#include "precompiled.hpp"

#include "classfile/javaClasses.hpp"

#include "classfile/symbolTable.hpp"

#include "classfile/systemDictionary.hpp"

#include "classfile/vmSymbols.hpp"

#include "code/codeCache.hpp"

#include "code/icBuffer.hpp"

#include "gc_implementation/shared/gcHeapSummary.hpp"

#include "gc_implementation/shared/gcTimer.hpp"

#include "gc_implementation/shared/gcTrace.hpp"

#include "gc_implementation/shared/gcTraceTime.hpp"

#include "gc_interface/collectedHeap.inline.hpp"

#include "memory/genCollectedHeap.hpp"

#include "memory/genMarkSweep.hpp"

#include "memory/genOopClosures.inline.hpp"

#include "memory/generation.inline.hpp"

#include "memory/modRefBarrierSet.hpp"

#include "memory/referencePolicy.hpp"

#include "memory/space.hpp"

#include "oops/instanceRefKlass.hpp"

#include "oops/oop.inline.hpp"

#include "prims/jvmtiExport.hpp"

#include "runtime/fprofiler.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/synchronizer.hpp"

#include "runtime/vmThread.hpp"

#include "utilities/copy.hpp"

#include "utilities/events.hpp"

#ifdef TARGET_OS_FAMILY_linux

# include "thread_linux.inline.hpp"

#endif

#ifdef TARGET_OS_FAMILY_solaris

# include "thread_solaris.inline.hpp"

#endif

#ifdef TARGET_OS_FAMILY_windows

# include "thread_windows.inline.hpp"

#endif

#ifdef TARGET_OS_FAMILY_bsd

# include "thread_bsd.inline.hpp"

#endif

void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,

bool clear_all_softrefs) {

assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");

GenCollectedHeap* gch = GenCollectedHeap::heap();

#ifdef ASSERT

if (gch->collector_policy()->should_clear_all_soft_refs()) {

assert(clear_all_softrefs, "Policy should have been checked earlier");

}

#endif

// hook up weak ref data so it can be used during Mark-Sweep

assert(ref_processor() == NULL, "no stomping");

assert(rp != NULL, "should be non-NULL");

_ref_processor = rp;

rp->setup_policy(clear_all_softrefs);

GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL);

gch->trace_heap_before_gc(_gc_tracer);

// When collecting the permanent generation methodOops may be moving,

// so we either have to flush all bcp data or convert it into bci.

CodeCache::gc_prologue();

Threads::gc_prologue();

// Increment the invocation count for the permanent generation, since it is

// implicitly collected whenever we do a full mark sweep collection.

gch->perm_gen()->stat_record()->invocations++;

// Capture heap size before collection for printing.

size_t gch_prev_used = gch->used();

// Some of the card table updates below assume that the perm gen is

// also being collected.

assert(level == gch->n_gens() - 1,

"All generations are being collected, ergo perm gen too.");

// Capture used regions for each generation that will be

// subject to collection, so that card table adjustments can

// be made intelligently (see clear / invalidate further below).

gch->save_used_regions(level, true /* perm */);

allocate_stacks();

mark_sweep_phase1(level, clear_all_softrefs);

mark_sweep_phase2();

// Don't add any more derived pointers during phase3

COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));

COMPILER2_PRESENT(DerivedPointerTable::set_active(false));

mark_sweep_phase3(level);

VALIDATE_MARK_SWEEP_ONLY(

if (ValidateMarkSweep) {

guarantee(_root_refs_stack->length() == 0, "should be empty by now");

}

)

mark_sweep_phase4();

VALIDATE_MARK_SWEEP_ONLY(

if (ValidateMarkSweep) {

guarantee(_live_oops->length() == _live_oops_moved_to->length(),

"should be the same size");

}

)

restore_marks();

// Set saved marks for allocation profiler (and other things? -- dld)

// (Should this be in general part?)

gch->save_marks();

deallocate_stacks();

// If compaction completely evacuated all generations younger than this

// one, then we can clear the card table. Otherwise, we must invalidate

// it (consider all cards dirty). In the future, we might consider doing

// compaction within generations only, and doing card-table sliding.

bool all_empty = true;

for (int i = 0; all_empty && i < level; i++) {

Generation* g = gch->get_gen(i);

all_empty = all_empty && gch->get_gen(i)->used() == 0;

}

GenRemSet* rs = gch->rem_set();

// Clear/invalidate below make use of the "prev_used_regions" saved earlier.

if (all_empty) {

// We've evacuated all generations below us.

Generation* g = gch->get_gen(level);

rs->clear_into_younger(g, true /* perm */);

} else {

// Invalidate the cards corresponding to the currently used

// region and clear those corresponding to the evacuated region

// of all generations just collected (i.e. level and younger).

rs->invalidate_or_clear(gch->get_gen(level),

true /* younger */,

true /* perm */);

}

Threads::gc_epilogue();

CodeCache::gc_epilogue();

JvmtiExport::gc_epilogue();

if (PrintGC && !PrintGCDetails) {

gch->print_heap_change(gch_prev_used);

}

// refs processing: clean slate

_ref_processor = NULL;

// Update heap occupancy information which is used as

// input to soft ref clearing policy at the next gc.

Universe::update_heap_info_at_gc();

// Update time of last gc for all generations we collected

// (which curently is all the generations in the heap).

// We need to use a monotonically non-deccreasing time in ms

// or we will see time-warp warnings and os::javaTimeMillis()

// does not guarantee monotonicity.

jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;

gch->update_time_of_last_gc(now);

gch->trace_heap_after_gc(_gc_tracer);

}

void GenMarkSweep::allocate_stacks() {

GenCollectedHeap* gch = GenCollectedHeap::heap();

// Scratch request on behalf of oldest generation; will do no

// allocation.

ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0);

// $$$ To cut a corner, we'll only use the first scratch block, and then

// revert to malloc.

if (scratch != NULL) {

_preserved_count_max =

scratch->num_words * HeapWordSize / sizeof(PreservedMark);

} else {

_preserved_count_max = 0;

}

_preserved_marks = (PreservedMark*)scratch;

_preserved_count = 0;

#ifdef VALIDATE_MARK_SWEEP

if (ValidateMarkSweep) {

_root_refs_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<void*>(100, true);

_other_refs_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<void*>(100, true);

_adjusted_pointers = new (ResourceObj::C_HEAP, mtGC) GrowableArray<void*>(100, true);

_live_oops = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(100, true);

_live_oops_moved_to = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(100, true);

_live_oops_size = new (ResourceObj::C_HEAP, mtGC) GrowableArray<size_t>(100, true);

}

if (RecordMarkSweepCompaction) {

if (_cur_gc_live_oops == NULL) {

_cur_gc_live_oops = new(ResourceObj::C_HEAP, mtGC) GrowableArray<HeapWord*>(100, true);

_cur_gc_live_oops_moved_to = new(ResourceObj::C_HEAP, mtGC) GrowableArray<HeapWord*>(100, true);

_cur_gc_live_oops_size = new(ResourceObj::C_HEAP, mtGC) GrowableArray<size_t>(100, true);

_last_gc_live_oops = new(ResourceObj::C_HEAP, mtGC) GrowableArray<HeapWord*>(100, true);

_last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP, mtGC) GrowableArray<HeapWord*>(100, true);

_last_gc_live_oops_size = new(ResourceObj::C_HEAP, mtGC) GrowableArray<size_t>(100, true);

} else {

_cur_gc_live_oops->clear();

_cur_gc_live_oops_moved_to->clear();

_cur_gc_live_oops_size->clear();

}

}

#endif

}

void GenMarkSweep::deallocate_stacks() {

if (!UseG1GC) {

GenCollectedHeap* gch = GenCollectedHeap::heap();

gch->release_scratch();

}

_preserved_mark_stack.clear(true);

_preserved_oop_stack.clear(true);

_marking_stack.clear();

_objarray_stack.clear(true);

_revisit_klass_stack.clear(true);

_revisit_mdo_stack.clear(true);

#ifdef VALIDATE_MARK_SWEEP

if (ValidateMarkSweep) {

delete _root_refs_stack;

delete _other_refs_stack;

delete _adjusted_pointers;

delete _live_oops;

delete _live_oops_size;

delete _live_oops_moved_to;

_live_oops_index = 0;

_live_oops_index_at_perm = 0;

}

#endif

}

void GenMarkSweep::mark_sweep_phase1(int level,

bool clear_all_softrefs) {

// Recursively traverse all live objects and mark them

GCTraceTime tm("phase 1", PrintGC && Verbose, true, _gc_timer);

trace(" 1");

VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));

GenCollectedHeap* gch = GenCollectedHeap::heap();

// Because follow_root_closure is created statically, cannot

// use OopsInGenClosure constructor which takes a generation,

// as the Universe has not been created when the static constructors

// are run.

follow_root_closure.set_orig_generation(gch->get_gen(level));

gch->gen_process_strong_roots(level,

false, // Younger gens are not roots.

true, // activate StrongRootsScope

true, // Collecting permanent generation.

SharedHeap::SO_SystemClasses,

&follow_root_closure,

true, // walk code active on stacks

&follow_root_closure);

// Process reference objects found during marking

{

ref_processor()->setup_policy(clear_all_softrefs);

const ReferenceProcessorStats& stats =

ref_processor()->process_discovered_references(

&is_alive, &keep_alive, &follow_stack_closure, NULL, _gc_timer);

gc_tracer()->report_gc_reference_stats(stats);

}

// Follow system dictionary roots and unload classes

bool purged_class = SystemDictionary::do_unloading(&is_alive);

// Follow code cache roots

CodeCache::do_unloading(&is_alive, &keep_alive, purged_class);

follow_stack(); // Flush marking stack

// Update subklass/sibling/implementor links of live klasses

follow_weak_klass_links();

assert(_marking_stack.is_empty(), "just drained");

// Visit memoized MDO's and clear any unmarked weak refs

follow_mdo_weak_refs();

assert(_marking_stack.is_empty(), "just drained");

// Visit interned string tables and delete unmarked oops

StringTable::unlink(&is_alive);

// Clean up unreferenced symbols in symbol table.

SymbolTable::unlink();

assert(_marking_stack.is_empty(), "stack should be empty by now");

gc_tracer()->report_object_count_after_gc(&is_alive);

}

void GenMarkSweep::mark_sweep_phase2() {

// Now all live objects are marked, compute the new object addresses.

// It is imperative that we traverse perm_gen LAST. If dead space is

// allowed a range of dead object may get overwritten by a dead int

// array. If perm_gen is not traversed last a klassOop may get

// overwritten. This is fine since it is dead, but if the class has dead

// instances we have to skip them, and in order to find their size we

// need the klassOop!

//

// It is not required that we traverse spaces in the same order in

// phase2, phase3 and phase4, but the ValidateMarkSweep live oops

// tracking expects us to do so. See comment under phase4.

GenCollectedHeap* gch = GenCollectedHeap::heap();

Generation* pg = gch->perm_gen();

GCTraceTime tm("phase 2", PrintGC && Verbose, true, _gc_timer);

trace("2");

VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));

gch->prepare_for_compaction();

VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index);

CompactPoint perm_cp(pg, NULL, NULL);

pg->prepare_for_compaction(&perm_cp);

}

class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure {

public:

void do_generation(Generation* gen) {

gen->adjust_pointers();

}

};

void GenMarkSweep::mark_sweep_phase3(int level) {

GenCollectedHeap* gch = GenCollectedHeap::heap();

Generation* pg = gch->perm_gen();

// Adjust the pointers to reflect the new locations

GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer);

trace("3");

VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));

// Needs to be done before the system dictionary is adjusted.

pg->pre_adjust_pointers();

// Because the two closures below are created statically, cannot

// use OopsInGenClosure constructor which takes a generation,

// as the Universe has not been created when the static constructors

// are run.

adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level));

adjust_pointer_closure.set_orig_generation(gch->get_gen(level));

gch->gen_process_strong_roots(level,

false, // Younger gens are not roots.

true, // activate StrongRootsScope

true, // Collecting permanent generation.

SharedHeap::SO_AllClasses,

&adjust_root_pointer_closure,

false, // do not walk code

&adjust_root_pointer_closure);

// Now adjust pointers in remaining weak roots. (All of which should

// have been cleared if they pointed to non-surviving objects.)

CodeBlobToOopClosure adjust_code_pointer_closure(&adjust_pointer_closure,

/*do_marking=*/ false);

gch->gen_process_weak_roots(&adjust_root_pointer_closure,

&adjust_code_pointer_closure,

&adjust_pointer_closure);

adjust_marks();

GenAdjustPointersClosure blk;

gch->generation_iterate(&blk, true);

pg->adjust_pointers();

}

class GenCompactClosure: public GenCollectedHeap::GenClosure {

public:

void do_generation(Generation* gen) {

gen->compact();

}

};

void GenMarkSweep::mark_sweep_phase4() {

// All pointers are now adjusted, move objects accordingly

// It is imperative that we traverse perm_gen first in phase4. All

// classes must be allocated earlier than their instances, and traversing

// perm_gen first makes sure that all klassOops have moved to their new

// location before any instance does a dispatch through it's klass!

// The ValidateMarkSweep live oops tracking expects us to traverse spaces

// in the same order in phase2, phase3 and phase4. We don't quite do that

// here (perm_gen first rather than last), so we tell the validate code

// to use a higher index (saved from phase2) when verifying perm_gen.

GenCollectedHeap* gch = GenCollectedHeap::heap();

Generation* pg = gch->perm_gen();

GCTraceTime tm("phase 4", PrintGC && Verbose, true, _gc_timer);

trace("4");

VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true));

pg->compact();

VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));

GenCompactClosure blk;

gch->generation_iterate(&blk, true);

VALIDATE_MARK_SWEEP_ONLY(compaction_complete());

pg->post_compact(); // Shared spaces verification.

}