                 delay = Time::zero;
 491         }
 492
 493         if(duration)
 494                 duration = max(duration-secs*Time::sec, Time::zero);
 495
 496         if(estimated_wait)
 497                 estimated_wait = max(estimated_wait-secs*Time::sec, Time::zero);
 498
 499         float distance = info->speed*secs;
 500         float remaining_on_track = occupied_tracks->path_length-offset;
 501         if(state==MOVING || distance<remaining_on_track)
 502                 advance(info->speed*secs);
 503         else if(state!=ARRIVED)
 504         {
 505                 if(remaining_on_track>0)
 506                 {
 507                         advance(remaining_on_track);
 508                         wait_time += (secs-remaining_on_track/info->speed)*Time::sec;
 509                 }
 510                 else
 511                         wait_time += secs*Time::sec;
 512         }
 513 }
 514
 515 void TrainRoutePlanner::TrainRoutingState::advance_track(unsigned next_path)
 516 {
 517         float distance = occupied_tracks->path_length-offset;
 518
 519         track = track.next(path);
 520         path = next_path;
 521         occupied_tracks = new OccupiedTrack(*track, path, occupied_tracks);
 522
 523         advance(distance);
 524         offset = 0;
 525         travel_multiplier = info->metrics[waypoint]->get_travel_multiplier(*track, track.reverse(path).entry());
 526 }
 527
 528 void TrainRoutePlanner::TrainRoutingState::set_path(unsigned p)
 529 {
 530         path = p;
 531         OccupiedTrack *next_occ = occupied_tracks->next;
 532         if(!--occupied_tracks->refcount)
 533                 delete occupied_tracks;
 534         occupied_tracks = new OccupiedTrack(*track, path, next_occ);
 535         update_estimate();
 536 }
 537
 538 void TrainRoutePlanner::TrainRoutingState::update_estimate()
 539 {
 540         TrackIter iter = track.reverse(path);
 541         const TrainRouteMetric *metric = info->metrics[waypoint];
 542         remaining_estimate = metric->get_distance_from(*iter, iter.entry());
 543         travel_multiplier = metric->get_travel_multiplier(*iter, iter.entry());
 544         if(remaining_estimate>=0)
 545                 remaining_estimate += (occupied_tracks->path_length-offset)*travel_multiplier;
 546 }
 547
 548 bool TrainRoutePlanner::TrainRoutingState::is_viable() const
 549 {
 550         if(remaining_estimate<0)
 551                 return false;
 552         if(critical && state==BLOCKED)
 553                 return false;
 554         return true;
 555 }
 556
 557
 558 TrainRoutePlanner::RoutingStep::RoutingStep():
 559         preferred(false),
 560         prev(0)
 561 { }
 562
 563 TrainRoutePlanner::RoutingStep::RoutingStep(const RoutingStep *p):
 564         time(p->time),
 565         cost_estimate(p->cost_estimate),
 566         preferred(false),
 567         trains(p->trains),
 568         prev(p)
 569 { }
 570
 571 void TrainRoutePlanner::RoutingStep::create_successors(list<RoutingStep> &new_steps) const
 572 {
 573         RoutingStep next(this);
 574         if(next.update_states() && next.check_deadlocks())
 575                 return;
 576
 577         int train_index = next.find_next_train();
 578         if(train_index<0)
 579                 return;
 580
 581         TrainRoutingState &train = next.trains[train_index];
 582
 583         Time::TimeDelta dt = train.get_time_to_next_track();
 584         next.advance(dt);
 585
 586         /* Check arrival after the train has advanced to the end of its current track
 587         so travel time and occupied tracks will be correct. */
 588         if(train.check_arrival())
 589         {
 590                 new_steps.push_back(next);
 591                 return;
 592         }
 593
 594         if(train.state==MOVING)
 595                 train.advance_track(0);
 596         else
 597         {
 598                 new_steps.push_back(next);
 599                 return;
 600         }
 601
 602         const TrackType::Endpoint &entry_ep = train.track.endpoint();
 603         if(train.critical)
 604         {
 605                 /* Only create a successor step matching the currently set path for a
 606                 critical track. */
 607                 unsigned critical_path = train.track->get_type().coerce_path(train.track.entry(), train.track->get_active_path());
 608                 create_successor(next, train_index, critical_path, new_steps);
 609         }
 610         else
 611         {
 612                 // Create successor steps for all possible paths through the new track.
 613                 for(unsigned i=0; entry_ep.paths>>i; ++i)
 614                         if(entry_ep.has_path(i))
 615                                 create_successor(next, train_index, i, new_steps);
 616         }
 617
 618         if(entry_ep.paths!=train.track->get_type().get_paths() && !train.critical)
 619         {
 620                 /* Create a waiting state before the track if there's at least one path
 621                 that doesn't pass through the entry endpoint. */
 622                 RoutingStep wait(this);
 623                 wait.advance(dt);
 624                 wait.trains[train_index].state = WAITING;
 625
 626                 Time::TimeDelta estimated_wait = Time::day;
 627                 for(unsigned i=0; i<wait.trains.size(); ++i)
 628                         if(i!=static_cast<unsigned>(train_index) && wait.trains[i].state!=ARRIVED)
 629                         {
 630                                 Time::TimeDelta ttp = wait.trains[i].get_time_to_pass(*train.track);
 631                                 estimated_wait = min(estimated_wait, ttp);
 632                         }
 633                 wait.trains[train_index].estimated_wait = estimated_wait;
 634
 635                 wait.update_estimate();
 636                 if(wait.is_viable())
 637                         new_steps.push_back(wait);
 638         }
 639 }
 640
 641 void TrainRoutePlanner::RoutingStep::create_successor(RoutingStep &next, unsigned train_index, unsigned path, list<RoutingStep> &new_steps)
 642 {
 643         TrainRoutingState &train = next.trains[train_index];
 644
 645         train.set_path(path);
 646         next.update_estimate();
 647         if(next.is_viable())
 648                 new_steps.push_back(next);
 649 }
 650
 651 bool TrainRoutePlanner::RoutingStep::update_states()
 652 {
 653         bool changes = false;
 654         for(vector<TrainRoutingState>::iterator i=trains.begin(); i!=trains.end(); ++i)
 655         {
 656                 if(i->state==ARRIVED)
 657                         continue;
 658
 659                 TrainState old_state = i->state;
 660
 661                 TrackIter next_track = i->track.next(i->path);
 662                 if(next_track)
 663                 {
 664                         i->blocked_by = get_occupant(*next_track);
 665                         if(i->blocked_by>=0)
 666                         {
 667                                 /* If the train is still traversing its last critical track, the
 668                                 flag needs to be cleared here to pass viability test. */
 669                                 if(i->info->first_noncritical->has_track(*next_track))
 670                                         i->critical = false;
 671
 672                                 if(i->state!=BLOCKED)
 673                                         i->estimated_wait = trains[i->blocked_by].get_time_to_pass(*next_track);
 674
 675                                 /* Trains in the WAITING state will also transition to BLOCKED and
 676                                 then to MOVING when the other train has passed. */
 677                                 i->state = BLOCKED;
 678                         }
 679                         else if(i->state==BLOCKED)
 680                         {
 681                                 i->estimated_wait = Time::zero;
 682                                 i->state = MOVING;
 683                         }
 684                 }
 685                 else
 686                         i->state = BLOCKED;
 687
 688                 if(i->state!=old_state)
 689                         changes = true;
 690         }
 691
 692         return changes;
 693 }
 694
 695 bool TrainRoutePlanner::RoutingStep::check_deadlocks() const
 696 {
 697         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 698         {
 699                 if(i->state!=BLOCKED)
 700                         continue;
 701
 702                 // A train blocked by end of track is always considered a deadlock.
 703                 if(i->blocked_by<0)
 704                         return true;
 705
 706                 /* Use the tortoise and hare algorithm to check if trains are blocked
 707                 cyclically (A blocks B, which blocks ..., which blocks A). */
 708                 int slow = i->blocked_by;
 709                 int fast = trains[slow].blocked_by;
 710                 while(fast>=0 && trains[fast].blocked_by>=0)
 711                 {
 712                         if(fast==slow)
 713                                 return true;
 714
 715                         slow = trains[slow].blocked_by;
 716                         fast = trains[trains[fast].blocked_by].blocked_by;
 717                 }
 718         }
 719
 720         return false;
 721 }
 722
 723 int TrainRoutePlanner::RoutingStep::get_occupant(Track &track) const
 724 {
 725         for(unsigned i=0; i<trains.size(); ++i)
 726                 if(trains[i].is_occupying(track))
 727                         return i;
 728
 729         return -1;
 730 }
 731
 732 int TrainRoutePlanner::RoutingStep::find_next_train() const
 733 {
 734         /* Pick a moving train with the lowest time to next track.  A train that
 735         just became blocked can still travel until the end of its current track,
 736         so consider those too. */
 737         Time::TimeDelta min_dt;
 738         int next_train = -1;
 739         for(unsigned i=0; i<trains.size(); ++i)
 740         {
 741                 Time::TimeDelta dt;
 742                 if(trains[i].state==MOVING || (trains[i].state==BLOCKED && prev && prev->trains[i].state==MOVING))
 743                         dt = trains[i].get_time_to_next_track();
 744                 else if(trains[i].state==BLOCKED && trains[trains[i].blocked_by].state==ARRIVED)
 745                         dt = trains[i].estimated_wait;
 746                 else
 747                         continue;
 748
 749                 if(dt<min_dt || next_train<0)
 750                 {
 751                         min_dt = dt;
 752                         next_train = i;
 753                 }
 754         }
 755
 756         return next_train;
 757 }
 758
 759 void TrainRoutePlanner::RoutingStep::advance(const Time::TimeDelta &dt)
 760 {
 761         time += dt;
 762         for(vector<TrainRoutingState>::iterator i=trains.begin(); i!=trains.end(); ++i)
 763                 i->advance(dt);
 764 }
 765
 766 void TrainRoutePlanner::RoutingStep::update_estimate()
 767 {
 768         cost_estimate = Time::zero;
 769         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 770                 if(i->remaining_estimate>=0)
 771                         cost_estimate += i->wait_time+i->estimated_wait+((i->distance_traveled+i->remaining_estimate)/i->info->speed)*Time::sec;
 772 }
 773
 774 bool TrainRoutePlanner::RoutingStep::is_viable() const
 775 {
 776         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 777                 if(!i->is_viable())
 778                         return false;
 779
 780         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 781                 if(i->state==MOVING)
 782                         return true;
 783
 784         return false;
 785 }
 786
 787 bool TrainRoutePlanner::RoutingStep::is_goal() const
 788 {
 789         for(vector<TrainRoutingState>::const_iterator i=trains.begin(); i!=trains.end(); ++i)
 790                 if(i->state!=ARRIVED)
 791                         return false;
 792         return true;
 793 }
 794
 795 bool TrainRoutePlanner::RoutingStep::operator<(const RoutingStep &other) const
 796 {
 797         if(preferred!=other.preferred)
 798                 return preferred>other.preferred;
 799         return cost_estimate<other.cost_estimate;
 800 }
 801
 802
 803 TrainRoutePlanner::PlanningThread::PlanningThread(TrainRoutePlanner &p):
 804         planner(p)
 805 {
 806         launch();
 807 }
 808
 809 void TrainRoutePlanner::PlanningThread::main()
 810 {
 811         planner.create_plan();
 812 }
 813
 814 } // namespace R2C2