4 * Userspace RCU library - Red-Black Tree
6 * Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 * Implementation of RCU-adapted data structures and operations based on the RB
23 * tree algorithms found in chapter 12 of:
25 * Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and
26 * Clifford Stein. Introduction to Algorithms, Third Edition. The MIT
27 * Press, September 2009.
39 #include <urcu/rcurbtree.h>
40 #include <urcu-pointer.h>
41 #include <urcu-call-rcu.h>
42 #include <urcu/compiler.h>
45 #define dbg_printf(args...) printf(args)
46 #define dbg_usleep(usecs) usleep(usecs)
48 #define dbg_printf(args...)
49 #define dbg_usleep(usecs)
53 * Undefine this to enable the non-RCU rotate and transplant functions
56 #define RBTREE_RCU_SUPPORT_ROTATE_LEFT
57 #define RBTREE_RCU_SUPPORT_ROTATE_RIGHT
58 #define RBTREE_RCU_SUPPORT_TRANSPLANT
61 static pthread_mutex_t test_mutex
= PTHREAD_MUTEX_INITIALIZER
;
62 static pthread_mutex_t outer_mutex
= PTHREAD_MUTEX_INITIALIZER
;
65 void lock_outer_mutex(void)
67 pthread_mutex_lock(&outer_mutex
);
71 void unlock_outer_mutex(void)
73 pthread_mutex_unlock(&outer_mutex
);
77 void lock_test_mutex(void)
79 pthread_mutex_lock(&test_mutex
);
83 void unlock_test_mutex(void)
85 pthread_mutex_unlock(&test_mutex
);
90 void set_parent(struct rcu_rbtree_node
*node
,
91 struct rcu_rbtree_node
*parent
,
94 _CMM_STORE_SHARED(node
->parent
, ((unsigned long) parent
) | pos
);
98 struct rcu_rbtree_node
*get_parent(struct rcu_rbtree_node
*node
)
100 return (struct rcu_rbtree_node
*) (node
->parent
& ~1UL);
104 unsigned int get_pos(struct rcu_rbtree_node
*node
)
106 return (unsigned int) (node
->parent
& 1UL);
110 struct rcu_rbtree_node
*get_parent_and_pos(struct rcu_rbtree_node
*node
,
113 unsigned long parent_pos
= rcu_dereference(node
->parent
);
115 *pos
= (unsigned int) (parent_pos
& 1UL);
116 return (struct rcu_rbtree_node
*) (parent_pos
& ~1UL);
120 void set_decay(struct rcu_rbtree_node
*x
, struct rcu_rbtree_node
*xc
)
126 struct rcu_rbtree_node
*get_decay(struct rcu_rbtree_node
*x
)
130 while (x
->decay_next
)
136 struct rcu_rbtree_node
*is_decay(struct rcu_rbtree_node
*x
)
138 return x
->decay_next
;
142 struct rcu_rbtree_node
*dup_decay_node(struct rcu_rbtree
*rbtree
,
143 struct rcu_rbtree_node
*x
)
145 struct rcu_rbtree_node
*xc
;
147 if (rcu_rbtree_is_nil(rbtree
, x
))
150 xc
= rbtree
->rballoc();
151 memcpy(xc
, x
, sizeof(struct rcu_rbtree_node
));
152 xc
->decay_next
= NULL
;
154 call_rcu(&x
->head
, rbtree
->rbfree
);
159 * Info for range lookups:
160 * Range lookup information is only valid when used when searching for
161 * ranges. It should never be used in next/prev traversal because the
162 * pointers to parents are not in sync with the parent vision of the
166 void set_left(struct rcu_rbtree
*rbtree
, struct rcu_rbtree_node
*node
,
167 struct rcu_rbtree_node
*left
)
173 void set_right(struct rcu_rbtree
*rbtree
, struct rcu_rbtree_node
*node
,
174 struct rcu_rbtree_node
*right
)
176 node
->_right
= right
;
181 * Deal with memory allocation errors.
182 * Can be ensured by reserving a pool of memory entries before doing the
183 * insertion, which will have to be function of number of
184 * transplantations/rotations required for the operation.
189 void show_tree(struct rcu_rbtree
*rbtree
)
191 struct rcu_rbtree_node
*node
;
193 node
= rcu_rbtree_min(rbtree
, rbtree
->root
);
194 while (!rcu_rbtree_is_nil(rbtree
, node
)) {
195 assert(!is_decay(node
));
196 printf("{ b:%lX e:%lX pb: %lX pe: %lX r:%lX l:%lX %s %s %s} ",
197 (unsigned long) node
->begin
,
198 (unsigned long) node
->end
,
199 (unsigned long) get_parent(node
)->begin
,
200 (unsigned long) get_parent(node
)->end
,
201 (unsigned long) node
->_right
->key
,
202 (unsigned long) node
->_left
->key
,
203 node
->color
? "red" : "black",
204 get_pos(node
) ? "right" : "left",
205 rcu_rbtree_is_nil(rbtree
, node
) ? "nil" : "");
206 node
= rcu_rbtree_next(rbtree
, node
);
212 void show_tree(struct rcu_rbtree
*rbtree
)
218 struct rcu_rbtree_node
*make_nil(struct rcu_rbtree
*rbtree
)
220 return &rbtree
->nil_node
;
224 * Iterative rbtree search.
226 struct rcu_rbtree_node
*rcu_rbtree_search(struct rcu_rbtree
*rbtree
,
227 struct rcu_rbtree_node
*x
,
230 x
= rcu_dereference(x
);
233 while (!rcu_rbtree_is_nil(rbtree
, x
) && (comp
= rbtree
->comp(k
, x
->begin
)) != 0) {
236 x
= rcu_dereference(x
->_left
);
238 x
= rcu_dereference(x
->_right
);
244 struct rcu_rbtree_node
*rcu_rbtree_min_dup_decay(struct rcu_rbtree
*rbtree
,
245 struct rcu_rbtree_node
*x
,
246 struct rcu_rbtree_node
**zr
)
248 struct rcu_rbtree_node
*xl
;
250 x
= rcu_dereference(x
);
252 if (rcu_rbtree_is_nil(rbtree
, x
)) {
256 *zr
= x
= dup_decay_node(rbtree
, x
);
258 while (!rcu_rbtree_is_nil(rbtree
, xl
= rcu_dereference(x
->_left
))) {
259 x
= dup_decay_node(rbtree
, xl
);
260 set_parent(x
, get_decay(get_parent(x
)), get_pos(x
));
261 get_parent(x
)->_left
= get_decay(get_parent(x
)->_left
);
267 struct rcu_rbtree_node
*rcu_rbtree_min_update_decay(struct rcu_rbtree
*rbtree
,
268 struct rcu_rbtree_node
*x
)
270 struct rcu_rbtree_node
*xl
;
272 x
= rcu_dereference(x
);
274 if (rcu_rbtree_is_nil(rbtree
, x
))
277 set_parent(x
->_right
, get_decay(get_parent(x
->_right
)),
279 set_parent(x
->_left
, get_decay(get_parent(x
->_left
)),
283 while (!rcu_rbtree_is_nil(rbtree
, xl
= rcu_dereference(x
->_left
))) {
285 set_parent(x
->_right
, get_decay(get_parent(x
->_right
)),
287 set_parent(x
->_left
, get_decay(get_parent(x
->_left
)),
293 struct rcu_rbtree_node
*rcu_rbtree_min(struct rcu_rbtree
*rbtree
,
294 struct rcu_rbtree_node
*x
)
296 struct rcu_rbtree_node
*xl
;
298 x
= rcu_dereference(x
);
300 if (rcu_rbtree_is_nil(rbtree
, x
))
303 while (!rcu_rbtree_is_nil(rbtree
, xl
= rcu_dereference(x
->_left
)))
308 struct rcu_rbtree_node
*rcu_rbtree_max(struct rcu_rbtree
*rbtree
,
309 struct rcu_rbtree_node
*x
)
311 struct rcu_rbtree_node
*xr
;
313 x
= rcu_dereference(x
);
315 if (rcu_rbtree_is_nil(rbtree
, x
))
318 while (!rcu_rbtree_is_nil(rbtree
, xr
= rcu_dereference(x
->_right
)))
325 * Updates should wait for a grace period between update of the
326 * redirect pointer and update of the parent child pointer. This is to make sure
327 * that no reference to the old entry exist.
331 * RCU read lock must be held across the next/prev calls to ensure validity of
334 struct rcu_rbtree_node
*rcu_rbtree_next(struct rcu_rbtree
*rbtree
,
335 struct rcu_rbtree_node
*x
)
337 struct rcu_rbtree_node
*xr
, *y
;
340 x
= rcu_dereference(x
);
342 if (!rcu_rbtree_is_nil(rbtree
, xr
= rcu_dereference(x
->_right
)))
343 return rcu_rbtree_min(rbtree
, xr
);
344 y
= get_parent_and_pos(x
, &x_pos
);
345 while (!rcu_rbtree_is_nil(rbtree
, y
) && x_pos
== IS_RIGHT
) {
347 y
= get_parent_and_pos(y
, &x_pos
);
352 struct rcu_rbtree_node
*rcu_rbtree_prev(struct rcu_rbtree
*rbtree
,
353 struct rcu_rbtree_node
*x
)
355 struct rcu_rbtree_node
*xl
, *y
;
358 x
= rcu_dereference(x
);
360 if (!rcu_rbtree_is_nil(rbtree
, xl
= rcu_dereference(x
->_left
)))
361 return rcu_rbtree_max(rbtree
, xl
);
362 y
= get_parent_and_pos(x
, &x_pos
);
363 while (!rcu_rbtree_is_nil(rbtree
, y
) && x_pos
== IS_LEFT
) {
365 y
= get_parent_and_pos(y
, &x_pos
);
371 * We have to ensure these assumptions are correct for prev/next
374 * with x being a right child, the assumption that:
375 * get_parent(x)->_right == x
376 * or if x is a left child, the assumption that:
377 * get_parent(x)->_left == x
379 * This explains why we have to allocate a vc copy of the node for left_rotate,
380 * right_rotate and transplant operations.
382 * We always ensure that the right/left child and correct parent is set in the
383 * node copies *before* we reparent the children and make the upper-level point
387 /* RCU: copy x and y, atomically point to new versions. GC old. */
388 /* Should be eventually followed by a cmm_smp_wmc() */
390 #ifdef RBTREE_RCU_SUPPORT_ROTATE_LEFT
393 void left_rotate(struct rcu_rbtree
*rbtree
,
394 struct rcu_rbtree_node
*x
)
396 struct rcu_rbtree_node
*y
, *y_left
;
401 /* Now operate on new copy, decay old versions */
402 x
= dup_decay_node(rbtree
, x
);
403 y
= dup_decay_node(rbtree
, y
);
404 y_left
= dup_decay_node(rbtree
, y_left
);
406 /* Internal node modifications */
407 set_parent(y
, get_parent(x
), get_pos(x
));
408 set_parent(x
, y
, IS_LEFT
);
409 set_left(rbtree
, y
, x
);
410 set_right(rbtree
, x
, y_left
);
412 if (!rcu_rbtree_is_nil(rbtree
, y_left
))
413 set_parent(y_left
, x
, IS_RIGHT
);
415 cmm_smp_wmb(); /* write into node before publish */
417 /* External references update (visible by readers) */
418 if (rcu_rbtree_is_nil(rbtree
, get_parent(y
)))
419 _CMM_STORE_SHARED(rbtree
->root
, y
);
420 else if (get_pos(y
) == IS_LEFT
)
421 _CMM_STORE_SHARED(get_parent(y
)->_left
, y
);
423 _CMM_STORE_SHARED(get_parent(y
)->_right
, y
);
425 /* Point children to new copy (parent only used by updates/next/prev) */
426 set_parent(x
->_left
, get_decay(get_parent(x
->_left
)),
428 set_parent(y
->_right
, get_decay(get_parent(y
->_right
)),
430 if (!rcu_rbtree_is_nil(rbtree
, y_left
)) {
431 set_parent(y_left
->_right
,
432 get_decay(get_parent(y_left
->_right
)),
433 get_pos(y_left
->_right
));
434 set_parent(y_left
->_left
,
435 get_decay(get_parent(y_left
->_left
)),
436 get_pos(y_left
->_left
));
440 assert(y
== rbtree
->root
|| get_parent(y
)->_left
== y
441 || get_parent(y
)->_right
== y
);
442 assert(x
== rbtree
->root
|| get_parent(x
)->_left
== x
443 || get_parent(x
)->_right
== x
);
444 assert(rcu_rbtree_is_nil(rbtree
, x
->_right
) || get_parent(x
->_right
) == x
);
445 assert(rcu_rbtree_is_nil(rbtree
, x
->_left
) || get_parent(x
->_left
) == x
);
446 assert(rcu_rbtree_is_nil(rbtree
, y
->_right
) || get_parent(y
->_right
) == y
);
447 assert(rcu_rbtree_is_nil(rbtree
, y
->_left
) || get_parent(y
->_left
) == y
);
448 assert(!is_decay(rbtree
->root
));
449 assert(!is_decay(x
));
450 assert(!is_decay(y
));
451 assert(!is_decay(x
->_right
));
452 assert(!is_decay(x
->_left
));
453 assert(!is_decay(y
->_right
));
454 assert(!is_decay(y
->_left
));
459 /* non-rcu version */
461 void left_rotate(struct rcu_rbtree
*rbtree
,
462 struct rcu_rbtree_node
*x
)
464 struct rcu_rbtree_node
*y
;
468 x
->_right
= y
->_left
;
469 if (!rcu_rbtree_is_nil(rbtree
, y
->_left
))
470 set_parent(y
->_left
, x
, IS_RIGHT
);
471 set_parent(y
, get_parent(x
), get_pos(x
));
472 if (rcu_rbtree_is_nil(rbtree
, get_parent(x
)))
474 else if (x
== get_parent(x
)->_left
) {
475 get_parent(x
)->_left
= y
;
477 get_parent(x
)->_right
= y
;
480 set_parent(x
, y
, IS_LEFT
);
486 #ifdef RBTREE_RCU_SUPPORT_ROTATE_RIGHT
488 void right_rotate(struct rcu_rbtree
*rbtree
,
489 struct rcu_rbtree_node
*x
)
491 struct rcu_rbtree_node
*y
, *y_right
;
496 /* Now operate on new copy, decay old versions */
497 x
= dup_decay_node(rbtree
, x
);
498 y
= dup_decay_node(rbtree
, y
);
499 y_right
= dup_decay_node(rbtree
, y_right
);
501 /* Internal node modifications */
502 set_parent(y
, get_parent(x
), get_pos(x
));
503 set_parent(x
, y
, IS_RIGHT
);
504 set_right(rbtree
, y
, x
);
505 set_left(rbtree
, x
, y_right
);
507 if (!rcu_rbtree_is_nil(rbtree
, y_right
))
508 set_parent(y_right
, x
, IS_LEFT
);
510 cmm_smp_wmb(); /* write into node before publish */
512 /* External references update (visible by readers) */
513 if (rcu_rbtree_is_nil(rbtree
, get_parent(y
)))
514 _CMM_STORE_SHARED(rbtree
->root
, y
);
515 else if (get_pos(y
) == IS_RIGHT
)
516 _CMM_STORE_SHARED(get_parent(y
)->_right
, y
);
518 _CMM_STORE_SHARED(get_parent(y
)->_left
, y
);
520 /* Point children to new copy (parent only used by updates/next/prev) */
521 set_parent(x
->_right
, get_decay(get_parent(x
->_right
)),
523 set_parent(y
->_left
, get_decay(get_parent(y
->_left
)),
525 if (!rcu_rbtree_is_nil(rbtree
, y_right
)) {
526 set_parent(y_right
->_left
,
527 get_decay(get_parent(y_right
->_left
)),
528 get_pos(y_right
->_left
));
529 set_parent(y_right
->_right
,
530 get_decay(get_parent(y_right
->_right
)),
531 get_pos(y_right
->_right
));
535 assert(y
== rbtree
->root
|| get_parent(y
)->_right
== y
536 || get_parent(y
)->_left
== y
);
537 assert(x
== rbtree
->root
|| get_parent(x
)->_right
== x
538 || get_parent(x
)->_left
== x
);
539 assert(rcu_rbtree_is_nil(rbtree
, x
->_left
) || get_parent(x
->_left
) == x
);
540 assert(rcu_rbtree_is_nil(rbtree
, x
->_right
) || get_parent(x
->_right
) == x
);
541 assert(rcu_rbtree_is_nil(rbtree
, y
->_left
) || get_parent(y
->_left
) == y
);
542 assert(rcu_rbtree_is_nil(rbtree
, y
->_right
) || get_parent(y
->_right
) == y
);
543 assert(!is_decay(rbtree
->root
));
544 assert(!is_decay(x
));
545 assert(!is_decay(y
));
546 assert(!is_decay(x
->_left
));
547 assert(!is_decay(x
->_right
));
548 assert(!is_decay(y
->_left
));
549 assert(!is_decay(y
->_right
));
554 /* non-rcu version */
556 void right_rotate(struct rcu_rbtree
*rbtree
,
557 struct rcu_rbtree_node
*x
)
559 struct rcu_rbtree_node
*y
;
563 x
->_left
= y
->_right
;
564 if (!rcu_rbtree_is_nil(rbtree
, y
->_right
))
565 set_parent(y
->_right
, x
, IS_LEFT
);
566 set_parent(y
, get_parent(x
), get_pos(x
));
567 if (rcu_rbtree_is_nil(rbtree
, get_parent(x
)))
569 else if (x
== get_parent(x
)->_right
) {
570 get_parent(x
)->_right
= y
;
572 get_parent(x
)->_left
= y
;
575 set_parent(x
, y
, IS_RIGHT
);
581 static void rcu_rbtree_insert_fixup(struct rcu_rbtree
*rbtree
,
582 struct rcu_rbtree_node
*z
)
584 struct rcu_rbtree_node
*y
;
586 dbg_printf("insert fixup %p\n", z
->begin
);
587 assert(!is_decay(rbtree
->root
));
589 while (get_parent(z
)->color
== COLOR_RED
) {
590 if (get_parent(z
) == get_parent(get_parent(z
))->_left
) {
591 y
= get_parent(get_parent(z
))->_right
;
592 if (y
->color
== COLOR_RED
) {
593 get_parent(z
)->color
= COLOR_BLACK
;
594 y
->color
= COLOR_BLACK
;
595 get_parent(get_parent(z
))->color
= COLOR_RED
;
596 z
= get_parent(get_parent(z
));
598 if (z
== get_parent(z
)->_right
) {
600 left_rotate(rbtree
, z
);
602 assert(!is_decay(rbtree
->root
));
604 get_parent(z
)->color
= COLOR_BLACK
;
605 get_parent(get_parent(z
))->color
= COLOR_RED
;
606 assert(!is_decay(z
));
607 assert(!is_decay(get_parent(z
)));
608 assert(!is_decay(get_parent(get_parent(z
))));
609 right_rotate(rbtree
, get_parent(get_parent(z
)));
610 assert(!is_decay(z
));
611 assert(!is_decay(rbtree
->root
));
614 y
= get_parent(get_parent(z
))->_left
;
615 if (y
->color
== COLOR_RED
) {
616 get_parent(z
)->color
= COLOR_BLACK
;
617 y
->color
= COLOR_BLACK
;
618 get_parent(get_parent(z
))->color
= COLOR_RED
;
619 z
= get_parent(get_parent(z
));
621 if (z
== get_parent(z
)->_left
) {
623 right_rotate(rbtree
, z
);
625 assert(!is_decay(rbtree
->root
));
627 get_parent(z
)->color
= COLOR_BLACK
;
628 get_parent(get_parent(z
))->color
= COLOR_RED
;
629 left_rotate(rbtree
, get_parent(get_parent(z
)));
630 assert(!is_decay(z
));
631 assert(!is_decay(rbtree
->root
));
635 rbtree
->root
->color
= COLOR_BLACK
;
639 * rcu_rbtree_insert - Insert a node in the RCU rbtree
641 * Returns 0 on success, or < 0 on error.
643 int rcu_rbtree_insert(struct rcu_rbtree
*rbtree
,
644 struct rcu_rbtree_node
*z
)
646 struct rcu_rbtree_node
*x
, *y
;
648 dbg_printf("insert %p\n", z
->begin
);
649 assert(!is_decay(rbtree
->root
));
651 y
= make_nil(rbtree
);
653 while (!rcu_rbtree_is_nil(rbtree
, x
)) {
655 if (rbtree
->comp(z
->begin
, x
->begin
) < 0)
661 z
->_left
= make_nil(rbtree
);
662 z
->_right
= make_nil(rbtree
);
663 z
->color
= COLOR_RED
;
664 z
->decay_next
= NULL
;
667 if (rcu_rbtree_is_nil(rbtree
, y
))
668 set_parent(z
, y
, IS_RIGHT
); /* pos arbitrary for root node */
669 else if (rbtree
->comp(z
->begin
, y
->begin
) < 0)
670 set_parent(z
, y
, IS_LEFT
);
672 set_parent(z
, y
, IS_RIGHT
);
674 if (rcu_rbtree_is_nil(rbtree
, y
)) {
676 * Order stores to z (children/parents) before stores
677 * that will make it visible to the rest of the tree.
680 _CMM_STORE_SHARED(rbtree
->root
, z
);
681 } else if (rbtree
->comp(z
->begin
, y
->begin
) < 0) {
683 * Order stores to z (children/parents) before stores
684 * that will make it visible to the rest of the tree.
687 if (rcu_rbtree_is_nil(rbtree
, y
))
688 _CMM_STORE_SHARED(rbtree
->root
, z
);
689 else if (get_pos(z
) == IS_LEFT
)
690 _CMM_STORE_SHARED(y
->_left
, z
);
692 _CMM_STORE_SHARED(y
->_right
, z
);
695 * Order stores to z (children/parents) before stores
696 * that will make it visible to the rest of the tree.
699 if (rcu_rbtree_is_nil(rbtree
, y
))
700 _CMM_STORE_SHARED(rbtree
->root
, z
);
701 else if (get_pos(z
) == IS_LEFT
)
702 _CMM_STORE_SHARED(y
->_left
, z
);
704 _CMM_STORE_SHARED(y
->_right
, z
);
706 rcu_rbtree_insert_fixup(rbtree
, z
);
708 * Make sure to commit all _CMM_STORE_SHARED() for non-coherent caches.
717 * Transplant v into u position.
720 #ifdef RBTREE_RCU_SUPPORT_TRANSPLANT
723 void rcu_rbtree_transplant(struct rcu_rbtree
*rbtree
,
724 struct rcu_rbtree_node
*u
,
725 struct rcu_rbtree_node
*v
,
726 unsigned int copy_parents
)
728 dbg_printf("transplant %p\n", v
->begin
);
730 if (!rcu_rbtree_is_nil(rbtree
, v
))
731 v
= dup_decay_node(rbtree
, v
);
733 if (rcu_rbtree_is_nil(rbtree
, get_parent(u
))) {
734 /* pos is arbitrary for root node */
735 set_parent(v
, get_parent(u
), IS_RIGHT
);
736 cmm_smp_wmb(); /* write into node before publish */
737 _CMM_STORE_SHARED(rbtree
->root
, v
);
739 set_parent(v
, get_parent(u
), get_pos(u
));
740 cmm_smp_wmb(); /* write into node before publish */
742 if (rcu_rbtree_is_nil(rbtree
, get_parent(u
)))
743 _CMM_STORE_SHARED(rbtree
->root
, v
);
744 else if (get_pos(u
) == IS_LEFT
)
745 _CMM_STORE_SHARED(get_parent(u
)->_left
, v
);
747 _CMM_STORE_SHARED(get_parent(u
)->_right
, v
);
750 /* Point children to new copy (parent only used by updates/next/prev) */
751 if (!rcu_rbtree_is_nil(rbtree
, v
)) {
752 set_parent(v
->_right
, get_decay(get_parent(v
->_right
)),
754 set_parent(v
->_left
, get_decay(get_parent(v
->_left
)),
757 assert(!is_decay(rbtree
->root
));
762 /* Non-RCU version */
764 void rcu_rbtree_transplant(struct rcu_rbtree
*rbtree
,
765 struct rcu_rbtree_node
*u
,
766 struct rcu_rbtree_node
*v
,
767 unsigned int copy_parents
)
769 dbg_printf("transplant %p\n", v
->begin
);
772 if (rcu_rbtree_is_nil(rbtree
, get_parent(u
)))
774 else if (u
== get_parent(u
)->_left
)
775 get_parent(u
)->_left
= v
;
777 get_parent(u
)->_right
= v
;
778 set_parent(v
, get_parent(u
), get_pos(u
));
784 static void rcu_rbtree_remove_fixup(struct rcu_rbtree
*rbtree
,
785 struct rcu_rbtree_node
*x
)
787 dbg_printf("remove fixup %p\n", x
->begin
);
789 while (x
!= rbtree
->root
&& x
->color
== COLOR_BLACK
) {
790 assert(!is_decay(get_parent(x
)));
791 assert(!is_decay(get_parent(x
)->_left
));
792 if (x
== get_parent(x
)->_left
) {
793 struct rcu_rbtree_node
*w
;
795 w
= get_parent(x
)->_right
;
797 if (w
->color
== COLOR_RED
) {
798 w
->color
= COLOR_BLACK
;
799 get_parent(x
)->color
= COLOR_RED
;
800 left_rotate(rbtree
, get_parent(x
));
802 assert(!is_decay(rbtree
->root
));
803 w
= get_parent(x
)->_right
;
805 if (w
->_left
->color
== COLOR_BLACK
806 && w
->_right
->color
== COLOR_BLACK
) {
807 w
->color
= COLOR_RED
;
809 assert(!is_decay(rbtree
->root
));
810 assert(!is_decay(x
));
812 if (w
->_right
->color
== COLOR_BLACK
) {
813 w
->_left
->color
= COLOR_BLACK
;
814 w
->color
= COLOR_RED
;
815 right_rotate(rbtree
, w
);
816 assert(!is_decay(rbtree
->root
));
818 w
= get_parent(x
)->_right
;
820 w
->color
= get_parent(x
)->color
;
821 get_parent(x
)->color
= COLOR_BLACK
;
822 w
->_right
->color
= COLOR_BLACK
;
823 left_rotate(rbtree
, get_parent(x
));
824 assert(!is_decay(rbtree
->root
));
828 struct rcu_rbtree_node
*w
;
830 w
= get_parent(x
)->_left
;
832 if (w
->color
== COLOR_RED
) {
833 w
->color
= COLOR_BLACK
;
834 get_parent(x
)->color
= COLOR_RED
;
835 right_rotate(rbtree
, get_parent(x
));
836 assert(!is_decay(rbtree
->root
));
838 w
= get_parent(x
)->_left
;
840 if (w
->_right
->color
== COLOR_BLACK
841 && w
->_left
->color
== COLOR_BLACK
) {
842 w
->color
= COLOR_RED
;
844 assert(!is_decay(rbtree
->root
));
845 assert(!is_decay(x
));
847 if (w
->_left
->color
== COLOR_BLACK
) {
848 w
->_right
->color
= COLOR_BLACK
;
849 w
->color
= COLOR_RED
;
850 left_rotate(rbtree
, w
);
851 assert(!is_decay(rbtree
->root
));
853 w
= get_parent(x
)->_left
;
855 w
->color
= get_parent(x
)->color
;
856 get_parent(x
)->color
= COLOR_BLACK
;
857 w
->_left
->color
= COLOR_BLACK
;
858 right_rotate(rbtree
, get_parent(x
));
859 assert(!is_decay(rbtree
->root
));
864 x
->color
= COLOR_BLACK
;
868 * Delete z. All non-copied children left/right positions are unchanged.
871 void rcu_rbtree_remove_nonil(struct rcu_rbtree
*rbtree
,
872 struct rcu_rbtree_node
*z
,
873 struct rcu_rbtree_node
*y
)
875 struct rcu_rbtree_node
*x
;
877 dbg_printf("remove nonil %p\n", z
->begin
);
880 assert(!is_decay(z
));
881 assert(!is_decay(y
));
882 assert(!is_decay(y
->_right
));
883 assert(!is_decay(get_parent(y
)));
885 assert(!is_decay(x
));
886 if (get_parent(y
) == z
) {
887 y
= dup_decay_node(rbtree
, y
);
888 set_parent(x
, y
, get_pos(x
)); /* parent for nil */
889 /* y is z's right node: set left will just update y */
890 set_left(rbtree
, y
, z
->_left
);
891 rcu_rbtree_transplant(rbtree
, z
, y
, 1);
893 struct rcu_rbtree_node
*oy_right
, *z_right
;
896 * Need to make sure y is always visible by readers.
898 y
= rcu_rbtree_min_dup_decay(rbtree
, z
->_right
, &z_right
);
899 assert(!is_decay(y
));
900 assert(!is_decay(z
));
901 oy_right
= y
->_right
;
904 * The max child begin of z_right does not change, because
905 * we're only changing its left children.
908 set_parent(y
->_right
, y
, IS_RIGHT
);
909 assert(!is_decay(z
->_left
));
911 assert(!is_decay(oy_right
));
913 * Transplant of oy_right to old y's location will only
914 * trigger a min/max update of the already copied branch
915 * (which is not visible yet). We are transplanting
916 * oy_right as a left child of old y's parent, so the
917 * min values update propagated upward necessarily stops
920 rcu_rbtree_transplant(rbtree
, y
, oy_right
, 0);
921 rcu_rbtree_transplant(rbtree
, z
, y
, 1);
922 /* Update children */
923 (void) rcu_rbtree_min_update_decay(rbtree
, y
->_right
);
926 assert(!is_decay(z
));
927 assert(!is_decay(z
->_left
));
929 set_parent(y
->_left
, y
, IS_LEFT
);
930 set_parent(y
->_right
, get_decay(get_parent(y
->_right
)), IS_RIGHT
);
931 assert(!is_decay(y
->_left
));
932 assert(!is_decay(y
->_right
));
935 int rcu_rbtree_remove(struct rcu_rbtree
*rbtree
,
936 struct rcu_rbtree_node
*z
)
938 struct rcu_rbtree_node
*x
, *y
;
939 unsigned int y_original_color
;
941 assert(!is_decay(rbtree
->root
));
942 dbg_printf("remove %p\n", z
->begin
);
945 assert(!is_decay(z
));
947 y_original_color
= y
->color
;
949 if (rcu_rbtree_is_nil(rbtree
, z
->_left
)) {
950 rcu_rbtree_transplant(rbtree
, z
, z
->_right
, 1);
951 assert(!is_decay(z
));
952 x
= get_decay(z
->_right
);
954 } else if (rcu_rbtree_is_nil(rbtree
, z
->_right
)) {
955 rcu_rbtree_transplant(rbtree
, z
, z
->_left
, 1);
956 assert(!is_decay(z
));
957 x
= get_decay(z
->_left
);
960 y
= rcu_rbtree_min(rbtree
, z
->_right
);
961 assert(!is_decay(y
));
962 y_original_color
= y
->color
;
964 rcu_rbtree_remove_nonil(rbtree
, z
, y
);
968 if (y_original_color
== COLOR_BLACK
)
969 rcu_rbtree_remove_fixup(rbtree
, x
);
972 * Commit all _CMM_STORE_SHARED().