uct/uct.c

   1 #include <assert.h>
   2 #include <math.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include <time.h>
   7
   8 #define DEBUG
   9
  10 #include "debug.h"
  11 #include "board.h"
  12 #include "gtp.h"
  13 #include "move.h"
  14 #include "mq.h"
  15 #include "joseki/base.h"
  16 #include "playout.h"
  17 #include "playout/moggy.h"
  18 #include "playout/light.h"
  19 #include "tactics/util.h"
  20 #include "timeinfo.h"
  21 #include "uct/dynkomi.h"
  22 #include "uct/internal.h"
  23 #include "uct/plugins.h"
  24 #include "uct/prior.h"
  25 #include "uct/search.h"
  26 #include "uct/slave.h"
  27 #include "uct/tree.h"
  28 #include "uct/uct.h"
  29 #include "uct/walk.h"
  30
  31 struct uct_policy *policy_ucb1_init(struct uct *u, char *arg);
  32 struct uct_policy *policy_ucb1amaf_init(struct uct *u, char *arg);
  33 static void uct_pondering_start(struct uct *u, struct board *b0, struct tree *t, enum stone color);
  34
  35 /* Maximal simulation length. */
  36 #define MC_GAMELEN      MAX_GAMELEN
  37
  38
  39 static void
  40 setup_state(struct uct *u, struct board *b, enum stone color)
  41 {
  42         u->t = tree_init(b, color, u->fast_alloc ? u->max_tree_size : 0,
  43                          u->max_pruned_size, u->pruning_threshold, u->local_tree_aging, u->stats_hbits);
  44         if (u->force_seed)
  45                 fast_srandom(u->force_seed);
  46         if (UDEBUGL(0))
  47                 fprintf(stderr, "Fresh board with random seed %lu\n", fast_getseed());
  48         //board_print(b, stderr);
  49         if (!u->no_tbook && b->moves == 0) {
  50                 assert(color == S_BLACK);
  51                 tree_load(u->t, b);
  52         }
  53 }
  54
  55 static void
  56 reset_state(struct uct *u)
  57 {
  58         assert(u->t);
  59         tree_done(u->t); u->t = NULL;
  60 }
  61
  62 static void
  63 setup_dynkomi(struct uct *u, struct board *b, enum stone to_play)
  64 {
  65         if (u->t->use_extra_komi && !u->pondering && u->dynkomi->permove)
  66                 u->t->extra_komi = u->dynkomi->permove(u->dynkomi, b, u->t);
  67         else if (!u->t->use_extra_komi)
  68                 u->t->extra_komi = 0;
  69 }
  70
  71 void
  72 uct_prepare_move(struct uct *u, struct board *b, enum stone color)
  73 {
  74         if (u->t) {
  75                 /* Verify that we have sane state. */
  76                 assert(b->es == u);
  77                 assert(u->t && b->moves);
  78                 if (color != stone_other(u->t->root_color)) {
  79                         fprintf(stderr, "Fatal: Non-alternating play detected %d %d\n",
  80                                 color, u->t->root_color);
  81                         exit(1);
  82                 }
  83                 uct_htable_reset(u->t);
  84
  85         } else {
  86                 /* We need fresh state. */
  87                 b->es = u;
  88                 setup_state(u, b, color);
  89         }
  90
  91         u->ownermap.playouts = 0;
  92         memset(u->ownermap.map, 0, board_size2(b) * sizeof(u->ownermap.map[0]));
  93         u->played_own = u->played_all = 0;
  94 }
  95
  96 static void
  97 dead_group_list(struct uct *u, struct board *b, struct move_queue *mq)
  98 {
  99         struct group_judgement gj;
 100         gj.thres = GJ_THRES;
 101         gj.gs = alloca(board_size2(b) * sizeof(gj.gs[0]));
 102         board_ownermap_judge_group(b, &u->ownermap, &gj);
 103         groups_of_status(b, &gj, GS_DEAD, mq);
 104 }
 105
 106 bool
 107 uct_pass_is_safe(struct uct *u, struct board *b, enum stone color, bool pass_all_alive)
 108 {
 109         if (u->ownermap.playouts < GJ_MINGAMES)
 110                 return false;
 111
 112         struct move_queue mq = { .moves = 0 };
 113         dead_group_list(u, b, &mq);
 114         if (pass_all_alive && mq.moves > 0)
 115                 return false; // We need to remove some dead groups first.
 116         return pass_is_safe(b, color, &mq);
 117 }
 118
 119 static char *
 120 uct_printhook_ownermap(struct board *board, coord_t c, char *s, char *end)
 121 {
 122         struct uct *u = board->es;
 123         if (!u) {
 124                 strcat(s, ". ");
 125                 return s + 2;
 126         }
 127         const char chr[] = ":XO,"; // dame, black, white, unclear
 128         const char chm[] = ":xo,";
 129         char ch = chr[board_ownermap_judge_point(&u->ownermap, c, GJ_THRES)];
 130         if (ch == ',') { // less precise estimate then?
 131                 ch = chm[board_ownermap_judge_point(&u->ownermap, c, 0.67)];
 132         }
 133         s += snprintf(s, end - s, "%c ", ch);
 134         return s;
 135 }
 136
 137 static char *
 138 uct_notify_play(struct engine *e, struct board *b, struct move *m)
 139 {
 140         struct uct *u = e->data;
 141         if (!u->t) {
 142                 /* No state, create one - this is probably game beginning
 143                  * and we need to load the opening tbook right now. */
 144                 uct_prepare_move(u, b, m->color);
 145                 assert(u->t);
 146         }
 147
 148         /* Stop pondering, required by tree_promote_at() */
 149         uct_pondering_stop(u);
 150         if (UDEBUGL(2) && u->slave)
 151                 tree_dump(u->t, u->dumpthres);
 152
 153         if (is_resign(m->coord)) {
 154                 /* Reset state. */
 155                 reset_state(u);
 156                 return NULL;
 157         }
 158
 159         /* Promote node of the appropriate move to the tree root. */
 160         assert(u->t->root);
 161         if (!tree_promote_at(u->t, b, m->coord)) {
 162                 if (UDEBUGL(0))
 163                         fprintf(stderr, "Warning: Cannot promote move node! Several play commands in row?\n");
 164                 reset_state(u);
 165                 return NULL;
 166         }
 167
 168         /* If we are a slave in a distributed engine, start pondering once
 169          * we know which move we actually played. See uct_genmove() about
 170          * the check for pass. */
 171         if (u->pondering_opt && u->slave && m->color == u->my_color && !is_pass(m->coord))
 172                 uct_pondering_start(u, b, u->t, stone_other(m->color));
 173
 174         return NULL;
 175 }
 176
 177 static char *
 178 uct_undo(struct engine *e, struct board *b)
 179 {
 180         struct uct *u = e->data;
 181
 182         if (!u->t) return NULL;
 183         uct_pondering_stop(u);
 184         reset_state(u);
 185         return NULL;
 186 }
 187
 188 static char *
 189 uct_result(struct engine *e, struct board *b)
 190 {
 191         struct uct *u = e->data;
 192         static char reply[1024];
 193
 194         if (!u->t)
 195                 return NULL;
 196         enum stone color = u->t->root_color;
 197         struct tree_node *n = u->t->root;
 198         snprintf(reply, 1024, "%s %s %d %.2f %.1f",
 199                  stone2str(color), coord2sstr(n->coord, b),
 200                  n->u.playouts, tree_node_get_value(u->t, -1, n->u.value),
 201                  u->t->use_extra_komi ? u->t->extra_komi : 0);
 202         return reply;
 203 }
 204
 205 static char *
 206 uct_chat(struct engine *e, struct board *b, char *cmd)
 207 {
 208         struct uct *u = e->data;
 209         static char reply[1024];
 210
 211         cmd += strspn(cmd, " \n\t");
 212         if (!strncasecmp(cmd, "winrate", 7)) {
 213                 if (!u->t)
 214                         return "no game context (yet?)";
 215                 enum stone color = u->t->root_color;
 216                 struct tree_node *n = u->t->root;
 217                 snprintf(reply, 1024, "In %d playouts at %d threads, %s %s can win with %.2f%% probability",
 218                          n->u.playouts, u->threads, stone2str(color), coord2sstr(n->coord, b),
 219                          tree_node_get_value(u->t, -1, n->u.value) * 100);
 220                 if (u->t->use_extra_komi && abs(u->t->extra_komi) >= 0.5) {
 221                         sprintf(reply + strlen(reply), ", while self-imposing extra komi %.1f",
 222                                 u->t->extra_komi);
 223                 }
 224                 strcat(reply, ".");
 225                 return reply;
 226         }
 227         return NULL;
 228 }
 229
 230 static void
 231 uct_dead_group_list(struct engine *e, struct board *b, struct move_queue *mq)
 232 {
 233         struct uct *u = e->data;
 234
 235         /* This means the game is probably over, no use pondering on. */
 236         uct_pondering_stop(u);
 237
 238         if (u->pass_all_alive)
 239                 return; // no dead groups
 240
 241         bool mock_state = false;
 242
 243         if (!u->t) {
 244                 /* No state, but we cannot just back out - we might
 245                  * have passed earlier, only assuming some stones are
 246                  * dead, and then re-connected, only to lose counting
 247                  * when all stones are assumed alive. */
 248                 uct_prepare_move(u, b, S_BLACK); assert(u->t);
 249                 mock_state = true;
 250         }
 251         /* Make sure the ownermap is well-seeded. */
 252         while (u->ownermap.playouts < GJ_MINGAMES)
 253                 uct_playout(u, b, S_BLACK, u->t);
 254         /* Show the ownermap: */
 255         if (DEBUGL(2))
 256                 board_print_custom(b, stderr, uct_printhook_ownermap);
 257
 258         dead_group_list(u, b, mq);
 259
 260         if (mock_state) {
 261                 /* Clean up the mock state in case we will receive
 262                  * a genmove; we could get a non-alternating-move
 263                  * error from uct_prepare_move() in that case otherwise. */
 264                 reset_state(u);
 265         }
 266 }
 267
 268 static void
 269 playout_policy_done(struct playout_policy *p)
 270 {
 271         if (p->done) p->done(p);
 272         if (p->data) free(p->data);
 273         free(p);
 274 }
 275
 276 static void
 277 uct_done(struct engine *e)
 278 {
 279         /* This is called on engine reset, especially when clear_board
 280          * is received and new game should begin. */
 281         struct uct *u = e->data;
 282         uct_pondering_stop(u);
 283         if (u->t) reset_state(u);
 284         free(u->ownermap.map);
 285
 286         free(u->policy);
 287         free(u->random_policy);
 288         playout_policy_done(u->playout);
 289         uct_prior_done(u->prior);
 290         joseki_done(u->jdict);
 291         pluginset_done(u->plugins);
 292 }
 293
 294
 295
 296 /* Run time-limited MCTS search on foreground. */
 297 static int
 298 uct_search(struct uct *u, struct board *b, struct time_info *ti, enum stone color, struct tree *t)
 299 {
 300         struct uct_search_state s;
 301         uct_search_start(u, b, color, t, ti, &s);
 302         if (UDEBUGL(2) && s.base_playouts > 0)
 303                 fprintf(stderr, "<pre-simulated %d games>\n", s.base_playouts);
 304
 305         /* The search tree is ctx->t. This is currently == . It is important
 306          * to reference ctx->t directly since the
 307          * thread manager will swap the tree pointer asynchronously. */
 308
 309         /* Now, just periodically poll the search tree. */
 310         /* Note that in case of TD_GAMES, threads will terminate independently
 311          * of the uct_search_check_stop() signalization. */
 312         while (1) {
 313                 time_sleep(TREE_BUSYWAIT_INTERVAL);
 314                 /* TREE_BUSYWAIT_INTERVAL should never be less than desired time, or the
 315                  * time control is broken. But if it happens to be less, we still search
 316                  * at least 100ms otherwise the move is completely random. */
 317
 318                 int i = uct_search_games(&s);
 319                 /* Print notifications etc. */
 320                 uct_search_progress(u, b, color, t, ti, &s, i);
 321                 /* Check if we should stop the search. */
 322                 if (uct_search_check_stop(u, b, color, t, ti, &s, i))
 323                         break;
 324         }
 325
 326         struct uct_thread_ctx *ctx = uct_search_stop();
 327         if (UDEBUGL(2)) tree_dump(t, u->dumpthres);
 328         if (UDEBUGL(2))
 329                 fprintf(stderr, "(avg score %f/%d value %f/%d)\n",
 330                         u->dynkomi->score.value, u->dynkomi->score.playouts,
 331                         u->dynkomi->value.value, u->dynkomi->value.playouts);
 332         if (UDEBUGL(0))
 333                 uct_progress_status(u, t, color, ctx->games);
 334
 335         u->played_own += ctx->games;
 336         return ctx->games;
 337 }
 338
 339 /* Start pondering background with @color to play. */
 340 static void
 341 uct_pondering_start(struct uct *u, struct board *b0, struct tree *t, enum stone color)
 342 {
 343         if (UDEBUGL(1))
 344                 fprintf(stderr, "Starting to ponder with color %s\n", stone2str(stone_other(color)));
 345         u->pondering = true;
 346
 347         /* We need a local board copy to ponder upon. */
 348         struct board *b = malloc2(sizeof(*b)); board_copy(b, b0);
 349
 350         /* *b0 did not have the genmove'd move played yet. */
 351         struct move m = { t->root->coord, t->root_color };
 352         int res = board_play(b, &m);
 353         assert(res >= 0);
 354         setup_dynkomi(u, b, stone_other(m.color));
 355
 356         /* Start MCTS manager thread "headless". */
 357         static struct uct_search_state s;
 358         uct_search_start(u, b, color, t, NULL, &s);
 359 }
 360
 361 /* uct_search_stop() frontend for the pondering (non-genmove) mode, and
 362  * to stop the background search for a slave in the distributed engine. */
 363 void
 364 uct_pondering_stop(struct uct *u)
 365 {
 366         if (!thread_manager_running)
 367                 return;
 368
 369         /* Stop the thread manager. */
 370         struct uct_thread_ctx *ctx = uct_search_stop();
 371         if (UDEBUGL(1)) {
 372                 if (u->pondering) fprintf(stderr, "(pondering) ");
 373                 uct_progress_status(u, ctx->t, ctx->color, ctx->games);
 374         }
 375         if (u->pondering) {
 376                 free(ctx->b);
 377                 u->pondering = false;
 378         }
 379 }
 380
 381
 382 void
 383 uct_genmove_setup(struct uct *u, struct board *b, enum stone color)
 384 {
 385         if (b->superko_violation) {
 386                 fprintf(stderr, "!!! WARNING: SUPERKO VIOLATION OCCURED BEFORE THIS MOVE\n");
 387                 fprintf(stderr, "Maybe you play with situational instead of positional superko?\n");
 388                 fprintf(stderr, "I'm going to ignore the violation, but note that I may miss\n");
 389                 fprintf(stderr, "some moves valid under this ruleset because of this.\n");
 390                 b->superko_violation = false;
 391         }
 392
 393         uct_prepare_move(u, b, color);
 394
 395         assert(u->t);
 396         u->my_color = color;
 397
 398         /* How to decide whether to use dynkomi in this game? Since we use
 399          * pondering, it's not simple "who-to-play" matter. Decide based on
 400          * the last genmove issued. */
 401         u->t->use_extra_komi = !!(u->dynkomi_mask & color);
 402         /* Moreover, we do not use extra komi at the game end - we are not
 403          * to fool ourselves at this point. */
 404         if (board_estimated_moves_left(b) <= MIN_MOVES_LEFT)
 405                 u->t->use_extra_komi = false;
 406         setup_dynkomi(u, b, color);
 407
 408         if (b->rules == RULES_JAPANESE)
 409                 u->territory_scoring = true;
 410
 411         /* Make pessimistic assumption about komi for Japanese rules to
 412          * avoid losing by 0.5 when winning by 0.5 with Chinese rules.
 413          * The rules usually give the same winner if the integer part of komi
 414          * is odd so we adjust the komi only if it is even (for a board of
 415          * odd size). We are not trying  to get an exact evaluation for rare
 416          * cases of seki. For details see http://home.snafu.de/jasiek/parity.html */
 417         if (u->territory_scoring && (((int)floor(b->komi) + board_size(b)) & 1)) {
 418                 b->komi += (color == S_BLACK ? 1.0 : -1.0);
 419                 if (UDEBUGL(0))
 420                         fprintf(stderr, "Setting komi to %.1f assuming Japanese rules\n",
 421                                 b->komi);
 422         }
 423 }
 424
 425 static coord_t *
 426 uct_genmove(struct engine *e, struct board *b, struct time_info *ti, enum stone color, bool pass_all_alive)
 427 {
 428         double start_time = time_now();
 429         struct uct *u = e->data;
 430         uct_pondering_stop(u);
 431         uct_genmove_setup(u, b, color);
 432
 433         /* Start the Monte Carlo Tree Search! */
 434         int base_playouts = u->t->root->u.playouts;
 435         int played_games = uct_search(u, b, ti, color, u->t);
 436
 437         coord_t best_coord;
 438         struct tree_node *best;
 439         best = uct_search_result(u, b, color, pass_all_alive, played_games, base_playouts, &best_coord);
 440
 441         if (UDEBUGL(2)) {
 442                 double time = time_now() - start_time + 0.000001; /* avoid divide by zero */
 443                 fprintf(stderr, "genmove in %0.2fs (%d games/s, %d games/s/thread)\n",
 444                         time, (int)(played_games/time), (int)(played_games/time/u->threads));
 445         }
 446
 447         if (!best) {
 448                 /* Pass or resign. */
 449                 reset_state(u);
 450                 return coord_copy(best_coord);
 451         }
 452         tree_promote_node(u->t, &best);
 453
 454         /* After a pass, pondering is harmful for two reasons:
 455          * (i) We might keep pondering even when the game is over.
 456          * Of course this is the case for opponent resign as well.
 457          * (ii) More importantly, the ownermap will get skewed since
 458          * the UCT will start cutting off any playouts. */
 459         if (u->pondering_opt && !is_pass(best->coord)) {
 460                 uct_pondering_start(u, b, u->t, stone_other(color));
 461         }
 462         return coord_copy(best_coord);
 463 }
 464
 465
 466 bool
 467 uct_gentbook(struct engine *e, struct board *b, struct time_info *ti, enum stone color)
 468 {
 469         struct uct *u = e->data;
 470         if (!u->t) uct_prepare_move(u, b, color);
 471         assert(u->t);
 472
 473         if (ti->dim == TD_GAMES) {
 474                 /* Don't count in games that already went into the tbook. */
 475                 ti->len.games += u->t->root->u.playouts;
 476         }
 477         uct_search(u, b, ti, color, u->t);
 478
 479         assert(ti->dim == TD_GAMES);
 480         tree_save(u->t, b, ti->len.games / 100);
 481
 482         return true;
 483 }
 484
 485 void
 486 uct_dumptbook(struct engine *e, struct board *b, enum stone color)
 487 {
 488         struct uct *u = e->data;
 489         struct tree *t = tree_init(b, color, u->fast_alloc ? u->max_tree_size : 0,
 490                          u->max_pruned_size, u->pruning_threshold, u->local_tree_aging, 0);
 491         tree_load(t, b);
 492         tree_dump(t, 0);
 493         tree_done(t);
 494 }
 495
 496
 497 floating_t
 498 uct_evaluate(struct engine *e, struct board *b, struct time_info *ti, coord_t c, enum stone color)
 499 {
 500         struct uct *u = e->data;
 501
 502         struct board b2;
 503         board_copy(&b2, b);
 504         struct move m = { c, color };
 505         int res = board_play(&b2, &m);
 506         if (res < 0)
 507                 return NAN;
 508         color = stone_other(color);
 509
 510         if (u->t) reset_state(u);
 511         uct_prepare_move(u, &b2, color);
 512         assert(u->t);
 513
 514         floating_t bestval;
 515         uct_search(u, &b2, ti, color, u->t);
 516         struct tree_node *best = u->policy->choose(u->policy, u->t->root, &b2, color, resign);
 517         if (!best) {
 518                 bestval = NAN; // the opponent has no reply!
 519         } else {
 520                 bestval = tree_node_get_value(u->t, 1, best->u.value);
 521         }
 522
 523         reset_state(u); // clean our junk
 524
 525         return isnan(bestval) ? NAN : 1.0f - bestval;
 526 }
 527
 528
 529 struct uct *
 530 uct_state_init(char *arg, struct board *b)
 531 {
 532         struct uct *u = calloc2(1, sizeof(struct uct));
 533
 534         u->debug_level = debug_level;
 535         u->gamelen = MC_GAMELEN;
 536         u->resign_threshold = 0.2;
 537         u->sure_win_threshold = 0.85;
 538         u->mercymin = 0;
 539         u->significant_threshold = 50;
 540         u->expand_p = 2;
 541         u->dumpthres = 1000;
 542         u->playout_amaf = true;
 543         u->playout_amaf_nakade = false;
 544         u->amaf_prior = false;
 545         u->max_tree_size = 3072ULL * 1048576;
 546         u->pruning_threshold = 0;
 547
 548         u->threads = 1;
 549         u->thread_model = TM_TREEVL;
 550         u->virtual_loss = 1;
 551
 552         u->fuseki_end = 20; // max time at 361*20% = 72 moves (our 36th move, still 99 to play)
 553         u->yose_start = 40; // (100-40-25)*361/100/2 = 63 moves still to play by us then
 554         u->bestr_ratio = 0.02;
 555         // 2.5 is clearly too much, but seems to compensate well for overly stern time allocations.
 556         // TODO: Further tuning and experiments with better time allocation schemes.
 557         u->best2_ratio = 2.5;
 558         u->max_maintime_ratio = 8.0;
 559
 560         u->val_scale = 0.04; u->val_points = 40;
 561         u->dynkomi_interval = 1000;
 562         u->dynkomi_mask = S_BLACK | S_WHITE;
 563
 564         u->tenuki_d = 4;
 565         u->local_tree_aging = 80;
 566         u->local_tree_allseq = 1;
 567         u->local_tree_depth_decay = 1.5;
 568
 569         u->plugins = pluginset_init(b);
 570
 571         u->jdict = joseki_load(b->size);
 572
 573         if (arg) {
 574                 char *optspec, *next = arg;
 575                 while (*next) {
 576                         optspec = next;
 577                         next += strcspn(next, ",");
 578                         if (*next) { *next++ = 0; } else { *next = 0; }
 579
 580                         char *optname = optspec;
 581                         char *optval = strchr(optspec, '=');
 582                         if (optval) *optval++ = 0;
 583
 584                         /** Basic options */
 585
 586                         if (!strcasecmp(optname, "debug")) {
 587                                 if (optval)
 588                                         u->debug_level = atoi(optval);
 589                                 else
 590                                         u->debug_level++;
 591                         } else if (!strcasecmp(optname, "dumpthres") && optval) {
 592                                 /* When dumping the UCT tree on output, include
 593                                  * nodes with at least this many playouts.
 594                                  * (This value is re-scaled "intelligently"
 595                                  * in case of very large trees.) */
 596                                 u->dumpthres = atoi(optval);
 597                         } else if (!strcasecmp(optname, "resign_threshold") && optval) {
 598                                 /* Resign when this ratio of games is lost
 599                                  * after GJ_MINGAMES sample is taken. */
 600                                 u->resign_threshold = atof(optval);
 601                         } else if (!strcasecmp(optname, "sure_win_threshold") && optval) {
 602                                 /* Stop reading when this ratio of games is won
 603                                  * after PLAYOUT_EARLY_BREAK_MIN sample is
 604                                  * taken. (Prevents stupid time losses,
 605                                  * friendly to human opponents.) */
 606                                 u->sure_win_threshold = atof(optval);
 607                         } else if (!strcasecmp(optname, "force_seed") && optval) {
 608                                 /* Set RNG seed at the tree setup. */
 609                                 u->force_seed = atoi(optval);
 610                         } else if (!strcasecmp(optname, "no_tbook")) {
 611                                 /* Disable UCT opening tbook. */
 612                                 u->no_tbook = true;
 613                         } else if (!strcasecmp(optname, "pass_all_alive")) {
 614                                 /* Whether to consider passing only after all
 615                                  * dead groups were removed from the board;
 616                                  * this is like all genmoves are in fact
 617                                  * kgs-genmove_cleanup. */
 618                                 u->pass_all_alive = !optval || atoi(optval);
 619                         } else if (!strcasecmp(optname, "territory_scoring")) {
 620                                 /* Use territory scoring (default is area scoring).
 621                                  * An explicit kgs-rules command overrides this. */
 622                                 u->territory_scoring = !optval || atoi(optval);
 623                         } else if (!strcasecmp(optname, "banner") && optval) {
 624                                 /* Additional banner string. This must come as the
 625                                  * last engine parameter. */
 626                                 if (*next) *--next = ',';
 627                                 u->banner = strdup(optval);
 628                                 break;
 629                         } else if (!strcasecmp(optname, "plugin") && optval) {
 630                                 /* Load an external plugin; filename goes before the colon,
 631                                  * extra arguments after the colon. */
 632                                 char *pluginarg = strchr(optval, ':');
 633                                 if (pluginarg)
 634                                         *pluginarg++ = 0;
 635                                 plugin_load(u->plugins, optval, pluginarg);
 636
 637                         /** UCT behavior and policies */
 638
 639                         } else if ((!strcasecmp(optname, "policy")
 640                                 /* Node selection policy. ucb1amaf is the
 641                                  * default policy implementing RAVE, while
 642                                  * ucb1 is the simple exploration/exploitation
 643                                  * policy. Policies can take further extra
 644                                  * options. */
 645                                     || !strcasecmp(optname, "random_policy")) && optval) {
 646                                 /* A policy to be used randomly with small
 647                                  * chance instead of the default policy. */
 648                                 char *policyarg = strchr(optval, ':');
 649                                 struct uct_policy **p = !strcasecmp(optname, "policy") ? &u->policy : &u->random_policy;
 650                                 if (policyarg)
 651                                         *policyarg++ = 0;
 652                                 if (!strcasecmp(optval, "ucb1")) {
 653                                         *p = policy_ucb1_init(u, policyarg);
 654                                 } else if (!strcasecmp(optval, "ucb1amaf")) {
 655                                         *p = policy_ucb1amaf_init(u, policyarg);
 656                                 } else {
 657                                         fprintf(stderr, "UCT: Invalid tree policy %s\n", optval);
 658                                         exit(1);
 659                                 }
 660                         } else if (!strcasecmp(optname, "playout") && optval) {
 661                                 /* Random simulation (playout) policy.
 662                                  * moggy is the default policy with large
 663                                  * amount of domain-specific knowledge and
 664                                  * heuristics. light is a simple uniformly
 665                                  * random move selection policy. */
 666                                 char *playoutarg = strchr(optval, ':');
 667                                 if (playoutarg)
 668                                         *playoutarg++ = 0;
 669                                 if (!strcasecmp(optval, "moggy")) {
 670                                         u->playout = playout_moggy_init(playoutarg, b, u->jdict);
 671                                 } else if (!strcasecmp(optval, "light")) {
 672                                         u->playout = playout_light_init(playoutarg, b);
 673                                 } else {
 674                                         fprintf(stderr, "UCT: Invalid playout policy %s\n", optval);
 675                                         exit(1);
 676                                 }
 677                         } else if (!strcasecmp(optname, "prior") && optval) {
 678                                 /* Node priors policy. When expanding a node,
 679                                  * it will seed node values heuristically
 680                                  * (most importantly, based on playout policy
 681                                  * opinion, but also with regard to other
 682                                  * things). See uct/prior.c for details.
 683                                  * Use prior=eqex=0 to disable priors. */
 684                                 u->prior = uct_prior_init(optval, b);
 685                         } else if (!strcasecmp(optname, "mercy") && optval) {
 686                                 /* Minimal difference of black/white captures
 687                                  * to stop playout - "Mercy Rule". Speeds up
 688                                  * hopeless playouts at the expense of some
 689                                  * accuracy. */
 690                                 u->mercymin = atoi(optval);
 691                         } else if (!strcasecmp(optname, "gamelen") && optval) {
 692                                 /* Maximum length of single simulation
 693                                  * in moves. */
 694                                 u->gamelen = atoi(optval);
 695                         } else if (!strcasecmp(optname, "expand_p") && optval) {
 696                                 /* Expand UCT nodes after it has been
 697                                  * visited this many times. */
 698                                 u->expand_p = atoi(optval);
 699                         } else if (!strcasecmp(optname, "random_policy_chance") && optval) {
 700                                 /* If specified (N), with probability 1/N, random_policy policy
 701                                  * descend is used instead of main policy descend; useful
 702                                  * if specified policy (e.g. UCB1AMAF) can make unduly biased
 703                                  * choices sometimes, you can fall back to e.g.
 704                                  * random_policy=UCB1. */
 705                                 u->random_policy_chance = atoi(optval);
 706
 707                         /** General AMAF behavior */
 708                         /* (Only relevant if the policy supports AMAF.
 709                          * More variables can be tuned as policy
 710                          * parameters.) */
 711
 712                         } else if (!strcasecmp(optname, "playout_amaf")) {
 713                                 /* Whether to include random playout moves in
 714                                  * AMAF as well. (Otherwise, only tree moves
 715                                  * are included in AMAF. Of course makes sense
 716                                  * only in connection with an AMAF policy.) */
 717                                 /* with-without: 55.5% (+-4.1) */
 718                                 if (optval && *optval == '0')
 719                                         u->playout_amaf = false;
 720                                 else
 721                                         u->playout_amaf = true;
 722                         } else if (!strcasecmp(optname, "playout_amaf_nakade")) {
 723                                 /* Whether to include nakade moves from playouts
 724                                  * in the AMAF statistics; this tends to nullify
 725                                  * the playout_amaf effect by adding too much
 726                                  * noise. */
 727                                 if (optval && *optval == '0')
 728                                         u->playout_amaf_nakade = false;
 729                                 else
 730                                         u->playout_amaf_nakade = true;
 731                         } else if (!strcasecmp(optname, "playout_amaf_cutoff") && optval) {
 732                                 /* Keep only first N% of playout stage AMAF
 733                                  * information. */
 734                                 u->playout_amaf_cutoff = atoi(optval);
 735                         } else if (!strcasecmp(optname, "amaf_prior") && optval) {
 736                                 /* In node policy, consider prior values
 737                                  * part of the real result term or part
 738                                  * of the AMAF term? */
 739                                 u->amaf_prior = atoi(optval);
 740
 741                         /** Performance and memory management */
 742
 743                         } else if (!strcasecmp(optname, "threads") && optval) {
 744                                 /* By default, Pachi will run with only single
 745                                  * tree search thread! */
 746                                 u->threads = atoi(optval);
 747                         } else if (!strcasecmp(optname, "thread_model") && optval) {
 748                                 if (!strcasecmp(optval, "tree")) {
 749                                         /* Tree parallelization - all threads
 750                                          * grind on the same tree. */
 751                                         u->thread_model = TM_TREE;
 752                                         u->virtual_loss = 0;
 753                                 } else if (!strcasecmp(optval, "treevl")) {
 754                                         /* Tree parallelization, but also
 755                                          * with virtual losses - this discou-
 756                                          * rages most threads choosing the
 757                                          * same tree branches to read. */
 758                                         u->thread_model = TM_TREEVL;
 759                                 } else {
 760                                         fprintf(stderr, "UCT: Invalid thread model %s\n", optval);
 761                                         exit(1);
 762                                 }
 763                         } else if (!strcasecmp(optname, "virtual_loss")) {
 764                                 /* Number of virtual losses added before evaluating a node. */
 765                                 u->virtual_loss = !optval || atoi(optval);
 766                         } else if (!strcasecmp(optname, "pondering")) {
 767                                 /* Keep searching even during opponent's turn. */
 768                                 u->pondering_opt = !optval || atoi(optval);
 769                         } else if (!strcasecmp(optname, "max_tree_size") && optval) {
 770                                 /* Maximum amount of memory [MiB] consumed by the move tree.
 771                                  * For fast_alloc it includes the temp tree used for pruning.
 772                                  * Default is 3072 (3 GiB). */
 773                                 u->max_tree_size = atol(optval) * 1048576;
 774                         } else if (!strcasecmp(optname, "fast_alloc")) {
 775                                 u->fast_alloc = !optval || atoi(optval);
 776                         } else if (!strcasecmp(optname, "pruning_threshold") && optval) {
 777                                 /* Force pruning at beginning of a move if the tree consumes
 778                                  * more than this [MiB]. Default is 10% of max_tree_size.
 779                                  * Increase to reduce pruning time overhead if memory is plentiful.
 780                                  * This option is meaningful only for fast_alloc. */
 781                                 u->pruning_threshold = atol(optval) * 1048576;
 782
 783                         /** Time control */
 784
 785                         } else if (!strcasecmp(optname, "best2_ratio") && optval) {
 786                                 /* If set, prolong simulating while
 787                                  * first_best/second_best playouts ratio
 788                                  * is less than best2_ratio. */
 789                                 u->best2_ratio = atof(optval);
 790                         } else if (!strcasecmp(optname, "bestr_ratio") && optval) {
 791                                 /* If set, prolong simulating while
 792                                  * best,best_best_child values delta
 793                                  * is more than bestr_ratio. */
 794                                 u->bestr_ratio = atof(optval);
 795                         } else if (!strcasecmp(optname, "max_maintime_ratio") && optval) {
 796                                 /* If set and while not in byoyomi, prolong simulating no more than
 797                                  * max_maintime_ratio times the normal desired thinking time. */
 798                                 u->max_maintime_ratio = atof(optval);
 799                         } else if (!strcasecmp(optname, "fuseki_end") && optval) {
 800                                 /* At the very beginning it's not worth thinking
 801                                  * too long because the playout evaluations are
 802                                  * very noisy. So gradually increase the thinking
 803                                  * time up to maximum when fuseki_end percent
 804                                  * of the board has been played.
 805                                  * This only applies if we are not in byoyomi. */
 806                                 u->fuseki_end = atoi(optval);
 807                         } else if (!strcasecmp(optname, "yose_start") && optval) {
 808                                 /* When yose_start percent of the board has been
 809                                  * played, or if we are in byoyomi, stop spending
 810                                  * more time and spread the remaining time
 811                                  * uniformly.
 812                                  * Between fuseki_end and yose_start, we spend
 813                                  * a constant proportion of the remaining time
 814                                  * on each move. (yose_start should actually
 815                                  * be much earlier than when real yose start,
 816                                  * but "yose" is a good short name to convey
 817                                  * the idea.) */
 818                                 u->yose_start = atoi(optval);
 819
 820                         /** Dynamic komi */
 821
 822                         } else if (!strcasecmp(optname, "dynkomi") && optval) {
 823                                 /* Dynamic komi approach; there are multiple
 824                                  * ways to adjust komi dynamically throughout
 825                                  * play. We currently support two: */
 826                                 char *dynkomiarg = strchr(optval, ':');
 827                                 if (dynkomiarg)
 828                                         *dynkomiarg++ = 0;
 829                                 if (!strcasecmp(optval, "none")) {
 830                                         u->dynkomi = uct_dynkomi_init_none(u, dynkomiarg, b);
 831                                 } else if (!strcasecmp(optval, "linear")) {
 832                                         /* You should set dynkomi_mask=1
 833                                          * since this doesn't work well
 834                                          * for white handicaps! */
 835                                         u->dynkomi = uct_dynkomi_init_linear(u, dynkomiarg, b);
 836                                 } else if (!strcasecmp(optval, "adaptive")) {
 837                                         /* There are many more knobs to
 838                                          * crank - see uct/dynkomi.c. */
 839                                         u->dynkomi = uct_dynkomi_init_adaptive(u, dynkomiarg, b);
 840                                 } else {
 841                                         fprintf(stderr, "UCT: Invalid dynkomi mode %s\n", optval);
 842                                         exit(1);
 843                                 }
 844                         } else if (!strcasecmp(optname, "dynkomi_mask") && optval) {
 845                                 /* Bitmask of colors the player must be
 846                                  * for dynkomi be applied; you may want
 847                                  * to use dynkomi_mask=3 to allow dynkomi
 848                                  * even in games where Pachi is white. */
 849                                 u->dynkomi_mask = atoi(optval);
 850                         } else if (!strcasecmp(optname, "dynkomi_interval") && optval) {
 851                                 /* If non-zero, re-adjust dynamic komi
 852                                  * throughout a single genmove reading,
 853                                  * roughly every N simulations. */
 854                                 /* XXX: Does not work with tree
 855                                  * parallelization. */
 856                                 u->dynkomi_interval = atoi(optval);
 857
 858                         /** Node value result scaling */
 859
 860                         } else if (!strcasecmp(optname, "val_scale") && optval) {
 861                                 /* How much of the game result value should be
 862                                  * influenced by win size. Zero means it isn't. */
 863                                 u->val_scale = atof(optval);
 864                         } else if (!strcasecmp(optname, "val_points") && optval) {
 865                                 /* Maximum size of win to be scaled into game
 866                                  * result value. Zero means boardsize^2. */
 867                                 u->val_points = atoi(optval) * 2; // result values are doubled
 868                         } else if (!strcasecmp(optname, "val_extra")) {
 869                                 /* If false, the score coefficient will be simply
 870                                  * added to the value, instead of scaling the result
 871                                  * coefficient because of it. */
 872                                 u->val_extra = !optval || atoi(optval);
 873
 874                         /** Local trees */
 875                         /* (Purely experimental. Does not work - yet!) */
 876
 877                         } else if (!strcasecmp(optname, "local_tree")) {
 878                                 /* Whether to bias exploration by local tree values. */
 879                                 u->local_tree = !optval || atoi(optval);
 880                         } else if (!strcasecmp(optname, "tenuki_d") && optval) {
 881                                 /* Tenuki distance at which to break the local tree. */
 882                                 u->tenuki_d = atoi(optval);
 883                                 if (u->tenuki_d > TREE_NODE_D_MAX + 1) {
 884                                         fprintf(stderr, "uct: tenuki_d must not be larger than TREE_NODE_D_MAX+1 %d\n", TREE_NODE_D_MAX + 1);
 885                                         exit(1);
 886                                 }
 887                         } else if (!strcasecmp(optname, "local_tree_aging") && optval) {
 888                                 /* How much to reduce local tree values between moves. */
 889                                 u->local_tree_aging = atof(optval);
 890                         } else if (!strcasecmp(optname, "local_tree_depth_decay") && optval) {
 891                                 /* With value x>0, during the descent the node
 892                                  * contributes 1/x^depth playouts in
 893                                  * the local tree. I.e., with x>1, nodes more
 894                                  * distant from local situation contribute more
 895                                  * than nodes near the root. */
 896                                 u->local_tree_depth_decay = atof(optval);
 897                         } else if (!strcasecmp(optname, "local_tree_allseq")) {
 898                                 /* If disabled, only complete sequences are stored
 899                                  * in the local tree. If this is on, also
 900                                  * subsequences starting at each move are stored. */
 901                                 u->local_tree_allseq = !optval || atoi(optval);
 902                         } else if (!strcasecmp(optname, "local_tree_neival")) {
 903                                 /* If disabled, local node value is not
 904                                  * computed just based on terminal status
 905                                  * of the coordinate, but also its neighbors. */
 906                                 u->local_tree_neival = !optval || atoi(optval);
 907
 908                         /** Other heuristics */
 909                         } else if (!strcasecmp(optname, "significant_threshold") && optval) {
 910                                 /* Some heuristics (XXX: none in mainline) rely
 911                                  * on the knowledge of the last "significant"
 912                                  * node in the descent. Such a node is
 913                                  * considered reasonably trustworthy to carry
 914                                  * some meaningful information in the values
 915                                  * of the node and its children. */
 916                                 u->significant_threshold = atoi(optval);
 917
 918                         /** Distributed engine slaves setup */
 919
 920                         } else if (!strcasecmp(optname, "slave")) {
 921                                 /* Act as slave for the distributed engine. */
 922                                 u->slave = !optval || atoi(optval);
 923                         } else if (!strcasecmp(optname, "shared_nodes") && optval) {
 924                                 /* Share at most shared_nodes between master and slave at each genmoves.
 925                                  * Must use the same value in master and slaves. */
 926                                 u->shared_nodes = atoi(optval);
 927                         } else if (!strcasecmp(optname, "shared_levels") && optval) {
 928                                 /* Share only nodes of level <= shared_levels. */
 929                                 u->shared_levels = atoi(optval);
 930                         } else if (!strcasecmp(optname, "stats_hbits") && optval) {
 931                                 /* Set hash table size to 2^stats_hbits for the shared stats. */
 932                                 u->stats_hbits = atoi(optval);
 933
 934                         } else {
 935                                 fprintf(stderr, "uct: Invalid engine argument %s or missing value\n", optname);
 936                                 exit(1);
 937                         }
 938                 }
 939         }
 940
 941         if (!u->policy)
 942                 u->policy = policy_ucb1amaf_init(u, NULL);
 943
 944         if (!!u->random_policy_chance ^ !!u->random_policy) {
 945                 fprintf(stderr, "uct: Only one of random_policy and random_policy_chance is set\n");
 946                 exit(1);
 947         }
 948
 949         if (!u->local_tree) {
 950                 /* No ltree aging. */
 951                 u->local_tree_aging = 1.0f;
 952         }
 953
 954         if (u->fast_alloc) {
 955                 if (u->pruning_threshold < u->max_tree_size / 10)
 956                         u->pruning_threshold = u->max_tree_size / 10;
 957                 if (u->pruning_threshold > u->max_tree_size / 2)
 958                         u->pruning_threshold = u->max_tree_size / 2;
 959
 960                 /* Limit pruning temp space to 20% of memory. Beyond this we discard
 961                  * the nodes and recompute them at the next move if necessary. */
 962                 u->max_pruned_size = u->max_tree_size / 5;
 963                 u->max_tree_size -= u->max_pruned_size;
 964         } else {
 965                 /* Reserve 5% memory in case the background free() are slower
 966                  * than the concurrent allocations. */
 967                 u->max_tree_size -= u->max_tree_size / 20;
 968         }
 969
 970         if (!u->prior)
 971                 u->prior = uct_prior_init(NULL, b);
 972
 973         if (!u->playout)
 974                 u->playout = playout_moggy_init(NULL, b, u->jdict);
 975         if (!u->playout->debug_level)
 976                 u->playout->debug_level = u->debug_level;
 977
 978         u->ownermap.map = malloc2(board_size2(b) * sizeof(u->ownermap.map[0]));
 979
 980         if (u->slave) {
 981                 if (!u->stats_hbits) u->stats_hbits = DEFAULT_STATS_HBITS;
 982                 if (!u->shared_nodes) u->shared_nodes = DEFAULT_SHARED_NODES;
 983                 assert(u->shared_levels * board_bits2(b) <= 8 * (int)sizeof(path_t));
 984         }
 985
 986         if (!u->dynkomi)
 987                 u->dynkomi = uct_dynkomi_init_adaptive(u, NULL, b);
 988
 989         /* Some things remain uninitialized for now - the opening tbook
 990          * is not loaded and the tree not set up. */
 991         /* This will be initialized in setup_state() at the first move
 992          * received/requested. This is because right now we are not aware
 993          * about any komi or handicap setup and such. */
 994
 995         return u;
 996 }
 997
 998 struct engine *
 999 engine_uct_init(char *arg, struct board *b)
1000 {
1001         struct uct *u = uct_state_init(arg, b);
1002         struct engine *e = calloc2(1, sizeof(struct engine));
1003         e->name = "UCT Engine";
1004         e->printhook = uct_printhook_ownermap;
1005         e->notify_play = uct_notify_play;
1006         e->chat = uct_chat;
1007         e->undo = uct_undo;
1008         e->result = uct_result;
1009         e->genmove = uct_genmove;
1010         e->genmoves = uct_genmoves;
1011         e->dead_group_list = uct_dead_group_list;
1012         e->done = uct_done;
1013         e->data = u;
1014         if (u->slave)
1015                 e->notify = uct_notify;
1016
1017         const char banner[] = "I'm playing UCT. When I'm losing, I will resign, "
1018                 "if I think I win, I play until you pass. "
1019                 "Anyone can send me 'winrate' in private chat to get my assessment of the position.";
1020         if (!u->banner) u->banner = "";
1021         e->comment = malloc2(sizeof(banner) + strlen(u->banner) + 1);
1022         sprintf(e->comment, "%s %s", banner, u->banner);
1023
1024         return e;
1025 }