uct/uct.c

   1 #include <assert.h>
   2 #include <pthread.h>
   3 #include <signal.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <time.h>
   8
   9 #define DEBUG
  10
  11 #include "debug.h"
  12 #include "board.h"
  13 #include "gtp.h"
  14 #include "move.h"
  15 #include "mq.h"
  16 #include "playout.h"
  17 #include "playout/elo.h"
  18 #include "playout/moggy.h"
  19 #include "playout/light.h"
  20 #include "random.h"
  21 #include "timeinfo.h"
  22 #include "tactics.h"
  23 #include "uct/internal.h"
  24 #include "uct/prior.h"
  25 #include "uct/tree.h"
  26 #include "uct/uct.h"
  27 #include "uct/walk.h"
  28
  29 struct uct_policy *policy_ucb1_init(struct uct *u, char *arg);
  30 struct uct_policy *policy_ucb1amaf_init(struct uct *u, char *arg);
  31 static void uct_pondering_stop(struct uct *u);
  32
  33
  34 /* Default number of simulations to perform per move.
  35  * Note that this is now in total over all threads! (Unless TM_ROOT.) */
  36 #define MC_GAMES        80000
  37 #define MC_GAMELEN      MAX_GAMELEN
  38
  39 /* How big proportion of ownermap counts must be of one color to consider
  40  * the point sure. */
  41 #define GJ_THRES        0.8
  42 /* How many games to consider at minimum before judging groups. */
  43 #define GJ_MINGAMES     500
  44
  45 /* How often to inspect the tree from the main thread to check for playout
  46  * stop, progress reports, etc. A (struct timespec) initializer. */
  47 #define TREE_BUSYWAIT_INTERVAL { .tv_sec = 0, .tv_nsec = 100*1000000 /* 100ms */ }
  48 /* Once per how many simulations (per thread) to show a progress report line. */
  49 #define TREE_SIMPROGRESS_INTERVAL 10000
  50
  51
  52 static void
  53 setup_state(struct uct *u, struct board *b, enum stone color)
  54 {
  55         u->t = tree_init(b, color);
  56         if (u->force_seed)
  57                 fast_srandom(u->force_seed);
  58         if (UDEBUGL(0))
  59                 fprintf(stderr, "Fresh board with random seed %lu\n", fast_getseed());
  60         //board_print(b, stderr);
  61         if (!u->no_book && b->moves == 0) {
  62                 assert(color == S_BLACK);
  63                 tree_load(u->t, b);
  64         }
  65 }
  66
  67 static void
  68 reset_state(struct uct *u)
  69 {
  70         assert(u->t);
  71         tree_done(u->t); u->t = NULL;
  72 }
  73
  74 static void
  75 prepare_move(struct engine *e, struct board *b, enum stone color)
  76 {
  77         struct uct *u = e->data;
  78
  79         if (u->t) {
  80                 /* Verify that we have sane state. */
  81                 assert(b->es == u);
  82                 assert(u->t && b->moves);
  83                 if (color != stone_other(u->t->root_color)) {
  84                         fprintf(stderr, "Fatal: Non-alternating play detected %d %d\n",
  85                                 color, u->t->root_color);
  86                         exit(1);
  87                 }
  88
  89         } else {
  90                 /* We need fresh state. */
  91                 b->es = u;
  92                 setup_state(u, b, color);
  93         }
  94
  95         if (u->dynkomi && u->dynkomi > b->moves && (color & u->dynkomi_mask))
  96                 u->t->extra_komi = uct_get_extra_komi(u, b);
  97
  98         u->ownermap.playouts = 0;
  99         memset(u->ownermap.map, 0, board_size2(b) * sizeof(u->ownermap.map[0]));
 100 }
 101
 102 static void
 103 dead_group_list(struct uct *u, struct board *b, struct move_queue *mq)
 104 {
 105         struct group_judgement gj;
 106         gj.thres = GJ_THRES;
 107         gj.gs = alloca(board_size2(b) * sizeof(gj.gs[0]));
 108         board_ownermap_judge_group(b, &u->ownermap, &gj);
 109         groups_of_status(b, &gj, GS_DEAD, mq);
 110 }
 111
 112 bool
 113 uct_pass_is_safe(struct uct *u, struct board *b, enum stone color, bool pass_all_alive)
 114 {
 115         if (u->ownermap.playouts < GJ_MINGAMES)
 116                 return false;
 117
 118         struct move_queue mq = { .moves = 0 };
 119         if (!pass_all_alive)
 120                 dead_group_list(u, b, &mq);
 121         return pass_is_safe(b, color, &mq);
 122 }
 123
 124
 125 static void
 126 uct_printhook_ownermap(struct board *board, coord_t c, FILE *f)
 127 {
 128         struct uct *u = board->es;
 129         assert(u);
 130         const char chr[] = ":XO,"; // dame, black, white, unclear
 131         const char chm[] = ":xo,";
 132         char ch = chr[board_ownermap_judge_point(&u->ownermap, c, GJ_THRES)];
 133         if (ch == ',') { // less precise estimate then?
 134                 ch = chm[board_ownermap_judge_point(&u->ownermap, c, 0.67)];
 135         }
 136         fprintf(f, "%c ", ch);
 137 }
 138
 139 static char *
 140 uct_notify_play(struct engine *e, struct board *b, struct move *m)
 141 {
 142         struct uct *u = e->data;
 143         if (!u->t) {
 144                 /* No state, create one - this is probably game beginning
 145                  * and we need to load the opening book right now. */
 146                 prepare_move(e, b, m->color);
 147                 assert(u->t);
 148         }
 149
 150         /* Stop pondering. */
 151         /* XXX: If we are about to receive multiple 'play' commands,
 152          * e.g. in a rengo, we will not ponder during the rest of them. */
 153         uct_pondering_stop(u);
 154
 155         if (is_resign(m->coord)) {
 156                 /* Reset state. */
 157                 reset_state(u);
 158                 return NULL;
 159         }
 160
 161         /* Promote node of the appropriate move to the tree root. */
 162         assert(u->t->root);
 163         if (!tree_promote_at(u->t, b, m->coord)) {
 164                 if (UDEBUGL(0))
 165                         fprintf(stderr, "Warning: Cannot promote move node! Several play commands in row?\n");
 166                 reset_state(u);
 167                 return NULL;
 168         }
 169
 170         return NULL;
 171 }
 172
 173 static char *
 174 uct_chat(struct engine *e, struct board *b, char *cmd)
 175 {
 176         struct uct *u = e->data;
 177         static char reply[1024];
 178
 179         cmd += strspn(cmd, " \n\t");
 180         if (!strncasecmp(cmd, "winrate", 7)) {
 181                 if (!u->t)
 182                         return "no game context (yet?)";
 183                 enum stone color = u->t->root_color;
 184                 struct tree_node *n = u->t->root;
 185                 snprintf(reply, 1024, "In %d playouts at %d threads, %s %s can win with %.2f%% probability",
 186                          n->u.playouts, u->threads, stone2str(color), coord2sstr(n->coord, b),
 187                          tree_node_get_value(u->t, -1, n->u.value) * 100);
 188                 if (abs(u->t->extra_komi) >= 0.5) {
 189                         sprintf(reply + strlen(reply), ", while self-imposing extra komi %.1f",
 190                                 u->t->extra_komi);
 191                 }
 192                 strcat(reply, ".");
 193                 return reply;
 194         }
 195         return NULL;
 196 }
 197
 198 static void
 199 uct_dead_group_list(struct engine *e, struct board *b, struct move_queue *mq)
 200 {
 201         struct uct *u = e->data;
 202
 203         /* This means the game is probably over, no use pondering on. */
 204         uct_pondering_stop(u);
 205
 206         if (u->pass_all_alive)
 207                 return; // no dead groups
 208
 209         bool mock_state = false;
 210
 211         if (!u->t) {
 212                 /* No state, but we cannot just back out - we might
 213                  * have passed earlier, only assuming some stones are
 214                  * dead, and then re-connected, only to lose counting
 215                  * when all stones are assumed alive. */
 216                 /* Mock up some state and seed the ownermap by few
 217                  * simulations. */
 218                 prepare_move(e, b, S_BLACK); assert(u->t);
 219                 for (int i = 0; i < GJ_MINGAMES; i++)
 220                         uct_playout(u, b, S_BLACK, u->t);
 221                 mock_state = true;
 222         }
 223
 224         dead_group_list(u, b, mq);
 225
 226         if (mock_state) {
 227                 /* Clean up the mock state in case we will receive
 228                  * a genmove; we could get a non-alternating-move
 229                  * error from prepare_move() in that case otherwise. */
 230                 reset_state(u);
 231         }
 232 }
 233
 234 static void
 235 playout_policy_done(struct playout_policy *p)
 236 {
 237         if (p->done) p->done(p);
 238         if (p->data) free(p->data);
 239         free(p);
 240 }
 241
 242 static void
 243 uct_done(struct engine *e)
 244 {
 245         /* This is called on engine reset, especially when clear_board
 246          * is received and new game should begin. */
 247         struct uct *u = e->data;
 248         uct_pondering_stop(u);
 249         if (u->t) reset_state(u);
 250         free(u->ownermap.map);
 251
 252         free(u->policy);
 253         free(u->random_policy);
 254         playout_policy_done(u->playout);
 255         uct_prior_done(u->prior);
 256 }
 257
 258
 259 /* Pachi threading structure (if uct_playouts_parallel() is used):
 260  *
 261  * main thread
 262  *   |         main(), GTP communication, ...
 263  *   |         starts and stops the search managed by thread_manager
 264  *   |
 265  * thread_manager
 266  *   |         spawns and collects worker threads
 267  *   |
 268  * worker0
 269  * worker1
 270  * ...
 271  * workerK
 272  *             uct_playouts() loop, doing descend-playout until uct_halt
 273  *
 274  * Another way to look at it is by functions (lines denote thread boundaries):
 275  *
 276  * | uct_genmove()
 277  * | uct_search()            (uct_search_start() .. uct_search_stop())
 278  * | -----------------------
 279  * | spawn_thread_manager()
 280  * | -----------------------
 281  * | spawn_worker()
 282  * V uct_playouts() */
 283
 284 /* Set in thread manager in case the workers should stop. */
 285 volatile sig_atomic_t uct_halt = 0;
 286 /* ID of the running worker thread. */
 287 __thread int thread_id = -1;
 288 /* ID of the thread manager. */
 289 static pthread_t thread_manager;
 290 static bool thread_manager_running;
 291
 292 static pthread_mutex_t finish_mutex = PTHREAD_MUTEX_INITIALIZER;
 293 static pthread_cond_t finish_cond = PTHREAD_COND_INITIALIZER;
 294 static volatile int finish_thread;
 295 static pthread_mutex_t finish_serializer = PTHREAD_MUTEX_INITIALIZER;
 296
 297 struct spawn_ctx {
 298         int tid;
 299         struct uct *u;
 300         struct board *b;
 301         enum stone color;
 302         struct tree *t;
 303         unsigned long seed;
 304         int games;
 305 };
 306
 307 static void *
 308 spawn_worker(void *ctx_)
 309 {
 310         struct spawn_ctx *ctx = ctx_;
 311         /* Setup */
 312         fast_srandom(ctx->seed);
 313         thread_id = ctx->tid;
 314         /* Run */
 315         ctx->games = uct_playouts(ctx->u, ctx->b, ctx->color, ctx->t);
 316         /* Finish */
 317         pthread_mutex_lock(&finish_serializer);
 318         pthread_mutex_lock(&finish_mutex);
 319         finish_thread = ctx->tid;
 320         pthread_cond_signal(&finish_cond);
 321         pthread_mutex_unlock(&finish_mutex);
 322         return ctx;
 323 }
 324
 325 /* Thread manager, controlling worker threads. It must be called with
 326  * finish_mutex lock held, but it will unlock it itself before exiting;
 327  * this is necessary to be completely deadlock-free. */
 328 /* The finish_cond can be signalled for it to stop; in that case,
 329  * the caller should set finish_thread = -1. */
 330 /* After it is started, it will update mctx->t to point at some tree
 331  * used for the actual search (matters only for TM_ROOT), on return
 332  * it will set mctx->games to the number of performed simulations. */
 333 static void *
 334 spawn_thread_manager(void *ctx_)
 335 {
 336         /* In thread_manager, we use only some of the ctx fields. */
 337         struct spawn_ctx *mctx = ctx_;
 338         struct uct *u = mctx->u;
 339         struct tree *t = mctx->t;
 340         bool shared_tree = u->parallel_tree;
 341         fast_srandom(mctx->seed);
 342
 343         int played_games = 0;
 344         pthread_t threads[u->threads];
 345         int joined = 0;
 346
 347         uct_halt = 0;
 348
 349         /* Spawn threads... */
 350         for (int ti = 0; ti < u->threads; ti++) {
 351                 struct spawn_ctx *ctx = malloc(sizeof(*ctx));
 352                 ctx->u = u; ctx->b = mctx->b; ctx->color = mctx->color;
 353                 mctx->t = ctx->t = shared_tree ? t : tree_copy(t);
 354                 ctx->tid = ti; ctx->seed = fast_random(65536) + ti;
 355                 pthread_create(&threads[ti], NULL, spawn_worker, ctx);
 356                 if (UDEBUGL(2))
 357                         fprintf(stderr, "Spawned worker %d\n", ti);
 358         }
 359
 360         /* ...and collect them back: */
 361         while (joined < u->threads) {
 362                 /* Wait for some thread to finish... */
 363                 pthread_cond_wait(&finish_cond, &finish_mutex);
 364                 if (finish_thread < 0) {
 365                         /* Stop-by-caller. Tell the workers to wrap up. */
 366                         uct_halt = 1;
 367                         continue;
 368                 }
 369                 /* ...and gather its remnants. */
 370                 struct spawn_ctx *ctx;
 371                 pthread_join(threads[finish_thread], (void **) &ctx);
 372                 played_games += ctx->games;
 373                 joined++;
 374                 if (!shared_tree) {
 375                         if (ctx->t == mctx->t) mctx->t = t;
 376                         tree_merge(t, ctx->t);
 377                         tree_done(ctx->t);
 378                 }
 379                 free(ctx);
 380                 if (UDEBUGL(2))
 381                         fprintf(stderr, "Joined worker %d\n", finish_thread);
 382                 pthread_mutex_unlock(&finish_serializer);
 383         }
 384
 385         pthread_mutex_unlock(&finish_mutex);
 386
 387         if (!shared_tree)
 388                 tree_normalize(mctx->t, u->threads);
 389
 390         mctx->games = played_games;
 391         return mctx;
 392 }
 393
 394 static struct spawn_ctx *
 395 uct_search_start(struct uct *u, struct board *b, enum stone color, struct tree *t)
 396 {
 397         assert(u->threads > 0);
 398         assert(!thread_manager_running);
 399
 400         struct spawn_ctx ctx = { .u = u, .b = b, .color = color, .t = t, .seed = fast_random(65536) };
 401         static struct spawn_ctx mctx; mctx = ctx;
 402         pthread_mutex_lock(&finish_mutex);
 403         pthread_create(&thread_manager, NULL, spawn_thread_manager, &mctx);
 404         thread_manager_running = true;
 405         return &mctx;
 406 }
 407
 408 static struct spawn_ctx *
 409 uct_search_stop(void)
 410 {
 411         assert(thread_manager_running);
 412
 413         /* Signal thread manager to stop the workers. */
 414         pthread_mutex_lock(&finish_mutex);
 415         finish_thread = -1;
 416         pthread_cond_signal(&finish_cond);
 417         pthread_mutex_unlock(&finish_mutex);
 418
 419         /* Collect the thread manager. */
 420         struct spawn_ctx *pctx;
 421         thread_manager_running = false;
 422         pthread_join(thread_manager, (void **) &pctx);
 423         return pctx;
 424 }
 425
 426
 427 /* Pre-process time_info for search control. */
 428 static void
 429 time_prep(struct time_info *ti)
 430 {
 431         if (ti->period == TT_TOTAL) {
 432                 fprintf(stderr, "Warning: TT_TOTAL time mode not supported, resetting to defaults.\n");
 433                 ti->period = TT_NULL;
 434         }
 435         if (ti->period == TT_NULL) {
 436                 ti->period = TT_MOVE;
 437                 ti->dim = TD_GAMES;
 438                 ti->len.games = MC_GAMES;
 439         }
 440 }
 441
 442 /* Run time-limited MCTS search on foreground. */
 443 static int
 444 uct_search(struct uct *u, struct board *b, struct time_info *ti, enum stone color, struct tree *t)
 445 {
 446         time_prep(ti);
 447         if (UDEBUGL(2) && u->t->root->u.playouts > 0)
 448                 fprintf(stderr, "<pre-simulated %d games skipped>\n", u->t->root->u.playouts);
 449
 450         /* Number of last game with progress print. */
 451         int last_print = t->root->u.playouts;
 452         /* Number of simulations to wait before next print. */
 453         int print_interval = TREE_SIMPROGRESS_INTERVAL * (u->thread_model == TM_ROOT ? 1 : u->threads);
 454         /* Printed notification about full memory? */
 455         bool print_fullmem = false;
 456
 457         struct spawn_ctx *ctx = uct_search_start(u, b, color, t);
 458
 459         /* The search tree is ctx->t. This is normally == t, but in case of
 460          * TM_ROOT, it is one of the trees belonging to the independent
 461          * workers. It is important to reference ctx->t directly since the
 462          * thread manager will swap the tree pointer asynchronously. */
 463         /* XXX: This means TM_ROOT support is suboptimal since single stalled
 464          * thread can stall the others in case of limiting the search by game
 465          * count. However, TM_ROOT just does not deserve any more extra code
 466          * right now. */
 467
 468         /* Set up the intervals and deadlines. */
 469         struct timespec busywait_stop;
 470         if (ti->dim == TD_WALLTIME) {
 471                 clock_gettime(CLOCK_REALTIME, &busywait_stop);
 472                 assert(ti->period == TT_MOVE);
 473                 /* TODO: TT_TOTAL - allocate /(5*(board_size(b)-2)) of total time. */
 474                 time_add(&busywait_stop, &ti->len.walltime);
 475                 /* TODO: Safety buffer (2s? but depend on available time if too small). */
 476         }
 477         struct timespec busywait_interval = TREE_BUSYWAIT_INTERVAL;
 478
 479         /* Now, just periodically poll the search tree. */
 480         while (1) {
 481                 nanosleep(&busywait_interval, NULL);
 482                 int i = ctx->t->root->u.playouts;
 483
 484                 /* Print progress? */
 485                 if (i - last_print > print_interval) {
 486                         last_print += print_interval; // keep the numbers tidy
 487                         uct_progress_status(u, ctx->t, color, last_print);
 488                 }
 489                 if (!print_fullmem && ctx->t->nodes_size > u->max_tree_size) {
 490                         if (UDEBUGL(2))
 491                                 fprintf(stderr, "memory limit hit (%ld > %lu)\n", ctx->t->nodes_size, u->max_tree_size);
 492                         print_fullmem = true;
 493                 }
 494
 495                 /* Check against time settings. */
 496                 bool stop = false;
 497                 assert(ti->period == TT_MOVE);
 498                 switch (ti->dim) {
 499                         case TD_WALLTIME:
 500                                 stop = time_passed(&busywait_stop);
 501                                 break;
 502                         case TD_GAMES:
 503                                 stop = i > ti->len.games;
 504                                 break;
 505                 }
 506                 if (stop) break;
 507
 508                 /* Early break in won situation. */
 509                 struct tree_node *best = u->policy->choose(u->policy, ctx->t->root, b, color);
 510                 if (best && ((best->u.playouts >= 2000 && tree_node_get_value(ctx->t, 1, best->u.value) >= u->loss_threshold)
 511                              || (best->u.playouts >= 500 && tree_node_get_value(ctx->t, 1, best->u.value) >= 0.95)))
 512                         break;
 513                 /* TODO: Early break if best->variance goes under threshold. */
 514                 /* TODO: Simulate longer if best of #sims != best of value. */
 515         }
 516
 517         ctx = uct_search_stop();
 518
 519         if (UDEBUGL(2))
 520                 tree_dump(t, u->dumpthres);
 521         if (UDEBUGL(0))
 522                 uct_progress_status(u, t, color, ctx->games);
 523
 524         return ctx->games;
 525 }
 526
 527
 528 /* Start pondering background with @color to play. */
 529 static void
 530 uct_pondering_start(struct uct *u, struct board *b0, struct tree *t, enum stone color)
 531 {
 532         if (UDEBUGL(1))
 533                 fprintf(stderr, "Starting to ponder with color %s\n", stone2str(stone_other(color)));
 534
 535         /* We need a local board copy to ponder upon. */
 536         struct board *b = malloc(sizeof(*b)); board_copy(b, b0);
 537
 538         /* *b0 did not have the genmove'd move played yet. */
 539         struct move m = { t->root->coord, t->root_color };
 540         int res = board_play(b, &m);
 541         assert(res >= 0);
 542
 543         /* Start MCTS manager thread "headless". */
 544         uct_search_start(u, b, color, t);
 545 }
 546
 547 /* uct_search_stop() frontend for the pondering (non-genmove) mode. */
 548 static void
 549 uct_pondering_stop(struct uct *u)
 550 {
 551         if (!thread_manager_running)
 552                 return;
 553
 554         /* Stop the thread manager. */
 555         struct spawn_ctx *ctx = uct_search_stop();
 556         if (UDEBUGL(1)) {
 557                 fprintf(stderr, "(pondering) ");
 558                 uct_progress_status(u, ctx->t, ctx->color, ctx->games);
 559         }
 560         free(ctx->b);
 561 }
 562
 563
 564 static coord_t *
 565 uct_genmove(struct engine *e, struct board *b, struct time_info *ti, enum stone color, bool pass_all_alive)
 566 {
 567         struct uct *u = e->data;
 568
 569         if (b->superko_violation) {
 570                 fprintf(stderr, "!!! WARNING: SUPERKO VIOLATION OCCURED BEFORE THIS MOVE\n");
 571                 fprintf(stderr, "Maybe you play with situational instead of positional superko?\n");
 572                 fprintf(stderr, "I'm going to ignore the violation, but note that I may miss\n");
 573                 fprintf(stderr, "some moves valid under this ruleset because of this.\n");
 574                 b->superko_violation = false;
 575         }
 576
 577         /* Seed the tree. */
 578         uct_pondering_stop(u);
 579         prepare_move(e, b, color);
 580         assert(u->t);
 581
 582         /* Perform the Monte Carlo Tree Search! */
 583         int played_games = uct_search(u, b, ti, color, u->t);
 584
 585         /* Choose the best move from the tree. */
 586         struct tree_node *best = u->policy->choose(u->policy, u->t->root, b, color);
 587         if (!best) {
 588                 reset_state(u);
 589                 return coord_copy(pass);
 590         }
 591         if (UDEBUGL(1))
 592                 fprintf(stderr, "*** WINNER is %s (%d,%d) with score %1.4f (%d/%d:%d games)\n",
 593                         coord2sstr(best->coord, b), coord_x(best->coord, b), coord_y(best->coord, b),
 594                         tree_node_get_value(u->t, 1, best->u.value),
 595                         best->u.playouts, u->t->root->u.playouts, played_games);
 596         if (tree_node_get_value(u->t, 1, best->u.value) < u->resign_ratio && !is_pass(best->coord)) {
 597                 reset_state(u);
 598                 return coord_copy(resign);
 599         }
 600
 601         /* If the opponent just passed and we win counting, always
 602          * pass as well. */
 603         if (b->moves > 1 && is_pass(b->last_move.coord)) {
 604                 /* Make sure enough playouts are simulated. */
 605                 while (u->ownermap.playouts < GJ_MINGAMES)
 606                         uct_playout(u, b, color, u->t);
 607                 if (uct_pass_is_safe(u, b, color, u->pass_all_alive || pass_all_alive)) {
 608                         if (UDEBUGL(0))
 609                                 fprintf(stderr, "<Will rather pass, looks safe enough.>\n");
 610                         best->coord = pass;
 611                 }
 612         }
 613
 614         tree_promote_node(u->t, best);
 615         /* After a pass, pondering is harmful for two reasons:
 616          * (i) We might keep pondering even when the game is over.
 617          * Of course this is the case for opponent resign as well.
 618          * (ii) More importantly, the ownermap will get skewed since
 619          * the UCT will start cutting off any playouts. */
 620         if (u->pondering && !is_pass(best->coord)) {
 621                 uct_pondering_start(u, b, u->t, stone_other(color));
 622         }
 623         return coord_copy(best->coord);
 624 }
 625
 626
 627 bool
 628 uct_genbook(struct engine *e, struct board *b, struct time_info *ti, enum stone color)
 629 {
 630         struct uct *u = e->data;
 631         if (!u->t) prepare_move(e, b, color);
 632         assert(u->t);
 633
 634         if (ti->dim == TD_GAMES) {
 635                 /* Don't count in games that already went into the book. */
 636                 ti->len.games += u->t->root->u.playouts;
 637         }
 638         uct_search(u, b, ti, color, u->t);
 639
 640         assert(ti->dim == TD_GAMES);
 641         tree_save(u->t, b, ti->len.games / 100);
 642
 643         return true;
 644 }
 645
 646 void
 647 uct_dumpbook(struct engine *e, struct board *b, enum stone color)
 648 {
 649         struct tree *t = tree_init(b, color);
 650         tree_load(t, b);
 651         tree_dump(t, 0);
 652         tree_done(t);
 653 }
 654
 655
 656 struct uct *
 657 uct_state_init(char *arg, struct board *b)
 658 {
 659         struct uct *u = calloc(1, sizeof(struct uct));
 660
 661         u->debug_level = 1;
 662         u->gamelen = MC_GAMELEN;
 663         u->mercymin = 0;
 664         u->expand_p = 2;
 665         u->dumpthres = 1000;
 666         u->playout_amaf = true;
 667         u->playout_amaf_nakade = false;
 668         u->amaf_prior = false;
 669         u->max_tree_size = 3072ULL * 1048576;
 670
 671         if (board_size(b) - 2 >= 19)
 672                 u->dynkomi = 200;
 673         u->dynkomi_mask = S_BLACK;
 674
 675         u->threads = 1;
 676         u->thread_model = TM_TREEVL;
 677         u->parallel_tree = true;
 678         u->virtual_loss = true;
 679
 680         u->val_scale = 0.02; u->val_points = 20;
 681
 682         if (arg) {
 683                 char *optspec, *next = arg;
 684                 while (*next) {
 685                         optspec = next;
 686                         next += strcspn(next, ",");
 687                         if (*next) { *next++ = 0; } else { *next = 0; }
 688
 689                         char *optname = optspec;
 690                         char *optval = strchr(optspec, '=');
 691                         if (optval) *optval++ = 0;
 692
 693                         if (!strcasecmp(optname, "debug")) {
 694                                 if (optval)
 695                                         u->debug_level = atoi(optval);
 696                                 else
 697                                         u->debug_level++;
 698                         } else if (!strcasecmp(optname, "mercy") && optval) {
 699                                 /* Minimal difference of black/white captures
 700                                  * to stop playout - "Mercy Rule". Speeds up
 701                                  * hopeless playouts at the expense of some
 702                                  * accuracy. */
 703                                 u->mercymin = atoi(optval);
 704                         } else if (!strcasecmp(optname, "gamelen") && optval) {
 705                                 u->gamelen = atoi(optval);
 706                         } else if (!strcasecmp(optname, "expand_p") && optval) {
 707                                 u->expand_p = atoi(optval);
 708                         } else if (!strcasecmp(optname, "dumpthres") && optval) {
 709                                 u->dumpthres = atoi(optval);
 710                         } else if (!strcasecmp(optname, "playout_amaf")) {
 711                                 /* Whether to include random playout moves in
 712                                  * AMAF as well. (Otherwise, only tree moves
 713                                  * are included in AMAF. Of course makes sense
 714                                  * only in connection with an AMAF policy.) */
 715                                 /* with-without: 55.5% (+-4.1) */
 716                                 if (optval && *optval == '0')
 717                                         u->playout_amaf = false;
 718                                 else
 719                                         u->playout_amaf = true;
 720                         } else if (!strcasecmp(optname, "playout_amaf_nakade")) {
 721                                 /* Whether to include nakade moves from playouts
 722                                  * in the AMAF statistics; this tends to nullify
 723                                  * the playout_amaf effect by adding too much
 724                                  * noise. */
 725                                 if (optval && *optval == '0')
 726                                         u->playout_amaf_nakade = false;
 727                                 else
 728                                         u->playout_amaf_nakade = true;
 729                         } else if (!strcasecmp(optname, "playout_amaf_cutoff") && optval) {
 730                                 /* Keep only first N% of playout stage AMAF
 731                                  * information. */
 732                                 u->playout_amaf_cutoff = atoi(optval);
 733                         } else if ((!strcasecmp(optname, "policy") || !strcasecmp(optname, "random_policy")) && optval) {
 734                                 char *policyarg = strchr(optval, ':');
 735                                 struct uct_policy **p = !strcasecmp(optname, "policy") ? &u->policy : &u->random_policy;
 736                                 if (policyarg)
 737                                         *policyarg++ = 0;
 738                                 if (!strcasecmp(optval, "ucb1")) {
 739                                         *p = policy_ucb1_init(u, policyarg);
 740                                 } else if (!strcasecmp(optval, "ucb1amaf")) {
 741                                         *p = policy_ucb1amaf_init(u, policyarg);
 742                                 } else {
 743                                         fprintf(stderr, "UCT: Invalid tree policy %s\n", optval);
 744                                         exit(1);
 745                                 }
 746                         } else if (!strcasecmp(optname, "playout") && optval) {
 747                                 char *playoutarg = strchr(optval, ':');
 748                                 if (playoutarg)
 749                                         *playoutarg++ = 0;
 750                                 if (!strcasecmp(optval, "moggy")) {
 751                                         u->playout = playout_moggy_init(playoutarg);
 752                                 } else if (!strcasecmp(optval, "light")) {
 753                                         u->playout = playout_light_init(playoutarg);
 754                                 } else if (!strcasecmp(optval, "elo")) {
 755                                         u->playout = playout_elo_init(playoutarg);
 756                                 } else {
 757                                         fprintf(stderr, "UCT: Invalid playout policy %s\n", optval);
 758                                         exit(1);
 759                                 }
 760                         } else if (!strcasecmp(optname, "prior") && optval) {
 761                                 u->prior = uct_prior_init(optval, b);
 762                         } else if (!strcasecmp(optname, "amaf_prior") && optval) {
 763                                 u->amaf_prior = atoi(optval);
 764                         } else if (!strcasecmp(optname, "threads") && optval) {
 765                                 /* By default, Pachi will run with only single
 766                                  * tree search thread! */
 767                                 u->threads = atoi(optval);
 768                         } else if (!strcasecmp(optname, "thread_model") && optval) {
 769                                 if (!strcasecmp(optval, "root")) {
 770                                         /* Root parallelization - each thread
 771                                          * does independent search, trees are
 772                                          * merged at the end. */
 773                                         u->thread_model = TM_ROOT;
 774                                         u->parallel_tree = false;
 775                                         u->virtual_loss = false;
 776                                 } else if (!strcasecmp(optval, "tree")) {
 777                                         /* Tree parallelization - all threads
 778                                          * grind on the same tree. */
 779                                         u->thread_model = TM_TREE;
 780                                         u->parallel_tree = true;
 781                                         u->virtual_loss = false;
 782                                 } else if (!strcasecmp(optval, "treevl")) {
 783                                         /* Tree parallelization, but also
 784                                          * with virtual losses - this discou-
 785                                          * rages most threads choosing the
 786                                          * same tree branches to read. */
 787                                         u->thread_model = TM_TREEVL;
 788                                         u->parallel_tree = true;
 789                                         u->virtual_loss = true;
 790                                 } else {
 791                                         fprintf(stderr, "UCT: Invalid thread model %s\n", optval);
 792                                         exit(1);
 793                                 }
 794                         } else if (!strcasecmp(optname, "pondering")) {
 795                                 /* Keep searching even during opponent's turn. */
 796                                 u->pondering = !optval || atoi(optval);
 797                         } else if (!strcasecmp(optname, "force_seed") && optval) {
 798                                 u->force_seed = atoi(optval);
 799                         } else if (!strcasecmp(optname, "no_book")) {
 800                                 u->no_book = true;
 801                         } else if (!strcasecmp(optname, "dynkomi")) {
 802                                 /* Dynamic komi in handicap game; linearly
 803                                  * decreases to basic settings until move
 804                                  * #optval. */
 805                                 u->dynkomi = optval ? atoi(optval) : 150;
 806                         } else if (!strcasecmp(optname, "dynkomi_mask") && optval) {
 807                                 /* Bitmask of colors the player must be
 808                                  * for dynkomi be applied; you may want
 809                                  * to use dynkomi_mask=3 to allow dynkomi
 810                                  * even in games where Pachi is white. */
 811                                 u->dynkomi_mask = atoi(optval);
 812                         } else if (!strcasecmp(optname, "val_scale") && optval) {
 813                                 /* How much of the game result value should be
 814                                  * influenced by win size. Zero means it isn't. */
 815                                 u->val_scale = atof(optval);
 816                         } else if (!strcasecmp(optname, "val_points") && optval) {
 817                                 /* Maximum size of win to be scaled into game
 818                                  * result value. Zero means boardsize^2. */
 819                                 u->val_points = atoi(optval) * 2; // result values are doubled
 820                         } else if (!strcasecmp(optname, "val_extra")) {
 821                                 /* If false, the score coefficient will be simply
 822                                  * added to the value, instead of scaling the result
 823                                  * coefficient because of it. */
 824                                 u->val_extra = !optval || atoi(optval);
 825                         } else if (!strcasecmp(optname, "root_heuristic") && optval) {
 826                                 /* Whether to bias exploration by root node values
 827                                  * (must be supported by the used policy).
 828                                  * 0: Don't.
 829                                  * 1: Do, value = result.
 830                                  * Try to temper the result:
 831                                  * 2: Do, value = 0.5+(result-expected)/2.
 832                                  * 3: Do, value = 0.5+bzz((result-expected)^2). */
 833                                 u->root_heuristic = atoi(optval);
 834                         } else if (!strcasecmp(optname, "pass_all_alive")) {
 835                                 /* Whether to consider all stones alive at the game
 836                                  * end instead of marking dead groupd. */
 837                                 u->pass_all_alive = !optval || atoi(optval);
 838                         } else if (!strcasecmp(optname, "random_policy_chance") && optval) {
 839                                 /* If specified (N), with probability 1/N, random_policy policy
 840                                  * descend is used instead of main policy descend; useful
 841                                  * if specified policy (e.g. UCB1AMAF) can make unduly biased
 842                                  * choices sometimes, you can fall back to e.g.
 843                                  * random_policy=UCB1. */
 844                                 u->random_policy_chance = atoi(optval);
 845                         } else if (!strcasecmp(optname, "max_tree_size") && optval) {
 846                                 /* Maximum amount of memory [MiB] consumed by the move tree.
 847                                  * Default is 3072 (3 GiB). Note that if you use TM_ROOT,
 848                                  * this limits size of only one of the trees, not all of them
 849                                  * together. */
 850                                 u->max_tree_size = atol(optval) * 1048576;
 851                         } else if (!strcasecmp(optname, "banner") && optval) {
 852                                 /* Additional banner string. This must come as the
 853                                  * last engine parameter. */
 854                                 if (*next) *--next = ',';
 855                                 u->banner = strdup(optval);
 856                                 break;
 857                         } else {
 858                                 fprintf(stderr, "uct: Invalid engine argument %s or missing value\n", optname);
 859                                 exit(1);
 860                         }
 861                 }
 862         }
 863
 864         u->resign_ratio = 0.2; /* Resign when most games are lost. */
 865         u->loss_threshold = 0.85; /* Stop reading if after at least 5000 playouts this is best value. */
 866         if (!u->policy)
 867                 u->policy = policy_ucb1amaf_init(u, NULL);
 868
 869         if (!!u->random_policy_chance ^ !!u->random_policy) {
 870                 fprintf(stderr, "uct: Only one of random_policy and random_policy_chance is set\n");
 871                 exit(1);
 872         }
 873
 874         if (!u->prior)
 875                 u->prior = uct_prior_init(NULL, b);
 876
 877         if (!u->playout)
 878                 u->playout = playout_moggy_init(NULL);
 879         u->playout->debug_level = u->debug_level;
 880
 881         u->ownermap.map = malloc(board_size2(b) * sizeof(u->ownermap.map[0]));
 882
 883         /* Some things remain uninitialized for now - the opening book
 884          * is not loaded and the tree not set up. */
 885         /* This will be initialized in setup_state() at the first move
 886          * received/requested. This is because right now we are not aware
 887          * about any komi or handicap setup and such. */
 888
 889         return u;
 890 }
 891
 892 struct engine *
 893 engine_uct_init(char *arg, struct board *b)
 894 {
 895         struct uct *u = uct_state_init(arg, b);
 896         struct engine *e = calloc(1, sizeof(struct engine));
 897         e->name = "UCT Engine";
 898         e->printhook = uct_printhook_ownermap;
 899         e->notify_play = uct_notify_play;
 900         e->chat = uct_chat;
 901         e->genmove = uct_genmove;
 902         e->dead_group_list = uct_dead_group_list;
 903         e->done = uct_done;
 904         e->data = u;
 905
 906         const char banner[] = "I'm playing UCT. When I'm losing, I will resign, "
 907                 "if I think I win, I play until you pass. "
 908                 "Anyone can send me 'winrate' in private chat to get my assessment of the position.";
 909         if (!u->banner) u->banner = "";
 910         e->comment = malloc(sizeof(banner) + strlen(u->banner) + 1);
 911         sprintf(e->comment, "%s %s", banner, u->banner);
 912
 913         return e;
 914 }