1 /*
2 * Copyright (c) 1997, 2018, 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.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/align.hpp"
44 #include "utilities/copy.hpp"
45 #include "utilities/globalDefinitions.hpp"
46 #include "utilities/macros.hpp"
47
48 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
49 HeapWord* top_obj) {
50 if (top_obj != NULL) {
51 if (_sp->block_is_obj(top_obj)) {
52 if (_precision == CardTable::ObjHeadPreciseArray) {
53 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
54 // An arrayOop is starting on the dirty card - since we do exact
55 // store checks for objArrays we are done.
56 } else {
57 // Otherwise, it is possible that the object starting on the dirty
58 // card spans the entire card, and that the store happened on a
59 // later card. Figure out where the object ends.
60 // Use the block_size() method of the space over which
61 // the iteration is being done. That space (e.g. CMS) may have
62 // specific requirements on object sizes which will
63 // be reflected in the block_size() method.
64 top = top_obj + oop(top_obj)->size();
65 }
66 }
67 } else {
68 top = top_obj;
69 }
70 } else {
71 assert(top == _sp->end(), "only case where top_obj == NULL");
72 }
73 return top;
74 }
75
76 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
77 HeapWord* bottom,
78 HeapWord* top) {
79 // 1. Blocks may or may not be objects.
80 // 2. Even when a block_is_obj(), it may not entirely
81 // occupy the block if the block quantum is larger than
82 // the object size.
83 // We can and should try to optimize by calling the non-MemRegion
84 // version of oop_iterate() for all but the extremal objects
85 // (for which we need to call the MemRegion version of
86 // oop_iterate()) To be done post-beta XXX
87 for (; bottom < top; bottom += _sp->block_size(bottom)) {
88 // As in the case of contiguous space above, we'd like to
89 // just use the value returned by oop_iterate to increment the
90 // current pointer; unfortunately, that won't work in CMS because
91 // we'd need an interface change (it seems) to have the space
92 // "adjust the object size" (for instance pad it up to its
93 // block alignment or minimum block size restrictions. XXX
94 if (_sp->block_is_obj(bottom) &&
95 !_sp->obj_allocated_since_save_marks(oop(bottom))) {
96 oop(bottom)->oop_iterate(_cl, mr);
97 }
98 }
99 }
100
101 // We get called with "mr" representing the dirty region
102 // that we want to process. Because of imprecise marking,
103 // we may need to extend the incoming "mr" to the right,
104 // and scan more. However, because we may already have
105 // scanned some of that extended region, we may need to
106 // trim its right-end back some so we do not scan what
107 // we (or another worker thread) may already have scanned
108 // or planning to scan.
109 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
110
111 // Some collectors need to do special things whenever their dirty
112 // cards are processed. For instance, CMS must remember mutator updates
113 // (i.e. dirty cards) so as to re-scan mutated objects.
114 // Such work can be piggy-backed here on dirty card scanning, so as to make
115 // it slightly more efficient than doing a complete non-destructive pre-scan
116 // of the card table.
117 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
118 if (pCl != NULL) {
119 pCl->do_MemRegion(mr);
120 }
121
122 HeapWord* bottom = mr.start();
123 HeapWord* last = mr.last();
124 HeapWord* top = mr.end();
125 HeapWord* bottom_obj;
126 HeapWord* top_obj;
127
128 assert(_precision == CardTable::ObjHeadPreciseArray ||
129 _precision == CardTable::Precise,
130 "Only ones we deal with for now.");
131
132 assert(_precision != CardTable::ObjHeadPreciseArray ||
133 _cl->idempotent() || _last_bottom == NULL ||
134 top <= _last_bottom,
135 "Not decreasing");
136 NOT_PRODUCT(_last_bottom = mr.start());
137
138 bottom_obj = _sp->block_start(bottom);
139 top_obj = _sp->block_start(last);
140
141 assert(bottom_obj <= bottom, "just checking");
142 assert(top_obj <= top, "just checking");
143
144 // Given what we think is the top of the memory region and
145 // the start of the object at the top, get the actual
146 // value of the top.
147 top = get_actual_top(top, top_obj);
148
149 // If the previous call did some part of this region, don't redo.
150 if (_precision == CardTable::ObjHeadPreciseArray &&
151 _min_done != NULL &&
152 _min_done < top) {
153 top = _min_done;
154 }
155
156 // Top may have been reset, and in fact may be below bottom,
157 // e.g. the dirty card region is entirely in a now free object
158 // -- something that could happen with a concurrent sweeper.
159 bottom = MIN2(bottom, top);
160 MemRegion extended_mr = MemRegion(bottom, top);
161 assert(bottom <= top &&
162 (_precision != CardTable::ObjHeadPreciseArray ||
163 _min_done == NULL ||
164 top <= _min_done),
165 "overlap!");
166
167 // Walk the region if it is not empty; otherwise there is nothing to do.
168 if (!extended_mr.is_empty()) {
169 walk_mem_region(extended_mr, bottom_obj, top);
170 }
171
172 // An idempotent closure might be applied in any order, so we don't
173 // record a _min_done for it.
174 if (!_cl->idempotent()) {
175 _min_done = bottom;
176 } else {
177 assert(_min_done == _last_explicit_min_done,
178 "Don't update _min_done for idempotent cl");
179 }
180 }
181
182 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
183 CardTable::PrecisionStyle precision,
184 HeapWord* boundary,
185 bool parallel) {
186 return new DirtyCardToOopClosure(this, cl, precision, boundary);
187 }
188
189 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
190 HeapWord* top_obj) {
191 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
192 if (_precision == CardTable::ObjHeadPreciseArray) {
193 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
194 // An arrayOop is starting on the dirty card - since we do exact
195 // store checks for objArrays we are done.
196 } else {
197 // Otherwise, it is possible that the object starting on the dirty
198 // card spans the entire card, and that the store happened on a
199 // later card. Figure out where the object ends.
200 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
201 "Block size and object size mismatch");
202 top = top_obj + oop(top_obj)->size();
203 }
204 }
205 } else {
206 top = (_sp->toContiguousSpace())->top();
207 }
208 return top;
209 }
210
211 void FilteringDCTOC::walk_mem_region(MemRegion mr,
212 HeapWord* bottom,
213 HeapWord* top) {
214 // Note that this assumption won't hold if we have a concurrent
215 // collector in this space, which may have freed up objects after
216 // they were dirtied and before the stop-the-world GC that is
217 // examining cards here.
218 assert(bottom < top, "ought to be at least one obj on a dirty card.");
219
220 if (_boundary != NULL) {
221 // We have a boundary outside of which we don't want to look
222 // at objects, so create a filtering closure around the
223 // oop closure before walking the region.
224 FilteringClosure filter(_boundary, _cl);
225 walk_mem_region_with_cl(mr, bottom, top, &filter);
226 } else {
227 // No boundary, simply walk the heap with the oop closure.
228 walk_mem_region_with_cl(mr, bottom, top, _cl);
229 }
230
231 }
232
233 // We must replicate this so that the static type of "FilteringClosure"
234 // (see above) is apparent at the oop_iterate calls.
235 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
236 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
237 HeapWord* bottom, \
238 HeapWord* top, \
239 ClosureType* cl) { \
240 bottom += oop(bottom)->oop_iterate_size(cl, mr); \
241 if (bottom < top) { \
242 HeapWord* next_obj = bottom + oop(bottom)->size(); \
243 while (next_obj < top) { \
244 /* Bottom lies entirely below top, so we can call the */ \
245 /* non-memRegion version of oop_iterate below. */ \
246 oop(bottom)->oop_iterate(cl); \
247 bottom = next_obj; \
248 next_obj = bottom + oop(bottom)->size(); \
249 } \
250 /* Last object. */ \
251 oop(bottom)->oop_iterate(cl, mr); \
252 } \
253 }
254
255 // (There are only two of these, rather than N, because the split is due
256 // only to the introduction of the FilteringClosure, a local part of the
257 // impl of this abstraction.)
258 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
259 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
260
261 DirtyCardToOopClosure*
262 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
263 CardTable::PrecisionStyle precision,
264 HeapWord* boundary,
265 bool parallel) {
266 return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
267 }
268
269 void Space::initialize(MemRegion mr,
270 bool clear_space,
271 bool mangle_space) {
272 HeapWord* bottom = mr.start();
273 HeapWord* end = mr.end();
274 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
275 "invalid space boundaries");
276 set_bottom(bottom);
277 set_end(end);
278 if (clear_space) clear(mangle_space);
279 }
280
281 void Space::clear(bool mangle_space) {
282 if (ZapUnusedHeapArea && mangle_space) {
283 mangle_unused_area();
284 }
285 }
286
287 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
288 _concurrent_iteration_safe_limit(NULL) {
289 _mangler = new GenSpaceMangler(this);
290 }
291
292 ContiguousSpace::~ContiguousSpace() {
293 delete _mangler;
294 }
295
296 void ContiguousSpace::initialize(MemRegion mr,
297 bool clear_space,
298 bool mangle_space)
299 {
300 CompactibleSpace::initialize(mr, clear_space, mangle_space);
301 set_concurrent_iteration_safe_limit(top());
302 }
303
304 void ContiguousSpace::clear(bool mangle_space) {
305 set_top(bottom());
306 set_saved_mark();
307 CompactibleSpace::clear(mangle_space);
308 }
309
310 bool ContiguousSpace::is_free_block(const HeapWord* p) const {
311 return p >= _top;
312 }
313
314 void OffsetTableContigSpace::clear(bool mangle_space) {
315 ContiguousSpace::clear(mangle_space);
316 _offsets.initialize_threshold();
317 }
318
319 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
320 Space::set_bottom(new_bottom);
321 _offsets.set_bottom(new_bottom);
322 }
323
324 void OffsetTableContigSpace::set_end(HeapWord* new_end) {
325 // Space should not advertise an increase in size
326 // until after the underlying offset table has been enlarged.
327 _offsets.resize(pointer_delta(new_end, bottom()));
328 Space::set_end(new_end);
329 }
330
331 #ifndef PRODUCT
332
333 void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
334 mangler()->set_top_for_allocations(v);
335 }
336 void ContiguousSpace::set_top_for_allocations() {
337 mangler()->set_top_for_allocations(top());
338 }
339 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
340 mangler()->check_mangled_unused_area(limit);
341 }
342
343 void ContiguousSpace::check_mangled_unused_area_complete() {
344 mangler()->check_mangled_unused_area_complete();
345 }
346
347 // Mangled only the unused space that has not previously
348 // been mangled and that has not been allocated since being
349 // mangled.
350 void ContiguousSpace::mangle_unused_area() {
351 mangler()->mangle_unused_area();
352 }
353 void ContiguousSpace::mangle_unused_area_complete() {
354 mangler()->mangle_unused_area_complete();
355 }
356 #endif // NOT_PRODUCT
357
358 void CompactibleSpace::initialize(MemRegion mr,
359 bool clear_space,
360 bool mangle_space) {
361 Space::initialize(mr, clear_space, mangle_space);
362 set_compaction_top(bottom());
363 _next_compaction_space = NULL;
364 }
365
366 void CompactibleSpace::clear(bool mangle_space) {
367 Space::clear(mangle_space);
368 _compaction_top = bottom();
369 }
370
371 HeapWord* CompactibleSpace::forward(oop q, size_t size,
372 CompactPoint* cp, HeapWord* compact_top) {
373 // q is alive
374 // First check if we should switch compaction space
375 assert(this == cp->space, "'this' should be current compaction space.");
376 size_t compaction_max_size = pointer_delta(end(), compact_top);
377 while (size > compaction_max_size) {
378 // switch to next compaction space
379 cp->space->set_compaction_top(compact_top);
380 cp->space = cp->space->next_compaction_space();
381 if (cp->space == NULL) {
382 cp->gen = GenCollectedHeap::heap()->young_gen();
383 assert(cp->gen != NULL, "compaction must succeed");
384 cp->space = cp->gen->first_compaction_space();
385 assert(cp->space != NULL, "generation must have a first compaction space");
386 }
387 compact_top = cp->space->bottom();
388 cp->space->set_compaction_top(compact_top);
389 cp->threshold = cp->space->initialize_threshold();
390 compaction_max_size = pointer_delta(cp->space->end(), compact_top);
391 }
392
393 // store the forwarding pointer into the mark word
394 if ((HeapWord*)q != compact_top) {
395 q->forward_to(oop(compact_top));
396 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
397 } else {
398 // if the object isn't moving we can just set the mark to the default
399 // mark and handle it specially later on.
400 q->init_mark_raw();
401 assert(q->forwardee() == NULL, "should be forwarded to NULL");
402 }
403
404 compact_top += size;
405
406 // we need to update the offset table so that the beginnings of objects can be
407 // found during scavenge. Note that we are updating the offset table based on
408 // where the object will be once the compaction phase finishes.
409 if (compact_top > cp->threshold)
410 cp->threshold =
411 cp->space->cross_threshold(compact_top - size, compact_top);
412 return compact_top;
413 }
414
415 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
416 scan_and_forward(this, cp);
417 }
418
419 void CompactibleSpace::adjust_pointers() {
420 // Check first is there is any work to do.
421 if (used() == 0) {
422 return; // Nothing to do.
423 }
424
425 scan_and_adjust_pointers(this);
426 }
427
428 void CompactibleSpace::compact() {
429 scan_and_compact(this);
430 }
431
432 void Space::print_short() const { print_short_on(tty); }
433
434 void Space::print_short_on(outputStream* st) const {
435 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
436 (int) ((double) used() * 100 / capacity()));
437 }
438
439 void Space::print() const { print_on(tty); }
440
441 void Space::print_on(outputStream* st) const {
442 print_short_on(st);
443 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
444 p2i(bottom()), p2i(end()));
445 }
446
447 void ContiguousSpace::print_on(outputStream* st) const {
448 print_short_on(st);
449 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
450 p2i(bottom()), p2i(top()), p2i(end()));
451 }
452
453 void OffsetTableContigSpace::print_on(outputStream* st) const {
454 print_short_on(st);
455 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
456 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
457 p2i(bottom()), p2i(top()), p2i(_offsets.threshold()), p2i(end()));
458 }
459
460 void ContiguousSpace::verify() const {
461 HeapWord* p = bottom();
462 HeapWord* t = top();
463 HeapWord* prev_p = NULL;
464 while (p < t) {
465 oop(p)->verify();
466 prev_p = p;
467 p += oop(p)->size();
468 }
469 guarantee(p == top(), "end of last object must match end of space");
470 if (top() != end()) {
471 guarantee(top() == block_start_const(end()-1) &&
472 top() == block_start_const(top()),
473 "top should be start of unallocated block, if it exists");
474 }
475 }
476
477 void Space::oop_iterate(ExtendedOopClosure* blk) {
478 ObjectToOopClosure blk2(blk);
479 object_iterate(&blk2);
480 }
481
482 bool Space::obj_is_alive(const HeapWord* p) const {
483 assert (block_is_obj(p), "The address should point to an object");
484 return true;
485 }
486
487 #if INCLUDE_ALL_GCS
488 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
489 \
490 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
491 HeapWord* obj_addr = mr.start(); \
492 HeapWord* t = mr.end(); \
493 while (obj_addr < t) { \
494 assert(oopDesc::is_oop(oop(obj_addr)), "Should be an oop"); \
495 obj_addr += oop(obj_addr)->oop_iterate_size(blk); \
496 } \
497 }
498
499 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
500
501 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
502 #endif // INCLUDE_ALL_GCS
503
504 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
505 if (is_empty()) return;
506 HeapWord* obj_addr = bottom();
507 HeapWord* t = top();
508 // Could call objects iterate, but this is easier.
509 while (obj_addr < t) {
510 obj_addr += oop(obj_addr)->oop_iterate_size(blk);
511 }
512 }
513
514 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
515 if (is_empty()) return;
516 object_iterate_from(bottom(), blk);
517 }
518
519 // For a ContiguousSpace object_iterate() and safe_object_iterate()
520 // are the same.
521 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
522 object_iterate(blk);
523 }
524
525 void ContiguousSpace::object_iterate_from(HeapWord* mark, ObjectClosure* blk) {
526 while (mark < top()) {
527 blk->do_object(oop(mark));
528 mark += oop(mark)->size();
529 }
530 }
531
532 HeapWord*
533 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
534 HeapWord * limit = concurrent_iteration_safe_limit();
535 assert(limit <= top(), "sanity check");
536 for (HeapWord* p = bottom(); p < limit;) {
537 size_t size = blk->do_object_careful(oop(p));
538 if (size == 0) {
539 return p; // failed at p
540 } else {
541 p += size;
542 }
543 }
544 return NULL; // all done
545 }
546
547 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
548 \
549 void ContiguousSpace:: \
550 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
551 HeapWord* t; \
552 HeapWord* p = saved_mark_word(); \
553 assert(p != NULL, "expected saved mark"); \
554 \
555 const intx interval = PrefetchScanIntervalInBytes; \
556 do { \
557 t = top(); \
558 while (p < t) { \
559 Prefetch::write(p, interval); \
560 debug_only(HeapWord* prev = p); \
561 oop m = oop(p); \
562 p += m->oop_iterate_size(blk); \
563 } \
564 } while (t < top()); \
565 \
566 set_saved_mark_word(p); \
567 }
568
569 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
570
571 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
572
573 // Very general, slow implementation.
574 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
575 assert(MemRegion(bottom(), end()).contains(p),
576 "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
577 p2i(p), p2i(bottom()), p2i(end()));
578 if (p >= top()) {
579 return top();
580 } else {
581 HeapWord* last = bottom();
582 HeapWord* cur = last;
583 while (cur <= p) {
584 last = cur;
585 cur += oop(cur)->size();
586 }
587 assert(oopDesc::is_oop(oop(last)), PTR_FORMAT " should be an object start", p2i(last));
588 return last;
589 }
590 }
591
592 size_t ContiguousSpace::block_size(const HeapWord* p) const {
593 assert(MemRegion(bottom(), end()).contains(p),
594 "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
595 p2i(p), p2i(bottom()), p2i(end()));
596 HeapWord* current_top = top();
597 assert(p <= current_top,
598 "p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
599 p2i(p), p2i(current_top));
600 assert(p == current_top || oopDesc::is_oop(oop(p)),
601 "p (" PTR_FORMAT ") is not a block start - "
602 "current_top: " PTR_FORMAT ", is_oop: %s",
603 p2i(p), p2i(current_top), BOOL_TO_STR(oopDesc::is_oop(oop(p))));
604 if (p < current_top) {
605 return oop(p)->size();
606 } else {
607 assert(p == current_top, "just checking");
608 return pointer_delta(end(), (HeapWord*) p);
609 }
610 }
611
612 // This version requires locking.
613 inline HeapWord* ContiguousSpace::allocate_impl(size_t size) {
614 assert(Heap_lock->owned_by_self() ||
615 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()),
616 "not locked");
617 HeapWord* obj = top();
618 if (pointer_delta(end(), obj) >= size) {
619 HeapWord* new_top = obj + size;
620 set_top(new_top);
621 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
622 return obj;
623 } else {
624 return NULL;
625 }
626 }
627
628 // This version is lock-free.
629 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size) {
630 do {
631 HeapWord* obj = top();
632 if (pointer_delta(end(), obj) >= size) {
633 HeapWord* new_top = obj + size;
634 HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj);
635 // result can be one of two:
636 // the old top value: the exchange succeeded
637 // otherwise: the new value of the top is returned.
638 if (result == obj) {
639 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
640 return obj;
641 }
642 } else {
643 return NULL;
644 }
645 } while (true);
646 }
647
648 HeapWord* ContiguousSpace::allocate_aligned(size_t size) {
649 assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked");
650 HeapWord* end_value = end();
651
652 HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes);
653 if (obj == NULL) {
654 return NULL;
655 }
656
657 if (pointer_delta(end_value, obj) >= size) {
658 HeapWord* new_top = obj + size;
659 set_top(new_top);
660 assert(::is_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top),
661 "checking alignment");
662 return obj;
663 } else {
664 set_top(obj);
665 return NULL;
666 }
667 }
668
669 // Requires locking.
670 HeapWord* ContiguousSpace::allocate(size_t size) {
671 return allocate_impl(size);
672 }
673
674 // Lock-free.
675 HeapWord* ContiguousSpace::par_allocate(size_t size) {
676 return par_allocate_impl(size);
677 }
678
679 void ContiguousSpace::allocate_temporary_filler(int factor) {
680 // allocate temporary type array decreasing free size with factor 'factor'
681 assert(factor >= 0, "just checking");
682 size_t size = pointer_delta(end(), top());
683
684 // if space is full, return
685 if (size == 0) return;
686
687 if (factor > 0) {
688 size -= size/factor;
689 }
690 size = align_object_size(size);
691
692 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
693 if (size >= align_object_size(array_header_size)) {
694 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
695 // allocate uninitialized int array
696 typeArrayOop t = (typeArrayOop) allocate(size);
697 assert(t != NULL, "allocation should succeed");
698 t->set_mark_raw(markOopDesc::prototype());
699 t->set_klass(Universe::intArrayKlassObj());
700 t->set_length((int)length);
701 } else {
702 assert(size == CollectedHeap::min_fill_size(),
703 "size for smallest fake object doesn't match");
704 instanceOop obj = (instanceOop) allocate(size);
705 obj->set_mark_raw(markOopDesc::prototype());
706 obj->set_klass_gap(0);
707 obj->set_klass(SystemDictionary::Object_klass());
708 }
709 }
710
711 HeapWord* OffsetTableContigSpace::initialize_threshold() {
712 return _offsets.initialize_threshold();
713 }
714
715 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
716 _offsets.alloc_block(start, end);
717 return _offsets.threshold();
718 }
719
720 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
721 MemRegion mr) :
722 _offsets(sharedOffsetArray, mr),
723 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
724 {
725 _offsets.set_contig_space(this);
726 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
727 }
728
729 #define OBJ_SAMPLE_INTERVAL 0
730 #define BLOCK_SAMPLE_INTERVAL 100
731
732 void OffsetTableContigSpace::verify() const {
733 HeapWord* p = bottom();
734 HeapWord* prev_p = NULL;
735 int objs = 0;
736 int blocks = 0;
737
738 if (VerifyObjectStartArray) {
739 _offsets.verify();
740 }
741
742 while (p < top()) {
743 size_t size = oop(p)->size();
744 // For a sampling of objects in the space, find it using the
745 // block offset table.
746 if (blocks == BLOCK_SAMPLE_INTERVAL) {
747 guarantee(p == block_start_const(p + (size/2)),
748 "check offset computation");
749 blocks = 0;
750 } else {
751 blocks++;
752 }
753
754 if (objs == OBJ_SAMPLE_INTERVAL) {
755 oop(p)->verify();
756 objs = 0;
757 } else {
758 objs++;
759 }
760 prev_p = p;
761 p += size;
762 }
763 guarantee(p == top(), "end of last object must match end of space");
764 }
765
766
767 size_t TenuredSpace::allowed_dead_ratio() const {
768 return MarkSweepDeadRatio;
769 }