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/elo.h"
  18 #include "playout/moggy.h"
  19 #include "playout/light.h"
  20 #include "tactics/util.h"
  21 #include "timeinfo.h"
  22 #include "uct/dynkomi.h"
  23 #include "uct/internal.h"
  24 #include "uct/plugins.h"
  25 #include "uct/prior.h"
  26 #include "uct/search.h"
  27 #include "uct/slave.h"
  28 #include "uct/tree.h"
  29 #include "uct/uct.h"
  30 #include "uct/walk.h"
  31
  32 struct uct_policy *policy_ucb1_init(struct uct *u, char *arg);
  33 struct uct_policy *policy_ucb1amaf_init(struct uct *u, char *arg);
  34 static void uct_pondering_start(struct uct *u, struct board *b0, struct tree *t, enum stone color);
  35
  36 /* Maximal simulation length. */
  37 #define MC_GAMELEN      MAX_GAMELEN
  38
  39
  40 static void
  41 setup_state(struct uct *u, struct board *b, enum stone color)
  42 {
  43         u->t = tree_init(b, color, u->fast_alloc ? u->max_tree_size : 0,
  44                          u->max_pruned_size, u->pruning_threshold, u->local_tree_aging, u->stats_hbits);
  45         if (u->force_seed)
  46                 fast_srandom(u->force_seed);
  47         if (UDEBUGL(0))
  48                 fprintf(stderr, "Fresh board with random seed %lu\n", fast_getseed());
  49         //board_print(b, stderr);
  50         if (!u->no_tbook && b->moves == 0) {
  51                 assert(color == S_BLACK);
  52                 tree_load(u->t, b);
  53         }
  54 }
  55
  56 static void
  57 reset_state(struct uct *u)
  58 {
  59         assert(u->t);
  60         tree_done(u->t); u->t = NULL;
  61 }
  62
  63 static void
  64 setup_dynkomi(struct uct *u, struct board *b, enum stone to_play)
  65 {
  66         if (u->t->use_extra_komi && !u->pondering && u->dynkomi->permove)
  67                 u->t->extra_komi = u->dynkomi->permove(u->dynkomi, b, u->t);
  68         else if (!u->t->use_extra_komi)
  69                 u->t->extra_komi = 0;
  70 }
  71
  72 void
  73 uct_prepare_move(struct uct *u, struct board *b, enum stone color)
  74 {
  75         if (u->t) {
  76                 /* Verify that we have sane state. */
  77                 assert(b->es == u);
  78                 assert(u->t && b->moves);
  79                 if (color != stone_other(u->t->root_color)) {
  80                         fprintf(stderr, "Fatal: Non-alternating play detected %d %d\n",
  81                                 color, u->t->root_color);
  82                         exit(1);
  83                 }
  84                 uct_htable_reset(u->t);
  85
  86         } else {
  87                 /* We need fresh state. */
  88                 b->es = u;
  89                 setup_state(u, b, color);
  90         }
  91
  92         u->ownermap.playouts = 0;
  93         memset(u->ownermap.map, 0, board_size2(b) * sizeof(u->ownermap.map[0]));
  94         u->played_own = u->played_all = 0;
  95 }
  96
  97 static void
  98 dead_group_list(struct uct *u, struct board *b, struct move_queue *mq)
  99 {
 100         struct group_judgement gj;
 101         gj.thres = GJ_THRES;
 102         gj.gs = alloca(board_size2(b) * sizeof(gj.gs[0]));
 103         board_ownermap_judge_group(b, &u->ownermap, &gj);
 104         groups_of_status(b, &gj, GS_DEAD, mq);
 105 }
 106
 107 bool
 108 uct_pass_is_safe(struct uct *u, struct board *b, enum stone color, bool pass_all_alive)
 109 {
 110         if (u->ownermap.playouts < GJ_MINGAMES)
 111                 return false;
 112
 113         struct move_queue mq = { .moves = 0 };
 114         dead_group_list(u, b, &mq);
 115         if (pass_all_alive && mq.moves > 0)
 116                 return false; // We need to remove some dead groups first.
 117         return pass_is_safe(b, color, &mq);
 118 }
 119
 120 static char *
 121 uct_printhook_ownermap(struct board *board, coord_t c, char *s, char *end)
 122 {
 123         struct uct *u = board->es;
 124         if (!u) {
 125                 strcat(s, ". ");
 126                 return s + 2;
 127         }
 128         const char chr[] = ":XO,"; // dame, black, white, unclear
 129         const char chm[] = ":xo,";
 130         char ch = chr[board_ownermap_judge_point(&u->ownermap, c, GJ_THRES)];
 131         if (ch == ',') { // less precise estimate then?
 132                 ch = chm[board_ownermap_judge_point(&u->ownermap, c, 0.67)];
 133         }
 134         s += snprintf(s, end - s, "%c ", ch);
 135         return s;
 136 }
 137
 138 static char *
 139 uct_notify_play(struct engine *e, struct board *b, struct move *m)
 140 {
 141         struct uct *u = e->data;
 142         if (!u->t) {
 143                 /* No state, create one - this is probably game beginning
 144                  * and we need to load the opening tbook right now. */
 145                 uct_prepare_move(u, b, m->color);
 146                 assert(u->t);
 147         }
 148
 149         /* Stop pondering, required by tree_promote_at() */
 150         uct_pondering_stop(u);
 151         if (UDEBUGL(2) && u->slave)
 152                 tree_dump(u->t, u->dumpthres);
 153
 154         if (is_resign(m->coord)) {
 155                 /* Reset state. */
 156                 reset_state(u);
 157                 return NULL;
 158         }
 159
 160         /* Promote node of the appropriate move to the tree root. */
 161         assert(u->t->root);
 162         if (!tree_promote_at(u->t, b, m->coord)) {
 163                 if (UDEBUGL(0))
 164                         fprintf(stderr, "Warning: Cannot promote move node! Several play commands in row?\n");
 165                 reset_state(u);
 166                 return NULL;
 167         }
 168
 169         /* If we are a slave in a distributed engine, start pondering once
 170          * we know which move we actually played. See uct_genmove() about
 171          * the check for pass. */
 172         if (u->pondering_opt && u->slave && m->color == u->my_color && !is_pass(m->coord))
 173                 uct_pondering_start(u, b, u->t, stone_other(m->color));
 174
 175         return NULL;
 176 }
 177
 178 static char *
 179 uct_result(struct engine *e, struct board *b)
 180 {
 181         struct uct *u = e->data;
 182         static char reply[1024];
 183
 184         if (!u->t)
 185                 return NULL;
 186         enum stone color = u->t->root_color;
 187         struct tree_node *n = u->t->root;
 188         snprintf(reply, 1024, "%s %s %d %.2f %.1f",
 189                  stone2str(color), coord2sstr(n->coord, b),
 190                  n->u.playouts, tree_node_get_value(u->t, -1, n->u.value),
 191                  u->t->use_extra_komi ? u->t->extra_komi : 0);
 192         return reply;
 193 }
 194
 195 static char *
 196 uct_chat(struct engine *e, struct board *b, char *cmd)
 197 {
 198         struct uct *u = e->data;
 199         static char reply[1024];
 200
 201         cmd += strspn(cmd, " \n\t");
 202         if (!strncasecmp(cmd, "winrate", 7)) {
 203                 if (!u->t)
 204                         return "no game context (yet?)";
 205                 enum stone color = u->t->root_color;
 206                 struct tree_node *n = u->t->root;
 207                 snprintf(reply, 1024, "In %d playouts at %d threads, %s %s can win with %.2f%% probability",
 208                          n->u.playouts, u->threads, stone2str(color), coord2sstr(n->coord, b),
 209                          tree_node_get_value(u->t, -1, n->u.value) * 100);
 210                 if (u->t->use_extra_komi && abs(u->t->extra_komi) >= 0.5) {
 211                         sprintf(reply + strlen(reply), ", while self-imposing extra komi %.1f",
 212                                 u->t->extra_komi);
 213                 }
 214                 strcat(reply, ".");
 215                 return reply;
 216         }
 217         return NULL;
 218 }
 219
 220 static void
 221 uct_dead_group_list(struct engine *e, struct board *b, struct move_queue *mq)
 222 {
 223         struct uct *u = e->data;
 224
 225         /* This means the game is probably over, no use pondering on. */
 226         uct_pondering_stop(u);
 227
 228         if (u->pass_all_alive)
 229                 return; // no dead groups
 230
 231         bool mock_state = false;
 232
 233         if (!u->t) {
 234                 /* No state, but we cannot just back out - we might
 235                  * have passed earlier, only assuming some stones are
 236                  * dead, and then re-connected, only to lose counting
 237                  * when all stones are assumed alive. */
 238                 uct_prepare_move(u, b, S_BLACK); assert(u->t);
 239                 mock_state = true;
 240         }
 241         /* Make sure the ownermap is well-seeded. */
 242         while (u->ownermap.playouts < GJ_MINGAMES)
 243                 uct_playout(u, b, S_BLACK, u->t);
 244         /* Show the ownermap: */
 245         if (DEBUGL(2))
 246                 board_print_custom(b, stderr, uct_printhook_ownermap);
 247
 248         dead_group_list(u, b, mq);
 249
 250         if (mock_state) {
 251                 /* Clean up the mock state in case we will receive
 252                  * a genmove; we could get a non-alternating-move
 253                  * error from uct_prepare_move() in that case otherwise. */
 254                 reset_state(u);
 255         }
 256 }
 257
 258 static void
 259 playout_policy_done(struct playout_policy *p)
 260 {
 261         if (p->done) p->done(p);
 262         if (p->data) free(p->data);
 263         free(p);
 264 }
 265
 266 static void
 267 uct_done(struct engine *e)
 268 {
 269         /* This is called on engine reset, especially when clear_board
 270          * is received and new game should begin. */
 271         struct uct *u = e->data;
 272         uct_pondering_stop(u);
 273         if (u->t) reset_state(u);
 274         free(u->ownermap.map);
 275
 276         free(u->policy);
 277         free(u->random_policy);
 278         playout_policy_done(u->playout);
 279         uct_prior_done(u->prior);
 280         joseki_done(u->jdict);
 281         pluginset_done(u->plugins);
 282 }
 283
 284
 285
 286 /* Run time-limited MCTS search on foreground. */
 287 static int
 288 uct_search(struct uct *u, struct board *b, struct time_info *ti, enum stone color, struct tree *t)
 289 {
 290         struct uct_search_state s;
 291         uct_search_start(u, b, color, t, ti, &s);
 292         if (UDEBUGL(2) && s.base_playouts > 0)
 293                 fprintf(stderr, "<pre-simulated %d games>\n", s.base_playouts);
 294
 295         /* The search tree is ctx->t. This is currently == . It is important
 296          * to reference ctx->t directly since the
 297          * thread manager will swap the tree pointer asynchronously. */
 298
 299         /* Now, just periodically poll the search tree. */
 300         /* Note that in case of TD_GAMES, threads will terminate independently
 301          * of the uct_search_check_stop() signalization. */
 302         while (1) {
 303                 time_sleep(TREE_BUSYWAIT_INTERVAL);
 304                 /* TREE_BUSYWAIT_INTERVAL should never be less than desired time, or the
 305                  * time control is broken. But if it happens to be less, we still search
 306                  * at least 100ms otherwise the move is completely random. */
 307
 308                 int i = uct_search_games(&s);
 309                 /* Print notifications etc. */
 310                 uct_search_progress(u, b, color, t, ti, &s, i);
 311                 /* Check if we should stop the search. */
 312                 if (uct_search_check_stop(u, b, color, t, ti, &s, i))
 313                         break;
 314         }
 315
 316         struct uct_thread_ctx *ctx = uct_search_stop();
 317         if (UDEBUGL(2)) tree_dump(t, u->dumpthres);
 318         if (UDEBUGL(2))
 319                 fprintf(stderr, "(avg score %f/%d value %f/%d)\n",
 320                         u->dynkomi->score.value, u->dynkomi->score.playouts,
 321                         u->dynkomi->value.value, u->dynkomi->value.playouts);
 322         if (UDEBUGL(0))
 323                 uct_progress_status(u, t, color, ctx->games);
 324
 325         u->played_own += ctx->games;
 326         return ctx->games;
 327 }
 328
 329 /* Start pondering background with @color to play. */
 330 static void
 331 uct_pondering_start(struct uct *u, struct board *b0, struct tree *t, enum stone color)
 332 {
 333         if (UDEBUGL(1))
 334                 fprintf(stderr, "Starting to ponder with color %s\n", stone2str(stone_other(color)));
 335         u->pondering = true;
 336
 337         /* We need a local board copy to ponder upon. */
 338         struct board *b = malloc2(sizeof(*b)); board_copy(b, b0);
 339
 340         /* *b0 did not have the genmove'd move played yet. */
 341         struct move m = { t->root->coord, t->root_color };
 342         int res = board_play(b, &m);
 343         assert(res >= 0);
 344         setup_dynkomi(u, b, stone_other(m.color));
 345
 346         /* Start MCTS manager thread "headless". */
 347         static struct uct_search_state s;
 348         uct_search_start(u, b, color, t, NULL, &s);
 349 }
 350
 351 /* uct_search_stop() frontend for the pondering (non-genmove) mode, and
 352  * to stop the background search for a slave in the distributed engine. */
 353 void
 354 uct_pondering_stop(struct uct *u)
 355 {
 356         if (!thread_manager_running)
 357                 return;
 358
 359         /* Stop the thread manager. */
 360         struct uct_thread_ctx *ctx = uct_search_stop();
 361         if (UDEBUGL(1)) {
 362                 if (u->pondering) fprintf(stderr, "(pondering) ");
 363                 uct_progress_status(u, ctx->t, ctx->color, ctx->games);
 364         }
 365         if (u->pondering) {
 366                 free(ctx->b);
 367                 u->pondering = false;
 368         }
 369 }
 370
 371
 372 void
 373 uct_genmove_setup(struct uct *u, struct board *b, enum stone color)
 374 {
 375         if (b->superko_violation) {
 376                 fprintf(stderr, "!!! WARNING: SUPERKO VIOLATION OCCURED BEFORE THIS MOVE\n");
 377                 fprintf(stderr, "Maybe you play with situational instead of positional superko?\n");
 378                 fprintf(stderr, "I'm going to ignore the violation, but note that I may miss\n");
 379                 fprintf(stderr, "some moves valid under this ruleset because of this.\n");
 380                 b->superko_violation = false;
 381         }
 382
 383         uct_prepare_move(u, b, color);
 384
 385         assert(u->t);
 386         u->my_color = color;
 387
 388         /* How to decide whether to use dynkomi in this game? Since we use
 389          * pondering, it's not simple "who-to-play" matter. Decide based on
 390          * the last genmove issued. */
 391         u->t->use_extra_komi = !!(u->dynkomi_mask & color);
 392         /* Moreover, we do not use extra komi at the game end - we are not
 393          * to fool ourselves at this point. */
 394         if (board_estimated_moves_left(b) <= MIN_MOVES_LEFT)
 395                 u->t->use_extra_komi = false;
 396         setup_dynkomi(u, b, color);
 397
 398         if (b->rules == RULES_JAPANESE)
 399                 u->territory_scoring = true;
 400
 401         /* Make pessimistic assumption about komi for Japanese rules to
 402          * avoid losing by 0.5 when winning by 0.5 with Chinese rules.
 403          * The rules usually give the same winner if the integer part of komi
 404          * is odd so we adjust the komi only if it is even (for a board of
 405          * odd size). We are not trying  to get an exact evaluation for rare
 406          * cases of seki. For details see http://home.snafu.de/jasiek/parity.html */
 407         if (u->territory_scoring && (((int)floor(b->komi) + board_size(b)) & 1)) {
 408                 b->komi += (color == S_BLACK ? 1.0 : -1.0);
 409                 if (UDEBUGL(0))
 410                         fprintf(stderr, "Setting komi to %.1f assuming Japanese rules\n",
 411                                 b->komi);
 412         }
 413 }
 414
 415 static coord_t *
 416 uct_genmove(struct engine *e, struct board *b, struct time_info *ti, enum stone color, bool pass_all_alive)
 417 {
 418         double start_time = time_now();
 419         struct uct *u = e->data;
 420         uct_pondering_stop(u);
 421         uct_genmove_setup(u, b, color);
 422
 423         /* Start the Monte Carlo Tree Search! */
 424         int base_playouts = u->t->root->u.playouts;
 425         int played_games = uct_search(u, b, ti, color, u->t);
 426
 427         coord_t best_coord;
 428         struct tree_node *best;
 429         best = uct_search_result(u, b, color, pass_all_alive, played_games, base_playouts, &best_coord);
 430
 431         if (UDEBUGL(2)) {
 432                 double time = time_now() - start_time + 0.000001; /* avoid divide by zero */
 433                 fprintf(stderr, "genmove in %0.2fs (%d games/s, %d games/s/thread)\n",
 434                         time, (int)(played_games/time), (int)(played_games/time/u->threads));
 435         }
 436
 437         if (!best) {
 438                 /* Pass or resign. */
 439                 reset_state(u);
 440                 return coord_copy(best_coord);
 441         }
 442         tree_promote_node(u->t, &best);
 443
 444         /* After a pass, pondering is harmful for two reasons:
 445          * (i) We might keep pondering even when the game is over.
 446          * Of course this is the case for opponent resign as well.
 447          * (ii) More importantly, the ownermap will get skewed since
 448          * the UCT will start cutting off any playouts. */
 449         if (u->pondering_opt && !is_pass(best->coord)) {
 450                 uct_pondering_start(u, b, u->t, stone_other(color));
 451         }
 452         return coord_copy(best_coord);
 453 }
 454
 455
 456 bool
 457 uct_gentbook(struct engine *e, struct board *b, struct time_info *ti, enum stone color)
 458 {
 459         struct uct *u = e->data;
 460         if (!u->t) uct_prepare_move(u, b, color);
 461         assert(u->t);
 462
 463         if (ti->dim == TD_GAMES) {
 464                 /* Don't count in games that already went into the tbook. */
 465                 ti->len.games += u->t->root->u.playouts;
 466         }
 467         uct_search(u, b, ti, color, u->t);
 468
 469         assert(ti->dim == TD_GAMES);
 470         tree_save(u->t, b, ti->len.games / 100);
 471
 472         return true;
 473 }
 474
 475 void
 476 uct_dumptbook(struct engine *e, struct board *b, enum stone color)
 477 {
 478         struct uct *u = e->data;
 479         struct tree *t = tree_init(b, color, u->fast_alloc ? u->max_tree_size : 0,
 480                          u->max_pruned_size, u->pruning_threshold, u->local_tree_aging, 0);
 481         tree_load(t, b);
 482         tree_dump(t, 0);
 483         tree_done(t);
 484 }
 485
 486
 487 floating_t
 488 uct_evaluate(struct engine *e, struct board *b, struct time_info *ti, coord_t c, enum stone color)
 489 {
 490         struct uct *u = e->data;
 491
 492         struct board b2;
 493         board_copy(&b2, b);
 494         struct move m = { c, color };
 495         int res = board_play(&b2, &m);
 496         if (res < 0)
 497                 return NAN;
 498         color = stone_other(color);
 499
 500         if (u->t) reset_state(u);
 501         uct_prepare_move(u, &b2, color);
 502         assert(u->t);
 503
 504         floating_t bestval;
 505         uct_search(u, &b2, ti, color, u->t);
 506         struct tree_node *best = u->policy->choose(u->policy, u->t->root, &b2, color, resign);
 507         if (!best) {
 508                 bestval = NAN; // the opponent has no reply!
 509         } else {
 510                 bestval = tree_node_get_value(u->t, 1, best->u.value);
 511         }
 512
 513         reset_state(u); // clean our junk
 514
 515         return isnan(bestval) ? NAN : 1.0f - bestval;
 516 }
 517
 518
 519 struct uct *
 520 uct_state_init(char *arg, struct board *b)
 521 {
 522         struct uct *u = calloc2(1, sizeof(struct uct));
 523         bool using_elo = false;
 524
 525         u->debug_level = debug_level;
 526         u->gamelen = MC_GAMELEN;
 527         u->resign_threshold = 0.2;
 528         u->sure_win_threshold = 0.85;
 529         u->mercymin = 0;
 530         u->significant_threshold = 50;
 531         u->expand_p = 2;
 532         u->dumpthres = 1000;
 533         u->playout_amaf = true;
 534         u->playout_amaf_nakade = false;
 535         u->amaf_prior = false;
 536         u->max_tree_size = 3072ULL * 1048576;
 537         u->pruning_threshold = 0;
 538
 539         u->threads = 1;
 540         u->thread_model = TM_TREEVL;
 541         u->virtual_loss = 1;
 542
 543         u->fuseki_end = 20; // max time at 361*20% = 72 moves (our 36th move, still 99 to play)
 544         u->yose_start = 40; // (100-40-25)*361/100/2 = 63 moves still to play by us then
 545         u->bestr_ratio = 0.02;
 546         // 2.5 is clearly too much, but seems to compensate well for overly stern time allocations.
 547         // TODO: Further tuning and experiments with better time allocation schemes.
 548         u->best2_ratio = 2.5;
 549         u->max_maintime_ratio = 3.0;
 550
 551         u->val_scale = 0.04; u->val_points = 40;
 552         u->dynkomi_interval = 1000;
 553         u->dynkomi_mask = S_BLACK | S_WHITE;
 554
 555         u->tenuki_d = 4;
 556         u->local_tree_aging = 2;
 557
 558         u->plugins = pluginset_init(b);
 559
 560         u->jdict = joseki_load(b->size);
 561
 562         if (arg) {
 563                 char *optspec, *next = arg;
 564                 while (*next) {
 565                         optspec = next;
 566                         next += strcspn(next, ",");
 567                         if (*next) { *next++ = 0; } else { *next = 0; }
 568
 569                         char *optname = optspec;
 570                         char *optval = strchr(optspec, '=');
 571                         if (optval) *optval++ = 0;
 572
 573                         /** Basic options */
 574
 575                         if (!strcasecmp(optname, "debug")) {
 576                                 if (optval)
 577                                         u->debug_level = atoi(optval);
 578                                 else
 579                                         u->debug_level++;
 580                         } else if (!strcasecmp(optname, "dumpthres") && optval) {
 581                                 /* When dumping the UCT tree on output, include
 582                                  * nodes with at least this many playouts.
 583                                  * (This value is re-scaled "intelligently"
 584                                  * in case of very large trees.) */
 585                                 u->dumpthres = atoi(optval);
 586                         } else if (!strcasecmp(optname, "resign_threshold") && optval) {
 587                                 /* Resign when this ratio of games is lost
 588                                  * after GJ_MINGAMES sample is taken. */
 589                                 u->resign_threshold = atof(optval);
 590                         } else if (!strcasecmp(optname, "sure_win_threshold") && optval) {
 591                                 /* Stop reading when this ratio of games is won
 592                                  * after PLAYOUT_EARLY_BREAK_MIN sample is
 593                                  * taken. (Prevents stupid time losses,
 594                                  * friendly to human opponents.) */
 595                                 u->sure_win_threshold = atof(optval);
 596                         } else if (!strcasecmp(optname, "force_seed") && optval) {
 597                                 /* Set RNG seed at the tree setup. */
 598                                 u->force_seed = atoi(optval);
 599                         } else if (!strcasecmp(optname, "no_tbook")) {
 600                                 /* Disable UCT opening tbook. */
 601                                 u->no_tbook = true;
 602                         } else if (!strcasecmp(optname, "pass_all_alive")) {
 603                                 /* Whether to consider passing only after all
 604                                  * dead groups were removed from the board;
 605                                  * this is like all genmoves are in fact
 606                                  * kgs-genmove_cleanup. */
 607                                 u->pass_all_alive = !optval || atoi(optval);
 608                         } else if (!strcasecmp(optname, "territory_scoring")) {
 609                                 /* Use territory scoring (default is area scoring).
 610                                  * An explicit kgs-rules command overrides this. */
 611                                 u->territory_scoring = !optval || atoi(optval);
 612                         } else if (!strcasecmp(optname, "banner") && optval) {
 613                                 /* Additional banner string. This must come as the
 614                                  * last engine parameter. */
 615                                 if (*next) *--next = ',';
 616                                 u->banner = strdup(optval);
 617                                 break;
 618                         } else if (!strcasecmp(optname, "plugin") && optval) {
 619                                 /* Load an external plugin; filename goes before the colon,
 620                                  * extra arguments after the colon. */
 621                                 char *pluginarg = strchr(optval, ':');
 622                                 if (pluginarg)
 623                                         *pluginarg++ = 0;
 624                                 plugin_load(u->plugins, optval, pluginarg);
 625
 626                         /** UCT behavior and policies */
 627
 628                         } else if ((!strcasecmp(optname, "policy")
 629                                 /* Node selection policy. ucb1amaf is the
 630                                  * default policy implementing RAVE, while
 631                                  * ucb1 is the simple exploration/exploitation
 632                                  * policy. Policies can take further extra
 633                                  * options. */
 634                                     || !strcasecmp(optname, "random_policy")) && optval) {
 635                                 /* A policy to be used randomly with small
 636                                  * chance instead of the default policy. */
 637                                 char *policyarg = strchr(optval, ':');
 638                                 struct uct_policy **p = !strcasecmp(optname, "policy") ? &u->policy : &u->random_policy;
 639                                 if (policyarg)
 640                                         *policyarg++ = 0;
 641                                 if (!strcasecmp(optval, "ucb1")) {
 642                                         *p = policy_ucb1_init(u, policyarg);
 643                                 } else if (!strcasecmp(optval, "ucb1amaf")) {
 644                                         *p = policy_ucb1amaf_init(u, policyarg);
 645                                 } else {
 646                                         fprintf(stderr, "UCT: Invalid tree policy %s\n", optval);
 647                                         exit(1);
 648                                 }
 649                         } else if (!strcasecmp(optname, "playout") && optval) {
 650                                 /* Random simulation (playout) policy.
 651                                  * moggy is the default policy with large
 652                                  * amount of domain-specific knowledge and
 653                                  * heuristics. light is a simple uniformly
 654                                  * random move selection policy. */
 655                                 char *playoutarg = strchr(optval, ':');
 656                                 if (playoutarg)
 657                                         *playoutarg++ = 0;
 658                                 if (!strcasecmp(optval, "moggy")) {
 659                                         u->playout = playout_moggy_init(playoutarg, b, u->jdict);
 660                                 } else if (!strcasecmp(optval, "light")) {
 661                                         u->playout = playout_light_init(playoutarg, b);
 662                                 } else if (!strcasecmp(optval, "elo")) {
 663                                         u->playout = playout_elo_init(playoutarg, b);
 664                                         using_elo = true;
 665                                 } else {
 666                                         fprintf(stderr, "UCT: Invalid playout policy %s\n", optval);
 667                                         exit(1);
 668                                 }
 669                         } else if (!strcasecmp(optname, "prior") && optval) {
 670                                 /* Node priors policy. When expanding a node,
 671                                  * it will seed node values heuristically
 672                                  * (most importantly, based on playout policy
 673                                  * opinion, but also with regard to other
 674                                  * things). See uct/prior.c for details.
 675                                  * Use prior=eqex=0 to disable priors. */
 676                                 u->prior = uct_prior_init(optval, b);
 677                         } else if (!strcasecmp(optname, "mercy") && optval) {
 678                                 /* Minimal difference of black/white captures
 679                                  * to stop playout - "Mercy Rule". Speeds up
 680                                  * hopeless playouts at the expense of some
 681                                  * accuracy. */
 682                                 u->mercymin = atoi(optval);
 683                         } else if (!strcasecmp(optname, "gamelen") && optval) {
 684                                 /* Maximum length of single simulation
 685                                  * in moves. */
 686                                 u->gamelen = atoi(optval);
 687                         } else if (!strcasecmp(optname, "expand_p") && optval) {
 688                                 /* Expand UCT nodes after it has been
 689                                  * visited this many times. */
 690                                 u->expand_p = atoi(optval);
 691                         } else if (!strcasecmp(optname, "random_policy_chance") && optval) {
 692                                 /* If specified (N), with probability 1/N, random_policy policy
 693                                  * descend is used instead of main policy descend; useful
 694                                  * if specified policy (e.g. UCB1AMAF) can make unduly biased
 695                                  * choices sometimes, you can fall back to e.g.
 696                                  * random_policy=UCB1. */
 697                                 u->random_policy_chance = atoi(optval);
 698
 699                         /** General AMAF behavior */
 700                         /* (Only relevant if the policy supports AMAF.
 701                          * More variables can be tuned as policy
 702                          * parameters.) */
 703
 704                         } else if (!strcasecmp(optname, "playout_amaf")) {
 705                                 /* Whether to include random playout moves in
 706                                  * AMAF as well. (Otherwise, only tree moves
 707                                  * are included in AMAF. Of course makes sense
 708                                  * only in connection with an AMAF policy.) */
 709                                 /* with-without: 55.5% (+-4.1) */
 710                                 if (optval && *optval == '0')
 711                                         u->playout_amaf = false;
 712                                 else
 713                                         u->playout_amaf = true;
 714                         } else if (!strcasecmp(optname, "playout_amaf_nakade")) {
 715                                 /* Whether to include nakade moves from playouts
 716                                  * in the AMAF statistics; this tends to nullify
 717                                  * the playout_amaf effect by adding too much
 718                                  * noise. */
 719                                 if (optval && *optval == '0')
 720                                         u->playout_amaf_nakade = false;
 721                                 else
 722                                         u->playout_amaf_nakade = true;
 723                         } else if (!strcasecmp(optname, "playout_amaf_cutoff") && optval) {
 724                                 /* Keep only first N% of playout stage AMAF
 725                                  * information. */
 726                                 u->playout_amaf_cutoff = atoi(optval);
 727                         } else if (!strcasecmp(optname, "amaf_prior") && optval) {
 728                                 /* In node policy, consider prior values
 729                                  * part of the real result term or part
 730                                  * of the AMAF term? */
 731                                 u->amaf_prior = atoi(optval);
 732
 733                         /** Performance and memory management */
 734
 735                         } else if (!strcasecmp(optname, "threads") && optval) {
 736                                 /* By default, Pachi will run with only single
 737                                  * tree search thread! */
 738                                 u->threads = atoi(optval);
 739                         } else if (!strcasecmp(optname, "thread_model") && optval) {
 740                                 if (!strcasecmp(optval, "tree")) {
 741                                         /* Tree parallelization - all threads
 742                                          * grind on the same tree. */
 743                                         u->thread_model = TM_TREE;
 744                                         u->virtual_loss = 0;
 745                                 } else if (!strcasecmp(optval, "treevl")) {
 746                                         /* Tree parallelization, but also
 747                                          * with virtual losses - this discou-
 748                                          * rages most threads choosing the
 749                                          * same tree branches to read. */
 750                                         u->thread_model = TM_TREEVL;
 751                                 } else {
 752                                         fprintf(stderr, "UCT: Invalid thread model %s\n", optval);
 753                                         exit(1);
 754                                 }
 755                         } else if (!strcasecmp(optname, "virtual_loss")) {
 756                                 /* Number of virtual losses added before evaluating a node. */
 757                                 u->virtual_loss = !optval || atoi(optval);
 758                         } else if (!strcasecmp(optname, "pondering")) {
 759                                 /* Keep searching even during opponent's turn. */
 760                                 u->pondering_opt = !optval || atoi(optval);
 761                         } else if (!strcasecmp(optname, "max_tree_size") && optval) {
 762                                 /* Maximum amount of memory [MiB] consumed by the move tree.
 763                                  * For fast_alloc it includes the temp tree used for pruning.
 764                                  * Default is 3072 (3 GiB). */
 765                                 u->max_tree_size = atol(optval) * 1048576;
 766                         } else if (!strcasecmp(optname, "fast_alloc")) {
 767                                 u->fast_alloc = !optval || atoi(optval);
 768                         } else if (!strcasecmp(optname, "pruning_threshold") && optval) {
 769                                 /* Force pruning at beginning of a move if the tree consumes
 770                                  * more than this [MiB]. Default is 10% of max_tree_size.
 771                                  * Increase to reduce pruning time overhead if memory is plentiful.
 772                                  * This option is meaningful only for fast_alloc. */
 773                                 u->pruning_threshold = atol(optval) * 1048576;
 774
 775                         /** Time control */
 776
 777                         } else if (!strcasecmp(optname, "best2_ratio") && optval) {
 778                                 /* If set, prolong simulating while
 779                                  * first_best/second_best playouts ratio
 780                                  * is less than best2_ratio. */
 781                                 u->best2_ratio = atof(optval);
 782                         } else if (!strcasecmp(optname, "bestr_ratio") && optval) {
 783                                 /* If set, prolong simulating while
 784                                  * best,best_best_child values delta
 785                                  * is more than bestr_ratio. */
 786                                 u->bestr_ratio = atof(optval);
 787                         } else if (!strcasecmp(optname, "max_maintime_ratio") && optval) {
 788                                 /* If set and while not in byoyomi, prolong simulating no more than
 789                                  * max_maintime_ratio times the normal desired thinking time. */
 790                                 u->max_maintime_ratio = atof(optval);
 791                         } else if (!strcasecmp(optname, "fuseki_end") && optval) {
 792                                 /* At the very beginning it's not worth thinking
 793                                  * too long because the playout evaluations are
 794                                  * very noisy. So gradually increase the thinking
 795                                  * time up to maximum when fuseki_end percent
 796                                  * of the board has been played.
 797                                  * This only applies if we are not in byoyomi. */
 798                                 u->fuseki_end = atoi(optval);
 799                         } else if (!strcasecmp(optname, "yose_start") && optval) {
 800                                 /* When yose_start percent of the board has been
 801                                  * played, or if we are in byoyomi, stop spending
 802                                  * more time and spread the remaining time
 803                                  * uniformly.
 804                                  * Between fuseki_end and yose_start, we spend
 805                                  * a constant proportion of the remaining time
 806                                  * on each move. (yose_start should actually
 807                                  * be much earlier than when real yose start,
 808                                  * but "yose" is a good short name to convey
 809                                  * the idea.) */
 810                                 u->yose_start = atoi(optval);
 811
 812                         /** Dynamic komi */
 813
 814                         } else if (!strcasecmp(optname, "dynkomi") && optval) {
 815                                 /* Dynamic komi approach; there are multiple
 816                                  * ways to adjust komi dynamically throughout
 817                                  * play. We currently support two: */
 818                                 char *dynkomiarg = strchr(optval, ':');
 819                                 if (dynkomiarg)
 820                                         *dynkomiarg++ = 0;
 821                                 if (!strcasecmp(optval, "none")) {
 822                                         u->dynkomi = uct_dynkomi_init_none(u, dynkomiarg, b);
 823                                 } else if (!strcasecmp(optval, "linear")) {
 824                                         /* You should set dynkomi_mask=1
 825                                          * since this doesn't work well
 826                                          * for white handicaps! */
 827                                         u->dynkomi = uct_dynkomi_init_linear(u, dynkomiarg, b);
 828                                 } else if (!strcasecmp(optval, "adaptive")) {
 829                                         /* There are many more knobs to
 830                                          * crank - see uct/dynkomi.c. */
 831                                         u->dynkomi = uct_dynkomi_init_adaptive(u, dynkomiarg, b);
 832                                 } else {
 833                                         fprintf(stderr, "UCT: Invalid dynkomi mode %s\n", optval);
 834                                         exit(1);
 835                                 }
 836                         } else if (!strcasecmp(optname, "dynkomi_mask") && optval) {
 837                                 /* Bitmask of colors the player must be
 838                                  * for dynkomi be applied; you may want
 839                                  * to use dynkomi_mask=3 to allow dynkomi
 840                                  * even in games where Pachi is white. */
 841                                 u->dynkomi_mask = atoi(optval);
 842                         } else if (!strcasecmp(optname, "dynkomi_interval") && optval) {
 843                                 /* If non-zero, re-adjust dynamic komi
 844                                  * throughout a single genmove reading,
 845                                  * roughly every N simulations. */
 846                                 /* XXX: Does not work with tree
 847                                  * parallelization. */
 848                                 u->dynkomi_interval = atoi(optval);
 849
 850                         /** Node value result scaling */
 851
 852                         } else if (!strcasecmp(optname, "val_scale") && optval) {
 853                                 /* How much of the game result value should be
 854                                  * influenced by win size. Zero means it isn't. */
 855                                 u->val_scale = atof(optval);
 856                         } else if (!strcasecmp(optname, "val_points") && optval) {
 857                                 /* Maximum size of win to be scaled into game
 858                                  * result value. Zero means boardsize^2. */
 859                                 u->val_points = atoi(optval) * 2; // result values are doubled
 860                         } else if (!strcasecmp(optname, "val_extra")) {
 861                                 /* If false, the score coefficient will be simply
 862                                  * added to the value, instead of scaling the result
 863                                  * coefficient because of it. */
 864                                 u->val_extra = !optval || atoi(optval);
 865
 866                         /** Local trees */
 867                         /* (Purely experimental. Does not work - yet!) */
 868
 869                         } else if (!strcasecmp(optname, "local_tree") && optval) {
 870                                 /* Whether to bias exploration by local tree values
 871                                  * (must be supported by the used policy).
 872                                  * 0: Don't.
 873                                  * 1: Do, value = result.
 874                                  * Try to temper the result:
 875                                  * 2: Do, value = 0.5+(result-expected)/2.
 876                                  * 3: Do, value = 0.5+bzz((result-expected)^2).
 877                                  * 4: Do, value = 0.5+sqrt(result-expected)/2. */
 878                                 u->local_tree = atoi(optval);
 879                         } else if (!strcasecmp(optname, "tenuki_d") && optval) {
 880                                 /* Tenuki distance at which to break the local tree. */
 881                                 u->tenuki_d = atoi(optval);
 882                                 if (u->tenuki_d > TREE_NODE_D_MAX + 1) {
 883                                         fprintf(stderr, "uct: tenuki_d must not be larger than TREE_NODE_D_MAX+1 %d\n", TREE_NODE_D_MAX + 1);
 884                                         exit(1);
 885                                 }
 886                         } else if (!strcasecmp(optname, "local_tree_aging") && optval) {
 887                                 /* How much to reduce local tree values between moves. */
 888                                 u->local_tree_aging = atof(optval);
 889                         } else if (!strcasecmp(optname, "local_tree_depth_decay") && optval) {
 890                                 /* With value x>0, during the descent the node
 891                                  * contributes 1/x^depth playouts in
 892                                  * the local tree. I.e., with x>1, nodes more
 893                                  * distant from local situation contribute more
 894                                  * than nodes near the root. */
 895                                 u->local_tree_depth_decay = atof(optval);
 896                         } else if (!strcasecmp(optname, "local_tree_allseq")) {
 897                                 /* By default, only complete sequences are stored
 898                                  * in the local tree. If this is on, also
 899                                  * subsequences starting at each move are stored. */
 900                                 u->local_tree_allseq = !optval || atoi(optval);
 901                         } else if (!strcasecmp(optname, "local_tree_playout")) {
 902                                 /* Whether to adjust ELO playout probability
 903                                  * distributions according to matched localtree
 904                                  * information. */
 905                                 u->local_tree_playout = !optval || atoi(optval);
 906                         } else if (!strcasecmp(optname, "local_tree_pseqroot")) {
 907                                 /* By default, when we have no sequence move
 908                                  * to suggest in-playout, we give up. If this
 909                                  * is on, we make probability distribution from
 910                                  * sequences first moves instead. */
 911                                 u->local_tree_pseqroot = !optval || atoi(optval);
 912                         } else if (!strcasecmp(optname, "local_tree_rootseqval")) {
 913                                 /* By default, expected node value is computed by
 914                                  * summing up values through the whole descent.
 915                                  * With this settings, expected node value for
 916                                  * each sequence is the value at the root of the
 917                                  * sequence. */
 918                                 u->local_tree_rootseqval = !optval || atoi(optval);
 919
 920                         /** Other heuristics */
 921                         } else if (!strcasecmp(optname, "significant_threshold") && optval) {
 922                                 /* Some heuristics (treepool) rely
 923                                  * on the knowledge of the last "significant"
 924                                  * node in the descent. Such a node is
 925                                  * considered reasonably trustworthy to carry
 926                                  * some meaningful information in the values
 927                                  * of the node and its children. */
 928                                 u->significant_threshold = atoi(optval);
 929                         } else if (!strcasecmp(optname, "treepool_chance") && optval) {
 930                                 /* Chance of applying the treepool heuristic:
 931                                  * one of the best N children of the last
 932                                  * significant node is tried on each turn
 933                                  * of the simulation. */
 934                                 /* This is in form of two numbers:
 935                                  * PREMOVE:POSTMOVE. Each is percentage
 936                                  * value, one is the chance of the move
 937                                  * tried before playout policy, one is the
 938                                  * chance of it being applied if the policy
 939                                  * has not picked anymove. */
 940                                 char *optval2 = strchr(optval, ':');
 941                                 if (!optval2) {
 942                                         fprintf(stderr, "uct: treepool_chance takes two comma-separated numbers\n");
 943                                         exit(1);
 944                                 }
 945                                 u->treepool_chance[0] = atoi(optval);
 946                                 optval = ++optval2;
 947                                 u->treepool_chance[1] = atoi(optval);
 948                         } else if (!strcasecmp(optname, "treepool_size") && optval) {
 949                                 /* Number of top significant children
 950                                  * to pick from. Too low means low effect,
 951                                  * too high means even lousy moves are
 952                                  * played. */
 953                                 u->treepool_size = atoi(optval);
 954                         } else if (!strcasecmp(optname, "treepool_type") && optval) {
 955                                 /* How to sort the children. */
 956                                 if (!strcasecmp(optval, "rave_playouts"))
 957                                         u->treepool_type = UTT_RAVE_PLAYOUTS;
 958                                 else if (!strcasecmp(optval, "rave_value"))
 959                                         u->treepool_type = UTT_RAVE_VALUE;
 960                                 else if (!strcasecmp(optval, "uct_playouts"))
 961                                         u->treepool_type = UTT_UCT_PLAYOUTS;
 962                                 else if (!strcasecmp(optval, "uct_value"))
 963                                         u->treepool_type = UTT_UCT_VALUE;
 964                                 else if (!strcasecmp(optval, "evaluate"))
 965                                         /* The proper combination of RAVE,
 966                                          * UCT and prior, as used through
 967                                          * descent. */
 968                                         u->treepool_type = UTT_EVALUATE;
 969                                 else {
 970                                         fprintf(stderr, "uct: unknown treepool_type %s\n", optval);
 971                                         exit(1);
 972                                 }
 973                         } else if (!strcasecmp(optname, "treepool_pickfactor") && optval) {
 974                                 /* Pick factor influencing children choice.
 975                                  * By default (if this is 0 or 10), coords
 976                                  * have uniform probability to be chosen;
 977                                  * otherwise, children are tried from best
 978                                  * to worst, each picked with probability
 979                                  * (1/n * pickfactor/10).
 980                                  * I.e., better children may be preferred
 981                                  * if pickfactor > 10. */
 982                                 u->treepool_pickfactor = atoi(optval);
 983
 984                         /** Distributed engine slaves setup */
 985
 986                         } else if (!strcasecmp(optname, "slave")) {
 987                                 /* Act as slave for the distributed engine. */
 988                                 u->slave = !optval || atoi(optval);
 989                         } else if (!strcasecmp(optname, "shared_nodes") && optval) {
 990                                 /* Share at most shared_nodes between master and slave at each genmoves.
 991                                  * Must use the same value in master and slaves. */
 992                                 u->shared_nodes = atoi(optval);
 993                         } else if (!strcasecmp(optname, "shared_levels") && optval) {
 994                                 /* Share only nodes of level <= shared_levels. */
 995                                 u->shared_levels = atoi(optval);
 996                         } else if (!strcasecmp(optname, "stats_hbits") && optval) {
 997                                 /* Set hash table size to 2^stats_hbits for the shared stats. */
 998                                 u->stats_hbits = atoi(optval);
 999
1000                         } else {
1001                                 fprintf(stderr, "uct: Invalid engine argument %s or missing value\n", optname);
1002                                 exit(1);
1003                         }
1004                 }
1005         }
1006
1007         if (!u->policy)
1008                 u->policy = policy_ucb1amaf_init(u, NULL);
1009
1010         if (!!u->random_policy_chance ^ !!u->random_policy) {
1011                 fprintf(stderr, "uct: Only one of random_policy and random_policy_chance is set\n");
1012                 exit(1);
1013         }
1014
1015         if (!u->local_tree) {
1016                 /* No ltree aging. */
1017                 u->local_tree_aging = 1.0f;
1018         }
1019         if (!using_elo)
1020                 u->local_tree_playout = false;
1021
1022         if (u->fast_alloc) {
1023                 if (u->pruning_threshold < u->max_tree_size / 10)
1024                         u->pruning_threshold = u->max_tree_size / 10;
1025                 if (u->pruning_threshold > u->max_tree_size / 2)
1026                         u->pruning_threshold = u->max_tree_size / 2;
1027
1028                 /* Limit pruning temp space to 20% of memory. Beyond this we discard
1029                  * the nodes and recompute them at the next move if necessary. */
1030                 u->max_pruned_size = u->max_tree_size / 5;
1031                 u->max_tree_size -= u->max_pruned_size;
1032         } else {
1033                 /* Reserve 5% memory in case the background free() are slower
1034                  * than the concurrent allocations. */
1035                 u->max_tree_size -= u->max_tree_size / 20;
1036         }
1037
1038         if (!u->prior)
1039                 u->prior = uct_prior_init(NULL, b);
1040
1041         if (!u->playout)
1042                 u->playout = playout_moggy_init(NULL, b, u->jdict);
1043         if (!u->playout->debug_level)
1044                 u->playout->debug_level = u->debug_level;
1045
1046         u->ownermap.map = malloc2(board_size2(b) * sizeof(u->ownermap.map[0]));
1047
1048         if (u->slave) {
1049                 if (!u->stats_hbits) u->stats_hbits = DEFAULT_STATS_HBITS;
1050                 if (!u->shared_nodes) u->shared_nodes = DEFAULT_SHARED_NODES;
1051                 assert(u->shared_levels * board_bits2(b) <= 8 * (int)sizeof(path_t));
1052         }
1053
1054         if (!u->dynkomi)
1055                 u->dynkomi = uct_dynkomi_init_adaptive(u, NULL, b);
1056
1057         /* Some things remain uninitialized for now - the opening tbook
1058          * is not loaded and the tree not set up. */
1059         /* This will be initialized in setup_state() at the first move
1060          * received/requested. This is because right now we are not aware
1061          * about any komi or handicap setup and such. */
1062
1063         return u;
1064 }
1065
1066 struct engine *
1067 engine_uct_init(char *arg, struct board *b)
1068 {
1069         struct uct *u = uct_state_init(arg, b);
1070         struct engine *e = calloc2(1, sizeof(struct engine));
1071         e->name = "UCT Engine";
1072         e->printhook = uct_printhook_ownermap;
1073         e->notify_play = uct_notify_play;
1074         e->chat = uct_chat;
1075         e->result = uct_result;
1076         e->genmove = uct_genmove;
1077         e->genmoves = uct_genmoves;
1078         e->dead_group_list = uct_dead_group_list;
1079         e->done = uct_done;
1080         e->data = u;
1081         if (u->slave)
1082                 e->notify = uct_notify;
1083
1084         const char banner[] = "I'm playing UCT. When I'm losing, I will resign, "
1085                 "if I think I win, I play until you pass. "
1086                 "Anyone can send me 'winrate' in private chat to get my assessment of the position.";
1087         if (!u->banner) u->banner = "";
1088         e->comment = malloc2(sizeof(banner) + strlen(u->banner) + 1);
1089         sprintf(e->comment, "%s %s", banner, u->banner);
1090
1091         return e;
1092 }