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).
14 *
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/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
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
45
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class GenerationSpec;
49 class OopsInHeapRegionClosure;
50 class G1KlassScanClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
64
65 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
67
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
70
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
76
77 class YoungList : public CHeapObj<mtGC> {
78 private:
79 G1CollectedHeap* _g1h;
80
81 HeapRegion* _head;
82
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
85
86 HeapRegion* _curr;
87
88 uint _length;
89 uint _survivor_length;
90
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
93
94 void empty_list(HeapRegion* list);
95
96 public:
97 YoungList(G1CollectedHeap* g1h);
98
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
101
102 void empty_list();
103 bool is_empty() { return _length == 0; }
104 uint length() { return _length; }
105 uint survivor_length() { return _survivor_length; }
106
107 // Currently we do not keep track of the used byte sum for the
108 // young list and the survivors and it'd be quite a lot of work to
109 // do so. When we'll eventually replace the young list with
110 // instances of HeapRegionLinkedList we'll get that for free. So,
111 // we'll report the more accurate information then.
112 size_t eden_used_bytes() {
113 assert(length() >= survivor_length(), "invariant");
114 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return (size_t) survivor_length() * HeapRegion::GrainBytes;
118 }
119
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
123
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
128
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
132
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
138
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
142
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
148
149 class MutatorAllocRegion : public G1AllocRegion {
150 protected:
151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
153 public:
154 MutatorAllocRegion()
155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
156 };
157
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // refence processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 void do_object(oop p) { assert(false, "Do not call."); }
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
563 // Second-level mutator allocation attempt: take the Heap_lock and
564 // retry the allocation attempt, potentially scheduling a GC
565 // pause. This should only be used for non-humongous allocations.
566 HeapWord* attempt_allocation_slow(size_t word_size,
567 unsigned int* gc_count_before_ret);
568
569 // Takes the Heap_lock and attempts a humongous allocation. It can
570 // potentially schedule a GC pause.
571 HeapWord* attempt_allocation_humongous(size_t word_size,
572 unsigned int* gc_count_before_ret);
573
574 // Allocation attempt that should be called during safepoints (e.g.,
575 // at the end of a successful GC). expect_null_mutator_alloc_region
576 // specifies whether the mutator alloc region is expected to be NULL
577 // or not.
578 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
579 bool expect_null_mutator_alloc_region);
580
581 // It dirties the cards that cover the block so that so that the post
582 // write barrier never queues anything when updating objects on this
583 // block. It is assumed (and in fact we assert) that the block
584 // belongs to a young region.
585 inline void dirty_young_block(HeapWord* start, size_t word_size);
586
587 // Allocate blocks during garbage collection. Will ensure an
588 // allocation region, either by picking one or expanding the
589 // heap, and then allocate a block of the given size. The block
590 // may not be a humongous - it must fit into a single heap region.
591 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
592
593 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
594 HeapRegion* alloc_region,
595 bool par,
596 size_t word_size);
597
598 // Ensure that no further allocations can happen in "r", bearing in mind
599 // that parallel threads might be attempting allocations.
600 void par_allocate_remaining_space(HeapRegion* r);
601
602 // Allocation attempt during GC for a survivor object / PLAB.
603 inline HeapWord* survivor_attempt_allocation(size_t word_size);
604
605 // Allocation attempt during GC for an old object / PLAB.
606 inline HeapWord* old_attempt_allocation(size_t word_size);
607
608 // These methods are the "callbacks" from the G1AllocRegion class.
609
610 // For mutator alloc regions.
611 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
612 void retire_mutator_alloc_region(HeapRegion* alloc_region,
613 size_t allocated_bytes);
614
615 // For GC alloc regions.
616 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
617 GCAllocPurpose ap);
618 void retire_gc_alloc_region(HeapRegion* alloc_region,
619 size_t allocated_bytes, GCAllocPurpose ap);
620
621 // - if explicit_gc is true, the GC is for a System.gc() or a heap
622 // inspection request and should collect the entire heap
623 // - if clear_all_soft_refs is true, all soft references should be
624 // cleared during the GC
625 // - if explicit_gc is false, word_size describes the allocation that
626 // the GC should attempt (at least) to satisfy
627 // - it returns false if it is unable to do the collection due to the
628 // GC locker being active, true otherwise
629 bool do_collection(bool explicit_gc,
630 bool clear_all_soft_refs,
631 size_t word_size);
632
633 // Callback from VM_G1CollectFull operation.
634 // Perform a full collection.
635 virtual void do_full_collection(bool clear_all_soft_refs);
636
637 // Resize the heap if necessary after a full collection. If this is
638 // after a collect-for allocation, "word_size" is the allocation size,
639 // and will be considered part of the used portion of the heap.
640 void resize_if_necessary_after_full_collection(size_t word_size);
641
642 // Callback from VM_G1CollectForAllocation operation.
643 // This function does everything necessary/possible to satisfy a
644 // failed allocation request (including collection, expansion, etc.)
645 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
646
647 // Attempting to expand the heap sufficiently
648 // to support an allocation of the given "word_size". If
649 // successful, perform the allocation and return the address of the
650 // allocated block, or else "NULL".
651 HeapWord* expand_and_allocate(size_t word_size);
652
653 // Process any reference objects discovered during
654 // an incremental evacuation pause.
655 void process_discovered_references(uint no_of_gc_workers);
656
657 // Enqueue any remaining discovered references
658 // after processing.
659 void enqueue_discovered_references(uint no_of_gc_workers);
660
661 public:
662
663 G1MonitoringSupport* g1mm() {
664 assert(_g1mm != NULL, "should have been initialized");
665 return _g1mm;
666 }
667
668 // Expand the garbage-first heap by at least the given size (in bytes!).
669 // Returns true if the heap was expanded by the requested amount;
670 // false otherwise.
671 // (Rounds up to a HeapRegion boundary.)
672 bool expand(size_t expand_bytes);
673
674 // Do anything common to GC's.
675 virtual void gc_prologue(bool full);
676 virtual void gc_epilogue(bool full);
677
678 // We register a region with the fast "in collection set" test. We
679 // simply set to true the array slot corresponding to this region.
680 void register_region_with_in_cset_fast_test(HeapRegion* r) {
681 assert(_in_cset_fast_test_base != NULL, "sanity");
682 assert(r->in_collection_set(), "invariant");
683 uint index = r->hrs_index();
684 assert(index < _in_cset_fast_test_length, "invariant");
685 assert(!_in_cset_fast_test_base[index], "invariant");
686 _in_cset_fast_test_base[index] = true;
687 }
688
689 // This is a fast test on whether a reference points into the
690 // collection set or not. It does not assume that the reference
691 // points into the heap; if it doesn't, it will return false.
692 bool in_cset_fast_test(oop obj) {
693 assert(_in_cset_fast_test != NULL, "sanity");
694 if (_g1_committed.contains((HeapWord*) obj)) {
695 // no need to subtract the bottom of the heap from obj,
696 // _in_cset_fast_test is biased
697 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
698 bool ret = _in_cset_fast_test[index];
699 // let's make sure the result is consistent with what the slower
700 // test returns
701 assert( ret || !obj_in_cs(obj), "sanity");
702 assert(!ret || obj_in_cs(obj), "sanity");
703 return ret;
704 } else {
705 return false;
706 }
707 }
708
709 void clear_cset_fast_test() {
710 assert(_in_cset_fast_test_base != NULL, "sanity");
711 memset(_in_cset_fast_test_base, false,
712 (size_t) _in_cset_fast_test_length * sizeof(bool));
713 }
714
715 // This is called at the start of either a concurrent cycle or a Full
716 // GC to update the number of old marking cycles started.
717 void increment_old_marking_cycles_started();
718
719 // This is called at the end of either a concurrent cycle or a Full
720 // GC to update the number of old marking cycles completed. Those two
721 // can happen in a nested fashion, i.e., we start a concurrent
722 // cycle, a Full GC happens half-way through it which ends first,
723 // and then the cycle notices that a Full GC happened and ends
724 // too. The concurrent parameter is a boolean to help us do a bit
725 // tighter consistency checking in the method. If concurrent is
726 // false, the caller is the inner caller in the nesting (i.e., the
727 // Full GC). If concurrent is true, the caller is the outer caller
728 // in this nesting (i.e., the concurrent cycle). Further nesting is
729 // not currently supported. The end of this call also notifies
730 // the FullGCCount_lock in case a Java thread is waiting for a full
731 // GC to happen (e.g., it called System.gc() with
732 // +ExplicitGCInvokesConcurrent).
733 void increment_old_marking_cycles_completed(bool concurrent);
734
735 unsigned int old_marking_cycles_completed() {
736 return _old_marking_cycles_completed;
737 }
738
739 G1HRPrinter* hr_printer() { return &_hr_printer; }
740
741 protected:
742
743 // Shrink the garbage-first heap by at most the given size (in bytes!).
744 // (Rounds down to a HeapRegion boundary.)
745 virtual void shrink(size_t expand_bytes);
746 void shrink_helper(size_t expand_bytes);
747
748 #if TASKQUEUE_STATS
749 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
750 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
751 void reset_taskqueue_stats();
752 #endif // TASKQUEUE_STATS
753
754 // Schedule the VM operation that will do an evacuation pause to
755 // satisfy an allocation request of word_size. *succeeded will
756 // return whether the VM operation was successful (it did do an
757 // evacuation pause) or not (another thread beat us to it or the GC
758 // locker was active). Given that we should not be holding the
759 // Heap_lock when we enter this method, we will pass the
760 // gc_count_before (i.e., total_collections()) as a parameter since
761 // it has to be read while holding the Heap_lock. Currently, both
762 // methods that call do_collection_pause() release the Heap_lock
763 // before the call, so it's easy to read gc_count_before just before.
764 HeapWord* do_collection_pause(size_t word_size,
765 unsigned int gc_count_before,
766 bool* succeeded);
767
768 // The guts of the incremental collection pause, executed by the vm
769 // thread. It returns false if it is unable to do the collection due
770 // to the GC locker being active, true otherwise
771 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
772
773 // Actually do the work of evacuating the collection set.
774 void evacuate_collection_set();
775
776 // The g1 remembered set of the heap.
777 G1RemSet* _g1_rem_set;
778 // And it's mod ref barrier set, used to track updates for the above.
779 ModRefBarrierSet* _mr_bs;
780
781 // A set of cards that cover the objects for which the Rsets should be updated
782 // concurrently after the collection.
783 DirtyCardQueueSet _dirty_card_queue_set;
784
785 // The Heap Region Rem Set Iterator.
786 HeapRegionRemSetIterator** _rem_set_iterator;
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 OopClosure* non_root_closure);
828
829 // Frees a non-humongous region by initializing its contents and
830 // adding it to the free list that's passed as a parameter (this is
831 // usually a local list which will be appended to the master free
832 // list later). The used bytes of freed regions are accumulated in
833 // pre_used. If par is true, the region's RSet will not be freed
834 // up. The assumption is that this will be done later.
835 void free_region(HeapRegion* hr,
836 size_t* pre_used,
837 FreeRegionList* free_list,
838 bool par);
839
840 // Frees a humongous region by collapsing it into individual regions
841 // and calling free_region() for each of them. The freed regions
842 // will be added to the free list that's passed as a parameter (this
843 // is usually a local list which will be appended to the master free
844 // list later). The used bytes of freed regions are accumulated in
845 // pre_used. If par is true, the region's RSet will not be freed
846 // up. The assumption is that this will be done later.
847 void free_humongous_region(HeapRegion* hr,
848 size_t* pre_used,
849 FreeRegionList* free_list,
850 HumongousRegionSet* humongous_proxy_set,
851 bool par);
852
853 // Notifies all the necessary spaces that the committed space has
854 // been updated (either expanded or shrunk). It should be called
855 // after _g1_storage is updated.
856 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
857
858 // The concurrent marker (and the thread it runs in.)
859 ConcurrentMark* _cm;
860 ConcurrentMarkThread* _cmThread;
861 bool _mark_in_progress;
862
863 // The concurrent refiner.
864 ConcurrentG1Refine* _cg1r;
865
866 // The parallel task queues
867 RefToScanQueueSet *_task_queues;
868
869 // True iff a evacuation has failed in the current collection.
870 bool _evacuation_failed;
871
872 // Set the attribute indicating whether evacuation has failed in the
873 // current collection.
874 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
875
876 // Failed evacuations cause some logical from-space objects to have
877 // forwarding pointers to themselves. Reset them.
878 void remove_self_forwarding_pointers();
879
880 // When one is non-null, so is the other. Together, they each pair is
881 // an object with a preserved mark, and its mark value.
882 GrowableArray<oop>* _objs_with_preserved_marks;
883 GrowableArray<markOop>* _preserved_marks_of_objs;
884
885 // Preserve the mark of "obj", if necessary, in preparation for its mark
886 // word being overwritten with a self-forwarding-pointer.
887 void preserve_mark_if_necessary(oop obj, markOop m);
888
889 // The stack of evac-failure objects left to be scanned.
890 GrowableArray<oop>* _evac_failure_scan_stack;
891 // The closure to apply to evac-failure objects.
892
893 OopsInHeapRegionClosure* _evac_failure_closure;
894 // Set the field above.
895 void
896 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
897 _evac_failure_closure = evac_failure_closure;
898 }
899
900 // Push "obj" on the scan stack.
901 void push_on_evac_failure_scan_stack(oop obj);
902 // Process scan stack entries until the stack is empty.
903 void drain_evac_failure_scan_stack();
904 // True iff an invocation of "drain_scan_stack" is in progress; to
905 // prevent unnecessary recursion.
906 bool _drain_in_progress;
907
908 // Do any necessary initialization for evacuation-failure handling.
909 // "cl" is the closure that will be used to process evac-failure
910 // objects.
911 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
912 // Do any necessary cleanup for evacuation-failure handling data
913 // structures.
914 void finalize_for_evac_failure();
915
916 // An attempt to evacuate "obj" has failed; take necessary steps.
917 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
918 void handle_evacuation_failure_common(oop obj, markOop m);
919
920 #ifndef PRODUCT
921 // Support for forcing evacuation failures. Analogous to
922 // PromotionFailureALot for the other collectors.
923
924 // Records whether G1EvacuationFailureALot should be in effect
925 // for the current GC
926 bool _evacuation_failure_alot_for_current_gc;
927
928 // Used to record the GC number for interval checking when
929 // determining whether G1EvaucationFailureALot is in effect
930 // for the current GC.
931 size_t _evacuation_failure_alot_gc_number;
932
933 // Count of the number of evacuations between failures.
934 volatile size_t _evacuation_failure_alot_count;
935
936 // Set whether G1EvacuationFailureALot should be in effect
937 // for the current GC (based upon the type of GC and which
938 // command line flags are set);
939 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
940 bool during_initial_mark,
941 bool during_marking);
942
943 inline void set_evacuation_failure_alot_for_current_gc();
944
945 // Return true if it's time to cause an evacuation failure.
946 inline bool evacuation_should_fail();
947
948 // Reset the G1EvacuationFailureALot counters. Should be called at
949 // the end of an evacuation pause in which an evacuation failure ocurred.
950 inline void reset_evacuation_should_fail();
951 #endif // !PRODUCT
952
953 // ("Weak") Reference processing support.
954 //
955 // G1 has 2 instances of the referece processor class. One
956 // (_ref_processor_cm) handles reference object discovery
957 // and subsequent processing during concurrent marking cycles.
958 //
959 // The other (_ref_processor_stw) handles reference object
960 // discovery and processing during full GCs and incremental
961 // evacuation pauses.
962 //
963 // During an incremental pause, reference discovery will be
964 // temporarily disabled for _ref_processor_cm and will be
965 // enabled for _ref_processor_stw. At the end of the evacuation
966 // pause references discovered by _ref_processor_stw will be
967 // processed and discovery will be disabled. The previous
968 // setting for reference object discovery for _ref_processor_cm
969 // will be re-instated.
970 //
971 // At the start of marking:
972 // * Discovery by the CM ref processor is verified to be inactive
973 // and it's discovered lists are empty.
974 // * Discovery by the CM ref processor is then enabled.
975 //
976 // At the end of marking:
977 // * Any references on the CM ref processor's discovered
978 // lists are processed (possibly MT).
979 //
980 // At the start of full GC we:
981 // * Disable discovery by the CM ref processor and
982 // empty CM ref processor's discovered lists
983 // (without processing any entries).
984 // * Verify that the STW ref processor is inactive and it's
985 // discovered lists are empty.
986 // * Temporarily set STW ref processor discovery as single threaded.
987 // * Temporarily clear the STW ref processor's _is_alive_non_header
988 // field.
989 // * Finally enable discovery by the STW ref processor.
990 //
991 // The STW ref processor is used to record any discovered
992 // references during the full GC.
993 //
994 // At the end of a full GC we:
995 // * Enqueue any reference objects discovered by the STW ref processor
996 // that have non-live referents. This has the side-effect of
997 // making the STW ref processor inactive by disabling discovery.
998 // * Verify that the CM ref processor is still inactive
999 // and no references have been placed on it's discovered
1000 // lists (also checked as a precondition during initial marking).
1001
1002 // The (stw) reference processor...
1003 ReferenceProcessor* _ref_processor_stw;
1004
1005 // During reference object discovery, the _is_alive_non_header
1006 // closure (if non-null) is applied to the referent object to
1007 // determine whether the referent is live. If so then the
1008 // reference object does not need to be 'discovered' and can
1009 // be treated as a regular oop. This has the benefit of reducing
1010 // the number of 'discovered' reference objects that need to
1011 // be processed.
1012 //
1013 // Instance of the is_alive closure for embedding into the
1014 // STW reference processor as the _is_alive_non_header field.
1015 // Supplying a value for the _is_alive_non_header field is
1016 // optional but doing so prevents unnecessary additions to
1017 // the discovered lists during reference discovery.
1018 G1STWIsAliveClosure _is_alive_closure_stw;
1019
1020 // The (concurrent marking) reference processor...
1021 ReferenceProcessor* _ref_processor_cm;
1022
1023 // Instance of the concurrent mark is_alive closure for embedding
1024 // into the Concurrent Marking reference processor as the
1025 // _is_alive_non_header field. Supplying a value for the
1026 // _is_alive_non_header field is optional but doing so prevents
1027 // unnecessary additions to the discovered lists during reference
1028 // discovery.
1029 G1CMIsAliveClosure _is_alive_closure_cm;
1030
1031 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1032 HeapRegion** _worker_cset_start_region;
1033
1034 // Time stamp to validate the regions recorded in the cache
1035 // used by G1CollectedHeap::start_cset_region_for_worker().
1036 // The heap region entry for a given worker is valid iff
1037 // the associated time stamp value matches the current value
1038 // of G1CollectedHeap::_gc_time_stamp.
1039 unsigned int* _worker_cset_start_region_time_stamp;
1040
1041 enum G1H_process_strong_roots_tasks {
1042 G1H_PS_filter_satb_buffers,
1043 G1H_PS_refProcessor_oops_do,
1044 // Leave this one last.
1045 G1H_PS_NumElements
1046 };
1047
1048 SubTasksDone* _process_strong_tasks;
1049
1050 volatile bool _free_regions_coming;
1051
1052 public:
1053
1054 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1055
1056 void set_refine_cte_cl_concurrency(bool concurrent);
1057
1058 RefToScanQueue *task_queue(int i) const;
1059
1060 // A set of cards where updates happened during the GC
1061 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1062
1063 // A DirtyCardQueueSet that is used to hold cards that contain
1064 // references into the current collection set. This is used to
1065 // update the remembered sets of the regions in the collection
1066 // set in the event of an evacuation failure.
1067 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1068 { return _into_cset_dirty_card_queue_set; }
1069
1070 // Create a G1CollectedHeap with the specified policy.
1071 // Must call the initialize method afterwards.
1072 // May not return if something goes wrong.
1073 G1CollectedHeap(G1CollectorPolicy* policy);
1074
1075 // Initialize the G1CollectedHeap to have the initial and
1076 // maximum sizes and remembered and barrier sets
1077 // specified by the policy object.
1078 jint initialize();
1079
1080 // Initialize weak reference processing.
1081 virtual void ref_processing_init();
1082
1083 void set_par_threads(uint t) {
1084 SharedHeap::set_par_threads(t);
1085 // Done in SharedHeap but oddly there are
1086 // two _process_strong_tasks's in a G1CollectedHeap
1087 // so do it here too.
1088 _process_strong_tasks->set_n_threads(t);
1089 }
1090
1091 // Set _n_par_threads according to a policy TBD.
1092 void set_par_threads();
1093
1094 void set_n_termination(int t) {
1095 _process_strong_tasks->set_n_threads(t);
1096 }
1097
1098 virtual CollectedHeap::Name kind() const {
1099 return CollectedHeap::G1CollectedHeap;
1100 }
1101
1102 // The current policy object for the collector.
1103 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1104
1105 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1106
1107 // Adaptive size policy. No such thing for g1.
1108 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1109
1110 // The rem set and barrier set.
1111 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1112 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1113
1114 // The rem set iterator.
1115 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1116 return _rem_set_iterator[i];
1117 }
1118
1119 HeapRegionRemSetIterator* rem_set_iterator() {
1120 return _rem_set_iterator[0];
1121 }
1122
1123 unsigned get_gc_time_stamp() {
1124 return _gc_time_stamp;
1125 }
1126
1127 void reset_gc_time_stamp() {
1128 _gc_time_stamp = 0;
1129 OrderAccess::fence();
1130 // Clear the cached CSet starting regions and time stamps.
1131 // Their validity is dependent on the GC timestamp.
1132 clear_cset_start_regions();
1133 }
1134
1135 void check_gc_time_stamps() PRODUCT_RETURN;
1136
1137 void increment_gc_time_stamp() {
1138 ++_gc_time_stamp;
1139 OrderAccess::fence();
1140 }
1141
1142 // Reset the given region's GC timestamp. If it's starts humongous,
1143 // also reset the GC timestamp of its corresponding
1144 // continues humongous regions too.
1145 void reset_gc_time_stamps(HeapRegion* hr);
1146
1147 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1148 DirtyCardQueue* into_cset_dcq,
1149 bool concurrent, int worker_i);
1150
1151 // The shared block offset table array.
1152 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1153
1154 // Reference Processing accessors
1155
1156 // The STW reference processor....
1157 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1158
1159 // The Concurent Marking reference processor...
1160 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1161
1162 virtual size_t capacity() const;
1163 virtual size_t used() const;
1164 // This should be called when we're not holding the heap lock. The
1165 // result might be a bit inaccurate.
1166 size_t used_unlocked() const;
1167 size_t recalculate_used() const;
1168
1169 // These virtual functions do the actual allocation.
1170 // Some heaps may offer a contiguous region for shared non-blocking
1171 // allocation, via inlined code (by exporting the address of the top and
1172 // end fields defining the extent of the contiguous allocation region.)
1173 // But G1CollectedHeap doesn't yet support this.
1174
1175 // Return an estimate of the maximum allocation that could be performed
1176 // without triggering any collection or expansion activity. In a
1177 // generational collector, for example, this is probably the largest
1178 // allocation that could be supported (without expansion) in the youngest
1179 // generation. It is "unsafe" because no locks are taken; the result
1180 // should be treated as an approximation, not a guarantee, for use in
1181 // heuristic resizing decisions.
1182 virtual size_t unsafe_max_alloc();
1183
1184 virtual bool is_maximal_no_gc() const {
1185 return _g1_storage.uncommitted_size() == 0;
1186 }
1187
1188 // The total number of regions in the heap.
1189 uint n_regions() { return _hrs.length(); }
1190
1191 // The max number of regions in the heap.
1192 uint max_regions() { return _hrs.max_length(); }
1193
1194 // The number of regions that are completely free.
1195 uint free_regions() { return _free_list.length(); }
1196
1197 // The number of regions that are not completely free.
1198 uint used_regions() { return n_regions() - free_regions(); }
1199
1200 // The number of regions available for "regular" expansion.
1201 uint expansion_regions() { return _expansion_regions; }
1202
1203 // Factory method for HeapRegion instances. It will return NULL if
1204 // the allocation fails.
1205 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1206
1207 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1208 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1209 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1210 void verify_dirty_young_regions() PRODUCT_RETURN;
1211
1212 // verify_region_sets() performs verification over the region
1213 // lists. It will be compiled in the product code to be used when
1214 // necessary (i.e., during heap verification).
1215 void verify_region_sets();
1216
1217 // verify_region_sets_optional() is planted in the code for
1218 // list verification in non-product builds (and it can be enabled in
1219 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1220 #if HEAP_REGION_SET_FORCE_VERIFY
1221 void verify_region_sets_optional() {
1222 verify_region_sets();
1223 }
1224 #else // HEAP_REGION_SET_FORCE_VERIFY
1225 void verify_region_sets_optional() { }
1226 #endif // HEAP_REGION_SET_FORCE_VERIFY
1227
1228 #ifdef ASSERT
1229 bool is_on_master_free_list(HeapRegion* hr) {
1230 return hr->containing_set() == &_free_list;
1231 }
1232
1233 bool is_in_humongous_set(HeapRegion* hr) {
1234 return hr->containing_set() == &_humongous_set;
1235 }
1236 #endif // ASSERT
1237
1238 // Wrapper for the region list operations that can be called from
1239 // methods outside this class.
1240
1241 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1242 _secondary_free_list.add_as_tail(list);
1243 }
1244
1245 void append_secondary_free_list() {
1246 _free_list.add_as_head(&_secondary_free_list);
1247 }
1248
1249 void append_secondary_free_list_if_not_empty_with_lock() {
1250 // If the secondary free list looks empty there's no reason to
1251 // take the lock and then try to append it.
1252 if (!_secondary_free_list.is_empty()) {
1253 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1254 append_secondary_free_list();
1255 }
1256 }
1257
1258 void old_set_remove(HeapRegion* hr) {
1259 _old_set.remove(hr);
1260 }
1261
1262 size_t non_young_capacity_bytes() {
1263 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1264 }
1265
1266 void set_free_regions_coming();
1267 void reset_free_regions_coming();
1268 bool free_regions_coming() { return _free_regions_coming; }
1269 void wait_while_free_regions_coming();
1270
1271 // Determine whether the given region is one that we are using as an
1272 // old GC alloc region.
1273 bool is_old_gc_alloc_region(HeapRegion* hr) {
1274 return hr == _retained_old_gc_alloc_region;
1275 }
1276
1277 // Perform a collection of the heap; intended for use in implementing
1278 // "System.gc". This probably implies as full a collection as the
1279 // "CollectedHeap" supports.
1280 virtual void collect(GCCause::Cause cause);
1281
1282 // The same as above but assume that the caller holds the Heap_lock.
1283 void collect_locked(GCCause::Cause cause);
1284
1285 // True iff a evacuation has failed in the most-recent collection.
1286 bool evacuation_failed() { return _evacuation_failed; }
1287
1288 // It will free a region if it has allocated objects in it that are
1289 // all dead. It calls either free_region() or
1290 // free_humongous_region() depending on the type of the region that
1291 // is passed to it.
1292 void free_region_if_empty(HeapRegion* hr,
1293 size_t* pre_used,
1294 FreeRegionList* free_list,
1295 OldRegionSet* old_proxy_set,
1296 HumongousRegionSet* humongous_proxy_set,
1297 HRRSCleanupTask* hrrs_cleanup_task,
1298 bool par);
1299
1300 // It appends the free list to the master free list and updates the
1301 // master humongous list according to the contents of the proxy
1302 // list. It also adjusts the total used bytes according to pre_used
1303 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1304 void update_sets_after_freeing_regions(size_t pre_used,
1305 FreeRegionList* free_list,
1306 OldRegionSet* old_proxy_set,
1307 HumongousRegionSet* humongous_proxy_set,
1308 bool par);
1309
1310 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1311 virtual bool is_in(const void* p) const;
1312
1313 // Return "TRUE" iff the given object address is within the collection
1314 // set.
1315 inline bool obj_in_cs(oop obj);
1316
1317 // Return "TRUE" iff the given object address is in the reserved
1318 // region of g1.
1319 bool is_in_g1_reserved(const void* p) const {
1320 return _g1_reserved.contains(p);
1321 }
1322
1323 // Returns a MemRegion that corresponds to the space that has been
1324 // reserved for the heap
1325 MemRegion g1_reserved() {
1326 return _g1_reserved;
1327 }
1328
1329 // Returns a MemRegion that corresponds to the space that has been
1330 // committed in the heap
1331 MemRegion g1_committed() {
1332 return _g1_committed;
1333 }
1334
1335 virtual bool is_in_closed_subset(const void* p) const;
1336
1337 // This resets the card table to all zeros. It is used after
1338 // a collection pause which used the card table to claim cards.
1339 void cleanUpCardTable();
1340
1341 // Iteration functions.
1342
1343 // Iterate over all the ref-containing fields of all objects, calling
1344 // "cl.do_oop" on each.
1345 virtual void oop_iterate(ExtendedOopClosure* cl);
1346
1347 // Same as above, restricted to a memory region.
1348 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1349
1350 // Iterate over all objects, calling "cl.do_object" on each.
1351 virtual void object_iterate(ObjectClosure* cl);
1352
1353 virtual void safe_object_iterate(ObjectClosure* cl) {
1354 object_iterate(cl);
1355 }
1356
1357 // Iterate over all objects allocated since the last collection, calling
1358 // "cl.do_object" on each. The heap must have been initialized properly
1359 // to support this function, or else this call will fail.
1360 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1361
1362 // Iterate over all spaces in use in the heap, in ascending address order.
1363 virtual void space_iterate(SpaceClosure* cl);
1364
1365 // Iterate over heap regions, in address order, terminating the
1366 // iteration early if the "doHeapRegion" method returns "true".
1367 void heap_region_iterate(HeapRegionClosure* blk) const;
1368
1369 // Return the region with the given index. It assumes the index is valid.
1370 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1371
1372 // Divide the heap region sequence into "chunks" of some size (the number
1373 // of regions divided by the number of parallel threads times some
1374 // overpartition factor, currently 4). Assumes that this will be called
1375 // in parallel by ParallelGCThreads worker threads with discinct worker
1376 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1377 // calls will use the same "claim_value", and that that claim value is
1378 // different from the claim_value of any heap region before the start of
1379 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1380 // attempting to claim the first region in each chunk, and, if
1381 // successful, applying the closure to each region in the chunk (and
1382 // setting the claim value of the second and subsequent regions of the
1383 // chunk.) For now requires that "doHeapRegion" always returns "false",
1384 // i.e., that a closure never attempt to abort a traversal.
1385 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1386 uint worker,
1387 uint no_of_par_workers,
1388 jint claim_value);
1389
1390 // It resets all the region claim values to the default.
1391 void reset_heap_region_claim_values();
1392
1393 // Resets the claim values of regions in the current
1394 // collection set to the default.
1395 void reset_cset_heap_region_claim_values();
1396
1397 #ifdef ASSERT
1398 bool check_heap_region_claim_values(jint claim_value);
1399
1400 // Same as the routine above but only checks regions in the
1401 // current collection set.
1402 bool check_cset_heap_region_claim_values(jint claim_value);
1403 #endif // ASSERT
1404
1405 // Clear the cached cset start regions and (more importantly)
1406 // the time stamps. Called when we reset the GC time stamp.
1407 void clear_cset_start_regions();
1408
1409 // Given the id of a worker, obtain or calculate a suitable
1410 // starting region for iterating over the current collection set.
1411 HeapRegion* start_cset_region_for_worker(int worker_i);
1412
1413 // This is a convenience method that is used by the
1414 // HeapRegionIterator classes to calculate the starting region for
1415 // each worker so that they do not all start from the same region.
1416 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1417
1418 // Iterate over the regions (if any) in the current collection set.
1419 void collection_set_iterate(HeapRegionClosure* blk);
1420
1421 // As above but starting from region r
1422 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1423
1424 // Returns the first (lowest address) compactible space in the heap.
1425 virtual CompactibleSpace* first_compactible_space();
1426
1427 // A CollectedHeap will contain some number of spaces. This finds the
1428 // space containing a given address, or else returns NULL.
1429 virtual Space* space_containing(const void* addr) const;
1430
1431 // A G1CollectedHeap will contain some number of heap regions. This
1432 // finds the region containing a given address, or else returns NULL.
1433 template <class T>
1434 inline HeapRegion* heap_region_containing(const T addr) const;
1435
1436 // Like the above, but requires "addr" to be in the heap (to avoid a
1437 // null-check), and unlike the above, may return an continuing humongous
1438 // region.
1439 template <class T>
1440 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1441
1442 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1443 // each address in the (reserved) heap is a member of exactly
1444 // one block. The defining characteristic of a block is that it is
1445 // possible to find its size, and thus to progress forward to the next
1446 // block. (Blocks may be of different sizes.) Thus, blocks may
1447 // represent Java objects, or they might be free blocks in a
1448 // free-list-based heap (or subheap), as long as the two kinds are
1449 // distinguishable and the size of each is determinable.
1450
1451 // Returns the address of the start of the "block" that contains the
1452 // address "addr". We say "blocks" instead of "object" since some heaps
1453 // may not pack objects densely; a chunk may either be an object or a
1454 // non-object.
1455 virtual HeapWord* block_start(const void* addr) const;
1456
1457 // Requires "addr" to be the start of a chunk, and returns its size.
1458 // "addr + size" is required to be the start of a new chunk, or the end
1459 // of the active area of the heap.
1460 virtual size_t block_size(const HeapWord* addr) const;
1461
1462 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1463 // the block is an object.
1464 virtual bool block_is_obj(const HeapWord* addr) const;
1465
1466 // Does this heap support heap inspection? (+PrintClassHistogram)
1467 virtual bool supports_heap_inspection() const { return true; }
1468
1469 // Section on thread-local allocation buffers (TLABs)
1470 // See CollectedHeap for semantics.
1471
1472 virtual bool supports_tlab_allocation() const;
1473 virtual size_t tlab_capacity(Thread* thr) const;
1474 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1475
1476 // Can a compiler initialize a new object without store barriers?
1477 // This permission only extends from the creation of a new object
1478 // via a TLAB up to the first subsequent safepoint. If such permission
1479 // is granted for this heap type, the compiler promises to call
1480 // defer_store_barrier() below on any slow path allocation of
1481 // a new object for which such initializing store barriers will
1482 // have been elided. G1, like CMS, allows this, but should be
1483 // ready to provide a compensating write barrier as necessary
1484 // if that storage came out of a non-young region. The efficiency
1485 // of this implementation depends crucially on being able to
1486 // answer very efficiently in constant time whether a piece of
1487 // storage in the heap comes from a young region or not.
1488 // See ReduceInitialCardMarks.
1489 virtual bool can_elide_tlab_store_barriers() const {
1490 return true;
1491 }
1492
1493 virtual bool card_mark_must_follow_store() const {
1494 return true;
1495 }
1496
1497 bool is_in_young(const oop obj) {
1498 HeapRegion* hr = heap_region_containing(obj);
1499 return hr != NULL && hr->is_young();
1500 }
1501
1502 #ifdef ASSERT
1503 virtual bool is_in_partial_collection(const void* p);
1504 #endif
1505
1506 virtual bool is_scavengable(const void* addr);
1507
1508 // We don't need barriers for initializing stores to objects
1509 // in the young gen: for the SATB pre-barrier, there is no
1510 // pre-value that needs to be remembered; for the remembered-set
1511 // update logging post-barrier, we don't maintain remembered set
1512 // information for young gen objects.
1513 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1514 return is_in_young(new_obj);
1515 }
1516
1517 // Returns "true" iff the given word_size is "very large".
1518 static bool isHumongous(size_t word_size) {
1519 // Note this has to be strictly greater-than as the TLABs
1520 // are capped at the humongous thresold and we want to
1521 // ensure that we don't try to allocate a TLAB as
1522 // humongous and that we don't allocate a humongous
1523 // object in a TLAB.
1524 return word_size > _humongous_object_threshold_in_words;
1525 }
1526
1527 // Update mod union table with the set of dirty cards.
1528 void updateModUnion();
1529
1530 // Set the mod union bits corresponding to the given memRegion. Note
1531 // that this is always a safe operation, since it doesn't clear any
1532 // bits.
1533 void markModUnionRange(MemRegion mr);
1534
1535 // Records the fact that a marking phase is no longer in progress.
1536 void set_marking_complete() {
1537 _mark_in_progress = false;
1538 }
1539 void set_marking_started() {
1540 _mark_in_progress = true;
1541 }
1542 bool mark_in_progress() {
1543 return _mark_in_progress;
1544 }
1545
1546 // Print the maximum heap capacity.
1547 virtual size_t max_capacity() const;
1548
1549 virtual jlong millis_since_last_gc();
1550
1551 // Perform any cleanup actions necessary before allowing a verification.
1552 virtual void prepare_for_verify();
1553
1554 // Perform verification.
1555
1556 // vo == UsePrevMarking -> use "prev" marking information,
1557 // vo == UseNextMarking -> use "next" marking information
1558 // vo == UseMarkWord -> use the mark word in the object header
1559 //
1560 // NOTE: Only the "prev" marking information is guaranteed to be
1561 // consistent most of the time, so most calls to this should use
1562 // vo == UsePrevMarking.
1563 // Currently, there is only one case where this is called with
1564 // vo == UseNextMarking, which is to verify the "next" marking
1565 // information at the end of remark.
1566 // Currently there is only one place where this is called with
1567 // vo == UseMarkWord, which is to verify the marking during a
1568 // full GC.
1569 void verify(bool silent, VerifyOption vo);
1570
1571 // Override; it uses the "prev" marking information
1572 virtual void verify(bool silent);
1573 virtual void print_on(outputStream* st) const;
1574 virtual void print_extended_on(outputStream* st) const;
1575
1576 virtual void print_gc_threads_on(outputStream* st) const;
1577 virtual void gc_threads_do(ThreadClosure* tc) const;
1578
1579 // Override
1580 void print_tracing_info() const;
1581
1582 // The following two methods are helpful for debugging RSet issues.
1583 void print_cset_rsets() PRODUCT_RETURN;
1584 void print_all_rsets() PRODUCT_RETURN;
1585
1586 // Convenience function to be used in situations where the heap type can be
1587 // asserted to be this type.
1588 static G1CollectedHeap* heap();
1589
1590 void set_region_short_lived_locked(HeapRegion* hr);
1591 // add appropriate methods for any other surv rate groups
1592
1593 YoungList* young_list() { return _young_list; }
1594
1595 // debugging
1596 bool check_young_list_well_formed() {
1597 return _young_list->check_list_well_formed();
1598 }
1599
1600 bool check_young_list_empty(bool check_heap,
1601 bool check_sample = true);
1602
1603 // *** Stuff related to concurrent marking. It's not clear to me that so
1604 // many of these need to be public.
1605
1606 // The functions below are helper functions that a subclass of
1607 // "CollectedHeap" can use in the implementation of its virtual
1608 // functions.
1609 // This performs a concurrent marking of the live objects in a
1610 // bitmap off to the side.
1611 void doConcurrentMark();
1612
1613 bool isMarkedPrev(oop obj) const;
1614 bool isMarkedNext(oop obj) const;
1615
1616 // Determine if an object is dead, given the object and also
1617 // the region to which the object belongs. An object is dead
1618 // iff a) it was not allocated since the last mark and b) it
1619 // is not marked.
1620
1621 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1622 return
1623 !hr->obj_allocated_since_prev_marking(obj) &&
1624 !isMarkedPrev(obj);
1625 }
1626
1627 // This function returns true when an object has been
1628 // around since the previous marking and hasn't yet
1629 // been marked during this marking.
1630
1631 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1632 return
1633 !hr->obj_allocated_since_next_marking(obj) &&
1634 !isMarkedNext(obj);
1635 }
1636
1637 // Determine if an object is dead, given only the object itself.
1638 // This will find the region to which the object belongs and
1639 // then call the region version of the same function.
1640
1641 // Added if it is NULL it isn't dead.
1642
1643 bool is_obj_dead(const oop obj) const {
1644 const HeapRegion* hr = heap_region_containing(obj);
1645 if (hr == NULL) {
1646 if (obj == NULL) return false;
1647 else return true;
1648 }
1649 else return is_obj_dead(obj, hr);
1650 }
1651
1652 bool is_obj_ill(const oop obj) const {
1653 const HeapRegion* hr = heap_region_containing(obj);
1654 if (hr == NULL) {
1655 if (obj == NULL) return false;
1656 else return true;
1657 }
1658 else return is_obj_ill(obj, hr);
1659 }
1660
1661 // The methods below are here for convenience and dispatch the
1662 // appropriate method depending on value of the given VerifyOption
1663 // parameter. The options for that parameter are:
1664 //
1665 // vo == UsePrevMarking -> use "prev" marking information,
1666 // vo == UseNextMarking -> use "next" marking information,
1667 // vo == UseMarkWord -> use mark word from object header
1668
1669 bool is_obj_dead_cond(const oop obj,
1670 const HeapRegion* hr,
1671 const VerifyOption vo) const {
1672 switch (vo) {
1673 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1674 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1675 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1676 default: ShouldNotReachHere();
1677 }
1678 return false; // keep some compilers happy
1679 }
1680
1681 bool is_obj_dead_cond(const oop obj,
1682 const VerifyOption vo) const {
1683 switch (vo) {
1684 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1685 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1686 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1687 default: ShouldNotReachHere();
1688 }
1689 return false; // keep some compilers happy
1690 }
1691
1692 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1693 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1694 bool is_marked(oop obj, VerifyOption vo);
1695 const char* top_at_mark_start_str(VerifyOption vo);
1696
1697 // The following is just to alert the verification code
1698 // that a full collection has occurred and that the
1699 // remembered sets are no longer up to date.
1700 bool _full_collection;
1701 void set_full_collection() { _full_collection = true;}
1702 void clear_full_collection() {_full_collection = false;}
1703 bool full_collection() {return _full_collection;}
1704
1705 ConcurrentMark* concurrent_mark() const { return _cm; }
1706 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1707
1708 // The dirty cards region list is used to record a subset of regions
1709 // whose cards need clearing. The list if populated during the
1710 // remembered set scanning and drained during the card table
1711 // cleanup. Although the methods are reentrant, population/draining
1712 // phases must not overlap. For synchronization purposes the last
1713 // element on the list points to itself.
1714 HeapRegion* _dirty_cards_region_list;
1715 void push_dirty_cards_region(HeapRegion* hr);
1716 HeapRegion* pop_dirty_cards_region();
1717
1718 public:
1719 void stop_conc_gc_threads();
1720
1721 size_t pending_card_num();
1722 size_t cards_scanned();
1723
1724 protected:
1725 size_t _max_heap_capacity;
1726 };
1727
1728 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1729 private:
1730 bool _retired;
1731
1732 public:
1733 G1ParGCAllocBuffer(size_t gclab_word_size);
1734
1735 void set_buf(HeapWord* buf) {
1736 ParGCAllocBuffer::set_buf(buf);
1737 _retired = false;
1738 }
1739
1740 void retire(bool end_of_gc, bool retain) {
1741 if (_retired)
1742 return;
1743 ParGCAllocBuffer::retire(end_of_gc, retain);
1744 _retired = true;
1745 }
1746 };
1747
1748 class G1ParScanThreadState : public StackObj {
1749 protected:
1750 G1CollectedHeap* _g1h;
1751 RefToScanQueue* _refs;
1752 DirtyCardQueue _dcq;
1753 CardTableModRefBS* _ct_bs;
1754 G1RemSet* _g1_rem;
1755
1756 G1ParGCAllocBuffer _surviving_alloc_buffer;
1757 G1ParGCAllocBuffer _tenured_alloc_buffer;
1758 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1759 ageTable _age_table;
1760
1761 size_t _alloc_buffer_waste;
1762 size_t _undo_waste;
1763
1764 OopsInHeapRegionClosure* _evac_failure_cl;
1765 G1ParScanHeapEvacClosure* _evac_cl;
1766 G1ParScanPartialArrayClosure* _partial_scan_cl;
1767
1768 int _hash_seed;
1769 uint _queue_num;
1770
1771 size_t _term_attempts;
1772
1773 double _start;
1774 double _start_strong_roots;
1775 double _strong_roots_time;
1776 double _start_term;
1777 double _term_time;
1778
1779 // Map from young-age-index (0 == not young, 1 is youngest) to
1780 // surviving words. base is what we get back from the malloc call
1781 size_t* _surviving_young_words_base;
1782 // this points into the array, as we use the first few entries for padding
1783 size_t* _surviving_young_words;
1784
1785 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1786
1787 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1788
1789 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1790
1791 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1792 CardTableModRefBS* ctbs() { return _ct_bs; }
1793
1794 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1795 if (!from->is_survivor()) {
1796 _g1_rem->par_write_ref(from, p, tid);
1797 }
1798 }
1799
1800 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1801 // If the new value of the field points to the same region or
1802 // is the to-space, we don't need to include it in the Rset updates.
1803 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1804 size_t card_index = ctbs()->index_for(p);
1805 // If the card hasn't been added to the buffer, do it.
1806 if (ctbs()->mark_card_deferred(card_index)) {
1807 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1808 }
1809 }
1810 }
1811
1812 public:
1813 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1814
1815 ~G1ParScanThreadState() {
1816 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1817 }
1818
1819 RefToScanQueue* refs() { return _refs; }
1820 ageTable* age_table() { return &_age_table; }
1821
1822 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1823 return _alloc_buffers[purpose];
1824 }
1825
1826 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1827 size_t undo_waste() const { return _undo_waste; }
1828
1829 #ifdef ASSERT
1830 bool verify_ref(narrowOop* ref) const;
1831 bool verify_ref(oop* ref) const;
1832 bool verify_task(StarTask ref) const;
1833 #endif // ASSERT
1834
1835 template <class T> void push_on_queue(T* ref) {
1836 assert(verify_ref(ref), "sanity");
1837 refs()->push(ref);
1838 }
1839
1840 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1841 if (G1DeferredRSUpdate) {
1842 deferred_rs_update(from, p, tid);
1843 } else {
1844 immediate_rs_update(from, p, tid);
1845 }
1846 }
1847
1848 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1849 HeapWord* obj = NULL;
1850 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1851 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1852 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1853 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1854 alloc_buf->retire(false /* end_of_gc */, false /* retain */);
1855
1856 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1857 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1858 // Otherwise.
1859 alloc_buf->set_word_size(gclab_word_size);
1860 alloc_buf->set_buf(buf);
1861
1862 obj = alloc_buf->allocate(word_sz);
1863 assert(obj != NULL, "buffer was definitely big enough...");
1864 } else {
1865 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1866 }
1867 return obj;
1868 }
1869
1870 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1871 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1872 if (obj != NULL) return obj;
1873 return allocate_slow(purpose, word_sz);
1874 }
1875
1876 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1877 if (alloc_buffer(purpose)->contains(obj)) {
1878 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1879 "should contain whole object");
1880 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1881 } else {
1882 CollectedHeap::fill_with_object(obj, word_sz);
1883 add_to_undo_waste(word_sz);
1884 }
1885 }
1886
1887 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1888 _evac_failure_cl = evac_failure_cl;
1889 }
1890 OopsInHeapRegionClosure* evac_failure_closure() {
1891 return _evac_failure_cl;
1892 }
1893
1894 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1895 _evac_cl = evac_cl;
1896 }
1897
1898 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1899 _partial_scan_cl = partial_scan_cl;
1900 }
1901
1902 int* hash_seed() { return &_hash_seed; }
1903 uint queue_num() { return _queue_num; }
1904
1905 size_t term_attempts() const { return _term_attempts; }
1906 void note_term_attempt() { _term_attempts++; }
1907
1908 void start_strong_roots() {
1909 _start_strong_roots = os::elapsedTime();
1910 }
1911 void end_strong_roots() {
1912 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1913 }
1914 double strong_roots_time() const { return _strong_roots_time; }
1915
1916 void start_term_time() {
1917 note_term_attempt();
1918 _start_term = os::elapsedTime();
1919 }
1920 void end_term_time() {
1921 _term_time += (os::elapsedTime() - _start_term);
1922 }
1923 double term_time() const { return _term_time; }
1924
1925 double elapsed_time() const {
1926 return os::elapsedTime() - _start;
1927 }
1928
1929 static void
1930 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1931 void
1932 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1933
1934 size_t* surviving_young_words() {
1935 // We add on to hide entry 0 which accumulates surviving words for
1936 // age -1 regions (i.e. non-young ones)
1937 return _surviving_young_words;
1938 }
1939
1940 void retire_alloc_buffers() {
1941 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1942 size_t waste = _alloc_buffers[ap]->words_remaining();
1943 add_to_alloc_buffer_waste(waste);
1944 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1945 true /* end_of_gc */,
1946 false /* retain */);
1947 }
1948 }
1949
1950 template <class T> void deal_with_reference(T* ref_to_scan) {
1951 if (has_partial_array_mask(ref_to_scan)) {
1952 _partial_scan_cl->do_oop_nv(ref_to_scan);
1953 } else {
1954 // Note: we can use "raw" versions of "region_containing" because
1955 // "obj_to_scan" is definitely in the heap, and is not in a
1956 // humongous region.
1957 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1958 _evac_cl->set_region(r);
1959 _evac_cl->do_oop_nv(ref_to_scan);
1960 }
1961 }
1962
1963 void deal_with_reference(StarTask ref) {
1964 assert(verify_task(ref), "sanity");
1965 if (ref.is_narrow()) {
1966 deal_with_reference((narrowOop*)ref);
1967 } else {
1968 deal_with_reference((oop*)ref);
1969 }
1970 }
1971
1972 public:
1973 void trim_queue();
1974 };
1975
1976 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP