1 /*
2 * Copyright (c) 2001, 2016, 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/heapRegion.hpp"
27 #include "gc/g1/heapRegionBounds.inline.hpp"
28 #include "gc/g1/heapRegionRemSet.hpp"
29 #include "gc/g1/sparsePRT.hpp"
30 #include "gc/shared/cardTableModRefBS.hpp"
31 #include "gc/shared/space.inline.hpp"
32 #include "memory/allocation.inline.hpp"
33 #include "runtime/atomic.hpp"
34 #include "runtime/mutexLocker.hpp"
35
36 // Check that the size of the SparsePRTEntry is evenly divisible by the maximum
37 // member type to avoid SIGBUS when accessing them.
38 STATIC_ASSERT(sizeof(SparsePRTEntry) % sizeof(int) == 0);
39
40 void SparsePRTEntry::init(RegionIdx_t region_ind) {
41 // Check that the card array element type can represent all cards in the region.
42 // Choose a large SparsePRTEntry::card_elem_t (e.g. CardIdx_t) if required.
43 assert(((size_t)1 << (sizeof(SparsePRTEntry::card_elem_t) * BitsPerByte)) *
44 G1SATBCardTableModRefBS::card_size >= HeapRegionBounds::max_size(), "precondition");
45 assert(G1RSetSparseRegionEntries > 0, "precondition");
46 _region_ind = region_ind;
47 _next_index = RSHashTable::NullEntry;
48 _next_null = 0;
49 }
50
51 bool SparsePRTEntry::contains_card(CardIdx_t card_index) const {
52 for (int i = 0; i < num_valid_cards(); i++) {
53 if (card(i) == card_index) {
54 return true;
55 }
56 }
57 return false;
58 }
59
60 SparsePRTEntry::AddCardResult SparsePRTEntry::add_card(CardIdx_t card_index) {
61 for (int i = 0; i < num_valid_cards(); i++) {
62 if (card(i) == card_index) {
63 return found;
64 }
65 }
66 if (num_valid_cards() < cards_num() - 1) {
67 _cards[_next_null] = (card_elem_t)card_index;
68 _next_null++;
69 return added;
70 }
71 // Otherwise, we're full.
72 return overflow;
73 }
74
75 void SparsePRTEntry::copy_cards(card_elem_t* cards) const {
76 memcpy(cards, _cards, cards_num() * sizeof(card_elem_t));
77 }
78
79 void SparsePRTEntry::copy_cards(SparsePRTEntry* e) const {
80 copy_cards(e->_cards);
81 assert(_next_null >= 0, "invariant");
82 assert(_next_null <= cards_num(), "invariant");
83 e->_next_null = _next_null;
84 }
85
86 // ----------------------------------------------------------------------
87
88 float RSHashTable::TableOccupancyFactor = 0.5f;
89
90 RSHashTable::RSHashTable(size_t capacity) :
91 _capacity(capacity), _capacity_mask(capacity-1),
92 _occupied_entries(0), _occupied_cards(0),
93 _entries(NULL),
94 _buckets(NEW_C_HEAP_ARRAY(int, capacity, mtGC)),
95 _free_list(NullEntry), _free_region(0)
96 {
97 _num_entries = (capacity * TableOccupancyFactor) + 1;
98 _entries = (SparsePRTEntry*)NEW_C_HEAP_ARRAY(char, _num_entries * SparsePRTEntry::size(), mtGC);
99 clear();
100 }
101
102 RSHashTable::~RSHashTable() {
103 if (_entries != NULL) {
104 FREE_C_HEAP_ARRAY(SparsePRTEntry, _entries);
105 _entries = NULL;
106 }
107 if (_buckets != NULL) {
108 FREE_C_HEAP_ARRAY(int, _buckets);
109 _buckets = NULL;
110 }
111 }
112
113 void RSHashTable::clear() {
114 _occupied_entries = 0;
115 _occupied_cards = 0;
116 guarantee(_entries != NULL, "INV");
117 guarantee(_buckets != NULL, "INV");
118
119 guarantee(_capacity <= ((size_t)1 << (sizeof(int)*BitsPerByte-1)) - 1,
120 "_capacity too large");
121
122 // This will put -1 == NullEntry in the key field of all entries.
123 memset(_entries, NullEntry, _num_entries * SparsePRTEntry::size());
124 memset(_buckets, NullEntry, _capacity * sizeof(int));
125 _free_list = NullEntry;
126 _free_region = 0;
127 }
128
129 bool RSHashTable::add_card(RegionIdx_t region_ind, CardIdx_t card_index) {
130 SparsePRTEntry* e = entry_for_region_ind_create(region_ind);
131 assert(e != NULL && e->r_ind() == region_ind,
132 "Postcondition of call above.");
133 SparsePRTEntry::AddCardResult res = e->add_card(card_index);
134 if (res == SparsePRTEntry::added) _occupied_cards++;
135 assert(e->num_valid_cards() > 0, "Postcondition");
136 return res != SparsePRTEntry::overflow;
137 }
138
139 SparsePRTEntry* RSHashTable::get_entry(RegionIdx_t region_ind) const {
140 int ind = (int) (region_ind & capacity_mask());
141 int cur_ind = _buckets[ind];
142 SparsePRTEntry* cur;
143 while (cur_ind != NullEntry &&
144 (cur = entry(cur_ind))->r_ind() != region_ind) {
145 cur_ind = cur->next_index();
146 }
147
148 if (cur_ind == NullEntry) return NULL;
149 // Otherwise...
150 assert(cur->r_ind() == region_ind, "Postcondition of loop + test above.");
151 assert(cur->num_valid_cards() > 0, "Inv");
152 return cur;
153 }
154
155 bool RSHashTable::delete_entry(RegionIdx_t region_ind) {
156 int ind = (int) (region_ind & capacity_mask());
157 int* prev_loc = &_buckets[ind];
158 int cur_ind = *prev_loc;
159 SparsePRTEntry* cur;
160 while (cur_ind != NullEntry &&
161 (cur = entry(cur_ind))->r_ind() != region_ind) {
162 prev_loc = cur->next_index_addr();
163 cur_ind = *prev_loc;
164 }
165
166 if (cur_ind == NullEntry) return false;
167 // Otherwise, splice out "cur".
168 *prev_loc = cur->next_index();
169 _occupied_cards -= cur->num_valid_cards();
170 free_entry(cur_ind);
171 _occupied_entries--;
172 return true;
173 }
174
175 SparsePRTEntry*
176 RSHashTable::entry_for_region_ind_create(RegionIdx_t region_ind) {
177 SparsePRTEntry* res = get_entry(region_ind);
178 if (res == NULL) {
179 int new_ind = alloc_entry();
180 res = entry(new_ind);
181 res->init(region_ind);
182 // Insert at front.
183 int ind = (int) (region_ind & capacity_mask());
184 res->set_next_index(_buckets[ind]);
185 _buckets[ind] = new_ind;
186 _occupied_entries++;
187 }
188 return res;
189 }
190
191 int RSHashTable::alloc_entry() {
192 int res;
193 if (_free_list != NullEntry) {
194 res = _free_list;
195 _free_list = entry(res)->next_index();
196 return res;
197 } else if ((size_t)_free_region < _num_entries) {
198 res = _free_region;
199 _free_region++;
200 return res;
201 } else {
202 return NullEntry;
203 }
204 }
205
206 void RSHashTable::free_entry(int fi) {
207 entry(fi)->set_next_index(_free_list);
208 _free_list = fi;
209 }
210
211 void RSHashTable::add_entry(SparsePRTEntry* e) {
212 assert(e->num_valid_cards() > 0, "Precondition.");
213 SparsePRTEntry* e2 = entry_for_region_ind_create(e->r_ind());
214 e->copy_cards(e2);
215 _occupied_cards += e2->num_valid_cards();
216 assert(e2->num_valid_cards() > 0, "Postcondition.");
217 }
218
219 CardIdx_t RSHashTableIter::find_first_card_in_list() {
220 while (_bl_ind != RSHashTable::NullEntry) {
221 SparsePRTEntry* sparse_entry = _rsht->entry(_bl_ind);
222 if (sparse_entry->num_valid_cards() > 0) {
223 return sparse_entry->card(0);
224 } else {
225 _bl_ind = sparse_entry->next_index();
226 }
227 }
228 // Otherwise, none found:
229 return NoCardFound;
230 }
231
232 size_t RSHashTableIter::compute_card_ind(CardIdx_t ci) {
233 return (_rsht->entry(_bl_ind)->r_ind() * HeapRegion::CardsPerRegion) + ci;
234 }
235
236 bool RSHashTableIter::has_next(size_t& card_index) {
237 _card_ind++;
238 if (_bl_ind >= 0) {
239 SparsePRTEntry* e = _rsht->entry(_bl_ind);
240 if (_card_ind < e->num_valid_cards()) {
241 CardIdx_t ci = e->card(_card_ind);
242 card_index = compute_card_ind(ci);
243 return true;
244 }
245 }
246
247 // Otherwise, must find the next valid entry.
248 _card_ind = 0;
249
250 if (_bl_ind != RSHashTable::NullEntry) {
251 _bl_ind = _rsht->entry(_bl_ind)->next_index();
252 CardIdx_t ci = find_first_card_in_list();
253 if (ci != NoCardFound) {
254 card_index = compute_card_ind(ci);
255 return true;
256 }
257 }
258 // If we didn't return above, must go to the next non-null table index.
259 _tbl_ind++;
260 while ((size_t)_tbl_ind < _rsht->capacity()) {
261 _bl_ind = _rsht->_buckets[_tbl_ind];
262 CardIdx_t ci = find_first_card_in_list();
263 if (ci != NoCardFound) {
264 card_index = compute_card_ind(ci);
265 return true;
266 }
267 // Otherwise, try next entry.
268 _tbl_ind++;
269 }
270 // Otherwise, there were no entry.
271 return false;
272 }
273
274 bool RSHashTable::contains_card(RegionIdx_t region_index, CardIdx_t card_index) const {
275 SparsePRTEntry* e = get_entry(region_index);
276 return (e != NULL && e->contains_card(card_index));
277 }
278
279 size_t RSHashTable::mem_size() const {
280 return sizeof(RSHashTable) +
281 _num_entries * (SparsePRTEntry::size() + sizeof(int));
282 }
283
284 // ----------------------------------------------------------------------
285
286 SparsePRT* volatile SparsePRT::_head_expanded_list = NULL;
287
288 void SparsePRT::add_to_expanded_list(SparsePRT* sprt) {
289 // We could expand multiple times in a pause -- only put on list once.
290 if (sprt->expanded()) return;
291 sprt->set_expanded(true);
292 SparsePRT* hd = _head_expanded_list;
293 while (true) {
294 sprt->_next_expanded = hd;
295 SparsePRT* res =
296 (SparsePRT*)
297 Atomic::cmpxchg_ptr(sprt, &_head_expanded_list, hd);
298 if (res == hd) return;
299 else hd = res;
300 }
301 }
302
303
304 SparsePRT* SparsePRT::get_from_expanded_list() {
305 SparsePRT* hd = _head_expanded_list;
306 while (hd != NULL) {
307 SparsePRT* next = hd->next_expanded();
308 SparsePRT* res =
309 (SparsePRT*)
310 Atomic::cmpxchg_ptr(next, &_head_expanded_list, hd);
311 if (res == hd) {
312 hd->set_next_expanded(NULL);
313 return hd;
314 } else {
315 hd = res;
316 }
317 }
318 return NULL;
319 }
320
321 void SparsePRT::reset_for_cleanup_tasks() {
322 _head_expanded_list = NULL;
323 }
324
325 void SparsePRT::do_cleanup_work(SparsePRTCleanupTask* sprt_cleanup_task) {
326 if (should_be_on_expanded_list()) {
327 sprt_cleanup_task->add(this);
328 }
329 }
330
331 void SparsePRT::finish_cleanup_task(SparsePRTCleanupTask* sprt_cleanup_task) {
332 assert(ParGCRareEvent_lock->owned_by_self(), "pre-condition");
333 SparsePRT* head = sprt_cleanup_task->head();
334 SparsePRT* tail = sprt_cleanup_task->tail();
335 if (head != NULL) {
336 assert(tail != NULL, "if head is not NULL, so should tail");
337
338 tail->set_next_expanded(_head_expanded_list);
339 _head_expanded_list = head;
340 } else {
341 assert(tail == NULL, "if head is NULL, so should tail");
342 }
343 }
344
345 bool SparsePRT::should_be_on_expanded_list() {
346 if (_expanded) {
347 assert(_cur != _next, "if _expanded is true, cur should be != _next");
348 } else {
349 assert(_cur == _next, "if _expanded is false, cur should be == _next");
350 }
351 return expanded();
352 }
353
354 void SparsePRT::cleanup_all() {
355 // First clean up all expanded tables so they agree on next and cur.
356 SparsePRT* sprt = get_from_expanded_list();
357 while (sprt != NULL) {
358 sprt->cleanup();
359 sprt = get_from_expanded_list();
360 }
361 }
362
363
364 SparsePRT::SparsePRT(HeapRegion* hr) :
365 _hr(hr), _expanded(false), _next_expanded(NULL)
366 {
367 _cur = new RSHashTable(InitialCapacity);
368 _next = _cur;
369 }
370
371
372 SparsePRT::~SparsePRT() {
373 assert(_next != NULL && _cur != NULL, "Inv");
374 if (_cur != _next) { delete _cur; }
375 delete _next;
376 }
377
378
379 size_t SparsePRT::mem_size() const {
380 // We ignore "_cur" here, because it either = _next, or else it is
381 // on the deleted list.
382 return sizeof(SparsePRT) + _next->mem_size();
383 }
384
385 bool SparsePRT::add_card(RegionIdx_t region_id, CardIdx_t card_index) {
386 if (_next->should_expand()) {
387 expand();
388 }
389 return _next->add_card(region_id, card_index);
390 }
391
392 SparsePRTEntry* SparsePRT::get_entry(RegionIdx_t region_id) {
393 return _next->get_entry(region_id);
394 }
395
396 bool SparsePRT::delete_entry(RegionIdx_t region_id) {
397 return _next->delete_entry(region_id);
398 }
399
400 void SparsePRT::clear() {
401 // If they differ, _next is bigger then cur, so next has no chance of
402 // being the initial size.
403 if (_next != _cur) {
404 delete _next;
405 }
406
407 if (_cur->capacity() != InitialCapacity) {
408 delete _cur;
409 _cur = new RSHashTable(InitialCapacity);
410 } else {
411 _cur->clear();
412 }
413 _next = _cur;
414 _expanded = false;
415 }
416
417 void SparsePRT::cleanup() {
418 // Make sure that the current and next tables agree.
419 if (_cur != _next) {
420 delete _cur;
421 }
422 _cur = _next;
423 set_expanded(false);
424 }
425
426 void SparsePRT::expand() {
427 RSHashTable* last = _next;
428 _next = new RSHashTable(last->capacity() * 2);
429 for (size_t i = 0; i < last->num_entries(); i++) {
430 SparsePRTEntry* e = last->entry((int)i);
431 if (e->valid_entry()) {
432 _next->add_entry(e);
433 }
434 }
435 if (last != _cur) {
436 delete last;
437 }
438 add_to_expanded_list(this);
439 }
440
441 void SparsePRTCleanupTask::add(SparsePRT* sprt) {
442 assert(sprt->should_be_on_expanded_list(), "pre-condition");
443
444 sprt->set_next_expanded(NULL);
445 if (_tail != NULL) {
446 _tail->set_next_expanded(sprt);
447 } else {
448 _head = sprt;
449 }
450 _tail = sprt;
451 }