1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/evacuationInfo.hpp"
30 #include "gc_implementation/g1/g1AllocRegion.hpp"
31 #include "gc_implementation/g1/g1BiasedArray.hpp"
32 #include "gc_implementation/g1/g1HRPrinter.hpp"
33 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
34 #include "gc_implementation/g1/g1RemSet.hpp"
35 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
36 #include "gc_implementation/g1/g1YCTypes.hpp"
37 #include "gc_implementation/g1/heapRegionSeq.hpp"
38 #include "gc_implementation/g1/heapRegionSet.hpp"
39 #include "gc_implementation/shared/hSpaceCounters.hpp"
40 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
41 #include "memory/barrierSet.hpp"
42 #include "memory/memRegion.hpp"
43 #include "memory/sharedHeap.hpp"
44 #include "utilities/stack.hpp"
45
46 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
47 // It uses the "Garbage First" heap organization and algorithm, which
48 // may combine concurrent marking with parallel, incremental compaction of
49 // heap subsets that will yield large amounts of garbage.
50
51 // Forward declarations
52 class HeapRegion;
53 class HRRSCleanupTask;
54 class GenerationSpec;
55 class OopsInHeapRegionClosure;
56 class G1KlassScanClosure;
57 class G1ScanHeapEvacClosure;
58 class ObjectClosure;
59 class SpaceClosure;
60 class CompactibleSpaceClosure;
61 class Space;
62 class G1CollectorPolicy;
63 class GenRemSet;
64 class G1RemSet;
65 class HeapRegionRemSetIterator;
66 class ConcurrentMark;
67 class ConcurrentMarkThread;
68 class ConcurrentG1Refine;
69 class ConcurrentGCTimer;
70 class GenerationCounters;
71 class STWGCTimer;
72 class G1NewTracer;
73 class G1OldTracer;
74 class EvacuationFailedInfo;
75 class nmethod;
76 class Ticks;
77
78 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
79 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
80
81 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
82 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
83
84 enum GCAllocPurpose {
85 GCAllocForTenured,
86 GCAllocForSurvived,
87 GCAllocPurposeCount
88 };
89
90 class YoungList : public CHeapObj<mtGC> {
91 private:
92 G1CollectedHeap* _g1h;
93
94 HeapRegion* _head;
95
96 HeapRegion* _survivor_head;
97 HeapRegion* _survivor_tail;
98
99 HeapRegion* _curr;
100
101 uint _length;
102 uint _survivor_length;
103
104 size_t _last_sampled_rs_lengths;
105 size_t _sampled_rs_lengths;
106
107 void empty_list(HeapRegion* list);
108
109 public:
110 YoungList(G1CollectedHeap* g1h);
111
112 void push_region(HeapRegion* hr);
113 void add_survivor_region(HeapRegion* hr);
114
115 void empty_list();
116 bool is_empty() { return _length == 0; }
117 uint length() { return _length; }
118 uint survivor_length() { return _survivor_length; }
119
120 // Currently we do not keep track of the used byte sum for the
121 // young list and the survivors and it'd be quite a lot of work to
122 // do so. When we'll eventually replace the young list with
123 // instances of HeapRegionLinkedList we'll get that for free. So,
124 // we'll report the more accurate information then.
125 size_t eden_used_bytes() {
126 assert(length() >= survivor_length(), "invariant");
127 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
128 }
129 size_t survivor_used_bytes() {
130 return (size_t) survivor_length() * HeapRegion::GrainBytes;
131 }
132
133 void rs_length_sampling_init();
134 bool rs_length_sampling_more();
135 void rs_length_sampling_next();
136
137 void reset_sampled_info() {
138 _last_sampled_rs_lengths = 0;
139 }
140 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
141
142 // for development purposes
143 void reset_auxilary_lists();
144 void clear() { _head = NULL; _length = 0; }
145
146 void clear_survivors() {
147 _survivor_head = NULL;
148 _survivor_tail = NULL;
149 _survivor_length = 0;
150 }
151
152 HeapRegion* first_region() { return _head; }
153 HeapRegion* first_survivor_region() { return _survivor_head; }
154 HeapRegion* last_survivor_region() { return _survivor_tail; }
155
156 // debugging
157 bool check_list_well_formed();
158 bool check_list_empty(bool check_sample = true);
159 void print();
160 };
161
162 class MutatorAllocRegion : public G1AllocRegion {
163 protected:
164 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
165 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
166 public:
167 MutatorAllocRegion()
168 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
169 };
170
171 class SurvivorGCAllocRegion : public G1AllocRegion {
172 protected:
173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
175 public:
176 SurvivorGCAllocRegion()
177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
178 };
179
180 class OldGCAllocRegion : public G1AllocRegion {
181 protected:
182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
184 public:
185 OldGCAllocRegion()
186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
187 };
188
189 // The G1 STW is alive closure.
190 // An instance is embedded into the G1CH and used as the
191 // (optional) _is_alive_non_header closure in the STW
192 // reference processor. It is also extensively used during
193 // reference processing during STW evacuation pauses.
194 class G1STWIsAliveClosure: public BoolObjectClosure {
195 G1CollectedHeap* _g1;
196 public:
197 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
198 bool do_object_b(oop p);
199 };
200
201 // Instances of this class are used for quick tests on whether a reference points
202 // into the collection set. Each of the array's elements denotes whether the
203 // corresponding region is in the collection set.
204 class G1FastCSetBiasedMappedArray : public G1BiasedMappedArray<bool> {
205 protected:
206 bool default_value() const { return false; }
207 public:
208 void clear() { G1BiasedMappedArray<bool>::clear(); }
209 };
210
211 class RefineCardTableEntryClosure;
212
213 class G1CollectedHeap : public SharedHeap {
214 friend class VM_G1CollectForAllocation;
215 friend class VM_G1CollectFull;
216 friend class VM_G1IncCollectionPause;
217 friend class VMStructs;
218 friend class MutatorAllocRegion;
219 friend class SurvivorGCAllocRegion;
220 friend class OldGCAllocRegion;
221
222 // Closures used in implementation.
223 template <G1Barrier barrier, bool do_mark_object>
224 friend class G1ParCopyClosure;
225 friend class G1IsAliveClosure;
226 friend class G1EvacuateFollowersClosure;
227 friend class G1ParScanThreadState;
228 friend class G1ParScanClosureSuper;
229 friend class G1ParEvacuateFollowersClosure;
230 friend class G1ParTask;
231 friend class G1FreeGarbageRegionClosure;
232 friend class RefineCardTableEntryClosure;
233 friend class G1PrepareCompactClosure;
234 friend class RegionSorter;
235 friend class RegionResetter;
236 friend class CountRCClosure;
237 friend class EvacPopObjClosure;
238 friend class G1ParCleanupCTTask;
239
240 // Other related classes.
241 friend class G1MarkSweep;
242
243 private:
244 // The one and only G1CollectedHeap, so static functions can find it.
245 static G1CollectedHeap* _g1h;
246
247 static size_t _humongous_object_threshold_in_words;
248
249 // Storage for the G1 heap.
250 VirtualSpace _g1_storage;
251 MemRegion _g1_reserved;
252
253 // The part of _g1_storage that is currently committed.
254 MemRegion _g1_committed;
255
256 // The master free list. It will satisfy all new region allocations.
257 FreeRegionList _free_list;
258
259 // The secondary free list which contains regions that have been
260 // freed up during the cleanup process. This will be appended to the
261 // master free list when appropriate.
262 FreeRegionList _secondary_free_list;
263
264 // It keeps track of the old regions.
265 HeapRegionSet _old_set;
266
267 // It keeps track of the humongous regions.
268 HeapRegionSet _humongous_set;
269
270 // The number of regions we could create by expansion.
271 uint _expansion_regions;
272
273 // The block offset table for the G1 heap.
274 G1BlockOffsetSharedArray* _bot_shared;
275
276 // Tears down the region sets / lists so that they are empty and the
277 // regions on the heap do not belong to a region set / list. The
278 // only exception is the humongous set which we leave unaltered. If
279 // free_list_only is true, it will only tear down the master free
280 // list. It is called before a Full GC (free_list_only == false) or
281 // before heap shrinking (free_list_only == true).
282 void tear_down_region_sets(bool free_list_only);
283
284 // Rebuilds the region sets / lists so that they are repopulated to
285 // reflect the contents of the heap. The only exception is the
286 // humongous set which was not torn down in the first place. If
287 // free_list_only is true, it will only rebuild the master free
288 // list. It is called after a Full GC (free_list_only == false) or
289 // after heap shrinking (free_list_only == true).
290 void rebuild_region_sets(bool free_list_only);
291
292 // The sequence of all heap regions in the heap.
293 HeapRegionSeq _hrs;
294
295 // Alloc region used to satisfy mutator allocation requests.
296 MutatorAllocRegion _mutator_alloc_region;
297
298 // Alloc region used to satisfy allocation requests by the GC for
299 // survivor objects.
300 SurvivorGCAllocRegion _survivor_gc_alloc_region;
301
302 // PLAB sizing policy for survivors.
303 PLABStats _survivor_plab_stats;
304
305 // Alloc region used to satisfy allocation requests by the GC for
306 // old objects.
307 OldGCAllocRegion _old_gc_alloc_region;
308
309 // PLAB sizing policy for tenured objects.
310 PLABStats _old_plab_stats;
311
312 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
313 PLABStats* stats = NULL;
314
315 switch (purpose) {
316 case GCAllocForSurvived:
317 stats = &_survivor_plab_stats;
318 break;
319 case GCAllocForTenured:
320 stats = &_old_plab_stats;
321 break;
322 default:
323 assert(false, "unrecognized GCAllocPurpose");
324 }
325
326 return stats;
327 }
328
329 // The last old region we allocated to during the last GC.
330 // Typically, it is not full so we should re-use it during the next GC.
331 HeapRegion* _retained_old_gc_alloc_region;
332
333 // It specifies whether we should attempt to expand the heap after a
334 // region allocation failure. If heap expansion fails we set this to
335 // false so that we don't re-attempt the heap expansion (it's likely
336 // that subsequent expansion attempts will also fail if one fails).
337 // Currently, it is only consulted during GC and it's reset at the
338 // start of each GC.
339 bool _expand_heap_after_alloc_failure;
340
341 // It resets the mutator alloc region before new allocations can take place.
342 void init_mutator_alloc_region();
343
344 // It releases the mutator alloc region.
345 void release_mutator_alloc_region();
346
347 // It initializes the GC alloc regions at the start of a GC.
348 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
349
350 // It releases the GC alloc regions at the end of a GC.
351 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
352
353 // It does any cleanup that needs to be done on the GC alloc regions
354 // before a Full GC.
355 void abandon_gc_alloc_regions();
356
357 // Helper for monitoring and management support.
358 G1MonitoringSupport* _g1mm;
359
360 // Determines PLAB size for a particular allocation purpose.
361 size_t desired_plab_sz(GCAllocPurpose purpose);
362
363 // Outside of GC pauses, the number of bytes used in all regions other
364 // than the current allocation region.
365 size_t _summary_bytes_used;
366
367 // This array is used for a quick test on whether a reference points into
368 // the collection set or not. Each of the array's elements denotes whether the
369 // corresponding region is in the collection set or not.
370 G1FastCSetBiasedMappedArray _in_cset_fast_test;
371
372 volatile unsigned _gc_time_stamp;
373
374 size_t* _surviving_young_words;
375
376 G1HRPrinter _hr_printer;
377
378 void setup_surviving_young_words();
379 void update_surviving_young_words(size_t* surv_young_words);
380 void cleanup_surviving_young_words();
381
382 // It decides whether an explicit GC should start a concurrent cycle
383 // instead of doing a STW GC. Currently, a concurrent cycle is
384 // explicitly started if:
385 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
386 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
387 // (c) cause == _g1_humongous_allocation
388 bool should_do_concurrent_full_gc(GCCause::Cause cause);
389
390 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
391 // concurrent cycles) we have started.
392 volatile unsigned int _old_marking_cycles_started;
393
394 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
395 // concurrent cycles) we have completed.
396 volatile unsigned int _old_marking_cycles_completed;
397
398 bool _concurrent_cycle_started;
399
400 // This is a non-product method that is helpful for testing. It is
401 // called at the end of a GC and artificially expands the heap by
402 // allocating a number of dead regions. This way we can induce very
403 // frequent marking cycles and stress the cleanup / concurrent
404 // cleanup code more (as all the regions that will be allocated by
405 // this method will be found dead by the marking cycle).
406 void allocate_dummy_regions() PRODUCT_RETURN;
407
408 // Clear RSets after a compaction. It also resets the GC time stamps.
409 void clear_rsets_post_compaction();
410
411 // If the HR printer is active, dump the state of the regions in the
412 // heap after a compaction.
413 void print_hrs_post_compaction();
414
415 double verify(bool guard, const char* msg);
416 void verify_before_gc();
417 void verify_after_gc();
418
419 void log_gc_header();
420 void log_gc_footer(double pause_time_sec);
421
422 // These are macros so that, if the assert fires, we get the correct
423 // line number, file, etc.
424
425 #define heap_locking_asserts_err_msg(_extra_message_) \
426 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
427 (_extra_message_), \
428 BOOL_TO_STR(Heap_lock->owned_by_self()), \
429 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
430 BOOL_TO_STR(Thread::current()->is_VM_thread()))
431
432 #define assert_heap_locked() \
433 do { \
434 assert(Heap_lock->owned_by_self(), \
435 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
436 } while (0)
437
438 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
439 do { \
440 assert(Heap_lock->owned_by_self() || \
441 (SafepointSynchronize::is_at_safepoint() && \
442 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
443 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
444 "should be at a safepoint")); \
445 } while (0)
446
447 #define assert_heap_locked_and_not_at_safepoint() \
448 do { \
449 assert(Heap_lock->owned_by_self() && \
450 !SafepointSynchronize::is_at_safepoint(), \
451 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
452 "should not be at a safepoint")); \
453 } while (0)
454
455 #define assert_heap_not_locked() \
456 do { \
457 assert(!Heap_lock->owned_by_self(), \
458 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
459 } while (0)
460
461 #define assert_heap_not_locked_and_not_at_safepoint() \
462 do { \
463 assert(!Heap_lock->owned_by_self() && \
464 !SafepointSynchronize::is_at_safepoint(), \
465 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
466 "should not be at a safepoint")); \
467 } while (0)
468
469 #define assert_at_safepoint(_should_be_vm_thread_) \
470 do { \
471 assert(SafepointSynchronize::is_at_safepoint() && \
472 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
473 heap_locking_asserts_err_msg("should be at a safepoint")); \
474 } while (0)
475
476 #define assert_not_at_safepoint() \
477 do { \
478 assert(!SafepointSynchronize::is_at_safepoint(), \
479 heap_locking_asserts_err_msg("should not be at a safepoint")); \
480 } while (0)
481
482 protected:
483
484 // The young region list.
485 YoungList* _young_list;
486
487 // The current policy object for the collector.
488 G1CollectorPolicy* _g1_policy;
489
490 // This is the second level of trying to allocate a new region. If
491 // new_region() didn't find a region on the free_list, this call will
492 // check whether there's anything available on the
493 // secondary_free_list and/or wait for more regions to appear on
494 // that list, if _free_regions_coming is set.
495 HeapRegion* new_region_try_secondary_free_list(bool is_old);
496
497 // Try to allocate a single non-humongous HeapRegion sufficient for
498 // an allocation of the given word_size. If do_expand is true,
499 // attempt to expand the heap if necessary to satisfy the allocation
500 // request. If the region is to be used as an old region or for a
501 // humongous object, set is_old to true. If not, to false.
502 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
503
504 // Attempt to satisfy a humongous allocation request of the given
505 // size by finding a contiguous set of free regions of num_regions
506 // length and remove them from the master free list. Return the
507 // index of the first region or G1_NULL_HRS_INDEX if the search
508 // was unsuccessful.
509 uint humongous_obj_allocate_find_first(uint num_regions,
510 size_t word_size);
511
512 // Initialize a contiguous set of free regions of length num_regions
513 // and starting at index first so that they appear as a single
514 // humongous region.
515 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
516 uint num_regions,
517 size_t word_size);
518
519 // Attempt to allocate a humongous object of the given size. Return
520 // NULL if unsuccessful.
521 HeapWord* humongous_obj_allocate(size_t word_size);
522
523 // The following two methods, allocate_new_tlab() and
524 // mem_allocate(), are the two main entry points from the runtime
525 // into the G1's allocation routines. They have the following
526 // assumptions:
527 //
528 // * They should both be called outside safepoints.
529 //
530 // * They should both be called without holding the Heap_lock.
531 //
532 // * All allocation requests for new TLABs should go to
533 // allocate_new_tlab().
534 //
535 // * All non-TLAB allocation requests should go to mem_allocate().
536 //
537 // * If either call cannot satisfy the allocation request using the
538 // current allocating region, they will try to get a new one. If
539 // this fails, they will attempt to do an evacuation pause and
540 // retry the allocation.
541 //
542 // * If all allocation attempts fail, even after trying to schedule
543 // an evacuation pause, allocate_new_tlab() will return NULL,
544 // whereas mem_allocate() will attempt a heap expansion and/or
545 // schedule a Full GC.
546 //
547 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
548 // should never be called with word_size being humongous. All
549 // humongous allocation requests should go to mem_allocate() which
550 // will satisfy them with a special path.
551
552 virtual HeapWord* allocate_new_tlab(size_t word_size);
553
554 virtual HeapWord* mem_allocate(size_t word_size,
555 bool* gc_overhead_limit_was_exceeded);
556
557 // The following three methods take a gc_count_before_ret
558 // parameter which is used to return the GC count if the method
559 // returns NULL. Given that we are required to read the GC count
560 // while holding the Heap_lock, and these paths will take the
561 // Heap_lock at some point, it's easier to get them to read the GC
562 // count while holding the Heap_lock before they return NULL instead
563 // of the caller (namely: mem_allocate()) having to also take the
564 // Heap_lock just to read the GC count.
565
566 // First-level mutator allocation attempt: try to allocate out of
567 // the mutator alloc region without taking the Heap_lock. This
568 // should only be used for non-humongous allocations.
569 inline HeapWord* attempt_allocation(size_t word_size,
570 unsigned int* gc_count_before_ret,
571 int* gclocker_retry_count_ret);
572
573 // Second-level mutator allocation attempt: take the Heap_lock and
574 // retry the allocation attempt, potentially scheduling a GC
575 // pause. This should only be used for non-humongous allocations.
576 HeapWord* attempt_allocation_slow(size_t word_size,
577 unsigned int* gc_count_before_ret,
578 int* gclocker_retry_count_ret);
579
580 // Takes the Heap_lock and attempts a humongous allocation. It can
581 // potentially schedule a GC pause.
582 HeapWord* attempt_allocation_humongous(size_t word_size,
583 unsigned int* gc_count_before_ret,
584 int* gclocker_retry_count_ret);
585
586 // Allocation attempt that should be called during safepoints (e.g.,
587 // at the end of a successful GC). expect_null_mutator_alloc_region
588 // specifies whether the mutator alloc region is expected to be NULL
589 // or not.
590 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
591 bool expect_null_mutator_alloc_region);
592
593 // It dirties the cards that cover the block so that so that the post
594 // write barrier never queues anything when updating objects on this
595 // block. It is assumed (and in fact we assert) that the block
596 // belongs to a young region.
597 inline void dirty_young_block(HeapWord* start, size_t word_size);
598
599 // Allocate blocks during garbage collection. Will ensure an
600 // allocation region, either by picking one or expanding the
601 // heap, and then allocate a block of the given size. The block
602 // may not be a humongous - it must fit into a single heap region.
603 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
604
605 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
606 HeapRegion* alloc_region,
607 bool par,
608 size_t word_size);
609
610 // Ensure that no further allocations can happen in "r", bearing in mind
611 // that parallel threads might be attempting allocations.
612 void par_allocate_remaining_space(HeapRegion* r);
613
614 // Allocation attempt during GC for a survivor object / PLAB.
615 inline HeapWord* survivor_attempt_allocation(size_t word_size);
616
617 // Allocation attempt during GC for an old object / PLAB.
618 inline HeapWord* old_attempt_allocation(size_t word_size);
619
620 // These methods are the "callbacks" from the G1AllocRegion class.
621
622 // For mutator alloc regions.
623 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
624 void retire_mutator_alloc_region(HeapRegion* alloc_region,
625 size_t allocated_bytes);
626
627 // For GC alloc regions.
628 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
629 GCAllocPurpose ap);
630 void retire_gc_alloc_region(HeapRegion* alloc_region,
631 size_t allocated_bytes, GCAllocPurpose ap);
632
633 // - if explicit_gc is true, the GC is for a System.gc() or a heap
634 // inspection request and should collect the entire heap
635 // - if clear_all_soft_refs is true, all soft references should be
636 // cleared during the GC
637 // - if explicit_gc is false, word_size describes the allocation that
638 // the GC should attempt (at least) to satisfy
639 // - it returns false if it is unable to do the collection due to the
640 // GC locker being active, true otherwise
641 bool do_collection(bool explicit_gc,
642 bool clear_all_soft_refs,
643 size_t word_size);
644
645 // Callback from VM_G1CollectFull operation.
646 // Perform a full collection.
647 virtual void do_full_collection(bool clear_all_soft_refs);
648
649 // Resize the heap if necessary after a full collection. If this is
650 // after a collect-for allocation, "word_size" is the allocation size,
651 // and will be considered part of the used portion of the heap.
652 void resize_if_necessary_after_full_collection(size_t word_size);
653
654 // Callback from VM_G1CollectForAllocation operation.
655 // This function does everything necessary/possible to satisfy a
656 // failed allocation request (including collection, expansion, etc.)
657 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
658
659 // Attempting to expand the heap sufficiently
660 // to support an allocation of the given "word_size". If
661 // successful, perform the allocation and return the address of the
662 // allocated block, or else "NULL".
663 HeapWord* expand_and_allocate(size_t word_size);
664
665 // Process any reference objects discovered during
666 // an incremental evacuation pause.
667 void process_discovered_references(uint no_of_gc_workers);
668
669 // Enqueue any remaining discovered references
670 // after processing.
671 void enqueue_discovered_references(uint no_of_gc_workers);
672
673 public:
674
675 G1MonitoringSupport* g1mm() {
676 assert(_g1mm != NULL, "should have been initialized");
677 return _g1mm;
678 }
679
680 // Expand the garbage-first heap by at least the given size (in bytes!).
681 // Returns true if the heap was expanded by the requested amount;
682 // false otherwise.
683 // (Rounds up to a HeapRegion boundary.)
684 bool expand(size_t expand_bytes);
685
686 // Do anything common to GC's.
687 virtual void gc_prologue(bool full);
688 virtual void gc_epilogue(bool full);
689
690 // We register a region with the fast "in collection set" test. We
691 // simply set to true the array slot corresponding to this region.
692 void register_region_with_in_cset_fast_test(HeapRegion* r) {
693 _in_cset_fast_test.set_by_index(r->hrs_index(), true);
694 }
695
696 // This is a fast test on whether a reference points into the
697 // collection set or not. Assume that the reference
698 // points into the heap.
699 inline bool in_cset_fast_test(oop obj);
700
701 void clear_cset_fast_test() {
702 _in_cset_fast_test.clear();
703 }
704
705 // This is called at the start of either a concurrent cycle or a Full
706 // GC to update the number of old marking cycles started.
707 void increment_old_marking_cycles_started();
708
709 // This is called at the end of either a concurrent cycle or a Full
710 // GC to update the number of old marking cycles completed. Those two
711 // can happen in a nested fashion, i.e., we start a concurrent
712 // cycle, a Full GC happens half-way through it which ends first,
713 // and then the cycle notices that a Full GC happened and ends
714 // too. The concurrent parameter is a boolean to help us do a bit
715 // tighter consistency checking in the method. If concurrent is
716 // false, the caller is the inner caller in the nesting (i.e., the
717 // Full GC). If concurrent is true, the caller is the outer caller
718 // in this nesting (i.e., the concurrent cycle). Further nesting is
719 // not currently supported. The end of this call also notifies
720 // the FullGCCount_lock in case a Java thread is waiting for a full
721 // GC to happen (e.g., it called System.gc() with
722 // +ExplicitGCInvokesConcurrent).
723 void increment_old_marking_cycles_completed(bool concurrent);
724
725 unsigned int old_marking_cycles_completed() {
726 return _old_marking_cycles_completed;
727 }
728
729 void register_concurrent_cycle_start(const Ticks& start_time);
730 void register_concurrent_cycle_end();
731 void trace_heap_after_concurrent_cycle();
732
733 G1YCType yc_type();
734
735 G1HRPrinter* hr_printer() { return &_hr_printer; }
736
737 // Frees a non-humongous region by initializing its contents and
738 // adding it to the free list that's passed as a parameter (this is
739 // usually a local list which will be appended to the master free
740 // list later). The used bytes of freed regions are accumulated in
741 // pre_used. If par is true, the region's RSet will not be freed
742 // up. The assumption is that this will be done later.
743 // The locked parameter indicates if the caller has already taken
744 // care of proper synchronization. This may allow some optimizations.
745 void free_region(HeapRegion* hr,
746 FreeRegionList* free_list,
747 bool par,
748 bool locked = false);
749
750 // Frees a humongous region by collapsing it into individual regions
751 // and calling free_region() for each of them. The freed regions
752 // will be added to the free list that's passed as a parameter (this
753 // is usually a local list which will be appended to the master free
754 // list later). The used bytes of freed regions are accumulated in
755 // pre_used. If par is true, the region's RSet will not be freed
756 // up. The assumption is that this will be done later.
757 void free_humongous_region(HeapRegion* hr,
758 FreeRegionList* free_list,
759 bool par);
760 protected:
761
762 // Shrink the garbage-first heap by at most the given size (in bytes!).
763 // (Rounds down to a HeapRegion boundary.)
764 virtual void shrink(size_t expand_bytes);
765 void shrink_helper(size_t expand_bytes);
766
767 #if TASKQUEUE_STATS
768 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
769 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
770 void reset_taskqueue_stats();
771 #endif // TASKQUEUE_STATS
772
773 // Schedule the VM operation that will do an evacuation pause to
774 // satisfy an allocation request of word_size. *succeeded will
775 // return whether the VM operation was successful (it did do an
776 // evacuation pause) or not (another thread beat us to it or the GC
777 // locker was active). Given that we should not be holding the
778 // Heap_lock when we enter this method, we will pass the
779 // gc_count_before (i.e., total_collections()) as a parameter since
780 // it has to be read while holding the Heap_lock. Currently, both
781 // methods that call do_collection_pause() release the Heap_lock
782 // before the call, so it's easy to read gc_count_before just before.
783 HeapWord* do_collection_pause(size_t word_size,
784 unsigned int gc_count_before,
785 bool* succeeded,
786 GCCause::Cause gc_cause);
787
788 // The guts of the incremental collection pause, executed by the vm
789 // thread. It returns false if it is unable to do the collection due
790 // to the GC locker being active, true otherwise
791 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
792
793 // Actually do the work of evacuating the collection set.
794 void evacuate_collection_set(EvacuationInfo& evacuation_info);
795
796 // The g1 remembered set of the heap.
797 G1RemSet* _g1_rem_set;
798
799 // A set of cards that cover the objects for which the Rsets should be updated
800 // concurrently after the collection.
801 DirtyCardQueueSet _dirty_card_queue_set;
802
803 // The closure used to refine a single card.
804 RefineCardTableEntryClosure* _refine_cte_cl;
805
806 // A function to check the consistency of dirty card logs.
807 void check_ct_logs_at_safepoint();
808
809 // A DirtyCardQueueSet that is used to hold cards that contain
810 // references into the current collection set. This is used to
811 // update the remembered sets of the regions in the collection
812 // set in the event of an evacuation failure.
813 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
814
815 // After a collection pause, make the regions in the CS into free
816 // regions.
817 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
818
819 // Abandon the current collection set without recording policy
820 // statistics or updating free lists.
821 void abandon_collection_set(HeapRegion* cs_head);
822
823 // Applies "scan_non_heap_roots" to roots outside the heap,
824 // "scan_rs" to roots inside the heap (having done "set_region" to
825 // indicate the region in which the root resides),
826 // and does "scan_metadata" If "scan_rs" is
827 // NULL, then this step is skipped. The "worker_i"
828 // param is for use with parallel roots processing, and should be
829 // the "i" of the calling parallel worker thread's work(i) function.
830 // In the sequential case this param will be ignored.
831 void g1_process_strong_roots(bool is_scavenging,
832 ScanningOption so,
833 OopClosure* scan_non_heap_roots,
834 OopsInHeapRegionClosure* scan_rs,
835 G1KlassScanClosure* scan_klasses,
836 uint worker_i);
837
838 // Notifies all the necessary spaces that the committed space has
839 // been updated (either expanded or shrunk). It should be called
840 // after _g1_storage is updated.
841 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
842
843 // The concurrent marker (and the thread it runs in.)
844 ConcurrentMark* _cm;
845 ConcurrentMarkThread* _cmThread;
846 bool _mark_in_progress;
847
848 // The concurrent refiner.
849 ConcurrentG1Refine* _cg1r;
850
851 // The parallel task queues
852 RefToScanQueueSet *_task_queues;
853
854 // True iff a evacuation has failed in the current collection.
855 bool _evacuation_failed;
856
857 EvacuationFailedInfo* _evacuation_failed_info_array;
858
859 // Failed evacuations cause some logical from-space objects to have
860 // forwarding pointers to themselves. Reset them.
861 void remove_self_forwarding_pointers();
862
863 // Together, these store an object with a preserved mark, and its mark value.
864 Stack<oop, mtGC> _objs_with_preserved_marks;
865 Stack<markOop, mtGC> _preserved_marks_of_objs;
866
867 // Preserve the mark of "obj", if necessary, in preparation for its mark
868 // word being overwritten with a self-forwarding-pointer.
869 void preserve_mark_if_necessary(oop obj, markOop m);
870
871 // The stack of evac-failure objects left to be scanned.
872 GrowableArray<oop>* _evac_failure_scan_stack;
873 // The closure to apply to evac-failure objects.
874
875 OopsInHeapRegionClosure* _evac_failure_closure;
876 // Set the field above.
877 void
878 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
879 _evac_failure_closure = evac_failure_closure;
880 }
881
882 // Push "obj" on the scan stack.
883 void push_on_evac_failure_scan_stack(oop obj);
884 // Process scan stack entries until the stack is empty.
885 void drain_evac_failure_scan_stack();
886 // True iff an invocation of "drain_scan_stack" is in progress; to
887 // prevent unnecessary recursion.
888 bool _drain_in_progress;
889
890 // Do any necessary initialization for evacuation-failure handling.
891 // "cl" is the closure that will be used to process evac-failure
892 // objects.
893 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
894 // Do any necessary cleanup for evacuation-failure handling data
895 // structures.
896 void finalize_for_evac_failure();
897
898 // An attempt to evacuate "obj" has failed; take necessary steps.
899 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
900 void handle_evacuation_failure_common(oop obj, markOop m);
901
902 #ifndef PRODUCT
903 // Support for forcing evacuation failures. Analogous to
904 // PromotionFailureALot for the other collectors.
905
906 // Records whether G1EvacuationFailureALot should be in effect
907 // for the current GC
908 bool _evacuation_failure_alot_for_current_gc;
909
910 // Used to record the GC number for interval checking when
911 // determining whether G1EvaucationFailureALot is in effect
912 // for the current GC.
913 size_t _evacuation_failure_alot_gc_number;
914
915 // Count of the number of evacuations between failures.
916 volatile size_t _evacuation_failure_alot_count;
917
918 // Set whether G1EvacuationFailureALot should be in effect
919 // for the current GC (based upon the type of GC and which
920 // command line flags are set);
921 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
922 bool during_initial_mark,
923 bool during_marking);
924
925 inline void set_evacuation_failure_alot_for_current_gc();
926
927 // Return true if it's time to cause an evacuation failure.
928 inline bool evacuation_should_fail();
929
930 // Reset the G1EvacuationFailureALot counters. Should be called at
931 // the end of an evacuation pause in which an evacuation failure occurred.
932 inline void reset_evacuation_should_fail();
933 #endif // !PRODUCT
934
935 // ("Weak") Reference processing support.
936 //
937 // G1 has 2 instances of the reference processor class. One
938 // (_ref_processor_cm) handles reference object discovery
939 // and subsequent processing during concurrent marking cycles.
940 //
941 // The other (_ref_processor_stw) handles reference object
942 // discovery and processing during full GCs and incremental
943 // evacuation pauses.
944 //
945 // During an incremental pause, reference discovery will be
946 // temporarily disabled for _ref_processor_cm and will be
947 // enabled for _ref_processor_stw. At the end of the evacuation
948 // pause references discovered by _ref_processor_stw will be
949 // processed and discovery will be disabled. The previous
950 // setting for reference object discovery for _ref_processor_cm
951 // will be re-instated.
952 //
953 // At the start of marking:
954 // * Discovery by the CM ref processor is verified to be inactive
955 // and it's discovered lists are empty.
956 // * Discovery by the CM ref processor is then enabled.
957 //
958 // At the end of marking:
959 // * Any references on the CM ref processor's discovered
960 // lists are processed (possibly MT).
961 //
962 // At the start of full GC we:
963 // * Disable discovery by the CM ref processor and
964 // empty CM ref processor's discovered lists
965 // (without processing any entries).
966 // * Verify that the STW ref processor is inactive and it's
967 // discovered lists are empty.
968 // * Temporarily set STW ref processor discovery as single threaded.
969 // * Temporarily clear the STW ref processor's _is_alive_non_header
970 // field.
971 // * Finally enable discovery by the STW ref processor.
972 //
973 // The STW ref processor is used to record any discovered
974 // references during the full GC.
975 //
976 // At the end of a full GC we:
977 // * Enqueue any reference objects discovered by the STW ref processor
978 // that have non-live referents. This has the side-effect of
979 // making the STW ref processor inactive by disabling discovery.
980 // * Verify that the CM ref processor is still inactive
981 // and no references have been placed on it's discovered
982 // lists (also checked as a precondition during initial marking).
983
984 // The (stw) reference processor...
985 ReferenceProcessor* _ref_processor_stw;
986
987 STWGCTimer* _gc_timer_stw;
988 ConcurrentGCTimer* _gc_timer_cm;
989
990 G1OldTracer* _gc_tracer_cm;
991 G1NewTracer* _gc_tracer_stw;
992
993 // During reference object discovery, the _is_alive_non_header
994 // closure (if non-null) is applied to the referent object to
995 // determine whether the referent is live. If so then the
996 // reference object does not need to be 'discovered' and can
997 // be treated as a regular oop. This has the benefit of reducing
998 // the number of 'discovered' reference objects that need to
999 // be processed.
1000 //
1001 // Instance of the is_alive closure for embedding into the
1002 // STW reference processor as the _is_alive_non_header field.
1003 // Supplying a value for the _is_alive_non_header field is
1004 // optional but doing so prevents unnecessary additions to
1005 // the discovered lists during reference discovery.
1006 G1STWIsAliveClosure _is_alive_closure_stw;
1007
1008 // The (concurrent marking) reference processor...
1009 ReferenceProcessor* _ref_processor_cm;
1010
1011 // Instance of the concurrent mark is_alive closure for embedding
1012 // into the Concurrent Marking reference processor as the
1013 // _is_alive_non_header field. Supplying a value for the
1014 // _is_alive_non_header field is optional but doing so prevents
1015 // unnecessary additions to the discovered lists during reference
1016 // discovery.
1017 G1CMIsAliveClosure _is_alive_closure_cm;
1018
1019 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1020 HeapRegion** _worker_cset_start_region;
1021
1022 // Time stamp to validate the regions recorded in the cache
1023 // used by G1CollectedHeap::start_cset_region_for_worker().
1024 // The heap region entry for a given worker is valid iff
1025 // the associated time stamp value matches the current value
1026 // of G1CollectedHeap::_gc_time_stamp.
1027 unsigned int* _worker_cset_start_region_time_stamp;
1028
1029 enum G1H_process_strong_roots_tasks {
1030 G1H_PS_filter_satb_buffers,
1031 G1H_PS_refProcessor_oops_do,
1032 // Leave this one last.
1033 G1H_PS_NumElements
1034 };
1035
1036 SubTasksDone* _process_strong_tasks;
1037
1038 volatile bool _free_regions_coming;
1039
1040 public:
1041
1042 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1043
1044 void set_refine_cte_cl_concurrency(bool concurrent);
1045
1046 RefToScanQueue *task_queue(int i) const;
1047
1048 // A set of cards where updates happened during the GC
1049 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1050
1051 // A DirtyCardQueueSet that is used to hold cards that contain
1052 // references into the current collection set. This is used to
1053 // update the remembered sets of the regions in the collection
1054 // set in the event of an evacuation failure.
1055 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1056 { return _into_cset_dirty_card_queue_set; }
1057
1058 // Create a G1CollectedHeap with the specified policy.
1059 // Must call the initialize method afterwards.
1060 // May not return if something goes wrong.
1061 G1CollectedHeap(G1CollectorPolicy* policy);
1062
1063 // Initialize the G1CollectedHeap to have the initial and
1064 // maximum sizes and remembered and barrier sets
1065 // specified by the policy object.
1066 jint initialize();
1067
1068 // Return the (conservative) maximum heap alignment for any G1 heap
1069 static size_t conservative_max_heap_alignment();
1070
1071 // Initialize weak reference processing.
1072 virtual void ref_processing_init();
1073
1074 void set_par_threads(uint t) {
1075 SharedHeap::set_par_threads(t);
1076 // Done in SharedHeap but oddly there are
1077 // two _process_strong_tasks's in a G1CollectedHeap
1078 // so do it here too.
1079 _process_strong_tasks->set_n_threads(t);
1080 }
1081
1082 // Set _n_par_threads according to a policy TBD.
1083 void set_par_threads();
1084
1085 void set_n_termination(int t) {
1086 _process_strong_tasks->set_n_threads(t);
1087 }
1088
1089 virtual CollectedHeap::Name kind() const {
1090 return CollectedHeap::G1CollectedHeap;
1091 }
1092
1093 // The current policy object for the collector.
1094 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1095
1096 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1097
1098 // Adaptive size policy. No such thing for g1.
1099 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1100
1101 // The rem set and barrier set.
1102 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1103
1104 unsigned get_gc_time_stamp() {
1105 return _gc_time_stamp;
1106 }
1107
1108 void reset_gc_time_stamp() {
1109 _gc_time_stamp = 0;
1110 OrderAccess::fence();
1111 // Clear the cached CSet starting regions and time stamps.
1112 // Their validity is dependent on the GC timestamp.
1113 clear_cset_start_regions();
1114 }
1115
1116 void check_gc_time_stamps() PRODUCT_RETURN;
1117
1118 void increment_gc_time_stamp() {
1119 ++_gc_time_stamp;
1120 OrderAccess::fence();
1121 }
1122
1123 // Reset the given region's GC timestamp. If it's starts humongous,
1124 // also reset the GC timestamp of its corresponding
1125 // continues humongous regions too.
1126 void reset_gc_time_stamps(HeapRegion* hr);
1127
1128 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1129 DirtyCardQueue* into_cset_dcq,
1130 bool concurrent, uint worker_i);
1131
1132 // The shared block offset table array.
1133 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1134
1135 // Reference Processing accessors
1136
1137 // The STW reference processor....
1138 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1139
1140 // The Concurrent Marking reference processor...
1141 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1142
1143 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1144 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1145
1146 virtual size_t capacity() const;
1147 virtual size_t used() const;
1148 // This should be called when we're not holding the heap lock. The
1149 // result might be a bit inaccurate.
1150 size_t used_unlocked() const;
1151 size_t recalculate_used() const;
1152
1153 // These virtual functions do the actual allocation.
1154 // Some heaps may offer a contiguous region for shared non-blocking
1155 // allocation, via inlined code (by exporting the address of the top and
1156 // end fields defining the extent of the contiguous allocation region.)
1157 // But G1CollectedHeap doesn't yet support this.
1158
1159 virtual bool is_maximal_no_gc() const {
1160 return _g1_storage.uncommitted_size() == 0;
1161 }
1162
1163 // The total number of regions in the heap.
1164 uint n_regions() { return _hrs.length(); }
1165
1166 // The max number of regions in the heap.
1167 uint max_regions() { return _hrs.max_length(); }
1168
1169 // The number of regions that are completely free.
1170 uint free_regions() { return _free_list.length(); }
1171
1172 // The number of regions that are not completely free.
1173 uint used_regions() { return n_regions() - free_regions(); }
1174
1175 // The number of regions available for "regular" expansion.
1176 uint expansion_regions() { return _expansion_regions; }
1177
1178 // Factory method for HeapRegion instances. It will return NULL if
1179 // the allocation fails.
1180 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1181
1182 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1183 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1184 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1185 void verify_dirty_young_regions() PRODUCT_RETURN;
1186
1187 // verify_region_sets() performs verification over the region
1188 // lists. It will be compiled in the product code to be used when
1189 // necessary (i.e., during heap verification).
1190 void verify_region_sets();
1191
1192 // verify_region_sets_optional() is planted in the code for
1193 // list verification in non-product builds (and it can be enabled in
1194 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1195 #if HEAP_REGION_SET_FORCE_VERIFY
1196 void verify_region_sets_optional() {
1197 verify_region_sets();
1198 }
1199 #else // HEAP_REGION_SET_FORCE_VERIFY
1200 void verify_region_sets_optional() { }
1201 #endif // HEAP_REGION_SET_FORCE_VERIFY
1202
1203 #ifdef ASSERT
1204 bool is_on_master_free_list(HeapRegion* hr) {
1205 return hr->containing_set() == &_free_list;
1206 }
1207 #endif // ASSERT
1208
1209 // Wrapper for the region list operations that can be called from
1210 // methods outside this class.
1211
1212 void secondary_free_list_add(FreeRegionList* list) {
1213 _secondary_free_list.add_ordered(list);
1214 }
1215
1216 void append_secondary_free_list() {
1217 _free_list.add_ordered(&_secondary_free_list);
1218 }
1219
1220 void append_secondary_free_list_if_not_empty_with_lock() {
1221 // If the secondary free list looks empty there's no reason to
1222 // take the lock and then try to append it.
1223 if (!_secondary_free_list.is_empty()) {
1224 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1225 append_secondary_free_list();
1226 }
1227 }
1228
1229 inline void old_set_remove(HeapRegion* hr);
1230
1231 size_t non_young_capacity_bytes() {
1232 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1233 }
1234
1235 void set_free_regions_coming();
1236 void reset_free_regions_coming();
1237 bool free_regions_coming() { return _free_regions_coming; }
1238 void wait_while_free_regions_coming();
1239
1240 // Determine whether the given region is one that we are using as an
1241 // old GC alloc region.
1242 bool is_old_gc_alloc_region(HeapRegion* hr) {
1243 return hr == _retained_old_gc_alloc_region;
1244 }
1245
1246 // Perform a collection of the heap; intended for use in implementing
1247 // "System.gc". This probably implies as full a collection as the
1248 // "CollectedHeap" supports.
1249 virtual void collect(GCCause::Cause cause);
1250
1251 // The same as above but assume that the caller holds the Heap_lock.
1252 void collect_locked(GCCause::Cause cause);
1253
1254 // True iff an evacuation has failed in the most-recent collection.
1255 bool evacuation_failed() { return _evacuation_failed; }
1256
1257 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1258 void prepend_to_freelist(FreeRegionList* list);
1259 void decrement_summary_bytes(size_t bytes);
1260
1261 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1262 virtual bool is_in(const void* p) const;
1263
1264 // Return "TRUE" iff the given object address is within the collection
1265 // set.
1266 inline bool obj_in_cs(oop obj);
1267
1268 // Return "TRUE" iff the given object address is in the reserved
1269 // region of g1.
1270 bool is_in_g1_reserved(const void* p) const {
1271 return _g1_reserved.contains(p);
1272 }
1273
1274 // Returns a MemRegion that corresponds to the space that has been
1275 // reserved for the heap
1276 MemRegion g1_reserved() {
1277 return _g1_reserved;
1278 }
1279
1280 // Returns a MemRegion that corresponds to the space that has been
1281 // committed in the heap
1282 MemRegion g1_committed() {
1283 return _g1_committed;
1284 }
1285
1286 virtual bool is_in_closed_subset(const void* p) const;
1287
1288 G1SATBCardTableModRefBS* g1_barrier_set() {
1289 return (G1SATBCardTableModRefBS*) barrier_set();
1290 }
1291
1292 // This resets the card table to all zeros. It is used after
1293 // a collection pause which used the card table to claim cards.
1294 void cleanUpCardTable();
1295
1296 // Iteration functions.
1297
1298 // Iterate over all the ref-containing fields of all objects, calling
1299 // "cl.do_oop" on each.
1300 virtual void oop_iterate(ExtendedOopClosure* cl);
1301
1302 // Same as above, restricted to a memory region.
1303 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1304
1305 // Iterate over all objects, calling "cl.do_object" on each.
1306 virtual void object_iterate(ObjectClosure* cl);
1307
1308 virtual void safe_object_iterate(ObjectClosure* cl) {
1309 object_iterate(cl);
1310 }
1311
1312 // Iterate over all spaces in use in the heap, in ascending address order.
1313 virtual void space_iterate(SpaceClosure* cl);
1314
1315 // Iterate over heap regions, in address order, terminating the
1316 // iteration early if the "doHeapRegion" method returns "true".
1317 void heap_region_iterate(HeapRegionClosure* blk) const;
1318
1319 // Return the region with the given index. It assumes the index is valid.
1320 inline HeapRegion* region_at(uint index) const;
1321
1322 // Divide the heap region sequence into "chunks" of some size (the number
1323 // of regions divided by the number of parallel threads times some
1324 // overpartition factor, currently 4). Assumes that this will be called
1325 // in parallel by ParallelGCThreads worker threads with distinct worker
1326 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1327 // calls will use the same "claim_value", and that that claim value is
1328 // different from the claim_value of any heap region before the start of
1329 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1330 // attempting to claim the first region in each chunk, and, if
1331 // successful, applying the closure to each region in the chunk (and
1332 // setting the claim value of the second and subsequent regions of the
1333 // chunk.) For now requires that "doHeapRegion" always returns "false",
1334 // i.e., that a closure never attempt to abort a traversal.
1335 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1336 uint worker,
1337 uint no_of_par_workers,
1338 jint claim_value);
1339
1340 // It resets all the region claim values to the default.
1341 void reset_heap_region_claim_values();
1342
1343 // Resets the claim values of regions in the current
1344 // collection set to the default.
1345 void reset_cset_heap_region_claim_values();
1346
1347 #ifdef ASSERT
1348 bool check_heap_region_claim_values(jint claim_value);
1349
1350 // Same as the routine above but only checks regions in the
1351 // current collection set.
1352 bool check_cset_heap_region_claim_values(jint claim_value);
1353 #endif // ASSERT
1354
1355 // Clear the cached cset start regions and (more importantly)
1356 // the time stamps. Called when we reset the GC time stamp.
1357 void clear_cset_start_regions();
1358
1359 // Given the id of a worker, obtain or calculate a suitable
1360 // starting region for iterating over the current collection set.
1361 HeapRegion* start_cset_region_for_worker(uint worker_i);
1362
1363 // This is a convenience method that is used by the
1364 // HeapRegionIterator classes to calculate the starting region for
1365 // each worker so that they do not all start from the same region.
1366 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1367
1368 // Iterate over the regions (if any) in the current collection set.
1369 void collection_set_iterate(HeapRegionClosure* blk);
1370
1371 // As above but starting from region r
1372 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1373
1374 // Returns the first (lowest address) compactible space in the heap.
1375 virtual CompactibleSpace* first_compactible_space();
1376
1377 // A CollectedHeap will contain some number of spaces. This finds the
1378 // space containing a given address, or else returns NULL.
1379 virtual Space* space_containing(const void* addr) const;
1380
1381 // A G1CollectedHeap will contain some number of heap regions. This
1382 // finds the region containing a given address, or else returns NULL.
1383 template <class T>
1384 inline HeapRegion* heap_region_containing(const T addr) const;
1385
1386 // Like the above, but requires "addr" to be in the heap (to avoid a
1387 // null-check), and unlike the above, may return an continuing humongous
1388 // region.
1389 template <class T>
1390 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1391
1392 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1393 // each address in the (reserved) heap is a member of exactly
1394 // one block. The defining characteristic of a block is that it is
1395 // possible to find its size, and thus to progress forward to the next
1396 // block. (Blocks may be of different sizes.) Thus, blocks may
1397 // represent Java objects, or they might be free blocks in a
1398 // free-list-based heap (or subheap), as long as the two kinds are
1399 // distinguishable and the size of each is determinable.
1400
1401 // Returns the address of the start of the "block" that contains the
1402 // address "addr". We say "blocks" instead of "object" since some heaps
1403 // may not pack objects densely; a chunk may either be an object or a
1404 // non-object.
1405 virtual HeapWord* block_start(const void* addr) const;
1406
1407 // Requires "addr" to be the start of a chunk, and returns its size.
1408 // "addr + size" is required to be the start of a new chunk, or the end
1409 // of the active area of the heap.
1410 virtual size_t block_size(const HeapWord* addr) const;
1411
1412 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1413 // the block is an object.
1414 virtual bool block_is_obj(const HeapWord* addr) const;
1415
1416 // Does this heap support heap inspection? (+PrintClassHistogram)
1417 virtual bool supports_heap_inspection() const { return true; }
1418
1419 // Section on thread-local allocation buffers (TLABs)
1420 // See CollectedHeap for semantics.
1421
1422 bool supports_tlab_allocation() const;
1423 size_t tlab_capacity(Thread* ignored) const;
1424 size_t tlab_used(Thread* ignored) const;
1425 size_t max_tlab_size() const;
1426 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1427
1428 // Can a compiler initialize a new object without store barriers?
1429 // This permission only extends from the creation of a new object
1430 // via a TLAB up to the first subsequent safepoint. If such permission
1431 // is granted for this heap type, the compiler promises to call
1432 // defer_store_barrier() below on any slow path allocation of
1433 // a new object for which such initializing store barriers will
1434 // have been elided. G1, like CMS, allows this, but should be
1435 // ready to provide a compensating write barrier as necessary
1436 // if that storage came out of a non-young region. The efficiency
1437 // of this implementation depends crucially on being able to
1438 // answer very efficiently in constant time whether a piece of
1439 // storage in the heap comes from a young region or not.
1440 // See ReduceInitialCardMarks.
1441 virtual bool can_elide_tlab_store_barriers() const {
1442 return true;
1443 }
1444
1445 virtual bool card_mark_must_follow_store() const {
1446 return true;
1447 }
1448
1449 inline bool is_in_young(const oop obj);
1450
1451 #ifdef ASSERT
1452 virtual bool is_in_partial_collection(const void* p);
1453 #endif
1454
1455 virtual bool is_scavengable(const void* addr);
1456
1457 // We don't need barriers for initializing stores to objects
1458 // in the young gen: for the SATB pre-barrier, there is no
1459 // pre-value that needs to be remembered; for the remembered-set
1460 // update logging post-barrier, we don't maintain remembered set
1461 // information for young gen objects.
1462 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1463
1464 // Returns "true" iff the given word_size is "very large".
1465 static bool isHumongous(size_t word_size) {
1466 // Note this has to be strictly greater-than as the TLABs
1467 // are capped at the humongous threshold and we want to
1468 // ensure that we don't try to allocate a TLAB as
1469 // humongous and that we don't allocate a humongous
1470 // object in a TLAB.
1471 return word_size > _humongous_object_threshold_in_words;
1472 }
1473
1474 // Update mod union table with the set of dirty cards.
1475 void updateModUnion();
1476
1477 // Set the mod union bits corresponding to the given memRegion. Note
1478 // that this is always a safe operation, since it doesn't clear any
1479 // bits.
1480 void markModUnionRange(MemRegion mr);
1481
1482 // Records the fact that a marking phase is no longer in progress.
1483 void set_marking_complete() {
1484 _mark_in_progress = false;
1485 }
1486 void set_marking_started() {
1487 _mark_in_progress = true;
1488 }
1489 bool mark_in_progress() {
1490 return _mark_in_progress;
1491 }
1492
1493 // Print the maximum heap capacity.
1494 virtual size_t max_capacity() const;
1495
1496 virtual jlong millis_since_last_gc();
1497
1498
1499 // Convenience function to be used in situations where the heap type can be
1500 // asserted to be this type.
1501 static G1CollectedHeap* heap();
1502
1503 void set_region_short_lived_locked(HeapRegion* hr);
1504 // add appropriate methods for any other surv rate groups
1505
1506 YoungList* young_list() const { return _young_list; }
1507
1508 // debugging
1509 bool check_young_list_well_formed() {
1510 return _young_list->check_list_well_formed();
1511 }
1512
1513 bool check_young_list_empty(bool check_heap,
1514 bool check_sample = true);
1515
1516 // *** Stuff related to concurrent marking. It's not clear to me that so
1517 // many of these need to be public.
1518
1519 // The functions below are helper functions that a subclass of
1520 // "CollectedHeap" can use in the implementation of its virtual
1521 // functions.
1522 // This performs a concurrent marking of the live objects in a
1523 // bitmap off to the side.
1524 void doConcurrentMark();
1525
1526 bool isMarkedPrev(oop obj) const;
1527 bool isMarkedNext(oop obj) const;
1528
1529 // Determine if an object is dead, given the object and also
1530 // the region to which the object belongs. An object is dead
1531 // iff a) it was not allocated since the last mark and b) it
1532 // is not marked.
1533
1534 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1535 return
1536 !hr->obj_allocated_since_prev_marking(obj) &&
1537 !isMarkedPrev(obj);
1538 }
1539
1540 // This function returns true when an object has been
1541 // around since the previous marking and hasn't yet
1542 // been marked during this marking.
1543
1544 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1545 return
1546 !hr->obj_allocated_since_next_marking(obj) &&
1547 !isMarkedNext(obj);
1548 }
1549
1550 // Determine if an object is dead, given only the object itself.
1551 // This will find the region to which the object belongs and
1552 // then call the region version of the same function.
1553
1554 // Added if it is NULL it isn't dead.
1555
1556 inline bool is_obj_dead(const oop obj) const;
1557
1558 inline bool is_obj_ill(const oop obj) const;
1559
1560 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1561 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1562 bool is_marked(oop obj, VerifyOption vo);
1563 const char* top_at_mark_start_str(VerifyOption vo);
1564
1565 ConcurrentMark* concurrent_mark() const { return _cm; }
1566
1567 // Refinement
1568
1569 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1570
1571 // The dirty cards region list is used to record a subset of regions
1572 // whose cards need clearing. The list if populated during the
1573 // remembered set scanning and drained during the card table
1574 // cleanup. Although the methods are reentrant, population/draining
1575 // phases must not overlap. For synchronization purposes the last
1576 // element on the list points to itself.
1577 HeapRegion* _dirty_cards_region_list;
1578 void push_dirty_cards_region(HeapRegion* hr);
1579 HeapRegion* pop_dirty_cards_region();
1580
1581 // Optimized nmethod scanning support routines
1582
1583 // Register the given nmethod with the G1 heap.
1584 virtual void register_nmethod(nmethod* nm);
1585
1586 // Unregister the given nmethod from the G1 heap.
1587 virtual void unregister_nmethod(nmethod* nm);
1588
1589 // Migrate the nmethods in the code root lists of the regions
1590 // in the collection set to regions in to-space. In the event
1591 // of an evacuation failure, nmethods that reference objects
1592 // that were not successfully evacuated are not migrated.
1593 void migrate_strong_code_roots();
1594
1595 // Free up superfluous code root memory.
1596 void purge_code_root_memory();
1597
1598 // During an initial mark pause, mark all the code roots that
1599 // point into regions *not* in the collection set.
1600 void mark_strong_code_roots(uint worker_id);
1601
1602 // Rebuild the strong code root lists for each region
1603 // after a full GC.
1604 void rebuild_strong_code_roots();
1605
1606 // Delete entries for dead interned string and clean up unreferenced symbols
1607 // in symbol table, possibly in parallel.
1608 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1609
1610 // Redirty logged cards in the refinement queue.
1611 void redirty_logged_cards();
1612 // Verification
1613
1614 // The following is just to alert the verification code
1615 // that a full collection has occurred and that the
1616 // remembered sets are no longer up to date.
1617 bool _full_collection;
1618 void set_full_collection() { _full_collection = true;}
1619 void clear_full_collection() {_full_collection = false;}
1620 bool full_collection() {return _full_collection;}
1621
1622 // Perform any cleanup actions necessary before allowing a verification.
1623 virtual void prepare_for_verify();
1624
1625 // Perform verification.
1626
1627 // vo == UsePrevMarking -> use "prev" marking information,
1628 // vo == UseNextMarking -> use "next" marking information
1629 // vo == UseMarkWord -> use the mark word in the object header
1630 //
1631 // NOTE: Only the "prev" marking information is guaranteed to be
1632 // consistent most of the time, so most calls to this should use
1633 // vo == UsePrevMarking.
1634 // Currently, there is only one case where this is called with
1635 // vo == UseNextMarking, which is to verify the "next" marking
1636 // information at the end of remark.
1637 // Currently there is only one place where this is called with
1638 // vo == UseMarkWord, which is to verify the marking during a
1639 // full GC.
1640 void verify(bool silent, VerifyOption vo);
1641
1642 // Override; it uses the "prev" marking information
1643 virtual void verify(bool silent);
1644
1645 // The methods below are here for convenience and dispatch the
1646 // appropriate method depending on value of the given VerifyOption
1647 // parameter. The values for that parameter, and their meanings,
1648 // are the same as those above.
1649
1650 bool is_obj_dead_cond(const oop obj,
1651 const HeapRegion* hr,
1652 const VerifyOption vo) const;
1653
1654 bool is_obj_dead_cond(const oop obj,
1655 const VerifyOption vo) const;
1656
1657 // Printing
1658
1659 virtual void print_on(outputStream* st) const;
1660 virtual void print_extended_on(outputStream* st) const;
1661 virtual void print_on_error(outputStream* st) const;
1662
1663 virtual void print_gc_threads_on(outputStream* st) const;
1664 virtual void gc_threads_do(ThreadClosure* tc) const;
1665
1666 // Override
1667 void print_tracing_info() const;
1668
1669 // The following two methods are helpful for debugging RSet issues.
1670 void print_cset_rsets() PRODUCT_RETURN;
1671 void print_all_rsets() PRODUCT_RETURN;
1672
1673 public:
1674 void stop_conc_gc_threads();
1675
1676 size_t pending_card_num();
1677 size_t cards_scanned();
1678
1679 protected:
1680 size_t _max_heap_capacity;
1681 };
1682
1683 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1684 private:
1685 bool _retired;
1686
1687 public:
1688 G1ParGCAllocBuffer(size_t gclab_word_size);
1689
1690 void set_buf(HeapWord* buf) {
1691 ParGCAllocBuffer::set_buf(buf);
1692 _retired = false;
1693 }
1694
1695 void retire(bool end_of_gc, bool retain) {
1696 if (_retired)
1697 return;
1698 ParGCAllocBuffer::retire(end_of_gc, retain);
1699 _retired = true;
1700 }
1701 };
1702
1703 class G1ParScanThreadState : public StackObj {
1704 protected:
1705 G1CollectedHeap* _g1h;
1706 RefToScanQueue* _refs;
1707 DirtyCardQueue _dcq;
1708 G1SATBCardTableModRefBS* _ct_bs;
1709 G1RemSet* _g1_rem;
1710
1711 G1ParGCAllocBuffer _surviving_alloc_buffer;
1712 G1ParGCAllocBuffer _tenured_alloc_buffer;
1713 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1714 ageTable _age_table;
1715
1716 G1ParScanClosure _scanner;
1717
1718 size_t _alloc_buffer_waste;
1719 size_t _undo_waste;
1720
1721 OopsInHeapRegionClosure* _evac_failure_cl;
1722
1723 int _hash_seed;
1724 uint _queue_num;
1725
1726 size_t _term_attempts;
1727
1728 double _start;
1729 double _start_strong_roots;
1730 double _strong_roots_time;
1731 double _start_term;
1732 double _term_time;
1733
1734 // Map from young-age-index (0 == not young, 1 is youngest) to
1735 // surviving words. base is what we get back from the malloc call
1736 size_t* _surviving_young_words_base;
1737 // this points into the array, as we use the first few entries for padding
1738 size_t* _surviving_young_words;
1739
1740 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1741
1742 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1743
1744 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1745
1746 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1747 G1SATBCardTableModRefBS* ctbs() { return _ct_bs; }
1748
1749 template <class T> inline void immediate_rs_update(HeapRegion* from, T* p, int tid);
1750
1751 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1752 // If the new value of the field points to the same region or
1753 // is the to-space, we don't need to include it in the Rset updates.
1754 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1755 size_t card_index = ctbs()->index_for(p);
1756 // If the card hasn't been added to the buffer, do it.
1757 if (ctbs()->mark_card_deferred(card_index)) {
1758 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1759 }
1760 }
1761 }
1762
1763 public:
1764 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp);
1765
1766 ~G1ParScanThreadState() {
1767 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1768 }
1769
1770 RefToScanQueue* refs() { return _refs; }
1771 ageTable* age_table() { return &_age_table; }
1772
1773 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1774 return _alloc_buffers[purpose];
1775 }
1776
1777 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1778 size_t undo_waste() const { return _undo_waste; }
1779
1780 #ifdef ASSERT
1781 bool verify_ref(narrowOop* ref) const;
1782 bool verify_ref(oop* ref) const;
1783 bool verify_task(StarTask ref) const;
1784 #endif // ASSERT
1785
1786 template <class T> void push_on_queue(T* ref) {
1787 assert(verify_ref(ref), "sanity");
1788 refs()->push(ref);
1789 }
1790
1791 template <class T> inline void update_rs(HeapRegion* from, T* p, int tid);
1792
1793 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1794 HeapWord* obj = NULL;
1795 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1796 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1797 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1798 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1799 alloc_buf->retire(false /* end_of_gc */, false /* retain */);
1800
1801 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1802 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1803 // Otherwise.
1804 alloc_buf->set_word_size(gclab_word_size);
1805 alloc_buf->set_buf(buf);
1806
1807 obj = alloc_buf->allocate(word_sz);
1808 assert(obj != NULL, "buffer was definitely big enough...");
1809 } else {
1810 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1811 }
1812 return obj;
1813 }
1814
1815 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1816 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1817 if (obj != NULL) return obj;
1818 return allocate_slow(purpose, word_sz);
1819 }
1820
1821 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1822 if (alloc_buffer(purpose)->contains(obj)) {
1823 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1824 "should contain whole object");
1825 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1826 } else {
1827 CollectedHeap::fill_with_object(obj, word_sz);
1828 add_to_undo_waste(word_sz);
1829 }
1830 }
1831
1832 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1833 _evac_failure_cl = evac_failure_cl;
1834 }
1835 OopsInHeapRegionClosure* evac_failure_closure() {
1836 return _evac_failure_cl;
1837 }
1838
1839 int* hash_seed() { return &_hash_seed; }
1840 uint queue_num() { return _queue_num; }
1841
1842 size_t term_attempts() const { return _term_attempts; }
1843 void note_term_attempt() { _term_attempts++; }
1844
1845 void start_strong_roots() {
1846 _start_strong_roots = os::elapsedTime();
1847 }
1848 void end_strong_roots() {
1849 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1850 }
1851 double strong_roots_time() const { return _strong_roots_time; }
1852
1853 void start_term_time() {
1854 note_term_attempt();
1855 _start_term = os::elapsedTime();
1856 }
1857 void end_term_time() {
1858 _term_time += (os::elapsedTime() - _start_term);
1859 }
1860 double term_time() const { return _term_time; }
1861
1862 double elapsed_time() const {
1863 return os::elapsedTime() - _start;
1864 }
1865
1866 static void
1867 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1868 void
1869 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1870
1871 size_t* surviving_young_words() {
1872 // We add on to hide entry 0 which accumulates surviving words for
1873 // age -1 regions (i.e. non-young ones)
1874 return _surviving_young_words;
1875 }
1876
1877 void retire_alloc_buffers() {
1878 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1879 size_t waste = _alloc_buffers[ap]->words_remaining();
1880 add_to_alloc_buffer_waste(waste);
1881 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1882 true /* end_of_gc */,
1883 false /* retain */);
1884 }
1885 }
1886 private:
1887 #define G1_PARTIAL_ARRAY_MASK 0x2
1888
1889 inline bool has_partial_array_mask(oop* ref) const {
1890 return ((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) == G1_PARTIAL_ARRAY_MASK;
1891 }
1892
1893 // We never encode partial array oops as narrowOop*, so return false immediately.
1894 // This allows the compiler to create optimized code when popping references from
1895 // the work queue.
1896 inline bool has_partial_array_mask(narrowOop* ref) const {
1897 assert(((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) != G1_PARTIAL_ARRAY_MASK, "Partial array oop reference encoded as narrowOop*");
1898 return false;
1899 }
1900
1901 // Only implement set_partial_array_mask() for regular oops, not for narrowOops.
1902 // We always encode partial arrays as regular oop, to allow the
1903 // specialization for has_partial_array_mask() for narrowOops above.
1904 // This means that unintentional use of this method with narrowOops are caught
1905 // by the compiler.
1906 inline oop* set_partial_array_mask(oop obj) const {
1907 assert(((uintptr_t)(void *)obj & G1_PARTIAL_ARRAY_MASK) == 0, "Information loss!");
1908 return (oop*) ((uintptr_t)(void *)obj | G1_PARTIAL_ARRAY_MASK);
1909 }
1910
1911 inline oop clear_partial_array_mask(oop* ref) const {
1912 return cast_to_oop((intptr_t)ref & ~G1_PARTIAL_ARRAY_MASK);
1913 }
1914
1915 inline void do_oop_partial_array(oop* p);
1916
1917 // This method is applied to the fields of the objects that have just been copied.
1918 template <class T> void do_oop_evac(T* p, HeapRegion* from) {
1919 assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
1920 "Reference should not be NULL here as such are never pushed to the task queue.");
1921 oop obj = oopDesc::load_decode_heap_oop_not_null(p);
1922
1923 // Although we never intentionally push references outside of the collection
1924 // set, due to (benign) races in the claim mechanism during RSet scanning more
1925 // than one thread might claim the same card. So the same card may be
1926 // processed multiple times. So redo this check.
1927 if (_g1h->in_cset_fast_test(obj)) {
1928 oop forwardee;
1929 if (obj->is_forwarded()) {
1930 forwardee = obj->forwardee();
1931 } else {
1932 forwardee = copy_to_survivor_space(obj);
1933 }
1934 assert(forwardee != NULL, "forwardee should not be NULL");
1935 oopDesc::encode_store_heap_oop(p, forwardee);
1936 }
1937
1938 assert(obj != NULL, "Must be");
1939 update_rs(from, p, queue_num());
1940 }
1941 public:
1942
1943 oop copy_to_survivor_space(oop const obj);
1944
1945 template <class T> inline void deal_with_reference(T* ref_to_scan);
1946
1947 inline void deal_with_reference(StarTask ref);
1948
1949 public:
1950 void trim_queue();
1951 };
1952
1953 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP