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