1 /*
   2  * Copyright (c) 2011, 2014, 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_implementation/g1/g1CollectedHeap.inline.hpp"
  27 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  28 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
  29 
  30 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  31 
  32 uint FreeRegionList::_unrealistically_long_length = 0;
  33 
  34 void HeapRegionSetBase::fill_in_ext_msg(hrs_ext_msg* msg, const char* message) {
  35   msg->append("[%s] %s ln: %u cy: "SIZE_FORMAT,
  36               name(), message, length(), total_capacity_bytes());
  37   fill_in_ext_msg_extra(msg);
  38 }
  39 
  40 #ifndef PRODUCT
  41 void HeapRegionSetBase::verify_region(HeapRegion* hr) {
  42   assert(hr->containing_set() == this, err_msg("Inconsistent containing set for %u", hr->hrm_index()));
  43   assert(!hr->is_young(), err_msg("Adding young region %u", hr->hrm_index())); // currently we don't use these sets for young regions
  44   assert(hr->is_humongous() == regions_humongous(), err_msg("Wrong humongous state for region %u and set %s", hr->hrm_index(), name()));
  45   assert(hr->is_free() == regions_free(), err_msg("Wrong free state for region %u and set %s", hr->hrm_index(), name()));
  46   assert(!hr->is_free() || hr->is_empty(), err_msg("Free region %u is not empty for set %s", hr->hrm_index(), name()));
  47   assert(!hr->is_empty() || hr->is_free(), err_msg("Empty region %u is not free for set %s", hr->hrm_index(), name()));
  48   assert(hr->rem_set()->verify_ready_for_par_iteration(), err_msg("Wrong iteration state %u", hr->hrm_index()));
  49 }
  50 #endif
  51 
  52 void HeapRegionSetBase::verify() {
  53   // It's important that we also observe the MT safety protocol even
  54   // for the verification calls. If we do verification without the
  55   // appropriate locks and the set changes underneath our feet
  56   // verification might fail and send us on a wild goose chase.
  57   check_mt_safety();
  58 
  59   guarantee(( is_empty() && length() == 0 && total_capacity_bytes() == 0) ||
  60             (!is_empty()),
  61             hrs_ext_msg(this, "invariant"));
  62 }
  63 
  64 void HeapRegionSetBase::verify_start() {
  65   // See comment in verify() about MT safety and verification.
  66   check_mt_safety();
  67   assert(!_verify_in_progress,
  68          hrs_ext_msg(this, "verification should not be in progress"));
  69 
  70   // Do the basic verification first before we do the checks over the regions.
  71   HeapRegionSetBase::verify();
  72 
  73   _verify_in_progress = true;
  74 }
  75 
  76 void HeapRegionSetBase::verify_end() {
  77   // See comment in verify() about MT safety and verification.
  78   check_mt_safety();
  79   assert(_verify_in_progress,
  80          hrs_ext_msg(this, "verification should be in progress"));
  81 
  82   _verify_in_progress = false;
  83 }
  84 
  85 void HeapRegionSetBase::print_on(outputStream* out, bool print_contents) {
  86   out->cr();
  87   out->print_cr("Set: %s ("PTR_FORMAT")", name(), this);
  88   out->print_cr("  Region Assumptions");
  89   out->print_cr("    humongous         : %s", BOOL_TO_STR(regions_humongous()));
  90   out->print_cr("    free              : %s", BOOL_TO_STR(regions_free()));
  91   out->print_cr("  Attributes");
  92   out->print_cr("    length            : %14u", length());
  93   out->print_cr("    total capacity    : "SIZE_FORMAT_W(14)" bytes",
  94                 total_capacity_bytes());
  95 }
  96 
  97 HeapRegionSetBase::HeapRegionSetBase(const char* name, bool humongous, bool free, HRSMtSafeChecker* mt_safety_checker)
  98   : _name(name), _verify_in_progress(false),
  99     _is_humongous(humongous), _is_free(free), _mt_safety_checker(mt_safety_checker),
 100     _count()
 101 { }
 102 
 103 void FreeRegionList::set_unrealistically_long_length(uint len) {
 104   guarantee(_unrealistically_long_length == 0, "should only be set once");
 105   _unrealistically_long_length = len;
 106 }
 107 
 108 void FreeRegionList::fill_in_ext_msg_extra(hrs_ext_msg* msg) {
 109   msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, _head, _tail);
 110 }
 111 
 112 void FreeRegionList::remove_all() {
 113   check_mt_safety();
 114   verify_optional();
 115 
 116   HeapRegion* curr = _head;
 117   while (curr != NULL) {
 118     verify_region(curr);
 119 
 120     HeapRegion* next = curr->next();
 121     curr->set_next(NULL);
 122     curr->set_prev(NULL);
 123     curr->set_containing_set(NULL);
 124     curr = next;
 125   }
 126   clear();
 127 
 128   verify_optional();
 129 }
 130 
 131 void FreeRegionList::add_ordered(FreeRegionList* from_list) {
 132   check_mt_safety();
 133   from_list->check_mt_safety();
 134 
 135   verify_optional();
 136   from_list->verify_optional();
 137 
 138   if (from_list->is_empty()) {
 139     return;
 140   }
 141 
 142   #ifdef ASSERT
 143   FreeRegionListIterator iter(from_list);
 144   while (iter.more_available()) {
 145     HeapRegion* hr = iter.get_next();
 146     // In set_containing_set() we check that we either set the value
 147     // from NULL to non-NULL or vice versa to catch bugs. So, we have
 148     // to NULL it first before setting it to the value.
 149     hr->set_containing_set(NULL);
 150     hr->set_containing_set(this);
 151   }
 152   #endif // ASSERT
 153 
 154   if (is_empty()) {
 155     assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));
 156     _head = from_list->_head;
 157     _tail = from_list->_tail;
 158   } else {
 159     HeapRegion* curr_to = _head;
 160     HeapRegion* curr_from = from_list->_head;
 161 
 162     while (curr_from != NULL) {
 163       while (curr_to != NULL && curr_to->hrm_index() < curr_from->hrm_index()) {
 164         curr_to = curr_to->next();
 165       }
 166 
 167       if (curr_to == NULL) {
 168         // The rest of the from list should be added as tail
 169         _tail->set_next(curr_from);
 170         curr_from->set_prev(_tail);
 171         curr_from = NULL;
 172       } else {
 173         HeapRegion* next_from = curr_from->next();
 174 
 175         curr_from->set_next(curr_to);
 176         curr_from->set_prev(curr_to->prev());
 177         if (curr_to->prev() == NULL) {
 178           _head = curr_from;
 179         } else {
 180           curr_to->prev()->set_next(curr_from);
 181         }
 182         curr_to->set_prev(curr_from);
 183 
 184         curr_from = next_from;
 185       }
 186     }
 187 
 188     if (_tail->hrm_index() < from_list->_tail->hrm_index()) {
 189       _tail = from_list->_tail;
 190     }
 191   }
 192 
 193   _count.increment(from_list->length(), from_list->total_capacity_bytes());
 194   from_list->clear();
 195 
 196   verify_optional();
 197   from_list->verify_optional();
 198 }
 199 
 200 void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) {
 201   check_mt_safety();
 202   assert(num_regions >= 1, hrs_ext_msg(this, "pre-condition"));
 203   assert(!is_empty(), hrs_ext_msg(this, "pre-condition"));
 204 
 205   verify_optional();
 206   DEBUG_ONLY(uint old_length = length();)
 207 
 208   HeapRegion* curr = first;
 209   uint count = 0;
 210   while (count < num_regions) {
 211     verify_region(curr);
 212     HeapRegion* next = curr->next();
 213     HeapRegion* prev = curr->prev();
 214 
 215     assert(count < num_regions,
 216            hrs_err_msg("[%s] should not come across more regions "
 217                        "pending for removal than num_regions: %u",
 218                        name(), num_regions));
 219 
 220     if (prev == NULL) {
 221       assert(_head == curr, hrs_ext_msg(this, "invariant"));
 222       _head = next;
 223     } else {
 224       assert(_head != curr, hrs_ext_msg(this, "invariant"));
 225       prev->set_next(next);
 226     }
 227     if (next == NULL) {
 228       assert(_tail == curr, hrs_ext_msg(this, "invariant"));
 229       _tail = prev;
 230     } else {
 231       assert(_tail != curr, hrs_ext_msg(this, "invariant"));
 232       next->set_prev(prev);
 233     }
 234     if (_last = curr) {
 235       _last = NULL;
 236     }
 237 
 238     curr->set_next(NULL);
 239     curr->set_prev(NULL);
 240     remove(curr);
 241 
 242     count++;
 243     curr = next;
 244   }
 245 
 246   assert(count == num_regions,
 247          hrs_err_msg("[%s] count: %u should be == num_regions: %u",
 248                      name(), count, num_regions));
 249   assert(length() + num_regions == old_length,
 250          hrs_err_msg("[%s] new length should be consistent "
 251                      "new length: %u old length: %u num_regions: %u",
 252                      name(), length(), old_length, num_regions));
 253 
 254   verify_optional();
 255 }
 256 
 257 void FreeRegionList::verify() {
 258   // See comment in HeapRegionSetBase::verify() about MT safety and
 259   // verification.
 260   check_mt_safety();
 261 
 262   // This will also do the basic verification too.
 263   verify_start();
 264 
 265   verify_list();
 266 
 267   verify_end();
 268 }
 269 
 270 void FreeRegionList::clear() {
 271   _count = HeapRegionSetCount();
 272   _head = NULL;
 273   _tail = NULL;
 274   _last = NULL;
 275 }
 276 
 277 void FreeRegionList::print_on(outputStream* out, bool print_contents) {
 278   HeapRegionSetBase::print_on(out, print_contents);
 279   out->print_cr("  Linking");
 280   out->print_cr("    head              : "PTR_FORMAT, _head);
 281   out->print_cr("    tail              : "PTR_FORMAT, _tail);
 282 
 283   if (print_contents) {
 284     out->print_cr("  Contents");
 285     FreeRegionListIterator iter(this);
 286     while (iter.more_available()) {
 287       HeapRegion* hr = iter.get_next();
 288       hr->print_on(out);
 289     }
 290   }
 291 
 292   out->cr();
 293 }
 294 
 295 void FreeRegionList::verify_list() {
 296   HeapRegion* curr = _head;
 297   HeapRegion* prev1 = NULL;
 298   HeapRegion* prev0 = NULL;
 299   uint count = 0;
 300   size_t capacity = 0;
 301   uint last_index = 0;
 302 
 303   guarantee(_head == NULL || _head->prev() == NULL, "_head should not have a prev");
 304   while (curr != NULL) {
 305     verify_region(curr);
 306 
 307     count++;
 308     guarantee(count < _unrealistically_long_length,
 309         hrs_err_msg("[%s] the calculated length: %u seems very long, is there maybe a cycle? curr: "PTR_FORMAT" prev0: "PTR_FORMAT" " "prev1: "PTR_FORMAT" length: %u", name(), count, curr, prev0, prev1, length()));
 310 
 311     if (curr->next() != NULL) {
 312       guarantee(curr->next()->prev() == curr, "Next or prev pointers messed up");
 313     }
 314     guarantee(curr->hrm_index() == 0 || curr->hrm_index() > last_index, "List should be sorted");
 315     last_index = curr->hrm_index();
 316 
 317     capacity += curr->capacity();
 318 
 319     prev1 = prev0;
 320     prev0 = curr;
 321     curr = curr->next();
 322   }
 323 
 324   guarantee(_tail == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), _tail->hrm_index(), prev0->hrm_index()));
 325   guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next");
 326   guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count));
 327   guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
 328       name(), total_capacity_bytes(), capacity));
 329 }
 330 
 331 // Note on the check_mt_safety() methods below:
 332 //
 333 // Verification of the "master" heap region sets / lists that are
 334 // maintained by G1CollectedHeap is always done during a STW pause and
 335 // by the VM thread at the start / end of the pause. The standard
 336 // verification methods all assert check_mt_safety(). This is
 337 // important as it ensures that verification is done without
 338 // concurrent updates taking place at the same time. It follows, that,
 339 // for the "master" heap region sets / lists, the check_mt_safety()
 340 // method should include the VM thread / STW case.
 341 
 342 void MasterFreeRegionListMtSafeChecker::check() {
 343   // Master Free List MT safety protocol:
 344   // (a) If we're at a safepoint, operations on the master free list
 345   // should be invoked by either the VM thread (which will serialize
 346   // them) or by the GC workers while holding the
 347   // FreeList_lock.
 348   // (b) If we're not at a safepoint, operations on the master free
 349   // list should be invoked while holding the Heap_lock.
 350 
 351   if (SafepointSynchronize::is_at_safepoint()) {
 352     guarantee(Thread::current()->is_VM_thread() ||
 353               FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
 354   } else {
 355     guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
 356   }
 357 }
 358 
 359 void SecondaryFreeRegionListMtSafeChecker::check() {
 360   // Secondary Free List MT safety protocol:
 361   // Operations on the secondary free list should always be invoked
 362   // while holding the SecondaryFreeList_lock.
 363 
 364   guarantee(SecondaryFreeList_lock->owned_by_self(), "secondary free list MT safety protocol");
 365 }
 366 
 367 void OldRegionSetMtSafeChecker::check() {
 368   // Master Old Set MT safety protocol:
 369   // (a) If we're at a safepoint, operations on the master old set
 370   // should be invoked:
 371   // - by the VM thread (which will serialize them), or
 372   // - by the GC workers while holding the FreeList_lock, if we're
 373   //   at a safepoint for an evacuation pause (this lock is taken
 374   //   anyway when an GC alloc region is retired so that a new one
 375   //   is allocated from the free list), or
 376   // - by the GC workers while holding the OldSets_lock, if we're at a
 377   //   safepoint for a cleanup pause.
 378   // (b) If we're not at a safepoint, operations on the master old set
 379   // should be invoked while holding the Heap_lock.
 380 
 381   if (SafepointSynchronize::is_at_safepoint()) {
 382     guarantee(Thread::current()->is_VM_thread()
 383         || FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
 384         "master old set MT safety protocol at a safepoint");
 385   } else {
 386     guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
 387   }
 388 }
 389 
 390 void HumongousRegionSetMtSafeChecker::check() {
 391   // Humongous Set MT safety protocol:
 392   // (a) If we're at a safepoint, operations on the master humongous
 393   // set should be invoked by either the VM thread (which will
 394   // serialize them) or by the GC workers while holding the
 395   // OldSets_lock.
 396   // (b) If we're not at a safepoint, operations on the master
 397   // humongous set should be invoked while holding the Heap_lock.
 398 
 399   if (SafepointSynchronize::is_at_safepoint()) {
 400     guarantee(Thread::current()->is_VM_thread() ||
 401               OldSets_lock->owned_by_self(),
 402               "master humongous set MT safety protocol at a safepoint");
 403   } else {
 404     guarantee(Heap_lock->owned_by_self(),
 405               "master humongous set MT safety protocol outside a safepoint");
 406   }
 407 }
 408 
 409 void FreeRegionList_test() {
 410   FreeRegionList l("test");
 411 
 412   const uint num_regions_in_test = 5;
 413   // Create a fake heap. It does not need to be valid, as the HeapRegion constructor
 414   // does not access it.
 415   MemRegion heap(NULL, num_regions_in_test * HeapRegion::GrainWords);
 416   // Allocate a fake BOT because the HeapRegion constructor initializes
 417   // the BOT.
 418   size_t bot_size = G1BlockOffsetSharedArray::compute_size(heap.word_size());
 419   HeapWord* bot_data = NEW_C_HEAP_ARRAY(HeapWord, bot_size, mtGC);
 420   ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(heap.word_size()));
 421   G1RegionToSpaceMapper* bot_storage =
 422     G1RegionToSpaceMapper::create_mapper(bot_rs,
 423                                          os::vm_page_size(),
 424                                          HeapRegion::GrainBytes,
 425                                          G1BlockOffsetSharedArray::N_bytes,
 426                                          mtGC);
 427   G1BlockOffsetSharedArray oa(heap, bot_storage);
 428   bot_storage->commit_regions(0, num_regions_in_test);
 429 
 430   // Set up memory regions for the heap regions.
 431   MemRegion mr0(heap.start(), HeapRegion::GrainWords);
 432   MemRegion mr1(mr0.end(), HeapRegion::GrainWords);
 433   MemRegion mr2(mr1.end(), HeapRegion::GrainWords);
 434   MemRegion mr3(mr2.end(), HeapRegion::GrainWords);
 435   MemRegion mr4(mr3.end(), HeapRegion::GrainWords);
 436 
 437   HeapRegion hr0(0, &oa, mr0);
 438   HeapRegion hr1(1, &oa, mr1);
 439   HeapRegion hr2(2, &oa, mr2);
 440   HeapRegion hr3(3, &oa, mr3);
 441   HeapRegion hr4(4, &oa, mr4);
 442   l.add_ordered(&hr1);
 443   l.add_ordered(&hr0);
 444   l.add_ordered(&hr3);
 445   l.add_ordered(&hr4);
 446   l.add_ordered(&hr2);
 447   assert(l.length() == num_regions_in_test, "wrong length");
 448   l.verify_list();
 449 
 450   bot_storage->uncommit_regions(0, num_regions_in_test);
 451   delete bot_storage;
 452   FREE_C_HEAP_ARRAY(HeapWord, bot_data);
 453 }