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 "playout/elo.h"
  16 #include "probdist.h"
  17 #include "random.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 void
  26 uct_progress_status(struct uct *u, struct tree *t, enum stone color, int playouts)
  27 {
  28         if (!UDEBUGL(0))
  29                 return;
  30
  31         /* Best move */
  32         struct tree_node *best = u->policy->choose(u->policy, t->root, t->board, color, resign);
  33         if (!best) {
  34                 fprintf(stderr, "... No moves left\n");
  35                 return;
  36         }
  37         fprintf(stderr, "[%d] ", playouts);
  38         fprintf(stderr, "best %f ", tree_node_get_value(t, 1, best->u.value));
  39
  40         /* Dynamic komi */
  41         if (t->use_extra_komi)
  42                 fprintf(stderr, "komi %.1f ", t->extra_komi);
  43
  44         /* Max depth */
  45         fprintf(stderr, "deepest % 2d ", t->max_depth - t->root->depth);
  46
  47         /* Best sequence */
  48         fprintf(stderr, "| seq ");
  49         for (int depth = 0; depth < 6; depth++) {
  50                 if (best && best->u.playouts >= 25) {
  51                         fprintf(stderr, "%3s ", coord2sstr(best->coord, t->board));
  52                         best = u->policy->choose(u->policy, best, t->board, color, resign);
  53                 } else {
  54                         fprintf(stderr, "    ");
  55                 }
  56         }
  57
  58         /* Best candidates */
  59         fprintf(stderr, "| can ");
  60         int cans = 4;
  61         struct tree_node *can[cans];
  62         memset(can, 0, sizeof(can));
  63         best = t->root->children;
  64         while (best) {
  65                 int c = 0;
  66                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
  67                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
  68                 if (c > 0) can[c - 1] = best;
  69                 best = best->sibling;
  70         }
  71         while (--cans >= 0) {
  72                 if (can[cans]) {
  73                         fprintf(stderr, "%3s(%.3f) ",
  74                                 coord2sstr(can[cans]->coord, t->board),
  75                                 tree_node_get_value(t, 1, can[cans]->u.value));
  76                 } else {
  77                         fprintf(stderr, "           ");
  78                 }
  79         }
  80
  81         fprintf(stderr, "\n");
  82 }
  83
  84
  85 struct uct_playout_callback {
  86         struct uct *uct;
  87         struct tree *tree;
  88         struct tree_node *lnode;
  89 };
  90
  91 static void
  92 uct_playout_probdist(void *data, struct board *b, enum stone to_play, struct probdist *pd)
  93 {
  94         /* Create probability distribution according to found local tree
  95          * sequence. */
  96         struct uct_playout_callback *upc = data;
  97         assert(upc && upc->tree && pd && b);
  98         coord_t c = b->last_move.coord;
  99         enum stone color = b->last_move.color;
 100
 101         if (is_pass(c)) {
 102                 /* Break local sequence. */
 103                 upc->lnode = NULL;
 104         } else if (upc->lnode) {
 105                 /* Try to follow local sequence. */
 106                 upc->lnode = tree_get_node(upc->tree, upc->lnode, c, false);
 107         }
 108
 109         if (!upc->lnode || !upc->lnode->children) {
 110                 /* There's no local sequence, start new one! */
 111                 upc->lnode = color == S_BLACK ? upc->tree->ltree_black : upc->tree->ltree_white;
 112                 upc->lnode = tree_get_node(upc->tree, upc->lnode, c, false);
 113         }
 114
 115         if (!upc->lnode || !upc->lnode->children) {
 116                 /* We have no local sequence and we cannot find any starting
 117                  * by node corresponding to last move. */
 118                 if (!upc->uct->local_tree_pseqroot) {
 119                         /* Give up then, we have nothing to contribute. */
 120                         return;
 121                 }
 122                 /* Construct probability distribution from possible first
 123                  * sequence move. Remember that @color is color of the
 124                  * *last* move. */
 125                 upc->lnode = color == S_BLACK ? upc->tree->ltree_white : upc->tree->ltree_black;
 126                 if (!upc->lnode->children) {
 127                         /* We don't even have anything in our tree yet. */
 128                         return;
 129                 }
 130         }
 131
 132         /* The probdist has the right structure only if BOARD_GAMMA is defined. */
 133 #ifndef BOARD_GAMMA
 134         assert(0);
 135 #endif
 136
 137         /* Construct probability distribution from lnode children. */
 138         /* XXX: How to derive the appropriate gamma? */
 139         #define li_value(color, li) (li->u.playouts * (color == S_BLACK ? li->u.value : (1 - li->u.value)))
 140         #define li_gamma(color, li) (0.5 + li_value(color, li))
 141         struct tree_node *li = upc->lnode->children;
 142         assert(li);
 143         if (is_pass(li->coord)) {
 144                 /* Tenuki. */
 145                 /* TODO: Spread tenuki gamma over all moves we don't touch. */
 146                 li = li->sibling;
 147         }
 148         for (; li; li = li->sibling) {
 149                 if (board_at(b, li->coord) != S_NONE)
 150                         continue;
 151                 probdist_set(pd, li->coord, double_to_fixp(pd->items[li->coord] * li_gamma(to_play, li)));
 152         }
 153 }
 154
 155
 156 static int
 157 uct_leaf_node(struct uct *u, struct board *b, enum stone player_color,
 158               struct playout_amafmap *amaf,
 159               struct tree *t, struct tree_node *n, enum stone node_color,
 160               char *spaces)
 161 {
 162         enum stone next_color = stone_other(node_color);
 163         int parity = (next_color == player_color ? 1 : -1);
 164
 165         /* If we don't anticipate well the opponent move during pondering
 166          * (the played move has few playouts) we still need more memory
 167          * during genmove to explore the tree actually played.
 168          * For fast_alloc, the tree compaction will free enough memory
 169          * immediately. */
 170         unsigned long max_tree_size = u->max_tree_size;
 171         if (u->pondering && !u->fast_alloc)
 172                 max_tree_size = (max_tree_size * (100 - MIN_FREE_MEM_PERCENT)) / 100;
 173
 174         /* We need to make sure only one thread expands the node. If
 175          * we are unlucky enough for two threads to meet in the same
 176          * node, the latter one will simply do another simulation from
 177          * the node itself, no big deal. t->nodes_size may exceed
 178          * the maximum in multi-threaded case but not by much so it's ok.
 179          * The size test must be before the test&set not after, to allow
 180          * expansion of the node later if enough nodes have been freed. */
 181         if (n->u.playouts >= u->expand_p && t->nodes_size < max_tree_size
 182             && !__sync_lock_test_and_set(&n->is_expanded, 1)) {
 183                 tree_expand_node(t, n, b, next_color, u, parity);
 184         }
 185         if (UDEBUGL(7))
 186                 fprintf(stderr, "%s*-- UCT playout #%d start [%s] %f\n",
 187                         spaces, n->u.playouts, coord2sstr(n->coord, t->board),
 188                         tree_node_get_value(t, parity, n->u.value));
 189
 190         /* TODO: Don't necessarily restart the sequence walk when entering
 191          * playout. */
 192         struct uct_playout_callback upc = { .uct = u, .tree = t, .lnode = NULL };
 193         if (u->local_tree_playout) {
 194                 /* N.B.: We know this is ELO playout. */
 195                 playout_elo_callback(u->playout, uct_playout_probdist, &upc);
 196         }
 197
 198         struct playout_setup ps = { .gamelen = u->gamelen, .mercymin = u->mercymin };
 199         int result = play_random_game(&ps, b, next_color,
 200                                       u->playout_amaf ? amaf : NULL,
 201                                       &u->ownermap, u->playout);
 202         if (next_color == S_WHITE) {
 203                 /* We need the result from black's perspective. */
 204                 result = - result;
 205         }
 206         if (UDEBUGL(7))
 207                 fprintf(stderr, "%s -- [%d..%d] %s random playout result %d\n",
 208                         spaces, player_color, next_color, coord2sstr(n->coord, t->board), result);
 209
 210         return result;
 211 }
 212
 213 static float
 214 scale_value(struct uct *u, struct board *b, int result)
 215 {
 216         float rval = result > 0;
 217         if (u->val_scale) {
 218                 int vp = u->val_points;
 219                 if (!vp) {
 220                         vp = board_size(b) - 1; vp *= vp; vp *= 2;
 221                 }
 222
 223                 float sval = (float) abs(result) / vp;
 224                 sval = sval > 1 ? 1 : sval;
 225                 if (result < 0) sval = 1 - sval;
 226                 if (u->val_extra)
 227                         rval += u->val_scale * sval;
 228                 else
 229                         rval = (1 - u->val_scale) * rval + u->val_scale * sval;
 230                 // fprintf(stderr, "score %d => sval %f, rval %f\n", result, sval, rval);
 231         }
 232         return rval;
 233 }
 234
 235 static void
 236 record_local_sequence(struct uct *u, struct tree *t,
 237                       struct uct_descent *descent, int dlen, int di,
 238                       enum stone seq_color, float rval)
 239 {
 240         /* Ignore pass sequences. */
 241         if (is_pass(descent[di].node->coord))
 242                 return;
 243
 244 #define LTREE_DEBUG if (UDEBUGL(6))
 245         LTREE_DEBUG fprintf(stderr, "recording result %f in local %s sequence: ",
 246                 rval, stone2str(seq_color));
 247         int di0 = di;
 248
 249         /* Pick the right local tree root... */
 250         struct tree_node *lnode = seq_color == S_BLACK ? t->ltree_black : t->ltree_white;
 251         lnode->u.playouts++;
 252
 253         /* ...and record the sequence. */
 254         while (di < dlen && (di == di0 || descent[di].node->d < u->tenuki_d)) {
 255                 LTREE_DEBUG fprintf(stderr, "%s[%d] ",
 256                         coord2sstr(descent[di].node->coord, t->board),
 257                         descent[di].node->d);
 258                 lnode = tree_get_node(t, lnode, descent[di++].node->coord, true);
 259                 assert(lnode);
 260                 stats_add_result(&lnode->u, rval, 1);
 261         }
 262
 263         /* Add lnode for tenuki (pass) if we descended further. */
 264         if (di < dlen) {
 265                 LTREE_DEBUG fprintf(stderr, "pass ");
 266                 lnode = tree_get_node(t, lnode, pass, true);
 267                 assert(lnode);
 268                 stats_add_result(&lnode->u, rval, 1);
 269         }
 270
 271         LTREE_DEBUG fprintf(stderr, "\n");
 272 }
 273
 274
 275 int
 276 uct_playout(struct uct *u, struct board *b, enum stone player_color, struct tree *t)
 277 {
 278         struct board b2;
 279         board_copy(&b2, b);
 280
 281         struct playout_amafmap *amaf = NULL;
 282         if (u->policy->wants_amaf) {
 283                 amaf = calloc2(1, sizeof(*amaf));
 284                 amaf->map = calloc2(board_size2(&b2) + 1, sizeof(*amaf->map));
 285                 amaf->map++; // -1 is pass
 286         }
 287
 288         /* Walk the tree until we find a leaf, then expand it and do
 289          * a random playout. */
 290         struct tree_node *n = t->root;
 291         enum stone node_color = stone_other(player_color);
 292         assert(node_color == t->root_color);
 293
 294         /* Tree descent history. */
 295         /* XXX: This is somewhat messy since @n and descent[dlen-1].node are
 296          * redundant. */
 297         #define DLEN 512
 298         struct uct_descent descent[DLEN];
 299         descent[0].node = n; descent[0].lnode = NULL;
 300         int dlen = 1;
 301         /* Total value of the sequence. */
 302         struct move_stats seq_value = { .playouts = 0 };
 303
 304         int result;
 305         int pass_limit = (board_size(&b2) - 2) * (board_size(&b2) - 2) / 2;
 306         int passes = is_pass(b->last_move.coord) && b->moves > 0;
 307
 308         /* debug */
 309         int depth = 0;
 310         static char spaces[] = "\0                                                      ";
 311         /* /debug */
 312         if (UDEBUGL(8))
 313                 fprintf(stderr, "--- UCT walk with color %d\n", player_color);
 314
 315         while (!tree_leaf_node(n) && passes < 2) {
 316                 spaces[depth++] = ' '; spaces[depth] = 0;
 317
 318
 319                 /*** Choose a node to descend to: */
 320
 321                 /* Parity is chosen already according to the child color, since
 322                  * it is applied to children. */
 323                 node_color = stone_other(node_color);
 324                 int parity = (node_color == player_color ? 1 : -1);
 325
 326                 assert(dlen < DLEN);
 327                 descent[dlen] = descent[dlen - 1];
 328                 if (u->local_tree && (!descent[dlen].lnode || descent[dlen].node->d >= u->tenuki_d)) {
 329                         /* Start new local sequence. */
 330                         /* Remember that node_color already holds color of the
 331                          * to-be-found child. */
 332                         descent[dlen].lnode = node_color == S_BLACK ? t->ltree_black : t->ltree_white;
 333                 }
 334
 335                 if (!u->random_policy_chance || fast_random(u->random_policy_chance))
 336                         u->policy->descend(u->policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 337                 else
 338                         u->random_policy->descend(u->random_policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 339
 340
 341                 /*** Perform the descent: */
 342
 343                 seq_value.playouts += descent[dlen].value.playouts;
 344                 seq_value.value += descent[dlen].value.value * descent[dlen].value.playouts;
 345                 n = descent[dlen++].node;
 346                 assert(n == t->root || n->parent);
 347                 if (UDEBUGL(7))
 348                         fprintf(stderr, "%s+-- UCT sent us to [%s:%d] %f\n",
 349                                 spaces, coord2sstr(n->coord, t->board), n->coord,
 350                                 tree_node_get_value(t, parity, n->u.value));
 351
 352                 /* Add virtual loss if we need to; this is used to discourage
 353                  * other threads from visiting this node in case of multiple
 354                  * threads doing the tree search. */
 355                 if (u->virtual_loss)
 356                         stats_add_result(&n->u, tree_parity(t, parity) > 0 ? 0 : 1, 1);
 357
 358                 assert(n->coord >= -1);
 359                 if (amaf && !is_pass(n->coord)) {
 360                         if (amaf->map[n->coord] == S_NONE || amaf->map[n->coord] == node_color) {
 361                                 amaf->map[n->coord] = node_color;
 362                         } else { // XXX: Respect amaf->record_nakade
 363                                 amaf_op(amaf->map[n->coord], +);
 364                         }
 365                         amaf->game[amaf->gamelen].coord = n->coord;
 366                         amaf->game[amaf->gamelen].color = node_color;
 367                         amaf->gamelen++;
 368                         assert(amaf->gamelen < sizeof(amaf->game) / sizeof(amaf->game[0]));
 369                 }
 370
 371                 struct move m = { n->coord, 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(ni->coord, 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(n->coord,b), coord_y(n->coord,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(n->coord))
 389                         passes++;
 390                 else
 391                         passes = 0;
 392         }
 393
 394         if (amaf) {
 395                 amaf->game_baselen = amaf->gamelen;
 396                 amaf->record_nakade = u->playout_amaf_nakade;
 397         }
 398
 399         if (t->use_extra_komi && u->dynkomi->persim) {
 400                 b2.komi += round(u->dynkomi->persim(u->dynkomi, &b2, t, n));
 401         }
 402
 403         if (passes >= 2) {
 404                 /* XXX: No dead groups support. */
 405                 float score = board_official_score(&b2, NULL);
 406                 /* Result from black's perspective (no matter who
 407                  * the player; black's perspective is always
 408                  * what the tree stores. */
 409                 result = - (score * 2);
 410
 411                 if (UDEBUGL(5))
 412                         fprintf(stderr, "[%d..%d] %s p-p scoring playout result %d (W %f)\n",
 413                                 player_color, node_color, coord2sstr(n->coord, t->board), result, score);
 414                 if (UDEBUGL(6))
 415                         board_print(&b2, stderr);
 416
 417                 board_ownermap_fill(&u->ownermap, &b2);
 418
 419         } else { // assert(tree_leaf_node(n));
 420                 /* In case of parallel tree search, the assertion might
 421                  * not hold if two threads chew on the same node. */
 422                 result = uct_leaf_node(u, &b2, player_color, amaf, t, n, node_color, spaces);
 423         }
 424
 425         if (amaf && u->playout_amaf_cutoff) {
 426                 unsigned int cutoff = amaf->game_baselen;
 427                 cutoff += (amaf->gamelen - amaf->game_baselen) * u->playout_amaf_cutoff / 100;
 428                 /* Now, reconstruct the amaf map. */
 429                 memset(amaf->map, 0, board_size2(&b2) * sizeof(*amaf->map));
 430                 for (unsigned int i = 0; i < cutoff; i++) {
 431                         coord_t coord = amaf->game[i].coord;
 432                         enum stone color = amaf->game[i].color;
 433                         if (amaf->map[coord] == S_NONE || amaf->map[coord] == color) {
 434                                 amaf->map[coord] = color;
 435                         /* Nakade always recorded for in-tree part */
 436                         } else if (amaf->record_nakade || i <= amaf->game_baselen) {
 437                                 amaf_op(amaf->map[n->coord], +);
 438                         }
 439                 }
 440         }
 441
 442         assert(n == t->root || n->parent);
 443         if (result != 0) {
 444                 float rval = scale_value(u, b, result);
 445                 u->policy->update(u->policy, t, n, node_color, player_color, amaf, rval);
 446
 447                 if (t->use_extra_komi) {
 448                         stats_add_result(&u->dynkomi->score, result / 2, 1);
 449                         stats_add_result(&u->dynkomi->value, rval, 1);
 450                 }
 451
 452                 if (u->local_tree && n->parent && !is_pass(n->coord) && dlen > 0) {
 453                         /* Possibly transform the rval appropriately. */
 454                         float expval = seq_value.value / seq_value.playouts;
 455                         rval = stats_temper_value(rval, expval, u->local_tree);
 456
 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, descent, dlen, 1, seq_color, rval);
 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, descent, dlen, dseqi, seq_color, rval);
 471                                         continue;
 472                                 }
 473                                 if (descent[dseqi].node->d >= u->tenuki_d) {
 474                                         /* Tenuki! Record the fresh sequence. */
 475                                         record_local_sequence(u, t, descent, dlen, dseqi, seq_color, rval);
 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, descent, dlen, dseqi, seq_color, rval);
 481                                         continue;
 482                                 }
 483                         }
 484                 }
 485         }
 486
 487 end:
 488         /* We need to undo the virtual loss we added during descend. */
 489         if (u->virtual_loss) {
 490                 int parity = (node_color == player_color ? 1 : -1);
 491                 for (; n->parent; n = n->parent) {
 492                         stats_rm_result(&n->u, tree_parity(t, parity) > 0 ? 0 : 1, 1);
 493                         parity = -parity;
 494                 }
 495         }
 496
 497         if (amaf) {
 498                 free(amaf->map - 1);
 499                 free(amaf);
 500         }
 501         board_done_noalloc(&b2);
 502         return result;
 503 }
 504
 505 int
 506 uct_playouts(struct uct *u, struct board *b, enum stone color, struct tree *t)
 507 {
 508         int i;
 509         for (i = 0; !uct_halt; i++)
 510                 uct_playout(u, b, color, t);
 511         return i;
 512 }