space.cpp revision 13243:7235bc30c0d7
1/* 2 * Copyright (c) 1997, 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 "classfile/systemDictionary.hpp" 27#include "classfile/vmSymbols.hpp" 28#include "gc/serial/defNewGeneration.hpp" 29#include "gc/shared/blockOffsetTable.inline.hpp" 30#include "gc/shared/collectedHeap.inline.hpp" 31#include "gc/shared/genCollectedHeap.hpp" 32#include "gc/shared/genOopClosures.inline.hpp" 33#include "gc/shared/space.hpp" 34#include "gc/shared/space.inline.hpp" 35#include "gc/shared/spaceDecorator.hpp" 36#include "memory/universe.inline.hpp" 37#include "oops/oop.inline.hpp" 38#include "runtime/atomic.hpp" 39#include "runtime/java.hpp" 40#include "runtime/orderAccess.inline.hpp" 41#include "runtime/prefetch.inline.hpp" 42#include "runtime/safepoint.hpp" 43#include "utilities/copy.hpp" 44#include "utilities/globalDefinitions.hpp" 45#include "utilities/macros.hpp" 46 47HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top, 48 HeapWord* top_obj) { 49 if (top_obj != NULL) { 50 if (_sp->block_is_obj(top_obj)) { 51 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 52 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 53 // An arrayOop is starting on the dirty card - since we do exact 54 // store checks for objArrays we are done. 55 } else { 56 // Otherwise, it is possible that the object starting on the dirty 57 // card spans the entire card, and that the store happened on a 58 // later card. Figure out where the object ends. 59 // Use the block_size() method of the space over which 60 // the iteration is being done. That space (e.g. CMS) may have 61 // specific requirements on object sizes which will 62 // be reflected in the block_size() method. 63 top = top_obj + oop(top_obj)->size(); 64 } 65 } 66 } else { 67 top = top_obj; 68 } 69 } else { 70 assert(top == _sp->end(), "only case where top_obj == NULL"); 71 } 72 return top; 73} 74 75void DirtyCardToOopClosure::walk_mem_region(MemRegion mr, 76 HeapWord* bottom, 77 HeapWord* top) { 78 // 1. Blocks may or may not be objects. 79 // 2. Even when a block_is_obj(), it may not entirely 80 // occupy the block if the block quantum is larger than 81 // the object size. 82 // We can and should try to optimize by calling the non-MemRegion 83 // version of oop_iterate() for all but the extremal objects 84 // (for which we need to call the MemRegion version of 85 // oop_iterate()) To be done post-beta XXX 86 for (; bottom < top; bottom += _sp->block_size(bottom)) { 87 // As in the case of contiguous space above, we'd like to 88 // just use the value returned by oop_iterate to increment the 89 // current pointer; unfortunately, that won't work in CMS because 90 // we'd need an interface change (it seems) to have the space 91 // "adjust the object size" (for instance pad it up to its 92 // block alignment or minimum block size restrictions. XXX 93 if (_sp->block_is_obj(bottom) && 94 !_sp->obj_allocated_since_save_marks(oop(bottom))) { 95 oop(bottom)->oop_iterate(_cl, mr); 96 } 97 } 98} 99 100// We get called with "mr" representing the dirty region 101// that we want to process. Because of imprecise marking, 102// we may need to extend the incoming "mr" to the right, 103// and scan more. However, because we may already have 104// scanned some of that extended region, we may need to 105// trim its right-end back some so we do not scan what 106// we (or another worker thread) may already have scanned 107// or planning to scan. 108void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) { 109 110 // Some collectors need to do special things whenever their dirty 111 // cards are processed. For instance, CMS must remember mutator updates 112 // (i.e. dirty cards) so as to re-scan mutated objects. 113 // Such work can be piggy-backed here on dirty card scanning, so as to make 114 // it slightly more efficient than doing a complete non-destructive pre-scan 115 // of the card table. 116 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure(); 117 if (pCl != NULL) { 118 pCl->do_MemRegion(mr); 119 } 120 121 HeapWord* bottom = mr.start(); 122 HeapWord* last = mr.last(); 123 HeapWord* top = mr.end(); 124 HeapWord* bottom_obj; 125 HeapWord* top_obj; 126 127 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray || 128 _precision == CardTableModRefBS::Precise, 129 "Only ones we deal with for now."); 130 131 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray || 132 _cl->idempotent() || _last_bottom == NULL || 133 top <= _last_bottom, 134 "Not decreasing"); 135 NOT_PRODUCT(_last_bottom = mr.start()); 136 137 bottom_obj = _sp->block_start(bottom); 138 top_obj = _sp->block_start(last); 139 140 assert(bottom_obj <= bottom, "just checking"); 141 assert(top_obj <= top, "just checking"); 142 143 // Given what we think is the top of the memory region and 144 // the start of the object at the top, get the actual 145 // value of the top. 146 top = get_actual_top(top, top_obj); 147 148 // If the previous call did some part of this region, don't redo. 149 if (_precision == CardTableModRefBS::ObjHeadPreciseArray && 150 _min_done != NULL && 151 _min_done < top) { 152 top = _min_done; 153 } 154 155 // Top may have been reset, and in fact may be below bottom, 156 // e.g. the dirty card region is entirely in a now free object 157 // -- something that could happen with a concurrent sweeper. 158 bottom = MIN2(bottom, top); 159 MemRegion extended_mr = MemRegion(bottom, top); 160 assert(bottom <= top && 161 (_precision != CardTableModRefBS::ObjHeadPreciseArray || 162 _min_done == NULL || 163 top <= _min_done), 164 "overlap!"); 165 166 // Walk the region if it is not empty; otherwise there is nothing to do. 167 if (!extended_mr.is_empty()) { 168 walk_mem_region(extended_mr, bottom_obj, top); 169 } 170 171 // An idempotent closure might be applied in any order, so we don't 172 // record a _min_done for it. 173 if (!_cl->idempotent()) { 174 _min_done = bottom; 175 } else { 176 assert(_min_done == _last_explicit_min_done, 177 "Don't update _min_done for idempotent cl"); 178 } 179} 180 181DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl, 182 CardTableModRefBS::PrecisionStyle precision, 183 HeapWord* boundary, 184 bool parallel) { 185 return new DirtyCardToOopClosure(this, cl, precision, boundary); 186} 187 188HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top, 189 HeapWord* top_obj) { 190 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) { 191 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 192 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 193 // An arrayOop is starting on the dirty card - since we do exact 194 // store checks for objArrays we are done. 195 } else { 196 // Otherwise, it is possible that the object starting on the dirty 197 // card spans the entire card, and that the store happened on a 198 // later card. Figure out where the object ends. 199 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(), 200 "Block size and object size mismatch"); 201 top = top_obj + oop(top_obj)->size(); 202 } 203 } 204 } else { 205 top = (_sp->toContiguousSpace())->top(); 206 } 207 return top; 208} 209 210void FilteringDCTOC::walk_mem_region(MemRegion mr, 211 HeapWord* bottom, 212 HeapWord* top) { 213 // Note that this assumption won't hold if we have a concurrent 214 // collector in this space, which may have freed up objects after 215 // they were dirtied and before the stop-the-world GC that is 216 // examining cards here. 217 assert(bottom < top, "ought to be at least one obj on a dirty card."); 218 219 if (_boundary != NULL) { 220 // We have a boundary outside of which we don't want to look 221 // at objects, so create a filtering closure around the 222 // oop closure before walking the region. 223 FilteringClosure filter(_boundary, _cl); 224 walk_mem_region_with_cl(mr, bottom, top, &filter); 225 } else { 226 // No boundary, simply walk the heap with the oop closure. 227 walk_mem_region_with_cl(mr, bottom, top, _cl); 228 } 229 230} 231 232// We must replicate this so that the static type of "FilteringClosure" 233// (see above) is apparent at the oop_iterate calls. 234#define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ 235void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \ 236 HeapWord* bottom, \ 237 HeapWord* top, \ 238 ClosureType* cl) { \ 239 bottom += oop(bottom)->oop_iterate_size(cl, mr); \ 240 if (bottom < top) { \ 241 HeapWord* next_obj = bottom + oop(bottom)->size(); \ 242 while (next_obj < top) { \ 243 /* Bottom lies entirely below top, so we can call the */ \ 244 /* non-memRegion version of oop_iterate below. */ \ 245 oop(bottom)->oop_iterate(cl); \ 246 bottom = next_obj; \ 247 next_obj = bottom + oop(bottom)->size(); \ 248 } \ 249 /* Last object. */ \ 250 oop(bottom)->oop_iterate(cl, mr); \ 251 } \ 252} 253 254// (There are only two of these, rather than N, because the split is due 255// only to the introduction of the FilteringClosure, a local part of the 256// impl of this abstraction.) 257ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure) 258ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) 259 260DirtyCardToOopClosure* 261ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl, 262 CardTableModRefBS::PrecisionStyle precision, 263 HeapWord* boundary, 264 bool parallel) { 265 return new ContiguousSpaceDCTOC(this, cl, precision, boundary); 266} 267 268void Space::initialize(MemRegion mr, 269 bool clear_space, 270 bool mangle_space) { 271 HeapWord* bottom = mr.start(); 272 HeapWord* end = mr.end(); 273 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end), 274 "invalid space boundaries"); 275 set_bottom(bottom); 276 set_end(end); 277 if (clear_space) clear(mangle_space); 278} 279 280void Space::clear(bool mangle_space) { 281 if (ZapUnusedHeapArea && mangle_space) { 282 mangle_unused_area(); 283 } 284} 285 286ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL), 287 _concurrent_iteration_safe_limit(NULL) { 288 _mangler = new GenSpaceMangler(this); 289} 290 291ContiguousSpace::~ContiguousSpace() { 292 delete _mangler; 293} 294 295void ContiguousSpace::initialize(MemRegion mr, 296 bool clear_space, 297 bool mangle_space) 298{ 299 CompactibleSpace::initialize(mr, clear_space, mangle_space); 300 set_concurrent_iteration_safe_limit(top()); 301} 302 303void ContiguousSpace::clear(bool mangle_space) { 304 set_top(bottom()); 305 set_saved_mark(); 306 CompactibleSpace::clear(mangle_space); 307} 308 309bool ContiguousSpace::is_free_block(const HeapWord* p) const { 310 return p >= _top; 311} 312 313void OffsetTableContigSpace::clear(bool mangle_space) { 314 ContiguousSpace::clear(mangle_space); 315 _offsets.initialize_threshold(); 316} 317 318void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 319 Space::set_bottom(new_bottom); 320 _offsets.set_bottom(new_bottom); 321} 322 323void OffsetTableContigSpace::set_end(HeapWord* new_end) { 324 // Space should not advertise an increase in size 325 // until after the underlying offset table has been enlarged. 326 _offsets.resize(pointer_delta(new_end, bottom())); 327 Space::set_end(new_end); 328} 329 330#ifndef PRODUCT 331 332void ContiguousSpace::set_top_for_allocations(HeapWord* v) { 333 mangler()->set_top_for_allocations(v); 334} 335void ContiguousSpace::set_top_for_allocations() { 336 mangler()->set_top_for_allocations(top()); 337} 338void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) { 339 mangler()->check_mangled_unused_area(limit); 340} 341 342void ContiguousSpace::check_mangled_unused_area_complete() { 343 mangler()->check_mangled_unused_area_complete(); 344} 345 346// Mangled only the unused space that has not previously 347// been mangled and that has not been allocated since being 348// mangled. 349void ContiguousSpace::mangle_unused_area() { 350 mangler()->mangle_unused_area(); 351} 352void ContiguousSpace::mangle_unused_area_complete() { 353 mangler()->mangle_unused_area_complete(); 354} 355#endif // NOT_PRODUCT 356 357void CompactibleSpace::initialize(MemRegion mr, 358 bool clear_space, 359 bool mangle_space) { 360 Space::initialize(mr, clear_space, mangle_space); 361 set_compaction_top(bottom()); 362 _next_compaction_space = NULL; 363} 364 365void CompactibleSpace::clear(bool mangle_space) { 366 Space::clear(mangle_space); 367 _compaction_top = bottom(); 368} 369 370HeapWord* CompactibleSpace::forward(oop q, size_t size, 371 CompactPoint* cp, HeapWord* compact_top) { 372 // q is alive 373 // First check if we should switch compaction space 374 assert(this == cp->space, "'this' should be current compaction space."); 375 size_t compaction_max_size = pointer_delta(end(), compact_top); 376 while (size > compaction_max_size) { 377 // switch to next compaction space 378 cp->space->set_compaction_top(compact_top); 379 cp->space = cp->space->next_compaction_space(); 380 if (cp->space == NULL) { 381 cp->gen = GenCollectedHeap::heap()->young_gen(); 382 assert(cp->gen != NULL, "compaction must succeed"); 383 cp->space = cp->gen->first_compaction_space(); 384 assert(cp->space != NULL, "generation must have a first compaction space"); 385 } 386 compact_top = cp->space->bottom(); 387 cp->space->set_compaction_top(compact_top); 388 cp->threshold = cp->space->initialize_threshold(); 389 compaction_max_size = pointer_delta(cp->space->end(), compact_top); 390 } 391 392 // store the forwarding pointer into the mark word 393 if ((HeapWord*)q != compact_top) { 394 q->forward_to(oop(compact_top)); 395 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); 396 } else { 397 // if the object isn't moving we can just set the mark to the default 398 // mark and handle it specially later on. 399 q->init_mark(); 400 assert(q->forwardee() == NULL, "should be forwarded to NULL"); 401 } 402 403 compact_top += size; 404 405 // we need to update the offset table so that the beginnings of objects can be 406 // found during scavenge. Note that we are updating the offset table based on 407 // where the object will be once the compaction phase finishes. 408 if (compact_top > cp->threshold) 409 cp->threshold = 410 cp->space->cross_threshold(compact_top - size, compact_top); 411 return compact_top; 412} 413 414void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) { 415 scan_and_forward(this, cp); 416} 417 418void CompactibleSpace::adjust_pointers() { 419 // Check first is there is any work to do. 420 if (used() == 0) { 421 return; // Nothing to do. 422 } 423 424 scan_and_adjust_pointers(this); 425} 426 427void CompactibleSpace::compact() { 428 scan_and_compact(this); 429} 430 431void Space::print_short() const { print_short_on(tty); } 432 433void Space::print_short_on(outputStream* st) const { 434 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K, 435 (int) ((double) used() * 100 / capacity())); 436} 437 438void Space::print() const { print_on(tty); } 439 440void Space::print_on(outputStream* st) const { 441 print_short_on(st); 442 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")", 443 p2i(bottom()), p2i(end())); 444} 445 446void ContiguousSpace::print_on(outputStream* st) const { 447 print_short_on(st); 448 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 449 p2i(bottom()), p2i(top()), p2i(end())); 450} 451 452void OffsetTableContigSpace::print_on(outputStream* st) const { 453 print_short_on(st); 454 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 455 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 456 p2i(bottom()), p2i(top()), p2i(_offsets.threshold()), p2i(end())); 457} 458 459void ContiguousSpace::verify() const { 460 HeapWord* p = bottom(); 461 HeapWord* t = top(); 462 HeapWord* prev_p = NULL; 463 while (p < t) { 464 oop(p)->verify(); 465 prev_p = p; 466 p += oop(p)->size(); 467 } 468 guarantee(p == top(), "end of last object must match end of space"); 469 if (top() != end()) { 470 guarantee(top() == block_start_const(end()-1) && 471 top() == block_start_const(top()), 472 "top should be start of unallocated block, if it exists"); 473 } 474} 475 476void Space::oop_iterate(ExtendedOopClosure* blk) { 477 ObjectToOopClosure blk2(blk); 478 object_iterate(&blk2); 479} 480 481bool Space::obj_is_alive(const HeapWord* p) const { 482 assert (block_is_obj(p), "The address should point to an object"); 483 return true; 484} 485 486#if INCLUDE_ALL_GCS 487#define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \ 488 \ 489 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\ 490 HeapWord* obj_addr = mr.start(); \ 491 HeapWord* t = mr.end(); \ 492 while (obj_addr < t) { \ 493 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \ 494 obj_addr += oop(obj_addr)->oop_iterate_size(blk); \ 495 } \ 496 } 497 498 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN) 499 500#undef ContigSpace_PAR_OOP_ITERATE_DEFN 501#endif // INCLUDE_ALL_GCS 502 503void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) { 504 if (is_empty()) return; 505 HeapWord* obj_addr = bottom(); 506 HeapWord* t = top(); 507 // Could call objects iterate, but this is easier. 508 while (obj_addr < t) { 509 obj_addr += oop(obj_addr)->oop_iterate_size(blk); 510 } 511} 512 513void ContiguousSpace::object_iterate(ObjectClosure* blk) { 514 if (is_empty()) return; 515 object_iterate_from(bottom(), blk); 516} 517 518// For a ContiguousSpace object_iterate() and safe_object_iterate() 519// are the same. 520void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) { 521 object_iterate(blk); 522} 523 524void ContiguousSpace::object_iterate_from(HeapWord* mark, ObjectClosure* blk) { 525 while (mark < top()) { 526 blk->do_object(oop(mark)); 527 mark += oop(mark)->size(); 528 } 529} 530 531HeapWord* 532ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) { 533 HeapWord * limit = concurrent_iteration_safe_limit(); 534 assert(limit <= top(), "sanity check"); 535 for (HeapWord* p = bottom(); p < limit;) { 536 size_t size = blk->do_object_careful(oop(p)); 537 if (size == 0) { 538 return p; // failed at p 539 } else { 540 p += size; 541 } 542 } 543 return NULL; // all done 544} 545 546#define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ 547 \ 548void ContiguousSpace:: \ 549oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ 550 HeapWord* t; \ 551 HeapWord* p = saved_mark_word(); \ 552 assert(p != NULL, "expected saved mark"); \ 553 \ 554 const intx interval = PrefetchScanIntervalInBytes; \ 555 do { \ 556 t = top(); \ 557 while (p < t) { \ 558 Prefetch::write(p, interval); \ 559 debug_only(HeapWord* prev = p); \ 560 oop m = oop(p); \ 561 p += m->oop_iterate_size(blk); \ 562 } \ 563 } while (t < top()); \ 564 \ 565 set_saved_mark_word(p); \ 566} 567 568ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN) 569 570#undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN 571 572// Very general, slow implementation. 573HeapWord* ContiguousSpace::block_start_const(const void* p) const { 574 assert(MemRegion(bottom(), end()).contains(p), 575 "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 576 p2i(p), p2i(bottom()), p2i(end())); 577 if (p >= top()) { 578 return top(); 579 } else { 580 HeapWord* last = bottom(); 581 HeapWord* cur = last; 582 while (cur <= p) { 583 last = cur; 584 cur += oop(cur)->size(); 585 } 586 assert(oop(last)->is_oop(), PTR_FORMAT " should be an object start", p2i(last)); 587 return last; 588 } 589} 590 591size_t ContiguousSpace::block_size(const HeapWord* p) const { 592 assert(MemRegion(bottom(), end()).contains(p), 593 "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 594 p2i(p), p2i(bottom()), p2i(end())); 595 HeapWord* current_top = top(); 596 assert(p <= current_top, 597 "p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT, 598 p2i(p), p2i(current_top)); 599 assert(p == current_top || oop(p)->is_oop(), 600 "p (" PTR_FORMAT ") is not a block start - " 601 "current_top: " PTR_FORMAT ", is_oop: %s", 602 p2i(p), p2i(current_top), BOOL_TO_STR(oop(p)->is_oop())); 603 if (p < current_top) { 604 return oop(p)->size(); 605 } else { 606 assert(p == current_top, "just checking"); 607 return pointer_delta(end(), (HeapWord*) p); 608 } 609} 610 611// This version requires locking. 612inline HeapWord* ContiguousSpace::allocate_impl(size_t size) { 613 assert(Heap_lock->owned_by_self() || 614 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), 615 "not locked"); 616 HeapWord* obj = top(); 617 if (pointer_delta(end(), obj) >= size) { 618 HeapWord* new_top = obj + size; 619 set_top(new_top); 620 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 621 return obj; 622 } else { 623 return NULL; 624 } 625} 626 627// This version is lock-free. 628inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size) { 629 do { 630 HeapWord* obj = top(); 631 if (pointer_delta(end(), obj) >= size) { 632 HeapWord* new_top = obj + size; 633 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); 634 // result can be one of two: 635 // the old top value: the exchange succeeded 636 // otherwise: the new value of the top is returned. 637 if (result == obj) { 638 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 639 return obj; 640 } 641 } else { 642 return NULL; 643 } 644 } while (true); 645} 646 647HeapWord* ContiguousSpace::allocate_aligned(size_t size) { 648 assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked"); 649 HeapWord* end_value = end(); 650 651 HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes); 652 if (obj == NULL) { 653 return NULL; 654 } 655 656 if (pointer_delta(end_value, obj) >= size) { 657 HeapWord* new_top = obj + size; 658 set_top(new_top); 659 assert(::is_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top), 660 "checking alignment"); 661 return obj; 662 } else { 663 set_top(obj); 664 return NULL; 665 } 666} 667 668// Requires locking. 669HeapWord* ContiguousSpace::allocate(size_t size) { 670 return allocate_impl(size); 671} 672 673// Lock-free. 674HeapWord* ContiguousSpace::par_allocate(size_t size) { 675 return par_allocate_impl(size); 676} 677 678void ContiguousSpace::allocate_temporary_filler(int factor) { 679 // allocate temporary type array decreasing free size with factor 'factor' 680 assert(factor >= 0, "just checking"); 681 size_t size = pointer_delta(end(), top()); 682 683 // if space is full, return 684 if (size == 0) return; 685 686 if (factor > 0) { 687 size -= size/factor; 688 } 689 size = align_object_size(size); 690 691 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT); 692 if (size >= align_object_size(array_header_size)) { 693 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint)); 694 // allocate uninitialized int array 695 typeArrayOop t = (typeArrayOop) allocate(size); 696 assert(t != NULL, "allocation should succeed"); 697 t->set_mark(markOopDesc::prototype()); 698 t->set_klass(Universe::intArrayKlassObj()); 699 t->set_length((int)length); 700 } else { 701 assert(size == CollectedHeap::min_fill_size(), 702 "size for smallest fake object doesn't match"); 703 instanceOop obj = (instanceOop) allocate(size); 704 obj->set_mark(markOopDesc::prototype()); 705 obj->set_klass_gap(0); 706 obj->set_klass(SystemDictionary::Object_klass()); 707 } 708} 709 710HeapWord* OffsetTableContigSpace::initialize_threshold() { 711 return _offsets.initialize_threshold(); 712} 713 714HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) { 715 _offsets.alloc_block(start, end); 716 return _offsets.threshold(); 717} 718 719OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray, 720 MemRegion mr) : 721 _offsets(sharedOffsetArray, mr), 722 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true) 723{ 724 _offsets.set_contig_space(this); 725 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); 726} 727 728#define OBJ_SAMPLE_INTERVAL 0 729#define BLOCK_SAMPLE_INTERVAL 100 730 731void OffsetTableContigSpace::verify() const { 732 HeapWord* p = bottom(); 733 HeapWord* prev_p = NULL; 734 int objs = 0; 735 int blocks = 0; 736 737 if (VerifyObjectStartArray) { 738 _offsets.verify(); 739 } 740 741 while (p < top()) { 742 size_t size = oop(p)->size(); 743 // For a sampling of objects in the space, find it using the 744 // block offset table. 745 if (blocks == BLOCK_SAMPLE_INTERVAL) { 746 guarantee(p == block_start_const(p + (size/2)), 747 "check offset computation"); 748 blocks = 0; 749 } else { 750 blocks++; 751 } 752 753 if (objs == OBJ_SAMPLE_INTERVAL) { 754 oop(p)->verify(); 755 objs = 0; 756 } else { 757 objs++; 758 } 759 prev_p = p; 760 p += size; 761 } 762 guarantee(p == top(), "end of last object must match end of space"); 763} 764 765 766size_t TenuredSpace::allowed_dead_ratio() const { 767 return MarkSweepDeadRatio; 768} 769