15 #include "tactics/util.h"
17 #include "uct/internal.h"
18 #include "uct/prior.h"
20 #include "uct/slave.h"
23 /* Allocate tree node(s). The returned nodes are _not_ initialized.
24 * Returns NULL if not enough memory.
25 * This function may be called by multiple threads in parallel. */
26 static struct tree_node
*
27 tree_alloc_node(struct tree
*t
, int count
, bool fast_alloc
, hash_t
*hash
)
29 struct tree_node
*n
= NULL
;
30 size_t nsize
= count
* sizeof(*n
);
31 unsigned long old_size
= __sync_fetch_and_add(&t
->nodes_size
, nsize
);
34 if (old_size
+ nsize
> t
->max_tree_size
)
36 assert(t
->nodes
!= NULL
);
37 n
= (struct tree_node
*)(t
->nodes
+ old_size
);
38 memset(n
, 0, sizeof(*n
));
40 n
= calloc2(count
, sizeof(*n
));
44 volatile static long c
= 1000000;
45 *hash
= __sync_fetch_and_add(&c
, count
);
51 /* Initialize a node at a given place in memory.
52 * This function may be called by multiple threads in parallel. */
54 tree_setup_node(struct tree
*t
, struct tree_node
*n
, coord_t coord
, int depth
, hash_t hash
)
59 if (depth
> t
->max_depth
)
63 /* Allocate and initialize a node. Returns NULL (fast_alloc mode)
64 * or exits the main program if not enough memory.
65 * This function may be called by multiple threads in parallel. */
66 static struct tree_node
*
67 tree_init_node(struct tree
*t
, coord_t coord
, int depth
, bool fast_alloc
)
71 n
= tree_alloc_node(t
, 1, fast_alloc
, &hash
);
73 tree_setup_node(t
, n
, coord
, depth
, hash
);
77 /* Create a tree structure. Pre-allocate all nodes if max_tree_size is > 0. */
79 tree_init(struct board
*board
, enum stone color
, unsigned long max_tree_size
,
80 unsigned long max_pruned_size
, unsigned long pruning_threshold
, floating_t ltree_aging
, int hbits
)
82 struct tree
*t
= calloc2(1, sizeof(*t
));
84 t
->max_tree_size
= max_tree_size
;
85 t
->max_pruned_size
= max_pruned_size
;
86 t
->pruning_threshold
= pruning_threshold
;
87 if (max_tree_size
!= 0) {
88 t
->nodes
= malloc2(max_tree_size
);
89 /* The nodes buffer doesn't need initialization. This is currently
90 * done by tree_init_node to spread the load. Doing a memset for the
91 * entire buffer here would be too slow for large trees (>10 GB). */
93 /* The root PASS move is only virtual, we never play it. */
94 t
->root
= tree_init_node(t
, pass
, 0, t
->nodes
);
95 t
->root_symmetry
= board
->symmetry
;
96 t
->root_color
= stone_other(color
); // to research black moves, root will be white
98 t
->ltree_black
= tree_init_node(t
, pass
, 0, false);
99 t
->ltree_white
= tree_init_node(t
, pass
, 0, false);
100 t
->ltree_aging
= ltree_aging
;
103 if (hbits
) t
->htable
= uct_htable_alloc(hbits
);
108 /* This function may be called by multiple threads in parallel on the
109 * same tree, but not on node n. n may be detached from the tree but
110 * must have been created in this tree originally.
111 * It returns the remaining size of the tree after n has been freed. */
113 tree_done_node(struct tree
*t
, struct tree_node
*n
)
115 struct tree_node
*ni
= n
->children
;
117 struct tree_node
*nj
= ni
->sibling
;
118 tree_done_node(t
, ni
);
122 unsigned long old_size
= __sync_fetch_and_sub(&t
->nodes_size
, sizeof(*n
));
123 return old_size
- sizeof(*n
);
131 /* Worker thread for tree_done_node_detached(). Only for fast_alloc=false. */
133 tree_done_node_worker(void *ctx_
)
135 struct subtree_ctx
*ctx
= ctx_
;
136 char *str
= coord2str(ctx
->n
->coord
, ctx
->t
->board
);
138 unsigned long tree_size
= tree_done_node(ctx
->t
, ctx
->n
);
142 fprintf(stderr
, "done freeing node at %s, tree size %lu\n", str
, tree_size
);
148 /* Asynchronously free the subtree of nodes rooted at n. If the tree becomes
149 * empty free the tree also. Only for fast_alloc=false. */
151 tree_done_node_detached(struct tree
*t
, struct tree_node
*n
)
153 if (n
->u
.playouts
< 1000) { // no thread for small tree
154 if (!tree_done_node(t
, n
))
159 pthread_attr_init(&attr
);
160 pthread_attr_setdetachstate(&attr
, PTHREAD_CREATE_DETACHED
);
163 struct subtree_ctx
*ctx
= malloc2(sizeof(struct subtree_ctx
));
166 pthread_create(&thread
, &attr
, tree_done_node_worker
, ctx
);
167 pthread_attr_destroy(&attr
);
171 tree_done(struct tree
*t
)
173 tree_done_node(t
, t
->ltree_black
);
174 tree_done_node(t
, t
->ltree_white
);
176 if (t
->htable
) free(t
->htable
);
180 } else if (!tree_done_node(t
, t
->root
)) {
182 /* A tree_done_node_worker might still be running on this tree but
183 * it will free the tree later. It is also freeing nodes faster than
184 * we will create new ones. */
190 tree_node_dump(struct tree
*tree
, struct tree_node
*node
, int l
, int thres
)
192 for (int i
= 0; i
< l
; i
++) fputc(' ', stderr
);
194 for (struct tree_node
*ni
= node
->children
; ni
; ni
= ni
->sibling
)
196 /* We use 1 as parity, since for all nodes we want to know the
197 * win probability of _us_, not the node color. */
198 fprintf(stderr
, "[%s] %.3f/%d [prior %.3f/%d amaf %.3f/%d] h=%x c#=%d <%"PRIhash
">\n",
199 coord2sstr(node
->coord
, tree
->board
),
200 tree_node_get_value(tree
, 1, node
->u
.value
), node
->u
.playouts
,
201 tree_node_get_value(tree
, 1, node
->prior
.value
), node
->prior
.playouts
,
202 tree_node_get_value(tree
, 1, node
->amaf
.value
), node
->amaf
.playouts
,
203 node
->hints
, children
, node
->hash
);
205 /* Print nodes sorted by #playouts. */
207 struct tree_node
*nbox
[1000]; int nboxl
= 0;
208 for (struct tree_node
*ni
= node
->children
; ni
; ni
= ni
->sibling
)
209 if (ni
->u
.playouts
> thres
)
214 for (int i
= 0; i
< nboxl
; i
++)
215 if (nbox
[i
] && (best
< 0 || nbox
[i
]->u
.playouts
> nbox
[best
]->u
.playouts
))
219 tree_node_dump(tree
, nbox
[best
], l
+ 1, /* node->u.value < 0.1 ? 0 : */ thres
);
225 tree_dump(struct tree
*tree
, int thres
)
227 if (thres
&& tree
->root
->u
.playouts
/ thres
> 100) {
228 /* Be a bit sensible about this; the opening tbook can create
229 * huge dumps at first. */
230 thres
= tree
->root
->u
.playouts
/ 100 * (thres
< 1000 ? 1 : thres
/ 1000);
232 fprintf(stderr
, "(UCT tree; root %s; extra komi %f; max depth %d)\n",
233 stone2str(tree
->root_color
), tree
->extra_komi
,
234 tree
->max_depth
- tree
->root
->depth
);
235 tree_node_dump(tree
, tree
->root
, 0, thres
);
237 if (DEBUGL(3) && tree
->ltree_black
) {
238 fprintf(stderr
, "B local tree:\n");
239 tree_node_dump(tree
, tree
->ltree_black
, 0, thres
);
240 fprintf(stderr
, "W local tree:\n");
241 tree_node_dump(tree
, tree
->ltree_white
, 0, thres
);
247 tree_book_name(struct board
*b
)
249 static char buf
[256];
250 if (b
->handicap
> 0) {
251 sprintf(buf
, "ucttbook-%d-%02.01f-h%d.pachitree", b
->size
- 2, b
->komi
, b
->handicap
);
253 sprintf(buf
, "ucttbook-%d-%02.01f.pachitree", b
->size
- 2, b
->komi
);
259 tree_node_save(FILE *f
, struct tree_node
*node
, int thres
)
261 bool save_children
= node
->u
.playouts
>= thres
;
264 node
->is_expanded
= 0;
267 fwrite(((void *) node
) + offsetof(struct tree_node
, depth
),
268 sizeof(struct tree_node
) - offsetof(struct tree_node
, depth
),
272 for (struct tree_node
*ni
= node
->children
; ni
; ni
= ni
->sibling
)
273 tree_node_save(f
, ni
, thres
);
276 node
->is_expanded
= 1;
283 tree_save(struct tree
*tree
, struct board
*b
, int thres
)
285 char *filename
= tree_book_name(b
);
286 FILE *f
= fopen(filename
, "wb");
291 tree_node_save(f
, tree
->root
, thres
);
298 tree_node_load(FILE *f
, struct tree_node
*node
, int *num
)
302 fread(((void *) node
) + offsetof(struct tree_node
, depth
),
303 sizeof(struct tree_node
) - offsetof(struct tree_node
, depth
),
306 /* Keep values in sane scale, otherwise we start overflowing. */
307 #define MAX_PLAYOUTS 10000000
308 if (node
->u
.playouts
> MAX_PLAYOUTS
) {
309 node
->u
.playouts
= MAX_PLAYOUTS
;
311 if (node
->amaf
.playouts
> MAX_PLAYOUTS
) {
312 node
->amaf
.playouts
= MAX_PLAYOUTS
;
314 memcpy(&node
->pu
, &node
->u
, sizeof(node
->u
));
316 struct tree_node
*ni
= NULL
, *ni_prev
= NULL
;
318 ni_prev
= ni
; ni
= calloc2(1, sizeof(*ni
));
322 ni_prev
->sibling
= ni
;
324 tree_node_load(f
, ni
, num
);
329 tree_load(struct tree
*tree
, struct board
*b
)
331 char *filename
= tree_book_name(b
);
332 FILE *f
= fopen(filename
, "rb");
336 fprintf(stderr
, "Loading opening tbook %s...\n", filename
);
340 tree_node_load(f
, tree
->root
, &num
);
341 fprintf(stderr
, "Loaded %d nodes.\n", num
);
347 /* Copy the subtree rooted at node: all nodes at or below depth
348 * or with at least threshold playouts. Only for fast_alloc.
349 * The code is destructive on src. The relative order of children of
350 * a given node is preserved (assumed by tree_get_node in particular).
351 * Returns the copy of node in the destination tree, or NULL
352 * if we could not copy it. */
353 static struct tree_node
*
354 tree_prune(struct tree
*dest
, struct tree
*src
, struct tree_node
*node
,
355 int threshold
, int depth
)
357 assert(dest
->nodes
&& node
);
358 struct tree_node
*n2
= tree_alloc_node(dest
, 1, true, NULL
);
362 if (n2
->depth
> dest
->max_depth
)
363 dest
->max_depth
= n2
->depth
;
365 n2
->is_expanded
= false;
367 if (node
->depth
>= depth
&& node
->u
.playouts
< threshold
)
369 /* For deep nodes with many playouts, we must copy all children,
370 * even those with zero playouts, because partially expanded
371 * nodes are not supported. Considering them as fully expanded
372 * would degrade the playing strength. The only exception is
373 * when dest becomes full, but this should never happen in practice
374 * if threshold is chosen to limit the number of nodes traversed. */
375 struct tree_node
*ni
= node
->children
;
378 struct tree_node
**prev2
= &(n2
->children
);
380 struct tree_node
*ni2
= tree_prune(dest
, src
, ni
, threshold
, depth
);
383 prev2
= &(ni2
->sibling
);
388 n2
->is_expanded
= true;
390 n2
->children
= NULL
; // avoid partially expanded nodes
395 /* The following constants are used for garbage collection of nodes.
396 * A tree is considered large if the top node has >= 40K playouts.
397 * For such trees, we copy deep nodes only if they have enough
398 * playouts, with a gradually increasing threshold up to 40.
399 * These constants define how much time we're willing to spend
400 * scanning the source tree when promoting a move. The chosen values
401 * make worst case pruning in about 3s for 20 GB ram, and this
402 * is only for long thinking time (>1M playouts). For fast games the
403 * trees don't grow large. For small ram or fast game we copy the
404 * entire tree. These values do not degrade playing strength and are
405 * necessary to avoid losing on time; increasing DEEP_PLAYOUTS_THRESHOLD
406 * or decreasing LARGE_TREE_PLAYOUTS will make the program faster but
408 #define LARGE_TREE_PLAYOUTS 40000LL
409 #define DEEP_PLAYOUTS_THRESHOLD 40
411 /* Garbage collect the tree early if the top node has < 5K playouts,
412 * to avoid having to do it later on a large subtree.
413 * This guarantees garbage collection in < 1s. */
414 #define SMALL_TREE_PLAYOUTS 5000
416 /* Free all the tree, keeping only the subtree rooted at node.
417 * Prune the subtree if necessary to fit in memory or
418 * to save time scanning the tree.
419 * Returns the moved node. Only for fast_alloc. */
421 tree_garbage_collect(struct tree
*tree
, struct tree_node
*node
)
423 assert(tree
->nodes
&& !node
->parent
&& !node
->sibling
);
424 double start_time
= time_now();
425 unsigned long orig_size
= tree
->nodes_size
;
427 struct tree
*temp_tree
= tree_init(tree
->board
, tree
->root_color
,
428 tree
->max_pruned_size
, 0, 0, tree
->ltree_aging
, 0);
429 temp_tree
->nodes_size
= 0; // We do not want the dummy pass node
430 struct tree_node
*temp_node
;
432 /* Find the maximum depth at which we can copy all nodes. */
434 for (struct tree_node
*ni
= node
->children
; ni
; ni
= ni
->sibling
)
436 unsigned long nodes_size
= max_nodes
* sizeof(*node
);
437 int max_depth
= node
->depth
;
438 while (nodes_size
< tree
->max_pruned_size
&& max_nodes
> 1) {
440 nodes_size
+= max_nodes
* nodes_size
;
444 /* Copy all nodes for small trees. For large trees, copy all nodes
445 * with depth <= max_depth, and all nodes with enough playouts.
446 * Avoiding going too deep (except for nodes with many playouts) is mostly
447 * to save time scanning the source tree. It can take over 20s to traverse
448 * completely a large source tree (20 GB) even without copying because
449 * the traversal is not friendly at all with the memory cache. */
450 int threshold
= (node
->u
.playouts
- LARGE_TREE_PLAYOUTS
) * DEEP_PLAYOUTS_THRESHOLD
/ LARGE_TREE_PLAYOUTS
;
451 if (threshold
< 0) threshold
= 0;
452 if (threshold
> DEEP_PLAYOUTS_THRESHOLD
) threshold
= DEEP_PLAYOUTS_THRESHOLD
;
453 temp_node
= tree_prune(temp_tree
, tree
, node
, threshold
, max_depth
);
456 /* Now copy back to original tree. */
457 tree
->nodes_size
= 0;
459 struct tree_node
*new_node
= tree_prune(tree
, temp_tree
, temp_node
, 0, temp_tree
->max_depth
);
462 double now
= time_now();
463 static double prev_time
;
464 if (!prev_time
) prev_time
= start_time
;
466 "tree pruned in %0.6g s, prev %0.3g s ago, dest depth %d wanted %d,"
467 " size %lu->%lu/%lu, playouts %d\n",
468 now
- start_time
, start_time
- prev_time
, temp_tree
->max_depth
, max_depth
,
469 orig_size
, temp_tree
->nodes_size
, tree
->max_pruned_size
, new_node
->u
.playouts
);
470 prev_time
= start_time
;
472 if (temp_tree
->nodes_size
>= temp_tree
->max_tree_size
) {
473 fprintf(stderr
, "temp tree overflow, max_tree_size %lu, pruning_threshold %lu\n",
474 tree
->max_tree_size
, tree
->pruning_threshold
);
475 /* This is not a serious problem, we will simply recompute the discarded nodes
476 * at the next move if necessary. This is better than frequently wasting memory. */
478 assert(tree
->nodes_size
== temp_tree
->nodes_size
);
479 assert(tree
->max_depth
== temp_tree
->max_depth
);
481 tree_done(temp_tree
);
486 /* Get a node of given coordinate from within parent, possibly creating it
487 * if necessary - in a very raw form (no .d, priors, ...). */
488 /* FIXME: Adjust for board symmetry. */
490 tree_get_node(struct tree
*t
, struct tree_node
*parent
, coord_t c
, bool create
)
492 if (!parent
->children
|| parent
->children
->coord
>= c
) {
493 /* Special case: Insertion at the beginning. */
494 if (parent
->children
&& parent
->children
->coord
== c
)
495 return parent
->children
;
499 struct tree_node
*nn
= tree_init_node(t
, c
, parent
->depth
+ 1, false);
500 nn
->parent
= parent
; nn
->sibling
= parent
->children
;
501 parent
->children
= nn
;
505 /* No candidate at the beginning, look through all the children. */
507 struct tree_node
*ni
;
508 for (ni
= parent
->children
; ni
->sibling
; ni
= ni
->sibling
)
509 if (ni
->sibling
->coord
>= c
)
512 if (ni
->sibling
&& ni
->sibling
->coord
== c
)
514 assert(ni
->coord
< c
);
518 struct tree_node
*nn
= tree_init_node(t
, c
, parent
->depth
+ 1, false);
519 nn
->parent
= parent
; nn
->sibling
= ni
->sibling
; ni
->sibling
= nn
;
523 /* Get local tree node corresponding to given node, given local node child
524 * iterator @lni (which points either at the corresponding node, or at the
525 * nearest local tree node after @ni). */
527 tree_lnode_for_node(struct tree
*tree
, struct tree_node
*ni
, struct tree_node
*lni
, int tenuki_d
)
529 /* Now set up lnode, which is the actual local node
530 * corresponding to ni - either lni if it is an
531 * exact match and ni is not tenuki, <pass> local
532 * node if ni is tenuki, or NULL if there is no
533 * corresponding node available. */
535 if (is_pass(ni
->coord
)) {
536 /* Also, for sanity reasons we never use local
537 * tree for passes. (Maybe we could, but it's
538 * too hard to think about.) */
542 if (lni
->coord
== ni
->coord
) {
543 /* We don't consider tenuki a sequence play
544 * that we have in local tree even though
545 * ni->d is too high; this can happen if this
546 * occured in different board topology. */
550 if (ni
->d
>= tenuki_d
) {
551 /* Tenuki, pick a pass lsibling if available. */
552 assert(lni
->parent
&& lni
->parent
->children
);
553 if (is_pass(lni
->parent
->children
->coord
)) {
554 return lni
->parent
->children
;
560 /* No corresponding local node, lnode stays NULL. */
565 /* Tree symmetry: When possible, we will localize the tree to a single part
566 * of the board in tree_expand_node() and possibly flip along symmetry axes
567 * to another part of the board in tree_promote_at(). We follow b->symmetry
568 * guidelines here. */
571 /* This function must be thread safe, given that board b is only modified by the calling thread. */
573 tree_expand_node(struct tree
*t
, struct tree_node
*node
, struct board
*b
, enum stone color
, struct uct
*u
, int parity
)
575 /* Get a Common Fate Graph distance map from parent node. */
576 int distances
[board_size2(b
)];
577 if (!is_pass(b
->last_move
.coord
) && !is_resign(b
->last_move
.coord
)) {
578 cfg_distances(b
, node
->coord
, distances
, TREE_NODE_D_MAX
);
580 // Pass or resign - everything is too far.
581 foreach_point(b
) { distances
[c
] = TREE_NODE_D_MAX
+ 1; } foreach_point_end
;
584 /* Get a map of prior values to initialize the new nodes with. */
585 struct prior_map map
= {
588 .parity
= tree_parity(t
, parity
),
589 .distances
= distances
,
591 // Include pass in the prior map.
592 struct move_stats map_prior
[board_size2(b
) + 1]; map
.prior
= &map_prior
[1];
593 bool map_consider
[board_size2(b
) + 1]; map
.consider
= &map_consider
[1];
594 memset(map_prior
, 0, sizeof(map_prior
));
595 memset(map_consider
, 0, sizeof(map_consider
));
596 map
.consider
[pass
] = true;
597 foreach_free_point(b
) {
598 assert(board_at(b
, c
) == S_NONE
);
599 if (!board_is_valid_play(b
, color
, c
))
601 map
.consider
[c
] = true;
602 } foreach_free_point_end
;
603 uct_prior(u
, node
, &map
);
605 /* Now, create the nodes. */
606 struct tree_node
*ni
= tree_init_node(t
, pass
, node
->depth
+ 1, t
->nodes
);
607 /* In fast_alloc mode we might temporarily run out of nodes but this should be rare. */
609 node
->is_expanded
= false;
612 struct tree_node
*first_child
= ni
;
614 ni
->prior
= map
.prior
[pass
]; ni
->d
= TREE_NODE_D_MAX
+ 1;
616 /* The loop considers only the symmetry playground. */
618 fprintf(stderr
, "expanding %s within [%d,%d],[%d,%d] %d-%d\n",
619 coord2sstr(node
->coord
, b
),
620 b
->symmetry
.x1
, b
->symmetry
.y1
,
621 b
->symmetry
.x2
, b
->symmetry
.y2
,
622 b
->symmetry
.type
, b
->symmetry
.d
);
624 for (int j
= b
->symmetry
.y1
; j
<= b
->symmetry
.y2
; j
++) {
625 for (int i
= b
->symmetry
.x1
; i
<= b
->symmetry
.x2
; i
++) {
627 int x
= b
->symmetry
.type
== SYM_DIAG_DOWN
? board_size(b
) - 1 - i
: i
;
630 fprintf(stderr
, "drop %d,%d\n", i
, j
);
635 coord_t c
= coord_xy(t
->board
, i
, j
);
636 if (!map
.consider
[c
]) // Filter out invalid moves
638 assert(c
!= node
->coord
); // I have spotted "C3 C3" in some sequence...
640 struct tree_node
*nj
= tree_init_node(t
, c
, node
->depth
+ 1, t
->nodes
);
642 node
->is_expanded
= false;
645 nj
->parent
= node
; ni
->sibling
= nj
; ni
= nj
;
647 ni
->prior
= map
.prior
[c
];
648 ni
->d
= distances
[c
];
651 node
->children
= first_child
; // must be done at the end to avoid race
656 flip_coord(struct board
*b
, coord_t c
,
657 bool flip_horiz
, bool flip_vert
, int flip_diag
)
659 int x
= coord_x(c
, b
), y
= coord_y(c
, b
);
661 int z
= x
; x
= y
; y
= z
;
664 x
= board_size(b
) - 1 - x
;
667 y
= board_size(b
) - 1 - y
;
669 return coord_xy(b
, x
, y
);
673 tree_fix_node_symmetry(struct board
*b
, struct tree_node
*node
,
674 bool flip_horiz
, bool flip_vert
, int flip_diag
)
676 if (!is_pass(node
->coord
))
677 node
->coord
= flip_coord(b
, node
->coord
, flip_horiz
, flip_vert
, flip_diag
);
679 for (struct tree_node
*ni
= node
->children
; ni
; ni
= ni
->sibling
)
680 tree_fix_node_symmetry(b
, ni
, flip_horiz
, flip_vert
, flip_diag
);
684 tree_fix_symmetry(struct tree
*tree
, struct board
*b
, coord_t c
)
689 struct board_symmetry
*s
= &tree
->root_symmetry
;
690 int cx
= coord_x(c
, b
), cy
= coord_y(c
, b
);
692 /* playground X->h->v->d normalization
698 bool flip_horiz
= cx
< s
->x1
|| cx
> s
->x2
;
699 bool flip_vert
= cy
< s
->y1
|| cy
> s
->y2
;
703 bool dir
= (s
->type
== SYM_DIAG_DOWN
);
704 int x
= dir
^ flip_horiz
^ flip_vert
? board_size(b
) - 1 - cx
: cx
;
705 if (flip_vert
? x
< cy
: x
> cy
) {
711 fprintf(stderr
, "%s [%d,%d -> %d,%d;%d,%d] will flip %d %d %d -> %s, sym %d (%d) -> %d (%d)\n",
713 cx
, cy
, s
->x1
, s
->y1
, s
->x2
, s
->y2
,
714 flip_horiz
, flip_vert
, flip_diag
,
715 coord2sstr(flip_coord(b
, c
, flip_horiz
, flip_vert
, flip_diag
), b
),
716 s
->type
, s
->d
, b
->symmetry
.type
, b
->symmetry
.d
);
718 if (flip_horiz
|| flip_vert
|| flip_diag
)
719 tree_fix_node_symmetry(b
, tree
->root
, flip_horiz
, flip_vert
, flip_diag
);
724 tree_unlink_node(struct tree_node
*node
)
726 struct tree_node
*ni
= node
->parent
;
727 if (ni
->children
== node
) {
728 ni
->children
= node
->sibling
;
731 while (ni
->sibling
!= node
)
733 ni
->sibling
= node
->sibling
;
735 node
->sibling
= NULL
;
739 /* Reduce weight of statistics on promotion. Remove nodes that
740 * get reduced to zero playouts; returns next node to consider
741 * in the children list (@node may get deleted). */
742 static struct tree_node
*
743 tree_age_node(struct tree
*tree
, struct tree_node
*node
)
745 node
->u
.playouts
/= tree
->ltree_aging
;
746 if (node
->parent
&& !node
->u
.playouts
) {
747 struct tree_node
*sibling
= node
->sibling
;
748 /* Delete node, no playouts. */
749 tree_unlink_node(node
);
750 tree_done_node(tree
, node
);
754 struct tree_node
*ni
= node
->children
;
755 while (ni
) ni
= tree_age_node(tree
, ni
);
756 return node
->sibling
;
759 /* Promotes the given node as the root of the tree. In the fast_alloc
760 * mode, the node may be moved and some of its subtree may be pruned. */
762 tree_promote_node(struct tree
*tree
, struct tree_node
**node
)
764 assert((*node
)->parent
== tree
->root
);
765 tree_unlink_node(*node
);
767 /* Freeing the rest of the tree can take several seconds on large
768 * trees, so we must do it asynchronously: */
769 tree_done_node_detached(tree
, tree
->root
);
771 /* Garbage collect if we run out of memory, or it is cheap to do so now: */
772 if (tree
->nodes_size
>= tree
->pruning_threshold
773 || (tree
->nodes_size
>= tree
->max_tree_size
/ 10 && (*node
)->u
.playouts
< SMALL_TREE_PLAYOUTS
))
774 *node
= tree_garbage_collect(tree
, *node
);
777 tree
->root_color
= stone_other(tree
->root_color
);
779 board_symmetry_update(tree
->board
, &tree
->root_symmetry
, (*node
)->coord
);
780 /* See tree.score description for explanation on why don't we zero
781 * score on node promotion. */
782 // tree->score.playouts = 0;
784 /* If the tree deepest node was under node, or if we called tree_garbage_collect,
785 * tree->max_depth is correct. Otherwise we could traverse the tree
786 * to recompute max_depth but it's not worth it: it's just for debugging
787 * and soon the tree will grow and max_depth will become correct again. */
789 if (tree
->ltree_aging
!= 1.0f
) { // XXX: != should work here even with the floating_t
790 tree_age_node(tree
, tree
->ltree_black
);
791 tree_age_node(tree
, tree
->ltree_white
);
796 tree_promote_at(struct tree
*tree
, struct board
*b
, coord_t c
)
798 tree_fix_symmetry(tree
, b
, c
);
800 for (struct tree_node
*ni
= tree
->root
->children
; ni
; ni
= ni
->sibling
) {
801 if (ni
->coord
== c
) {
802 tree_promote_node(tree
, &ni
);