#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP

#define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP

#include "gc_implementation/g1/concurrentMark.hpp"

#include "gc_implementation/g1/evacuationInfo.hpp"

#include "gc_implementation/g1/g1AllocRegion.hpp"

#include "gc_implementation/g1/g1HRPrinter.hpp"

#include "gc_implementation/g1/g1MonitoringSupport.hpp"

#include "gc_implementation/g1/g1RemSet.hpp"

#include "gc_implementation/g1/g1YCTypes.hpp"

#include "gc_implementation/g1/heapRegionSeq.hpp"

#include "gc_implementation/g1/heapRegionSets.hpp"

#include "gc_implementation/shared/hSpaceCounters.hpp"

#include "gc_implementation/shared/parGCAllocBuffer.hpp"

#include "memory/barrierSet.hpp"

#include "memory/memRegion.hpp"

#include "memory/sharedHeap.hpp"

#include "utilities/stack.hpp"

class HeapRegion;

class HRRSCleanupTask;

class PermanentGenerationSpec;

class GenerationSpec;

class OopsInHeapRegionClosure;

class G1ScanHeapEvacClosure;

class ObjectClosure;

class SpaceClosure;

class CompactibleSpaceClosure;

class Space;

class G1CollectorPolicy;

class GenRemSet;

class G1RemSet;

class HeapRegionRemSetIterator;

class ConcurrentMark;

class ConcurrentMarkThread;

class ConcurrentG1Refine;

class ConcurrentGCTimer;

class GenerationCounters;

class STWGCTimer;

class G1NewTracer;

class G1OldTracer;

class EvacuationFailedInfo;

typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;

typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;

typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )

typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )

enum GCAllocPurpose {

GCAllocForTenured,

GCAllocForSurvived,

GCAllocPurposeCount

};

class YoungList : public CHeapObj<mtGC> {

private:

G1CollectedHeap* _g1h;

HeapRegion* _head;

HeapRegion* _survivor_head;

HeapRegion* _survivor_tail;

HeapRegion* _curr;

uint _length;

uint _survivor_length;

size_t _last_sampled_rs_lengths;

size_t _sampled_rs_lengths;

void empty_list(HeapRegion* list);

public:

YoungList(G1CollectedHeap* g1h);

void push_region(HeapRegion* hr);

void add_survivor_region(HeapRegion* hr);

void empty_list();

bool is_empty() { return _length == 0; }

uint length() { return _length; }

uint survivor_length() { return _survivor_length; }

// Currently we do not keep track of the used byte sum for the

// young list and the survivors and it'd be quite a lot of work to

// do so. When we'll eventually replace the young list with

// instances of HeapRegionLinkedList we'll get that for free. So,

// we'll report the more accurate information then.

size_t eden_used_bytes() {

assert(length() >= survivor_length(), "invariant");

return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;

}

size_t survivor_used_bytes() {

return (size_t) survivor_length() * HeapRegion::GrainBytes;

}

void rs_length_sampling_init();

bool rs_length_sampling_more();

void rs_length_sampling_next();

void reset_sampled_info() {

_last_sampled_rs_lengths = 0;

}

size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }

// for development purposes

void reset_auxilary_lists();

void clear() { _head = NULL; _length = 0; }

void clear_survivors() {

_survivor_head = NULL;

_survivor_tail = NULL;

_survivor_length = 0;

}

HeapRegion* first_region() { return _head; }

HeapRegion* first_survivor_region() { return _survivor_head; }

HeapRegion* last_survivor_region() { return _survivor_tail; }

// debugging

bool check_list_well_formed();

bool check_list_empty(bool check_sample = true);

void print();

};

class MutatorAllocRegion : public G1AllocRegion {

protected:

virtual HeapRegion* allocate_new_region(size_t word_size, bool force);

virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);

public:

MutatorAllocRegion()

: G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }

};

class G1STWIsAliveClosure: public BoolObjectClosure {

G1CollectedHeap* _g1;

public:

G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}

void do_object(oop p) { assert(false, "Do not call."); }

bool do_object_b(oop p);

};

class SurvivorGCAllocRegion : public G1AllocRegion {

protected:

virtual HeapRegion* allocate_new_region(size_t word_size, bool force);

virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);

public:

SurvivorGCAllocRegion()

: G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }

};

class OldGCAllocRegion : public G1AllocRegion {

protected:

virtual HeapRegion* allocate_new_region(size_t word_size, bool force);

virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);

public:

OldGCAllocRegion()

: G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }

};

class RefineCardTableEntryClosure;

class G1CollectedHeap : public SharedHeap {

friend class VM_G1CollectForAllocation;

friend class VM_GenCollectForPermanentAllocation;

friend class VM_G1CollectFull;

friend class VM_G1IncCollectionPause;

friend class VMStructs;

friend class MutatorAllocRegion;

friend class SurvivorGCAllocRegion;

friend class OldGCAllocRegion;

// Closures used in implementation.

template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>

friend class G1ParCopyClosure;

friend class G1IsAliveClosure;

friend class G1EvacuateFollowersClosure;

friend class G1ParScanThreadState;

friend class G1ParScanClosureSuper;

friend class G1ParEvacuateFollowersClosure;

friend class G1ParTask;

friend class G1FreeGarbageRegionClosure;

friend class RefineCardTableEntryClosure;

friend class G1PrepareCompactClosure;

friend class RegionSorter;

friend class RegionResetter;

friend class CountRCClosure;

friend class EvacPopObjClosure;

friend class G1ParCleanupCTTask;

// Other related classes.

friend class G1MarkSweep;

private:

// The one and only G1CollectedHeap, so static functions can find it.

static G1CollectedHeap* _g1h;

static size_t _humongous_object_threshold_in_words;

// Storage for the G1 heap (excludes the permanent generation).

VirtualSpace _g1_storage;

MemRegion _g1_reserved;

// The part of _g1_storage that is currently committed.

MemRegion _g1_committed;

// The master free list. It will satisfy all new region allocations.

MasterFreeRegionList _free_list;

// The secondary free list which contains regions that have been

// freed up during the cleanup process. This will be appended to the

// master free list when appropriate.

SecondaryFreeRegionList _secondary_free_list;

// It keeps track of the old regions.

MasterOldRegionSet _old_set;

// It keeps track of the humongous regions.

MasterHumongousRegionSet _humongous_set;

// The number of regions we could create by expansion.

uint _expansion_regions;

// The block offset table for the G1 heap.

G1BlockOffsetSharedArray* _bot_shared;

// Tears down the region sets / lists so that they are empty and the

// regions on the heap do not belong to a region set / list. The

// only exception is the humongous set which we leave unaltered. If

// free_list_only is true, it will only tear down the master free

// list. It is called before a Full GC (free_list_only == false) or

// before heap shrinking (free_list_only == true).

void tear_down_region_sets(bool free_list_only);

// Rebuilds the region sets / lists so that they are repopulated to

// reflect the contents of the heap. The only exception is the

// humongous set which was not torn down in the first place. If

// free_list_only is true, it will only rebuild the master free

// list. It is called after a Full GC (free_list_only == false) or

// after heap shrinking (free_list_only == true).

void rebuild_region_sets(bool free_list_only);

// The sequence of all heap regions in the heap.

HeapRegionSeq _hrs;

// Alloc region used to satisfy mutator allocation requests.

MutatorAllocRegion _mutator_alloc_region;

// Alloc region used to satisfy allocation requests by the GC for

// survivor objects.

SurvivorGCAllocRegion _survivor_gc_alloc_region;

// PLAB sizing policy for survivors.

PLABStats _survivor_plab_stats;

// Alloc region used to satisfy allocation requests by the GC for

// old objects.

OldGCAllocRegion _old_gc_alloc_region;

// PLAB sizing policy for tenured objects.

PLABStats _old_plab_stats;

PLABStats* stats_for_purpose(GCAllocPurpose purpose) {

PLABStats* stats = NULL;

switch (purpose) {

case GCAllocForSurvived:

stats = &_survivor_plab_stats;

break;

case GCAllocForTenured:

stats = &_old_plab_stats;

break;

default:

assert(false, "unrecognized GCAllocPurpose");

}

return stats;

}

// The last old region we allocated to during the last GC.

// Typically, it is not full so we should re-use it during the next GC.

HeapRegion* _retained_old_gc_alloc_region;

// It specifies whether we should attempt to expand the heap after a

// region allocation failure. If heap expansion fails we set this to

// false so that we don't re-attempt the heap expansion (it's likely

// that subsequent expansion attempts will also fail if one fails).

// Currently, it is only consulted during GC and it's reset at the

// start of each GC.

bool _expand_heap_after_alloc_failure;

// It resets the mutator alloc region before new allocations can take place.

void init_mutator_alloc_region();

// It releases the mutator alloc region.

void release_mutator_alloc_region();

// It initializes the GC alloc regions at the start of a GC.

void init_gc_alloc_regions(EvacuationInfo& evacuation_info);

// It releases the GC alloc regions at the end of a GC.

void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);

// It does any cleanup that needs to be done on the GC alloc regions

// before a Full GC.

void abandon_gc_alloc_regions();

// Helper for monitoring and management support.

G1MonitoringSupport* _g1mm;

// Determines PLAB size for a particular allocation purpose.

size_t desired_plab_sz(GCAllocPurpose purpose);

// Outside of GC pauses, the number of bytes used in all regions other

// than the current allocation region.

size_t _summary_bytes_used;

// This is used for a quick test on whether a reference points into

// the collection set or not. Basically, we have an array, with one

// byte per region, and that byte denotes whether the corresponding

// region is in the collection set or not. The entry corresponding

// the bottom of the heap, i.e., region 0, is pointed to by

// _in_cset_fast_test_base. The _in_cset_fast_test field has been

// biased so that it actually points to address 0 of the address

// space, to make the test as fast as possible (we can simply shift

// the address to address into it, instead of having to subtract the

// bottom of the heap from the address before shifting it; basically

// it works in the same way the card table works).

bool* _in_cset_fast_test;

// The allocated array used for the fast test on whether a reference

// points into the collection set or not. This field is also used to

// free the array.

bool* _in_cset_fast_test_base;

// The length of the _in_cset_fast_test_base array.

uint _in_cset_fast_test_length;

volatile unsigned _gc_time_stamp;

size_t* _surviving_young_words;

G1HRPrinter _hr_printer;

void setup_surviving_young_words();

void update_surviving_young_words(size_t* surv_young_words);

void cleanup_surviving_young_words();

// It decides whether an explicit GC should start a concurrent cycle

// instead of doing a STW GC. Currently, a concurrent cycle is

// explicitly started if:

// (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or

// (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.

// (c) cause == _g1_humongous_allocation

bool should_do_concurrent_full_gc(GCCause::Cause cause);

// Keeps track of how many "old marking cycles" (i.e., Full GCs or

// concurrent cycles) we have started.

volatile unsigned int _old_marking_cycles_started;

// Keeps track of how many "old marking cycles" (i.e., Full GCs or

// concurrent cycles) we have completed.

volatile unsigned int _old_marking_cycles_completed;

bool _concurrent_cycle_started;

// This is a non-product method that is helpful for testing. It is

// called at the end of a GC and artificially expands the heap by

// allocating a number of dead regions. This way we can induce very

// frequent marking cycles and stress the cleanup / concurrent

// cleanup code more (as all the regions that will be allocated by

// this method will be found dead by the marking cycle).

void allocate_dummy_regions() PRODUCT_RETURN;

// Clear RSets after a compaction. It also resets the GC time stamps.

void clear_rsets_post_compaction();

// If the HR printer is active, dump the state of the regions in the

// heap after a compaction.

void print_hrs_post_compaction();

double verify(bool guard, const char* msg);

void verify_before_gc();

void verify_after_gc();

void log_gc_header();

void log_gc_footer(double pause_time_sec);

// These are macros so that, if the assert fires, we get the correct

// line number, file, etc.

#define heap_locking_asserts_err_msg(_extra_message_) \

err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \

(_extra_message_), \

BOOL_TO_STR(Heap_lock->owned_by_self()), \

BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \

BOOL_TO_STR(Thread::current()->is_VM_thread()))

#define assert_heap_locked() \

do { \

assert(Heap_lock->owned_by_self(), \

heap_locking_asserts_err_msg("should be holding the Heap_lock")); \

} while (0)

#define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \

do { \

assert(Heap_lock->owned_by_self() || \

(SafepointSynchronize::is_at_safepoint() && \

((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \

heap_locking_asserts_err_msg("should be holding the Heap_lock or " \

"should be at a safepoint")); \

} while (0)

#define assert_heap_locked_and_not_at_safepoint() \

do { \

assert(Heap_lock->owned_by_self() && \

!SafepointSynchronize::is_at_safepoint(), \

heap_locking_asserts_err_msg("should be holding the Heap_lock and " \

"should not be at a safepoint")); \

} while (0)

#define assert_heap_not_locked() \

do { \

assert(!Heap_lock->owned_by_self(), \

heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \

} while (0)

#define assert_heap_not_locked_and_not_at_safepoint() \

do { \

assert(!Heap_lock->owned_by_self() && \

!SafepointSynchronize::is_at_safepoint(), \

heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \

"should not be at a safepoint")); \

} while (0)

#define assert_at_safepoint(_should_be_vm_thread_) \

do { \

assert(SafepointSynchronize::is_at_safepoint() && \

((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \

heap_locking_asserts_err_msg("should be at a safepoint")); \

} while (0)

#define assert_not_at_safepoint() \

do { \

assert(!SafepointSynchronize::is_at_safepoint(), \

heap_locking_asserts_err_msg("should not be at a safepoint")); \

} while (0)

protected:

// The young region list.

YoungList* _young_list;

// The current policy object for the collector.

G1CollectorPolicy* _g1_policy;

// This is the second level of trying to allocate a new region. If

// new_region() didn't find a region on the free_list, this call will

// check whether there's anything available on the

// secondary_free_list and/or wait for more regions to appear on

// that list, if _free_regions_coming is set.

HeapRegion* new_region_try_secondary_free_list();

// Try to allocate a single non-humongous HeapRegion sufficient for

// an allocation of the given word_size. If do_expand is true,

// attempt to expand the heap if necessary to satisfy the allocation

// request.

HeapRegion* new_region(size_t word_size, bool do_expand);

// Attempt to satisfy a humongous allocation request of the given

// size by finding a contiguous set of free regions of num_regions

// length and remove them from the master free list. Return the

// index of the first region or G1_NULL_HRS_INDEX if the search

// was unsuccessful.

uint humongous_obj_allocate_find_first(uint num_regions,

size_t word_size);

// Initialize a contiguous set of free regions of length num_regions

// and starting at index first so that they appear as a single

// humongous region.

HeapWord* humongous_obj_allocate_initialize_regions(uint first,

uint num_regions,

size_t word_size);

// Attempt to allocate a humongous object of the given size. Return

// NULL if unsuccessful.

HeapWord* humongous_obj_allocate(size_t word_size);

// The following two methods, allocate_new_tlab() and

// mem_allocate(), are the two main entry points from the runtime

// into the G1's allocation routines. They have the following

// assumptions:

//

// * They should both be called outside safepoints.

//

// * They should both be called without holding the Heap_lock.

//

// * All allocation requests for new TLABs should go to

// allocate_new_tlab().

//

// * All non-TLAB allocation requests should go to mem_allocate().

//

// * If either call cannot satisfy the allocation request using the

// current allocating region, they will try to get a new one. If

// this fails, they will attempt to do an evacuation pause and

// retry the allocation.

//

// * If all allocation attempts fail, even after trying to schedule

// an evacuation pause, allocate_new_tlab() will return NULL,

// whereas mem_allocate() will attempt a heap expansion and/or

// schedule a Full GC.

//

// * We do not allow humongous-sized TLABs. So, allocate_new_tlab

// should never be called with word_size being humongous. All

// humongous allocation requests should go to mem_allocate() which

// will satisfy them with a special path.

virtual HeapWord* allocate_new_tlab(size_t word_size);

virtual HeapWord* mem_allocate(size_t word_size,

bool* gc_overhead_limit_was_exceeded);

// The following three methods take a gc_count_before_ret

// parameter which is used to return the GC count if the method

// returns NULL. Given that we are required to read the GC count

// while holding the Heap_lock, and these paths will take the

// Heap_lock at some point, it's easier to get them to read the GC

// count while holding the Heap_lock before they return NULL instead

// of the caller (namely: mem_allocate()) having to also take the

// Heap_lock just to read the GC count.

// First-level mutator allocation attempt: try to allocate out of

// the mutator alloc region without taking the Heap_lock. This

// should only be used for non-humongous allocations.

inline HeapWord* attempt_allocation(size_t word_size,

unsigned int* gc_count_before_ret);

// Second-level mutator allocation attempt: take the Heap_lock and

// retry the allocation attempt, potentially scheduling a GC

// pause. This should only be used for non-humongous allocations.

HeapWord* attempt_allocation_slow(size_t word_size,

unsigned int* gc_count_before_ret);

// Takes the Heap_lock and attempts a humongous allocation. It can

// potentially schedule a GC pause.

HeapWord* attempt_allocation_humongous(size_t word_size,

unsigned int* gc_count_before_ret);

// Allocation attempt that should be called during safepoints (e.g.,

// at the end of a successful GC). expect_null_mutator_alloc_region

// specifies whether the mutator alloc region is expected to be NULL

// or not.

HeapWord* attempt_allocation_at_safepoint(size_t word_size,

bool expect_null_mutator_alloc_region);

// It dirties the cards that cover the block so that so that the post

// write barrier never queues anything when updating objects on this

// block. It is assumed (and in fact we assert) that the block

// belongs to a young region.

inline void dirty_young_block(HeapWord* start, size_t word_size);

// Allocate blocks during garbage collection. Will ensure an

// allocation region, either by picking one or expanding the

// heap, and then allocate a block of the given size. The block

// may not be a humongous - it must fit into a single heap region.

HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);

HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,

HeapRegion* alloc_region,

bool par,

size_t word_size);

// Ensure that no further allocations can happen in "r", bearing in mind

// that parallel threads might be attempting allocations.

void par_allocate_remaining_space(HeapRegion* r);

// Allocation attempt during GC for a survivor object / PLAB.

inline HeapWord* survivor_attempt_allocation(size_t word_size);

// Allocation attempt during GC for an old object / PLAB.

inline HeapWord* old_attempt_allocation(size_t word_size);

// These methods are the "callbacks" from the G1AllocRegion class.

// For mutator alloc regions.

HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);

void retire_mutator_alloc_region(HeapRegion* alloc_region,

size_t allocated_bytes);

// For GC alloc regions.

HeapRegion* new_gc_alloc_region(size_t word_size, uint count,

GCAllocPurpose ap);

void retire_gc_alloc_region(HeapRegion* alloc_region,

size_t allocated_bytes, GCAllocPurpose ap);

// - if explicit_gc is true, the GC is for a System.gc() or a heap

// inspection request and should collect the entire heap

// - if clear_all_soft_refs is true, all soft references should be

// cleared during the GC

// - if explicit_gc is false, word_size describes the allocation that

// the GC should attempt (at least) to satisfy

// - it returns false if it is unable to do the collection due to the

// GC locker being active, true otherwise

bool do_collection(bool explicit_gc,

bool clear_all_soft_refs,

size_t word_size);

// Callback from VM_G1CollectFull operation.

// Perform a full collection.

void do_full_collection(bool clear_all_soft_refs);

// Resize the heap if necessary after a full collection. If this is

// after a collect-for allocation, "word_size" is the allocation size,

// and will be considered part of the used portion of the heap.

void resize_if_necessary_after_full_collection(size_t word_size);

// Callback from VM_G1CollectForAllocation operation.

// This function does everything necessary/possible to satisfy a

// failed allocation request (including collection, expansion, etc.)

HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);

// Attempting to expand the heap sufficiently

// to support an allocation of the given "word_size". If

// successful, perform the allocation and return the address of the

// allocated block, or else "NULL".

HeapWord* expand_and_allocate(size_t word_size);

// Process any reference objects discovered during

// an incremental evacuation pause.

void process_discovered_references(uint no_of_gc_workers);

// Enqueue any remaining discovered references

// after processing.

void enqueue_discovered_references(uint no_of_gc_workers);

public:

G1MonitoringSupport* g1mm() {

assert(_g1mm != NULL, "should have been initialized");

return _g1mm;

}

// Expand the garbage-first heap by at least the given size (in bytes!).

// Returns true if the heap was expanded by the requested amount;

// false otherwise.

// (Rounds up to a HeapRegion boundary.)

bool expand(size_t expand_bytes);

// Do anything common to GC's.

virtual void gc_prologue(bool full);

virtual void gc_epilogue(bool full);

// We register a region with the fast "in collection set" test. We

// simply set to true the array slot corresponding to this region.

void register_region_with_in_cset_fast_test(HeapRegion* r) {

assert(_in_cset_fast_test_base != NULL, "sanity");

assert(r->in_collection_set(), "invariant");

uint index = r->hrs_index();

assert(index < _in_cset_fast_test_length, "invariant");

assert(!_in_cset_fast_test_base[index], "invariant");

_in_cset_fast_test_base[index] = true;

}

// This is a fast test on whether a reference points into the

// collection set or not. It does not assume that the reference

// points into the heap; if it doesn't, it will return false.

bool in_cset_fast_test(oop obj) {

assert(_in_cset_fast_test != NULL, "sanity");

if (_g1_committed.contains((HeapWord*) obj)) {

// no need to subtract the bottom of the heap from obj,

// _in_cset_fast_test is biased

uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;

bool ret = _in_cset_fast_test[index];

// let's make sure the result is consistent with what the slower

// test returns

assert( ret || !obj_in_cs(obj), "sanity");

assert(!ret || obj_in_cs(obj), "sanity");

return ret;

} else {

return false;

}

}

void clear_cset_fast_test() {

assert(_in_cset_fast_test_base != NULL, "sanity");

memset(_in_cset_fast_test_base, false,

(size_t) _in_cset_fast_test_length * sizeof(bool));

}

// This is called at the start of either a concurrent cycle or a Full

// GC to update the number of old marking cycles started.

void increment_old_marking_cycles_started();

// This is called at the end of either a concurrent cycle or a Full

// GC to update the number of old marking cycles completed. Those two

// can happen in a nested fashion, i.e., we start a concurrent

// cycle, a Full GC happens half-way through it which ends first,

// and then the cycle notices that a Full GC happened and ends

// too. The concurrent parameter is a boolean to help us do a bit

// tighter consistency checking in the method. If concurrent is

// false, the caller is the inner caller in the nesting (i.e., the

// Full GC). If concurrent is true, the caller is the outer caller

// in this nesting (i.e., the concurrent cycle). Further nesting is

// not currently supported. The end of this call also notifies

// the FullGCCount_lock in case a Java thread is waiting for a full

// GC to happen (e.g., it called System.gc() with

// +ExplicitGCInvokesConcurrent).

void increment_old_marking_cycles_completed(bool concurrent);

unsigned int old_marking_cycles_completed() {

return _old_marking_cycles_completed;

}

void register_concurrent_cycle_start(jlong start_time);

void register_concurrent_cycle_end();

void trace_heap_after_concurrent_cycle();

G1YCType yc_type();

G1HRPrinter* hr_printer() { return &_hr_printer; }

protected:

// Shrink the garbage-first heap by at most the given size (in bytes!).

// (Rounds down to a HeapRegion boundary.)

virtual void shrink(size_t expand_bytes);

void shrink_helper(size_t expand_bytes);

#if TASKQUEUE_STATS

static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);

void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;

void reset_taskqueue_stats();

#endif // TASKQUEUE_STATS

// Schedule the VM operation that will do an evacuation pause to

// satisfy an allocation request of word_size. *succeeded will

// return whether the VM operation was successful (it did do an

// evacuation pause) or not (another thread beat us to it or the GC

// locker was active). Given that we should not be holding the

// Heap_lock when we enter this method, we will pass the

// gc_count_before (i.e., total_collections()) as a parameter since

// it has to be read while holding the Heap_lock. Currently, both

// methods that call do_collection_pause() release the Heap_lock

// before the call, so it's easy to read gc_count_before just before.

HeapWord* do_collection_pause(size_t word_size,

unsigned int gc_count_before,

bool* succeeded);

// The guts of the incremental collection pause, executed by the vm

// thread. It returns false if it is unable to do the collection due

// to the GC locker being active, true otherwise

bool do_collection_pause_at_safepoint(double target_pause_time_ms);

// Actually do the work of evacuating the collection set.

void evacuate_collection_set(EvacuationInfo& evacuation_info);

// The g1 remembered set of the heap.

G1RemSet* _g1_rem_set;

// And it's mod ref barrier set, used to track updates for the above.

ModRefBarrierSet* _mr_bs;

// A set of cards that cover the objects for which the Rsets should be updated

// concurrently after the collection.

DirtyCardQueueSet _dirty_card_queue_set;

// The Heap Region Rem Set Iterator.

HeapRegionRemSetIterator** _rem_set_iterator;

// The closure used to refine a single card.

RefineCardTableEntryClosure* _refine_cte_cl;

// A function to check the consistency of dirty card logs.

void check_ct_logs_at_safepoint();

// A DirtyCardQueueSet that is used to hold cards that contain

// references into the current collection set. This is used to

// update the remembered sets of the regions in the collection

// set in the event of an evacuation failure.

DirtyCardQueueSet _into_cset_dirty_card_queue_set;

// After a collection pause, make the regions in the CS into free

// regions.

void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);

// Abandon the current collection set without recording policy

// statistics or updating free lists.

void abandon_collection_set(HeapRegion* cs_head);

// Applies "scan_non_heap_roots" to roots outside the heap,

// "scan_rs" to roots inside the heap (having done "set_region" to

// indicate the region in which the root resides), and does "scan_perm"

// (setting the generation to the perm generation.) If "scan_rs" is

// NULL, then this step is skipped. The "worker_i"

// param is for use with parallel roots processing, and should be

// the "i" of the calling parallel worker thread's work(i) function.

// In the sequential case this param will be ignored.

void g1_process_strong_roots(bool collecting_perm_gen,

ScanningOption so,

OopClosure* scan_non_heap_roots,

OopsInHeapRegionClosure* scan_rs,

OopsInGenClosure* scan_perm,

int worker_i);

// Apply "blk" to all the weak roots of the system. These include

// JNI weak roots, the code cache, system dictionary, symbol table,

// string table, and referents of reachable weak refs.

void g1_process_weak_roots(OopClosure* root_closure,

OopClosure* non_root_closure);

// Frees a non-humongous region by initializing its contents and

// adding it to the free list that's passed as a parameter (this is

// usually a local list which will be appended to the master free

// list later). The used bytes of freed regions are accumulated in

// pre_used. If par is true, the region's RSet will not be freed

// up. The assumption is that this will be done later.

void free_region(HeapRegion* hr,

size_t* pre_used,

FreeRegionList* free_list,

bool par);

// Frees a humongous region by collapsing it into individual regions

// and calling free_region() for each of them. The freed regions

// will be added to the free list that's passed as a parameter (this

// is usually a local list which will be appended to the master free

// list later). The used bytes of freed regions are accumulated in

// pre_used. If par is true, the region's RSet will not be freed

// up. The assumption is that this will be done later.

void free_humongous_region(HeapRegion* hr,

size_t* pre_used,

FreeRegionList* free_list,

HumongousRegionSet* humongous_proxy_set,

bool par);

// Notifies all the necessary spaces that the committed space has

// been updated (either expanded or shrunk). It should be called

// after _g1_storage is updated.

void update_committed_space(HeapWord* old_end, HeapWord* new_end);

// The concurrent marker (and the thread it runs in.)

ConcurrentMark* _cm;

ConcurrentMarkThread* _cmThread;

bool _mark_in_progress;

// The concurrent refiner.

ConcurrentG1Refine* _cg1r;

// The parallel task queues

RefToScanQueueSet *_task_queues;

// True iff a evacuation has failed in the current collection.

bool _evacuation_failed;

EvacuationFailedInfo* _evacuation_failed_info_array;

// Failed evacuations cause some logical from-space objects to have

// forwarding pointers to themselves. Reset them.

void remove_self_forwarding_pointers();

// Together, these store an object with a preserved mark, and its mark value.

Stack<oop, mtGC> _objs_with_preserved_marks;

Stack<markOop, mtGC> _preserved_marks_of_objs;

// Preserve the mark of "obj", if necessary, in preparation for its mark

// word being overwritten with a self-forwarding-pointer.

void preserve_mark_if_necessary(oop obj, markOop m);

// The stack of evac-failure objects left to be scanned.

GrowableArray<oop>* _evac_failure_scan_stack;

// The closure to apply to evac-failure objects.

OopsInHeapRegionClosure* _evac_failure_closure;

// Set the field above.

void

set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {

_evac_failure_closure = evac_failure_closure;

}

// Push "obj" on the scan stack.

void push_on_evac_failure_scan_stack(oop obj);

// Process scan stack entries until the stack is empty.

void drain_evac_failure_scan_stack();

// True iff an invocation of "drain_scan_stack" is in progress; to

// prevent unnecessary recursion.

bool _drain_in_progress;

// Do any necessary initialization for evacuation-failure handling.

// "cl" is the closure that will be used to process evac-failure

// objects.

void init_for_evac_failure(OopsInHeapRegionClosure* cl);

// Do any necessary cleanup for evacuation-failure handling data

// structures.

void finalize_for_evac_failure();

// An attempt to evacuate "obj" has failed; take necessary steps.

oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);

void handle_evacuation_failure_common(oop obj, markOop m);

#ifndef PRODUCT

// Support for forcing evacuation failures. Analogous to

// PromotionFailureALot for the other collectors.

// Records whether G1EvacuationFailureALot should be in effect

// for the current GC

bool _evacuation_failure_alot_for_current_gc;

// Used to record the GC number for interval checking when

// determining whether G1EvaucationFailureALot is in effect

// for the current GC.

size_t _evacuation_failure_alot_gc_number;

// Count of the number of evacuations between failures.

volatile size_t _evacuation_failure_alot_count;

// Set whether G1EvacuationFailureALot should be in effect

// for the current GC (based upon the type of GC and which

// command line flags are set);

inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,

bool during_initial_mark,

bool during_marking);

inline void set_evacuation_failure_alot_for_current_gc();

// Return true if it's time to cause an evacuation failure.

inline bool evacuation_should_fail();

// Reset the G1EvacuationFailureALot counters. Should be called at

// the end of an evacuation pause in which an evacuation failure occurred.

inline void reset_evacuation_should_fail();

#endif // !PRODUCT

// ("Weak") Reference processing support.

//

// G1 has 2 instances of the reference processor class. One

// (_ref_processor_cm) handles reference object discovery

// and subsequent processing during concurrent marking cycles.

//

// The other (_ref_processor_stw) handles reference object

// discovery and processing during full GCs and incremental

// evacuation pauses.

//

// During an incremental pause, reference discovery will be

// temporarily disabled for _ref_processor_cm and will be

// enabled for _ref_processor_stw. At the end of the evacuation

// pause references discovered by _ref_processor_stw will be

// processed and discovery will be disabled. The previous

// setting for reference object discovery for _ref_processor_cm

// will be re-instated.

//

// At the start of marking:

// * Discovery by the CM ref processor is verified to be inactive

// and it's discovered lists are empty.

// * Discovery by the CM ref processor is then enabled.

//

// At the end of marking:

// * Any references on the CM ref processor's discovered

// lists are processed (possibly MT).

//

// At the start of full GC we:

// * Disable discovery by the CM ref processor and

// empty CM ref processor's discovered lists

// (without processing any entries).

// * Verify that the STW ref processor is inactive and it's

// discovered lists are empty.

// * Temporarily set STW ref processor discovery as single threaded.

// * Temporarily clear the STW ref processor's _is_alive_non_header

// field.

// * Finally enable discovery by the STW ref processor.

//

// The STW ref processor is used to record any discovered

// references during the full GC.

//

// At the end of a full GC we:

// * Enqueue any reference objects discovered by the STW ref processor

// that have non-live referents. This has the side-effect of

// making the STW ref processor inactive by disabling discovery.

// * Verify that the CM ref processor is still inactive

// and no references have been placed on it's discovered

// lists (also checked as a precondition during initial marking).

// The (stw) reference processor...

ReferenceProcessor* _ref_processor_stw;

STWGCTimer* _gc_timer_stw;

ConcurrentGCTimer* _gc_timer_cm;

G1OldTracer* _gc_tracer_cm;

G1NewTracer* _gc_tracer_stw;

// During reference object discovery, the _is_alive_non_header

// closure (if non-null) is applied to the referent object to

// determine whether the referent is live. If so then the

// reference object does not need to be 'discovered' and can

// be treated as a regular oop. This has the benefit of reducing

// the number of 'discovered' reference objects that need to

// be processed.

//

// Instance of the is_alive closure for embedding into the

// STW reference processor as the _is_alive_non_header field.

// Supplying a value for the _is_alive_non_header field is

// optional but doing so prevents unnecessary additions to

// the discovered lists during reference discovery.

G1STWIsAliveClosure _is_alive_closure_stw;

// The (concurrent marking) reference processor...

ReferenceProcessor* _ref_processor_cm;

// Instance of the concurrent mark is_alive closure for embedding

// into the Concurrent Marking reference processor as the

// _is_alive_non_header field. Supplying a value for the

// _is_alive_non_header field is optional but doing so prevents

// unnecessary additions to the discovered lists during reference

// discovery.

G1CMIsAliveClosure _is_alive_closure_cm;

// Cache used by G1CollectedHeap::start_cset_region_for_worker().

HeapRegion** _worker_cset_start_region;

// Time stamp to validate the regions recorded in the cache

// used by G1CollectedHeap::start_cset_region_for_worker().

// The heap region entry for a given worker is valid iff

// the associated time stamp value matches the current value

// of G1CollectedHeap::_gc_time_stamp.

unsigned int* _worker_cset_start_region_time_stamp;

enum G1H_process_strong_roots_tasks {

G1H_PS_filter_satb_buffers,

G1H_PS_refProcessor_oops_do,

// Leave this one last.

G1H_PS_NumElements

};

SubTasksDone* _process_strong_tasks;

volatile bool _free_regions_coming;

public:

SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }

void set_refine_cte_cl_concurrency(bool concurrent);

RefToScanQueue *task_queue(int i) const;

// A set of cards where updates happened during the GC

DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }

// A DirtyCardQueueSet that is used to hold cards that contain

// references into the current collection set. This is used to

// update the remembered sets of the regions in the collection

// set in the event of an evacuation failure.

DirtyCardQueueSet& into_cset_dirty_card_queue_set()

{ return _into_cset_dirty_card_queue_set; }

// Create a G1CollectedHeap with the specified policy.

// Must call the initialize method afterwards.

// May not return if something goes wrong.

G1CollectedHeap(G1CollectorPolicy* policy);

// Initialize the G1CollectedHeap to have the initial and

// maximum sizes, permanent generation, and remembered and barrier sets

// specified by the policy object.

jint initialize();

// Initialize weak reference processing.

virtual void ref_processing_init();

void set_par_threads(uint t) {

SharedHeap::set_par_threads(t);

// Done in SharedHeap but oddly there are

// two _process_strong_tasks's in a G1CollectedHeap

// so do it here too.

_process_strong_tasks->set_n_threads(t);

}

// Set _n_par_threads according to a policy TBD.

void set_par_threads();

void set_n_termination(int t) {

_process_strong_tasks->set_n_threads(t);

}

virtual CollectedHeap::Name kind() const {

return CollectedHeap::G1CollectedHeap;

}

// The current policy object for the collector.

G1CollectorPolicy* g1_policy() const { return _g1_policy; }

// Adaptive size policy. No such thing for g1.

virtual AdaptiveSizePolicy* size_policy() { return NULL; }

// The rem set and barrier set.

G1RemSet* g1_rem_set() const { return _g1_rem_set; }

ModRefBarrierSet* mr_bs() const { return _mr_bs; }

// The rem set iterator.

HeapRegionRemSetIterator* rem_set_iterator(int i) {

return _rem_set_iterator[i];

}

HeapRegionRemSetIterator* rem_set_iterator() {

return _rem_set_iterator[0];

}

unsigned get_gc_time_stamp() {

return _gc_time_stamp;

}

void reset_gc_time_stamp() {

_gc_time_stamp = 0;

OrderAccess::fence();

// Clear the cached CSet starting regions and time stamps.

// Their validity is dependent on the GC timestamp.

clear_cset_start_regions();

}

void check_gc_time_stamps() PRODUCT_RETURN;

void increment_gc_time_stamp() {

++_gc_time_stamp;

OrderAccess::fence();

}

// Reset the given region's GC timestamp. If it's starts humongous,

// also reset the GC timestamp of its corresponding

// continues humongous regions too.

void reset_gc_time_stamps(HeapRegion* hr);

void iterate_dirty_card_closure(CardTableEntryClosure* cl,

DirtyCardQueue* into_cset_dcq,

bool concurrent, int worker_i);

// The shared block offset table array.

G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }

// Reference Processing accessors

// The STW reference processor....

ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }

// The Concurrent Marking reference processor...

ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }

ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }

G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }

virtual size_t capacity() const;

virtual size_t used() const;

// This should be called when we're not holding the heap lock. The

// result might be a bit inaccurate.

size_t used_unlocked() const;

size_t recalculate_used() const;

// These virtual functions do the actual allocation.

// Some heaps may offer a contiguous region for shared non-blocking

// allocation, via inlined code (by exporting the address of the top and

// end fields defining the extent of the contiguous allocation region.)

// But G1CollectedHeap doesn't yet support this.

// Return an estimate of the maximum allocation that could be performed

// without triggering any collection or expansion activity. In a

// generational collector, for example, this is probably the largest

// allocation that could be supported (without expansion) in the youngest

// generation. It is "unsafe" because no locks are taken; the result

// should be treated as an approximation, not a guarantee, for use in

// heuristic resizing decisions.

virtual size_t unsafe_max_alloc();

virtual bool is_maximal_no_gc() const {

return _g1_storage.uncommitted_size() == 0;

}

// The total number of regions in the heap.

uint n_regions() { return _hrs.length(); }

// The max number of regions in the heap.

uint max_regions() { return _hrs.max_length(); }

// The number of regions that are completely free.

uint free_regions() { return _free_list.length(); }

// The number of regions that are not completely free.

uint used_regions() { return n_regions() - free_regions(); }

// The number of regions available for "regular" expansion.

uint expansion_regions() { return _expansion_regions; }

// Factory method for HeapRegion instances. It will return NULL if

// the allocation fails.

HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);

void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;

void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;

void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;

void verify_dirty_young_regions() PRODUCT_RETURN;

// verify_region_sets() performs verification over the region

// lists. It will be compiled in the product code to be used when

// necessary (i.e., during heap verification).

void verify_region_sets();

// verify_region_sets_optional() is planted in the code for

// list verification in non-product builds (and it can be enabled in

// product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).

#if HEAP_REGION_SET_FORCE_VERIFY

void verify_region_sets_optional() {

verify_region_sets();

}

#else // HEAP_REGION_SET_FORCE_VERIFY

void verify_region_sets_optional() { }

#endif // HEAP_REGION_SET_FORCE_VERIFY

#ifdef ASSERT

bool is_on_master_free_list(HeapRegion* hr) {

return hr->containing_set() == &_free_list;

}

bool is_in_humongous_set(HeapRegion* hr) {

return hr->containing_set() == &_humongous_set;

}

#endif // ASSERT

// Wrapper for the region list operations that can be called from

// methods outside this class.

void secondary_free_list_add_as_tail(FreeRegionList* list) {

_secondary_free_list.add_as_tail(list);

}

void append_secondary_free_list() {

_free_list.add_as_head(&_secondary_free_list);

}

void append_secondary_free_list_if_not_empty_with_lock() {

// If the secondary free list looks empty there's no reason to

// take the lock and then try to append it.

if (!_secondary_free_list.is_empty()) {

MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);

append_secondary_free_list();

}

}

void old_set_remove(HeapRegion* hr) {

_old_set.remove(hr);

}

size_t non_young_capacity_bytes() {

return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();

}

void set_free_regions_coming();

void reset_free_regions_coming();

bool free_regions_coming() { return _free_regions_coming; }

void wait_while_free_regions_coming();

// Determine whether the given region is one that we are using as an

// old GC alloc region.

bool is_old_gc_alloc_region(HeapRegion* hr) {

return hr == _retained_old_gc_alloc_region;

}

// Perform a collection of the heap; intended for use in implementing

// "System.gc". This probably implies as full a collection as the

// "CollectedHeap" supports.

virtual void collect(GCCause::Cause cause);

// The same as above but assume that the caller holds the Heap_lock.

void collect_locked(GCCause::Cause cause);

// This interface assumes that it's being called by the

// vm thread. It collects the heap assuming that the

// heap lock is already held and that we are executing in

// the context of the vm thread.

virtual void collect_as_vm_thread(GCCause::Cause cause);

// True iff an evacuation has failed in the most-recent collection.

bool evacuation_failed() { return _evacuation_failed; }

// It will free a region if it has allocated objects in it that are

// all dead. It calls either free_region() or

// free_humongous_region() depending on the type of the region that

// is passed to it.

void free_region_if_empty(HeapRegion* hr,

size_t* pre_used,

FreeRegionList* free_list,

OldRegionSet* old_proxy_set,

HumongousRegionSet* humongous_proxy_set,

HRRSCleanupTask* hrrs_cleanup_task,

bool par);

// It appends the free list to the master free list and updates the

// master humongous list according to the contents of the proxy

// list. It also adjusts the total used bytes according to pre_used

// (if par is true, it will do so by taking the ParGCRareEvent_lock).

void update_sets_after_freeing_regions(size_t pre_used,

FreeRegionList* free_list,

OldRegionSet* old_proxy_set,

HumongousRegionSet* humongous_proxy_set,

bool par);

// Returns "TRUE" iff "p" points into the committed areas of the heap.

virtual bool is_in(const void* p) const;

// Return "TRUE" iff the given object address is within the collection

// set.

inline bool obj_in_cs(oop obj);

// Return "TRUE" iff the given object address is in the reserved

// region of g1 (excluding the permanent generation).

bool is_in_g1_reserved(const void* p) const {

return _g1_reserved.contains(p);

}

// Returns a MemRegion that corresponds to the space that has been

// reserved for the heap

MemRegion g1_reserved() {

return _g1_reserved;

}

// Returns a MemRegion that corresponds to the space that has been

// committed in the heap

MemRegion g1_committed() {

return _g1_committed;

}

virtual bool is_in_closed_subset(const void* p) const;

// This resets the card table to all zeros. It is used after

// a collection pause which used the card table to claim cards.

void cleanUpCardTable();

// Iteration functions.

// Iterate over all the ref-containing fields of all objects, calling

// "cl.do_oop" on each.

virtual void oop_iterate(OopClosure* cl) {

oop_iterate(cl, true);

}

void oop_iterate(OopClosure* cl, bool do_perm);

// Same as above, restricted to a memory region.

virtual void oop_iterate(MemRegion mr, OopClosure* cl) {

oop_iterate(mr, cl, true);

}

void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);

// Iterate over all objects, calling "cl.do_object" on each.

virtual void object_iterate(ObjectClosure* cl) {

object_iterate(cl, true);

}

virtual void safe_object_iterate(ObjectClosure* cl) {

object_iterate(cl, true);

}

void object_iterate(ObjectClosure* cl, bool do_perm);

// Iterate over all objects allocated since the last collection, calling

// "cl.do_object" on each. The heap must have been initialized properly

// to support this function, or else this call will fail.

virtual void object_iterate_since_last_GC(ObjectClosure* cl);

// Iterate over all spaces in use in the heap, in ascending address order.

virtual void space_iterate(SpaceClosure* cl);

// Iterate over heap regions, in address order, terminating the

// iteration early if the "doHeapRegion" method returns "true".

void heap_region_iterate(HeapRegionClosure* blk) const;

// Return the region with the given index. It assumes the index is valid.

HeapRegion* region_at(uint index) const { return _hrs.at(index); }

// Divide the heap region sequence into "chunks" of some size (the number

// of regions divided by the number of parallel threads times some

// overpartition factor, currently 4). Assumes that this will be called

// in parallel by ParallelGCThreads worker threads with discinct worker

// ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel

// calls will use the same "claim_value", and that that claim value is

// different from the claim_value of any heap region before the start of

// the iteration. Applies "blk->doHeapRegion" to each of the regions, by

// attempting to claim the first region in each chunk, and, if

// successful, applying the closure to each region in the chunk (and

// setting the claim value of the second and subsequent regions of the

// chunk.) For now requires that "doHeapRegion" always returns "false",

// i.e., that a closure never attempt to abort a traversal.

void heap_region_par_iterate_chunked(HeapRegionClosure* blk,

uint worker,

uint no_of_par_workers,

jint claim_value);

// It resets all the region claim values to the default.

void reset_heap_region_claim_values();

// Resets the claim values of regions in the current

// collection set to the default.

void reset_cset_heap_region_claim_values();

#ifdef ASSERT

bool check_heap_region_claim_values(jint claim_value);

// Same as the routine above but only checks regions in the

// current collection set.

bool check_cset_heap_region_claim_values(jint claim_value);

#endif // ASSERT

// Clear the cached cset start regions and (more importantly)

// the time stamps. Called when we reset the GC time stamp.

void clear_cset_start_regions();

// Given the id of a worker, obtain or calculate a suitable

// starting region for iterating over the current collection set.

HeapRegion* start_cset_region_for_worker(int worker_i);

// This is a convenience method that is used by the

// HeapRegionIterator classes to calculate the starting region for

// each worker so that they do not all start from the same region.

HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);

// Iterate over the regions (if any) in the current collection set.

void collection_set_iterate(HeapRegionClosure* blk);

// As above but starting from region r

void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);

// Returns the first (lowest address) compactible space in the heap.

virtual CompactibleSpace* first_compactible_space();

// A CollectedHeap will contain some number of spaces. This finds the

// space containing a given address, or else returns NULL.

virtual Space* space_containing(const void* addr) const;

// A G1CollectedHeap will contain some number of heap regions. This

// finds the region containing a given address, or else returns NULL.

template <class T>

inline HeapRegion* heap_region_containing(const T addr) const;

// Like the above, but requires "addr" to be in the heap (to avoid a

// null-check), and unlike the above, may return an continuing humongous

// region.

template <class T>

inline HeapRegion* heap_region_containing_raw(const T addr) const;

// A CollectedHeap is divided into a dense sequence of "blocks"; that is,

// each address in the (reserved) heap is a member of exactly

// one block. The defining characteristic of a block is that it is

// possible to find its size, and thus to progress forward to the next

// block. (Blocks may be of different sizes.) Thus, blocks may

// represent Java objects, or they might be free blocks in a

// free-list-based heap (or subheap), as long as the two kinds are

// distinguishable and the size of each is determinable.

// Returns the address of the start of the "block" that contains the

// address "addr". We say "blocks" instead of "object" since some heaps

// may not pack objects densely; a chunk may either be an object or a

// non-object.

virtual HeapWord* block_start(const void* addr) const;

// Requires "addr" to be the start of a chunk, and returns its size.

// "addr + size" is required to be the start of a new chunk, or the end

// of the active area of the heap.

virtual size_t block_size(const HeapWord* addr) const;

// Requires "addr" to be the start of a block, and returns "TRUE" iff

// the block is an object.

virtual bool block_is_obj(const HeapWord* addr) const;

// Does this heap support heap inspection? (+PrintClassHistogram)

virtual bool supports_heap_inspection() const { return true; }

// Section on thread-local allocation buffers (TLABs)

// See CollectedHeap for semantics.

virtual bool supports_tlab_allocation() const;

virtual size_t tlab_capacity(Thread* thr) const;

virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;

// Can a compiler initialize a new object without store barriers?

// This permission only extends from the creation of a new object

// via a TLAB up to the first subsequent safepoint. If such permission

// is granted for this heap type, the compiler promises to call

// defer_store_barrier() below on any slow path allocation of

// a new object for which such initializing store barriers will

// have been elided. G1, like CMS, allows this, but should be

// ready to provide a compensating write barrier as necessary

// if that storage came out of a non-young region. The efficiency

// of this implementation depends crucially on being able to

// answer very efficiently in constant time whether a piece of

// storage in the heap comes from a young region or not.

// See ReduceInitialCardMarks.

virtual bool can_elide_tlab_store_barriers() const {

return true;

}

virtual bool card_mark_must_follow_store() const {

return true;

}

bool is_in_young(const oop obj) {

HeapRegion* hr = heap_region_containing(obj);

return hr != NULL && hr->is_young();

}

#ifdef ASSERT

virtual bool is_in_partial_collection(const void* p);

#endif

virtual bool is_scavengable(const void* addr);

// We don't need barriers for initializing stores to objects

// in the young gen: for the SATB pre-barrier, there is no

// pre-value that needs to be remembered; for the remembered-set

// update logging post-barrier, we don't maintain remembered set

// information for young gen objects.

virtual bool can_elide_initializing_store_barrier(oop new_obj) {

return is_in_young(new_obj);

}

// Can a compiler elide a store barrier when it writes

// a permanent oop into the heap? Applies when the compiler

// is storing x to the heap, where x->is_perm() is true.

virtual bool can_elide_permanent_oop_store_barriers() const {

// At least until perm gen collection is also G1-ified, at

// which point this should return false.

return true;

}

// Returns "true" iff the given word_size is "very large".

static bool isHumongous(size_t word_size) {

// Note this has to be strictly greater-than as the TLABs

// are capped at the humongous thresold and we want to

// ensure that we don't try to allocate a TLAB as

// humongous and that we don't allocate a humongous

// object in a TLAB.

return word_size > _humongous_object_threshold_in_words;

}

// Update mod union table with the set of dirty cards.

void updateModUnion();

// Set the mod union bits corresponding to the given memRegion. Note

// that this is always a safe operation, since it doesn't clear any

// bits.

void markModUnionRange(MemRegion mr);

// Records the fact that a marking phase is no longer in progress.

void set_marking_complete() {

_mark_in_progress = false;

}

void set_marking_started() {

_mark_in_progress = true;

}

bool mark_in_progress() {

return _mark_in_progress;

}

// Print the maximum heap capacity.

virtual size_t max_capacity() const;

virtual jlong millis_since_last_gc();

// Perform any cleanup actions necessary before allowing a verification.

virtual void prepare_for_verify();

// Perform verification.

// vo == UsePrevMarking -> use "prev" marking information,

// vo == UseNextMarking -> use "next" marking information

// vo == UseMarkWord -> use the mark word in the object header

//

// NOTE: Only the "prev" marking information is guaranteed to be

// consistent most of the time, so most calls to this should use

// vo == UsePrevMarking.

// Currently, there is only one case where this is called with

// vo == UseNextMarking, which is to verify the "next" marking

// information at the end of remark.

// Currently there is only one place where this is called with

// vo == UseMarkWord, which is to verify the marking during a

// full GC.

void verify(bool silent, VerifyOption vo);

// Override; it uses the "prev" marking information

virtual void verify(bool silent);

virtual void print_on(outputStream* st) const;

virtual void print_extended_on(outputStream* st) const;

virtual void print_gc_threads_on(outputStream* st) const;

virtual void gc_threads_do(ThreadClosure* tc) const;

// Override

void print_tracing_info() const;

// The following two methods are helpful for debugging RSet issues.

void print_cset_rsets() PRODUCT_RETURN;

void print_all_rsets() PRODUCT_RETURN;

// Convenience function to be used in situations where the heap type can be

// asserted to be this type.

static G1CollectedHeap* heap();

void set_region_short_lived_locked(HeapRegion* hr);

// add appropriate methods for any other surv rate groups

YoungList* young_list() { return _young_list; }

// debugging

bool check_young_list_well_formed() {

return _young_list->check_list_well_formed();

}

bool check_young_list_empty(bool check_heap,

bool check_sample = true);

// *** Stuff related to concurrent marking. It's not clear to me that so

// many of these need to be public.

// The functions below are helper functions that a subclass of

// "CollectedHeap" can use in the implementation of its virtual

// functions.

// This performs a concurrent marking of the live objects in a

// bitmap off to the side.

void doConcurrentMark();

bool isMarkedPrev(oop obj) const;

bool isMarkedNext(oop obj) const;

// Determine if an object is dead, given the object and also

// the region to which the object belongs. An object is dead

// iff a) it was not allocated since the last mark and b) it

// is not marked.

bool is_obj_dead(const oop obj, const HeapRegion* hr) const {

return

!hr->obj_allocated_since_prev_marking(obj) &&

!isMarkedPrev(obj);

}

// This function returns true when an object has been

// around since the previous marking and hasn't yet

// been marked during this marking.

bool is_obj_ill(const oop obj, const HeapRegion* hr) const {

return

!hr->obj_allocated_since_next_marking(obj) &&

!isMarkedNext(obj);

}

// Determine if an object is dead, given only the object itself.

// This will find the region to which the object belongs and

// then call the region version of the same function.

// Added if it is in permanent gen it isn't dead.

// Added if it is NULL it isn't dead.

bool is_obj_dead(const oop obj) const {

const HeapRegion* hr = heap_region_containing(obj);

if (hr == NULL) {

if (Universe::heap()->is_in_permanent(obj))

return false;

else if (obj == NULL) return false;

else return true;

}

else return is_obj_dead(obj, hr);

}

bool is_obj_ill(const oop obj) const {

const HeapRegion* hr = heap_region_containing(obj);

if (hr == NULL) {

if (Universe::heap()->is_in_permanent(obj))

return false;

else if (obj == NULL) return false;

else return true;

}

else return is_obj_ill(obj, hr);

}

// The methods below are here for convenience and dispatch the

// appropriate method depending on value of the given VerifyOption

// parameter. The options for that parameter are:

//

// vo == UsePrevMarking -> use "prev" marking information,

// vo == UseNextMarking -> use "next" marking information,

// vo == UseMarkWord -> use mark word from object header

bool is_obj_dead_cond(const oop obj,

const HeapRegion* hr,

const VerifyOption vo) const {

switch (vo) {

case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);

case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);

case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();

default: ShouldNotReachHere();

}

return false; // keep some compilers happy

}

bool is_obj_dead_cond(const oop obj,

const VerifyOption vo) const {

switch (vo) {

case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);

case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);

case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();

default: ShouldNotReachHere();

}

return false; // keep some compilers happy

}

bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);

HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);

bool is_marked(oop obj, VerifyOption vo);

const char* top_at_mark_start_str(VerifyOption vo);

// The following is just to alert the verification code

// that a full collection has occurred and that the

// remembered sets are no longer up to date.

bool _full_collection;

void set_full_collection() { _full_collection = true;}

void clear_full_collection() {_full_collection = false;}

bool full_collection() {return _full_collection;}

ConcurrentMark* concurrent_mark() const { return _cm; }

ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }

// The dirty cards region list is used to record a subset of regions

// whose cards need clearing. The list if populated during the

// remembered set scanning and drained during the card table

// cleanup. Although the methods are reentrant, population/draining

// phases must not overlap. For synchronization purposes the last

// element on the list points to itself.

HeapRegion* _dirty_cards_region_list;

void push_dirty_cards_region(HeapRegion* hr);

HeapRegion* pop_dirty_cards_region();

public:

void stop_conc_gc_threads();

size_t pending_card_num();

size_t cards_scanned();

protected:

size_t _max_heap_capacity;

};

class G1ParGCAllocBuffer: public ParGCAllocBuffer {

private:

bool _retired;

public:

G1ParGCAllocBuffer(size_t gclab_word_size);

void set_buf(HeapWord* buf) {

ParGCAllocBuffer::set_buf(buf);

_retired = false;

}

void retire(bool end_of_gc, bool retain) {

if (_retired)

return;

ParGCAllocBuffer::retire(end_of_gc, retain);

_retired = true;

}

};

class G1ParScanThreadState : public StackObj {

protected:

G1CollectedHeap* _g1h;

RefToScanQueue* _refs;

DirtyCardQueue _dcq;

CardTableModRefBS* _ct_bs;

G1RemSet* _g1_rem;

G1ParGCAllocBuffer _surviving_alloc_buffer;

G1ParGCAllocBuffer _tenured_alloc_buffer;

G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];

ageTable _age_table;

size_t _alloc_buffer_waste;

size_t _undo_waste;

OopsInHeapRegionClosure* _evac_failure_cl;

G1ParScanHeapEvacClosure* _evac_cl;

G1ParScanPartialArrayClosure* _partial_scan_cl;

int _hash_seed;

uint _queue_num;

size_t _term_attempts;

double _start;

double _start_strong_roots;

double _strong_roots_time;

double _start_term;

double _term_time;

// Map from young-age-index (0 == not young, 1 is youngest) to

// surviving words. base is what we get back from the malloc call

size_t* _surviving_young_words_base;

// this points into the array, as we use the first few entries for padding

size_t* _surviving_young_words;

#define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))

void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }

void add_to_undo_waste(size_t waste) { _undo_waste += waste; }

DirtyCardQueue& dirty_card_queue() { return _dcq; }

CardTableModRefBS* ctbs() { return _ct_bs; }

template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {

if (!from->is_survivor()) {

_g1_rem->par_write_ref(from, p, tid);

}

}

template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {

// If the new value of the field points to the same region or

// is the to-space, we don't need to include it in the Rset updates.

if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {

size_t card_index = ctbs()->index_for(p);

// If the card hasn't been added to the buffer, do it.

if (ctbs()->mark_card_deferred(card_index)) {

dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));

}

}

}

public:

G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);

~G1ParScanThreadState() {

FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);

}

RefToScanQueue* refs() { return _refs; }

ageTable* age_table() { return &_age_table; }

G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {

return _alloc_buffers[purpose];

}

size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }

size_t undo_waste() const { return _undo_waste; }

#ifdef ASSERT

bool verify_ref(narrowOop* ref) const;

bool verify_ref(oop* ref) const;

bool verify_task(StarTask ref) const;

#endif // ASSERT

template <class T> void push_on_queue(T* ref) {

assert(verify_ref(ref), "sanity");

refs()->push(ref);

}

template <class T> void update_rs(HeapRegion* from, T* p, int tid) {

if (G1DeferredRSUpdate) {

deferred_rs_update(from, p, tid);

} else {

immediate_rs_update(from, p, tid);

}

}

HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {

HeapWord* obj = NULL;

size_t gclab_word_size = _g1h->desired_plab_sz(purpose);

if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {

G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);

add_to_alloc_buffer_waste(alloc_buf->words_remaining());

alloc_buf->retire(false /* end_of_gc */, false /* retain */);

HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);

if (buf == NULL) return NULL; // Let caller handle allocation failure.

// Otherwise.

alloc_buf->set_word_size(gclab_word_size);

alloc_buf->set_buf(buf);

obj = alloc_buf->allocate(word_sz);

assert(obj != NULL, "buffer was definitely big enough...");

} else {

obj = _g1h->par_allocate_during_gc(purpose, word_sz);

}

return obj;

}

HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {

HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);

if (obj != NULL) return obj;

return allocate_slow(purpose, word_sz);

}

void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {

if (alloc_buffer(purpose)->contains(obj)) {

assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),

"should contain whole object");

alloc_buffer(purpose)->undo_allocation(obj, word_sz);

} else {

CollectedHeap::fill_with_object(obj, word_sz);

add_to_undo_waste(word_sz);

}

}

void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {

_evac_failure_cl = evac_failure_cl;

}

OopsInHeapRegionClosure* evac_failure_closure() {

return _evac_failure_cl;

}

void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {

_evac_cl = evac_cl;

}

void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {

_partial_scan_cl = partial_scan_cl;

}

int* hash_seed() { return &_hash_seed; }

uint queue_num() { return _queue_num; }

size_t term_attempts() const { return _term_attempts; }

void note_term_attempt() { _term_attempts++; }

void start_strong_roots() {

_start_strong_roots = os::elapsedTime();

}

void end_strong_roots() {

_strong_roots_time += (os::elapsedTime() - _start_strong_roots);

}

double strong_roots_time() const { return _strong_roots_time; }

void start_term_time() {

note_term_attempt();

_start_term = os::elapsedTime();

}

void end_term_time() {

_term_time += (os::elapsedTime() - _start_term);

}

double term_time() const { return _term_time; }

double elapsed_time() const {

return os::elapsedTime() - _start;

}

static void

print_termination_stats_hdr(outputStream* const st = gclog_or_tty);

void

print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;

size_t* surviving_young_words() {

// We add on to hide entry 0 which accumulates surviving words for

// age -1 regions (i.e. non-young ones)

return _surviving_young_words;

}

void retire_alloc_buffers() {

for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {

size_t waste = _alloc_buffers[ap]->words_remaining();

add_to_alloc_buffer_waste(waste);

_alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),

true /* end_of_gc */,

false /* retain */);

}

}

template <class T> void deal_with_reference(T* ref_to_scan) {

if (has_partial_array_mask(ref_to_scan)) {

_partial_scan_cl->do_oop_nv(ref_to_scan);

} else {

// Note: we can use "raw" versions of "region_containing" because

// "obj_to_scan" is definitely in the heap, and is not in a

// humongous region.

HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);

_evac_cl->set_region(r);

_evac_cl->do_oop_nv(ref_to_scan);

}

}

void deal_with_reference(StarTask ref) {

assert(verify_task(ref), "sanity");

if (ref.is_narrow()) {

deal_with_reference((narrowOop*)ref);

} else {

deal_with_reference((oop*)ref);

}

}

void trim_queue();

};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP