1 /*
   2  * Copyright (c) 2001, 2017, 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((void*)_entries, NullEntry, _num_entries * SparsePRTEntry::size());
 124   memset((void*)_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 }
--- EOF ---