/* * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ #include "incls/_precompiled.incl" #include "incls/_heapRegion.cpp.incl" HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1, HeapRegion* hr, OopClosure* cl, CardTableModRefBS::PrecisionStyle precision, FilterKind fk) : ContiguousSpaceDCTOC(hr, cl, precision, NULL), _hr(hr), _fk(fk), _g1(g1) {} FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r, OopClosure* oc) : _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc), _out_of_region(0) {} class VerifyLiveClosure: public OopClosure { G1CollectedHeap* _g1h; CardTableModRefBS* _bs; oop _containing_obj; bool _failures; int _n_failures; public: VerifyLiveClosure(G1CollectedHeap* g1h) : _g1h(g1h), _bs(NULL), _containing_obj(NULL), _failures(false), _n_failures(0) { BarrierSet* bs = _g1h->barrier_set(); if (bs->is_a(BarrierSet::CardTableModRef)) _bs = (CardTableModRefBS*)bs; } void set_containing_obj(oop obj) { _containing_obj = obj; } bool failures() { return _failures; } int n_failures() { return _n_failures; } virtual void do_oop(narrowOop* p) { guarantee(false, "NYI"); } void do_oop(oop* p) { assert(_containing_obj != NULL, "Precondition"); assert(!_g1h->is_obj_dead(_containing_obj), "Precondition"); oop obj = *p; if (obj != NULL) { bool failed = false; if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead(obj)) { if (!_failures) { gclog_or_tty->print_cr(""); gclog_or_tty->print_cr("----------"); } if (!_g1h->is_in_closed_subset(obj)) { gclog_or_tty->print_cr("Field "PTR_FORMAT " of live obj "PTR_FORMAT " points to obj "PTR_FORMAT " not in the heap.", p, (void*) _containing_obj, (void*) obj); } else { gclog_or_tty->print_cr("Field "PTR_FORMAT " of live obj "PTR_FORMAT " points to dead obj "PTR_FORMAT".", p, (void*) _containing_obj, (void*) obj); } gclog_or_tty->print_cr("Live obj:"); _containing_obj->print_on(gclog_or_tty); gclog_or_tty->print_cr("Bad referent:"); obj->print_on(gclog_or_tty); gclog_or_tty->print_cr("----------"); _failures = true; failed = true; _n_failures++; } if (!_g1h->full_collection()) { HeapRegion* from = _g1h->heap_region_containing(p); HeapRegion* to = _g1h->heap_region_containing(*p); if (from != NULL && to != NULL && from != to && !to->popular() && !to->isHumongous()) { jbyte cv_obj = *_bs->byte_for_const(_containing_obj); jbyte cv_field = *_bs->byte_for_const(p); const jbyte dirty = CardTableModRefBS::dirty_card_val(); bool is_bad = !(from->is_young() || to->rem_set()->contains_reference(p) || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed (_containing_obj->is_objArray() ? cv_field == dirty : cv_obj == dirty || cv_field == dirty)); if (is_bad) { if (!_failures) { gclog_or_tty->print_cr(""); gclog_or_tty->print_cr("----------"); } gclog_or_tty->print_cr("Missing rem set entry:"); gclog_or_tty->print_cr("Field "PTR_FORMAT " of obj "PTR_FORMAT ", in region %d ["PTR_FORMAT ", "PTR_FORMAT"),", p, (void*) _containing_obj, from->hrs_index(), from->bottom(), from->end()); _containing_obj->print_on(gclog_or_tty); gclog_or_tty->print_cr("points to obj "PTR_FORMAT " in region %d ["PTR_FORMAT ", "PTR_FORMAT").", (void*) obj, to->hrs_index(), to->bottom(), to->end()); obj->print_on(gclog_or_tty); gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.", cv_obj, cv_field); gclog_or_tty->print_cr("----------"); _failures = true; if (!failed) _n_failures++; } } } } } }; template HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h, HeapRegion* hr, HeapWord* cur, HeapWord* top) { oop cur_oop = oop(cur); int oop_size = cur_oop->size(); HeapWord* next_obj = cur + oop_size; while (next_obj < top) { // Keep filtering the remembered set. if (!g1h->is_obj_dead(cur_oop, hr)) { // Bottom lies entirely below top, so we can call the // non-memRegion version of oop_iterate below. #ifndef PRODUCT if (G1VerifyMarkingInEvac) { VerifyLiveClosure vl_cl(g1h); cur_oop->oop_iterate(&vl_cl); } #endif cur_oop->oop_iterate(cl); } cur = next_obj; cur_oop = oop(cur); oop_size = cur_oop->size(); next_obj = cur + oop_size; } return cur; } void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr, HeapWord* bottom, HeapWord* top, OopClosure* cl) { G1CollectedHeap* g1h = _g1; int oop_size; OopClosure* cl2 = cl; FilterIntoCSClosure intoCSFilt(this, g1h, cl); FilterOutOfRegionClosure outOfRegionFilt(_hr, cl); switch (_fk) { case IntoCSFilterKind: cl2 = &intoCSFilt; break; case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break; } // Start filtering what we add to the remembered set. If the object is // not considered dead, either because it is marked (in the mark bitmap) // or it was allocated after marking finished, then we add it. Otherwise // we can safely ignore the object. if (!g1h->is_obj_dead(oop(bottom), _hr)) { #ifndef PRODUCT if (G1VerifyMarkingInEvac) { VerifyLiveClosure vl_cl(g1h); oop(bottom)->oop_iterate(&vl_cl, mr); } #endif oop_size = oop(bottom)->oop_iterate(cl2, mr); } else { oop_size = oop(bottom)->size(); } bottom += oop_size; if (bottom < top) { // We replicate the loop below for several kinds of possible filters. switch (_fk) { case NoFilterKind: bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top); break; case IntoCSFilterKind: { FilterIntoCSClosure filt(this, g1h, cl); bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); break; } case OutOfRegionFilterKind: { FilterOutOfRegionClosure filt(_hr, cl); bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); break; } default: ShouldNotReachHere(); } // Last object. Need to do dead-obj filtering here too. if (!g1h->is_obj_dead(oop(bottom), _hr)) { #ifndef PRODUCT if (G1VerifyMarkingInEvac) { VerifyLiveClosure vl_cl(g1h); oop(bottom)->oop_iterate(&vl_cl, mr); } #endif oop(bottom)->oop_iterate(cl2, mr); } } } void HeapRegion::reset_after_compaction() { G1OffsetTableContigSpace::reset_after_compaction(); // After a compaction the mark bitmap is invalid, so we must // treat all objects as being inside the unmarked area. zero_marked_bytes(); init_top_at_mark_start(); } DirtyCardToOopClosure* HeapRegion::new_dcto_closure(OopClosure* cl, CardTableModRefBS::PrecisionStyle precision, HeapRegionDCTOC::FilterKind fk) { return new HeapRegionDCTOC(G1CollectedHeap::heap(), this, cl, precision, fk); } void HeapRegion::hr_clear(bool par, bool clear_space) { _humongous = false; _humongous_start = false; _humongous_start_region = NULL; _in_collection_set = false; _is_gc_alloc_region = false; // Age stuff (if parallel, this will be done separately, since it needs // to be sequential). G1CollectedHeap* g1h = G1CollectedHeap::heap(); set_young_index_in_cset(-1); uninstall_surv_rate_group(); set_young_type(NotYoung); // In case it had been the start of a humongous sequence, reset its end. set_end(_orig_end); if (!par) { // If this is parallel, this will be done later. HeapRegionRemSet* hrrs = rem_set(); if (hrrs != NULL) hrrs->clear(); _claimed = 0; } zero_marked_bytes(); set_sort_index(-1); if ((uintptr_t)bottom() >= (uintptr_t)g1h->popular_object_boundary()) set_popular(false); _offsets.resize(HeapRegion::GrainWords); init_top_at_mark_start(); if (clear_space) clear(); } // void HeapRegion::calc_gc_efficiency() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); _gc_efficiency = (double) garbage_bytes() / g1h->predict_region_elapsed_time_ms(this, false); } // void HeapRegion::set_startsHumongous() { _humongous_start = true; _humongous = true; _humongous_start_region = this; assert(end() == _orig_end, "Should be normal before alloc."); } bool HeapRegion::claimHeapRegion(jint claimValue) { jint current = _claimed; if (current != claimValue) { jint res = Atomic::cmpxchg(claimValue, &_claimed, current); if (res == current) { return true; } } return false; } HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) { HeapWord* low = addr; HeapWord* high = end(); while (low < high) { size_t diff = pointer_delta(high, low); // Must add one below to bias toward the high amount. Otherwise, if // "high" were at the desired value, and "low" were one less, we // would not converge on "high". This is not symmetric, because // we set "high" to a block start, which might be the right one, // which we don't do for "low". HeapWord* middle = low + (diff+1)/2; if (middle == high) return high; HeapWord* mid_bs = block_start_careful(middle); if (mid_bs < addr) { low = middle; } else { high = mid_bs; } } assert(low == high && low >= addr, "Didn't work."); return low; } void HeapRegion::set_next_on_unclean_list(HeapRegion* r) { assert(r == NULL || r->is_on_unclean_list(), "Malformed unclean list."); _next_in_special_set = r; } void HeapRegion::set_on_unclean_list(bool b) { _is_on_unclean_list = b; } void HeapRegion::initialize(MemRegion mr, bool clear_space) { G1OffsetTableContigSpace::initialize(mr, false); hr_clear(false/*par*/, clear_space); } #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away #pragma warning( disable:4355 ) // 'this' : used in base member initializer list #endif // _MSC_VER HeapRegion:: HeapRegion(G1BlockOffsetSharedArray* sharedOffsetArray, MemRegion mr, bool is_zeroed) : G1OffsetTableContigSpace(sharedOffsetArray, mr, is_zeroed), _next_fk(HeapRegionDCTOC::NoFilterKind), _hrs_index(-1), _humongous(false), _humongous_start(false), _humongous_start_region(NULL), _in_collection_set(false), _is_gc_alloc_region(false), _is_on_free_list(false), _is_on_unclean_list(false), _next_in_special_set(NULL), _orig_end(NULL), _claimed(0), _evacuation_failed(false), _prev_marked_bytes(0), _next_marked_bytes(0), _sort_index(-1), _popularity(NotPopular), _young_type(NotYoung), _next_young_region(NULL), _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1), _rem_set(NULL), _zfs(NotZeroFilled) { _orig_end = mr.end(); // Note that initialize() will set the start of the unmarked area of the // region. this->initialize(mr, !is_zeroed); _rem_set = new HeapRegionRemSet(sharedOffsetArray, this); assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant."); // In case the region is allocated during a pause, note the top. // We haven't done any counting on a brand new region. _top_at_conc_mark_count = bottom(); } class NextCompactionHeapRegionClosure: public HeapRegionClosure { const HeapRegion* _target; bool _target_seen; HeapRegion* _last; CompactibleSpace* _res; public: NextCompactionHeapRegionClosure(const HeapRegion* target) : _target(target), _target_seen(false), _res(NULL) {} bool doHeapRegion(HeapRegion* cur) { if (_target_seen) { if (!cur->isHumongous()) { _res = cur; return true; } } else if (cur == _target) { _target_seen = true; } return false; } CompactibleSpace* result() { return _res; } }; CompactibleSpace* HeapRegion::next_compaction_space() const { G1CollectedHeap* g1h = G1CollectedHeap::heap(); // cast away const-ness HeapRegion* r = (HeapRegion*) this; NextCompactionHeapRegionClosure blk(r); g1h->heap_region_iterate_from(r, &blk); return blk.result(); } void HeapRegion::set_continuesHumongous(HeapRegion* start) { // The order is important here. start->add_continuingHumongousRegion(this); _humongous = true; _humongous_start = false; _humongous_start_region = start; } void HeapRegion::add_continuingHumongousRegion(HeapRegion* cont) { // Must join the blocks of the current H region seq with the block of the // added region. offsets()->join_blocks(bottom(), cont->bottom()); arrayOop obj = (arrayOop)(bottom()); obj->set_length((int) (obj->length() + cont->capacity()/jintSize)); set_end(cont->end()); set_top(cont->end()); } void HeapRegion::save_marks() { set_saved_mark(); } void HeapRegion::oops_in_mr_iterate(MemRegion mr, OopClosure* cl) { HeapWord* p = mr.start(); HeapWord* e = mr.end(); oop obj; while (p < e) { obj = oop(p); p += obj->oop_iterate(cl); } assert(p == e, "bad memregion: doesn't end on obj boundary"); } #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \ } SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN) void HeapRegion::oop_before_save_marks_iterate(OopClosure* cl) { oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl); } #ifdef DEBUG HeapWord* HeapRegion::allocate(size_t size) { jint state = zero_fill_state(); assert(!G1CollectedHeap::heap()->allocs_are_zero_filled() || zero_fill_is_allocated(), "When ZF is on, only alloc in ZF'd regions"); return G1OffsetTableContigSpace::allocate(size); } #endif void HeapRegion::set_zero_fill_state_work(ZeroFillState zfs) { assert(top() == bottom() || zfs == Allocated, "Region must be empty, or we must be setting it to allocated."); assert(ZF_mon->owned_by_self() || Universe::heap()->is_gc_active(), "Must hold the lock or be a full GC to modify."); _zfs = zfs; } void HeapRegion::set_zero_fill_complete() { set_zero_fill_state_work(ZeroFilled); if (ZF_mon->owned_by_self()) { ZF_mon->notify_all(); } } void HeapRegion::ensure_zero_filled() { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); ensure_zero_filled_locked(); } void HeapRegion::ensure_zero_filled_locked() { assert(ZF_mon->owned_by_self(), "Precondition"); bool should_ignore_zf = SafepointSynchronize::is_at_safepoint(); assert(should_ignore_zf || Heap_lock->is_locked(), "Either we're in a GC or we're allocating a region."); switch (zero_fill_state()) { case HeapRegion::NotZeroFilled: set_zero_fill_in_progress(Thread::current()); { ZF_mon->unlock(); Copy::fill_to_words(bottom(), capacity()/HeapWordSize); ZF_mon->lock_without_safepoint_check(); } // A trap. guarantee(zero_fill_state() == HeapRegion::ZeroFilling && zero_filler() == Thread::current(), "AHA! Tell Dave D if you see this..."); set_zero_fill_complete(); // gclog_or_tty->print_cr("Did sync ZF."); ConcurrentZFThread::note_sync_zfs(); break; case HeapRegion::ZeroFilling: if (should_ignore_zf) { // We can "break" the lock and take over the work. Copy::fill_to_words(bottom(), capacity()/HeapWordSize); set_zero_fill_complete(); ConcurrentZFThread::note_sync_zfs(); break; } else { ConcurrentZFThread::wait_for_ZF_completed(this); } case HeapRegion::ZeroFilled: // Nothing to do. break; case HeapRegion::Allocated: guarantee(false, "Should not call on allocated regions."); } assert(zero_fill_state() == HeapRegion::ZeroFilled, "Post"); } HeapWord* HeapRegion::object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl) { G1CollectedHeap* g1h = G1CollectedHeap::heap(); // We used to use "block_start_careful" here. But we're actually happy // to update the BOT while we do this... HeapWord* cur = block_start(mr.start()); mr = mr.intersection(used_region()); if (mr.is_empty()) return NULL; // Otherwise, find the obj that extends onto mr.start(). assert(cur <= mr.start() && (oop(cur)->klass() == NULL || cur + oop(cur)->size() > mr.start()), "postcondition of block_start"); oop obj; while (cur < mr.end()) { obj = oop(cur); if (obj->klass() == NULL) { // Ran into an unparseable point. return cur; } else if (!g1h->is_obj_dead(obj)) { cl->do_object(obj); } if (cl->abort()) return cur; // The check above must occur before the operation below, since an // abort might invalidate the "size" operation. cur += obj->size(); } return NULL; } HeapWord* HeapRegion:: oops_on_card_seq_iterate_careful(MemRegion mr, FilterOutOfRegionClosure* cl) { G1CollectedHeap* g1h = G1CollectedHeap::heap(); // If we're within a stop-world GC, then we might look at a card in a // GC alloc region that extends onto a GC LAB, which may not be // parseable. Stop such at the "saved_mark" of the region. if (G1CollectedHeap::heap()->is_gc_active()) { mr = mr.intersection(used_region_at_save_marks()); } else { mr = mr.intersection(used_region()); } if (mr.is_empty()) return NULL; // Otherwise, find the obj that extends onto mr.start(). // We used to use "block_start_careful" here. But we're actually happy // to update the BOT while we do this... HeapWord* cur = block_start(mr.start()); assert(cur <= mr.start(), "Postcondition"); while (cur <= mr.start()) { if (oop(cur)->klass() == NULL) { // Ran into an unparseable point. return cur; } // Otherwise... int sz = oop(cur)->size(); if (cur + sz > mr.start()) break; // Otherwise, go on. cur = cur + sz; } oop obj; obj = oop(cur); // If we finish this loop... assert(cur <= mr.start() && obj->klass() != NULL && cur + obj->size() > mr.start(), "Loop postcondition"); if (!g1h->is_obj_dead(obj)) { obj->oop_iterate(cl, mr); } HeapWord* next; while (cur < mr.end()) { obj = oop(cur); if (obj->klass() == NULL) { // Ran into an unparseable point. return cur; }; // Otherwise: next = (cur + obj->size()); if (!g1h->is_obj_dead(obj)) { if (next < mr.end()) { obj->oop_iterate(cl); } else { // this obj spans the boundary. If it's an array, stop at the // boundary. if (obj->is_objArray()) { obj->oop_iterate(cl, mr); } else { obj->oop_iterate(cl); } } } cur = next; } return NULL; } void HeapRegion::print() const { print_on(gclog_or_tty); } void HeapRegion::print_on(outputStream* st) const { if (isHumongous()) { if (startsHumongous()) st->print(" HS"); else st->print(" HC"); } else { st->print(" "); } if (in_collection_set()) st->print(" CS"); else if (is_gc_alloc_region()) st->print(" A "); else st->print(" "); if (is_young()) st->print(is_scan_only() ? " SO" : (is_survivor() ? " SU" : " Y ")); else st->print(" "); if (is_empty()) st->print(" F"); else st->print(" "); st->print(" %d", _gc_time_stamp); G1OffsetTableContigSpace::print_on(st); } #define OBJ_SAMPLE_INTERVAL 0 #define BLOCK_SAMPLE_INTERVAL 100 // This really ought to be commoned up into OffsetTableContigSpace somehow. // We would need a mechanism to make that code skip dead objects. void HeapRegion::verify(bool allow_dirty) const { G1CollectedHeap* g1 = G1CollectedHeap::heap(); HeapWord* p = bottom(); HeapWord* prev_p = NULL; int objs = 0; int blocks = 0; VerifyLiveClosure vl_cl(g1); while (p < top()) { size_t size = oop(p)->size(); if (blocks == BLOCK_SAMPLE_INTERVAL) { guarantee(p == block_start_const(p + (size/2)), "check offset computation"); blocks = 0; } else { blocks++; } if (objs == OBJ_SAMPLE_INTERVAL) { oop obj = oop(p); if (!g1->is_obj_dead(obj, this)) { obj->verify(); vl_cl.set_containing_obj(obj); obj->oop_iterate(&vl_cl); if (G1MaxVerifyFailures >= 0 && vl_cl.n_failures() >= G1MaxVerifyFailures) break; } objs = 0; } else { objs++; } prev_p = p; p += size; } HeapWord* rend = end(); HeapWord* rtop = top(); if (rtop < rend) { guarantee(block_start_const(rtop + (rend - rtop) / 2) == rtop, "check offset computation"); } if (vl_cl.failures()) { gclog_or_tty->print_cr("Heap:"); G1CollectedHeap::heap()->print(); gclog_or_tty->print_cr(""); } if (G1VerifyConcMark && G1VerifyConcMarkPrintReachable && vl_cl.failures()) { g1->concurrent_mark()->print_prev_bitmap_reachable(); } guarantee(!vl_cl.failures(), "should not have had any failures"); guarantee(p == top(), "end of last object must match end of space"); } // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go // away eventually. void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space) { // false ==> we'll do the clearing if there's clearing to be done. ContiguousSpace::initialize(mr, false); _offsets.zero_bottom_entry(); _offsets.initialize_threshold(); if (clear_space) clear(); } void G1OffsetTableContigSpace::clear() { ContiguousSpace::clear(); _offsets.zero_bottom_entry(); _offsets.initialize_threshold(); } void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { Space::set_bottom(new_bottom); _offsets.set_bottom(new_bottom); } void G1OffsetTableContigSpace::set_end(HeapWord* new_end) { Space::set_end(new_end); _offsets.resize(new_end - bottom()); } void G1OffsetTableContigSpace::print() const { print_short(); gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", bottom(), top(), _offsets.threshold(), end()); } HeapWord* G1OffsetTableContigSpace::initialize_threshold() { return _offsets.initialize_threshold(); } HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) { _offsets.alloc_block(start, end); return _offsets.threshold(); } HeapWord* G1OffsetTableContigSpace::saved_mark_word() const { G1CollectedHeap* g1h = G1CollectedHeap::heap(); assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" ); if (_gc_time_stamp < g1h->get_gc_time_stamp()) return top(); else return ContiguousSpace::saved_mark_word(); } void G1OffsetTableContigSpace::set_saved_mark() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp(); if (_gc_time_stamp < curr_gc_time_stamp) { // The order of these is important, as another thread might be // about to start scanning this region. If it does so after // set_saved_mark and before _gc_time_stamp = ..., then the latter // will be false, and it will pick up top() as the high water mark // of region. If it does so after _gc_time_stamp = ..., then it // will pick up the right saved_mark_word() as the high water mark // of the region. Either way, the behaviour will be correct. ContiguousSpace::set_saved_mark(); OrderAccess::release_store_ptr((volatile intptr_t*) &_gc_time_stamp, (intptr_t) curr_gc_time_stamp); } } G1OffsetTableContigSpace:: G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray, MemRegion mr, bool is_zeroed) : _offsets(sharedOffsetArray, mr), _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true), _gc_time_stamp(0) { _offsets.set_space(this); initialize(mr, !is_zeroed); } size_t RegionList::length() { size_t len = 0; HeapRegion* cur = hd(); DEBUG_ONLY(HeapRegion* last = NULL); while (cur != NULL) { len++; DEBUG_ONLY(last = cur); cur = get_next(cur); } assert(last == tl(), "Invariant"); return len; } void RegionList::insert_before_head(HeapRegion* r) { assert(well_formed(), "Inv"); set_next(r, hd()); _hd = r; _sz++; if (tl() == NULL) _tl = r; assert(well_formed(), "Inv"); } void RegionList::prepend_list(RegionList* new_list) { assert(well_formed(), "Precondition"); assert(new_list->well_formed(), "Precondition"); HeapRegion* new_tl = new_list->tl(); if (new_tl != NULL) { set_next(new_tl, hd()); _hd = new_list->hd(); _sz += new_list->sz(); if (tl() == NULL) _tl = new_list->tl(); } else { assert(new_list->hd() == NULL && new_list->sz() == 0, "Inv"); } assert(well_formed(), "Inv"); } void RegionList::delete_after(HeapRegion* r) { assert(well_formed(), "Precondition"); HeapRegion* next = get_next(r); assert(r != NULL, "Precondition"); HeapRegion* next_tl = get_next(next); set_next(r, next_tl); dec_sz(); if (next == tl()) { assert(next_tl == NULL, "Inv"); _tl = r; } assert(well_formed(), "Inv"); } HeapRegion* RegionList::pop() { assert(well_formed(), "Inv"); HeapRegion* res = hd(); if (res != NULL) { _hd = get_next(res); _sz--; set_next(res, NULL); if (sz() == 0) _tl = NULL; } assert(well_formed(), "Inv"); return res; }