ysr@777: /*
xdono@1279:  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
ysr@777:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ysr@777:  *
ysr@777:  * This code is free software; you can redistribute it and/or modify it
ysr@777:  * under the terms of the GNU General Public License version 2 only, as
ysr@777:  * published by the Free Software Foundation.
ysr@777:  *
ysr@777:  * This code is distributed in the hope that it will be useful, but WITHOUT
ysr@777:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ysr@777:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ysr@777:  * version 2 for more details (a copy is included in the LICENSE file that
ysr@777:  * accompanied this code).
ysr@777:  *
ysr@777:  * You should have received a copy of the GNU General Public License version
ysr@777:  * 2 along with this work; if not, write to the Free Software Foundation,
ysr@777:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ysr@777:  *
ysr@777:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
ysr@777:  * CA 95054 USA or visit www.sun.com if you need additional information or
ysr@777:  * have any questions.
ysr@777:  *
ysr@777:  */
ysr@777: 
ysr@777: #include "incls/_precompiled.incl"
ysr@777: #include "incls/_g1MarkSweep.cpp.incl"
ysr@777: 
ysr@777: class HeapRegion;
ysr@777: 
ysr@777: void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
ysr@777:                                       bool clear_all_softrefs) {
ysr@777:   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
ysr@777: 
ysr@777:   // hook up weak ref data so it can be used during Mark-Sweep
ysr@777:   assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
ysr@888:   assert(rp != NULL, "should be non-NULL");
ysr@777:   GenMarkSweep::_ref_processor = rp;
ysr@892:   rp->setup_policy(clear_all_softrefs);
ysr@777: 
ysr@777:   // When collecting the permanent generation methodOops may be moving,
ysr@777:   // so we either have to flush all bcp data or convert it into bci.
ysr@777:   CodeCache::gc_prologue();
ysr@777:   Threads::gc_prologue();
ysr@777: 
ysr@777:   // Increment the invocation count for the permanent generation, since it is
ysr@777:   // implicitly collected whenever we do a full mark sweep collection.
ysr@777:   SharedHeap* sh = SharedHeap::heap();
ysr@777:   sh->perm_gen()->stat_record()->invocations++;
ysr@777: 
ysr@777:   bool marked_for_unloading = false;
ysr@777: 
ysr@777:   allocate_stacks();
ysr@777: 
iveresov@793:   // We should save the marks of the currently locked biased monitors.
iveresov@793:   // The marking doesn't preserve the marks of biased objects.
iveresov@793:   BiasedLocking::preserve_marks();
iveresov@793: 
ysr@777:   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
ysr@777: 
johnc@1186:   if (VerifyDuringGC) {
ysr@777:       G1CollectedHeap* g1h = G1CollectedHeap::heap();
ysr@777:       g1h->checkConcurrentMark();
ysr@777:   }
ysr@777: 
ysr@777:   mark_sweep_phase2();
ysr@777: 
ysr@777:   // Don't add any more derived pointers during phase3
ysr@777:   COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
ysr@777: 
ysr@777:   mark_sweep_phase3();
ysr@777: 
ysr@777:   mark_sweep_phase4();
ysr@777: 
ysr@777:   GenMarkSweep::restore_marks();
iveresov@793:   BiasedLocking::restore_marks();
ysr@777:   GenMarkSweep::deallocate_stacks();
ysr@777: 
ysr@777:   // We must invalidate the perm-gen rs, so that it gets rebuilt.
ysr@777:   GenRemSet* rs = sh->rem_set();
ysr@777:   rs->invalidate(sh->perm_gen()->used_region(), true /*whole_heap*/);
ysr@777: 
ysr@777:   // "free at last gc" is calculated from these.
ysr@777:   // CHF: cheating for now!!!
ysr@777:   //  Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
ysr@777:   //  Universe::set_heap_used_at_last_gc(Universe::heap()->used());
ysr@777: 
ysr@777:   Threads::gc_epilogue();
ysr@777:   CodeCache::gc_epilogue();
ysr@777: 
ysr@777:   // refs processing: clean slate
ysr@777:   GenMarkSweep::_ref_processor = NULL;
ysr@777: }
ysr@777: 
ysr@777: 
ysr@777: void G1MarkSweep::allocate_stacks() {
ysr@777:   GenMarkSweep::_preserved_count_max = 0;
ysr@777:   GenMarkSweep::_preserved_marks = NULL;
ysr@777:   GenMarkSweep::_preserved_count = 0;
ysr@777:   GenMarkSweep::_preserved_mark_stack = NULL;
ysr@777:   GenMarkSweep::_preserved_oop_stack = NULL;
ysr@777: 
ysr@777:   GenMarkSweep::_marking_stack =
ysr@777:     new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
ysr@777: 
ysr@1376:   int size = SystemDictionary::number_of_classes() * 2;
ysr@777:   GenMarkSweep::_revisit_klass_stack =
ysr@1376:     new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
ysr@1376:   // (#klass/k)^2 for k ~ 10 appears a better fit, but this will have to do
ysr@1376:   // for now until we have a chance to work out a more optimal setting.
ysr@1376:   GenMarkSweep::_revisit_mdo_stack =
ysr@1376:     new (ResourceObj::C_HEAP) GrowableArray<DataLayout*>(size*2, true);
ysr@1376: 
ysr@777: }
ysr@777: 
ysr@777: void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
ysr@777:                                     bool clear_all_softrefs) {
ysr@777:   // Recursively traverse all live objects and mark them
ysr@777:   EventMark m("1 mark object");
ysr@777:   TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
ysr@777:   GenMarkSweep::trace(" 1");
ysr@777: 
ysr@777:   SharedHeap* sh = SharedHeap::heap();
ysr@777: 
jrose@1424:   sh->process_strong_roots(true,  // activeate StrongRootsScope
jrose@1424:                            true,  // Collecting permanent generation.
ysr@777:                            SharedHeap::SO_SystemClasses,
ysr@777:                            &GenMarkSweep::follow_root_closure,
jrose@1424:                            &GenMarkSweep::follow_code_root_closure,
ysr@777:                            &GenMarkSweep::follow_root_closure);
ysr@777: 
ysr@777:   // Process reference objects found during marking
ysr@888:   ReferenceProcessor* rp = GenMarkSweep::ref_processor();
ysr@892:   rp->setup_policy(clear_all_softrefs);
ysr@888:   rp->process_discovered_references(&GenMarkSweep::is_alive,
ysr@888:                                     &GenMarkSweep::keep_alive,
ysr@888:                                     &GenMarkSweep::follow_stack_closure,
ysr@888:                                     NULL);
ysr@777: 
ysr@777:   // Follow system dictionary roots and unload classes
ysr@777:   bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
ysr@777:   assert(GenMarkSweep::_marking_stack->is_empty(),
ysr@777:          "stack should be empty by now");
ysr@777: 
ysr@777:   // Follow code cache roots (has to be done after system dictionary,
ysr@777:   // assumes all live klasses are marked)
ysr@777:   CodeCache::do_unloading(&GenMarkSweep::is_alive,
ysr@777:                                    &GenMarkSweep::keep_alive,
ysr@777:                                    purged_class);
ysr@1376:   GenMarkSweep::follow_stack();
ysr@777: 
ysr@777:   // Update subklass/sibling/implementor links of live klasses
ysr@777:   GenMarkSweep::follow_weak_klass_links();
ysr@777:   assert(GenMarkSweep::_marking_stack->is_empty(),
ysr@777:          "stack should be empty by now");
ysr@777: 
ysr@1376:   // Visit memoized MDO's and clear any unmarked weak refs
ysr@1376:   GenMarkSweep::follow_mdo_weak_refs();
ysr@1376:   assert(GenMarkSweep::_marking_stack->is_empty(), "just drained");
ysr@1376: 
ysr@1376: 
ysr@777:   // Visit symbol and interned string tables and delete unmarked oops
ysr@777:   SymbolTable::unlink(&GenMarkSweep::is_alive);
ysr@777:   StringTable::unlink(&GenMarkSweep::is_alive);
ysr@777: 
ysr@777:   assert(GenMarkSweep::_marking_stack->is_empty(),
ysr@777:          "stack should be empty by now");
ysr@777: }
ysr@777: 
ysr@777: class G1PrepareCompactClosure: public HeapRegionClosure {
ysr@777:   ModRefBarrierSet* _mrbs;
ysr@777:   CompactPoint _cp;
ysr@777: 
ysr@777:   void free_humongous_region(HeapRegion* hr) {
ysr@777:     HeapWord* bot = hr->bottom();
ysr@777:     HeapWord* end = hr->end();
ysr@777:     assert(hr->startsHumongous(),
ysr@777:            "Only the start of a humongous region should be freed.");
ysr@777:     G1CollectedHeap::heap()->free_region(hr);
ysr@777:     hr->prepare_for_compaction(&_cp);
ysr@777:     // Also clear the part of the card table that will be unused after
ysr@777:     // compaction.
ysr@777:     _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
ysr@777:   }
ysr@777: 
ysr@777: public:
apetrusenko@1112:   G1PrepareCompactClosure(CompactibleSpace* cs) :
ysr@777:     _cp(NULL, cs, cs->initialize_threshold()),
apetrusenko@1112:     _mrbs(G1CollectedHeap::heap()->mr_bs())
ysr@777:   {}
ysr@777:   bool doHeapRegion(HeapRegion* hr) {
ysr@777:     if (hr->isHumongous()) {
ysr@777:       if (hr->startsHumongous()) {
ysr@777:         oop obj = oop(hr->bottom());
ysr@777:         if (obj->is_gc_marked()) {
ysr@777:           obj->forward_to(obj);
ysr@777:         } else  {
ysr@777:           free_humongous_region(hr);
ysr@777:         }
ysr@777:       } else {
ysr@777:         assert(hr->continuesHumongous(), "Invalid humongous.");
ysr@777:       }
ysr@777:     } else {
ysr@777:       hr->prepare_for_compaction(&_cp);
ysr@777:       // Also clear the part of the card table that will be unused after
ysr@777:       // compaction.
ysr@777:       _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
ysr@777:     }
ysr@777:     return false;
ysr@777:   }
ysr@777: };
apetrusenko@1112: 
apetrusenko@1112: // Finds the first HeapRegion.
ysr@777: class FindFirstRegionClosure: public HeapRegionClosure {
ysr@777:   HeapRegion* _a_region;
ysr@777: public:
apetrusenko@1112:   FindFirstRegionClosure() : _a_region(NULL) {}
ysr@777:   bool doHeapRegion(HeapRegion* r) {
apetrusenko@1112:     _a_region = r;
apetrusenko@1112:     return true;
ysr@777:   }
ysr@777:   HeapRegion* result() { return _a_region; }
ysr@777: };
ysr@777: 
ysr@777: void G1MarkSweep::mark_sweep_phase2() {
ysr@777:   // Now all live objects are marked, compute the new object addresses.
ysr@777: 
ysr@777:   // It is imperative that we traverse perm_gen LAST. If dead space is
ysr@777:   // allowed a range of dead object may get overwritten by a dead int
ysr@777:   // array. If perm_gen is not traversed last a klassOop may get
ysr@777:   // overwritten. This is fine since it is dead, but if the class has dead
ysr@777:   // instances we have to skip them, and in order to find their size we
ysr@777:   // need the klassOop!
ysr@777:   //
ysr@777:   // It is not required that we traverse spaces in the same order in
ysr@777:   // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
ysr@777:   // tracking expects us to do so. See comment under phase4.
ysr@777: 
ysr@777:   G1CollectedHeap* g1h = G1CollectedHeap::heap();
ysr@777:   Generation* pg = g1h->perm_gen();
ysr@777: 
ysr@777:   EventMark m("2 compute new addresses");
ysr@777:   TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
ysr@777:   GenMarkSweep::trace("2");
ysr@777: 
apetrusenko@1112:   FindFirstRegionClosure cl;
ysr@777:   g1h->heap_region_iterate(&cl);
ysr@777:   HeapRegion *r = cl.result();
ysr@777:   CompactibleSpace* sp = r;
ysr@777:   if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) {
ysr@777:     sp = r->next_compaction_space();
ysr@777:   }
ysr@777: 
apetrusenko@1112:   G1PrepareCompactClosure blk(sp);
ysr@777:   g1h->heap_region_iterate(&blk);
ysr@777: 
ysr@777:   CompactPoint perm_cp(pg, NULL, NULL);
ysr@777:   pg->prepare_for_compaction(&perm_cp);
ysr@777: }
ysr@777: 
ysr@777: class G1AdjustPointersClosure: public HeapRegionClosure {
ysr@777:  public:
ysr@777:   bool doHeapRegion(HeapRegion* r) {
ysr@777:     if (r->isHumongous()) {
ysr@777:       if (r->startsHumongous()) {
ysr@777:         // We must adjust the pointers on the single H object.
ysr@777:         oop obj = oop(r->bottom());
ysr@777:         debug_only(GenMarkSweep::track_interior_pointers(obj));
ysr@777:         // point all the oops to the new location
ysr@777:         obj->adjust_pointers();
ysr@777:         debug_only(GenMarkSweep::check_interior_pointers());
ysr@777:       }
ysr@777:     } else {
ysr@777:       // This really ought to be "as_CompactibleSpace"...
ysr@777:       r->adjust_pointers();
ysr@777:     }
ysr@777:     return false;
ysr@777:   }
ysr@777: };
ysr@777: 
ysr@777: void G1MarkSweep::mark_sweep_phase3() {
ysr@777:   G1CollectedHeap* g1h = G1CollectedHeap::heap();
ysr@777:   Generation* pg = g1h->perm_gen();
ysr@777: 
ysr@777:   // Adjust the pointers to reflect the new locations
ysr@777:   EventMark m("3 adjust pointers");
ysr@777:   TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
ysr@777:   GenMarkSweep::trace("3");
ysr@777: 
ysr@777:   SharedHeap* sh = SharedHeap::heap();
ysr@777: 
jrose@1424:   sh->process_strong_roots(true,  // activate StrongRootsScope
jrose@1424:                            true,  // Collecting permanent generation.
ysr@777:                            SharedHeap::SO_AllClasses,
ysr@777:                            &GenMarkSweep::adjust_root_pointer_closure,
jrose@1424:                            NULL,  // do not touch code cache here
ysr@777:                            &GenMarkSweep::adjust_pointer_closure);
ysr@777: 
ysr@777:   g1h->ref_processor()->weak_oops_do(&GenMarkSweep::adjust_root_pointer_closure);
ysr@777: 
ysr@777:   // Now adjust pointers in remaining weak roots.  (All of which should
ysr@777:   // have been cleared if they pointed to non-surviving objects.)
ysr@777:   g1h->g1_process_weak_roots(&GenMarkSweep::adjust_root_pointer_closure,
ysr@777:                              &GenMarkSweep::adjust_pointer_closure);
ysr@777: 
ysr@777:   GenMarkSweep::adjust_marks();
ysr@777: 
ysr@777:   G1AdjustPointersClosure blk;
ysr@777:   g1h->heap_region_iterate(&blk);
ysr@777:   pg->adjust_pointers();
ysr@777: }
ysr@777: 
ysr@777: class G1SpaceCompactClosure: public HeapRegionClosure {
ysr@777: public:
ysr@777:   G1SpaceCompactClosure() {}
ysr@777: 
ysr@777:   bool doHeapRegion(HeapRegion* hr) {
ysr@777:     if (hr->isHumongous()) {
ysr@777:       if (hr->startsHumongous()) {
ysr@777:         oop obj = oop(hr->bottom());
ysr@777:         if (obj->is_gc_marked()) {
ysr@777:           obj->init_mark();
ysr@777:         } else {
ysr@777:           assert(hr->is_empty(), "Should have been cleared in phase 2.");
ysr@777:         }
ysr@777:         hr->reset_during_compaction();
ysr@777:       }
ysr@777:     } else {
ysr@777:       hr->compact();
ysr@777:     }
ysr@777:     return false;
ysr@777:   }
ysr@777: };
ysr@777: 
ysr@777: void G1MarkSweep::mark_sweep_phase4() {
ysr@777:   // All pointers are now adjusted, move objects accordingly
ysr@777: 
ysr@777:   // It is imperative that we traverse perm_gen first in phase4. All
ysr@777:   // classes must be allocated earlier than their instances, and traversing
ysr@777:   // perm_gen first makes sure that all klassOops have moved to their new
ysr@777:   // location before any instance does a dispatch through it's klass!
ysr@777: 
ysr@777:   // The ValidateMarkSweep live oops tracking expects us to traverse spaces
ysr@777:   // in the same order in phase2, phase3 and phase4. We don't quite do that
ysr@777:   // here (perm_gen first rather than last), so we tell the validate code
ysr@777:   // to use a higher index (saved from phase2) when verifying perm_gen.
ysr@777:   G1CollectedHeap* g1h = G1CollectedHeap::heap();
ysr@777:   Generation* pg = g1h->perm_gen();
ysr@777: 
ysr@777:   EventMark m("4 compact heap");
ysr@777:   TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
ysr@777:   GenMarkSweep::trace("4");
ysr@777: 
ysr@777:   pg->compact();
ysr@777: 
ysr@777:   G1SpaceCompactClosure blk;
ysr@777:   g1h->heap_region_iterate(&blk);
ysr@777: 
ysr@777: }
ysr@777: 
ysr@777: // Local Variables: ***
ysr@777: // c-indentation-style: gnu ***
ysr@777: // End: ***