18 #include "playout/elo.h"
19 #include "playout/moggy.h"
20 #include "playout/light.h"
24 #include "uct/dynkomi.h"
25 #include "uct/internal.h"
26 #include "uct/prior.h"
31 struct uct_policy
*policy_ucb1_init(struct uct
*u
, char *arg
);
32 struct uct_policy
*policy_ucb1amaf_init(struct uct
*u
, char *arg
);
33 static void uct_pondering_stop(struct uct
*u
);
36 /* Default number of simulations to perform per move.
37 * Note that this is now in total over all threads! (Unless TM_ROOT.) */
38 #define MC_GAMES 80000
39 #define MC_GAMELEN MAX_GAMELEN
40 static const struct time_info default_ti
= {
43 .len
= { .games
= MC_GAMES
},
46 /* How big proportion of ownermap counts must be of one color to consider
49 /* How many games to consider at minimum before judging groups. */
50 #define GJ_MINGAMES 500
52 /* How often to inspect the tree from the main thread to check for playout
53 * stop, progress reports, etc. (in seconds) */
54 #define TREE_BUSYWAIT_INTERVAL 0.1 /* 100ms */
56 /* Once per how many simulations (per thread) to show a progress report line. */
57 #define TREE_SIMPROGRESS_INTERVAL 10000
59 /* When terminating uct_search() early, the safety margin to add to the
60 * remaining playout number estimate when deciding whether the result can
62 #define PLAYOUT_DELTA_SAFEMARGIN 1000
66 setup_state(struct uct
*u
, struct board
*b
, enum stone color
)
68 u
->t
= tree_init(b
, color
, u
->fast_alloc
? u
->max_tree_size
: 0, u
->local_tree_aging
);
70 fast_srandom(u
->force_seed
);
72 fprintf(stderr
, "Fresh board with random seed %lu\n", fast_getseed());
73 //board_print(b, stderr);
74 if (!u
->no_book
&& b
->moves
== 0) {
75 assert(color
== S_BLACK
);
81 reset_state(struct uct
*u
)
84 tree_done(u
->t
); u
->t
= NULL
;
88 setup_dynkomi(struct uct
*u
, struct board
*b
, enum stone to_play
)
90 if (u
->t
->use_extra_komi
&& u
->dynkomi
->permove
)
91 u
->t
->extra_komi
= u
->dynkomi
->permove(u
->dynkomi
, b
, u
->t
);
95 prepare_move(struct engine
*e
, struct board
*b
, enum stone color
)
97 struct uct
*u
= e
->data
;
100 /* Verify that we have sane state. */
102 assert(u
->t
&& b
->moves
);
103 if (color
!= stone_other(u
->t
->root_color
)) {
104 fprintf(stderr
, "Fatal: Non-alternating play detected %d %d\n",
105 color
, u
->t
->root_color
);
110 /* We need fresh state. */
112 setup_state(u
, b
, color
);
115 u
->ownermap
.playouts
= 0;
116 memset(u
->ownermap
.map
, 0, board_size2(b
) * sizeof(u
->ownermap
.map
[0]));
120 dead_group_list(struct uct
*u
, struct board
*b
, struct move_queue
*mq
)
122 struct group_judgement gj
;
124 gj
.gs
= alloca(board_size2(b
) * sizeof(gj
.gs
[0]));
125 board_ownermap_judge_group(b
, &u
->ownermap
, &gj
);
126 groups_of_status(b
, &gj
, GS_DEAD
, mq
);
130 uct_pass_is_safe(struct uct
*u
, struct board
*b
, enum stone color
, bool pass_all_alive
)
132 if (u
->ownermap
.playouts
< GJ_MINGAMES
)
135 struct move_queue mq
= { .moves
= 0 };
137 dead_group_list(u
, b
, &mq
);
138 return pass_is_safe(b
, color
, &mq
);
143 uct_printhook_ownermap(struct board
*board
, coord_t c
, FILE *f
)
145 struct uct
*u
= board
->es
;
147 const char chr
[] = ":XO,"; // dame, black, white, unclear
148 const char chm
[] = ":xo,";
149 char ch
= chr
[board_ownermap_judge_point(&u
->ownermap
, c
, GJ_THRES
)];
150 if (ch
== ',') { // less precise estimate then?
151 ch
= chm
[board_ownermap_judge_point(&u
->ownermap
, c
, 0.67)];
153 fprintf(f
, "%c ", ch
);
157 uct_notify_play(struct engine
*e
, struct board
*b
, struct move
*m
)
159 struct uct
*u
= e
->data
;
161 /* No state, create one - this is probably game beginning
162 * and we need to load the opening book right now. */
163 prepare_move(e
, b
, m
->color
);
167 /* Stop pondering. */
168 /* XXX: If we are about to receive multiple 'play' commands,
169 * e.g. in a rengo, we will not ponder during the rest of them. */
170 uct_pondering_stop(u
);
172 if (is_resign(m
->coord
)) {
178 /* Promote node of the appropriate move to the tree root. */
180 if (!tree_promote_at(u
->t
, b
, m
->coord
)) {
182 fprintf(stderr
, "Warning: Cannot promote move node! Several play commands in row?\n");
190 uct_chat(struct engine
*e
, struct board
*b
, char *cmd
)
192 struct uct
*u
= e
->data
;
193 static char reply
[1024];
195 cmd
+= strspn(cmd
, " \n\t");
196 if (!strncasecmp(cmd
, "winrate", 7)) {
198 return "no game context (yet?)";
199 enum stone color
= u
->t
->root_color
;
200 struct tree_node
*n
= u
->t
->root
;
201 snprintf(reply
, 1024, "In %d playouts at %d threads, %s %s can win with %.2f%% probability",
202 n
->u
.playouts
, u
->threads
, stone2str(color
), coord2sstr(n
->coord
, b
),
203 tree_node_get_value(u
->t
, -1, n
->u
.value
) * 100);
204 if (u
->t
->use_extra_komi
&& abs(u
->t
->extra_komi
) >= 0.5) {
205 sprintf(reply
+ strlen(reply
), ", while self-imposing extra komi %.1f",
215 uct_dead_group_list(struct engine
*e
, struct board
*b
, struct move_queue
*mq
)
217 struct uct
*u
= e
->data
;
219 /* This means the game is probably over, no use pondering on. */
220 uct_pondering_stop(u
);
222 if (u
->pass_all_alive
)
223 return; // no dead groups
225 bool mock_state
= false;
228 /* No state, but we cannot just back out - we might
229 * have passed earlier, only assuming some stones are
230 * dead, and then re-connected, only to lose counting
231 * when all stones are assumed alive. */
232 /* Mock up some state and seed the ownermap by few
234 prepare_move(e
, b
, S_BLACK
); assert(u
->t
);
235 for (int i
= 0; i
< GJ_MINGAMES
; i
++)
236 uct_playout(u
, b
, S_BLACK
, u
->t
);
240 dead_group_list(u
, b
, mq
);
243 /* Clean up the mock state in case we will receive
244 * a genmove; we could get a non-alternating-move
245 * error from prepare_move() in that case otherwise. */
251 playout_policy_done(struct playout_policy
*p
)
253 if (p
->done
) p
->done(p
);
254 if (p
->data
) free(p
->data
);
259 uct_done(struct engine
*e
)
261 /* This is called on engine reset, especially when clear_board
262 * is received and new game should begin. */
263 struct uct
*u
= e
->data
;
264 uct_pondering_stop(u
);
265 if (u
->t
) reset_state(u
);
266 free(u
->ownermap
.map
);
269 free(u
->random_policy
);
270 playout_policy_done(u
->playout
);
271 uct_prior_done(u
->prior
);
275 /* Pachi threading structure (if uct_playouts_parallel() is used):
278 * | main(), GTP communication, ...
279 * | starts and stops the search managed by thread_manager
282 * | spawns and collects worker threads
288 * uct_playouts() loop, doing descend-playout until uct_halt
290 * Another way to look at it is by functions (lines denote thread boundaries):
293 * | uct_search() (uct_search_start() .. uct_search_stop())
294 * | -----------------------
295 * | spawn_thread_manager()
296 * | -----------------------
298 * V uct_playouts() */
300 /* Set in thread manager in case the workers should stop. */
301 volatile sig_atomic_t uct_halt
= 0;
302 /* ID of the running worker thread. */
303 __thread
int thread_id
= -1;
304 /* ID of the thread manager. */
305 static pthread_t thread_manager
;
306 static bool thread_manager_running
;
308 static pthread_mutex_t finish_mutex
= PTHREAD_MUTEX_INITIALIZER
;
309 static pthread_cond_t finish_cond
= PTHREAD_COND_INITIALIZER
;
310 static volatile int finish_thread
;
311 static pthread_mutex_t finish_serializer
= PTHREAD_MUTEX_INITIALIZER
;
324 spawn_worker(void *ctx_
)
326 struct spawn_ctx
*ctx
= ctx_
;
328 fast_srandom(ctx
->seed
);
329 thread_id
= ctx
->tid
;
331 ctx
->games
= uct_playouts(ctx
->u
, ctx
->b
, ctx
->color
, ctx
->t
);
333 pthread_mutex_lock(&finish_serializer
);
334 pthread_mutex_lock(&finish_mutex
);
335 finish_thread
= ctx
->tid
;
336 pthread_cond_signal(&finish_cond
);
337 pthread_mutex_unlock(&finish_mutex
);
341 /* Thread manager, controlling worker threads. It must be called with
342 * finish_mutex lock held, but it will unlock it itself before exiting;
343 * this is necessary to be completely deadlock-free. */
344 /* The finish_cond can be signalled for it to stop; in that case,
345 * the caller should set finish_thread = -1. */
346 /* After it is started, it will update mctx->t to point at some tree
347 * used for the actual search (matters only for TM_ROOT), on return
348 * it will set mctx->games to the number of performed simulations. */
350 spawn_thread_manager(void *ctx_
)
352 /* In thread_manager, we use only some of the ctx fields. */
353 struct spawn_ctx
*mctx
= ctx_
;
354 struct uct
*u
= mctx
->u
;
355 struct tree
*t
= mctx
->t
;
356 bool shared_tree
= u
->parallel_tree
;
357 fast_srandom(mctx
->seed
);
359 int played_games
= 0;
360 pthread_t threads
[u
->threads
];
365 /* Garbage collect the tree by preference when pondering. */
366 if (u
->pondering
&& t
->nodes
&& t
->nodes_size
> t
->max_tree_size
/2) {
367 unsigned long temp_size
= (MIN_FREE_MEM_PERCENT
* t
->max_tree_size
) / 100;
368 t
->root
= tree_garbage_collect(t
, temp_size
, t
->root
);
371 /* Spawn threads... */
372 for (int ti
= 0; ti
< u
->threads
; ti
++) {
373 struct spawn_ctx
*ctx
= malloc(sizeof(*ctx
));
374 ctx
->u
= u
; ctx
->b
= mctx
->b
; ctx
->color
= mctx
->color
;
375 mctx
->t
= ctx
->t
= shared_tree
? t
: tree_copy(t
);
376 ctx
->tid
= ti
; ctx
->seed
= fast_random(65536) + ti
;
377 pthread_create(&threads
[ti
], NULL
, spawn_worker
, ctx
);
379 fprintf(stderr
, "Spawned worker %d\n", ti
);
382 /* ...and collect them back: */
383 while (joined
< u
->threads
) {
384 /* Wait for some thread to finish... */
385 pthread_cond_wait(&finish_cond
, &finish_mutex
);
386 if (finish_thread
< 0) {
387 /* Stop-by-caller. Tell the workers to wrap up. */
391 /* ...and gather its remnants. */
392 struct spawn_ctx
*ctx
;
393 pthread_join(threads
[finish_thread
], (void **) &ctx
);
394 played_games
+= ctx
->games
;
397 if (ctx
->t
== mctx
->t
) mctx
->t
= t
;
398 tree_merge(t
, ctx
->t
);
403 fprintf(stderr
, "Joined worker %d\n", finish_thread
);
404 pthread_mutex_unlock(&finish_serializer
);
407 pthread_mutex_unlock(&finish_mutex
);
410 tree_normalize(mctx
->t
, u
->threads
);
412 mctx
->games
= played_games
;
416 static struct spawn_ctx
*
417 uct_search_start(struct uct
*u
, struct board
*b
, enum stone color
, struct tree
*t
)
419 assert(u
->threads
> 0);
420 assert(!thread_manager_running
);
422 struct spawn_ctx ctx
= { .u
= u
, .b
= b
, .color
= color
, .t
= t
, .seed
= fast_random(65536) };
423 static struct spawn_ctx mctx
; mctx
= ctx
;
424 pthread_mutex_lock(&finish_mutex
);
425 pthread_create(&thread_manager
, NULL
, spawn_thread_manager
, &mctx
);
426 thread_manager_running
= true;
430 static struct spawn_ctx
*
431 uct_search_stop(void)
433 assert(thread_manager_running
);
435 /* Signal thread manager to stop the workers. */
436 pthread_mutex_lock(&finish_mutex
);
438 pthread_cond_signal(&finish_cond
);
439 pthread_mutex_unlock(&finish_mutex
);
441 /* Collect the thread manager. */
442 struct spawn_ctx
*pctx
;
443 thread_manager_running
= false;
444 pthread_join(thread_manager
, (void **) &pctx
);
449 /* Determine whether we should terminate the search early. */
451 uct_search_stop_early(struct uct
*u
, struct tree
*t
, struct board
*b
,
452 struct time_info
*ti
, struct time_stop
*stop
,
453 struct tree_node
*best
, struct tree_node
*best2
,
454 int base_playouts
, int i
)
456 /* Always use at least half the desired time. It is silly
457 * to lose a won game because we played a bad move in 0.1s. */
459 if (ti
->dim
== TD_WALLTIME
) {
460 elapsed
= time_now() - ti
->len
.t
.timer_start
;
461 if (elapsed
< 0.5 * stop
->desired
.time
) return false;
464 /* Early break in won situation. */
465 if (best
->u
.playouts
>= 2000 && tree_node_get_value(t
, 1, best
->u
.value
) >= u
->loss_threshold
)
467 /* Earlier break in super-won situation. */
468 if (best
->u
.playouts
>= 500 && tree_node_get_value(t
, 1, best
->u
.value
) >= 0.95)
471 /* Break early if we estimate the second-best move cannot
472 * catch up in assigned time anymore. We use all our time
473 * if we are in byoyomi with single stone remaining in our
474 * period, however - it's better to pre-ponder. */
475 bool time_indulgent
= (!ti
->len
.t
.main_time
&& ti
->len
.t
.byoyomi_stones
== 1);
476 if (best2
&& ti
->dim
== TD_WALLTIME
&& !time_indulgent
) {
477 double remaining
= stop
->worst
.time
- elapsed
;
478 double pps
= ((double)i
- base_playouts
) / elapsed
;
479 double estplayouts
= remaining
* pps
+ PLAYOUT_DELTA_SAFEMARGIN
;
480 if (best
->u
.playouts
> best2
->u
.playouts
+ estplayouts
) {
482 fprintf(stderr
, "Early stop, result cannot change: "
483 "best %d, best2 %d, estimated %f simulations to go\n",
484 best
->u
.playouts
, best2
->u
.playouts
, estplayouts
);
492 /* Determine whether we should terminate the search later. */
494 uct_search_keep_looking(struct uct
*u
, struct tree
*t
, struct board
*b
,
495 struct time_info
*ti
, struct time_stop
*stop
,
496 struct tree_node
*best
, struct tree_node
*best2
,
497 struct tree_node
*bestr
, struct tree_node
*winner
, int i
)
501 fprintf(stderr
, "Did not find best move, still trying...\n");
505 /* Do not waste time if we are winning. Spend up to worst time if
506 * we are unsure, but only desired time if we are sure of winning. */
507 float beta
= 2 * (tree_node_get_value(t
, 1, best
->u
.value
) - 0.5);
508 if (ti
->dim
== TD_WALLTIME
&& beta
> 0) {
509 double good_enough
= stop
->desired
.time
* beta
+ stop
->worst
.time
* (1 - beta
);
510 double elapsed
= time_now() - ti
->len
.t
.timer_start
;
511 if (elapsed
> good_enough
) return false;
514 if (u
->best2_ratio
> 0) {
515 /* Check best/best2 simulations ratio. If the
516 * two best moves give very similar results,
517 * keep simulating. */
518 if (best2
&& best2
->u
.playouts
519 && (double)best
->u
.playouts
/ best2
->u
.playouts
< u
->best2_ratio
) {
521 fprintf(stderr
, "Best2 ratio %f < threshold %f\n",
522 (double)best
->u
.playouts
/ best2
->u
.playouts
,
528 if (u
->bestr_ratio
> 0) {
529 /* Check best, best_best value difference. If the best move
530 * and its best child do not give similar enough results,
531 * keep simulating. */
532 if (bestr
&& bestr
->u
.playouts
533 && fabs((double)best
->u
.value
- bestr
->u
.value
) > u
->bestr_ratio
) {
535 fprintf(stderr
, "Bestr delta %f > threshold %f\n",
536 fabs((double)best
->u
.value
- bestr
->u
.value
),
542 if (winner
&& winner
!= best
) {
543 /* Keep simulating if best explored
544 * does not have also highest value. */
546 fprintf(stderr
, "[%d] best %3s [%d] %f != winner %3s [%d] %f\n", i
,
547 coord2sstr(best
->coord
, t
->board
),
548 best
->u
.playouts
, tree_node_get_value(t
, 1, best
->u
.value
),
549 coord2sstr(winner
->coord
, t
->board
),
550 winner
->u
.playouts
, tree_node_get_value(t
, 1, winner
->u
.value
));
554 /* No reason to keep simulating, bye. */
558 /* Run time-limited MCTS search on foreground. */
560 uct_search(struct uct
*u
, struct board
*b
, struct time_info
*ti
, enum stone color
, struct tree
*t
)
562 int base_playouts
= u
->t
->root
->u
.playouts
;
563 if (UDEBUGL(2) && base_playouts
> 0)
564 fprintf(stderr
, "<pre-simulated %d games skipped>\n", base_playouts
);
566 /* Set up time conditions. */
567 if (ti
->period
== TT_NULL
) *ti
= default_ti
;
568 struct time_stop stop
;
569 time_stop_conditions(ti
, b
, u
->fuseki_end
, u
->yose_start
, &stop
);
571 /* Number of last dynkomi adjustment. */
572 int last_dynkomi
= t
->root
->u
.playouts
;
573 /* Number of last game with progress print. */
574 int last_print
= t
->root
->u
.playouts
;
575 /* Number of simulations to wait before next print. */
576 int print_interval
= TREE_SIMPROGRESS_INTERVAL
* (u
->thread_model
== TM_ROOT
? 1 : u
->threads
);
577 /* Printed notification about full memory? */
578 bool print_fullmem
= false;
580 struct spawn_ctx
*ctx
= uct_search_start(u
, b
, color
, t
);
582 /* The search tree is ctx->t. This is normally == t, but in case of
583 * TM_ROOT, it is one of the trees belonging to the independent
584 * workers. It is important to reference ctx->t directly since the
585 * thread manager will swap the tree pointer asynchronously. */
586 /* XXX: This means TM_ROOT support is suboptimal since single stalled
587 * thread can stall the others in case of limiting the search by game
588 * count. However, TM_ROOT just does not deserve any more extra code
591 struct tree_node
*best
= NULL
;
592 struct tree_node
*best2
= NULL
; // Second-best move.
593 struct tree_node
*bestr
= NULL
; // best's best child.
594 struct tree_node
*winner
= NULL
;
596 double busywait_interval
= TREE_BUSYWAIT_INTERVAL
;
598 /* Now, just periodically poll the search tree. */
600 time_sleep(busywait_interval
);
601 /* busywait_interval should never be less than desired time, or the
602 * time control is broken. But if it happens to be less, we still search
603 * at least 100ms otherwise the move is completely random. */
605 int i
= ctx
->t
->root
->u
.playouts
;
607 /* Adjust dynkomi? */
608 if (ctx
->t
->use_extra_komi
&& u
->dynkomi
->permove
609 && u
->dynkomi_interval
610 && i
> last_dynkomi
+ u
->dynkomi_interval
) {
611 float old_dynkomi
= ctx
->t
->extra_komi
;
612 ctx
->t
->extra_komi
= u
->dynkomi
->permove(u
->dynkomi
, b
, ctx
->t
);
613 if (UDEBUGL(3) && old_dynkomi
!= ctx
->t
->extra_komi
)
614 fprintf(stderr
, "dynkomi adjusted (%f -> %f)\n", old_dynkomi
, ctx
->t
->extra_komi
);
617 /* Print progress? */
618 if (i
- last_print
> print_interval
) {
619 last_print
+= print_interval
; // keep the numbers tidy
620 uct_progress_status(u
, ctx
->t
, color
, last_print
);
622 if (!print_fullmem
&& ctx
->t
->nodes_size
> u
->max_tree_size
) {
624 fprintf(stderr
, "memory limit hit (%lu > %lu)\n", ctx
->t
->nodes_size
, u
->max_tree_size
);
625 print_fullmem
= true;
628 /* Never consider stopping if we played too few simulations.
629 * Maybe we risk losing on time when playing in super-extreme
630 * time pressure but the tree is going to be just too messed
631 * up otherwise - we might even play invalid suicides or pass
632 * when we mustn't. */
636 best
= u
->policy
->choose(u
->policy
, ctx
->t
->root
, b
, color
, resign
);
637 if (best
) best2
= u
->policy
->choose(u
->policy
, ctx
->t
->root
, b
, color
, best
->coord
);
639 /* Possibly stop search early if it's no use to try on. */
640 if (best
&& uct_search_stop_early(u
, ctx
->t
, b
, ti
, &stop
, best
, best2
, base_playouts
, i
))
643 /* Check against time settings. */
644 bool desired_done
= false;
645 if (ti
->dim
== TD_WALLTIME
) {
646 double elapsed
= time_now() - ti
->len
.t
.timer_start
;
647 if (elapsed
> stop
.worst
.time
) break;
648 desired_done
= elapsed
> stop
.desired
.time
;
650 } else { assert(ti
->dim
== TD_GAMES
);
651 if (i
> stop
.worst
.playouts
) break;
652 desired_done
= i
> stop
.desired
.playouts
;
655 /* We want to stop simulating, but are willing to keep trying
656 * if we aren't completely sure about the winner yet. */
658 if (u
->policy
->winner
&& u
->policy
->evaluate
) {
659 struct uct_descent descent
= { .node
= ctx
->t
->root
};
660 u
->policy
->winner(u
->policy
, ctx
->t
, &descent
);
661 winner
= descent
.node
;
664 bestr
= u
->policy
->choose(u
->policy
, best
, b
, stone_other(color
), resign
);
665 if (!uct_search_keep_looking(u
, ctx
->t
, b
, ti
, &stop
, best
, best2
, bestr
, winner
, i
))
669 /* TODO: Early break if best->variance goes under threshold and we already
670 * have enough playouts (possibly thanks to book or to pondering)? */
673 ctx
= uct_search_stop();
676 tree_dump(t
, u
->dumpthres
);
678 uct_progress_status(u
, t
, color
, ctx
->games
);
684 /* Start pondering background with @color to play. */
686 uct_pondering_start(struct uct
*u
, struct board
*b0
, struct tree
*t
, enum stone color
)
689 fprintf(stderr
, "Starting to ponder with color %s\n", stone2str(stone_other(color
)));
692 /* We need a local board copy to ponder upon. */
693 struct board
*b
= malloc(sizeof(*b
)); board_copy(b
, b0
);
695 /* *b0 did not have the genmove'd move played yet. */
696 struct move m
= { t
->root
->coord
, t
->root_color
};
697 int res
= board_play(b
, &m
);
699 setup_dynkomi(u
, b
, stone_other(m
.color
));
701 /* Start MCTS manager thread "headless". */
702 uct_search_start(u
, b
, color
, t
);
705 /* uct_search_stop() frontend for the pondering (non-genmove) mode. */
707 uct_pondering_stop(struct uct
*u
)
709 u
->pondering
= false;
710 if (!thread_manager_running
)
713 /* Stop the thread manager. */
714 struct spawn_ctx
*ctx
= uct_search_stop();
716 fprintf(stderr
, "(pondering) ");
717 uct_progress_status(u
, ctx
->t
, ctx
->color
, ctx
->games
);
724 uct_genmove(struct engine
*e
, struct board
*b
, struct time_info
*ti
, enum stone color
, bool pass_all_alive
)
726 double start_time
= time_now();
727 struct uct
*u
= e
->data
;
729 if (b
->superko_violation
) {
730 fprintf(stderr
, "!!! WARNING: SUPERKO VIOLATION OCCURED BEFORE THIS MOVE\n");
731 fprintf(stderr
, "Maybe you play with situational instead of positional superko?\n");
732 fprintf(stderr
, "I'm going to ignore the violation, but note that I may miss\n");
733 fprintf(stderr
, "some moves valid under this ruleset because of this.\n");
734 b
->superko_violation
= false;
738 uct_pondering_stop(u
);
739 prepare_move(e
, b
, color
);
742 /* How to decide whether to use dynkomi in this game? Since we use
743 * pondering, it's not simple "who-to-play" matter. Decide based on
744 * the last genmove issued. */
745 u
->t
->use_extra_komi
= !!(u
->dynkomi_mask
& color
);
746 setup_dynkomi(u
, b
, color
);
748 /* Make pessimistic assumption about komi for Japanese rules to
749 * avoid losing by 0.5 when winning by 0.5 with Chinese rules.
750 * The rules usually give the same winner if the integer part of komi
751 * is odd so we adjust the komi only if it is even (for a board of
752 * odd size). We are not trying to get an exact evaluation for rare
753 * cases of seki. For details see http://home.snafu.de/jasiek/parity.html
754 * TODO: Support the kgs-rules command once available. */
755 if (u
->territory_scoring
&& (((int)floor(b
->komi
) + board_size(b
)) & 1)) {
756 b
->komi
+= (color
== S_BLACK
? 1.0 : -1.0);
758 fprintf(stderr
, "Setting komi to %.1f assuming Japanese rules\n",
762 int base_playouts
= u
->t
->root
->u
.playouts
;
763 /* Perform the Monte Carlo Tree Search! */
764 int played_games
= uct_search(u
, b
, ti
, color
, u
->t
);
766 /* Choose the best move from the tree. */
767 struct tree_node
*best
= u
->policy
->choose(u
->policy
, u
->t
->root
, b
, color
, resign
);
770 return coord_copy(pass
);
773 fprintf(stderr
, "*** WINNER is %s (%d,%d) with score %1.4f (%d/%d:%d/%d games), extra komi %f\n",
774 coord2sstr(best
->coord
, b
), coord_x(best
->coord
, b
), coord_y(best
->coord
, b
),
775 tree_node_get_value(u
->t
, 1, best
->u
.value
), best
->u
.playouts
,
776 u
->t
->root
->u
.playouts
, u
->t
->root
->u
.playouts
- base_playouts
, played_games
,
779 /* Do not resign if we're so short of time that evaluation of best
780 * move is completely unreliable, we might be winning actually.
781 * In this case best is almost random but still better than resign.
782 * Also do not resign if we are getting bad results while actually
783 * giving away extra komi points (dynkomi). */
784 if (tree_node_get_value(u
->t
, 1, best
->u
.value
) < u
->resign_ratio
785 && !is_pass(best
->coord
) && best
->u
.playouts
> GJ_MINGAMES
786 && u
->t
->extra_komi
<= 1 /* XXX we assume dynamic komi == we are black */) {
788 return coord_copy(resign
);
791 /* If the opponent just passed and we win counting, always
793 if (b
->moves
> 1 && is_pass(b
->last_move
.coord
)) {
794 /* Make sure enough playouts are simulated. */
795 while (u
->ownermap
.playouts
< GJ_MINGAMES
)
796 uct_playout(u
, b
, color
, u
->t
);
797 if (uct_pass_is_safe(u
, b
, color
, u
->pass_all_alive
|| pass_all_alive
)) {
799 fprintf(stderr
, "<Will rather pass, looks safe enough.>\n");
804 tree_promote_node(u
->t
, &best
);
805 /* After a pass, pondering is harmful for two reasons:
806 * (i) We might keep pondering even when the game is over.
807 * Of course this is the case for opponent resign as well.
808 * (ii) More importantly, the ownermap will get skewed since
809 * the UCT will start cutting off any playouts. */
810 if (u
->pondering_opt
&& !is_pass(best
->coord
)) {
811 uct_pondering_start(u
, b
, u
->t
, stone_other(color
));
814 double time
= time_now() - start_time
+ 0.000001; /* avoid divide by zero */
815 fprintf(stderr
, "genmove in %0.2fs (%d games/s, %d games/s/thread)\n",
816 time
, (int)(played_games
/time
), (int)(played_games
/time
/u
->threads
));
818 return coord_copy(best
->coord
);
823 uct_genbook(struct engine
*e
, struct board
*b
, struct time_info
*ti
, enum stone color
)
825 struct uct
*u
= e
->data
;
826 if (!u
->t
) prepare_move(e
, b
, color
);
829 if (ti
->dim
== TD_GAMES
) {
830 /* Don't count in games that already went into the book. */
831 ti
->len
.games
+= u
->t
->root
->u
.playouts
;
833 uct_search(u
, b
, ti
, color
, u
->t
);
835 assert(ti
->dim
== TD_GAMES
);
836 tree_save(u
->t
, b
, ti
->len
.games
/ 100);
842 uct_dumpbook(struct engine
*e
, struct board
*b
, enum stone color
)
844 struct uct
*u
= e
->data
;
845 struct tree
*t
= tree_init(b
, color
, u
->fast_alloc
? u
->max_tree_size
: 0, u
->local_tree_aging
);
853 uct_state_init(char *arg
, struct board
*b
)
855 struct uct
*u
= calloc(1, sizeof(struct uct
));
856 bool using_elo
= false;
858 u
->debug_level
= debug_level
;
859 u
->gamelen
= MC_GAMELEN
;
863 u
->playout_amaf
= true;
864 u
->playout_amaf_nakade
= false;
865 u
->amaf_prior
= false;
866 u
->max_tree_size
= 3072ULL * 1048576;
868 u
->dynkomi_mask
= S_BLACK
;
871 u
->thread_model
= TM_TREEVL
;
872 u
->parallel_tree
= true;
873 u
->virtual_loss
= true;
875 u
->fuseki_end
= 20; // max time at 361*20% = 72 moves (our 36th move, still 99 to play)
876 u
->yose_start
= 40; // (100-40-25)*361/100/2 = 63 moves still to play by us then
877 u
->bestr_ratio
= 0.02;
878 // 2.5 is clearly too much, but seems to compensate well for overly stern time allocations.
879 // TODO: Further tuning and experiments with better time allocation schemes.
880 u
->best2_ratio
= 2.5;
882 u
->val_scale
= 0.04; u
->val_points
= 40;
885 u
->local_tree_aging
= 2;
888 char *optspec
, *next
= arg
;
891 next
+= strcspn(next
, ",");
892 if (*next
) { *next
++ = 0; } else { *next
= 0; }
894 char *optname
= optspec
;
895 char *optval
= strchr(optspec
, '=');
896 if (optval
) *optval
++ = 0;
898 if (!strcasecmp(optname
, "debug")) {
900 u
->debug_level
= atoi(optval
);
903 } else if (!strcasecmp(optname
, "mercy") && optval
) {
904 /* Minimal difference of black/white captures
905 * to stop playout - "Mercy Rule". Speeds up
906 * hopeless playouts at the expense of some
908 u
->mercymin
= atoi(optval
);
909 } else if (!strcasecmp(optname
, "gamelen") && optval
) {
910 u
->gamelen
= atoi(optval
);
911 } else if (!strcasecmp(optname
, "expand_p") && optval
) {
912 u
->expand_p
= atoi(optval
);
913 } else if (!strcasecmp(optname
, "dumpthres") && optval
) {
914 u
->dumpthres
= atoi(optval
);
915 } else if (!strcasecmp(optname
, "best2_ratio") && optval
) {
916 /* If set, prolong simulating while
917 * first_best/second_best playouts ratio
918 * is less than best2_ratio. */
919 u
->best2_ratio
= atof(optval
);
920 } else if (!strcasecmp(optname
, "bestr_ratio") && optval
) {
921 /* If set, prolong simulating while
922 * best,best_best_child values delta
923 * is more than bestr_ratio. */
924 u
->bestr_ratio
= atof(optval
);
925 } else if (!strcasecmp(optname
, "playout_amaf")) {
926 /* Whether to include random playout moves in
927 * AMAF as well. (Otherwise, only tree moves
928 * are included in AMAF. Of course makes sense
929 * only in connection with an AMAF policy.) */
930 /* with-without: 55.5% (+-4.1) */
931 if (optval
&& *optval
== '0')
932 u
->playout_amaf
= false;
934 u
->playout_amaf
= true;
935 } else if (!strcasecmp(optname
, "playout_amaf_nakade")) {
936 /* Whether to include nakade moves from playouts
937 * in the AMAF statistics; this tends to nullify
938 * the playout_amaf effect by adding too much
940 if (optval
&& *optval
== '0')
941 u
->playout_amaf_nakade
= false;
943 u
->playout_amaf_nakade
= true;
944 } else if (!strcasecmp(optname
, "playout_amaf_cutoff") && optval
) {
945 /* Keep only first N% of playout stage AMAF
947 u
->playout_amaf_cutoff
= atoi(optval
);
948 } else if ((!strcasecmp(optname
, "policy") || !strcasecmp(optname
, "random_policy")) && optval
) {
949 char *policyarg
= strchr(optval
, ':');
950 struct uct_policy
**p
= !strcasecmp(optname
, "policy") ? &u
->policy
: &u
->random_policy
;
953 if (!strcasecmp(optval
, "ucb1")) {
954 *p
= policy_ucb1_init(u
, policyarg
);
955 } else if (!strcasecmp(optval
, "ucb1amaf")) {
956 *p
= policy_ucb1amaf_init(u
, policyarg
);
958 fprintf(stderr
, "UCT: Invalid tree policy %s\n", optval
);
961 } else if (!strcasecmp(optname
, "playout") && optval
) {
962 char *playoutarg
= strchr(optval
, ':');
965 if (!strcasecmp(optval
, "moggy")) {
966 u
->playout
= playout_moggy_init(playoutarg
, b
);
967 } else if (!strcasecmp(optval
, "light")) {
968 u
->playout
= playout_light_init(playoutarg
, b
);
969 } else if (!strcasecmp(optval
, "elo")) {
970 u
->playout
= playout_elo_init(playoutarg
, b
);
973 fprintf(stderr
, "UCT: Invalid playout policy %s\n", optval
);
976 } else if (!strcasecmp(optname
, "prior") && optval
) {
977 u
->prior
= uct_prior_init(optval
, b
);
978 } else if (!strcasecmp(optname
, "amaf_prior") && optval
) {
979 u
->amaf_prior
= atoi(optval
);
980 } else if (!strcasecmp(optname
, "threads") && optval
) {
981 /* By default, Pachi will run with only single
982 * tree search thread! */
983 u
->threads
= atoi(optval
);
984 } else if (!strcasecmp(optname
, "thread_model") && optval
) {
985 if (!strcasecmp(optval
, "root")) {
986 /* Root parallelization - each thread
987 * does independent search, trees are
988 * merged at the end. */
989 u
->thread_model
= TM_ROOT
;
990 u
->parallel_tree
= false;
991 u
->virtual_loss
= false;
992 } else if (!strcasecmp(optval
, "tree")) {
993 /* Tree parallelization - all threads
994 * grind on the same tree. */
995 u
->thread_model
= TM_TREE
;
996 u
->parallel_tree
= true;
997 u
->virtual_loss
= false;
998 } else if (!strcasecmp(optval
, "treevl")) {
999 /* Tree parallelization, but also
1000 * with virtual losses - this discou-
1001 * rages most threads choosing the
1002 * same tree branches to read. */
1003 u
->thread_model
= TM_TREEVL
;
1004 u
->parallel_tree
= true;
1005 u
->virtual_loss
= true;
1007 fprintf(stderr
, "UCT: Invalid thread model %s\n", optval
);
1010 } else if (!strcasecmp(optname
, "pondering")) {
1011 /* Keep searching even during opponent's turn. */
1012 u
->pondering_opt
= !optval
|| atoi(optval
);
1013 } else if (!strcasecmp(optname
, "fuseki_end") && optval
) {
1014 /* At the very beginning it's not worth thinking
1015 * too long because the playout evaluations are
1016 * very noisy. So gradually increase the thinking
1017 * time up to maximum when fuseki_end percent
1018 * of the board has been played.
1019 * This only applies if we are not in byoyomi. */
1020 u
->fuseki_end
= atoi(optval
);
1021 } else if (!strcasecmp(optname
, "yose_start") && optval
) {
1022 /* When yose_start percent of the board has been
1023 * played, or if we are in byoyomi, stop spending
1024 * more time and spread the remaining time
1026 * Between fuseki_end and yose_start, we spend
1027 * a constant proportion of the remaining time
1028 * on each move. (yose_start should actually
1029 * be much earlier than when real yose start,
1030 * but "yose" is a good short name to convey
1032 u
->yose_start
= atoi(optval
);
1033 } else if (!strcasecmp(optname
, "force_seed") && optval
) {
1034 u
->force_seed
= atoi(optval
);
1035 } else if (!strcasecmp(optname
, "no_book")) {
1037 } else if (!strcasecmp(optname
, "dynkomi") && optval
) {
1038 /* Dynamic komi approach; there are multiple
1039 * ways to adjust komi dynamically throughout
1040 * play. We currently support two: */
1041 char *dynkomiarg
= strchr(optval
, ':');
1044 if (!strcasecmp(optval
, "none")) {
1045 u
->dynkomi
= uct_dynkomi_init_none(u
, dynkomiarg
, b
);
1046 } else if (!strcasecmp(optval
, "linear")) {
1047 u
->dynkomi
= uct_dynkomi_init_linear(u
, dynkomiarg
, b
);
1048 } else if (!strcasecmp(optval
, "adaptive")) {
1049 u
->dynkomi
= uct_dynkomi_init_adaptive(u
, dynkomiarg
, b
);
1051 fprintf(stderr
, "UCT: Invalid dynkomi mode %s\n", optval
);
1054 } else if (!strcasecmp(optname
, "dynkomi_mask") && optval
) {
1055 /* Bitmask of colors the player must be
1056 * for dynkomi be applied; you may want
1057 * to use dynkomi_mask=3 to allow dynkomi
1058 * even in games where Pachi is white. */
1059 u
->dynkomi_mask
= atoi(optval
);
1060 } else if (!strcasecmp(optname
, "dynkomi_interval") && optval
) {
1061 /* If non-zero, re-adjust dynamic komi
1062 * throughout a single genmove reading,
1063 * roughly every N simulations. */
1064 u
->dynkomi_interval
= atoi(optval
);
1065 } else if (!strcasecmp(optname
, "val_scale") && optval
) {
1066 /* How much of the game result value should be
1067 * influenced by win size. Zero means it isn't. */
1068 u
->val_scale
= atof(optval
);
1069 } else if (!strcasecmp(optname
, "val_points") && optval
) {
1070 /* Maximum size of win to be scaled into game
1071 * result value. Zero means boardsize^2. */
1072 u
->val_points
= atoi(optval
) * 2; // result values are doubled
1073 } else if (!strcasecmp(optname
, "val_extra")) {
1074 /* If false, the score coefficient will be simply
1075 * added to the value, instead of scaling the result
1076 * coefficient because of it. */
1077 u
->val_extra
= !optval
|| atoi(optval
);
1078 } else if (!strcasecmp(optname
, "local_tree") && optval
) {
1079 /* Whether to bias exploration by local tree values
1080 * (must be supported by the used policy).
1082 * 1: Do, value = result.
1083 * Try to temper the result:
1084 * 2: Do, value = 0.5+(result-expected)/2.
1085 * 3: Do, value = 0.5+bzz((result-expected)^2).
1086 * 4: Do, value = 0.5+sqrt(result-expected)/2. */
1087 u
->local_tree
= atoi(optval
);
1088 } else if (!strcasecmp(optname
, "tenuki_d") && optval
) {
1089 /* Tenuki distance at which to break the local tree. */
1090 u
->tenuki_d
= atoi(optval
);
1091 if (u
->tenuki_d
> TREE_NODE_D_MAX
+ 1) {
1092 fprintf(stderr
, "uct: tenuki_d must not be larger than TREE_NODE_D_MAX+1 %d\n", TREE_NODE_D_MAX
+ 1);
1095 } else if (!strcasecmp(optname
, "local_tree_aging") && optval
) {
1096 /* How much to reduce local tree values between moves. */
1097 u
->local_tree_aging
= atof(optval
);
1098 } else if (!strcasecmp(optname
, "local_tree_allseq")) {
1099 /* By default, only complete sequences are stored
1100 * in the local tree. If this is on, also
1101 * subsequences starting at each move are stored. */
1102 u
->local_tree_allseq
= !optval
|| atoi(optval
);
1103 } else if (!strcasecmp(optname
, "local_tree_playout")) {
1104 /* Whether to adjust ELO playout probability
1105 * distributions according to matched localtree
1107 u
->local_tree_playout
= !optval
|| atoi(optval
);
1108 } else if (!strcasecmp(optname
, "local_tree_pseqroot")) {
1109 /* By default, when we have no sequence move
1110 * to suggest in-playout, we give up. If this
1111 * is on, we make probability distribution from
1112 * sequences first moves instead. */
1113 u
->local_tree_pseqroot
= !optval
|| atoi(optval
);
1114 } else if (!strcasecmp(optname
, "pass_all_alive")) {
1115 /* Whether to consider all stones alive at the game
1116 * end instead of marking dead groupd. */
1117 u
->pass_all_alive
= !optval
|| atoi(optval
);
1118 } else if (!strcasecmp(optname
, "territory_scoring")) {
1119 /* Use territory scoring (default is area scoring).
1120 * An explicit kgs-rules command overrides this. */
1121 u
->territory_scoring
= !optval
|| atoi(optval
);
1122 } else if (!strcasecmp(optname
, "random_policy_chance") && optval
) {
1123 /* If specified (N), with probability 1/N, random_policy policy
1124 * descend is used instead of main policy descend; useful
1125 * if specified policy (e.g. UCB1AMAF) can make unduly biased
1126 * choices sometimes, you can fall back to e.g.
1127 * random_policy=UCB1. */
1128 u
->random_policy_chance
= atoi(optval
);
1129 } else if (!strcasecmp(optname
, "max_tree_size") && optval
) {
1130 /* Maximum amount of memory [MiB] consumed by the move tree.
1131 * For fast_alloc it includes the temp tree used for pruning.
1132 * Default is 3072 (3 GiB). Note that if you use TM_ROOT,
1133 * this limits size of only one of the trees, not all of them
1135 u
->max_tree_size
= atol(optval
) * 1048576;
1136 } else if (!strcasecmp(optname
, "fast_alloc")) {
1137 u
->fast_alloc
= !optval
|| atoi(optval
);
1138 } else if (!strcasecmp(optname
, "banner") && optval
) {
1139 /* Additional banner string. This must come as the
1140 * last engine parameter. */
1141 if (*next
) *--next
= ',';
1142 u
->banner
= strdup(optval
);
1145 fprintf(stderr
, "uct: Invalid engine argument %s or missing value\n", optname
);
1151 u
->resign_ratio
= 0.2; /* Resign when most games are lost. */
1152 u
->loss_threshold
= 0.85; /* Stop reading if after at least 2000 playouts this is best value. */
1154 u
->policy
= policy_ucb1amaf_init(u
, NULL
);
1156 if (!!u
->random_policy_chance
^ !!u
->random_policy
) {
1157 fprintf(stderr
, "uct: Only one of random_policy and random_policy_chance is set\n");
1161 if (!u
->local_tree
) {
1162 /* No ltree aging. */
1163 u
->local_tree_aging
= 1.0f
;
1166 u
->local_tree_playout
= false;
1168 if (u
->fast_alloc
&& !u
->parallel_tree
) {
1169 fprintf(stderr
, "fast_alloc not supported with root parallelization.\n");
1173 u
->max_tree_size
= (100ULL * u
->max_tree_size
) / (100 + MIN_FREE_MEM_PERCENT
);
1176 u
->prior
= uct_prior_init(NULL
, b
);
1179 u
->playout
= playout_moggy_init(NULL
, b
);
1180 u
->playout
->debug_level
= u
->debug_level
;
1182 u
->ownermap
.map
= malloc(board_size2(b
) * sizeof(u
->ownermap
.map
[0]));
1185 u
->dynkomi
= uct_dynkomi_init_linear(u
, NULL
, b
);
1187 /* Some things remain uninitialized for now - the opening book
1188 * is not loaded and the tree not set up. */
1189 /* This will be initialized in setup_state() at the first move
1190 * received/requested. This is because right now we are not aware
1191 * about any komi or handicap setup and such. */
1197 engine_uct_init(char *arg
, struct board
*b
)
1199 struct uct
*u
= uct_state_init(arg
, b
);
1200 struct engine
*e
= calloc(1, sizeof(struct engine
));
1201 e
->name
= "UCT Engine";
1202 e
->printhook
= uct_printhook_ownermap
;
1203 e
->notify_play
= uct_notify_play
;
1205 e
->genmove
= uct_genmove
;
1206 e
->dead_group_list
= uct_dead_group_list
;
1210 const char banner
[] = "I'm playing UCT. When I'm losing, I will resign, "
1211 "if I think I win, I play until you pass. "
1212 "Anyone can send me 'winrate' in private chat to get my assessment of the position.";
1213 if (!u
->banner
) u
->banner
= "";
1214 e
->comment
= malloc(sizeof(banner
) + strlen(u
->banner
) + 1);
1215 sprintf(e
->comment
, "%s %s", banner
, u
->banner
);