uct/walk.c

   1 #include <assert.h>
   2 #include <pthread.h>
   3 #include <signal.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7
   8 #define DEBUG
   9
  10 #include "debug.h"
  11 #include "board.h"
  12 #include "move.h"
  13 #include "playout.h"
  14 #include "playout/elo.h"
  15 #include "probdist.h"
  16 #include "random.h"
  17 #include "uct/dynkomi.h"
  18 #include "uct/internal.h"
  19 #include "uct/search.h"
  20 #include "uct/tree.h"
  21 #include "uct/uct.h"
  22 #include "uct/walk.h"
  23
  24 void
  25 uct_progress_status(struct uct *u, struct tree *t, enum stone color, int playouts)
  26 {
  27         if (!UDEBUGL(0))
  28                 return;
  29
  30         /* Best move */
  31         struct tree_node *best = u->policy->choose(u->policy, t->root, t->board, color, resign);
  32         if (!best) {
  33                 fprintf(stderr, "... No moves left\n");
  34                 return;
  35         }
  36         fprintf(stderr, "[%d] ", playouts);
  37         fprintf(stderr, "best %f ", tree_node_get_value(t, 1, best->u.value));
  38
  39         /* Max depth */
  40         fprintf(stderr, "deepest % 2d ", t->max_depth - t->root->depth);
  41
  42         /* Best sequence */
  43         fprintf(stderr, "| seq ");
  44         for (int depth = 0; depth < 6; depth++) {
  45                 if (best && best->u.playouts >= 25) {
  46                         fprintf(stderr, "%3s ", coord2sstr(best->coord, t->board));
  47                         best = u->policy->choose(u->policy, best, t->board, color, resign);
  48                 } else {
  49                         fprintf(stderr, "    ");
  50                 }
  51         }
  52
  53         /* Best candidates */
  54         fprintf(stderr, "| can ");
  55         int cans = 4;
  56         struct tree_node *can[cans];
  57         memset(can, 0, sizeof(can));
  58         best = t->root->children;
  59         while (best) {
  60                 int c = 0;
  61                 while ((!can[c] || best->u.playouts > can[c]->u.playouts) && ++c < cans);
  62                 for (int d = 0; d < c; d++) can[d] = can[d + 1];
  63                 if (c > 0) can[c - 1] = best;
  64                 best = best->sibling;
  65         }
  66         while (--cans >= 0) {
  67                 if (can[cans]) {
  68                         fprintf(stderr, "%3s(%.3f) ",
  69                                 coord2sstr(can[cans]->coord, t->board),
  70                                 tree_node_get_value(t, 1, can[cans]->u.value));
  71                 } else {
  72                         fprintf(stderr, "           ");
  73                 }
  74         }
  75
  76         fprintf(stderr, "\n");
  77 }
  78
  79
  80 struct uct_playout_callback {
  81         struct uct *uct;
  82         struct tree *tree;
  83         struct tree_node *lnode;
  84 };
  85
  86 static void
  87 uct_playout_probdist(void *data, struct board *b, enum stone to_play, struct probdist *pd)
  88 {
  89         /* Create probability distribution according to found local tree
  90          * sequence. */
  91         struct uct_playout_callback *upc = data;
  92         assert(upc && upc->tree && pd && b);
  93         coord_t c = b->last_move.coord;
  94         enum stone color = b->last_move.color;
  95
  96         if (is_pass(c)) {
  97                 /* Break local sequence. */
  98                 upc->lnode = NULL;
  99         } else if (upc->lnode) {
 100                 /* Try to follow local sequence. */
 101                 upc->lnode = tree_get_node(upc->tree, upc->lnode, c, false);
 102         }
 103
 104         if (!upc->lnode || !upc->lnode->children) {
 105                 /* There's no local sequence, start new one! */
 106                 upc->lnode = color == S_BLACK ? upc->tree->ltree_black : upc->tree->ltree_white;
 107                 upc->lnode = tree_get_node(upc->tree, upc->lnode, c, false);
 108         }
 109
 110         if (!upc->lnode || !upc->lnode->children) {
 111                 /* We have no local sequence and we cannot find any starting
 112                  * by node corresponding to last move. */
 113                 if (!upc->uct->local_tree_pseqroot) {
 114                         /* Give up then, we have nothing to contribute. */
 115                         return;
 116                 }
 117                 /* Construct probability distribution from possible first
 118                  * sequence move. Remember that @color is color of the
 119                  * *last* move. */
 120                 upc->lnode = color == S_BLACK ? upc->tree->ltree_white : upc->tree->ltree_black;
 121                 if (!upc->lnode->children) {
 122                         /* We don't even have anything in our tree yet. */
 123                         return;
 124                 }
 125         }
 126
 127         /* The probdist has the right structure only if BOARD_GAMMA is defined. */
 128 #ifndef BOARD_GAMMA
 129         assert(0);
 130 #endif
 131
 132         /* Construct probability distribution from lnode children. */
 133         /* XXX: How to derive the appropriate gamma? */
 134         #define li_value(color, li) (li->u.playouts * (color == S_BLACK ? li->u.value : (1 - li->u.value)))
 135         #define li_gamma(color, li) (0.5 + li_value(color, li))
 136         struct tree_node *li = upc->lnode->children;
 137         assert(li);
 138         if (is_pass(li->coord)) {
 139                 /* Tenuki. */
 140                 /* TODO: Spread tenuki gamma over all moves we don't touch. */
 141                 li = li->sibling;
 142         }
 143         for (; li; li = li->sibling) {
 144                 if (board_at(b, li->coord) != S_NONE)
 145                         continue;
 146                 probdist_set(pd, li->coord, pd->items[li->coord] * li_gamma(to_play, li));
 147         }
 148 }
 149
 150
 151 static int
 152 uct_leaf_node(struct uct *u, struct board *b, enum stone player_color,
 153               struct playout_amafmap *amaf,
 154               struct tree *t, struct tree_node *n, enum stone node_color,
 155               char *spaces)
 156 {
 157         enum stone next_color = stone_other(node_color);
 158         int parity = (next_color == player_color ? 1 : -1);
 159
 160         /* If we don't anticipate well the opponent move during pondering
 161          * (the played move has few playouts) we still need more memory
 162          * during genmove to explore the tree actually played.
 163          * For fast_alloc, the tree compaction will free enough memory
 164          * immediately. */
 165         unsigned long max_tree_size = u->max_tree_size;
 166         if (u->pondering && !u->fast_alloc)
 167                 max_tree_size = (max_tree_size * (100 - MIN_FREE_MEM_PERCENT)) / 100;
 168
 169         /* We need to make sure only one thread expands the node. If
 170          * we are unlucky enough for two threads to meet in the same
 171          * node, the latter one will simply do another simulation from
 172          * the node itself, no big deal. t->nodes_size may exceed
 173          * the maximum in multi-threaded case but not by much so it's ok.
 174          * The size test must be before the test&set not after, to allow
 175          * expansion of the node later if enough nodes have been freed. */
 176         if (n->u.playouts >= u->expand_p && t->nodes_size < max_tree_size
 177             && !__sync_lock_test_and_set(&n->is_expanded, 1)) {
 178                 tree_expand_node(t, n, b, next_color, u, parity);
 179         }
 180         if (UDEBUGL(7))
 181                 fprintf(stderr, "%s*-- UCT playout #%d start [%s] %f\n",
 182                         spaces, n->u.playouts, coord2sstr(n->coord, t->board),
 183                         tree_node_get_value(t, parity, n->u.value));
 184
 185         /* TODO: Don't necessarily restart the sequence walk when entering
 186          * playout. */
 187         struct uct_playout_callback upc = { .uct = u, .tree = t, .lnode = NULL };
 188         if (u->local_tree_playout) {
 189                 /* N.B.: We know this is ELO playout. */
 190                 playout_elo_callback(u->playout, uct_playout_probdist, &upc);
 191         }
 192
 193         struct playout_setup ps = { .gamelen = u->gamelen, .mercymin = u->mercymin };
 194         int result = play_random_game(&ps, b, next_color,
 195                                       u->playout_amaf ? amaf : NULL,
 196                                       &u->ownermap, u->playout);
 197         if (next_color == S_WHITE) {
 198                 /* We need the result from black's perspective. */
 199                 result = - result;
 200         }
 201         if (UDEBUGL(7))
 202                 fprintf(stderr, "%s -- [%d..%d] %s random playout result %d\n",
 203                         spaces, player_color, next_color, coord2sstr(n->coord, t->board), result);
 204
 205         return result;
 206 }
 207
 208 static float
 209 scale_value(struct uct *u, struct board *b, int result)
 210 {
 211         float rval = result > 0;
 212         if (u->val_scale) {
 213                 int vp = u->val_points;
 214                 if (!vp) {
 215                         vp = board_size(b) - 1; vp *= vp; vp *= 2;
 216                 }
 217
 218                 float sval = (float) abs(result) / vp;
 219                 sval = sval > 1 ? 1 : sval;
 220                 if (result < 0) sval = 1 - sval;
 221                 if (u->val_extra)
 222                         rval += u->val_scale * sval;
 223                 else
 224                         rval = (1 - u->val_scale) * rval + u->val_scale * sval;
 225                 // fprintf(stderr, "score %d => sval %f, rval %f\n", result, sval, rval);
 226         }
 227         return rval;
 228 }
 229
 230 static void
 231 record_local_sequence(struct uct *u, struct tree *t,
 232                       struct uct_descent *descent, int dlen, int di,
 233                       enum stone seq_color, float rval)
 234 {
 235         /* Ignore pass sequences. */
 236         if (is_pass(descent[di].node->coord))
 237                 return;
 238
 239 #define LTREE_DEBUG if (UDEBUGL(6))
 240         LTREE_DEBUG fprintf(stderr, "recording result %f in local %s sequence: ",
 241                 rval, stone2str(seq_color));
 242         int di0 = di;
 243
 244         /* Pick the right local tree root... */
 245         struct tree_node *lnode = seq_color == S_BLACK ? t->ltree_black : t->ltree_white;
 246         lnode->u.playouts++;
 247
 248         /* ...and record the sequence. */
 249         while (di < dlen && (di == di0 || descent[di].node->d < u->tenuki_d)) {
 250                 LTREE_DEBUG fprintf(stderr, "%s[%d] ",
 251                         coord2sstr(descent[di].node->coord, t->board),
 252                         descent[di].node->d);
 253                 lnode = tree_get_node(t, lnode, descent[di++].node->coord, true);
 254                 assert(lnode);
 255                 stats_add_result(&lnode->u, rval, 1);
 256         }
 257
 258         /* Add lnode for tenuki (pass) if we descended further. */
 259         if (di < dlen) {
 260                 LTREE_DEBUG fprintf(stderr, "pass ");
 261                 lnode = tree_get_node(t, lnode, pass, true);
 262                 assert(lnode);
 263                 stats_add_result(&lnode->u, rval, 1);
 264         }
 265
 266         LTREE_DEBUG fprintf(stderr, "\n");
 267 }
 268
 269
 270 int
 271 uct_playout(struct uct *u, struct board *b, enum stone player_color, struct tree *t)
 272 {
 273         struct board b2;
 274         board_copy(&b2, b);
 275
 276         struct playout_amafmap *amaf = NULL;
 277         if (u->policy->wants_amaf) {
 278                 amaf = calloc2(1, sizeof(*amaf));
 279                 amaf->map = calloc2(board_size2(&b2) + 1, sizeof(*amaf->map));
 280                 amaf->map++; // -1 is pass
 281         }
 282
 283         /* Walk the tree until we find a leaf, then expand it and do
 284          * a random playout. */
 285         struct tree_node *n = t->root;
 286         enum stone node_color = stone_other(player_color);
 287         assert(node_color == t->root_color);
 288
 289         /* Tree descent history. */
 290         /* XXX: This is somewhat messy since @n and descent[dlen-1].node are
 291          * redundant. */
 292         #define DLEN 512
 293         struct uct_descent descent[DLEN];
 294         descent[0].node = n; descent[0].lnode = NULL;
 295         int dlen = 1;
 296         /* Total value of the sequence. */
 297         struct move_stats seq_value = { .playouts = 0 };
 298
 299         int result;
 300         int pass_limit = (board_size(&b2) - 2) * (board_size(&b2) - 2) / 2;
 301         int passes = is_pass(b->last_move.coord) && b->moves > 0;
 302
 303         /* debug */
 304         int depth = 0;
 305         static char spaces[] = "\0                                                      ";
 306         /* /debug */
 307         if (UDEBUGL(8))
 308                 fprintf(stderr, "--- UCT walk with color %d\n", player_color);
 309
 310         while (!tree_leaf_node(n) && passes < 2) {
 311                 spaces[depth++] = ' '; spaces[depth] = 0;
 312
 313
 314                 /*** Choose a node to descend to: */
 315
 316                 /* Parity is chosen already according to the child color, since
 317                  * it is applied to children. */
 318                 node_color = stone_other(node_color);
 319                 int parity = (node_color == player_color ? 1 : -1);
 320
 321                 assert(dlen < DLEN);
 322                 descent[dlen] = descent[dlen - 1];
 323                 if (u->local_tree && (!descent[dlen].lnode || descent[dlen].node->d >= u->tenuki_d)) {
 324                         /* Start new local sequence. */
 325                         /* Remember that node_color already holds color of the
 326                          * to-be-found child. */
 327                         descent[dlen].lnode = node_color == S_BLACK ? t->ltree_black : t->ltree_white;
 328                 }
 329
 330                 if (!u->random_policy_chance || fast_random(u->random_policy_chance))
 331                         u->policy->descend(u->policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 332                 else
 333                         u->random_policy->descend(u->random_policy, t, &descent[dlen], parity, b2.moves > pass_limit);
 334
 335
 336                 /*** Perform the descent: */
 337
 338                 seq_value.playouts += descent[dlen].value.playouts;
 339                 seq_value.value += descent[dlen].value.value * descent[dlen].value.playouts;
 340                 n = descent[dlen++].node;
 341                 assert(n == t->root || n->parent);
 342                 if (UDEBUGL(7))
 343                         fprintf(stderr, "%s+-- UCT sent us to [%s:%d] %f\n",
 344                                 spaces, coord2sstr(n->coord, t->board), n->coord,
 345                                 tree_node_get_value(t, parity, n->u.value));
 346
 347                 /* Add virtual loss if we need to; this is used to discourage
 348                  * other threads from visiting this node in case of multiple
 349                  * threads doing the tree search. */
 350                 if (u->virtual_loss)
 351                         stats_add_result(&n->u, tree_parity(t, parity) > 0 ? 0 : 1, 1);
 352
 353                 assert(n->coord >= -1);
 354                 if (amaf && !is_pass(n->coord)) {
 355                         if (amaf->map[n->coord] == S_NONE || amaf->map[n->coord] == node_color) {
 356                                 amaf->map[n->coord] = node_color;
 357                         } else { // XXX: Respect amaf->record_nakade
 358                                 amaf_op(amaf->map[n->coord], +);
 359                         }
 360                         amaf->game[amaf->gamelen].coord = n->coord;
 361                         amaf->game[amaf->gamelen].color = node_color;
 362                         amaf->gamelen++;
 363                         assert(amaf->gamelen < sizeof(amaf->game) / sizeof(amaf->game[0]));
 364                 }
 365
 366                 struct move m = { n->coord, node_color };
 367                 int res = board_play(&b2, &m);
 368
 369                 if (res < 0 || (!is_pass(m.coord) && !group_at(&b2, m.coord)) /* suicide */
 370                     || b2.superko_violation) {
 371                         if (UDEBUGL(3)) {
 372                                 for (struct tree_node *ni = n; ni; ni = ni->parent)
 373                                         fprintf(stderr, "%s<%"PRIhash"> ", coord2sstr(ni->coord, t->board), ni->hash);
 374                                 fprintf(stderr, "marking invalid %s node %d,%d res %d group %d spk %d\n",
 375                                         stone2str(node_color), coord_x(n->coord,b), coord_y(n->coord,b),
 376                                         res, group_at(&b2, m.coord), b2.superko_violation);
 377                         }
 378                         n->hints |= TREE_HINT_INVALID;
 379                         result = 0;
 380                         goto end;
 381                 }
 382
 383                 if (is_pass(n->coord))
 384                         passes++;
 385                 else
 386                         passes = 0;
 387         }
 388
 389         if (amaf) {
 390                 amaf->game_baselen = amaf->gamelen;
 391                 amaf->record_nakade = u->playout_amaf_nakade;
 392         }
 393
 394         if (t->use_extra_komi && u->dynkomi->persim) {
 395                 b2.komi += round(u->dynkomi->persim(u->dynkomi, &b2, t, n));
 396         }
 397
 398         if (passes >= 2) {
 399                 /* XXX: No dead groups support. */
 400                 float score = board_official_score(&b2, NULL);
 401                 /* Result from black's perspective (no matter who
 402                  * the player; black's perspective is always
 403                  * what the tree stores. */
 404                 result = - (score * 2);
 405
 406                 if (UDEBUGL(5))
 407                         fprintf(stderr, "[%d..%d] %s p-p scoring playout result %d (W %f)\n",
 408                                 player_color, node_color, coord2sstr(n->coord, t->board), result, score);
 409                 if (UDEBUGL(6))
 410                         board_print(&b2, stderr);
 411
 412                 board_ownermap_fill(&u->ownermap, &b2);
 413
 414         } else { assert(u->parallel_tree || tree_leaf_node(n));
 415                 /* In case of parallel tree search, the assertion might
 416                  * not hold if two threads chew on the same node. */
 417                 result = uct_leaf_node(u, &b2, player_color, amaf, t, n, node_color, spaces);
 418         }
 419
 420         if (amaf && u->playout_amaf_cutoff) {
 421                 int cutoff = amaf->game_baselen;
 422                 cutoff += (amaf->gamelen - amaf->game_baselen) * u->playout_amaf_cutoff / 100;
 423                 /* Now, reconstruct the amaf map. */
 424                 memset(amaf->map, 0, board_size2(&b2) * sizeof(*amaf->map));
 425                 for (int i = 0; i < cutoff; i++) {
 426                         coord_t coord = amaf->game[i].coord;
 427                         enum stone color = amaf->game[i].color;
 428                         if (amaf->map[coord] == S_NONE || amaf->map[coord] == color) {
 429                                 amaf->map[coord] = color;
 430                         /* Nakade always recorded for in-tree part */
 431                         } else if (amaf->record_nakade || i <= amaf->game_baselen) {
 432                                 amaf_op(amaf->map[n->coord], +);
 433                         }
 434                 }
 435         }
 436
 437         assert(n == t->root || n->parent);
 438         if (result != 0) {
 439                 float rval = scale_value(u, b, result);
 440                 u->policy->update(u->policy, t, n, node_color, player_color, amaf, rval);
 441
 442                 if (t->use_extra_komi) {
 443                         stats_add_result(&u->dynkomi->score, result / 2, 1);
 444                         stats_add_result(&u->dynkomi->value, rval, 1);
 445                 }
 446
 447                 if (u->local_tree && n->parent && !is_pass(n->coord) && dlen > 0) {
 448                         /* Possibly transform the rval appropriately. */
 449                         float expval = seq_value.value / seq_value.playouts;
 450                         rval = stats_temper_value(rval, expval, u->local_tree);
 451
 452                         /* Get the local sequences and record them in ltree. */
 453                         /* We will look for sequence starts in our descent
 454                          * history, then run record_local_sequence() for each
 455                          * found sequence start; record_local_sequence() may
 456                          * pick longer sequences from descent history then,
 457                          * which is expected as it will create new lnodes. */
 458                         enum stone seq_color = player_color;
 459                         /* First move always starts a sequence. */
 460                         record_local_sequence(u, t, descent, dlen, 1, seq_color, rval);
 461                         seq_color = stone_other(seq_color);
 462                         for (int dseqi = 2; dseqi < dlen; dseqi++, seq_color = stone_other(seq_color)) {
 463                                 if (u->local_tree_allseq) {
 464                                         /* We are configured to record all subsequences. */
 465                                         record_local_sequence(u, t, descent, dlen, dseqi, seq_color, rval);
 466                                         continue;
 467                                 }
 468                                 if (descent[dseqi].node->d >= u->tenuki_d) {
 469                                         /* Tenuki! Record the fresh sequence. */
 470                                         record_local_sequence(u, t, descent, dlen, dseqi, seq_color, rval);
 471                                         continue;
 472                                 }
 473                                 if (descent[dseqi].lnode && !descent[dseqi].lnode) {
 474                                         /* Record result for in-descent picked sequence. */
 475                                         record_local_sequence(u, t, descent, dlen, dseqi, seq_color, rval);
 476                                         continue;
 477                                 }
 478                         }
 479                 }
 480         }
 481
 482 end:
 483         /* We need to undo the virtual loss we added during descend. */
 484         if (u->virtual_loss) {
 485                 int parity = (node_color == player_color ? 1 : -1);
 486                 for (; n->parent; n = n->parent) {
 487                         stats_rm_result(&n->u, tree_parity(t, parity) > 0 ? 0 : 1, 1);
 488                         parity = -parity;
 489                 }
 490         }
 491
 492         if (amaf) {
 493                 free(amaf->map - 1);
 494                 free(amaf);
 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)
 502 {
 503         int i;
 504         for (i = 0; !uct_halt; i++)
 505                 uct_playout(u, b, color, t);
 506         return i;
 507 }