1 /*
2 * Copyright (c) 2001, 2012, 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.
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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).
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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/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
40 #include "utilities/stack.hpp"
41
42 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
43 // It uses the "Garbage First" heap organization and algorithm, which
44 // may combine concurrent marking with parallel, incremental compaction of
45 // heap subsets that will yield large amounts of garbage.
46
47 class HeapRegion;
48 class HRRSCleanupTask;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1KlassScanClosure;
52 class G1ScanHeapEvacClosure;
53 class ObjectClosure;
54 class SpaceClosure;
55 class CompactibleSpaceClosure;
56 class Space;
57 class G1CollectorPolicy;
58 class GenRemSet;
59 class G1RemSet;
60 class HeapRegionRemSetIterator;
61 class ConcurrentMark;
62 class ConcurrentMarkThread;
63 class ConcurrentG1Refine;
64 class GenerationCounters;
65
66 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
67 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
68
69 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
70 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71
72 enum GCAllocPurpose {
73 GCAllocForTenured,
74 GCAllocForSurvived,
75 GCAllocPurposeCount
76 };
77
78 class YoungList : public CHeapObj<mtGC> {
79 private:
80 G1CollectedHeap* _g1h;
81
82 HeapRegion* _head;
83
84 HeapRegion* _survivor_head;
85 HeapRegion* _survivor_tail;
86
87 HeapRegion* _curr;
88
89 uint _length;
90 uint _survivor_length;
91
92 size_t _last_sampled_rs_lengths;
93 size_t _sampled_rs_lengths;
94
95 void empty_list(HeapRegion* list);
96
97 public:
98 YoungList(G1CollectedHeap* g1h);
99
100 void push_region(HeapRegion* hr);
101 void add_survivor_region(HeapRegion* hr);
102
103 void empty_list();
104 bool is_empty() { return _length == 0; }
105 uint length() { return _length; }
106 uint survivor_length() { return _survivor_length; }
107
108 // Currently we do not keep track of the used byte sum for the
109 // young list and the survivors and it'd be quite a lot of work to
110 // do so. When we'll eventually replace the young list with
111 // instances of HeapRegionLinkedList we'll get that for free. So,
112 // we'll report the more accurate information then.
113 size_t eden_used_bytes() {
114 assert(length() >= survivor_length(), "invariant");
115 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
116 }
117 size_t survivor_used_bytes() {
118 return (size_t) survivor_length() * HeapRegion::GrainBytes;
119 }
120
121 void rs_length_sampling_init();
122 bool rs_length_sampling_more();
123 void rs_length_sampling_next();
124
125 void reset_sampled_info() {
126 _last_sampled_rs_lengths = 0;
127 }
128 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
129
130 // for development purposes
131 void reset_auxilary_lists();
132 void clear() { _head = NULL; _length = 0; }
133
134 void clear_survivors() {
135 _survivor_head = NULL;
136 _survivor_tail = NULL;
137 _survivor_length = 0;
138 }
139
140 HeapRegion* first_region() { return _head; }
141 HeapRegion* first_survivor_region() { return _survivor_head; }
142 HeapRegion* last_survivor_region() { return _survivor_tail; }
143
144 // debugging
145 bool check_list_well_formed();
146 bool check_list_empty(bool check_sample = true);
147 void print();
148 };
149
150 class MutatorAllocRegion : public G1AllocRegion {
151 protected:
152 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
153 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
154 public:
155 MutatorAllocRegion()
156 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
157 };
158
159 // The G1 STW is alive closure.
160 // An instance is embedded into the G1CH and used as the
161 // (optional) _is_alive_non_header closure in the STW
162 // reference processor. It is also extensively used during
163 // refence processing during STW evacuation pauses.
164 class G1STWIsAliveClosure: public BoolObjectClosure {
165 G1CollectedHeap* _g1;
166 public:
167 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
168 void do_object(oop p) { assert(false, "Do not call."); }
169 bool do_object_b(oop p);
170 };
171
172 class SurvivorGCAllocRegion : public G1AllocRegion {
173 protected:
174 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
175 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
176 public:
177 SurvivorGCAllocRegion()
178 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
179 };
180
181 class OldGCAllocRegion : public G1AllocRegion {
182 protected:
183 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
184 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
185 public:
186 OldGCAllocRegion()
187 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
188 };
189
190 class RefineCardTableEntryClosure;
191
192 class G1CollectedHeap : public SharedHeap {
193 friend class VM_G1CollectForAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
200
201 // Closures used in implementation.
202 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
203 friend class G1ParCopyClosure;
204 friend class G1IsAliveClosure;
205 friend class G1EvacuateFollowersClosure;
206 friend class G1ParScanThreadState;
207 friend class G1ParScanClosureSuper;
208 friend class G1ParEvacuateFollowersClosure;
209 friend class G1ParTask;
210 friend class G1FreeGarbageRegionClosure;
211 friend class RefineCardTableEntryClosure;
212 friend class G1PrepareCompactClosure;
213 friend class RegionSorter;
214 friend class RegionResetter;
215 friend class CountRCClosure;
216 friend class EvacPopObjClosure;
217 friend class G1ParCleanupCTTask;
218
219 // Other related classes.
220 friend class G1MarkSweep;
221
222 private:
223 // The one and only G1CollectedHeap, so static functions can find it.
224 static G1CollectedHeap* _g1h;
225
226 static size_t _humongous_object_threshold_in_words;
227
228 // Storage for the G1 heap.
229 VirtualSpace _g1_storage;
230 MemRegion _g1_reserved;
231
232 // The part of _g1_storage that is currently committed.
233 MemRegion _g1_committed;
234
235 // The master free list. It will satisfy all new region allocations.
236 MasterFreeRegionList _free_list;
237
238 // The secondary free list which contains regions that have been
239 // freed up during the cleanup process. This will be appended to the
240 // master free list when appropriate.
241 SecondaryFreeRegionList _secondary_free_list;
242
243 // It keeps track of the old regions.
244 MasterOldRegionSet _old_set;
245
246 // It keeps track of the humongous regions.
247 MasterHumongousRegionSet _humongous_set;
248
249 // The number of regions we could create by expansion.
250 uint _expansion_regions;
251
252 // The block offset table for the G1 heap.
253 G1BlockOffsetSharedArray* _bot_shared;
254
255 // Tears down the region sets / lists so that they are empty and the
256 // regions on the heap do not belong to a region set / list. The
257 // only exception is the humongous set which we leave unaltered. If
258 // free_list_only is true, it will only tear down the master free
259 // list. It is called before a Full GC (free_list_only == false) or
260 // before heap shrinking (free_list_only == true).
261 void tear_down_region_sets(bool free_list_only);
262
263 // Rebuilds the region sets / lists so that they are repopulated to
264 // reflect the contents of the heap. The only exception is the
265 // humongous set which was not torn down in the first place. If
266 // free_list_only is true, it will only rebuild the master free
267 // list. It is called after a Full GC (free_list_only == false) or
268 // after heap shrinking (free_list_only == true).
269 void rebuild_region_sets(bool free_list_only);
270
271 // The sequence of all heap regions in the heap.
272 HeapRegionSeq _hrs;
273
274 // Alloc region used to satisfy mutator allocation requests.
275 MutatorAllocRegion _mutator_alloc_region;
276
277 // Alloc region used to satisfy allocation requests by the GC for
278 // survivor objects.
279 SurvivorGCAllocRegion _survivor_gc_alloc_region;
280
281 // PLAB sizing policy for survivors.
282 PLABStats _survivor_plab_stats;
283
284 // Alloc region used to satisfy allocation requests by the GC for
285 // old objects.
286 OldGCAllocRegion _old_gc_alloc_region;
287
288 // PLAB sizing policy for tenured objects.
289 PLABStats _old_plab_stats;
290
291 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
292 PLABStats* stats = NULL;
293
294 switch (purpose) {
295 case GCAllocForSurvived:
296 stats = &_survivor_plab_stats;
297 break;
298 case GCAllocForTenured:
299 stats = &_old_plab_stats;
300 break;
301 default:
302 assert(false, "unrecognized GCAllocPurpose");
303 }
304
305 return stats;
306 }
307
308 // The last old region we allocated to during the last GC.
309 // Typically, it is not full so we should re-use it during the next GC.
310 HeapRegion* _retained_old_gc_alloc_region;
311
312 // It specifies whether we should attempt to expand the heap after a
313 // region allocation failure. If heap expansion fails we set this to
314 // false so that we don't re-attempt the heap expansion (it's likely
315 // that subsequent expansion attempts will also fail if one fails).
316 // Currently, it is only consulted during GC and it's reset at the
317 // start of each GC.
318 bool _expand_heap_after_alloc_failure;
319
320 // It resets the mutator alloc region before new allocations can take place.
321 void init_mutator_alloc_region();
322
323 // It releases the mutator alloc region.
324 void release_mutator_alloc_region();
325
326 // It initializes the GC alloc regions at the start of a GC.
327 void init_gc_alloc_regions();
328
329 // It releases the GC alloc regions at the end of a GC.
330 void release_gc_alloc_regions(uint no_of_gc_workers);
331
332 // It does any cleanup that needs to be done on the GC alloc regions
333 // before a Full GC.
334 void abandon_gc_alloc_regions();
335
336 // Helper for monitoring and management support.
337 G1MonitoringSupport* _g1mm;
338
339 // Determines PLAB size for a particular allocation purpose.
340 size_t desired_plab_sz(GCAllocPurpose purpose);
341
342 // Outside of GC pauses, the number of bytes used in all regions other
343 // than the current allocation region.
344 size_t _summary_bytes_used;
345
346 // This is used for a quick test on whether a reference points into
347 // the collection set or not. Basically, we have an array, with one
348 // byte per region, and that byte denotes whether the corresponding
349 // region is in the collection set or not. The entry corresponding
350 // the bottom of the heap, i.e., region 0, is pointed to by
351 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
352 // biased so that it actually points to address 0 of the address
353 // space, to make the test as fast as possible (we can simply shift
354 // the address to address into it, instead of having to subtract the
355 // bottom of the heap from the address before shifting it; basically
356 // it works in the same way the card table works).
357 bool* _in_cset_fast_test;
358
359 // The allocated array used for the fast test on whether a reference
360 // points into the collection set or not. This field is also used to
361 // free the array.
362 bool* _in_cset_fast_test_base;
363
364 // The length of the _in_cset_fast_test_base array.
365 uint _in_cset_fast_test_length;
366
367 volatile unsigned _gc_time_stamp;
368
369 size_t* _surviving_young_words;
370
371 G1HRPrinter _hr_printer;
372
373 void setup_surviving_young_words();
374 void update_surviving_young_words(size_t* surv_young_words);
375 void cleanup_surviving_young_words();
376
377 // It decides whether an explicit GC should start a concurrent cycle
378 // instead of doing a STW GC. Currently, a concurrent cycle is
379 // explicitly started if:
380 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
381 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
382 // (c) cause == _g1_humongous_allocation
383 bool should_do_concurrent_full_gc(GCCause::Cause cause);
384
385 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
386 // concurrent cycles) we have started.
387 volatile unsigned int _old_marking_cycles_started;
388
389 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
390 // concurrent cycles) we have completed.
391 volatile unsigned int _old_marking_cycles_completed;
392
393 // This is a non-product method that is helpful for testing. It is
394 // called at the end of a GC and artificially expands the heap by
395 // allocating a number of dead regions. This way we can induce very
396 // frequent marking cycles and stress the cleanup / concurrent
397 // cleanup code more (as all the regions that will be allocated by
398 // this method will be found dead by the marking cycle).
399 void allocate_dummy_regions() PRODUCT_RETURN;
400
401 // Clear RSets after a compaction. It also resets the GC time stamps.
402 void clear_rsets_post_compaction();
403
404 // If the HR printer is active, dump the state of the regions in the
405 // heap after a compaction.
406 void print_hrs_post_compaction();
407
408 double verify(bool guard, const char* msg);
409 void verify_before_gc();
410 void verify_after_gc();
411
412 void log_gc_header();
413 void log_gc_footer(double pause_time_sec);
414
415 // These are macros so that, if the assert fires, we get the correct
416 // line number, file, etc.
417
418 #define heap_locking_asserts_err_msg(_extra_message_) \
419 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
420 (_extra_message_), \
421 BOOL_TO_STR(Heap_lock->owned_by_self()), \
422 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
423 BOOL_TO_STR(Thread::current()->is_VM_thread()))
424
425 #define assert_heap_locked() \
426 do { \
427 assert(Heap_lock->owned_by_self(), \
428 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
429 } while (0)
430
431 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
432 do { \
433 assert(Heap_lock->owned_by_self() || \
434 (SafepointSynchronize::is_at_safepoint() && \
435 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
436 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
437 "should be at a safepoint")); \
438 } while (0)
439
440 #define assert_heap_locked_and_not_at_safepoint() \
441 do { \
442 assert(Heap_lock->owned_by_self() && \
443 !SafepointSynchronize::is_at_safepoint(), \
444 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
445 "should not be at a safepoint")); \
446 } while (0)
447
448 #define assert_heap_not_locked() \
449 do { \
450 assert(!Heap_lock->owned_by_self(), \
451 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
452 } while (0)
453
454 #define assert_heap_not_locked_and_not_at_safepoint() \
455 do { \
456 assert(!Heap_lock->owned_by_self() && \
457 !SafepointSynchronize::is_at_safepoint(), \
458 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
459 "should not be at a safepoint")); \
460 } while (0)
461
462 #define assert_at_safepoint(_should_be_vm_thread_) \
463 do { \
464 assert(SafepointSynchronize::is_at_safepoint() && \
465 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
466 heap_locking_asserts_err_msg("should be at a safepoint")); \
467 } while (0)
468
469 #define assert_not_at_safepoint() \
470 do { \
471 assert(!SafepointSynchronize::is_at_safepoint(), \
472 heap_locking_asserts_err_msg("should not be at a safepoint")); \
473 } while (0)
474
475 protected:
476
477 // The young region list.
478 YoungList* _young_list;
479
480 // The current policy object for the collector.
481 G1CollectorPolicy* _g1_policy;
482
483 // This is the second level of trying to allocate a new region. If
484 // new_region() didn't find a region on the free_list, this call will
485 // check whether there's anything available on the
486 // secondary_free_list and/or wait for more regions to appear on
487 // that list, if _free_regions_coming is set.
488 HeapRegion* new_region_try_secondary_free_list();
489
490 // Try to allocate a single non-humongous HeapRegion sufficient for
491 // an allocation of the given word_size. If do_expand is true,
492 // attempt to expand the heap if necessary to satisfy the allocation
493 // request.
494 HeapRegion* new_region(size_t word_size, bool do_expand);
495
496 // Attempt to satisfy a humongous allocation request of the given
497 // size by finding a contiguous set of free regions of num_regions
498 // length and remove them from the master free list. Return the
499 // index of the first region or G1_NULL_HRS_INDEX if the search
500 // was unsuccessful.
501 uint humongous_obj_allocate_find_first(uint num_regions,
502 size_t word_size);
503
504 // Initialize a contiguous set of free regions of length num_regions
505 // and starting at index first so that they appear as a single
506 // humongous region.
507 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
508 uint num_regions,
509 size_t word_size);
510
511 // Attempt to allocate a humongous object of the given size. Return
512 // NULL if unsuccessful.
513 HeapWord* humongous_obj_allocate(size_t word_size);
514
515 // The following two methods, allocate_new_tlab() and
516 // mem_allocate(), are the two main entry points from the runtime
517 // into the G1's allocation routines. They have the following
518 // assumptions:
519 //
520 // * They should both be called outside safepoints.
521 //
522 // * They should both be called without holding the Heap_lock.
523 //
524 // * All allocation requests for new TLABs should go to
525 // allocate_new_tlab().
526 //
527 // * All non-TLAB allocation requests should go to mem_allocate().
528 //
529 // * If either call cannot satisfy the allocation request using the
530 // current allocating region, they will try to get a new one. If
531 // this fails, they will attempt to do an evacuation pause and
532 // retry the allocation.
533 //
534 // * If all allocation attempts fail, even after trying to schedule
535 // an evacuation pause, allocate_new_tlab() will return NULL,
536 // whereas mem_allocate() will attempt a heap expansion and/or
537 // schedule a Full GC.
538 //
539 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
540 // should never be called with word_size being humongous. All
541 // humongous allocation requests should go to mem_allocate() which
542 // will satisfy them with a special path.
543
544 virtual HeapWord* allocate_new_tlab(size_t word_size);
545
546 virtual HeapWord* mem_allocate(size_t word_size,
547 bool* gc_overhead_limit_was_exceeded);
548
549 // The following three methods take a gc_count_before_ret
550 // parameter which is used to return the GC count if the method
551 // returns NULL. Given that we are required to read the GC count
552 // while holding the Heap_lock, and these paths will take the
553 // Heap_lock at some point, it's easier to get them to read the GC
554 // count while holding the Heap_lock before they return NULL instead
555 // of the caller (namely: mem_allocate()) having to also take the
556 // Heap_lock just to read the GC count.
557
558 // First-level mutator allocation attempt: try to allocate out of
559 // the mutator alloc region without taking the Heap_lock. This
560 // should only be used for non-humongous allocations.
561 inline HeapWord* attempt_allocation(size_t word_size,
562 unsigned int* gc_count_before_ret);
563
564 // Second-level mutator allocation attempt: take the Heap_lock and
565 // retry the allocation attempt, potentially scheduling a GC
566 // pause. This should only be used for non-humongous allocations.
567 HeapWord* attempt_allocation_slow(size_t word_size,
568 unsigned int* gc_count_before_ret);
569
570 // Takes the Heap_lock and attempts a humongous allocation. It can
571 // potentially schedule a GC pause.
572 HeapWord* attempt_allocation_humongous(size_t word_size,
573 unsigned int* gc_count_before_ret);
574
575 // Allocation attempt that should be called during safepoints (e.g.,
576 // at the end of a successful GC). expect_null_mutator_alloc_region
577 // specifies whether the mutator alloc region is expected to be NULL
578 // or not.
579 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
580 bool expect_null_mutator_alloc_region);
581
582 // It dirties the cards that cover the block so that so that the post
583 // write barrier never queues anything when updating objects on this
584 // block. It is assumed (and in fact we assert) that the block
585 // belongs to a young region.
586 inline void dirty_young_block(HeapWord* start, size_t word_size);
587
588 // Allocate blocks during garbage collection. Will ensure an
589 // allocation region, either by picking one or expanding the
590 // heap, and then allocate a block of the given size. The block
591 // may not be a humongous - it must fit into a single heap region.
592 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
593
594 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
595 HeapRegion* alloc_region,
596 bool par,
597 size_t word_size);
598
599 // Ensure that no further allocations can happen in "r", bearing in mind
600 // that parallel threads might be attempting allocations.
601 void par_allocate_remaining_space(HeapRegion* r);
602
603 // Allocation attempt during GC for a survivor object / PLAB.
604 inline HeapWord* survivor_attempt_allocation(size_t word_size);
605
606 // Allocation attempt during GC for an old object / PLAB.
607 inline HeapWord* old_attempt_allocation(size_t word_size);
608
609 // These methods are the "callbacks" from the G1AllocRegion class.
610
611 // For mutator alloc regions.
612 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
613 void retire_mutator_alloc_region(HeapRegion* alloc_region,
614 size_t allocated_bytes);
615
616 // For GC alloc regions.
617 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
618 GCAllocPurpose ap);
619 void retire_gc_alloc_region(HeapRegion* alloc_region,
620 size_t allocated_bytes, GCAllocPurpose ap);
621
622 // - if explicit_gc is true, the GC is for a System.gc() or a heap
623 // inspection request and should collect the entire heap
624 // - if clear_all_soft_refs is true, all soft references should be
625 // cleared during the GC
626 // - if explicit_gc is false, word_size describes the allocation that
627 // the GC should attempt (at least) to satisfy
628 // - it returns false if it is unable to do the collection due to the
629 // GC locker being active, true otherwise
630 bool do_collection(bool explicit_gc,
631 bool clear_all_soft_refs,
632 size_t word_size);
633
634 // Callback from VM_G1CollectFull operation.
635 // Perform a full collection.
636 virtual void do_full_collection(bool clear_all_soft_refs);
637
638 // Resize the heap if necessary after a full collection. If this is
639 // after a collect-for allocation, "word_size" is the allocation size,
640 // and will be considered part of the used portion of the heap.
641 void resize_if_necessary_after_full_collection(size_t word_size);
642
643 // Callback from VM_G1CollectForAllocation operation.
644 // This function does everything necessary/possible to satisfy a
645 // failed allocation request (including collection, expansion, etc.)
646 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
647
648 // Attempting to expand the heap sufficiently
649 // to support an allocation of the given "word_size". If
650 // successful, perform the allocation and return the address of the
651 // allocated block, or else "NULL".
652 HeapWord* expand_and_allocate(size_t word_size);
653
654 // Process any reference objects discovered during
655 // an incremental evacuation pause.
656 void process_discovered_references(uint no_of_gc_workers);
657
658 // Enqueue any remaining discovered references
659 // after processing.
660 void enqueue_discovered_references(uint no_of_gc_workers);
661
662 public:
663
664 G1MonitoringSupport* g1mm() {
665 assert(_g1mm != NULL, "should have been initialized");
666 return _g1mm;
667 }
668
669 // Expand the garbage-first heap by at least the given size (in bytes!).
670 // Returns true if the heap was expanded by the requested amount;
671 // false otherwise.
672 // (Rounds up to a HeapRegion boundary.)
673 bool expand(size_t expand_bytes);
674
675 // Do anything common to GC's.
676 virtual void gc_prologue(bool full);
677 virtual void gc_epilogue(bool full);
678
679 // We register a region with the fast "in collection set" test. We
680 // simply set to true the array slot corresponding to this region.
681 void register_region_with_in_cset_fast_test(HeapRegion* r) {
682 assert(_in_cset_fast_test_base != NULL, "sanity");
683 assert(r->in_collection_set(), "invariant");
684 uint index = r->hrs_index();
685 assert(index < _in_cset_fast_test_length, "invariant");
686 assert(!_in_cset_fast_test_base[index], "invariant");
687 _in_cset_fast_test_base[index] = true;
688 }
689
690 // This is a fast test on whether a reference points into the
691 // collection set or not. It does not assume that the reference
692 // points into the heap; if it doesn't, it will return false.
693 bool in_cset_fast_test(oop obj) {
694 assert(_in_cset_fast_test != NULL, "sanity");
695 if (_g1_committed.contains((HeapWord*) obj)) {
696 // no need to subtract the bottom of the heap from obj,
697 // _in_cset_fast_test is biased
698 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
699 bool ret = _in_cset_fast_test[index];
700 // let's make sure the result is consistent with what the slower
701 // test returns
702 assert( ret || !obj_in_cs(obj), "sanity");
703 assert(!ret || obj_in_cs(obj), "sanity");
704 return ret;
705 } else {
706 return false;
707 }
708 }
709
710 void clear_cset_fast_test() {
711 assert(_in_cset_fast_test_base != NULL, "sanity");
712 memset(_in_cset_fast_test_base, false,
713 (size_t) _in_cset_fast_test_length * sizeof(bool));
714 }
715
716 // This is called at the start of either a concurrent cycle or a Full
717 // GC to update the number of old marking cycles started.
718 void increment_old_marking_cycles_started();
719
720 // This is called at the end of either a concurrent cycle or a Full
721 // GC to update the number of old marking cycles completed. Those two
722 // can happen in a nested fashion, i.e., we start a concurrent
723 // cycle, a Full GC happens half-way through it which ends first,
724 // and then the cycle notices that a Full GC happened and ends
725 // too. The concurrent parameter is a boolean to help us do a bit
726 // tighter consistency checking in the method. If concurrent is
727 // false, the caller is the inner caller in the nesting (i.e., the
728 // Full GC). If concurrent is true, the caller is the outer caller
729 // in this nesting (i.e., the concurrent cycle). Further nesting is
730 // not currently supported. The end of this call also notifies
731 // the FullGCCount_lock in case a Java thread is waiting for a full
732 // GC to happen (e.g., it called System.gc() with
733 // +ExplicitGCInvokesConcurrent).
734 void increment_old_marking_cycles_completed(bool concurrent);
735
736 unsigned int old_marking_cycles_completed() {
737 return _old_marking_cycles_completed;
738 }
739
740 G1HRPrinter* hr_printer() { return &_hr_printer; }
741
742 protected:
743
744 // Shrink the garbage-first heap by at most the given size (in bytes!).
745 // (Rounds down to a HeapRegion boundary.)
746 virtual void shrink(size_t expand_bytes);
747 void shrink_helper(size_t expand_bytes);
748
749 #if TASKQUEUE_STATS
750 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
751 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
752 void reset_taskqueue_stats();
753 #endif // TASKQUEUE_STATS
754
755 // Schedule the VM operation that will do an evacuation pause to
756 // satisfy an allocation request of word_size. *succeeded will
757 // return whether the VM operation was successful (it did do an
758 // evacuation pause) or not (another thread beat us to it or the GC
759 // locker was active). Given that we should not be holding the
760 // Heap_lock when we enter this method, we will pass the
761 // gc_count_before (i.e., total_collections()) as a parameter since
762 // it has to be read while holding the Heap_lock. Currently, both
763 // methods that call do_collection_pause() release the Heap_lock
764 // before the call, so it's easy to read gc_count_before just before.
765 HeapWord* do_collection_pause(size_t word_size,
766 unsigned int gc_count_before,
767 bool* succeeded);
768
769 // The guts of the incremental collection pause, executed by the vm
770 // thread. It returns false if it is unable to do the collection due
771 // to the GC locker being active, true otherwise
772 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
773
774 // Actually do the work of evacuating the collection set.
775 void evacuate_collection_set();
776
777 // The g1 remembered set of the heap.
778 G1RemSet* _g1_rem_set;
779 // And it's mod ref barrier set, used to track updates for the above.
780 ModRefBarrierSet* _mr_bs;
781
782 // A set of cards that cover the objects for which the Rsets should be updated
783 // concurrently after the collection.
784 DirtyCardQueueSet _dirty_card_queue_set;
785
786 // The Heap Region Rem Set Iterator.
787 HeapRegionRemSetIterator** _rem_set_iterator;
788
789 // The closure used to refine a single card.
790 RefineCardTableEntryClosure* _refine_cte_cl;
791
792 // A function to check the consistency of dirty card logs.
793 void check_ct_logs_at_safepoint();
794
795 // A DirtyCardQueueSet that is used to hold cards that contain
796 // references into the current collection set. This is used to
797 // update the remembered sets of the regions in the collection
798 // set in the event of an evacuation failure.
799 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
800
801 // After a collection pause, make the regions in the CS into free
802 // regions.
803 void free_collection_set(HeapRegion* cs_head);
804
805 // Abandon the current collection set without recording policy
806 // statistics or updating free lists.
807 void abandon_collection_set(HeapRegion* cs_head);
808
809 // Applies "scan_non_heap_roots" to roots outside the heap,
810 // "scan_rs" to roots inside the heap (having done "set_region" to
811 // indicate the region in which the root resides),
812 // and does "scan_metadata" If "scan_rs" is
813 // NULL, then this step is skipped. The "worker_i"
814 // param is for use with parallel roots processing, and should be
815 // the "i" of the calling parallel worker thread's work(i) function.
816 // In the sequential case this param will be ignored.
817 void g1_process_strong_roots(bool is_scavenging,
818 ScanningOption so,
819 OopClosure* scan_non_heap_roots,
820 OopsInHeapRegionClosure* scan_rs,
821 G1KlassScanClosure* scan_klasses,
822 int worker_i);
823
824 // Apply "blk" to all the weak roots of the system. These include
825 // JNI weak roots, the code cache, system dictionary, symbol table,
826 // string table, and referents of reachable weak refs.
827 void g1_process_weak_roots(OopClosure* root_closure,
828 OopClosure* non_root_closure);
829
830 // Frees a non-humongous region by initializing its contents and
831 // adding it to the free list that's passed as a parameter (this is
832 // usually a local list which will be appended to the master free
833 // list later). The used bytes of freed regions are accumulated in
834 // pre_used. If par is true, the region's RSet will not be freed
835 // up. The assumption is that this will be done later.
836 void free_region(HeapRegion* hr,
837 size_t* pre_used,
838 FreeRegionList* free_list,
839 bool par);
840
841 // Frees a humongous region by collapsing it into individual regions
842 // and calling free_region() for each of them. The freed regions
843 // will be added to the free list that's passed as a parameter (this
844 // is usually a local list which will be appended to the master free
845 // list later). The used bytes of freed regions are accumulated in
846 // pre_used. If par is true, the region's RSet will not be freed
847 // up. The assumption is that this will be done later.
848 void free_humongous_region(HeapRegion* hr,
849 size_t* pre_used,
850 FreeRegionList* free_list,
851 HumongousRegionSet* humongous_proxy_set,
852 bool par);
853
854 // Notifies all the necessary spaces that the committed space has
855 // been updated (either expanded or shrunk). It should be called
856 // after _g1_storage is updated.
857 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
858
859 // The concurrent marker (and the thread it runs in.)
860 ConcurrentMark* _cm;
861 ConcurrentMarkThread* _cmThread;
862 bool _mark_in_progress;
863
864 // The concurrent refiner.
865 ConcurrentG1Refine* _cg1r;
866
867 // The parallel task queues
868 RefToScanQueueSet *_task_queues;
869
870 // True iff a evacuation has failed in the current collection.
871 bool _evacuation_failed;
872
873 // Set the attribute indicating whether evacuation has failed in the
874 // current collection.
875 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
876
877 // Failed evacuations cause some logical from-space objects to have
878 // forwarding pointers to themselves. Reset them.
879 void remove_self_forwarding_pointers();
880
881 // When one is non-null, so is the other. Together, they each pair is
882 // an object with a preserved mark, and its mark value.
883 Stack<oop, mtGC> _objs_with_preserved_marks;
884 Stack<markOop, mtGC> _preserved_marks_of_objs;
885
886 // Preserve the mark of "obj", if necessary, in preparation for its mark
887 // word being overwritten with a self-forwarding-pointer.
888 void preserve_mark_if_necessary(oop obj, markOop m);
889
890 // The stack of evac-failure objects left to be scanned.
891 GrowableArray<oop>* _evac_failure_scan_stack;
892 // The closure to apply to evac-failure objects.
893
894 OopsInHeapRegionClosure* _evac_failure_closure;
895 // Set the field above.
896 void
897 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
898 _evac_failure_closure = evac_failure_closure;
899 }
900
901 // Push "obj" on the scan stack.
902 void push_on_evac_failure_scan_stack(oop obj);
903 // Process scan stack entries until the stack is empty.
904 void drain_evac_failure_scan_stack();
905 // True iff an invocation of "drain_scan_stack" is in progress; to
906 // prevent unnecessary recursion.
907 bool _drain_in_progress;
908
909 // Do any necessary initialization for evacuation-failure handling.
910 // "cl" is the closure that will be used to process evac-failure
911 // objects.
912 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
913 // Do any necessary cleanup for evacuation-failure handling data
914 // structures.
915 void finalize_for_evac_failure();
916
917 // An attempt to evacuate "obj" has failed; take necessary steps.
918 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
919 void handle_evacuation_failure_common(oop obj, markOop m);
920
921 #ifndef PRODUCT
922 // Support for forcing evacuation failures. Analogous to
923 // PromotionFailureALot for the other collectors.
924
925 // Records whether G1EvacuationFailureALot should be in effect
926 // for the current GC
927 bool _evacuation_failure_alot_for_current_gc;
928
929 // Used to record the GC number for interval checking when
930 // determining whether G1EvaucationFailureALot is in effect
931 // for the current GC.
932 size_t _evacuation_failure_alot_gc_number;
933
934 // Count of the number of evacuations between failures.
935 volatile size_t _evacuation_failure_alot_count;
936
937 // Set whether G1EvacuationFailureALot should be in effect
938 // for the current GC (based upon the type of GC and which
939 // command line flags are set);
940 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
941 bool during_initial_mark,
942 bool during_marking);
943
944 inline void set_evacuation_failure_alot_for_current_gc();
945
946 // Return true if it's time to cause an evacuation failure.
947 inline bool evacuation_should_fail();
948
949 // Reset the G1EvacuationFailureALot counters. Should be called at
950 // the end of an evacuation pause in which an evacuation failure ocurred.
951 inline void reset_evacuation_should_fail();
952 #endif // !PRODUCT
953
954 // ("Weak") Reference processing support.
955 //
956 // G1 has 2 instances of the referece processor class. One
957 // (_ref_processor_cm) handles reference object discovery
958 // and subsequent processing during concurrent marking cycles.
959 //
960 // The other (_ref_processor_stw) handles reference object
961 // discovery and processing during full GCs and incremental
962 // evacuation pauses.
963 //
964 // During an incremental pause, reference discovery will be
965 // temporarily disabled for _ref_processor_cm and will be
966 // enabled for _ref_processor_stw. At the end of the evacuation
967 // pause references discovered by _ref_processor_stw will be
968 // processed and discovery will be disabled. The previous
969 // setting for reference object discovery for _ref_processor_cm
970 // will be re-instated.
971 //
972 // At the start of marking:
973 // * Discovery by the CM ref processor is verified to be inactive
974 // and it's discovered lists are empty.
975 // * Discovery by the CM ref processor is then enabled.
976 //
977 // At the end of marking:
978 // * Any references on the CM ref processor's discovered
979 // lists are processed (possibly MT).
980 //
981 // At the start of full GC we:
982 // * Disable discovery by the CM ref processor and
983 // empty CM ref processor's discovered lists
984 // (without processing any entries).
985 // * Verify that the STW ref processor is inactive and it's
986 // discovered lists are empty.
987 // * Temporarily set STW ref processor discovery as single threaded.
988 // * Temporarily clear the STW ref processor's _is_alive_non_header
989 // field.
990 // * Finally enable discovery by the STW ref processor.
991 //
992 // The STW ref processor is used to record any discovered
993 // references during the full GC.
994 //
995 // At the end of a full GC we:
996 // * Enqueue any reference objects discovered by the STW ref processor
997 // that have non-live referents. This has the side-effect of
998 // making the STW ref processor inactive by disabling discovery.
999 // * Verify that the CM ref processor is still inactive
1000 // and no references have been placed on it's discovered
1001 // lists (also checked as a precondition during initial marking).
1002
1003 // The (stw) reference processor...
1004 ReferenceProcessor* _ref_processor_stw;
1005
1006 // During reference object discovery, the _is_alive_non_header
1007 // closure (if non-null) is applied to the referent object to
1008 // determine whether the referent is live. If so then the
1009 // reference object does not need to be 'discovered' and can
1010 // be treated as a regular oop. This has the benefit of reducing
1011 // the number of 'discovered' reference objects that need to
1012 // be processed.
1013 //
1014 // Instance of the is_alive closure for embedding into the
1015 // STW reference processor as the _is_alive_non_header field.
1016 // Supplying a value for the _is_alive_non_header field is
1017 // optional but doing so prevents unnecessary additions to
1018 // the discovered lists during reference discovery.
1019 G1STWIsAliveClosure _is_alive_closure_stw;
1020
1021 // The (concurrent marking) reference processor...
1022 ReferenceProcessor* _ref_processor_cm;
1023
1024 // Instance of the concurrent mark is_alive closure for embedding
1025 // into the Concurrent Marking reference processor as the
1026 // _is_alive_non_header field. Supplying a value for the
1027 // _is_alive_non_header field is optional but doing so prevents
1028 // unnecessary additions to the discovered lists during reference
1029 // discovery.
1030 G1CMIsAliveClosure _is_alive_closure_cm;
1031
1032 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1033 HeapRegion** _worker_cset_start_region;
1034
1035 // Time stamp to validate the regions recorded in the cache
1036 // used by G1CollectedHeap::start_cset_region_for_worker().
1037 // The heap region entry for a given worker is valid iff
1038 // the associated time stamp value matches the current value
1039 // of G1CollectedHeap::_gc_time_stamp.
1040 unsigned int* _worker_cset_start_region_time_stamp;
1041
1042 enum G1H_process_strong_roots_tasks {
1043 G1H_PS_filter_satb_buffers,
1044 G1H_PS_refProcessor_oops_do,
1045 // Leave this one last.
1046 G1H_PS_NumElements
1047 };
1048
1049 SubTasksDone* _process_strong_tasks;
1050
1051 volatile bool _free_regions_coming;
1052
1053 public:
1054
1055 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1056
1057 void set_refine_cte_cl_concurrency(bool concurrent);
1058
1059 RefToScanQueue *task_queue(int i) const;
1060
1061 // A set of cards where updates happened during the GC
1062 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1063
1064 // A DirtyCardQueueSet that is used to hold cards that contain
1065 // references into the current collection set. This is used to
1066 // update the remembered sets of the regions in the collection
1067 // set in the event of an evacuation failure.
1068 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1069 { return _into_cset_dirty_card_queue_set; }
1070
1071 // Create a G1CollectedHeap with the specified policy.
1072 // Must call the initialize method afterwards.
1073 // May not return if something goes wrong.
1074 G1CollectedHeap(G1CollectorPolicy* policy);
1075
1076 // Initialize the G1CollectedHeap to have the initial and
1077 // maximum sizes and remembered and barrier sets
1078 // specified by the policy object.
1079 jint initialize();
1080
1081 // Initialize weak reference processing.
1082 virtual void ref_processing_init();
1083
1084 void set_par_threads(uint t) {
1085 SharedHeap::set_par_threads(t);
1086 // Done in SharedHeap but oddly there are
1087 // two _process_strong_tasks's in a G1CollectedHeap
1088 // so do it here too.
1089 _process_strong_tasks->set_n_threads(t);
1090 }
1091
1092 // Set _n_par_threads according to a policy TBD.
1093 void set_par_threads();
1094
1095 void set_n_termination(int t) {
1096 _process_strong_tasks->set_n_threads(t);
1097 }
1098
1099 virtual CollectedHeap::Name kind() const {
1100 return CollectedHeap::G1CollectedHeap;
1101 }
1102
1103 // The current policy object for the collector.
1104 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1105
1106 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1107
1108 // Adaptive size policy. No such thing for g1.
1109 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1110
1111 // The rem set and barrier set.
1112 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1113 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1114
1115 // The rem set iterator.
1116 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1117 return _rem_set_iterator[i];
1118 }
1119
1120 HeapRegionRemSetIterator* rem_set_iterator() {
1121 return _rem_set_iterator[0];
1122 }
1123
1124 unsigned get_gc_time_stamp() {
1125 return _gc_time_stamp;
1126 }
1127
1128 void reset_gc_time_stamp() {
1129 _gc_time_stamp = 0;
1130 OrderAccess::fence();
1131 // Clear the cached CSet starting regions and time stamps.
1132 // Their validity is dependent on the GC timestamp.
1133 clear_cset_start_regions();
1134 }
1135
1136 void check_gc_time_stamps() PRODUCT_RETURN;
1137
1138 void increment_gc_time_stamp() {
1139 ++_gc_time_stamp;
1140 OrderAccess::fence();
1141 }
1142
1143 // Reset the given region's GC timestamp. If it's starts humongous,
1144 // also reset the GC timestamp of its corresponding
1145 // continues humongous regions too.
1146 void reset_gc_time_stamps(HeapRegion* hr);
1147
1148 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1149 DirtyCardQueue* into_cset_dcq,
1150 bool concurrent, int worker_i);
1151
1152 // The shared block offset table array.
1153 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1154
1155 // Reference Processing accessors
1156
1157 // The STW reference processor....
1158 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1159
1160 // The Concurent Marking reference processor...
1161 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1162
1163 virtual size_t capacity() const;
1164 virtual size_t used() const;
1165 // This should be called when we're not holding the heap lock. The
1166 // result might be a bit inaccurate.
1167 size_t used_unlocked() const;
1168 size_t recalculate_used() const;
1169
1170 // These virtual functions do the actual allocation.
1171 // Some heaps may offer a contiguous region for shared non-blocking
1172 // allocation, via inlined code (by exporting the address of the top and
1173 // end fields defining the extent of the contiguous allocation region.)
1174 // But G1CollectedHeap doesn't yet support this.
1175
1176 // Return an estimate of the maximum allocation that could be performed
1177 // without triggering any collection or expansion activity. In a
1178 // generational collector, for example, this is probably the largest
1179 // allocation that could be supported (without expansion) in the youngest
1180 // generation. It is "unsafe" because no locks are taken; the result
1181 // should be treated as an approximation, not a guarantee, for use in
1182 // heuristic resizing decisions.
1183 virtual size_t unsafe_max_alloc();
1184
1185 virtual bool is_maximal_no_gc() const {
1186 return _g1_storage.uncommitted_size() == 0;
1187 }
1188
1189 // The total number of regions in the heap.
1190 uint n_regions() { return _hrs.length(); }
1191
1192 // The max number of regions in the heap.
1193 uint max_regions() { return _hrs.max_length(); }
1194
1195 // The number of regions that are completely free.
1196 uint free_regions() { return _free_list.length(); }
1197
1198 // The number of regions that are not completely free.
1199 uint used_regions() { return n_regions() - free_regions(); }
1200
1201 // The number of regions available for "regular" expansion.
1202 uint expansion_regions() { return _expansion_regions; }
1203
1204 // Factory method for HeapRegion instances. It will return NULL if
1205 // the allocation fails.
1206 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1207
1208 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1209 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1210 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1211 void verify_dirty_young_regions() PRODUCT_RETURN;
1212
1213 // verify_region_sets() performs verification over the region
1214 // lists. It will be compiled in the product code to be used when
1215 // necessary (i.e., during heap verification).
1216 void verify_region_sets();
1217
1218 // verify_region_sets_optional() is planted in the code for
1219 // list verification in non-product builds (and it can be enabled in
1220 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1221 #if HEAP_REGION_SET_FORCE_VERIFY
1222 void verify_region_sets_optional() {
1223 verify_region_sets();
1224 }
1225 #else // HEAP_REGION_SET_FORCE_VERIFY
1226 void verify_region_sets_optional() { }
1227 #endif // HEAP_REGION_SET_FORCE_VERIFY
1228
1229 #ifdef ASSERT
1230 bool is_on_master_free_list(HeapRegion* hr) {
1231 return hr->containing_set() == &_free_list;
1232 }
1233
1234 bool is_in_humongous_set(HeapRegion* hr) {
1235 return hr->containing_set() == &_humongous_set;
1236 }
1237 #endif // ASSERT
1238
1239 // Wrapper for the region list operations that can be called from
1240 // methods outside this class.
1241
1242 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1243 _secondary_free_list.add_as_tail(list);
1244 }
1245
1246 void append_secondary_free_list() {
1247 _free_list.add_as_head(&_secondary_free_list);
1248 }
1249
1250 void append_secondary_free_list_if_not_empty_with_lock() {
1251 // If the secondary free list looks empty there's no reason to
1252 // take the lock and then try to append it.
1253 if (!_secondary_free_list.is_empty()) {
1254 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1255 append_secondary_free_list();
1256 }
1257 }
1258
1259 void old_set_remove(HeapRegion* hr) {
1260 _old_set.remove(hr);
1261 }
1262
1263 size_t non_young_capacity_bytes() {
1264 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1265 }
1266
1267 void set_free_regions_coming();
1268 void reset_free_regions_coming();
1269 bool free_regions_coming() { return _free_regions_coming; }
1270 void wait_while_free_regions_coming();
1271
1272 // Determine whether the given region is one that we are using as an
1273 // old GC alloc region.
1274 bool is_old_gc_alloc_region(HeapRegion* hr) {
1275 return hr == _retained_old_gc_alloc_region;
1276 }
1277
1278 // Perform a collection of the heap; intended for use in implementing
1279 // "System.gc". This probably implies as full a collection as the
1280 // "CollectedHeap" supports.
1281 virtual void collect(GCCause::Cause cause);
1282
1283 // The same as above but assume that the caller holds the Heap_lock.
1284 void collect_locked(GCCause::Cause cause);
1285
1286 // True iff a evacuation has failed in the most-recent collection.
1287 bool evacuation_failed() { return _evacuation_failed; }
1288
1289 // It will free a region if it has allocated objects in it that are
1290 // all dead. It calls either free_region() or
1291 // free_humongous_region() depending on the type of the region that
1292 // is passed to it.
1293 void free_region_if_empty(HeapRegion* hr,
1294 size_t* pre_used,
1295 FreeRegionList* free_list,
1296 OldRegionSet* old_proxy_set,
1297 HumongousRegionSet* humongous_proxy_set,
1298 HRRSCleanupTask* hrrs_cleanup_task,
1299 bool par);
1300
1301 // It appends the free list to the master free list and updates the
1302 // master humongous list according to the contents of the proxy
1303 // list. It also adjusts the total used bytes according to pre_used
1304 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1305 void update_sets_after_freeing_regions(size_t pre_used,
1306 FreeRegionList* free_list,
1307 OldRegionSet* old_proxy_set,
1308 HumongousRegionSet* humongous_proxy_set,
1309 bool par);
1310
1311 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1312 virtual bool is_in(const void* p) const;
1313
1314 // Return "TRUE" iff the given object address is within the collection
1315 // set.
1316 inline bool obj_in_cs(oop obj);
1317
1318 // Return "TRUE" iff the given object address is in the reserved
1319 // region of g1.
1320 bool is_in_g1_reserved(const void* p) const {
1321 return _g1_reserved.contains(p);
1322 }
1323
1324 // Returns a MemRegion that corresponds to the space that has been
1325 // reserved for the heap
1326 MemRegion g1_reserved() {
1327 return _g1_reserved;
1328 }
1329
1330 // Returns a MemRegion that corresponds to the space that has been
1331 // committed in the heap
1332 MemRegion g1_committed() {
1333 return _g1_committed;
1334 }
1335
1336 virtual bool is_in_closed_subset(const void* p) const;
1337
1338 // This resets the card table to all zeros. It is used after
1339 // a collection pause which used the card table to claim cards.
1340 void cleanUpCardTable();
1341
1342 // Iteration functions.
1343
1344 // Iterate over all the ref-containing fields of all objects, calling
1345 // "cl.do_oop" on each.
1346 virtual void oop_iterate(ExtendedOopClosure* cl);
1347
1348 // Same as above, restricted to a memory region.
1349 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1350
1351 // Iterate over all objects, calling "cl.do_object" on each.
1352 virtual void object_iterate(ObjectClosure* cl);
1353
1354 virtual void safe_object_iterate(ObjectClosure* cl) {
1355 object_iterate(cl);
1356 }
1357
1358 // Iterate over all objects allocated since the last collection, calling
1359 // "cl.do_object" on each. The heap must have been initialized properly
1360 // to support this function, or else this call will fail.
1361 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1362
1363 // Iterate over all spaces in use in the heap, in ascending address order.
1364 virtual void space_iterate(SpaceClosure* cl);
1365
1366 // Iterate over heap regions, in address order, terminating the
1367 // iteration early if the "doHeapRegion" method returns "true".
1368 void heap_region_iterate(HeapRegionClosure* blk) const;
1369
1370 // Return the region with the given index. It assumes the index is valid.
1371 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1372
1373 // Divide the heap region sequence into "chunks" of some size (the number
1374 // of regions divided by the number of parallel threads times some
1375 // overpartition factor, currently 4). Assumes that this will be called
1376 // in parallel by ParallelGCThreads worker threads with discinct worker
1377 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1378 // calls will use the same "claim_value", and that that claim value is
1379 // different from the claim_value of any heap region before the start of
1380 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1381 // attempting to claim the first region in each chunk, and, if
1382 // successful, applying the closure to each region in the chunk (and
1383 // setting the claim value of the second and subsequent regions of the
1384 // chunk.) For now requires that "doHeapRegion" always returns "false",
1385 // i.e., that a closure never attempt to abort a traversal.
1386 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1387 uint worker,
1388 uint no_of_par_workers,
1389 jint claim_value);
1390
1391 // It resets all the region claim values to the default.
1392 void reset_heap_region_claim_values();
1393
1394 // Resets the claim values of regions in the current
1395 // collection set to the default.
1396 void reset_cset_heap_region_claim_values();
1397
1398 #ifdef ASSERT
1399 bool check_heap_region_claim_values(jint claim_value);
1400
1401 // Same as the routine above but only checks regions in the
1402 // current collection set.
1403 bool check_cset_heap_region_claim_values(jint claim_value);
1404 #endif // ASSERT
1405
1406 // Clear the cached cset start regions and (more importantly)
1407 // the time stamps. Called when we reset the GC time stamp.
1408 void clear_cset_start_regions();
1409
1410 // Given the id of a worker, obtain or calculate a suitable
1411 // starting region for iterating over the current collection set.
1412 HeapRegion* start_cset_region_for_worker(int worker_i);
1413
1414 // This is a convenience method that is used by the
1415 // HeapRegionIterator classes to calculate the starting region for
1416 // each worker so that they do not all start from the same region.
1417 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1418
1419 // Iterate over the regions (if any) in the current collection set.
1420 void collection_set_iterate(HeapRegionClosure* blk);
1421
1422 // As above but starting from region r
1423 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1424
1425 // Returns the first (lowest address) compactible space in the heap.
1426 virtual CompactibleSpace* first_compactible_space();
1427
1428 // A CollectedHeap will contain some number of spaces. This finds the
1429 // space containing a given address, or else returns NULL.
1430 virtual Space* space_containing(const void* addr) const;
1431
1432 // A G1CollectedHeap will contain some number of heap regions. This
1433 // finds the region containing a given address, or else returns NULL.
1434 template <class T>
1435 inline HeapRegion* heap_region_containing(const T addr) const;
1436
1437 // Like the above, but requires "addr" to be in the heap (to avoid a
1438 // null-check), and unlike the above, may return an continuing humongous
1439 // region.
1440 template <class T>
1441 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1442
1443 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1444 // each address in the (reserved) heap is a member of exactly
1445 // one block. The defining characteristic of a block is that it is
1446 // possible to find its size, and thus to progress forward to the next
1447 // block. (Blocks may be of different sizes.) Thus, blocks may
1448 // represent Java objects, or they might be free blocks in a
1449 // free-list-based heap (or subheap), as long as the two kinds are
1450 // distinguishable and the size of each is determinable.
1451
1452 // Returns the address of the start of the "block" that contains the
1453 // address "addr". We say "blocks" instead of "object" since some heaps
1454 // may not pack objects densely; a chunk may either be an object or a
1455 // non-object.
1456 virtual HeapWord* block_start(const void* addr) const;
1457
1458 // Requires "addr" to be the start of a chunk, and returns its size.
1459 // "addr + size" is required to be the start of a new chunk, or the end
1460 // of the active area of the heap.
1461 virtual size_t block_size(const HeapWord* addr) const;
1462
1463 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1464 // the block is an object.
1465 virtual bool block_is_obj(const HeapWord* addr) const;
1466
1467 // Does this heap support heap inspection? (+PrintClassHistogram)
1468 virtual bool supports_heap_inspection() const { return true; }
1469
1470 // Section on thread-local allocation buffers (TLABs)
1471 // See CollectedHeap for semantics.
1472
1473 virtual bool supports_tlab_allocation() const;
1474 virtual size_t tlab_capacity(Thread* thr) const;
1475 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1476
1477 // Can a compiler initialize a new object without store barriers?
1478 // This permission only extends from the creation of a new object
1479 // via a TLAB up to the first subsequent safepoint. If such permission
1480 // is granted for this heap type, the compiler promises to call
1481 // defer_store_barrier() below on any slow path allocation of
1482 // a new object for which such initializing store barriers will
1483 // have been elided. G1, like CMS, allows this, but should be
1484 // ready to provide a compensating write barrier as necessary
1485 // if that storage came out of a non-young region. The efficiency
1486 // of this implementation depends crucially on being able to
1487 // answer very efficiently in constant time whether a piece of
1488 // storage in the heap comes from a young region or not.
1489 // See ReduceInitialCardMarks.
1490 virtual bool can_elide_tlab_store_barriers() const {
1491 return true;
1492 }
1493
1494 virtual bool card_mark_must_follow_store() const {
1495 return true;
1496 }
1497
1498 bool is_in_young(const oop obj) {
1499 HeapRegion* hr = heap_region_containing(obj);
1500 return hr != NULL && hr->is_young();
1501 }
1502
1503 #ifdef ASSERT
1504 virtual bool is_in_partial_collection(const void* p);
1505 #endif
1506
1507 virtual bool is_scavengable(const void* addr);
1508
1509 // We don't need barriers for initializing stores to objects
1510 // in the young gen: for the SATB pre-barrier, there is no
1511 // pre-value that needs to be remembered; for the remembered-set
1512 // update logging post-barrier, we don't maintain remembered set
1513 // information for young gen objects.
1514 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1515 return is_in_young(new_obj);
1516 }
1517
1518 // Returns "true" iff the given word_size is "very large".
1519 static bool isHumongous(size_t word_size) {
1520 // Note this has to be strictly greater-than as the TLABs
1521 // are capped at the humongous thresold and we want to
1522 // ensure that we don't try to allocate a TLAB as
1523 // humongous and that we don't allocate a humongous
1524 // object in a TLAB.
1525 return word_size > _humongous_object_threshold_in_words;
1526 }
1527
1528 // Update mod union table with the set of dirty cards.
1529 void updateModUnion();
1530
1531 // Set the mod union bits corresponding to the given memRegion. Note
1532 // that this is always a safe operation, since it doesn't clear any
1533 // bits.
1534 void markModUnionRange(MemRegion mr);
1535
1536 // Records the fact that a marking phase is no longer in progress.
1537 void set_marking_complete() {
1538 _mark_in_progress = false;
1539 }
1540 void set_marking_started() {
1541 _mark_in_progress = true;
1542 }
1543 bool mark_in_progress() {
1544 return _mark_in_progress;
1545 }
1546
1547 // Print the maximum heap capacity.
1548 virtual size_t max_capacity() const;
1549
1550 virtual jlong millis_since_last_gc();
1551
1552 // Perform any cleanup actions necessary before allowing a verification.
1553 virtual void prepare_for_verify();
1554
1555 // Perform verification.
1556
1557 // vo == UsePrevMarking -> use "prev" marking information,
1558 // vo == UseNextMarking -> use "next" marking information
1559 // vo == UseMarkWord -> use the mark word in the object header
1560 //
1561 // NOTE: Only the "prev" marking information is guaranteed to be
1562 // consistent most of the time, so most calls to this should use
1563 // vo == UsePrevMarking.
1564 // Currently, there is only one case where this is called with
1565 // vo == UseNextMarking, which is to verify the "next" marking
1566 // information at the end of remark.
1567 // Currently there is only one place where this is called with
1568 // vo == UseMarkWord, which is to verify the marking during a
1569 // full GC.
1570 void verify(bool silent, VerifyOption vo);
1571
1572 // Override; it uses the "prev" marking information
1573 virtual void verify(bool silent);
1574 virtual void print_on(outputStream* st) const;
1575 virtual void print_extended_on(outputStream* st) const;
1576
1577 virtual void print_gc_threads_on(outputStream* st) const;
1578 virtual void gc_threads_do(ThreadClosure* tc) const;
1579
1580 // Override
1581 void print_tracing_info() const;
1582
1583 // The following two methods are helpful for debugging RSet issues.
1584 void print_cset_rsets() PRODUCT_RETURN;
1585 void print_all_rsets() PRODUCT_RETURN;
1586
1587 // Convenience function to be used in situations where the heap type can be
1588 // asserted to be this type.
1589 static G1CollectedHeap* heap();
1590
1591 void set_region_short_lived_locked(HeapRegion* hr);
1592 // add appropriate methods for any other surv rate groups
1593
1594 YoungList* young_list() { return _young_list; }
1595
1596 // debugging
1597 bool check_young_list_well_formed() {
1598 return _young_list->check_list_well_formed();
1599 }
1600
1601 bool check_young_list_empty(bool check_heap,
1602 bool check_sample = true);
1603
1604 // *** Stuff related to concurrent marking. It's not clear to me that so
1605 // many of these need to be public.
1606
1607 // The functions below are helper functions that a subclass of
1608 // "CollectedHeap" can use in the implementation of its virtual
1609 // functions.
1610 // This performs a concurrent marking of the live objects in a
1611 // bitmap off to the side.
1612 void doConcurrentMark();
1613
1614 bool isMarkedPrev(oop obj) const;
1615 bool isMarkedNext(oop obj) const;
1616
1617 // Determine if an object is dead, given the object and also
1618 // the region to which the object belongs. An object is dead
1619 // iff a) it was not allocated since the last mark and b) it
1620 // is not marked.
1621
1622 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1623 return
1624 !hr->obj_allocated_since_prev_marking(obj) &&
1625 !isMarkedPrev(obj);
1626 }
1627
1628 // This function returns true when an object has been
1629 // around since the previous marking and hasn't yet
1630 // been marked during this marking.
1631
1632 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1633 return
1634 !hr->obj_allocated_since_next_marking(obj) &&
1635 !isMarkedNext(obj);
1636 }
1637
1638 // Determine if an object is dead, given only the object itself.
1639 // This will find the region to which the object belongs and
1640 // then call the region version of the same function.
1641
1642 // Added if it is NULL it isn't dead.
1643
1644 bool is_obj_dead(const oop obj) const {
1645 const HeapRegion* hr = heap_region_containing(obj);
1646 if (hr == NULL) {
1647 if (obj == NULL) return false;
1648 else return true;
1649 }
1650 else return is_obj_dead(obj, hr);
1651 }
1652
1653 bool is_obj_ill(const oop obj) const {
1654 const HeapRegion* hr = heap_region_containing(obj);
1655 if (hr == NULL) {
1656 if (obj == NULL) return false;
1657 else return true;
1658 }
1659 else return is_obj_ill(obj, hr);
1660 }
1661
1662 // The methods below are here for convenience and dispatch the
1663 // appropriate method depending on value of the given VerifyOption
1664 // parameter. The options for that parameter are:
1665 //
1666 // vo == UsePrevMarking -> use "prev" marking information,
1667 // vo == UseNextMarking -> use "next" marking information,
1668 // vo == UseMarkWord -> use mark word from object header
1669
1670 bool is_obj_dead_cond(const oop obj,
1671 const HeapRegion* hr,
1672 const VerifyOption vo) const {
1673 switch (vo) {
1674 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1675 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1676 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1677 default: ShouldNotReachHere();
1678 }
1679 return false; // keep some compilers happy
1680 }
1681
1682 bool is_obj_dead_cond(const oop obj,
1683 const VerifyOption vo) const {
1684 switch (vo) {
1685 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1686 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1687 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1688 default: ShouldNotReachHere();
1689 }
1690 return false; // keep some compilers happy
1691 }
1692
1693 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1694 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1695 bool is_marked(oop obj, VerifyOption vo);
1696 const char* top_at_mark_start_str(VerifyOption vo);
1697
1698 // The following is just to alert the verification code
1699 // that a full collection has occurred and that the
1700 // remembered sets are no longer up to date.
1701 bool _full_collection;
1702 void set_full_collection() { _full_collection = true;}
1703 void clear_full_collection() {_full_collection = false;}
1704 bool full_collection() {return _full_collection;}
1705
1706 ConcurrentMark* concurrent_mark() const { return _cm; }
1707 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1708
1709 // The dirty cards region list is used to record a subset of regions
1710 // whose cards need clearing. The list if populated during the
1711 // remembered set scanning and drained during the card table
1712 // cleanup. Although the methods are reentrant, population/draining
1713 // phases must not overlap. For synchronization purposes the last
1714 // element on the list points to itself.
1715 HeapRegion* _dirty_cards_region_list;
1716 void push_dirty_cards_region(HeapRegion* hr);
1717 HeapRegion* pop_dirty_cards_region();
1718
1719 public:
1720 void stop_conc_gc_threads();
1721
1722 size_t pending_card_num();
1723 size_t cards_scanned();
1724
1725 protected:
1726 size_t _max_heap_capacity;
1727 };
1728
1729 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1730 private:
1731 bool _retired;
1732
1733 public:
1734 G1ParGCAllocBuffer(size_t gclab_word_size);
1735
1736 void set_buf(HeapWord* buf) {
1737 ParGCAllocBuffer::set_buf(buf);
1738 _retired = false;
1739 }
1740
1741 void retire(bool end_of_gc, bool retain) {
1742 if (_retired)
1743 return;
1744 ParGCAllocBuffer::retire(end_of_gc, retain);
1745 _retired = true;
1746 }
1747 };
1748
1749 class G1ParScanThreadState : public StackObj {
1750 protected:
1751 G1CollectedHeap* _g1h;
1752 RefToScanQueue* _refs;
1753 DirtyCardQueue _dcq;
1754 CardTableModRefBS* _ct_bs;
1755 G1RemSet* _g1_rem;
1756
1757 G1ParGCAllocBuffer _surviving_alloc_buffer;
1758 G1ParGCAllocBuffer _tenured_alloc_buffer;
1759 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1760 ageTable _age_table;
1761
1762 size_t _alloc_buffer_waste;
1763 size_t _undo_waste;
1764
1765 OopsInHeapRegionClosure* _evac_failure_cl;
1766 G1ParScanHeapEvacClosure* _evac_cl;
1767 G1ParScanPartialArrayClosure* _partial_scan_cl;
1768
1769 int _hash_seed;
1770 uint _queue_num;
1771
1772 size_t _term_attempts;
1773
1774 double _start;
1775 double _start_strong_roots;
1776 double _strong_roots_time;
1777 double _start_term;
1778 double _term_time;
1779
1780 // Map from young-age-index (0 == not young, 1 is youngest) to
1781 // surviving words. base is what we get back from the malloc call
1782 size_t* _surviving_young_words_base;
1783 // this points into the array, as we use the first few entries for padding
1784 size_t* _surviving_young_words;
1785
1786 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1787
1788 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1789
1790 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1791
1792 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1793 CardTableModRefBS* ctbs() { return _ct_bs; }
1794
1795 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1796 if (!from->is_survivor()) {
1797 _g1_rem->par_write_ref(from, p, tid);
1798 }
1799 }
1800
1801 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1802 // If the new value of the field points to the same region or
1803 // is the to-space, we don't need to include it in the Rset updates.
1804 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1805 size_t card_index = ctbs()->index_for(p);
1806 // If the card hasn't been added to the buffer, do it.
1807 if (ctbs()->mark_card_deferred(card_index)) {
1808 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1809 }
1810 }
1811 }
1812
1813 public:
1814 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1815
1816 ~G1ParScanThreadState() {
1817 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1818 }
1819
1820 RefToScanQueue* refs() { return _refs; }
1821 ageTable* age_table() { return &_age_table; }
1822
1823 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1824 return _alloc_buffers[purpose];
1825 }
1826
1827 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1828 size_t undo_waste() const { return _undo_waste; }
1829
1830 #ifdef ASSERT
1831 bool verify_ref(narrowOop* ref) const;
1832 bool verify_ref(oop* ref) const;
1833 bool verify_task(StarTask ref) const;
1834 #endif // ASSERT
1835
1836 template <class T> void push_on_queue(T* ref) {
1837 assert(verify_ref(ref), "sanity");
1838 refs()->push(ref);
1839 }
1840
1841 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1842 if (G1DeferredRSUpdate) {
1843 deferred_rs_update(from, p, tid);
1844 } else {
1845 immediate_rs_update(from, p, tid);
1846 }
1847 }
1848
1849 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1850 HeapWord* obj = NULL;
1851 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1852 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1853 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1854 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1855 alloc_buf->retire(false /* end_of_gc */, false /* retain */);
1856
1857 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1858 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1859 // Otherwise.
1860 alloc_buf->set_word_size(gclab_word_size);
1861 alloc_buf->set_buf(buf);
1862
1863 obj = alloc_buf->allocate(word_sz);
1864 assert(obj != NULL, "buffer was definitely big enough...");
1865 } else {
1866 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1867 }
1868 return obj;
1869 }
1870
1871 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1872 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1873 if (obj != NULL) return obj;
1874 return allocate_slow(purpose, word_sz);
1875 }
1876
1877 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1878 if (alloc_buffer(purpose)->contains(obj)) {
1879 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1880 "should contain whole object");
1881 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1882 } else {
1883 CollectedHeap::fill_with_object(obj, word_sz);
1884 add_to_undo_waste(word_sz);
1885 }
1886 }
1887
1888 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1889 _evac_failure_cl = evac_failure_cl;
1890 }
1891 OopsInHeapRegionClosure* evac_failure_closure() {
1892 return _evac_failure_cl;
1893 }
1894
1895 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1896 _evac_cl = evac_cl;
1897 }
1898
1899 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1900 _partial_scan_cl = partial_scan_cl;
1901 }
1902
1903 int* hash_seed() { return &_hash_seed; }
1904 uint queue_num() { return _queue_num; }
1905
1906 size_t term_attempts() const { return _term_attempts; }
1907 void note_term_attempt() { _term_attempts++; }
1908
1909 void start_strong_roots() {
1910 _start_strong_roots = os::elapsedTime();
1911 }
1912 void end_strong_roots() {
1913 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1914 }
1915 double strong_roots_time() const { return _strong_roots_time; }
1916
1917 void start_term_time() {
1918 note_term_attempt();
1919 _start_term = os::elapsedTime();
1920 }
1921 void end_term_time() {
1922 _term_time += (os::elapsedTime() - _start_term);
1923 }
1924 double term_time() const { return _term_time; }
1925
1926 double elapsed_time() const {
1927 return os::elapsedTime() - _start;
1928 }
1929
1930 static void
1931 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1932 void
1933 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1934
1935 size_t* surviving_young_words() {
1936 // We add on to hide entry 0 which accumulates surviving words for
1937 // age -1 regions (i.e. non-young ones)
1938 return _surviving_young_words;
1939 }
1940
1941 void retire_alloc_buffers() {
1942 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1943 size_t waste = _alloc_buffers[ap]->words_remaining();
1944 add_to_alloc_buffer_waste(waste);
1945 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1946 true /* end_of_gc */,
1947 false /* retain */);
1948 }
1949 }
1950
1951 template <class T> void deal_with_reference(T* ref_to_scan) {
1952 if (has_partial_array_mask(ref_to_scan)) {
1953 _partial_scan_cl->do_oop_nv(ref_to_scan);
1954 } else {
1955 // Note: we can use "raw" versions of "region_containing" because
1956 // "obj_to_scan" is definitely in the heap, and is not in a
1957 // humongous region.
1958 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1959 _evac_cl->set_region(r);
1960 _evac_cl->do_oop_nv(ref_to_scan);
1961 }
1962 }
1963
1964 void deal_with_reference(StarTask ref) {
1965 assert(verify_task(ref), "sanity");
1966 if (ref.is_narrow()) {
1967 deal_with_reference((narrowOop*)ref);
1968 } else {
1969 deal_with_reference((oop*)ref);
1970 }
1971 }
1972
1973 public:
1974 void trim_queue();
1975 };
1976
1977 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP