1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/g1/g1Arguments.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1ConcurrentRefine.hpp"
29 #include "gc/g1/heapRegion.hpp"
30 #include "gc/g1/heapRegionManager.inline.hpp"
31 #include "gc/g1/heapRegionSet.inline.hpp"
32 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
33 #include "logging/logStream.hpp"
34 #include "memory/allocation.hpp"
35 #include "utilities/bitMap.inline.hpp"
36
37 class MasterFreeRegionListChecker : public HeapRegionSetChecker {
38 public:
39 void check_mt_safety() {
40 // Master Free List MT safety protocol:
41 // (a) If we're at a safepoint, operations on the master free list
42 // should be invoked by either the VM thread (which will serialize
43 // them) or by the GC workers while holding the
44 // FreeList_lock.
45 // (b) If we're not at a safepoint, operations on the master free
46 // list should be invoked while holding the Heap_lock.
47
48 if (SafepointSynchronize::is_at_safepoint()) {
49 guarantee(Thread::current()->is_VM_thread() ||
50 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
51 } else {
52 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
53 }
54 }
55 bool is_correct_type(HeapRegion* hr) { return hr->is_free(); }
56 const char* get_description() { return "Free Regions"; }
57 };
58
59 HeapRegionManager::HeapRegionManager() :
60 _bot_mapper(NULL),
61 _cardtable_mapper(NULL),
62 _card_counts_mapper(NULL),
63 _available_map(mtGC),
64 _num_committed(0),
65 _allocated_heapregions_length(0),
66 _regions(), _heap_mapper(NULL),
67 _prev_bitmap_mapper(NULL),
68 _next_bitmap_mapper(NULL),
69 _free_list("Free list", new MasterFreeRegionListChecker())
70 { }
71
72 HeapRegionManager* HeapRegionManager::create_manager(G1CollectedHeap* heap) {
73 if (G1Arguments::is_heterogeneous_heap()) {
74 return new HeterogeneousHeapRegionManager((uint)(G1Arguments::heap_max_size_bytes() / HeapRegion::GrainBytes) /*heap size as num of regions*/);
75 }
76 return new HeapRegionManager();
77 }
78
79 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,
80 G1RegionToSpaceMapper* prev_bitmap,
81 G1RegionToSpaceMapper* next_bitmap,
82 G1RegionToSpaceMapper* bot,
83 G1RegionToSpaceMapper* cardtable,
84 G1RegionToSpaceMapper* card_counts) {
85 _allocated_heapregions_length = 0;
86
87 _heap_mapper = heap_storage;
88
89 _prev_bitmap_mapper = prev_bitmap;
90 _next_bitmap_mapper = next_bitmap;
91
92 _bot_mapper = bot;
93 _cardtable_mapper = cardtable;
94
95 _card_counts_mapper = card_counts;
96
97 MemRegion reserved = heap_storage->reserved();
98 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
99
100 _available_map.initialize(_regions.length());
101 }
102
103 bool HeapRegionManager::is_available(uint region) const {
104 return _available_map.at(region);
105 }
106
107 HeapRegion* HeapRegionManager::allocate_free_region(HeapRegionType type, uint requested_node_index) {
108 G1MemoryNodeManager* mgr = G1MemoryNodeManager::mgr();
109 HeapRegion* hr = NULL;
110 bool from_head = !type.is_young();
111
112 if (mgr->num_active_nodes() > 1) {
113 uint valid_node_index = mgr->valid_node_index(requested_node_index);
114 // Try to allocate with requested node index.
115 hr = _free_list.remove_region_with_node_index(from_head, valid_node_index, NULL);
116 }
117
118 if (hr == NULL) {
119 // If there's a single active node or we did not get a region from our requested node,
120 // try without requested node index.
121 hr = _free_list.remove_region(from_head);
122 }
123
124 if (hr != NULL) {
125 assert(hr->next() == NULL, "Single region should not have next");
126 assert(is_available(hr->hrm_index()), "Must be committed");
127 if (G1VerifyNUMAIdOfHeapRegions) {
128 // Read actual node index via system call.
129 uint actual_node_index = mgr->index_of_address(hr->bottom());
130 if (hr->node_index() != actual_node_index) {
131 log_debug(gc, heap, numa)("Heap Region (%u) has different node index. "
132 "actual index=%u, index=%u",
133 hr->hrm_index(), actual_node_index, hr->node_index());
134 }
135 }
136 }
137
138 return hr;
139 }
140
141 #ifdef ASSERT
142 bool HeapRegionManager::is_free(HeapRegion* hr) const {
143 return _free_list.contains(hr);
144 }
145 #endif
146
147 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
148 G1CollectedHeap* g1h = G1CollectedHeap::heap();
149 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
150 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
151 assert(reserved().contains(mr), "invariant");
152 return g1h->new_heap_region(hrm_index, mr);
153 }
154
155 void HeapRegionManager::commit_regions(uint index, size_t num_regions, uint node_index, WorkGang* pretouch_gang) {
156 guarantee(num_regions > 0, "Must commit more than zero regions");
157 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
158
159 _num_committed += (uint)num_regions;
160
161 _heap_mapper->commit_regions(index, num_regions, node_index, pretouch_gang);
162
163 // Also commit auxiliary data
164 _prev_bitmap_mapper->commit_regions(index, num_regions, node_index, pretouch_gang);
165 _next_bitmap_mapper->commit_regions(index, num_regions, node_index, pretouch_gang);
166
167 _bot_mapper->commit_regions(index, num_regions, node_index, pretouch_gang);
168 _cardtable_mapper->commit_regions(index, num_regions, node_index, pretouch_gang);
169
170 _card_counts_mapper->commit_regions(index, num_regions, node_index, pretouch_gang);
171 }
172
173 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
174 guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start);
175 guarantee(_num_committed >= num_regions, "pre-condition");
176
177 // Reset node index to distinguish with committed regions.
178 for (uint i = start; i < start + num_regions; i++) {
179 at(i)->set_node_index(G1MemoryNodeManager::InvalidNodeIndex);
180 }
181
182 // Print before uncommitting.
183 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
184 for (uint i = start; i < start + num_regions; i++) {
185 HeapRegion* hr = at(i);
186 G1CollectedHeap::heap()->hr_printer()->uncommit(hr);
187 }
188 }
189
190 _num_committed -= (uint)num_regions;
191
192 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
193 _heap_mapper->uncommit_regions(start, num_regions);
194
195 // Also uncommit auxiliary data
196 _prev_bitmap_mapper->uncommit_regions(start, num_regions);
197 _next_bitmap_mapper->uncommit_regions(start, num_regions);
198
199 _bot_mapper->uncommit_regions(start, num_regions);
200 _cardtable_mapper->uncommit_regions(start, num_regions);
201
202 _card_counts_mapper->uncommit_regions(start, num_regions);
203 }
204
205 static void print_numa_id_of_regions(uint start, uint num_regions) {
206 LogTarget(Debug, gc, heap, numa) lt;
207
208 if (lt.is_enabled()) {
209 LogStream ls(lt);
210
211 // Print header
212 // Below logs are checked by TestG1NUMATouchRegions.java.
213 ls.print_cr("Numa id of heap regions from %u to %u", start, start + num_regions - 1);
214 ls.print_cr("Heap Region# : numa id of pages");
215
216 for (uint i = start; i < start + num_regions; i++) {
217 ls.print_cr("%6u : %u", i, G1CollectedHeap::heap()->region_at(i)->node_index());
218 }
219 }
220 }
221
222 void HeapRegionManager::make_regions_available(uint start, uint num_regions, uint node_index, WorkGang* pretouch_gang) {
223 guarantee(num_regions > 0, "No point in calling this for zero regions");
224 commit_regions(start, num_regions, node_index, pretouch_gang);
225 for (uint i = start; i < start + num_regions; i++) {
226 if (_regions.get_by_index(i) == NULL) {
227 HeapRegion* new_hr = new_heap_region(i);
228 OrderAccess::storestore();
229 _regions.set_by_index(i, new_hr);
230 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
231 }
232 }
233
234 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
235
236 for (uint i = start; i < start + num_regions; i++) {
237 assert(is_available(i), "Just made region %u available but is apparently not.", i);
238 HeapRegion* hr = at(i);
239 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
240 G1CollectedHeap::heap()->hr_printer()->commit(hr);
241 }
242 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
243 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
244
245 hr->initialize(mr);
246 insert_into_free_list(at(i));
247 // Set node index of the heap region after initialization.
248 hr->set_node_index(G1MemoryNodeManager::mgr()->index_of_address(bottom));
249 }
250
251 if (G1PrintNUMAIdOfHeapRegions) {
252 print_numa_id_of_regions(start, num_regions);
253 }
254 }
255
256 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {
257 size_t used_sz =
258 _prev_bitmap_mapper->committed_size() +
259 _next_bitmap_mapper->committed_size() +
260 _bot_mapper->committed_size() +
261 _cardtable_mapper->committed_size() +
262 _card_counts_mapper->committed_size();
263
264 size_t committed_sz =
265 _prev_bitmap_mapper->reserved_size() +
266 _next_bitmap_mapper->reserved_size() +
267 _bot_mapper->reserved_size() +
268 _cardtable_mapper->reserved_size() +
269 _card_counts_mapper->reserved_size();
270
271 return MemoryUsage(0, used_sz, committed_sz, committed_sz);
272 }
273
274 uint HeapRegionManager::expand_by(uint num_regions, uint node_index, WorkGang* pretouch_workers) {
275 return expand_at(0, num_regions, node_index, pretouch_workers);
276 }
277
278 uint HeapRegionManager::expand_at(uint start, uint num_regions, uint node_index, WorkGang* pretouch_workers) {
279 if (num_regions == 0) {
280 return 0;
281 }
282
283 uint cur = start;
284 uint idx_last_found = 0;
285 uint num_last_found = 0;
286
287 uint expanded = 0;
288
289 while (expanded < num_regions &&
290 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
291 uint to_expand = MIN2(num_regions - expanded, num_last_found);
292 make_regions_available(idx_last_found, to_expand, node_index, pretouch_workers);
293 expanded += to_expand;
294 cur = idx_last_found + num_last_found + 1;
295 }
296
297 verify_optional();
298 return expanded;
299 }
300
301 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
302 uint found = 0;
303 size_t length_found = 0;
304 uint cur = 0;
305
306 while (length_found < num && cur < max_length()) {
307 HeapRegion* hr = _regions.get_by_index(cur);
308 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
309 // This region is a potential candidate for allocation into.
310 length_found++;
311 } else {
312 // This region is not a candidate. The next region is the next possible one.
313 found = cur + 1;
314 length_found = 0;
315 }
316 cur++;
317 }
318
319 if (length_found == num) {
320 for (uint i = found; i < (found + num); i++) {
321 HeapRegion* hr = _regions.get_by_index(i);
322 // sanity check
323 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
324 "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
325 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr));
326 }
327 return found;
328 } else {
329 return G1_NO_HRM_INDEX;
330 }
331 }
332
333 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
334 guarantee(r != NULL, "Start region must be a valid region");
335 guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index());
336 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
337 HeapRegion* hr = _regions.get_by_index(i);
338 if (is_available(i)) {
339 return hr;
340 }
341 }
342 return NULL;
343 }
344
345 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
346 uint len = max_length();
347
348 for (uint i = 0; i < len; i++) {
349 if (!is_available(i)) {
350 continue;
351 }
352 guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i);
353 bool res = blk->do_heap_region(at(i));
354 if (res) {
355 blk->set_incomplete();
356 return;
357 }
358 }
359 }
360
361 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
362 guarantee(res_idx != NULL, "checking");
363 guarantee(start_idx <= (max_length() + 1), "checking");
364
365 uint num_regions = 0;
366
367 uint cur = start_idx;
368 while (cur < max_length() && is_available(cur)) {
369 cur++;
370 }
371 if (cur == max_length()) {
372 return num_regions;
373 }
374 *res_idx = cur;
375 while (cur < max_length() && !is_available(cur)) {
376 cur++;
377 }
378 num_regions = cur - *res_idx;
379 #ifdef ASSERT
380 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
381 assert(!is_available(i), "just checking");
382 }
383 assert(cur == max_length() || num_regions == 0 || is_available(cur),
384 "The region at the current position %u must be available or at the end of the heap.", cur);
385 #endif
386 return num_regions;
387 }
388
389 uint HeapRegionManager::find_highest_free(bool* expanded) {
390 // Loop downwards from the highest region index, looking for an
391 // entry which is either free or not yet committed. If not yet
392 // committed, expand_at that index.
393 uint curr = max_length() - 1;
394 while (true) {
395 HeapRegion *hr = _regions.get_by_index(curr);
396 if (hr == NULL || !is_available(curr)) {
397 uint res = expand_at(curr, 1, G1MemoryNodeManager::AnyNodeIndex, NULL);
398 if (res == 1) {
399 *expanded = true;
400 return curr;
401 }
402 } else {
403 if (hr->is_free()) {
404 *expanded = false;
405 return curr;
406 }
407 }
408 if (curr == 0) {
409 return G1_NO_HRM_INDEX;
410 }
411 curr--;
412 }
413 }
414
415 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) {
416 size_t commits = 0;
417 uint start_index = (uint)_regions.get_index_by_address(range.start());
418 uint last_index = (uint)_regions.get_index_by_address(range.last());
419
420 // Ensure that each G1 region in the range is free, returning false if not.
421 // Commit those that are not yet available, and keep count.
422 for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {
423 if (!is_available(curr_index)) {
424 commits++;
425 expand_at(curr_index, 1, G1MemoryNodeManager::AnyNodeIndex, pretouch_workers);
426 }
427 HeapRegion* curr_region = _regions.get_by_index(curr_index);
428 if (!curr_region->is_free()) {
429 return false;
430 }
431 }
432
433 allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);
434 *commit_count = commits;
435 return true;
436 }
437
438 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const {
439 // Every worker will actually look at all regions, skipping over regions that
440 // are currently not committed.
441 // This also (potentially) iterates over regions newly allocated during GC. This
442 // is no problem except for some extra work.
443 const uint n_regions = hrclaimer->n_regions();
444 for (uint count = 0; count < n_regions; count++) {
445 const uint index = (start_index + count) % n_regions;
446 assert(index < n_regions, "sanity");
447 // Skip over unavailable regions
448 if (!is_available(index)) {
449 continue;
450 }
451 HeapRegion* r = _regions.get_by_index(index);
452 // We'll ignore regions already claimed.
453 // However, if the iteration is specified as concurrent, the values for
454 // is_starts_humongous and is_continues_humongous can not be trusted,
455 // and we should just blindly iterate over regions regardless of their
456 // humongous status.
457 if (hrclaimer->is_region_claimed(index)) {
458 continue;
459 }
460 // OK, try to claim it
461 if (!hrclaimer->claim_region(index)) {
462 continue;
463 }
464 bool res = blk->do_heap_region(r);
465 if (res) {
466 return;
467 }
468 }
469 }
470
471 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
472 assert(length() > 0, "the region sequence should not be empty");
473 assert(length() <= _allocated_heapregions_length, "invariant");
474 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
475 assert(num_regions_to_remove < length(), "We should never remove all regions");
476
477 if (num_regions_to_remove == 0) {
478 return 0;
479 }
480
481 uint removed = 0;
482 uint cur = _allocated_heapregions_length - 1;
483 uint idx_last_found = 0;
484 uint num_last_found = 0;
485
486 while ((removed < num_regions_to_remove) &&
487 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
488 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
489
490 shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
491
492 cur = idx_last_found;
493 removed += to_remove;
494 }
495
496 verify_optional();
497
498 return removed;
499 }
500
501 void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
502 #ifdef ASSERT
503 for (uint i = index; i < (index + num_regions); i++) {
504 assert(is_available(i), "Expected available region at index %u", i);
505 assert(at(i)->is_empty(), "Expected empty region at index %u", i);
506 assert(at(i)->is_free(), "Expected free region at index %u", i);
507 }
508 #endif
509 uncommit_regions(index, num_regions);
510 }
511
512 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
513 guarantee(start_idx < _allocated_heapregions_length, "checking");
514 guarantee(res_idx != NULL, "checking");
515
516 uint num_regions_found = 0;
517
518 jlong cur = start_idx;
519 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
520 cur--;
521 }
522 if (cur == -1) {
523 return num_regions_found;
524 }
525 jlong old_cur = cur;
526 // cur indexes the first empty region
527 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
528 cur--;
529 }
530 *res_idx = cur + 1;
531 num_regions_found = old_cur - cur;
532
533 #ifdef ASSERT
534 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
535 assert(at(i)->is_empty(), "just checking");
536 }
537 #endif
538 return num_regions_found;
539 }
540
541 void HeapRegionManager::verify() {
542 guarantee(length() <= _allocated_heapregions_length,
543 "invariant: _length: %u _allocated_length: %u",
544 length(), _allocated_heapregions_length);
545 guarantee(_allocated_heapregions_length <= max_length(),
546 "invariant: _allocated_length: %u _max_length: %u",
547 _allocated_heapregions_length, max_length());
548
549 bool prev_committed = true;
550 uint num_committed = 0;
551 HeapWord* prev_end = heap_bottom();
552 for (uint i = 0; i < _allocated_heapregions_length; i++) {
553 if (!is_available(i)) {
554 prev_committed = false;
555 continue;
556 }
557 num_committed++;
558 HeapRegion* hr = _regions.get_by_index(i);
559 guarantee(hr != NULL, "invariant: i: %u", i);
560 guarantee(!prev_committed || hr->bottom() == prev_end,
561 "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT,
562 i, HR_FORMAT_PARAMS(hr), p2i(prev_end));
563 guarantee(hr->hrm_index() == i,
564 "invariant: i: %u hrm_index(): %u", i, hr->hrm_index());
565 // Asserts will fire if i is >= _length
566 HeapWord* addr = hr->bottom();
567 guarantee(addr_to_region(addr) == hr, "sanity");
568 // We cannot check whether the region is part of a particular set: at the time
569 // this method may be called, we have only completed allocation of the regions,
570 // but not put into a region set.
571 prev_committed = true;
572 prev_end = hr->end();
573 }
574 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
575 guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i);
576 }
577
578 guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed);
579 _free_list.verify();
580 }
581
582 #ifndef PRODUCT
583 void HeapRegionManager::verify_optional() {
584 verify();
585 }
586 #endif // PRODUCT
587
588 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
589 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm->_allocated_heapregions_length), _claims(NULL) {
590 assert(n_workers > 0, "Need at least one worker.");
591 uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
592 memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions);
593 _claims = new_claims;
594 }
595
596 HeapRegionClaimer::~HeapRegionClaimer() {
597 FREE_C_HEAP_ARRAY(uint, _claims);
598 }
599
600 uint HeapRegionClaimer::offset_for_worker(uint worker_id) const {
601 assert(worker_id < _n_workers, "Invalid worker_id.");
602 return _n_regions * worker_id / _n_workers;
603 }
604
605 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
606 assert(region_index < _n_regions, "Invalid index.");
607 return _claims[region_index] == Claimed;
608 }
609
610 bool HeapRegionClaimer::claim_region(uint region_index) {
611 assert(region_index < _n_regions, "Invalid index.");
612 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
613 return old_val == Unclaimed;
614 }