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.
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).
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23 */
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 bool do_object_b(oop p);
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 class RefineCardTableEntryClosure;
190
191 class G1CollectedHeap : public SharedHeap {
192 friend class VM_G1CollectForAllocation;
193 friend class VM_G1CollectFull;
194 friend class VM_G1IncCollectionPause;
195 friend class VMStructs;
196 friend class MutatorAllocRegion;
197 friend class SurvivorGCAllocRegion;
198 friend class OldGCAllocRegion;
199
200 // Closures used in implementation.
201 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
202 friend class G1ParCopyClosure;
203 friend class G1IsAliveClosure;
204 friend class G1EvacuateFollowersClosure;
205 friend class G1ParScanThreadState;
206 friend class G1ParScanClosureSuper;
207 friend class G1ParEvacuateFollowersClosure;
208 friend class G1ParTask;
209 friend class G1FreeGarbageRegionClosure;
210 friend class RefineCardTableEntryClosure;
211 friend class G1PrepareCompactClosure;
212 friend class RegionSorter;
213 friend class RegionResetter;
214 friend class CountRCClosure;
215 friend class EvacPopObjClosure;
216 friend class G1ParCleanupCTTask;
217
218 // Other related classes.
219 friend class G1MarkSweep;
220
221 private:
222 // The one and only G1CollectedHeap, so static functions can find it.
223 static G1CollectedHeap* _g1h;
224
225 static size_t _humongous_object_threshold_in_words;
226
227 // Storage for the G1 heap.
228 VirtualSpace _g1_storage;
229 MemRegion _g1_reserved;
230
231 // The part of _g1_storage that is currently committed.
232 MemRegion _g1_committed;
233
234 // The master free list. It will satisfy all new region allocations.
235 MasterFreeRegionList _free_list;
236
237 // The secondary free list which contains regions that have been
238 // freed up during the cleanup process. This will be appended to the
239 // master free list when appropriate.
240 SecondaryFreeRegionList _secondary_free_list;
241
242 // It keeps track of the old regions.
243 MasterOldRegionSet _old_set;
244
245 // It keeps track of the humongous regions.
246 MasterHumongousRegionSet _humongous_set;
247
248 // The number of regions we could create by expansion.
249 uint _expansion_regions;
250
251 // The block offset table for the G1 heap.
252 G1BlockOffsetSharedArray* _bot_shared;
253
254 // Tears down the region sets / lists so that they are empty and the
255 // regions on the heap do not belong to a region set / list. The
256 // only exception is the humongous set which we leave unaltered. If
257 // free_list_only is true, it will only tear down the master free
258 // list. It is called before a Full GC (free_list_only == false) or
259 // before heap shrinking (free_list_only == true).
260 void tear_down_region_sets(bool free_list_only);
261
262 // Rebuilds the region sets / lists so that they are repopulated to
263 // reflect the contents of the heap. The only exception is the
264 // humongous set which was not torn down in the first place. If
265 // free_list_only is true, it will only rebuild the master free
266 // list. It is called after a Full GC (free_list_only == false) or
267 // after heap shrinking (free_list_only == true).
268 void rebuild_region_sets(bool free_list_only);
269
270 // The sequence of all heap regions in the heap.
271 HeapRegionSeq _hrs;
272
273 // Alloc region used to satisfy mutator allocation requests.
274 MutatorAllocRegion _mutator_alloc_region;
275
276 // Alloc region used to satisfy allocation requests by the GC for
277 // survivor objects.
278 SurvivorGCAllocRegion _survivor_gc_alloc_region;
279
280 // PLAB sizing policy for survivors.
281 PLABStats _survivor_plab_stats;
282
283 // Alloc region used to satisfy allocation requests by the GC for
284 // old objects.
285 OldGCAllocRegion _old_gc_alloc_region;
286
287 // PLAB sizing policy for tenured objects.
288 PLABStats _old_plab_stats;
289
290 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
291 PLABStats* stats = NULL;
292
293 switch (purpose) {
294 case GCAllocForSurvived:
295 stats = &_survivor_plab_stats;
296 break;
297 case GCAllocForTenured:
298 stats = &_old_plab_stats;
299 break;
300 default:
301 assert(false, "unrecognized GCAllocPurpose");
302 }
303
304 return stats;
305 }
306
307 // The last old region we allocated to during the last GC.
308 // Typically, it is not full so we should re-use it during the next GC.
309 HeapRegion* _retained_old_gc_alloc_region;
310
311 // It specifies whether we should attempt to expand the heap after a
312 // region allocation failure. If heap expansion fails we set this to
313 // false so that we don't re-attempt the heap expansion (it's likely
314 // that subsequent expansion attempts will also fail if one fails).
315 // Currently, it is only consulted during GC and it's reset at the
316 // start of each GC.
317 bool _expand_heap_after_alloc_failure;
318
319 // It resets the mutator alloc region before new allocations can take place.
320 void init_mutator_alloc_region();
321
322 // It releases the mutator alloc region.
323 void release_mutator_alloc_region();
324
325 // It initializes the GC alloc regions at the start of a GC.
326 void init_gc_alloc_regions();
327
328 // It releases the GC alloc regions at the end of a GC.
329 void release_gc_alloc_regions(uint no_of_gc_workers);
330
331 // It does any cleanup that needs to be done on the GC alloc regions
332 // before a Full GC.
333 void abandon_gc_alloc_regions();
334
335 // Helper for monitoring and management support.
336 G1MonitoringSupport* _g1mm;
337
338 // Determines PLAB size for a particular allocation purpose.
339 size_t desired_plab_sz(GCAllocPurpose purpose);
340
341 // Outside of GC pauses, the number of bytes used in all regions other
342 // than the current allocation region.
343 size_t _summary_bytes_used;
344
345 // This is used for a quick test on whether a reference points into
346 // the collection set or not. Basically, we have an array, with one
347 // byte per region, and that byte denotes whether the corresponding
348 // region is in the collection set or not. The entry corresponding
349 // the bottom of the heap, i.e., region 0, is pointed to by
350 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
351 // biased so that it actually points to address 0 of the address
352 // space, to make the test as fast as possible (we can simply shift
353 // the address to address into it, instead of having to subtract the
354 // bottom of the heap from the address before shifting it; basically
355 // it works in the same way the card table works).
356 bool* _in_cset_fast_test;
357
358 // The allocated array used for the fast test on whether a reference
359 // points into the collection set or not. This field is also used to
360 // free the array.
361 bool* _in_cset_fast_test_base;
362
363 // The length of the _in_cset_fast_test_base array.
364 uint _in_cset_fast_test_length;
365
366 volatile unsigned _gc_time_stamp;
367
368 size_t* _surviving_young_words;
369
370 G1HRPrinter _hr_printer;
371
372 void setup_surviving_young_words();
373 void update_surviving_young_words(size_t* surv_young_words);
374 void cleanup_surviving_young_words();
375
376 // It decides whether an explicit GC should start a concurrent cycle
377 // instead of doing a STW GC. Currently, a concurrent cycle is
378 // explicitly started if:
379 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
380 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
381 // (c) cause == _g1_humongous_allocation
382 bool should_do_concurrent_full_gc(GCCause::Cause cause);
383
384 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
385 // concurrent cycles) we have started.
386 volatile unsigned int _old_marking_cycles_started;
387
388 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
389 // concurrent cycles) we have completed.
390 volatile unsigned int _old_marking_cycles_completed;
391
392 // This is a non-product method that is helpful for testing. It is
393 // called at the end of a GC and artificially expands the heap by
394 // allocating a number of dead regions. This way we can induce very
395 // frequent marking cycles and stress the cleanup / concurrent
396 // cleanup code more (as all the regions that will be allocated by
397 // this method will be found dead by the marking cycle).
398 void allocate_dummy_regions() PRODUCT_RETURN;
399
400 // Clear RSets after a compaction. It also resets the GC time stamps.
401 void clear_rsets_post_compaction();
402
403 // If the HR printer is active, dump the state of the regions in the
404 // heap after a compaction.
405 void print_hrs_post_compaction();
406
407 double verify(bool guard, const char* msg);
408 void verify_before_gc();
409 void verify_after_gc();
410
411 void log_gc_header();
412 void log_gc_footer(double pause_time_sec);
413
414 // These are macros so that, if the assert fires, we get the correct
415 // line number, file, etc.
416
417 #define heap_locking_asserts_err_msg(_extra_message_) \
418 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
419 (_extra_message_), \
420 BOOL_TO_STR(Heap_lock->owned_by_self()), \
421 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
422 BOOL_TO_STR(Thread::current()->is_VM_thread()))
423
424 #define assert_heap_locked() \
425 do { \
426 assert(Heap_lock->owned_by_self(), \
427 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
428 } while (0)
429
430 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
431 do { \
432 assert(Heap_lock->owned_by_self() || \
433 (SafepointSynchronize::is_at_safepoint() && \
434 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
435 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
436 "should be at a safepoint")); \
437 } while (0)
438
439 #define assert_heap_locked_and_not_at_safepoint() \
440 do { \
441 assert(Heap_lock->owned_by_self() && \
442 !SafepointSynchronize::is_at_safepoint(), \
443 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
444 "should not be at a safepoint")); \
445 } while (0)
446
447 #define assert_heap_not_locked() \
448 do { \
449 assert(!Heap_lock->owned_by_self(), \
450 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
451 } while (0)
452
453 #define assert_heap_not_locked_and_not_at_safepoint() \
454 do { \
455 assert(!Heap_lock->owned_by_self() && \
456 !SafepointSynchronize::is_at_safepoint(), \
457 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
458 "should not be at a safepoint")); \
459 } while (0)
460
461 #define assert_at_safepoint(_should_be_vm_thread_) \
462 do { \
463 assert(SafepointSynchronize::is_at_safepoint() && \
464 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
465 heap_locking_asserts_err_msg("should be at a safepoint")); \
466 } while (0)
467
468 #define assert_not_at_safepoint() \
469 do { \
470 assert(!SafepointSynchronize::is_at_safepoint(), \
471 heap_locking_asserts_err_msg("should not be at a safepoint")); \
472 } while (0)
473
474 protected:
475
476 // The young region list.
477 YoungList* _young_list;
478
479 // The current policy object for the collector.
480 G1CollectorPolicy* _g1_policy;
481
482 // This is the second level of trying to allocate a new region. If
483 // new_region() didn't find a region on the free_list, this call will
484 // check whether there's anything available on the
485 // secondary_free_list and/or wait for more regions to appear on
486 // that list, if _free_regions_coming is set.
487 HeapRegion* new_region_try_secondary_free_list();
488
489 // Try to allocate a single non-humongous HeapRegion sufficient for
490 // an allocation of the given word_size. If do_expand is true,
491 // attempt to expand the heap if necessary to satisfy the allocation
492 // request.
493 HeapRegion* new_region(size_t word_size, bool do_expand);
494
495 // Attempt to satisfy a humongous allocation request of the given
496 // size by finding a contiguous set of free regions of num_regions
497 // length and remove them from the master free list. Return the
498 // index of the first region or G1_NULL_HRS_INDEX if the search
499 // was unsuccessful.
500 uint humongous_obj_allocate_find_first(uint num_regions,
501 size_t word_size);
502
503 // Initialize a contiguous set of free regions of length num_regions
504 // and starting at index first so that they appear as a single
505 // humongous region.
506 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
507 uint num_regions,
508 size_t word_size);
509
510 // Attempt to allocate a humongous object of the given size. Return
511 // NULL if unsuccessful.
512 HeapWord* humongous_obj_allocate(size_t word_size);
513
514 // The following two methods, allocate_new_tlab() and
515 // mem_allocate(), are the two main entry points from the runtime
516 // into the G1's allocation routines. They have the following
517 // assumptions:
518 //
519 // * They should both be called outside safepoints.
520 //
521 // * They should both be called without holding the Heap_lock.
522 //
523 // * All allocation requests for new TLABs should go to
524 // allocate_new_tlab().
525 //
526 // * All non-TLAB allocation requests should go to mem_allocate().
527 //
528 // * If either call cannot satisfy the allocation request using the
529 // current allocating region, they will try to get a new one. If
530 // this fails, they will attempt to do an evacuation pause and
531 // retry the allocation.
532 //
533 // * If all allocation attempts fail, even after trying to schedule
534 // an evacuation pause, allocate_new_tlab() will return NULL,
535 // whereas mem_allocate() will attempt a heap expansion and/or
536 // schedule a Full GC.
537 //
538 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
539 // should never be called with word_size being humongous. All
540 // humongous allocation requests should go to mem_allocate() which
541 // will satisfy them with a special path.
542
543 virtual HeapWord* allocate_new_tlab(size_t word_size);
544
545 virtual HeapWord* mem_allocate(size_t word_size,
546 bool* gc_overhead_limit_was_exceeded);
547
548 // The following three methods take a gc_count_before_ret
549 // parameter which is used to return the GC count if the method
550 // returns NULL. Given that we are required to read the GC count
551 // while holding the Heap_lock, and these paths will take the
552 // Heap_lock at some point, it's easier to get them to read the GC
553 // count while holding the Heap_lock before they return NULL instead
554 // of the caller (namely: mem_allocate()) having to also take the
555 // Heap_lock just to read the GC count.
556
557 // First-level mutator allocation attempt: try to allocate out of
558 // the mutator alloc region without taking the Heap_lock. This
559 // should only be used for non-humongous allocations.
560 inline HeapWord* attempt_allocation(size_t word_size,
561 unsigned int* gc_count_before_ret,
562 int* gclocker_retry_count_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 int* gclocker_retry_count_ret);
570
571 // Takes the Heap_lock and attempts a humongous allocation. It can
572 // potentially schedule a GC pause.
573 HeapWord* attempt_allocation_humongous(size_t word_size,
574 unsigned int* gc_count_before_ret,
575 int* gclocker_retry_count_ret);
576
577 // Allocation attempt that should be called during safepoints (e.g.,
578 // at the end of a successful GC). expect_null_mutator_alloc_region
579 // specifies whether the mutator alloc region is expected to be NULL
580 // or not.
581 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
582 bool expect_null_mutator_alloc_region);
583
584 // It dirties the cards that cover the block so that so that the post
585 // write barrier never queues anything when updating objects on this
586 // block. It is assumed (and in fact we assert) that the block
587 // belongs to a young region.
588 inline void dirty_young_block(HeapWord* start, size_t word_size);
589
590 // Allocate blocks during garbage collection. Will ensure an
591 // allocation region, either by picking one or expanding the
592 // heap, and then allocate a block of the given size. The block
593 // may not be a humongous - it must fit into a single heap region.
594 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
595
596 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
597 HeapRegion* alloc_region,
598 bool par,
599 size_t word_size);
600
601 // Ensure that no further allocations can happen in "r", bearing in mind
602 // that parallel threads might be attempting allocations.
603 void par_allocate_remaining_space(HeapRegion* r);
604
605 // Allocation attempt during GC for a survivor object / PLAB.
606 inline HeapWord* survivor_attempt_allocation(size_t word_size);
607
608 // Allocation attempt during GC for an old object / PLAB.
609 inline HeapWord* old_attempt_allocation(size_t word_size);
610
611 // These methods are the "callbacks" from the G1AllocRegion class.
612
613 // For mutator alloc regions.
614 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
615 void retire_mutator_alloc_region(HeapRegion* alloc_region,
616 size_t allocated_bytes);
617
618 // For GC alloc regions.
619 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
620 GCAllocPurpose ap);
621 void retire_gc_alloc_region(HeapRegion* alloc_region,
622 size_t allocated_bytes, GCAllocPurpose ap);
623
624 // - if explicit_gc is true, the GC is for a System.gc() or a heap
625 // inspection request and should collect the entire heap
626 // - if clear_all_soft_refs is true, all soft references should be
627 // cleared during the GC
628 // - if explicit_gc is false, word_size describes the allocation that
629 // the GC should attempt (at least) to satisfy
630 // - it returns false if it is unable to do the collection due to the
631 // GC locker being active, true otherwise
632 bool do_collection(bool explicit_gc,
633 bool clear_all_soft_refs,
634 size_t word_size);
635
636 // Callback from VM_G1CollectFull operation.
637 // Perform a full collection.
638 virtual void do_full_collection(bool clear_all_soft_refs);
639
640 // Resize the heap if necessary after a full collection. If this is
641 // after a collect-for allocation, "word_size" is the allocation size,
642 // and will be considered part of the used portion of the heap.
643 void resize_if_necessary_after_full_collection(size_t word_size);
644
645 // Callback from VM_G1CollectForAllocation operation.
646 // This function does everything necessary/possible to satisfy a
647 // failed allocation request (including collection, expansion, etc.)
648 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
649
650 // Attempting to expand the heap sufficiently
651 // to support an allocation of the given "word_size". If
652 // successful, perform the allocation and return the address of the
653 // allocated block, or else "NULL".
654 HeapWord* expand_and_allocate(size_t word_size);
655
656 // Process any reference objects discovered during
657 // an incremental evacuation pause.
658 void process_discovered_references(uint no_of_gc_workers);
659
660 // Enqueue any remaining discovered references
661 // after processing.
662 void enqueue_discovered_references(uint no_of_gc_workers);
663
664 public:
665
666 G1MonitoringSupport* g1mm() {
667 assert(_g1mm != NULL, "should have been initialized");
668 return _g1mm;
669 }
670
671 // Expand the garbage-first heap by at least the given size (in bytes!).
672 // Returns true if the heap was expanded by the requested amount;
673 // false otherwise.
674 // (Rounds up to a HeapRegion boundary.)
675 bool expand(size_t expand_bytes);
676
677 // Do anything common to GC's.
678 virtual void gc_prologue(bool full);
679 virtual void gc_epilogue(bool full);
680
681 // We register a region with the fast "in collection set" test. We
682 // simply set to true the array slot corresponding to this region.
683 void register_region_with_in_cset_fast_test(HeapRegion* r) {
684 assert(_in_cset_fast_test_base != NULL, "sanity");
685 assert(r->in_collection_set(), "invariant");
686 uint index = r->hrs_index();
687 assert(index < _in_cset_fast_test_length, "invariant");
688 assert(!_in_cset_fast_test_base[index], "invariant");
689 _in_cset_fast_test_base[index] = true;
690 }
691
692 // This is a fast test on whether a reference points into the
693 // collection set or not. It does not assume that the reference
694 // points into the heap; if it doesn't, it will return false.
695 bool in_cset_fast_test(oop obj) {
696 assert(_in_cset_fast_test != NULL, "sanity");
697 if (_g1_committed.contains((HeapWord*) obj)) {
698 // no need to subtract the bottom of the heap from obj,
699 // _in_cset_fast_test is biased
700 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
701 bool ret = _in_cset_fast_test[index];
702 // let's make sure the result is consistent with what the slower
703 // test returns
704 assert( ret || !obj_in_cs(obj), "sanity");
705 assert(!ret || obj_in_cs(obj), "sanity");
706 return ret;
707 } else {
708 return false;
709 }
710 }
711
712 void clear_cset_fast_test() {
713 assert(_in_cset_fast_test_base != NULL, "sanity");
714 memset(_in_cset_fast_test_base, false,
715 (size_t) _in_cset_fast_test_length * sizeof(bool));
716 }
717
718 // This is called at the start of either a concurrent cycle or a Full
719 // GC to update the number of old marking cycles started.
720 void increment_old_marking_cycles_started();
721
722 // This is called at the end of either a concurrent cycle or a Full
723 // GC to update the number of old marking cycles completed. Those two
724 // can happen in a nested fashion, i.e., we start a concurrent
725 // cycle, a Full GC happens half-way through it which ends first,
726 // and then the cycle notices that a Full GC happened and ends
727 // too. The concurrent parameter is a boolean to help us do a bit
728 // tighter consistency checking in the method. If concurrent is
729 // false, the caller is the inner caller in the nesting (i.e., the
730 // Full GC). If concurrent is true, the caller is the outer caller
731 // in this nesting (i.e., the concurrent cycle). Further nesting is
732 // not currently supported. The end of this call also notifies
733 // the FullGCCount_lock in case a Java thread is waiting for a full
734 // GC to happen (e.g., it called System.gc() with
735 // +ExplicitGCInvokesConcurrent).
736 void increment_old_marking_cycles_completed(bool concurrent);
737
738 unsigned int old_marking_cycles_completed() {
739 return _old_marking_cycles_completed;
740 }
741
742 G1HRPrinter* hr_printer() { return &_hr_printer; }
743
744 protected:
745
746 // Shrink the garbage-first heap by at most the given size (in bytes!).
747 // (Rounds down to a HeapRegion boundary.)
748 virtual void shrink(size_t expand_bytes);
749 void shrink_helper(size_t expand_bytes);
750
751 #if TASKQUEUE_STATS
752 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
753 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
754 void reset_taskqueue_stats();
755 #endif // TASKQUEUE_STATS
756
757 // Schedule the VM operation that will do an evacuation pause to
758 // satisfy an allocation request of word_size. *succeeded will
759 // return whether the VM operation was successful (it did do an
760 // evacuation pause) or not (another thread beat us to it or the GC
761 // locker was active). Given that we should not be holding the
762 // Heap_lock when we enter this method, we will pass the
763 // gc_count_before (i.e., total_collections()) as a parameter since
764 // it has to be read while holding the Heap_lock. Currently, both
765 // methods that call do_collection_pause() release the Heap_lock
766 // before the call, so it's easy to read gc_count_before just before.
767 HeapWord* do_collection_pause(size_t word_size,
768 unsigned int gc_count_before,
769 bool* succeeded);
770
771 // The guts of the incremental collection pause, executed by the vm
772 // thread. It returns false if it is unable to do the collection due
773 // to the GC locker being active, true otherwise
774 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
775
776 // Actually do the work of evacuating the collection set.
777 void evacuate_collection_set();
778
779 // The g1 remembered set of the heap.
780 G1RemSet* _g1_rem_set;
781 // And it's mod ref barrier set, used to track updates for the above.
782 ModRefBarrierSet* _mr_bs;
783
784 // A set of cards that cover the objects for which the Rsets should be updated
785 // concurrently after the collection.
786 DirtyCardQueueSet _dirty_card_queue_set;
787
788 // The closure used to refine a single card.
789 RefineCardTableEntryClosure* _refine_cte_cl;
790
791 // A function to check the consistency of dirty card logs.
792 void check_ct_logs_at_safepoint();
793
794 // A DirtyCardQueueSet that is used to hold cards that contain
795 // references into the current collection set. This is used to
796 // update the remembered sets of the regions in the collection
797 // set in the event of an evacuation failure.
798 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
799
800 // After a collection pause, make the regions in the CS into free
801 // regions.
802 void free_collection_set(HeapRegion* cs_head);
803
804 // Abandon the current collection set without recording policy
805 // statistics or updating free lists.
806 void abandon_collection_set(HeapRegion* cs_head);
807
808 // Applies "scan_non_heap_roots" to roots outside the heap,
809 // "scan_rs" to roots inside the heap (having done "set_region" to
810 // indicate the region in which the root resides),
811 // and does "scan_metadata" If "scan_rs" is
812 // NULL, then this step is skipped. The "worker_i"
813 // param is for use with parallel roots processing, and should be
814 // the "i" of the calling parallel worker thread's work(i) function.
815 // In the sequential case this param will be ignored.
816 void g1_process_strong_roots(bool is_scavenging,
817 ScanningOption so,
818 OopClosure* scan_non_heap_roots,
819 OopsInHeapRegionClosure* scan_rs,
820 G1KlassScanClosure* scan_klasses,
821 int worker_i);
822
823 // Apply "blk" to all the weak roots of the system. These include
824 // JNI weak roots, the code cache, system dictionary, symbol table,
825 // string table, and referents of reachable weak refs.
826 void g1_process_weak_roots(OopClosure* root_closure);
827
828 // Frees a non-humongous region by initializing its contents and
829 // adding it to the free list that's passed as a parameter (this is
830 // usually a local list which will be appended to the master free
831 // list later). The used bytes of freed regions are accumulated in
832 // pre_used. If par is true, the region's RSet will not be freed
833 // up. The assumption is that this will be done later.
834 void free_region(HeapRegion* hr,
835 size_t* pre_used,
836 FreeRegionList* free_list,
837 bool par);
838
839 // Frees a humongous region by collapsing it into individual regions
840 // and calling free_region() for each of them. The freed regions
841 // will be added to the free list that's passed as a parameter (this
842 // is usually a local list which will be appended to the master free
843 // list later). The used bytes of freed regions are accumulated in
844 // pre_used. If par is true, the region's RSet will not be freed
845 // up. The assumption is that this will be done later.
846 void free_humongous_region(HeapRegion* hr,
847 size_t* pre_used,
848 FreeRegionList* free_list,
849 HumongousRegionSet* humongous_proxy_set,
850 bool par);
851
852 // Notifies all the necessary spaces that the committed space has
853 // been updated (either expanded or shrunk). It should be called
854 // after _g1_storage is updated.
855 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
856
857 // The concurrent marker (and the thread it runs in.)
858 ConcurrentMark* _cm;
859 ConcurrentMarkThread* _cmThread;
860 bool _mark_in_progress;
861
862 // The concurrent refiner.
863 ConcurrentG1Refine* _cg1r;
864
865 // The parallel task queues
866 RefToScanQueueSet *_task_queues;
867
868 // True iff a evacuation has failed in the current collection.
869 bool _evacuation_failed;
870
871 // Set the attribute indicating whether evacuation has failed in the
872 // current collection.
873 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
874
875 // Failed evacuations cause some logical from-space objects to have
876 // forwarding pointers to themselves. Reset them.
877 void remove_self_forwarding_pointers();
878
879 // Together, these store an object with a preserved mark, and its mark value.
880 Stack<oop, mtGC> _objs_with_preserved_marks;
881 Stack<markOop, mtGC> _preserved_marks_of_objs;
882
883 // Preserve the mark of "obj", if necessary, in preparation for its mark
884 // word being overwritten with a self-forwarding-pointer.
885 void preserve_mark_if_necessary(oop obj, markOop m);
886
887 // The stack of evac-failure objects left to be scanned.
888 GrowableArray<oop>* _evac_failure_scan_stack;
889 // The closure to apply to evac-failure objects.
890
891 OopsInHeapRegionClosure* _evac_failure_closure;
892 // Set the field above.
893 void
894 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
895 _evac_failure_closure = evac_failure_closure;
896 }
897
898 // Push "obj" on the scan stack.
899 void push_on_evac_failure_scan_stack(oop obj);
900 // Process scan stack entries until the stack is empty.
901 void drain_evac_failure_scan_stack();
902 // True iff an invocation of "drain_scan_stack" is in progress; to
903 // prevent unnecessary recursion.
904 bool _drain_in_progress;
905
906 // Do any necessary initialization for evacuation-failure handling.
907 // "cl" is the closure that will be used to process evac-failure
908 // objects.
909 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
910 // Do any necessary cleanup for evacuation-failure handling data
911 // structures.
912 void finalize_for_evac_failure();
913
914 // An attempt to evacuate "obj" has failed; take necessary steps.
915 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
916 void handle_evacuation_failure_common(oop obj, markOop m);
917
918 #ifndef PRODUCT
919 // Support for forcing evacuation failures. Analogous to
920 // PromotionFailureALot for the other collectors.
921
922 // Records whether G1EvacuationFailureALot should be in effect
923 // for the current GC
924 bool _evacuation_failure_alot_for_current_gc;
925
926 // Used to record the GC number for interval checking when
927 // determining whether G1EvaucationFailureALot is in effect
928 // for the current GC.
929 size_t _evacuation_failure_alot_gc_number;
930
931 // Count of the number of evacuations between failures.
932 volatile size_t _evacuation_failure_alot_count;
933
934 // Set whether G1EvacuationFailureALot should be in effect
935 // for the current GC (based upon the type of GC and which
936 // command line flags are set);
937 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
938 bool during_initial_mark,
939 bool during_marking);
940
941 inline void set_evacuation_failure_alot_for_current_gc();
942
943 // Return true if it's time to cause an evacuation failure.
944 inline bool evacuation_should_fail();
945
946 // Reset the G1EvacuationFailureALot counters. Should be called at
947 // the end of an evacuation pause in which an evacuation failure ocurred.
948 inline void reset_evacuation_should_fail();
949 #endif // !PRODUCT
950
951 // ("Weak") Reference processing support.
952 //
953 // G1 has 2 instances of the referece processor class. One
954 // (_ref_processor_cm) handles reference object discovery
955 // and subsequent processing during concurrent marking cycles.
956 //
957 // The other (_ref_processor_stw) handles reference object
958 // discovery and processing during full GCs and incremental
959 // evacuation pauses.
960 //
961 // During an incremental pause, reference discovery will be
962 // temporarily disabled for _ref_processor_cm and will be
963 // enabled for _ref_processor_stw. At the end of the evacuation
964 // pause references discovered by _ref_processor_stw will be
965 // processed and discovery will be disabled. The previous
966 // setting for reference object discovery for _ref_processor_cm
967 // will be re-instated.
968 //
969 // At the start of marking:
970 // * Discovery by the CM ref processor is verified to be inactive
971 // and it's discovered lists are empty.
972 // * Discovery by the CM ref processor is then enabled.
973 //
974 // At the end of marking:
975 // * Any references on the CM ref processor's discovered
976 // lists are processed (possibly MT).
977 //
978 // At the start of full GC we:
979 // * Disable discovery by the CM ref processor and
980 // empty CM ref processor's discovered lists
981 // (without processing any entries).
982 // * Verify that the STW ref processor is inactive and it's
983 // discovered lists are empty.
984 // * Temporarily set STW ref processor discovery as single threaded.
985 // * Temporarily clear the STW ref processor's _is_alive_non_header
986 // field.
987 // * Finally enable discovery by the STW ref processor.
988 //
989 // The STW ref processor is used to record any discovered
990 // references during the full GC.
991 //
992 // At the end of a full GC we:
993 // * Enqueue any reference objects discovered by the STW ref processor
994 // that have non-live referents. This has the side-effect of
995 // making the STW ref processor inactive by disabling discovery.
996 // * Verify that the CM ref processor is still inactive
997 // and no references have been placed on it's discovered
998 // lists (also checked as a precondition during initial marking).
999
1000 // The (stw) reference processor...
1001 ReferenceProcessor* _ref_processor_stw;
1002
1003 // During reference object discovery, the _is_alive_non_header
1004 // closure (if non-null) is applied to the referent object to
1005 // determine whether the referent is live. If so then the
1006 // reference object does not need to be 'discovered' and can
1007 // be treated as a regular oop. This has the benefit of reducing
1008 // the number of 'discovered' reference objects that need to
1009 // be processed.
1010 //
1011 // Instance of the is_alive closure for embedding into the
1012 // STW reference processor as the _is_alive_non_header field.
1013 // Supplying a value for the _is_alive_non_header field is
1014 // optional but doing so prevents unnecessary additions to
1015 // the discovered lists during reference discovery.
1016 G1STWIsAliveClosure _is_alive_closure_stw;
1017
1018 // The (concurrent marking) reference processor...
1019 ReferenceProcessor* _ref_processor_cm;
1020
1021 // Instance of the concurrent mark is_alive closure for embedding
1022 // into the Concurrent Marking reference processor as the
1023 // _is_alive_non_header field. Supplying a value for the
1024 // _is_alive_non_header field is optional but doing so prevents
1025 // unnecessary additions to the discovered lists during reference
1026 // discovery.
1027 G1CMIsAliveClosure _is_alive_closure_cm;
1028
1029 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1030 HeapRegion** _worker_cset_start_region;
1031
1032 // Time stamp to validate the regions recorded in the cache
1033 // used by G1CollectedHeap::start_cset_region_for_worker().
1034 // The heap region entry for a given worker is valid iff
1035 // the associated time stamp value matches the current value
1036 // of G1CollectedHeap::_gc_time_stamp.
1037 unsigned int* _worker_cset_start_region_time_stamp;
1038
1039 enum G1H_process_strong_roots_tasks {
1040 G1H_PS_filter_satb_buffers,
1041 G1H_PS_refProcessor_oops_do,
1042 // Leave this one last.
1043 G1H_PS_NumElements
1044 };
1045
1046 SubTasksDone* _process_strong_tasks;
1047
1048 volatile bool _free_regions_coming;
1049
1050 public:
1051
1052 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1053
1054 void set_refine_cte_cl_concurrency(bool concurrent);
1055
1056 RefToScanQueue *task_queue(int i) const;
1057
1058 // A set of cards where updates happened during the GC
1059 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1060
1061 // A DirtyCardQueueSet that is used to hold cards that contain
1062 // references into the current collection set. This is used to
1063 // update the remembered sets of the regions in the collection
1064 // set in the event of an evacuation failure.
1065 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1066 { return _into_cset_dirty_card_queue_set; }
1067
1068 // Create a G1CollectedHeap with the specified policy.
1069 // Must call the initialize method afterwards.
1070 // May not return if something goes wrong.
1071 G1CollectedHeap(G1CollectorPolicy* policy);
1072
1073 // Initialize the G1CollectedHeap to have the initial and
1074 // maximum sizes and remembered and barrier sets
1075 // specified by the policy object.
1076 jint initialize();
1077
1078 // Initialize weak reference processing.
1079 virtual void ref_processing_init();
1080
1081 void set_par_threads(uint t) {
1082 SharedHeap::set_par_threads(t);
1083 // Done in SharedHeap but oddly there are
1084 // two _process_strong_tasks's in a G1CollectedHeap
1085 // so do it here too.
1086 _process_strong_tasks->set_n_threads(t);
1087 }
1088
1089 // Set _n_par_threads according to a policy TBD.
1090 void set_par_threads();
1091
1092 void set_n_termination(int t) {
1093 _process_strong_tasks->set_n_threads(t);
1094 }
1095
1096 virtual CollectedHeap::Name kind() const {
1097 return CollectedHeap::G1CollectedHeap;
1098 }
1099
1100 // The current policy object for the collector.
1101 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1102
1103 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1104
1105 // Adaptive size policy. No such thing for g1.
1106 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1107
1108 // The rem set and barrier set.
1109 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1110 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1111
1112 unsigned get_gc_time_stamp() {
1113 return _gc_time_stamp;
1114 }
1115
1116 void reset_gc_time_stamp() {
1117 _gc_time_stamp = 0;
1118 OrderAccess::fence();
1119 // Clear the cached CSet starting regions and time stamps.
1120 // Their validity is dependent on the GC timestamp.
1121 clear_cset_start_regions();
1122 }
1123
1124 void check_gc_time_stamps() PRODUCT_RETURN;
1125
1126 void increment_gc_time_stamp() {
1127 ++_gc_time_stamp;
1128 OrderAccess::fence();
1129 }
1130
1131 // Reset the given region's GC timestamp. If it's starts humongous,
1132 // also reset the GC timestamp of its corresponding
1133 // continues humongous regions too.
1134 void reset_gc_time_stamps(HeapRegion* hr);
1135
1136 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1137 DirtyCardQueue* into_cset_dcq,
1138 bool concurrent, int worker_i);
1139
1140 // The shared block offset table array.
1141 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1142
1143 // Reference Processing accessors
1144
1145 // The STW reference processor....
1146 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1147
1148 // The Concurent Marking reference processor...
1149 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1150
1151 virtual size_t capacity() const;
1152 virtual size_t used() const;
1153 // This should be called when we're not holding the heap lock. The
1154 // result might be a bit inaccurate.
1155 size_t used_unlocked() const;
1156 size_t recalculate_used() const;
1157
1158 // These virtual functions do the actual allocation.
1159 // Some heaps may offer a contiguous region for shared non-blocking
1160 // allocation, via inlined code (by exporting the address of the top and
1161 // end fields defining the extent of the contiguous allocation region.)
1162 // But G1CollectedHeap doesn't yet support this.
1163
1164 // Return an estimate of the maximum allocation that could be performed
1165 // without triggering any collection or expansion activity. In a
1166 // generational collector, for example, this is probably the largest
1167 // allocation that could be supported (without expansion) in the youngest
1168 // generation. It is "unsafe" because no locks are taken; the result
1169 // should be treated as an approximation, not a guarantee, for use in
1170 // heuristic resizing decisions.
1171 virtual size_t unsafe_max_alloc();
1172
1173 virtual bool is_maximal_no_gc() const {
1174 return _g1_storage.uncommitted_size() == 0;
1175 }
1176
1177 // The total number of regions in the heap.
1178 uint n_regions() { return _hrs.length(); }
1179
1180 // The max number of regions in the heap.
1181 uint max_regions() { return _hrs.max_length(); }
1182
1183 // The number of regions that are completely free.
1184 uint free_regions() { return _free_list.length(); }
1185
1186 // The number of regions that are not completely free.
1187 uint used_regions() { return n_regions() - free_regions(); }
1188
1189 // The number of regions available for "regular" expansion.
1190 uint expansion_regions() { return _expansion_regions; }
1191
1192 // Factory method for HeapRegion instances. It will return NULL if
1193 // the allocation fails.
1194 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1195
1196 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1197 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1198 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1199 void verify_dirty_young_regions() PRODUCT_RETURN;
1200
1201 // verify_region_sets() performs verification over the region
1202 // lists. It will be compiled in the product code to be used when
1203 // necessary (i.e., during heap verification).
1204 void verify_region_sets();
1205
1206 // verify_region_sets_optional() is planted in the code for
1207 // list verification in non-product builds (and it can be enabled in
1208 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1209 #if HEAP_REGION_SET_FORCE_VERIFY
1210 void verify_region_sets_optional() {
1211 verify_region_sets();
1212 }
1213 #else // HEAP_REGION_SET_FORCE_VERIFY
1214 void verify_region_sets_optional() { }
1215 #endif // HEAP_REGION_SET_FORCE_VERIFY
1216
1217 #ifdef ASSERT
1218 bool is_on_master_free_list(HeapRegion* hr) {
1219 return hr->containing_set() == &_free_list;
1220 }
1221
1222 bool is_in_humongous_set(HeapRegion* hr) {
1223 return hr->containing_set() == &_humongous_set;
1224 }
1225 #endif // ASSERT
1226
1227 // Wrapper for the region list operations that can be called from
1228 // methods outside this class.
1229
1230 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1231 _secondary_free_list.add_as_tail(list);
1232 }
1233
1234 void append_secondary_free_list() {
1235 _free_list.add_as_head(&_secondary_free_list);
1236 }
1237
1238 void append_secondary_free_list_if_not_empty_with_lock() {
1239 // If the secondary free list looks empty there's no reason to
1240 // take the lock and then try to append it.
1241 if (!_secondary_free_list.is_empty()) {
1242 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1243 append_secondary_free_list();
1244 }
1245 }
1246
1247 void old_set_remove(HeapRegion* hr) {
1248 _old_set.remove(hr);
1249 }
1250
1251 size_t non_young_capacity_bytes() {
1252 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1253 }
1254
1255 void set_free_regions_coming();
1256 void reset_free_regions_coming();
1257 bool free_regions_coming() { return _free_regions_coming; }
1258 void wait_while_free_regions_coming();
1259
1260 // Determine whether the given region is one that we are using as an
1261 // old GC alloc region.
1262 bool is_old_gc_alloc_region(HeapRegion* hr) {
1263 return hr == _retained_old_gc_alloc_region;
1264 }
1265
1266 // Perform a collection of the heap; intended for use in implementing
1267 // "System.gc". This probably implies as full a collection as the
1268 // "CollectedHeap" supports.
1269 virtual void collect(GCCause::Cause cause);
1270
1271 // The same as above but assume that the caller holds the Heap_lock.
1272 void collect_locked(GCCause::Cause cause);
1273
1274 // True iff a evacuation has failed in the most-recent collection.
1275 bool evacuation_failed() { return _evacuation_failed; }
1276
1277 // It will free a region if it has allocated objects in it that are
1278 // all dead. It calls either free_region() or
1279 // free_humongous_region() depending on the type of the region that
1280 // is passed to it.
1281 void free_region_if_empty(HeapRegion* hr,
1282 size_t* pre_used,
1283 FreeRegionList* free_list,
1284 OldRegionSet* old_proxy_set,
1285 HumongousRegionSet* humongous_proxy_set,
1286 HRRSCleanupTask* hrrs_cleanup_task,
1287 bool par);
1288
1289 // It appends the free list to the master free list and updates the
1290 // master humongous list according to the contents of the proxy
1291 // list. It also adjusts the total used bytes according to pre_used
1292 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1293 void update_sets_after_freeing_regions(size_t pre_used,
1294 FreeRegionList* free_list,
1295 OldRegionSet* old_proxy_set,
1296 HumongousRegionSet* humongous_proxy_set,
1297 bool par);
1298
1299 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1300 virtual bool is_in(const void* p) const;
1301
1302 // Return "TRUE" iff the given object address is within the collection
1303 // set.
1304 inline bool obj_in_cs(oop obj);
1305
1306 // Return "TRUE" iff the given object address is in the reserved
1307 // region of g1.
1308 bool is_in_g1_reserved(const void* p) const {
1309 return _g1_reserved.contains(p);
1310 }
1311
1312 // Returns a MemRegion that corresponds to the space that has been
1313 // reserved for the heap
1314 MemRegion g1_reserved() {
1315 return _g1_reserved;
1316 }
1317
1318 // Returns a MemRegion that corresponds to the space that has been
1319 // committed in the heap
1320 MemRegion g1_committed() {
1321 return _g1_committed;
1322 }
1323
1324 virtual bool is_in_closed_subset(const void* p) const;
1325
1326 // This resets the card table to all zeros. It is used after
1327 // a collection pause which used the card table to claim cards.
1328 void cleanUpCardTable();
1329
1330 // Iteration functions.
1331
1332 // Iterate over all the ref-containing fields of all objects, calling
1333 // "cl.do_oop" on each.
1334 virtual void oop_iterate(ExtendedOopClosure* cl);
1335
1336 // Same as above, restricted to a memory region.
1337 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1338
1339 // Iterate over all objects, calling "cl.do_object" on each.
1340 virtual void object_iterate(ObjectClosure* cl);
1341
1342 virtual void safe_object_iterate(ObjectClosure* cl) {
1343 object_iterate(cl);
1344 }
1345
1346 // Iterate over all objects allocated since the last collection, calling
1347 // "cl.do_object" on each. The heap must have been initialized properly
1348 // to support this function, or else this call will fail.
1349 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1350
1351 // Iterate over all spaces in use in the heap, in ascending address order.
1352 virtual void space_iterate(SpaceClosure* cl);
1353
1354 // Iterate over heap regions, in address order, terminating the
1355 // iteration early if the "doHeapRegion" method returns "true".
1356 void heap_region_iterate(HeapRegionClosure* blk) const;
1357
1358 // Return the region with the given index. It assumes the index is valid.
1359 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1360
1361 // Divide the heap region sequence into "chunks" of some size (the number
1362 // of regions divided by the number of parallel threads times some
1363 // overpartition factor, currently 4). Assumes that this will be called
1364 // in parallel by ParallelGCThreads worker threads with discinct worker
1365 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1366 // calls will use the same "claim_value", and that that claim value is
1367 // different from the claim_value of any heap region before the start of
1368 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1369 // attempting to claim the first region in each chunk, and, if
1370 // successful, applying the closure to each region in the chunk (and
1371 // setting the claim value of the second and subsequent regions of the
1372 // chunk.) For now requires that "doHeapRegion" always returns "false",
1373 // i.e., that a closure never attempt to abort a traversal.
1374 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1375 uint worker,
1376 uint no_of_par_workers,
1377 jint claim_value);
1378
1379 // It resets all the region claim values to the default.
1380 void reset_heap_region_claim_values();
1381
1382 // Resets the claim values of regions in the current
1383 // collection set to the default.
1384 void reset_cset_heap_region_claim_values();
1385
1386 #ifdef ASSERT
1387 bool check_heap_region_claim_values(jint claim_value);
1388
1389 // Same as the routine above but only checks regions in the
1390 // current collection set.
1391 bool check_cset_heap_region_claim_values(jint claim_value);
1392 #endif // ASSERT
1393
1394 // Clear the cached cset start regions and (more importantly)
1395 // the time stamps. Called when we reset the GC time stamp.
1396 void clear_cset_start_regions();
1397
1398 // Given the id of a worker, obtain or calculate a suitable
1399 // starting region for iterating over the current collection set.
1400 HeapRegion* start_cset_region_for_worker(int worker_i);
1401
1402 // This is a convenience method that is used by the
1403 // HeapRegionIterator classes to calculate the starting region for
1404 // each worker so that they do not all start from the same region.
1405 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1406
1407 // Iterate over the regions (if any) in the current collection set.
1408 void collection_set_iterate(HeapRegionClosure* blk);
1409
1410 // As above but starting from region r
1411 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1412
1413 // Returns the first (lowest address) compactible space in the heap.
1414 virtual CompactibleSpace* first_compactible_space();
1415
1416 // A CollectedHeap will contain some number of spaces. This finds the
1417 // space containing a given address, or else returns NULL.
1418 virtual Space* space_containing(const void* addr) const;
1419
1420 // A G1CollectedHeap will contain some number of heap regions. This
1421 // finds the region containing a given address, or else returns NULL.
1422 template <class T>
1423 inline HeapRegion* heap_region_containing(const T addr) const;
1424
1425 // Like the above, but requires "addr" to be in the heap (to avoid a
1426 // null-check), and unlike the above, may return an continuing humongous
1427 // region.
1428 template <class T>
1429 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1430
1431 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1432 // each address in the (reserved) heap is a member of exactly
1433 // one block. The defining characteristic of a block is that it is
1434 // possible to find its size, and thus to progress forward to the next
1435 // block. (Blocks may be of different sizes.) Thus, blocks may
1436 // represent Java objects, or they might be free blocks in a
1437 // free-list-based heap (or subheap), as long as the two kinds are
1438 // distinguishable and the size of each is determinable.
1439
1440 // Returns the address of the start of the "block" that contains the
1441 // address "addr". We say "blocks" instead of "object" since some heaps
1442 // may not pack objects densely; a chunk may either be an object or a
1443 // non-object.
1444 virtual HeapWord* block_start(const void* addr) const;
1445
1446 // Requires "addr" to be the start of a chunk, and returns its size.
1447 // "addr + size" is required to be the start of a new chunk, or the end
1448 // of the active area of the heap.
1449 virtual size_t block_size(const HeapWord* addr) const;
1450
1451 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1452 // the block is an object.
1453 virtual bool block_is_obj(const HeapWord* addr) const;
1454
1455 // Does this heap support heap inspection? (+PrintClassHistogram)
1456 virtual bool supports_heap_inspection() const { return true; }
1457
1458 // Section on thread-local allocation buffers (TLABs)
1459 // See CollectedHeap for semantics.
1460
1461 virtual bool supports_tlab_allocation() const;
1462 virtual size_t tlab_capacity(Thread* thr) const;
1463 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1464
1465 // Can a compiler initialize a new object without store barriers?
1466 // This permission only extends from the creation of a new object
1467 // via a TLAB up to the first subsequent safepoint. If such permission
1468 // is granted for this heap type, the compiler promises to call
1469 // defer_store_barrier() below on any slow path allocation of
1470 // a new object for which such initializing store barriers will
1471 // have been elided. G1, like CMS, allows this, but should be
1472 // ready to provide a compensating write barrier as necessary
1473 // if that storage came out of a non-young region. The efficiency
1474 // of this implementation depends crucially on being able to
1475 // answer very efficiently in constant time whether a piece of
1476 // storage in the heap comes from a young region or not.
1477 // See ReduceInitialCardMarks.
1478 virtual bool can_elide_tlab_store_barriers() const {
1479 return true;
1480 }
1481
1482 virtual bool card_mark_must_follow_store() const {
1483 return true;
1484 }
1485
1486 bool is_in_young(const oop obj) {
1487 HeapRegion* hr = heap_region_containing(obj);
1488 return hr != NULL && hr->is_young();
1489 }
1490
1491 #ifdef ASSERT
1492 virtual bool is_in_partial_collection(const void* p);
1493 #endif
1494
1495 virtual bool is_scavengable(const void* addr);
1496
1497 // We don't need barriers for initializing stores to objects
1498 // in the young gen: for the SATB pre-barrier, there is no
1499 // pre-value that needs to be remembered; for the remembered-set
1500 // update logging post-barrier, we don't maintain remembered set
1501 // information for young gen objects.
1502 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1503 return is_in_young(new_obj);
1504 }
1505
1506 // Returns "true" iff the given word_size is "very large".
1507 static bool isHumongous(size_t word_size) {
1508 // Note this has to be strictly greater-than as the TLABs
1509 // are capped at the humongous thresold and we want to
1510 // ensure that we don't try to allocate a TLAB as
1511 // humongous and that we don't allocate a humongous
1512 // object in a TLAB.
1513 return word_size > _humongous_object_threshold_in_words;
1514 }
1515
1516 // Update mod union table with the set of dirty cards.
1517 void updateModUnion();
1518
1519 // Set the mod union bits corresponding to the given memRegion. Note
1520 // that this is always a safe operation, since it doesn't clear any
1521 // bits.
1522 void markModUnionRange(MemRegion mr);
1523
1524 // Records the fact that a marking phase is no longer in progress.
1525 void set_marking_complete() {
1526 _mark_in_progress = false;
1527 }
1528 void set_marking_started() {
1529 _mark_in_progress = true;
1530 }
1531 bool mark_in_progress() {
1532 return _mark_in_progress;
1533 }
1534
1535 // Print the maximum heap capacity.
1536 virtual size_t max_capacity() const;
1537
1538 virtual jlong millis_since_last_gc();
1539
1540 // Perform any cleanup actions necessary before allowing a verification.
1541 virtual void prepare_for_verify();
1542
1543 // Perform verification.
1544
1545 // vo == UsePrevMarking -> use "prev" marking information,
1546 // vo == UseNextMarking -> use "next" marking information
1547 // vo == UseMarkWord -> use the mark word in the object header
1548 //
1549 // NOTE: Only the "prev" marking information is guaranteed to be
1550 // consistent most of the time, so most calls to this should use
1551 // vo == UsePrevMarking.
1552 // Currently, there is only one case where this is called with
1553 // vo == UseNextMarking, which is to verify the "next" marking
1554 // information at the end of remark.
1555 // Currently there is only one place where this is called with
1556 // vo == UseMarkWord, which is to verify the marking during a
1557 // full GC.
1558 void verify(bool silent, VerifyOption vo);
1559
1560 // Override; it uses the "prev" marking information
1561 virtual void verify(bool silent);
1562 virtual void print_on(outputStream* st) const;
1563 virtual void print_extended_on(outputStream* st) const;
1564 virtual void print_on_error(outputStream* st) const;
1565
1566 virtual void print_gc_threads_on(outputStream* st) const;
1567 virtual void gc_threads_do(ThreadClosure* tc) const;
1568
1569 // Override
1570 void print_tracing_info() const;
1571
1572 // The following two methods are helpful for debugging RSet issues.
1573 void print_cset_rsets() PRODUCT_RETURN;
1574 void print_all_rsets() PRODUCT_RETURN;
1575
1576 // Convenience function to be used in situations where the heap type can be
1577 // asserted to be this type.
1578 static G1CollectedHeap* heap();
1579
1580 void set_region_short_lived_locked(HeapRegion* hr);
1581 // add appropriate methods for any other surv rate groups
1582
1583 YoungList* young_list() { return _young_list; }
1584
1585 // debugging
1586 bool check_young_list_well_formed() {
1587 return _young_list->check_list_well_formed();
1588 }
1589
1590 bool check_young_list_empty(bool check_heap,
1591 bool check_sample = true);
1592
1593 // *** Stuff related to concurrent marking. It's not clear to me that so
1594 // many of these need to be public.
1595
1596 // The functions below are helper functions that a subclass of
1597 // "CollectedHeap" can use in the implementation of its virtual
1598 // functions.
1599 // This performs a concurrent marking of the live objects in a
1600 // bitmap off to the side.
1601 void doConcurrentMark();
1602
1603 bool isMarkedPrev(oop obj) const;
1604 bool isMarkedNext(oop obj) const;
1605
1606 // Determine if an object is dead, given the object and also
1607 // the region to which the object belongs. An object is dead
1608 // iff a) it was not allocated since the last mark and b) it
1609 // is not marked.
1610
1611 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1612 return
1613 !hr->obj_allocated_since_prev_marking(obj) &&
1614 !isMarkedPrev(obj);
1615 }
1616
1617 // This function returns true when an object has been
1618 // around since the previous marking and hasn't yet
1619 // been marked during this marking.
1620
1621 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1622 return
1623 !hr->obj_allocated_since_next_marking(obj) &&
1624 !isMarkedNext(obj);
1625 }
1626
1627 // Determine if an object is dead, given only the object itself.
1628 // This will find the region to which the object belongs and
1629 // then call the region version of the same function.
1630
1631 // Added if it is NULL it isn't dead.
1632
1633 bool is_obj_dead(const oop obj) const {
1634 const HeapRegion* hr = heap_region_containing(obj);
1635 if (hr == NULL) {
1636 if (obj == NULL) return false;
1637 else return true;
1638 }
1639 else return is_obj_dead(obj, hr);
1640 }
1641
1642 bool is_obj_ill(const oop obj) const {
1643 const HeapRegion* hr = heap_region_containing(obj);
1644 if (hr == NULL) {
1645 if (obj == NULL) return false;
1646 else return true;
1647 }
1648 else return is_obj_ill(obj, hr);
1649 }
1650
1651 // The methods below are here for convenience and dispatch the
1652 // appropriate method depending on value of the given VerifyOption
1653 // parameter. The options for that parameter are:
1654 //
1655 // vo == UsePrevMarking -> use "prev" marking information,
1656 // vo == UseNextMarking -> use "next" marking information,
1657 // vo == UseMarkWord -> use mark word from object header
1658
1659 bool is_obj_dead_cond(const oop obj,
1660 const HeapRegion* hr,
1661 const VerifyOption vo) const {
1662 switch (vo) {
1663 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1664 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1665 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1666 default: ShouldNotReachHere();
1667 }
1668 return false; // keep some compilers happy
1669 }
1670
1671 bool is_obj_dead_cond(const oop obj,
1672 const VerifyOption vo) const {
1673 switch (vo) {
1674 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1675 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1676 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1677 default: ShouldNotReachHere();
1678 }
1679 return false; // keep some compilers happy
1680 }
1681
1682 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1683 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1684 bool is_marked(oop obj, VerifyOption vo);
1685 const char* top_at_mark_start_str(VerifyOption vo);
1686
1687 // The following is just to alert the verification code
1688 // that a full collection has occurred and that the
1689 // remembered sets are no longer up to date.
1690 bool _full_collection;
1691 void set_full_collection() { _full_collection = true;}
1692 void clear_full_collection() {_full_collection = false;}
1693 bool full_collection() {return _full_collection;}
1694
1695 ConcurrentMark* concurrent_mark() const { return _cm; }
1696 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1697
1698 // The dirty cards region list is used to record a subset of regions
1699 // whose cards need clearing. The list if populated during the
1700 // remembered set scanning and drained during the card table
1701 // cleanup. Although the methods are reentrant, population/draining
1702 // phases must not overlap. For synchronization purposes the last
1703 // element on the list points to itself.
1704 HeapRegion* _dirty_cards_region_list;
1705 void push_dirty_cards_region(HeapRegion* hr);
1706 HeapRegion* pop_dirty_cards_region();
1707
1708 public:
1709 void stop_conc_gc_threads();
1710
1711 size_t pending_card_num();
1712 size_t cards_scanned();
1713
1714 protected:
1715 size_t _max_heap_capacity;
1716 };
1717
1718 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1719 private:
1720 bool _retired;
1721
1722 public:
1723 G1ParGCAllocBuffer(size_t gclab_word_size);
1724
1725 void set_buf(HeapWord* buf) {
1726 ParGCAllocBuffer::set_buf(buf);
1727 _retired = false;
1728 }
1729
1730 void retire(bool end_of_gc, bool retain) {
1731 if (_retired)
1732 return;
1733 ParGCAllocBuffer::retire(end_of_gc, retain);
1734 _retired = true;
1735 }
1736 };
1737
1738 class G1ParScanThreadState : public StackObj {
1739 protected:
1740 G1CollectedHeap* _g1h;
1741 RefToScanQueue* _refs;
1742 DirtyCardQueue _dcq;
1743 CardTableModRefBS* _ct_bs;
1744 G1RemSet* _g1_rem;
1745
1746 G1ParGCAllocBuffer _surviving_alloc_buffer;
1747 G1ParGCAllocBuffer _tenured_alloc_buffer;
1748 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1749 ageTable _age_table;
1750
1751 size_t _alloc_buffer_waste;
1752 size_t _undo_waste;
1753
1754 OopsInHeapRegionClosure* _evac_failure_cl;
1755 G1ParScanHeapEvacClosure* _evac_cl;
1756 G1ParScanPartialArrayClosure* _partial_scan_cl;
1757
1758 int _hash_seed;
1759 uint _queue_num;
1760
1761 size_t _term_attempts;
1762
1763 double _start;
1764 double _start_strong_roots;
1765 double _strong_roots_time;
1766 double _start_term;
1767 double _term_time;
1768
1769 // Map from young-age-index (0 == not young, 1 is youngest) to
1770 // surviving words. base is what we get back from the malloc call
1771 size_t* _surviving_young_words_base;
1772 // this points into the array, as we use the first few entries for padding
1773 size_t* _surviving_young_words;
1774
1775 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1776
1777 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1778
1779 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1780
1781 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1782 CardTableModRefBS* ctbs() { return _ct_bs; }
1783
1784 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1785 if (!from->is_survivor()) {
1786 _g1_rem->par_write_ref(from, p, tid);
1787 }
1788 }
1789
1790 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1791 // If the new value of the field points to the same region or
1792 // is the to-space, we don't need to include it in the Rset updates.
1793 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1794 size_t card_index = ctbs()->index_for(p);
1795 // If the card hasn't been added to the buffer, do it.
1796 if (ctbs()->mark_card_deferred(card_index)) {
1797 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1798 }
1799 }
1800 }
1801
1802 public:
1803 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1804
1805 ~G1ParScanThreadState() {
1806 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1807 }
1808
1809 RefToScanQueue* refs() { return _refs; }
1810 ageTable* age_table() { return &_age_table; }
1811
1812 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1813 return _alloc_buffers[purpose];
1814 }
1815
1816 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1817 size_t undo_waste() const { return _undo_waste; }
1818
1819 #ifdef ASSERT
1820 bool verify_ref(narrowOop* ref) const;
1821 bool verify_ref(oop* ref) const;
1822 bool verify_task(StarTask ref) const;
1823 #endif // ASSERT
1824
1825 template <class T> void push_on_queue(T* ref) {
1826 assert(verify_ref(ref), "sanity");
1827 refs()->push(ref);
1828 }
1829
1830 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1831 if (G1DeferredRSUpdate) {
1832 deferred_rs_update(from, p, tid);
1833 } else {
1834 immediate_rs_update(from, p, tid);
1835 }
1836 }
1837
1838 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1839 HeapWord* obj = NULL;
1840 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1841 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1842 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1843 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1844 alloc_buf->retire(false /* end_of_gc */, false /* retain */);
1845
1846 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1847 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1848 // Otherwise.
1849 alloc_buf->set_word_size(gclab_word_size);
1850 alloc_buf->set_buf(buf);
1851
1852 obj = alloc_buf->allocate(word_sz);
1853 assert(obj != NULL, "buffer was definitely big enough...");
1854 } else {
1855 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1856 }
1857 return obj;
1858 }
1859
1860 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1861 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1862 if (obj != NULL) return obj;
1863 return allocate_slow(purpose, word_sz);
1864 }
1865
1866 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1867 if (alloc_buffer(purpose)->contains(obj)) {
1868 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1869 "should contain whole object");
1870 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1871 } else {
1872 CollectedHeap::fill_with_object(obj, word_sz);
1873 add_to_undo_waste(word_sz);
1874 }
1875 }
1876
1877 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1878 _evac_failure_cl = evac_failure_cl;
1879 }
1880 OopsInHeapRegionClosure* evac_failure_closure() {
1881 return _evac_failure_cl;
1882 }
1883
1884 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1885 _evac_cl = evac_cl;
1886 }
1887
1888 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1889 _partial_scan_cl = partial_scan_cl;
1890 }
1891
1892 int* hash_seed() { return &_hash_seed; }
1893 uint queue_num() { return _queue_num; }
1894
1895 size_t term_attempts() const { return _term_attempts; }
1896 void note_term_attempt() { _term_attempts++; }
1897
1898 void start_strong_roots() {
1899 _start_strong_roots = os::elapsedTime();
1900 }
1901 void end_strong_roots() {
1902 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1903 }
1904 double strong_roots_time() const { return _strong_roots_time; }
1905
1906 void start_term_time() {
1907 note_term_attempt();
1908 _start_term = os::elapsedTime();
1909 }
1910 void end_term_time() {
1911 _term_time += (os::elapsedTime() - _start_term);
1912 }
1913 double term_time() const { return _term_time; }
1914
1915 double elapsed_time() const {
1916 return os::elapsedTime() - _start;
1917 }
1918
1919 static void
1920 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1921 void
1922 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1923
1924 size_t* surviving_young_words() {
1925 // We add on to hide entry 0 which accumulates surviving words for
1926 // age -1 regions (i.e. non-young ones)
1927 return _surviving_young_words;
1928 }
1929
1930 void retire_alloc_buffers() {
1931 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1932 size_t waste = _alloc_buffers[ap]->words_remaining();
1933 add_to_alloc_buffer_waste(waste);
1934 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1935 true /* end_of_gc */,
1936 false /* retain */);
1937 }
1938 }
1939
1940 template <class T> void deal_with_reference(T* ref_to_scan) {
1941 if (has_partial_array_mask(ref_to_scan)) {
1942 _partial_scan_cl->do_oop_nv(ref_to_scan);
1943 } else {
1944 // Note: we can use "raw" versions of "region_containing" because
1945 // "obj_to_scan" is definitely in the heap, and is not in a
1946 // humongous region.
1947 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1948 _evac_cl->set_region(r);
1949 _evac_cl->do_oop_nv(ref_to_scan);
1950 }
1951 }
1952
1953 void deal_with_reference(StarTask ref) {
1954 assert(verify_task(ref), "sanity");
1955 if (ref.is_narrow()) {
1956 deal_with_reference((narrowOop*)ref);
1957 } else {
1958 deal_with_reference((oop*)ref);
1959 }
1960 }
1961
1962 public:
1963 void trim_queue();
1964 };
1965
1966 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP