uct/walk.c

   1 #include <assert.h>
   2 #include <math.h>
   3 #include <pthread.h>
   4 #include <signal.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8
   9 #define DEBUG
  10
  11 #include "debug.h"
  12 #include "board.h"
  13 #include "move.h"
  14 #include "playout.h"
  15 #include "probdist.h"
  16 #include "random.h"
  17 #include "tactics/util.h"
  18 #include "uct/dynkomi.h"
  19 #include "uct/internal.h"
  20 #include "uct/search.h"
  21 #include "uct/tree.h"
  22 #include "uct/uct.h"
  23 #include "uct/walk.h"
  24 #include "gogui.h"
  25
  26 #define DESCENT_DLEN 512
  27
  28
  29 void
  30 uct_progress_text(struct uct *u, struct tree *t, enum stone color, int playouts)
  31 {
  32         if (!UDEBUGL(0))
  33                 return;
  34
  35         /* Best move */
  36         struct tree_node *best = u->policy->choose(u->policy, t->root, t->board, color, resign);
  37         if (!best) {
  38                 fprintf(stderr, "... No moves left\n");
  39                 return;
  40         }
  41         fprintf(stderr, "[%d] ", playouts);
  42         fprintf(stderr, "best %f ", tree_node_get_value(t, 1, best->u.value));
  43
  44         /* Dynamic komi */
  45         if (t->use_extra_komi)
  46                 fprintf(stderr, "xkomi %.1f ", t->extra_komi);
  47
  48         /* Best sequence */
  49         fprintf(stderr, "| seq ");
  50         for (int depth = 0; depth < 4; depth++) {
  51                 if (best && best->u.playouts >= 25) {
  52                         fprintf(stderr, "%3s ", coord2sstr(node_coord(best), t->board));
  53                         best = u->policy->choose(u->policy, best, t->board, color, resign);
  54                 } else {
  55                         fprintf(stderr, "    ");
  56                 }
  57         }
  58
  59         /* Best candidates */
  60         fprintf(stderr, "| can %c ", color == S_BLACK ? 'b' : 'w');
  61         int cans = 4;
  62         struct tree_node *can[cans];
  63         memset(can, 0, sizeof(can));
  64         best = t->root->children;
  65         while (best) {
  66                 int c = 0;
  67                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
  68                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
  69                 if (c > 0) can[c - 1] = best;
  70                 best = best->sibling;
  71         }
  72         while (--cans >= 0) {
  73                 if (can[cans]) {
  74                         fprintf(stderr, "%3s(%.3f) ",
  75                                 coord2sstr(node_coord(can[cans]), t->board),
  76                                 tree_node_get_value(t, 1, can[cans]->u.value));
  77                 } else {
  78                         fprintf(stderr, "           ");
  79                 }
  80         }
  81
  82         fprintf(stderr, "\n");
  83 }
  84
  85 /* Live gfx: show best sequence in GoGui */
  86 static void
  87 uct_progress_gogui_sequence(struct uct *u, struct tree *t, enum stone color, int playouts)
  88 {
  89         /* Best move */
  90         struct tree_node *best = u->policy->choose(u->policy, t->root, t->board, color, resign);
  91         if (!best) {
  92                 fprintf(stderr, "... No moves left\n");
  93                 return;
  94         }
  95
  96         fprintf(stderr, "gogui-gfx: VAR ");
  97         char *col = "bw";
  98         for (int depth = 0; depth < 4; depth++) {
  99                 if (best && best->u.playouts >= 25) {
 100                         fprintf(stderr, "%c %3s ",
 101                                 col[(depth + (color == S_WHITE)) % 2],
 102                                 coord2sstr(node_coord(best), t->board));
 103                         best = u->policy->choose(u->policy, best, t->board, color, resign);
 104                 }
 105         }
 106         fprintf(stderr, "\n");
 107 }
 108
 109 /* Display best moves graphically in GoGui.
 110  * gfx commands printed on stderr are for live gfx,
 111  * and the last run is kept in a buffer in case we need a gtp reply.
 112  */
 113 static void
 114 uct_progress_gogui_candidates(struct uct *u, struct tree *t, enum stone color, int playouts)
 115 {
 116         struct tree_node *best = t->root->children;
 117         int cans = GOGUI_CANDIDATES;
 118         struct tree_node *can[cans];
 119         memset(can, 0, sizeof(can));
 120         while (best) {
 121                 int c = 0;
 122                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
 123                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
 124                 if (c > 0) can[c - 1] = best;
 125                 best = best->sibling;
 126         }
 127
 128         fprintf(stderr, "gogui-gfx:\n");
 129         char *buf = gogui_gfx_buf;
 130         if (--cans >= 0)
 131                 if (can[cans]) {
 132                         sprintf(buf, "VAR %s %s\n",
 133                                 (color == S_WHITE ? "w" : "b"),
 134                                 coord2sstr(node_coord(can[cans]), t->board) );
 135                         fprintf(stderr, "%s", buf);
 136                         buf += strlen(buf);
 137                 }
 138         while (--cans >= 0)
 139                 if (can[cans]) {
 140                         sprintf(buf, "LABEL %s %i\n",
 141                                 coord2sstr(node_coord(can[cans]), t->board),
 142                                 GOGUI_CANDIDATES - cans);
 143                         fprintf(stderr, "%s", buf);
 144                         buf += strlen(buf);
 145                 }
 146         fprintf(stderr, "\n");
 147 }
 148
 149 /* Display best moves' winrates in GoGui.
 150  * gfx commands printed on stderr are for live gfx,
 151  * and the last run is kept in a buffer in case we need a gtp reply.
 152  */
 153 static void
 154 uct_progress_gogui_winrates(struct uct *u, struct tree *t, enum stone color, int playouts)
 155 {
 156         struct tree_node *best = t->root->children;
 157         int cans = GOGUI_CANDIDATES;
 158         struct tree_node *can[cans];
 159         memset(can, 0, sizeof(can));
 160         while (best) {
 161                 int c = 0;
 162                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
 163                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
 164                 if (c > 0) can[c - 1] = best;
 165                 best = best->sibling;
 166         }
 167
 168         fprintf(stderr, "gogui-gfx:\n");
 169         char *buf = gogui_gfx_buf;
 170         if (--cans >= 0)
 171                 if (can[cans]) {
 172                         sprintf(buf, "VAR %s %s\n",
 173                                 (color == S_WHITE ? "w" : "b"),
 174                                 coord2sstr(node_coord(can[cans]), t->board) );
 175                         fprintf(stderr, "%s", buf);
 176                         buf += strlen(buf);
 177                 }
 178         cans++;
 179
 180         while (--cans >= 0)
 181                 if (can[cans]) {
 182                         sprintf(buf, "LABEL %s .%02u\n",
 183                                 coord2sstr(node_coord(can[cans]), t->board),
 184                                 (unsigned)(tree_node_get_value(t, 1, can[cans]->u.value) * 1000));
 185                         fprintf(stderr, "%s", buf);
 186                         buf += strlen(buf);
 187                 }
 188         fprintf(stderr, "\n");
 189 }
 190
 191 void
 192 uct_progress_json(struct uct *u, struct tree *t, enum stone color, int playouts, coord_t *final, bool big)
 193 {
 194         /* Prefix indicating JSON line. */
 195         fprintf(stderr, "{\"%s\": {", final ? "move" : "frame");
 196
 197         /* Plaout count */
 198         fprintf(stderr, "\"playouts\": %d", playouts);
 199
 200         /* Dynamic komi */
 201         if (t->use_extra_komi)
 202                 fprintf(stderr, ", \"extrakomi\": %.1f", t->extra_komi);
 203
 204         if (final) {
 205                 /* Final move choice */
 206                 fprintf(stderr, ", \"choice\": \"%s\"",
 207                         coord2sstr(*final, t->board));
 208         } else {
 209                 struct tree_node *best = u->policy->choose(u->policy, t->root, t->board, color, resign);
 210                 if (best) {
 211                         /* Best move */
 212                         fprintf(stderr, ", \"best\": {\"%s\": %f}",
 213                                 coord2sstr(best->coord, t->board),
 214                                 tree_node_get_value(t, 1, best->u.value));
 215                 }
 216         }
 217
 218         /* Best candidates */
 219         int cans = 4;
 220         struct tree_node *can[cans];
 221         memset(can, 0, sizeof(can));
 222         struct tree_node *best = t->root->children;
 223         while (best) {
 224                 int c = 0;
 225                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
 226                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
 227                 if (c > 0) can[c - 1] = best;
 228                 best = best->sibling;
 229         }
 230         fprintf(stderr, ", \"can\": [");
 231         while (--cans >= 0) {
 232                 if (!can[cans]) break;
 233                 /* Best sequence */
 234                 fprintf(stderr, "%s[", cans < 3 ? ", " : "");
 235                 best = can[cans];
 236                 for (int depth = 0; depth < 4; depth++) {
 237                         if (!best || best->u.playouts < 25) break;
 238                         fprintf(stderr, "%s{\"%s\":%.3f}", depth > 0 ? "," : "",
 239                                 coord2sstr(best->coord, t->board),
 240                                 tree_node_get_value(t, 1, best->u.value));
 241                         best = u->policy->choose(u->policy, best, t->board, color, resign);
 242                 }
 243                 fprintf(stderr, "]");
 244         }
 245         fprintf(stderr, "]");
 246
 247         if (big) {
 248                 /* Average score. */
 249                 if (t->avg_score.playouts > 0)
 250                         fprintf(stderr, ", \"avg\": {\"score\": %.3f}", t->avg_score.value);
 251                 /* Per-intersection information. */
 252                 fprintf(stderr, ", \"boards\": {");
 253                 /* Position coloring information. */
 254                 fprintf(stderr, "\"colors\": [");
 255                 int f = 0;
 256                 foreach_point(t->board) {
 257                         if (board_at(t->board, c) == S_OFFBOARD) continue;
 258                         fprintf(stderr, "%s%d", f++ > 0 ? "," : "", board_at(t->board, c));
 259                 } foreach_point_end;
 260                 fprintf(stderr, "]");
 261                 /* Ownership statistics. Value (0..1000) for each possible
 262                  * point describes likelihood of this point becoming black.
 263                  * Normally, white rate is 1000-value; exception are possible
 264                  * seki points, but these should be rare. */
 265                 fprintf(stderr, ", \"territory\": [");
 266                 f = 0;
 267                 foreach_point(t->board) {
 268                         if (board_at(t->board, c) == S_OFFBOARD) continue;
 269                         int rate = u->ownermap.map[c][S_BLACK] * 1000 / u->ownermap.playouts;
 270                         fprintf(stderr, "%s%d", f++ > 0 ? "," : "", rate);
 271                 } foreach_point_end;
 272                 fprintf(stderr, "]");
 273                 fprintf(stderr, "}");
 274         }
 275
 276         fprintf(stderr, "}}\n");
 277 }
 278
 279 void
 280 uct_progress_status(struct uct *u, struct tree *t, enum stone color, int playouts, coord_t *final)
 281 {
 282         switch (u->reporting) {
 283                 case UR_TEXT:
 284                         uct_progress_text(u, t, color, playouts);
 285                         break;
 286                 case UR_JSON:
 287                 case UR_JSON_BIG:
 288                         uct_progress_json(u, t, color, playouts, final,
 289                                           u->reporting == UR_JSON_BIG);
 290                         break;
 291                 default: assert(0);
 292         }
 293
 294         if (!gogui_live_gfx)
 295                 return;
 296         switch(gogui_live_gfx) {
 297                 case UR_GOGUI_CAN:
 298                         uct_progress_gogui_candidates(u, t, color, playouts);
 299                         break;
 300                 case UR_GOGUI_SEQ:
 301                         uct_progress_gogui_sequence(u, t, color, playouts);
 302                         break;
 303                 case UR_GOGUI_WR:
 304                         uct_progress_gogui_winrates(u, t, color, playouts);
 305                         break;
 306                 default: assert(0);
 307         }
 308 }
 309
 310 static inline void
 311 record_amaf_move(struct playout_amafmap *amaf, coord_t coord, bool is_ko_capture)
 312 {
 313         assert(amaf->gamelen < MAX_GAMELEN);
 314         amaf->is_ko_capture[amaf->gamelen] = is_ko_capture;
 315         amaf->game[amaf->gamelen++] = coord;
 316 }
 317
 318
 319 struct uct_playout_callback {
 320         struct uct *uct;
 321         struct tree *tree;
 322         struct tree_node *lnode;
 323 };
 324
 325
 326 static coord_t
 327 uct_playout_hook(struct playout_policy *playout, struct playout_setup *setup, struct board *b, enum stone color, int mode)
 328 {
 329         /* XXX: This is used in some non-master branches. */
 330         return pass;
 331 }
 332
 333 static coord_t
 334 uct_playout_prepolicy(struct playout_policy *playout, struct playout_setup *setup, struct board *b, enum stone color)
 335 {
 336         return uct_playout_hook(playout, setup, b, color, 0);
 337 }
 338
 339 static coord_t
 340 uct_playout_postpolicy(struct playout_policy *playout, struct playout_setup *setup, struct board *b, enum stone color)
 341 {
 342         return uct_playout_hook(playout, setup, b, color, 1);
 343 }
 344
 345
 346 static int
 347 uct_leaf_node(struct uct *u, struct board *b, enum stone player_color,
 348               struct playout_amafmap *amaf,
 349               struct uct_descent *descent, int *dlen,
 350               struct tree_node *significant[2],
 351               struct tree *t, struct tree_node *n, enum stone node_color,
 352               char *spaces)
 353 {
 354         enum stone next_color = stone_other(node_color);
 355         int parity = (next_color == player_color ? 1 : -1);
 356
 357         if (UDEBUGL(7))
 358                 fprintf(stderr, "%s*-- UCT playout #%d start [%s] %f\n",
 359                         spaces, n->u.playouts, coord2sstr(node_coord(n), t->board),
 360                         tree_node_get_value(t, -parity, n->u.value));
 361
 362         struct uct_playout_callback upc = {
 363                 .uct = u,
 364                 .tree = t,
 365                 /* TODO: Don't necessarily restart the sequence walk when
 366                  * entering playout. */
 367                 .lnode = NULL,
 368         };
 369
 370         struct playout_setup ps = {
 371                 .gamelen = u->gamelen,
 372                 .mercymin = u->mercymin,
 373                 .prepolicy_hook = uct_playout_prepolicy,
 374                 .postpolicy_hook = uct_playout_postpolicy,
 375                 .hook_data = &upc,
 376         };
 377         int result = play_random_game(&ps, b, next_color,
 378                                       u->playout_amaf ? amaf : NULL,
 379                                       &u->ownermap, u->playout);
 380         if (next_color == S_WHITE) {
 381                 /* We need the result from black's perspective. */
 382                 result = - result;
 383         }
 384         if (UDEBUGL(7))
 385                 fprintf(stderr, "%s -- [%d..%d] %s random playout result %d\n",
 386                         spaces, player_color, next_color, coord2sstr(node_coord(n), t->board), result);
 387
 388         return result;
 389 }
 390
 391 static floating_t
 392 scale_value(struct uct *u, struct board *b, enum stone node_color, struct tree_node *significant[2], int result)
 393 {
 394         floating_t rval = result > 0 ? 1.0 : result < 0 ? 0.0 : 0.5;
 395         if (u->val_scale && result != 0) {
 396                 if (u->val_byavg) {
 397                         if (u->t->avg_score.playouts < 50)
 398                                 return rval;
 399                         result -= u->t->avg_score.value * 2;
 400                 }
 401
 402                 double scale = u->val_scale;
 403                 if (u->val_bytemp) {
 404                         /* xvalue is 0 at 0.5, 1 at 0 or 1 */
 405                         /* No correction for parity necessary. */
 406                         double xvalue = significant[node_color - 1] ? fabs(significant[node_color - 1]->u.value - 0.5) * 2 : 0;
 407                         scale = u->val_bytemp_min + (u->val_scale - u->val_bytemp_min) * xvalue;
 408                 }
 409
 410                 int vp = u->val_points;
 411                 if (!vp) {
 412                         vp = board_size(b) - 1; vp *= vp; vp *= 2;
 413                 }
 414
 415                 floating_t sval = (floating_t) abs(result) / vp;
 416                 sval = sval > 1 ? 1 : sval;
 417                 if (result < 0) sval = 1 - sval;
 418                 if (u->val_extra)
 419                         rval += scale * sval;
 420                 else
 421                         rval = (1 - scale) * rval + scale * sval;
 422                 // fprintf(stderr, "score %d => sval %f, rval %f\n", result, sval, rval);
 423         }
 424         return rval;
 425 }
 426
 427 static double
 428 local_value(struct uct *u, struct board *b, coord_t coord, enum stone color)
 429 {
 430         /* Tactical evaluation of move @coord by color @color, given
 431          * simulation end position @b. I.e., a move is tactically good
 432          * if the resulting group stays on board until the game end. */
 433         /* We can also take into account surrounding stones, e.g. to
 434          * encourage taking off external liberties during a semeai. */
 435         double val = board_local_value(u->local_tree_neival, b, coord, color);
 436         return (color == S_WHITE) ? 1.f - val : val;
 437 }
 438
 439 static void
 440 record_local_sequence(struct uct *u, struct tree *t, struct board *endb,
 441                       struct uct_descent *descent, int dlen, int di,
 442                       enum stone seq_color)
 443 {
 444 #define LTREE_DEBUG if (UDEBUGL(6))
 445
 446         /* Ignore pass sequences. */
 447         if (is_pass(node_coord(descent[di].node)))
 448                 return;
 449
 450         LTREE_DEBUG board_print(endb, stderr);
 451         LTREE_DEBUG fprintf(stderr, "recording local %s sequence: ",
 452                 stone2str(seq_color));
 453
 454         /* Sequences starting deeper are less relevant in general. */
 455         int pval = LTREE_PLAYOUTS_MULTIPLIER;
 456         if (u->local_tree && u->local_tree_depth_decay > 0)
 457                 pval = ((floating_t) pval) / pow(u->local_tree_depth_decay, di - 1);
 458         if (!pval) {
 459                 LTREE_DEBUG fprintf(stderr, "too deep @%d\n", di);
 460                 return;
 461         }
 462
 463         /* Pick the right local tree root... */
 464         struct tree_node *lnode = seq_color == S_BLACK ? t->ltree_black : t->ltree_white;
 465         lnode->u.playouts++;
 466
 467         /* ...determine the sequence value... */
 468         double sval = 0.5;
 469         if (u->local_tree_eval != LTE_EACH) {
 470                 sval = local_value(u, endb, node_coord(descent[di].node), seq_color);
 471                 LTREE_DEBUG fprintf(stderr, "(goal %s[%s %1.3f][%d]) ",
 472                         coord2sstr(node_coord(descent[di].node), t->board),
 473                         stone2str(seq_color), sval, descent[di].node->d);
 474
 475                 if (u->local_tree_eval == LTE_TOTAL) {
 476                         int di0 = di;
 477                         while (di < dlen && (di == di0 || descent[di].node->d < u->tenuki_d)) {
 478                                 enum stone color = (di - di0) % 2 ? stone_other(seq_color) : seq_color;
 479                                 double rval = local_value(u, endb, node_coord(descent[di].node), color);
 480                                 if ((di - di0) % 2)
 481                                         rval = 1 - rval;
 482                                 sval += rval;
 483                                 di++;
 484                         }
 485                         sval /= (di - di0 + 1);
 486                         di = di0;
 487                 }
 488         }
 489
 490         /* ...and record the sequence. */
 491         int di0 = di;
 492         while (di < dlen && !is_pass(node_coord(descent[di].node))
 493                && (di == di0 || descent[di].node->d < u->tenuki_d)) {
 494                 enum stone color = (di - di0) % 2 ? stone_other(seq_color) : seq_color;
 495                 double rval;
 496                 if (u->local_tree_eval != LTE_EACH)
 497                         rval = sval;
 498                 else
 499                         rval = local_value(u, endb, node_coord(descent[di].node), color);
 500                 LTREE_DEBUG fprintf(stderr, "%s[%s %1.3f][%d] ",
 501                         coord2sstr(node_coord(descent[di].node), t->board),
 502                         stone2str(color), rval, descent[di].node->d);
 503                 lnode = tree_get_node(t, lnode, node_coord(descent[di++].node), true);
 504                 assert(lnode);
 505                 stats_add_result(&lnode->u, rval, pval);
 506         }
 507
 508         /* Add lnode for tenuki (pass) if we descended further. */
 509         if (di < dlen) {
 510                 double rval = u->local_tree_eval != LTE_EACH ? sval : 0.5;
 511                 LTREE_DEBUG fprintf(stderr, "pass ");
 512                 lnode = tree_get_node(t, lnode, pass, true);
 513                 assert(lnode);
 514                 stats_add_result(&lnode->u, rval, pval);
 515         }
 516
 517         LTREE_DEBUG fprintf(stderr, "\n");
 518 }
 519
 520
 521 int
 522 uct_playout(struct uct *u, struct board *b, enum stone player_color, struct tree *t)
 523 {
 524         struct board b2;
 525         board_copy(&b2, b);
 526
 527         struct playout_amafmap amaf;
 528         amaf.gamelen = amaf.game_baselen = 0;
 529
 530         /* Walk the tree until we find a leaf, then expand it and do
 531          * a random playout. */
 532         struct tree_node *n = t->root;
 533         enum stone node_color = stone_other(player_color);
 534         assert(node_color == t->root_color);
 535
 536         /* Make sure the root node is expanded. */
 537         if (tree_leaf_node(n) && !__sync_lock_test_and_set(&n->is_expanded, 1))
 538                 tree_expand_node(t, n, &b2, player_color, u, 1);
 539
 540         /* Tree descent history. */
 541         /* XXX: This is somewhat messy since @n and descent[dlen-1].node are
 542          * redundant. */
 543         struct uct_descent descent[DESCENT_DLEN];
 544         descent[0].node = n; descent[0].lnode = NULL;
 545         int dlen = 1;
 546         /* Total value of the sequence. */
 547         struct move_stats seq_value = { .playouts = 0 };
 548         /* The last "significant" node along the descent (i.e. node
 549          * with higher than configured number of playouts). For black
 550          * and white. */
 551         struct tree_node *significant[2] = { NULL, NULL };
 552         if (n->u.playouts >= u->significant_threshold)
 553                 significant[node_color - 1] = n;
 554
 555         int result;
 556         int pass_limit = (board_size(&b2) - 2) * (board_size(&b2) - 2) / 2;
 557         int passes = is_pass(b->last_move.coord) && b->moves > 0;
 558
 559         /* debug */
 560         static char spaces[] = "\0                                                      ";
 561         /* /debug */
 562         if (UDEBUGL(8))
 563                 fprintf(stderr, "--- (#%d) UCT walk with color %d\n", t->root->u.playouts, player_color);
 564
 565         while (!tree_leaf_node(n) && passes < 2) {
 566                 spaces[dlen - 1] = ' '; spaces[dlen] = 0;
 567
 568
 569                 /*** Choose a node to descend to: */
 570
 571                 /* Parity is chosen already according to the child color, since
 572                  * it is applied to children. */
 573                 node_color = stone_other(node_color);
 574                 int parity = (node_color == player_color ? 1 : -1);
 575
 576                 assert(dlen < DESCENT_DLEN);
 577                 descent[dlen] = descent[dlen - 1];
 578                 if (u->local_tree && (!descent[dlen].lnode || descent[dlen].node->d >= u->tenuki_d)) {
 579                         /* Start new local sequence. */
 580                         /* Remember that node_color already holds color of the
 581                          * to-be-found child. */
 582                         descent[dlen].lnode = node_color == S_BLACK ? t->ltree_black : t->ltree_white;
 583                 }
 584
 585                 if (!u->random_policy_chance || fast_random(u->random_policy_chance))
 586                         u->policy->descend(u->policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 587                 else
 588                         u->random_policy->descend(u->random_policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 589
 590
 591                 /*** Perform the descent: */
 592
 593                 if (descent[dlen].node->u.playouts >= u->significant_threshold) {
 594                         significant[node_color - 1] = descent[dlen].node;
 595                 }
 596
 597                 seq_value.playouts += descent[dlen].value.playouts;
 598                 seq_value.value += descent[dlen].value.value * descent[dlen].value.playouts;
 599                 n = descent[dlen++].node;
 600                 assert(n == t->root || n->parent);
 601                 if (UDEBUGL(7))
 602                         fprintf(stderr, "%s+-- UCT sent us to [%s:%d] %d,%f\n",
 603                                 spaces, coord2sstr(node_coord(n), t->board),
 604                                 node_coord(n), n->u.playouts,
 605                                 tree_node_get_value(t, parity, n->u.value));
 606
 607                 if (u->virtual_loss)
 608                         __sync_fetch_and_add(&n->descents, u->virtual_loss);
 609
 610                 struct move m = { node_coord(n), node_color };
 611                 int res = board_play(&b2, &m);
 612
 613                 if (res < 0 || (!is_pass(m.coord) && !group_at(&b2, m.coord)) /* suicide */
 614                     || b2.superko_violation) {
 615                         if (UDEBUGL(4)) {
 616                                 for (struct tree_node *ni = n; ni; ni = ni->parent)
 617                                         fprintf(stderr, "%s<%"PRIhash"> ", coord2sstr(node_coord(ni), t->board), ni->hash);
 618                                 fprintf(stderr, "marking invalid %s node %d,%d res %d group %d spk %d\n",
 619                                         stone2str(node_color), coord_x(node_coord(n),b), coord_y(node_coord(n),b),
 620                                         res, group_at(&b2, m.coord), b2.superko_violation);
 621                         }
 622                         n->hints |= TREE_HINT_INVALID;
 623                         result = 0;
 624                         goto end;
 625                 }
 626
 627                 assert(node_coord(n) >= -1);
 628                 record_amaf_move(&amaf, node_coord(n), board_playing_ko_threat(&b2));
 629
 630                 if (is_pass(node_coord(n)))
 631                         passes++;
 632                 else
 633                         passes = 0;
 634
 635                 enum stone next_color = stone_other(node_color);
 636                 /* We need to make sure only one thread expands the node. If
 637                  * we are unlucky enough for two threads to meet in the same
 638                  * node, the latter one will simply do another simulation from
 639                  * the node itself, no big deal. t->nodes_size may exceed
 640                  * the maximum in multi-threaded case but not by much so it's ok.
 641                  * The size test must be before the test&set not after, to allow
 642                  * expansion of the node later if enough nodes have been freed. */
 643                 if (tree_leaf_node(n)
 644                     && n->u.playouts - u->virtual_loss >= u->expand_p && t->nodes_size < u->max_tree_size
 645                     && !__sync_lock_test_and_set(&n->is_expanded, 1))
 646                         tree_expand_node(t, n, &b2, next_color, u, -parity);
 647         }
 648
 649         amaf.game_baselen = amaf.gamelen;
 650
 651         if (t->use_extra_komi && u->dynkomi->persim) {
 652                 b2.komi += round(u->dynkomi->persim(u->dynkomi, &b2, t, n));
 653         }
 654
 655         /* !!! !!! !!!
 656          * ALERT: The "result" number is extremely confusing. In some parts
 657          * of the code, it is from white's perspective, but here positive
 658          * number is black's win! Be VERY CAREFUL.
 659          * !!! !!! !!! */
 660
 661         // assert(tree_leaf_node(n));
 662         /* In case of parallel tree search, the assertion might
 663          * not hold if two threads chew on the same node. */
 664         result = uct_leaf_node(u, &b2, player_color, &amaf, descent, &dlen, significant, t, n, node_color, spaces);
 665
 666         if (u->policy->wants_amaf && u->playout_amaf_cutoff) {
 667                 unsigned int cutoff = amaf.game_baselen;
 668                 cutoff += (amaf.gamelen - amaf.game_baselen) * u->playout_amaf_cutoff / 100;
 669                 amaf.gamelen = cutoff;
 670         }
 671
 672         /* Record the result. */
 673
 674         assert(n == t->root || n->parent);
 675         floating_t rval = scale_value(u, b, node_color, significant, result);
 676         u->policy->update(u->policy, t, n, node_color, player_color, &amaf, &b2, rval);
 677
 678         stats_add_result(&t->avg_score, result / 2, 1);
 679         if (t->use_extra_komi) {
 680                 stats_add_result(&u->dynkomi->score, result / 2, 1);
 681                 stats_add_result(&u->dynkomi->value, rval, 1);
 682         }
 683
 684         if (u->local_tree && n->parent && !is_pass(node_coord(n)) && dlen > 0) {
 685                 /* Get the local sequences and record them in ltree. */
 686                 /* We will look for sequence starts in our descent
 687                  * history, then run record_local_sequence() for each
 688                  * found sequence start; record_local_sequence() may
 689                  * pick longer sequences from descent history then,
 690                  * which is expected as it will create new lnodes. */
 691                 enum stone seq_color = player_color;
 692                 /* First move always starts a sequence. */
 693                 record_local_sequence(u, t, &b2, descent, dlen, 1, seq_color);
 694                 seq_color = stone_other(seq_color);
 695                 for (int dseqi = 2; dseqi < dlen; dseqi++, seq_color = stone_other(seq_color)) {
 696                         if (u->local_tree_allseq) {
 697                                 /* We are configured to record all subsequences. */
 698                                 record_local_sequence(u, t, &b2, descent, dlen, dseqi, seq_color);
 699                                 continue;
 700                         }
 701                         if (descent[dseqi].node->d >= u->tenuki_d) {
 702                                 /* Tenuki! Record the fresh sequence. */
 703                                 record_local_sequence(u, t, &b2, descent, dlen, dseqi, seq_color);
 704                                 continue;
 705                         }
 706                         if (descent[dseqi].lnode && !descent[dseqi].lnode) {
 707                                 /* Record result for in-descent picked sequence. */
 708                                 record_local_sequence(u, t, &b2, descent, dlen, dseqi, seq_color);
 709                                 continue;
 710                         }
 711                 }
 712         }
 713
 714 end:
 715         /* We need to undo the virtual loss we added during descend. */
 716         if (u->virtual_loss) {
 717                 for (; n->parent; n = n->parent) {
 718                         __sync_fetch_and_sub(&n->descents, u->virtual_loss);
 719                 }
 720         }
 721
 722         board_done_noalloc(&b2);
 723         return result;
 724 }
 725
 726 int
 727 uct_playouts(struct uct *u, struct board *b, enum stone color, struct tree *t, struct time_info *ti)
 728 {
 729         int i;
 730         if (ti && ti->dim == TD_GAMES) {
 731                 for (i = 0; t->root->u.playouts <= ti->len.games && !uct_halt; i++)
 732                         uct_playout(u, b, color, t);
 733         } else {
 734                 for (i = 0; !uct_halt; i++)
 735                         uct_playout(u, b, color, t);
 736         }
 737         return i;
 738 }