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
  25 #define DESCENT_DLEN 512
  26
  27 void
  28 uct_progress_status(struct uct *u, struct tree *t, enum stone color, int playouts)
  29 {
  30         if (!UDEBUGL(0))
  31                 return;
  32
  33         /* Best move */
  34         struct tree_node *best = u->policy->choose(u->policy, t->root, t->board, color, resign);
  35         if (!best) {
  36                 fprintf(stderr, "... No moves left\n");
  37                 return;
  38         }
  39         fprintf(stderr, "[%d] ", playouts);
  40         fprintf(stderr, "best %f ", tree_node_get_value(t, 1, best->u.value));
  41
  42         /* Dynamic komi */
  43         if (t->use_extra_komi)
  44                 fprintf(stderr, "komi %.1f ", t->extra_komi);
  45
  46         /* Best sequence */
  47         fprintf(stderr, "| seq ");
  48         for (int depth = 0; depth < 4; depth++) {
  49                 if (best && best->u.playouts >= 25) {
  50                         fprintf(stderr, "%3s ", coord2sstr(node_coord(best), t->board));
  51                         best = u->policy->choose(u->policy, best, t->board, color, resign);
  52                 } else {
  53                         fprintf(stderr, "    ");
  54                 }
  55         }
  56
  57         /* Best candidates */
  58         fprintf(stderr, "| can ");
  59         int cans = 4;
  60         struct tree_node *can[cans];
  61         memset(can, 0, sizeof(can));
  62         best = t->root->children;
  63         while (best) {
  64                 int c = 0;
  65                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
  66                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
  67                 if (c > 0) can[c - 1] = best;
  68                 best = best->sibling;
  69         }
  70         while (--cans >= 0) {
  71                 if (can[cans]) {
  72                         fprintf(stderr, "%3s(%.3f) ",
  73                                 coord2sstr(node_coord(can[cans]), t->board),
  74                                 tree_node_get_value(t, 1, can[cans]->u.value));
  75                 } else {
  76                         fprintf(stderr, "           ");
  77                 }
  78         }
  79
  80         fprintf(stderr, "\n");
  81 }
  82
  83
  84 static void
  85 record_amaf_move(struct playout_amafmap *amaf, coord_t coord, enum stone color)
  86 {
  87         if (amaf->map[coord] == S_NONE || amaf->map[coord] == color) {
  88                 amaf->map[coord] = color;
  89         } else { // XXX: Respect amaf->record_nakade
  90                 amaf_op(amaf->map[coord], +);
  91         }
  92         amaf->game[amaf->gamelen].coord = coord;
  93         amaf->game[amaf->gamelen].color = color;
  94         amaf->gamelen++;
  95         assert(amaf->gamelen < sizeof(amaf->game) / sizeof(amaf->game[0]));
  96 }
  97
  98
  99 struct uct_playout_callback {
 100         struct uct *uct;
 101         struct tree *tree;
 102         struct tree_node *lnode;
 103 };
 104
 105
 106 static coord_t
 107 uct_playout_hook(struct playout_policy *playout, struct playout_setup *setup, struct board *b, enum stone color, int mode)
 108 {
 109         /* XXX: This is used in some non-master branches. */
 110         return pass;
 111 }
 112
 113 static coord_t
 114 uct_playout_prepolicy(struct playout_policy *playout, struct playout_setup *setup, struct board *b, enum stone color)
 115 {
 116         return uct_playout_hook(playout, setup, b, color, 0);
 117 }
 118
 119 static coord_t
 120 uct_playout_postpolicy(struct playout_policy *playout, struct playout_setup *setup, struct board *b, enum stone color)
 121 {
 122         return uct_playout_hook(playout, setup, b, color, 1);
 123 }
 124
 125
 126 static int
 127 uct_leaf_node(struct uct *u, struct board *b, enum stone player_color,
 128               struct playout_amafmap *amaf,
 129               struct uct_descent *descent, int *dlen,
 130               struct tree_node *significant[2],
 131               struct tree *t, struct tree_node *n, enum stone node_color,
 132               char *spaces)
 133 {
 134         enum stone next_color = stone_other(node_color);
 135         int parity = (next_color == player_color ? 1 : -1);
 136
 137         if (UDEBUGL(7))
 138                 fprintf(stderr, "%s*-- UCT playout #%d start [%s] %f\n",
 139                         spaces, n->u.playouts, coord2sstr(node_coord(n), t->board),
 140                         tree_node_get_value(t, parity, n->u.value));
 141
 142         struct uct_playout_callback upc = {
 143                 .uct = u,
 144                 .tree = t,
 145                 /* TODO: Don't necessarily restart the sequence walk when
 146                  * entering playout. */
 147                 .lnode = NULL,
 148         };
 149
 150         struct playout_setup ps = {
 151                 .gamelen = u->gamelen,
 152                 .mercymin = u->mercymin,
 153                 .prepolicy_hook = uct_playout_prepolicy,
 154                 .postpolicy_hook = uct_playout_postpolicy,
 155                 .hook_data = &upc,
 156         };
 157         int result = play_random_game(&ps, b, next_color,
 158                                       u->playout_amaf ? amaf : NULL,
 159                                       &u->ownermap, u->playout);
 160         if (next_color == S_WHITE) {
 161                 /* We need the result from black's perspective. */
 162                 result = - result;
 163         }
 164         if (UDEBUGL(7))
 165                 fprintf(stderr, "%s -- [%d..%d] %s random playout result %d\n",
 166                         spaces, player_color, next_color, coord2sstr(node_coord(n), t->board), result);
 167
 168         return result;
 169 }
 170
 171 static floating_t
 172 scale_value(struct uct *u, struct board *b, int result)
 173 {
 174         floating_t rval = result > 0 ? 1.0 : result < 0 ? 0.0 : 0.5;
 175         if (u->val_scale && result != 0) {
 176                 int vp = u->val_points;
 177                 if (!vp) {
 178                         vp = board_size(b) - 1; vp *= vp; vp *= 2;
 179                 }
 180
 181                 floating_t sval = (floating_t) abs(result) / vp;
 182                 sval = sval > 1 ? 1 : sval;
 183                 if (result < 0) sval = 1 - sval;
 184                 if (u->val_extra)
 185                         rval += u->val_scale * sval;
 186                 else
 187                         rval = (1 - u->val_scale) * rval + u->val_scale * sval;
 188                 // fprintf(stderr, "score %d => sval %f, rval %f\n", result, sval, rval);
 189         }
 190         return rval;
 191 }
 192
 193 static double
 194 local_value(struct uct *u, struct board *b, coord_t coord, enum stone color)
 195 {
 196         /* Tactical evaluation of move @coord by color @color, given
 197          * simulation end position @b. I.e., a move is tactically good
 198          * if the resulting group stays on board until the game end. */
 199         /* We can also take into account surrounding stones, e.g. to
 200          * encourage taking off external liberties during a semeai. */
 201         double val = board_local_value(u->local_tree_neival, b, coord, color);
 202         return (color == S_WHITE) ? 1.f - val : val;
 203 }
 204
 205 static void
 206 record_local_sequence(struct uct *u, struct tree *t, struct board *endb,
 207                       struct uct_descent *descent, int dlen, int di,
 208                       enum stone seq_color)
 209 {
 210 #define LTREE_DEBUG if (UDEBUGL(6))
 211
 212         /* Ignore pass sequences. */
 213         if (is_pass(node_coord(descent[di].node)))
 214                 return;
 215
 216         LTREE_DEBUG board_print(endb, stderr);
 217         LTREE_DEBUG fprintf(stderr, "recording local %s sequence: ",
 218                 stone2str(seq_color));
 219
 220         /* Sequences starting deeper are less relevant in general. */
 221         int pval = LTREE_PLAYOUTS_MULTIPLIER;
 222         if (u->local_tree && u->local_tree_depth_decay > 0)
 223                 pval = ((floating_t) pval) / pow(u->local_tree_depth_decay, di - 1);
 224         if (!pval) {
 225                 LTREE_DEBUG fprintf(stderr, "too deep @%d\n", di);
 226                 return;
 227         }
 228
 229         /* Pick the right local tree root... */
 230         struct tree_node *lnode = seq_color == S_BLACK ? t->ltree_black : t->ltree_white;
 231         lnode->u.playouts++;
 232
 233         double sval = 0.5;
 234         if (u->local_tree_rootgoal) {
 235                 sval = local_value(u, endb, node_coord(descent[di].node), seq_color);
 236                 LTREE_DEBUG fprintf(stderr, "(goal %s[%s %1.3f][%d]) ",
 237                         coord2sstr(node_coord(descent[di].node), t->board),
 238                         stone2str(seq_color), sval, descent[di].node->d);
 239         }
 240
 241         /* ...and record the sequence. */
 242         int di0 = di;
 243         while (di < dlen && (di == di0 || descent[di].node->d < u->tenuki_d)) {
 244                 enum stone color = (di - di0) % 2 ? stone_other(seq_color) : seq_color;
 245                 double rval;
 246                 if (u->local_tree_rootgoal)
 247                         rval = sval;
 248                 else
 249                         rval = local_value(u, endb, node_coord(descent[di].node), color);
 250                 LTREE_DEBUG fprintf(stderr, "%s[%s %1.3f][%d] ",
 251                         coord2sstr(node_coord(descent[di].node), t->board),
 252                         stone2str(color), rval, descent[di].node->d);
 253                 lnode = tree_get_node(t, lnode, node_coord(descent[di++].node), true);
 254                 assert(lnode);
 255                 stats_add_result(&lnode->u, rval, pval);
 256         }
 257
 258         /* Add lnode for tenuki (pass) if we descended further. */
 259         if (di < dlen) {
 260                 double rval = u->local_tree_rootgoal ? sval : 0.5;
 261                 LTREE_DEBUG fprintf(stderr, "pass ");
 262                 lnode = tree_get_node(t, lnode, pass, true);
 263                 assert(lnode);
 264                 stats_add_result(&lnode->u, rval, pval);
 265         }
 266
 267         LTREE_DEBUG fprintf(stderr, "\n");
 268 }
 269
 270
 271 int
 272 uct_playout(struct uct *u, struct board *b, enum stone player_color, struct tree *t)
 273 {
 274         struct board b2;
 275         board_copy(&b2, b);
 276
 277         struct playout_amafmap *amaf = NULL;
 278         if (u->policy->wants_amaf) {
 279                 amaf = calloc2(1, sizeof(*amaf));
 280                 amaf->map = calloc2(board_size2(&b2) + 1, sizeof(*amaf->map));
 281                 amaf->map++; // -1 is pass
 282         }
 283
 284         /* Walk the tree until we find a leaf, then expand it and do
 285          * a random playout. */
 286         struct tree_node *n = t->root;
 287         enum stone node_color = stone_other(player_color);
 288         assert(node_color == t->root_color);
 289
 290         /* Make sure the root node is expanded. */
 291         if (tree_leaf_node(n) && !__sync_lock_test_and_set(&n->is_expanded, 1))
 292                 tree_expand_node(t, n, &b2, player_color, u, 1);
 293
 294         /* Tree descent history. */
 295         /* XXX: This is somewhat messy since @n and descent[dlen-1].node are
 296          * redundant. */
 297         struct uct_descent descent[DESCENT_DLEN];
 298         descent[0].node = n; descent[0].lnode = NULL;
 299         int dlen = 1;
 300         /* Total value of the sequence. */
 301         struct move_stats seq_value = { .playouts = 0 };
 302         /* The last "significant" node along the descent (i.e. node
 303          * with higher than configured number of playouts). For black
 304          * and white. */
 305         struct tree_node *significant[2] = { NULL, NULL };
 306         if (n->u.playouts >= u->significant_threshold)
 307                 significant[node_color - 1] = n;
 308
 309         int result;
 310         int pass_limit = (board_size(&b2) - 2) * (board_size(&b2) - 2) / 2;
 311         int passes = is_pass(b->last_move.coord) && b->moves > 0;
 312
 313         /* debug */
 314         static char spaces[] = "\0                                                      ";
 315         /* /debug */
 316         if (UDEBUGL(8))
 317                 fprintf(stderr, "--- UCT walk with color %d\n", player_color);
 318
 319         while (!tree_leaf_node(n) && passes < 2) {
 320                 spaces[dlen - 1] = ' '; spaces[dlen] = 0;
 321
 322
 323                 /*** Choose a node to descend to: */
 324
 325                 /* Parity is chosen already according to the child color, since
 326                  * it is applied to children. */
 327                 node_color = stone_other(node_color);
 328                 int parity = (node_color == player_color ? 1 : -1);
 329
 330                 assert(dlen < DESCENT_DLEN);
 331                 descent[dlen] = descent[dlen - 1];
 332                 if (u->local_tree && (!descent[dlen].lnode || descent[dlen].node->d >= u->tenuki_d)) {
 333                         /* Start new local sequence. */
 334                         /* Remember that node_color already holds color of the
 335                          * to-be-found child. */
 336                         descent[dlen].lnode = node_color == S_BLACK ? t->ltree_black : t->ltree_white;
 337                 }
 338
 339                 if (!u->random_policy_chance || fast_random(u->random_policy_chance))
 340                         u->policy->descend(u->policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 341                 else
 342                         u->random_policy->descend(u->random_policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 343
 344
 345                 /*** Perform the descent: */
 346
 347                 if (descent[dlen].node->u.playouts >= u->significant_threshold) {
 348                         significant[node_color - 1] = descent[dlen].node;
 349                 }
 350
 351                 seq_value.playouts += descent[dlen].value.playouts;
 352                 seq_value.value += descent[dlen].value.value * descent[dlen].value.playouts;
 353                 n = descent[dlen++].node;
 354                 assert(n == t->root || n->parent);
 355                 if (UDEBUGL(7))
 356                         fprintf(stderr, "%s+-- UCT sent us to [%s:%d] %d,%f\n",
 357                                 spaces, coord2sstr(node_coord(n), t->board),
 358                                 node_coord(n), n->u.playouts,
 359                                 tree_node_get_value(t, parity, n->u.value));
 360
 361                 /* Add virtual loss if we need to; this is used to discourage
 362                  * other threads from visiting this node in case of multiple
 363                  * threads doing the tree search. */
 364                 if (u->virtual_loss)
 365                         stats_add_result(&n->u, node_color == S_BLACK ? 0.0 : 1.0, u->virtual_loss);
 366
 367                 assert(node_coord(n) >= -1);
 368                 if (amaf && !is_pass(node_coord(n)))
 369                         record_amaf_move(amaf, node_coord(n), node_color);
 370
 371                 struct move m = { node_coord(n), node_color };
 372                 int res = board_play(&b2, &m);
 373
 374                 if (res < 0 || (!is_pass(m.coord) && !group_at(&b2, m.coord)) /* suicide */
 375                     || b2.superko_violation) {
 376                         if (UDEBUGL(4)) {
 377                                 for (struct tree_node *ni = n; ni; ni = ni->parent)
 378                                         fprintf(stderr, "%s<%"PRIhash"> ", coord2sstr(node_coord(ni), t->board), ni->hash);
 379                                 fprintf(stderr, "marking invalid %s node %d,%d res %d group %d spk %d\n",
 380                                         stone2str(node_color), coord_x(node_coord(n),b), coord_y(node_coord(n),b),
 381                                         res, group_at(&b2, m.coord), b2.superko_violation);
 382                         }
 383                         n->hints |= TREE_HINT_INVALID;
 384                         result = 0;
 385                         goto end;
 386                 }
 387
 388                 if (is_pass(node_coord(n)))
 389                         passes++;
 390                 else
 391                         passes = 0;
 392
 393                 enum stone next_color = stone_other(node_color);
 394                 /* We need to make sure only one thread expands the node. If
 395                  * we are unlucky enough for two threads to meet in the same
 396                  * node, the latter one will simply do another simulation from
 397                  * the node itself, no big deal. t->nodes_size may exceed
 398                  * the maximum in multi-threaded case but not by much so it's ok.
 399                  * The size test must be before the test&set not after, to allow
 400                  * expansion of the node later if enough nodes have been freed. */
 401                 if (tree_leaf_node(n)
 402                     && n->u.playouts - u->virtual_loss >= u->expand_p && t->nodes_size < u->max_tree_size
 403                     && !__sync_lock_test_and_set(&n->is_expanded, 1))
 404                         tree_expand_node(t, n, &b2, next_color, u, -parity);
 405         }
 406
 407         if (amaf) {
 408                 amaf->game_baselen = amaf->gamelen;
 409                 amaf->record_nakade = u->playout_amaf_nakade;
 410         }
 411
 412         if (t->use_extra_komi && u->dynkomi->persim) {
 413                 b2.komi += round(u->dynkomi->persim(u->dynkomi, &b2, t, n));
 414         }
 415
 416         if (passes >= 2) {
 417                 /* XXX: No dead groups support. */
 418                 floating_t score = board_official_score(&b2, NULL);
 419                 /* Result from black's perspective (no matter who
 420                  * the player; black's perspective is always
 421                  * what the tree stores. */
 422                 result = - (score * 2);
 423
 424                 if (UDEBUGL(5))
 425                         fprintf(stderr, "[%d..%d] %s p-p scoring playout result %d (W %f)\n",
 426                                 player_color, node_color, coord2sstr(node_coord(n), t->board), result, score);
 427                 if (UDEBUGL(6))
 428                         board_print(&b2, stderr);
 429
 430                 board_ownermap_fill(&u->ownermap, &b2);
 431
 432         } else { // assert(tree_leaf_node(n));
 433                 /* In case of parallel tree search, the assertion might
 434                  * not hold if two threads chew on the same node. */
 435                 result = uct_leaf_node(u, &b2, player_color, amaf, descent, &dlen, significant, t, n, node_color, spaces);
 436         }
 437
 438         if (amaf && u->playout_amaf_cutoff) {
 439                 unsigned int cutoff = amaf->game_baselen;
 440                 cutoff += (amaf->gamelen - amaf->game_baselen) * u->playout_amaf_cutoff / 100;
 441                 /* Now, reconstruct the amaf map. */
 442                 memset(amaf->map, 0, board_size2(&b2) * sizeof(*amaf->map));
 443                 for (unsigned int i = 0; i < cutoff; i++) {
 444                         coord_t coord = amaf->game[i].coord;
 445                         enum stone color = amaf->game[i].color;
 446                         if (amaf->map[coord] == S_NONE || amaf->map[coord] == color) {
 447                                 amaf->map[coord] = color;
 448                         /* Nakade always recorded for in-tree part */
 449                         } else if (amaf->record_nakade || i <= amaf->game_baselen) {
 450                                 amaf_op(amaf->map[node_coord(n)], +);
 451                         }
 452                 }
 453         }
 454
 455         /* Record the result. */
 456
 457         assert(n == t->root || n->parent);
 458         floating_t rval = scale_value(u, b, result);
 459         u->policy->update(u->policy, t, n, node_color, player_color, amaf, &b2, rval);
 460
 461         if (t->use_extra_komi) {
 462                 stats_add_result(&u->dynkomi->score, result / 2, 1);
 463                 stats_add_result(&u->dynkomi->value, rval, 1);
 464         }
 465
 466         if (u->local_tree && n->parent && !is_pass(node_coord(n)) && dlen > 0) {
 467                 /* Get the local sequences and record them in ltree. */
 468                 /* We will look for sequence starts in our descent
 469                  * history, then run record_local_sequence() for each
 470                  * found sequence start; record_local_sequence() may
 471                  * pick longer sequences from descent history then,
 472                  * which is expected as it will create new lnodes. */
 473                 enum stone seq_color = player_color;
 474                 /* First move always starts a sequence. */
 475                 record_local_sequence(u, t, &b2, descent, dlen, 1, seq_color);
 476                 seq_color = stone_other(seq_color);
 477                 for (int dseqi = 2; dseqi < dlen; dseqi++, seq_color = stone_other(seq_color)) {
 478                         if (u->local_tree_allseq) {
 479                                 /* We are configured to record all subsequences. */
 480                                 record_local_sequence(u, t, &b2, descent, dlen, dseqi, seq_color);
 481                                 continue;
 482                         }
 483                         if (descent[dseqi].node->d >= u->tenuki_d) {
 484                                 /* Tenuki! Record the fresh sequence. */
 485                                 record_local_sequence(u, t, &b2, descent, dlen, dseqi, seq_color);
 486                                 continue;
 487                         }
 488                         if (descent[dseqi].lnode && !descent[dseqi].lnode) {
 489                                 /* Record result for in-descent picked sequence. */
 490                                 record_local_sequence(u, t, &b2, descent, dlen, dseqi, seq_color);
 491                                 continue;
 492                         }
 493                 }
 494         }
 495
 496 end:
 497         /* We need to undo the virtual loss we added during descend. */
 498         if (u->virtual_loss) {
 499                 floating_t loss = node_color == S_BLACK ? 0.0 : 1.0;
 500                 for (; n->parent; n = n->parent) {
 501                         stats_rm_result(&n->u, loss, u->virtual_loss);
 502                         loss = 1.0 - loss;
 503                 }
 504         }
 505
 506         if (amaf) {
 507                 free(amaf->map - 1);
 508                 free(amaf);
 509         }
 510         board_done_noalloc(&b2);
 511         return result;
 512 }
 513
 514 int
 515 uct_playouts(struct uct *u, struct board *b, enum stone color, struct tree *t, struct time_info *ti)
 516 {
 517         int i;
 518         if (ti && ti->dim == TD_GAMES) {
 519                 for (i = 0; t->root->u.playouts <= ti->len.games && !uct_halt; i++)
 520                         uct_playout(u, b, color, t);
 521         } else {
 522                 for (i = 0; !uct_halt; i++)
 523                         uct_playout(u, b, color, t);
 524         }
 525         return i;
 526 }