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
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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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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/g1MonitoringSupport.hpp"
32 #include "gc_implementation/g1/g1RemSet.hpp"
33 #include "gc_implementation/g1/g1YCTypes.hpp"
34 #include "gc_implementation/g1/heapRegionSeq.hpp"
35 #include "gc_implementation/g1/heapRegionSets.hpp"
36 #include "gc_implementation/shared/hSpaceCounters.hpp"
37 #include "gc_implementation/shared/gcTrace.hpp"
38 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
39 #include "memory/barrierSet.hpp"
40 #include "memory/memRegion.hpp"
41 #include "memory/sharedHeap.hpp"
42 #include "utilities/stack.hpp"
43
44 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
45 // It uses the "Garbage First" heap organization and algorithm, which
46 // may combine concurrent marking with parallel, incremental compaction of
47 // heap subsets that will yield large amounts of garbage.
48
49 class HeapRegion;
50 class HRRSCleanupTask;
51 class PermanentGenerationSpec;
52 class GenerationSpec;
53 class OopsInHeapRegionClosure;
54 class G1ScanHeapEvacClosure;
55 class ObjectClosure;
56 class SpaceClosure;
57 class CompactibleSpaceClosure;
58 class Space;
59 class G1CollectorPolicy;
60 class GenRemSet;
61 class G1RemSet;
62 class HeapRegionRemSetIterator;
63 class ConcurrentMark;
64 class ConcurrentMarkThread;
65 class ConcurrentG1Refine;
66 class ConcurrentGCTimer;
67 class GenerationCounters;
68 class STWGCTimer;
69 class G1NewTracer;
70 class G1OldTracer;
71
72 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
73 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
74
75 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
76 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
77
78 enum GCAllocPurpose {
79 GCAllocForTenured,
80 GCAllocForSurvived,
81 GCAllocPurposeCount
82 };
83
84 class YoungList : public CHeapObj<mtGC> {
85 private:
86 G1CollectedHeap* _g1h;
87
88 HeapRegion* _head;
89
90 HeapRegion* _survivor_head;
91 HeapRegion* _survivor_tail;
92
93 HeapRegion* _curr;
94
95 uint _length;
96 uint _survivor_length;
97
98 size_t _last_sampled_rs_lengths;
99 size_t _sampled_rs_lengths;
100
101 void empty_list(HeapRegion* list);
102
103 public:
104 YoungList(G1CollectedHeap* g1h);
105
106 void push_region(HeapRegion* hr);
107 void add_survivor_region(HeapRegion* hr);
108
109 void empty_list();
110 bool is_empty() { return _length == 0; }
111 uint length() { return _length; }
112 uint survivor_length() { return _survivor_length; }
113
114 // Currently we do not keep track of the used byte sum for the
115 // young list and the survivors and it'd be quite a lot of work to
116 // do so. When we'll eventually replace the young list with
117 // instances of HeapRegionLinkedList we'll get that for free. So,
118 // we'll report the more accurate information then.
119 size_t eden_used_bytes() {
120 assert(length() >= survivor_length(), "invariant");
121 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
122 }
123 size_t survivor_used_bytes() {
124 return (size_t) survivor_length() * HeapRegion::GrainBytes;
125 }
126
127 void rs_length_sampling_init();
128 bool rs_length_sampling_more();
129 void rs_length_sampling_next();
130
131 void reset_sampled_info() {
132 _last_sampled_rs_lengths = 0;
133 }
134 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
135
136 // for development purposes
137 void reset_auxilary_lists();
138 void clear() { _head = NULL; _length = 0; }
139
140 void clear_survivors() {
141 _survivor_head = NULL;
142 _survivor_tail = NULL;
143 _survivor_length = 0;
144 }
145
146 HeapRegion* first_region() { return _head; }
147 HeapRegion* first_survivor_region() { return _survivor_head; }
148 HeapRegion* last_survivor_region() { return _survivor_tail; }
149
150 // debugging
151 bool check_list_well_formed();
152 bool check_list_empty(bool check_sample = true);
153 void print();
154 };
155
156 class MutatorAllocRegion : public G1AllocRegion {
157 protected:
158 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
159 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
160 public:
161 MutatorAllocRegion()
162 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
163 };
164
165 // The G1 STW is alive closure.
166 // An instance is embedded into the G1CH and used as the
167 // (optional) _is_alive_non_header closure in the STW
168 // reference processor. It is also extensively used during
169 // refence processing during STW evacuation pauses.
170 class G1STWIsAliveClosure: public BoolObjectClosure {
171 G1CollectedHeap* _g1;
172 public:
173 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
174 void do_object(oop p) { assert(false, "Do not call."); }
175 bool do_object_b(oop p);
176 };
177
178 class SurvivorGCAllocRegion : public G1AllocRegion {
179 protected:
180 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
181 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
182 public:
183 SurvivorGCAllocRegion()
184 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
185 };
186
187 class OldGCAllocRegion : public G1AllocRegion {
188 protected:
189 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
190 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
191 public:
192 OldGCAllocRegion()
193 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
194 };
195
196 class RefineCardTableEntryClosure;
197
198 class G1CollectedHeap : public SharedHeap {
199 friend class VM_G1CollectForAllocation;
200 friend class VM_GenCollectForPermanentAllocation;
201 friend class VM_G1CollectFull;
202 friend class VM_G1IncCollectionPause;
203 friend class VMStructs;
204 friend class MutatorAllocRegion;
205 friend class SurvivorGCAllocRegion;
206 friend class OldGCAllocRegion;
207
208 // Closures used in implementation.
209 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
210 friend class G1ParCopyClosure;
211 friend class G1IsAliveClosure;
212 friend class G1EvacuateFollowersClosure;
213 friend class G1ParScanThreadState;
214 friend class G1ParScanClosureSuper;
215 friend class G1ParEvacuateFollowersClosure;
216 friend class G1ParTask;
217 friend class G1FreeGarbageRegionClosure;
218 friend class RefineCardTableEntryClosure;
219 friend class G1PrepareCompactClosure;
220 friend class RegionSorter;
221 friend class RegionResetter;
222 friend class CountRCClosure;
223 friend class EvacPopObjClosure;
224 friend class G1ParCleanupCTTask;
225
226 // Other related classes.
227 friend class G1MarkSweep;
228
229 private:
230 // The one and only G1CollectedHeap, so static functions can find it.
231 static G1CollectedHeap* _g1h;
232
233 static size_t _humongous_object_threshold_in_words;
234
235 // Storage for the G1 heap (excludes the permanent generation).
236 VirtualSpace _g1_storage;
237 MemRegion _g1_reserved;
238
239 // The part of _g1_storage that is currently committed.
240 MemRegion _g1_committed;
241
242 // The master free list. It will satisfy all new region allocations.
243 MasterFreeRegionList _free_list;
244
245 // The secondary free list which contains regions that have been
246 // freed up during the cleanup process. This will be appended to the
247 // master free list when appropriate.
248 SecondaryFreeRegionList _secondary_free_list;
249
250 // It keeps track of the old regions.
251 MasterOldRegionSet _old_set;
252
253 // It keeps track of the humongous regions.
254 MasterHumongousRegionSet _humongous_set;
255
256 // The number of regions we could create by expansion.
257 uint _expansion_regions;
258
259 // The block offset table for the G1 heap.
260 G1BlockOffsetSharedArray* _bot_shared;
261
262 // Tears down the region sets / lists so that they are empty and the
263 // regions on the heap do not belong to a region set / list. The
264 // only exception is the humongous set which we leave unaltered. If
265 // free_list_only is true, it will only tear down the master free
266 // list. It is called before a Full GC (free_list_only == false) or
267 // before heap shrinking (free_list_only == true).
268 void tear_down_region_sets(bool free_list_only);
269
270 // Rebuilds the region sets / lists so that they are repopulated to
271 // reflect the contents of the heap. The only exception is the
272 // humongous set which was not torn down in the first place. If
273 // free_list_only is true, it will only rebuild the master free
274 // list. It is called after a Full GC (free_list_only == false) or
275 // after heap shrinking (free_list_only == true).
276 void rebuild_region_sets(bool free_list_only);
277
278 // The sequence of all heap regions in the heap.
279 HeapRegionSeq _hrs;
280
281 // Alloc region used to satisfy mutator allocation requests.
282 MutatorAllocRegion _mutator_alloc_region;
283
284 // Alloc region used to satisfy allocation requests by the GC for
285 // survivor objects.
286 SurvivorGCAllocRegion _survivor_gc_alloc_region;
287
288 // PLAB sizing policy for survivors.
289 PLABStats _survivor_plab_stats;
290
291 // Alloc region used to satisfy allocation requests by the GC for
292 // old objects.
293 OldGCAllocRegion _old_gc_alloc_region;
294
295 // PLAB sizing policy for tenured objects.
296 PLABStats _old_plab_stats;
297
298 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
299 PLABStats* stats = NULL;
300
301 switch (purpose) {
302 case GCAllocForSurvived:
303 stats = &_survivor_plab_stats;
304 break;
305 case GCAllocForTenured:
306 stats = &_old_plab_stats;
307 break;
308 default:
309 assert(false, "unrecognized GCAllocPurpose");
310 }
311
312 return stats;
313 }
314
315 // The last old region we allocated to during the last GC.
316 // Typically, it is not full so we should re-use it during the next GC.
317 HeapRegion* _retained_old_gc_alloc_region;
318
319 // It specifies whether we should attempt to expand the heap after a
320 // region allocation failure. If heap expansion fails we set this to
321 // false so that we don't re-attempt the heap expansion (it's likely
322 // that subsequent expansion attempts will also fail if one fails).
323 // Currently, it is only consulted during GC and it's reset at the
324 // start of each GC.
325 bool _expand_heap_after_alloc_failure;
326
327 // It resets the mutator alloc region before new allocations can take place.
328 void init_mutator_alloc_region();
329
330 // It releases the mutator alloc region.
331 void release_mutator_alloc_region();
332
333 // It initializes the GC alloc regions at the start of a GC.
334 void init_gc_alloc_regions();
335
336 // It releases the GC alloc regions at the end of a GC.
337 void release_gc_alloc_regions(uint no_of_gc_workers);
338
339 // It does any cleanup that needs to be done on the GC alloc regions
340 // before a Full GC.
341 void abandon_gc_alloc_regions();
342
343 // Helper for monitoring and management support.
344 G1MonitoringSupport* _g1mm;
345
346 // Determines PLAB size for a particular allocation purpose.
347 size_t desired_plab_sz(GCAllocPurpose purpose);
348
349 // Outside of GC pauses, the number of bytes used in all regions other
350 // than the current allocation region.
351 size_t _summary_bytes_used;
352
353 // This is used for a quick test on whether a reference points into
354 // the collection set or not. Basically, we have an array, with one
355 // byte per region, and that byte denotes whether the corresponding
356 // region is in the collection set or not. The entry corresponding
357 // the bottom of the heap, i.e., region 0, is pointed to by
358 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
359 // biased so that it actually points to address 0 of the address
360 // space, to make the test as fast as possible (we can simply shift
361 // the address to address into it, instead of having to subtract the
362 // bottom of the heap from the address before shifting it; basically
363 // it works in the same way the card table works).
364 bool* _in_cset_fast_test;
365
366 // The allocated array used for the fast test on whether a reference
367 // points into the collection set or not. This field is also used to
368 // free the array.
369 bool* _in_cset_fast_test_base;
370
371 // The length of the _in_cset_fast_test_base array.
372 uint _in_cset_fast_test_length;
373
374 volatile unsigned _gc_time_stamp;
375
376 size_t* _surviving_young_words;
377
378 G1HRPrinter _hr_printer;
379
380 void setup_surviving_young_words();
381 void update_surviving_young_words(size_t* surv_young_words);
382 void cleanup_surviving_young_words();
383
384 // It decides whether an explicit GC should start a concurrent cycle
385 // instead of doing a STW GC. Currently, a concurrent cycle is
386 // explicitly started if:
387 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
388 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
389 // (c) cause == _g1_humongous_allocation
390 bool should_do_concurrent_full_gc(GCCause::Cause cause);
391
392 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
393 // concurrent cycles) we have started.
394 volatile unsigned int _old_marking_cycles_started;
395
396 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
397 // concurrent cycles) we have completed.
398 volatile unsigned int _old_marking_cycles_completed;
399
400 bool _concurrent_cycle_started;
401
402 // This is a non-product method that is helpful for testing. It is
403 // called at the end of a GC and artificially expands the heap by
404 // allocating a number of dead regions. This way we can induce very
405 // frequent marking cycles and stress the cleanup / concurrent
406 // cleanup code more (as all the regions that will be allocated by
407 // this method will be found dead by the marking cycle).
408 void allocate_dummy_regions() PRODUCT_RETURN;
409
410 // Clear RSets after a compaction. It also resets the GC time stamps.
411 void clear_rsets_post_compaction();
412
413 // If the HR printer is active, dump the state of the regions in the
414 // heap after a compaction.
415 void print_hrs_post_compaction();
416
417 double verify(bool guard, const char* msg);
418 void verify_before_gc();
419 void verify_after_gc();
420
421 void log_gc_header();
422 void log_gc_footer(double pause_time_sec);
423
424 // These are macros so that, if the assert fires, we get the correct
425 // line number, file, etc.
426
427 #define heap_locking_asserts_err_msg(_extra_message_) \
428 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
429 (_extra_message_), \
430 BOOL_TO_STR(Heap_lock->owned_by_self()), \
431 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
432 BOOL_TO_STR(Thread::current()->is_VM_thread()))
433
434 #define assert_heap_locked() \
435 do { \
436 assert(Heap_lock->owned_by_self(), \
437 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
438 } while (0)
439
440 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
441 do { \
442 assert(Heap_lock->owned_by_self() || \
443 (SafepointSynchronize::is_at_safepoint() && \
444 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
445 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
446 "should be at a safepoint")); \
447 } while (0)
448
449 #define assert_heap_locked_and_not_at_safepoint() \
450 do { \
451 assert(Heap_lock->owned_by_self() && \
452 !SafepointSynchronize::is_at_safepoint(), \
453 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
454 "should not be at a safepoint")); \
455 } while (0)
456
457 #define assert_heap_not_locked() \
458 do { \
459 assert(!Heap_lock->owned_by_self(), \
460 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
461 } while (0)
462
463 #define assert_heap_not_locked_and_not_at_safepoint() \
464 do { \
465 assert(!Heap_lock->owned_by_self() && \
466 !SafepointSynchronize::is_at_safepoint(), \
467 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
468 "should not be at a safepoint")); \
469 } while (0)
470
471 #define assert_at_safepoint(_should_be_vm_thread_) \
472 do { \
473 assert(SafepointSynchronize::is_at_safepoint() && \
474 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
475 heap_locking_asserts_err_msg("should be at a safepoint")); \
476 } while (0)
477
478 #define assert_not_at_safepoint() \
479 do { \
480 assert(!SafepointSynchronize::is_at_safepoint(), \
481 heap_locking_asserts_err_msg("should not be at a safepoint")); \
482 } while (0)
483
484 protected:
485
486 // The young region list.
487 YoungList* _young_list;
488
489 // The current policy object for the collector.
490 G1CollectorPolicy* _g1_policy;
491
492 // This is the second level of trying to allocate a new region. If
493 // new_region() didn't find a region on the free_list, this call will
494 // check whether there's anything available on the
495 // secondary_free_list and/or wait for more regions to appear on
496 // that list, if _free_regions_coming is set.
497 HeapRegion* new_region_try_secondary_free_list();
498
499 // Try to allocate a single non-humongous HeapRegion sufficient for
500 // an allocation of the given word_size. If do_expand is true,
501 // attempt to expand the heap if necessary to satisfy the allocation
502 // request.
503 HeapRegion* new_region(size_t word_size, bool do_expand);
504
505 // Attempt to satisfy a humongous allocation request of the given
506 // size by finding a contiguous set of free regions of num_regions
507 // length and remove them from the master free list. Return the
508 // index of the first region or G1_NULL_HRS_INDEX if the search
509 // was unsuccessful.
510 uint humongous_obj_allocate_find_first(uint num_regions,
511 size_t word_size);
512
513 // Initialize a contiguous set of free regions of length num_regions
514 // and starting at index first so that they appear as a single
515 // humongous region.
516 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
517 uint num_regions,
518 size_t word_size);
519
520 // Attempt to allocate a humongous object of the given size. Return
521 // NULL if unsuccessful.
522 HeapWord* humongous_obj_allocate(size_t word_size);
523
524 // The following two methods, allocate_new_tlab() and
525 // mem_allocate(), are the two main entry points from the runtime
526 // into the G1's allocation routines. They have the following
527 // assumptions:
528 //
529 // * They should both be called outside safepoints.
530 //
531 // * They should both be called without holding the Heap_lock.
532 //
533 // * All allocation requests for new TLABs should go to
534 // allocate_new_tlab().
535 //
536 // * All non-TLAB allocation requests should go to mem_allocate().
537 //
538 // * If either call cannot satisfy the allocation request using the
539 // current allocating region, they will try to get a new one. If
540 // this fails, they will attempt to do an evacuation pause and
541 // retry the allocation.
542 //
543 // * If all allocation attempts fail, even after trying to schedule
544 // an evacuation pause, allocate_new_tlab() will return NULL,
545 // whereas mem_allocate() will attempt a heap expansion and/or
546 // schedule a Full GC.
547 //
548 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
549 // should never be called with word_size being humongous. All
550 // humongous allocation requests should go to mem_allocate() which
551 // will satisfy them with a special path.
552
553 virtual HeapWord* allocate_new_tlab(size_t word_size);
554
555 virtual HeapWord* mem_allocate(size_t word_size,
556 bool* gc_overhead_limit_was_exceeded);
557
558 // The following three methods take a gc_count_before_ret
559 // parameter which is used to return the GC count if the method
560 // returns NULL. Given that we are required to read the GC count
561 // while holding the Heap_lock, and these paths will take the
562 // Heap_lock at some point, it's easier to get them to read the GC
563 // count while holding the Heap_lock before they return NULL instead
564 // of the caller (namely: mem_allocate()) having to also take the
565 // Heap_lock just to read the GC count.
566
567 // First-level mutator allocation attempt: try to allocate out of
568 // the mutator alloc region without taking the Heap_lock. This
569 // should only be used for non-humongous allocations.
570 inline HeapWord* attempt_allocation(size_t word_size,
571 unsigned int* gc_count_before_ret);
572
573 // Second-level mutator allocation attempt: take the Heap_lock and
574 // retry the allocation attempt, potentially scheduling a GC
575 // pause. This should only be used for non-humongous allocations.
576 HeapWord* attempt_allocation_slow(size_t word_size,
577 unsigned int* gc_count_before_ret);
578
579 // Takes the Heap_lock and attempts a humongous allocation. It can
580 // potentially schedule a GC pause.
581 HeapWord* attempt_allocation_humongous(size_t word_size,
582 unsigned int* gc_count_before_ret);
583
584 // Allocation attempt that should be called during safepoints (e.g.,
585 // at the end of a successful GC). expect_null_mutator_alloc_region
586 // specifies whether the mutator alloc region is expected to be NULL
587 // or not.
588 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
589 bool expect_null_mutator_alloc_region);
590
591 // It dirties the cards that cover the block so that so that the post
592 // write barrier never queues anything when updating objects on this
593 // block. It is assumed (and in fact we assert) that the block
594 // belongs to a young region.
595 inline void dirty_young_block(HeapWord* start, size_t word_size);
596
597 // Allocate blocks during garbage collection. Will ensure an
598 // allocation region, either by picking one or expanding the
599 // heap, and then allocate a block of the given size. The block
600 // may not be a humongous - it must fit into a single heap region.
601 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
602
603 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
604 HeapRegion* alloc_region,
605 bool par,
606 size_t word_size);
607
608 // Ensure that no further allocations can happen in "r", bearing in mind
609 // that parallel threads might be attempting allocations.
610 void par_allocate_remaining_space(HeapRegion* r);
611
612 // Allocation attempt during GC for a survivor object / PLAB.
613 inline HeapWord* survivor_attempt_allocation(size_t word_size);
614
615 // Allocation attempt during GC for an old object / PLAB.
616 inline HeapWord* old_attempt_allocation(size_t word_size);
617
618 // These methods are the "callbacks" from the G1AllocRegion class.
619
620 // For mutator alloc regions.
621 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
622 void retire_mutator_alloc_region(HeapRegion* alloc_region,
623 size_t allocated_bytes);
624
625 // For GC alloc regions.
626 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
627 GCAllocPurpose ap);
628 void retire_gc_alloc_region(HeapRegion* alloc_region,
629 size_t allocated_bytes, GCAllocPurpose ap);
630
631 // - if explicit_gc is true, the GC is for a System.gc() or a heap
632 // inspection request and should collect the entire heap
633 // - if clear_all_soft_refs is true, all soft references should be
634 // cleared during the GC
635 // - if explicit_gc is false, word_size describes the allocation that
636 // the GC should attempt (at least) to satisfy
637 // - it returns false if it is unable to do the collection due to the
638 // GC locker being active, true otherwise
639 bool do_collection(bool explicit_gc,
640 bool clear_all_soft_refs,
641 size_t word_size);
642
643 // Callback from VM_G1CollectFull operation.
644 // Perform a full collection.
645 void do_full_collection(bool clear_all_soft_refs);
646
647 // Resize the heap if necessary after a full collection. If this is
648 // after a collect-for allocation, "word_size" is the allocation size,
649 // and will be considered part of the used portion of the heap.
650 void resize_if_necessary_after_full_collection(size_t word_size);
651
652 // Callback from VM_G1CollectForAllocation operation.
653 // This function does everything necessary/possible to satisfy a
654 // failed allocation request (including collection, expansion, etc.)
655 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
656
657 // Attempting to expand the heap sufficiently
658 // to support an allocation of the given "word_size". If
659 // successful, perform the allocation and return the address of the
660 // allocated block, or else "NULL".
661 HeapWord* expand_and_allocate(size_t word_size);
662
663 // Process any reference objects discovered during
664 // an incremental evacuation pause.
665 void process_discovered_references(uint no_of_gc_workers);
666
667 // Enqueue any remaining discovered references
668 // after processing.
669 void enqueue_discovered_references(uint no_of_gc_workers);
670
671 public:
672
673 G1MonitoringSupport* g1mm() {
674 assert(_g1mm != NULL, "should have been initialized");
675 return _g1mm;
676 }
677
678 // Expand the garbage-first heap by at least the given size (in bytes!).
679 // Returns true if the heap was expanded by the requested amount;
680 // false otherwise.
681 // (Rounds up to a HeapRegion boundary.)
682 bool expand(size_t expand_bytes);
683
684 // Do anything common to GC's.
685 virtual void gc_prologue(bool full);
686 virtual void gc_epilogue(bool full);
687
688 // We register a region with the fast "in collection set" test. We
689 // simply set to true the array slot corresponding to this region.
690 void register_region_with_in_cset_fast_test(HeapRegion* r) {
691 assert(_in_cset_fast_test_base != NULL, "sanity");
692 assert(r->in_collection_set(), "invariant");
693 uint index = r->hrs_index();
694 assert(index < _in_cset_fast_test_length, "invariant");
695 assert(!_in_cset_fast_test_base[index], "invariant");
696 _in_cset_fast_test_base[index] = true;
697 }
698
699 // This is a fast test on whether a reference points into the
700 // collection set or not. It does not assume that the reference
701 // points into the heap; if it doesn't, it will return false.
702 bool in_cset_fast_test(oop obj) {
703 assert(_in_cset_fast_test != NULL, "sanity");
704 if (_g1_committed.contains((HeapWord*) obj)) {
705 // no need to subtract the bottom of the heap from obj,
706 // _in_cset_fast_test is biased
707 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
708 bool ret = _in_cset_fast_test[index];
709 // let's make sure the result is consistent with what the slower
710 // test returns
711 assert( ret || !obj_in_cs(obj), "sanity");
712 assert(!ret || obj_in_cs(obj), "sanity");
713 return ret;
714 } else {
715 return false;
716 }
717 }
718
719 void clear_cset_fast_test() {
720 assert(_in_cset_fast_test_base != NULL, "sanity");
721 memset(_in_cset_fast_test_base, false,
722 (size_t) _in_cset_fast_test_length * sizeof(bool));
723 }
724
725 // This is called at the start of either a concurrent cycle or a Full
726 // GC to update the number of old marking cycles started.
727 void increment_old_marking_cycles_started();
728
729 // This is called at the end of either a concurrent cycle or a Full
730 // GC to update the number of old marking cycles completed. Those two
731 // can happen in a nested fashion, i.e., we start a concurrent
732 // cycle, a Full GC happens half-way through it which ends first,
733 // and then the cycle notices that a Full GC happened and ends
734 // too. The concurrent parameter is a boolean to help us do a bit
735 // tighter consistency checking in the method. If concurrent is
736 // false, the caller is the inner caller in the nesting (i.e., the
737 // Full GC). If concurrent is true, the caller is the outer caller
738 // in this nesting (i.e., the concurrent cycle). Further nesting is
739 // not currently supported. The end of this call also notifies
740 // the FullGCCount_lock in case a Java thread is waiting for a full
741 // GC to happen (e.g., it called System.gc() with
742 // +ExplicitGCInvokesConcurrent).
743 void increment_old_marking_cycles_completed(bool concurrent);
744
745 unsigned int old_marking_cycles_completed() {
746 return _old_marking_cycles_completed;
747 }
748
749 void register_concurrent_cycle_start(jlong start_time);
750 void register_concurrent_cycle_end();
751 void trace_heap_after_concurrent_cycle();
752
753 G1YCType yc_type();
754
755 G1HRPrinter* hr_printer() { return &_hr_printer; }
756
757 protected:
758
759 // Shrink the garbage-first heap by at most the given size (in bytes!).
760 // (Rounds down to a HeapRegion boundary.)
761 virtual void shrink(size_t expand_bytes);
762 void shrink_helper(size_t expand_bytes);
763
764 #if TASKQUEUE_STATS
765 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
766 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
767 void reset_taskqueue_stats();
768 #endif // TASKQUEUE_STATS
769
770 // Schedule the VM operation that will do an evacuation pause to
771 // satisfy an allocation request of word_size. *succeeded will
772 // return whether the VM operation was successful (it did do an
773 // evacuation pause) or not (another thread beat us to it or the GC
774 // locker was active). Given that we should not be holding the
775 // Heap_lock when we enter this method, we will pass the
776 // gc_count_before (i.e., total_collections()) as a parameter since
777 // it has to be read while holding the Heap_lock. Currently, both
778 // methods that call do_collection_pause() release the Heap_lock
779 // before the call, so it's easy to read gc_count_before just before.
780 HeapWord* do_collection_pause(size_t word_size,
781 unsigned int gc_count_before,
782 bool* succeeded);
783
784 // The guts of the incremental collection pause, executed by the vm
785 // thread. It returns false if it is unable to do the collection due
786 // to the GC locker being active, true otherwise
787 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
788
789 // Actually do the work of evacuating the collection set.
790 void evacuate_collection_set();
791
792 // The g1 remembered set of the heap.
793 G1RemSet* _g1_rem_set;
794 // And it's mod ref barrier set, used to track updates for the above.
795 ModRefBarrierSet* _mr_bs;
796
797 // A set of cards that cover the objects for which the Rsets should be updated
798 // concurrently after the collection.
799 DirtyCardQueueSet _dirty_card_queue_set;
800
801 // The Heap Region Rem Set Iterator.
802 HeapRegionRemSetIterator** _rem_set_iterator;
803
804 // The closure used to refine a single card.
805 RefineCardTableEntryClosure* _refine_cte_cl;
806
807 // A function to check the consistency of dirty card logs.
808 void check_ct_logs_at_safepoint();
809
810 // A DirtyCardQueueSet that is used to hold cards that contain
811 // references into the current collection set. This is used to
812 // update the remembered sets of the regions in the collection
813 // set in the event of an evacuation failure.
814 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
815
816 // After a collection pause, make the regions in the CS into free
817 // regions.
818 void free_collection_set(HeapRegion* cs_head);
819
820 // Abandon the current collection set without recording policy
821 // statistics or updating free lists.
822 void abandon_collection_set(HeapRegion* cs_head);
823
824 // Applies "scan_non_heap_roots" to roots outside the heap,
825 // "scan_rs" to roots inside the heap (having done "set_region" to
826 // indicate the region in which the root resides), and does "scan_perm"
827 // (setting the generation to the perm generation.) If "scan_rs" is
828 // NULL, then this step is skipped. The "worker_i"
829 // param is for use with parallel roots processing, and should be
830 // the "i" of the calling parallel worker thread's work(i) function.
831 // In the sequential case this param will be ignored.
832 void g1_process_strong_roots(bool collecting_perm_gen,
833 ScanningOption so,
834 OopClosure* scan_non_heap_roots,
835 OopsInHeapRegionClosure* scan_rs,
836 OopsInGenClosure* scan_perm,
837 int worker_i);
838
839 // Apply "blk" to all the weak roots of the system. These include
840 // JNI weak roots, the code cache, system dictionary, symbol table,
841 // string table, and referents of reachable weak refs.
842 void g1_process_weak_roots(OopClosure* root_closure,
843 OopClosure* non_root_closure);
844
845 // Frees a non-humongous region by initializing its contents and
846 // adding it to the free list that's passed as a parameter (this is
847 // usually a local list which will be appended to the master free
848 // list later). The used bytes of freed regions are accumulated in
849 // pre_used. If par is true, the region's RSet will not be freed
850 // up. The assumption is that this will be done later.
851 void free_region(HeapRegion* hr,
852 size_t* pre_used,
853 FreeRegionList* free_list,
854 bool par);
855
856 // Frees a humongous region by collapsing it into individual regions
857 // and calling free_region() for each of them. The freed regions
858 // will be added to the free list that's passed as a parameter (this
859 // is usually a local list which will be appended to the master free
860 // list later). The used bytes of freed regions are accumulated in
861 // pre_used. If par is true, the region's RSet will not be freed
862 // up. The assumption is that this will be done later.
863 void free_humongous_region(HeapRegion* hr,
864 size_t* pre_used,
865 FreeRegionList* free_list,
866 HumongousRegionSet* humongous_proxy_set,
867 bool par);
868
869 // Notifies all the necessary spaces that the committed space has
870 // been updated (either expanded or shrunk). It should be called
871 // after _g1_storage is updated.
872 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
873
874 // The concurrent marker (and the thread it runs in.)
875 ConcurrentMark* _cm;
876 ConcurrentMarkThread* _cmThread;
877 bool _mark_in_progress;
878
879 // The concurrent refiner.
880 ConcurrentG1Refine* _cg1r;
881
882 // The parallel task queues
883 RefToScanQueueSet *_task_queues;
884
885 // True iff a evacuation has failed in the current collection.
886 bool _evacuation_failed;
887
888 // Set the attribute indicating whether evacuation has failed in the
889 // current collection.
890 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
891
892 // Failed evacuations cause some logical from-space objects to have
893 // forwarding pointers to themselves. Reset them.
894 void remove_self_forwarding_pointers();
895
896 // Together, these store an object with a preserved mark, and its mark value.
897 Stack<oop, mtGC> _objs_with_preserved_marks;
898 Stack<markOop, mtGC> _preserved_marks_of_objs;
899
900 // Preserve the mark of "obj", if necessary, in preparation for its mark
901 // word being overwritten with a self-forwarding-pointer.
902 void preserve_mark_if_necessary(oop obj, markOop m);
903
904 // The stack of evac-failure objects left to be scanned.
905 GrowableArray<oop>* _evac_failure_scan_stack;
906 // The closure to apply to evac-failure objects.
907
908 OopsInHeapRegionClosure* _evac_failure_closure;
909 // Set the field above.
910 void
911 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
912 _evac_failure_closure = evac_failure_closure;
913 }
914
915 // Push "obj" on the scan stack.
916 void push_on_evac_failure_scan_stack(oop obj);
917 // Process scan stack entries until the stack is empty.
918 void drain_evac_failure_scan_stack();
919 // True iff an invocation of "drain_scan_stack" is in progress; to
920 // prevent unnecessary recursion.
921 bool _drain_in_progress;
922
923 // Do any necessary initialization for evacuation-failure handling.
924 // "cl" is the closure that will be used to process evac-failure
925 // objects.
926 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
927 // Do any necessary cleanup for evacuation-failure handling data
928 // structures.
929 void finalize_for_evac_failure();
930
931 // An attempt to evacuate "obj" has failed; take necessary steps.
932 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
933 void handle_evacuation_failure_common(oop obj, markOop m);
934
935 #ifndef PRODUCT
936 // Support for forcing evacuation failures. Analogous to
937 // PromotionFailureALot for the other collectors.
938
939 // Records whether G1EvacuationFailureALot should be in effect
940 // for the current GC
941 bool _evacuation_failure_alot_for_current_gc;
942
943 // Used to record the GC number for interval checking when
944 // determining whether G1EvaucationFailureALot is in effect
945 // for the current GC.
946 size_t _evacuation_failure_alot_gc_number;
947
948 // Count of the number of evacuations between failures.
949 volatile size_t _evacuation_failure_alot_count;
950
951 // Set whether G1EvacuationFailureALot should be in effect
952 // for the current GC (based upon the type of GC and which
953 // command line flags are set);
954 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
955 bool during_initial_mark,
956 bool during_marking);
957
958 inline void set_evacuation_failure_alot_for_current_gc();
959
960 // Return true if it's time to cause an evacuation failure.
961 inline bool evacuation_should_fail();
962
963 // Reset the G1EvacuationFailureALot counters. Should be called at
964 // the end of an evacuation pause in which an evacuation failure ocurred.
965 inline void reset_evacuation_should_fail();
966 #endif // !PRODUCT
967
968 // ("Weak") Reference processing support.
969 //
970 // G1 has 2 instances of the referece processor class. One
971 // (_ref_processor_cm) handles reference object discovery
972 // and subsequent processing during concurrent marking cycles.
973 //
974 // The other (_ref_processor_stw) handles reference object
975 // discovery and processing during full GCs and incremental
976 // evacuation pauses.
977 //
978 // During an incremental pause, reference discovery will be
979 // temporarily disabled for _ref_processor_cm and will be
980 // enabled for _ref_processor_stw. At the end of the evacuation
981 // pause references discovered by _ref_processor_stw will be
982 // processed and discovery will be disabled. The previous
983 // setting for reference object discovery for _ref_processor_cm
984 // will be re-instated.
985 //
986 // At the start of marking:
987 // * Discovery by the CM ref processor is verified to be inactive
988 // and it's discovered lists are empty.
989 // * Discovery by the CM ref processor is then enabled.
990 //
991 // At the end of marking:
992 // * Any references on the CM ref processor's discovered
993 // lists are processed (possibly MT).
994 //
995 // At the start of full GC we:
996 // * Disable discovery by the CM ref processor and
997 // empty CM ref processor's discovered lists
998 // (without processing any entries).
999 // * Verify that the STW ref processor is inactive and it's
1000 // discovered lists are empty.
1001 // * Temporarily set STW ref processor discovery as single threaded.
1002 // * Temporarily clear the STW ref processor's _is_alive_non_header
1003 // field.
1004 // * Finally enable discovery by the STW ref processor.
1005 //
1006 // The STW ref processor is used to record any discovered
1007 // references during the full GC.
1008 //
1009 // At the end of a full GC we:
1010 // * Enqueue any reference objects discovered by the STW ref processor
1011 // that have non-live referents. This has the side-effect of
1012 // making the STW ref processor inactive by disabling discovery.
1013 // * Verify that the CM ref processor is still inactive
1014 // and no references have been placed on it's discovered
1015 // lists (also checked as a precondition during initial marking).
1016
1017 // The (stw) reference processor...
1018 ReferenceProcessor* _ref_processor_stw;
1019
1020 STWGCTimer* _gc_timer_stw;
1021 ConcurrentGCTimer* _gc_timer_cm;
1022
1023 G1OldTracer* _gc_tracer_cm;
1024 G1NewTracer* _gc_tracer_stw;
1025
1026 // During reference object discovery, the _is_alive_non_header
1027 // closure (if non-null) is applied to the referent object to
1028 // determine whether the referent is live. If so then the
1029 // reference object does not need to be 'discovered' and can
1030 // be treated as a regular oop. This has the benefit of reducing
1031 // the number of 'discovered' reference objects that need to
1032 // be processed.
1033 //
1034 // Instance of the is_alive closure for embedding into the
1035 // STW reference processor as the _is_alive_non_header field.
1036 // Supplying a value for the _is_alive_non_header field is
1037 // optional but doing so prevents unnecessary additions to
1038 // the discovered lists during reference discovery.
1039 G1STWIsAliveClosure _is_alive_closure_stw;
1040
1041 // The (concurrent marking) reference processor...
1042 ReferenceProcessor* _ref_processor_cm;
1043
1044 // Instance of the concurrent mark is_alive closure for embedding
1045 // into the Concurrent Marking reference processor as the
1046 // _is_alive_non_header field. Supplying a value for the
1047 // _is_alive_non_header field is optional but doing so prevents
1048 // unnecessary additions to the discovered lists during reference
1049 // discovery.
1050 G1CMIsAliveClosure _is_alive_closure_cm;
1051
1052 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1053 HeapRegion** _worker_cset_start_region;
1054
1055 // Time stamp to validate the regions recorded in the cache
1056 // used by G1CollectedHeap::start_cset_region_for_worker().
1057 // The heap region entry for a given worker is valid iff
1058 // the associated time stamp value matches the current value
1059 // of G1CollectedHeap::_gc_time_stamp.
1060 unsigned int* _worker_cset_start_region_time_stamp;
1061
1062 enum G1H_process_strong_roots_tasks {
1063 G1H_PS_filter_satb_buffers,
1064 G1H_PS_refProcessor_oops_do,
1065 // Leave this one last.
1066 G1H_PS_NumElements
1067 };
1068
1069 SubTasksDone* _process_strong_tasks;
1070
1071 volatile bool _free_regions_coming;
1072
1073 public:
1074
1075 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1076
1077 void set_refine_cte_cl_concurrency(bool concurrent);
1078
1079 RefToScanQueue *task_queue(int i) const;
1080
1081 // A set of cards where updates happened during the GC
1082 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1083
1084 // A DirtyCardQueueSet that is used to hold cards that contain
1085 // references into the current collection set. This is used to
1086 // update the remembered sets of the regions in the collection
1087 // set in the event of an evacuation failure.
1088 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1089 { return _into_cset_dirty_card_queue_set; }
1090
1091 // Create a G1CollectedHeap with the specified policy.
1092 // Must call the initialize method afterwards.
1093 // May not return if something goes wrong.
1094 G1CollectedHeap(G1CollectorPolicy* policy);
1095
1096 // Initialize the G1CollectedHeap to have the initial and
1097 // maximum sizes, permanent generation, and remembered and barrier sets
1098 // specified by the policy object.
1099 jint initialize();
1100
1101 // Initialize weak reference processing.
1102 virtual void ref_processing_init();
1103
1104 void set_par_threads(uint t) {
1105 SharedHeap::set_par_threads(t);
1106 // Done in SharedHeap but oddly there are
1107 // two _process_strong_tasks's in a G1CollectedHeap
1108 // so do it here too.
1109 _process_strong_tasks->set_n_threads(t);
1110 }
1111
1112 // Set _n_par_threads according to a policy TBD.
1113 void set_par_threads();
1114
1115 void set_n_termination(int t) {
1116 _process_strong_tasks->set_n_threads(t);
1117 }
1118
1119 virtual CollectedHeap::Name kind() const {
1120 return CollectedHeap::G1CollectedHeap;
1121 }
1122
1123 // The current policy object for the collector.
1124 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1125
1126 // Adaptive size policy. No such thing for g1.
1127 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1128
1129 // The rem set and barrier set.
1130 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1131 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1132
1133 // The rem set iterator.
1134 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1135 return _rem_set_iterator[i];
1136 }
1137
1138 HeapRegionRemSetIterator* rem_set_iterator() {
1139 return _rem_set_iterator[0];
1140 }
1141
1142 unsigned get_gc_time_stamp() {
1143 return _gc_time_stamp;
1144 }
1145
1146 void reset_gc_time_stamp() {
1147 _gc_time_stamp = 0;
1148 OrderAccess::fence();
1149 // Clear the cached CSet starting regions and time stamps.
1150 // Their validity is dependent on the GC timestamp.
1151 clear_cset_start_regions();
1152 }
1153
1154 void check_gc_time_stamps() PRODUCT_RETURN;
1155
1156 void increment_gc_time_stamp() {
1157 ++_gc_time_stamp;
1158 OrderAccess::fence();
1159 }
1160
1161 // Reset the given region's GC timestamp. If it's starts humongous,
1162 // also reset the GC timestamp of its corresponding
1163 // continues humongous regions too.
1164 void reset_gc_time_stamps(HeapRegion* hr);
1165
1166 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1167 DirtyCardQueue* into_cset_dcq,
1168 bool concurrent, int worker_i);
1169
1170 // The shared block offset table array.
1171 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1172
1173 // Reference Processing accessors
1174
1175 // The STW reference processor....
1176 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1177
1178 // The Concurent Marking reference processor...
1179 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1180
1181 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1182 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1183
1184 virtual size_t capacity() const;
1185 virtual size_t used() const;
1186 // This should be called when we're not holding the heap lock. The
1187 // result might be a bit inaccurate.
1188 size_t used_unlocked() const;
1189 size_t recalculate_used() const;
1190
1191 // These virtual functions do the actual allocation.
1192 // Some heaps may offer a contiguous region for shared non-blocking
1193 // allocation, via inlined code (by exporting the address of the top and
1194 // end fields defining the extent of the contiguous allocation region.)
1195 // But G1CollectedHeap doesn't yet support this.
1196
1197 // Return an estimate of the maximum allocation that could be performed
1198 // without triggering any collection or expansion activity. In a
1199 // generational collector, for example, this is probably the largest
1200 // allocation that could be supported (without expansion) in the youngest
1201 // generation. It is "unsafe" because no locks are taken; the result
1202 // should be treated as an approximation, not a guarantee, for use in
1203 // heuristic resizing decisions.
1204 virtual size_t unsafe_max_alloc();
1205
1206 virtual bool is_maximal_no_gc() const {
1207 return _g1_storage.uncommitted_size() == 0;
1208 }
1209
1210 // The total number of regions in the heap.
1211 uint n_regions() { return _hrs.length(); }
1212
1213 // The max number of regions in the heap.
1214 uint max_regions() { return _hrs.max_length(); }
1215
1216 // The number of regions that are completely free.
1217 uint free_regions() { return _free_list.length(); }
1218
1219 // The number of regions that are not completely free.
1220 uint used_regions() { return n_regions() - free_regions(); }
1221
1222 // The number of regions available for "regular" expansion.
1223 uint expansion_regions() { return _expansion_regions; }
1224
1225 // Factory method for HeapRegion instances. It will return NULL if
1226 // the allocation fails.
1227 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1228
1229 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1230 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1231 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1232 void verify_dirty_young_regions() PRODUCT_RETURN;
1233
1234 // verify_region_sets() performs verification over the region
1235 // lists. It will be compiled in the product code to be used when
1236 // necessary (i.e., during heap verification).
1237 void verify_region_sets();
1238
1239 // verify_region_sets_optional() is planted in the code for
1240 // list verification in non-product builds (and it can be enabled in
1241 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1242 #if HEAP_REGION_SET_FORCE_VERIFY
1243 void verify_region_sets_optional() {
1244 verify_region_sets();
1245 }
1246 #else // HEAP_REGION_SET_FORCE_VERIFY
1247 void verify_region_sets_optional() { }
1248 #endif // HEAP_REGION_SET_FORCE_VERIFY
1249
1250 #ifdef ASSERT
1251 bool is_on_master_free_list(HeapRegion* hr) {
1252 return hr->containing_set() == &_free_list;
1253 }
1254
1255 bool is_in_humongous_set(HeapRegion* hr) {
1256 return hr->containing_set() == &_humongous_set;
1257 }
1258 #endif // ASSERT
1259
1260 // Wrapper for the region list operations that can be called from
1261 // methods outside this class.
1262
1263 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1264 _secondary_free_list.add_as_tail(list);
1265 }
1266
1267 void append_secondary_free_list() {
1268 _free_list.add_as_head(&_secondary_free_list);
1269 }
1270
1271 void append_secondary_free_list_if_not_empty_with_lock() {
1272 // If the secondary free list looks empty there's no reason to
1273 // take the lock and then try to append it.
1274 if (!_secondary_free_list.is_empty()) {
1275 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1276 append_secondary_free_list();
1277 }
1278 }
1279
1280 void old_set_remove(HeapRegion* hr) {
1281 _old_set.remove(hr);
1282 }
1283
1284 size_t non_young_capacity_bytes() {
1285 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1286 }
1287
1288 void set_free_regions_coming();
1289 void reset_free_regions_coming();
1290 bool free_regions_coming() { return _free_regions_coming; }
1291 void wait_while_free_regions_coming();
1292
1293 // Determine whether the given region is one that we are using as an
1294 // old GC alloc region.
1295 bool is_old_gc_alloc_region(HeapRegion* hr) {
1296 return hr == _retained_old_gc_alloc_region;
1297 }
1298
1299 // Perform a collection of the heap; intended for use in implementing
1300 // "System.gc". This probably implies as full a collection as the
1301 // "CollectedHeap" supports.
1302 virtual void collect(GCCause::Cause cause);
1303
1304 // The same as above but assume that the caller holds the Heap_lock.
1305 void collect_locked(GCCause::Cause cause);
1306
1307 // This interface assumes that it's being called by the
1308 // vm thread. It collects the heap assuming that the
1309 // heap lock is already held and that we are executing in
1310 // the context of the vm thread.
1311 virtual void collect_as_vm_thread(GCCause::Cause cause);
1312
1313 // True iff a evacuation has failed in the most-recent collection.
1314 bool evacuation_failed() { return _evacuation_failed; }
1315
1316 // It will free a region if it has allocated objects in it that are
1317 // all dead. It calls either free_region() or
1318 // free_humongous_region() depending on the type of the region that
1319 // is passed to it.
1320 void free_region_if_empty(HeapRegion* hr,
1321 size_t* pre_used,
1322 FreeRegionList* free_list,
1323 OldRegionSet* old_proxy_set,
1324 HumongousRegionSet* humongous_proxy_set,
1325 HRRSCleanupTask* hrrs_cleanup_task,
1326 bool par);
1327
1328 // It appends the free list to the master free list and updates the
1329 // master humongous list according to the contents of the proxy
1330 // list. It also adjusts the total used bytes according to pre_used
1331 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1332 void update_sets_after_freeing_regions(size_t pre_used,
1333 FreeRegionList* free_list,
1334 OldRegionSet* old_proxy_set,
1335 HumongousRegionSet* humongous_proxy_set,
1336 bool par);
1337
1338 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1339 virtual bool is_in(const void* p) const;
1340
1341 // Return "TRUE" iff the given object address is within the collection
1342 // set.
1343 inline bool obj_in_cs(oop obj);
1344
1345 // Return "TRUE" iff the given object address is in the reserved
1346 // region of g1 (excluding the permanent generation).
1347 bool is_in_g1_reserved(const void* p) const {
1348 return _g1_reserved.contains(p);
1349 }
1350
1351 // Returns a MemRegion that corresponds to the space that has been
1352 // reserved for the heap
1353 MemRegion g1_reserved() {
1354 return _g1_reserved;
1355 }
1356
1357 // Returns a MemRegion that corresponds to the space that has been
1358 // committed in the heap
1359 MemRegion g1_committed() {
1360 return _g1_committed;
1361 }
1362
1363 virtual bool is_in_closed_subset(const void* p) const;
1364
1365 // This resets the card table to all zeros. It is used after
1366 // a collection pause which used the card table to claim cards.
1367 void cleanUpCardTable();
1368
1369 // Iteration functions.
1370
1371 // Iterate over all the ref-containing fields of all objects, calling
1372 // "cl.do_oop" on each.
1373 virtual void oop_iterate(OopClosure* cl) {
1374 oop_iterate(cl, true);
1375 }
1376 void oop_iterate(OopClosure* cl, bool do_perm);
1377
1378 // Same as above, restricted to a memory region.
1379 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1380 oop_iterate(mr, cl, true);
1381 }
1382 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1383
1384 // Iterate over all objects, calling "cl.do_object" on each.
1385 virtual void object_iterate(ObjectClosure* cl) {
1386 object_iterate(cl, true);
1387 }
1388 virtual void safe_object_iterate(ObjectClosure* cl) {
1389 object_iterate(cl, true);
1390 }
1391 void object_iterate(ObjectClosure* cl, bool do_perm);
1392
1393 // Iterate over all objects allocated since the last collection, calling
1394 // "cl.do_object" on each. The heap must have been initialized properly
1395 // to support this function, or else this call will fail.
1396 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1397
1398 // Iterate over all spaces in use in the heap, in ascending address order.
1399 virtual void space_iterate(SpaceClosure* cl);
1400
1401 // Iterate over heap regions, in address order, terminating the
1402 // iteration early if the "doHeapRegion" method returns "true".
1403 void heap_region_iterate(HeapRegionClosure* blk) const;
1404
1405 // Return the region with the given index. It assumes the index is valid.
1406 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1407
1408 // Divide the heap region sequence into "chunks" of some size (the number
1409 // of regions divided by the number of parallel threads times some
1410 // overpartition factor, currently 4). Assumes that this will be called
1411 // in parallel by ParallelGCThreads worker threads with discinct worker
1412 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1413 // calls will use the same "claim_value", and that that claim value is
1414 // different from the claim_value of any heap region before the start of
1415 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1416 // attempting to claim the first region in each chunk, and, if
1417 // successful, applying the closure to each region in the chunk (and
1418 // setting the claim value of the second and subsequent regions of the
1419 // chunk.) For now requires that "doHeapRegion" always returns "false",
1420 // i.e., that a closure never attempt to abort a traversal.
1421 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1422 uint worker,
1423 uint no_of_par_workers,
1424 jint claim_value);
1425
1426 // It resets all the region claim values to the default.
1427 void reset_heap_region_claim_values();
1428
1429 // Resets the claim values of regions in the current
1430 // collection set to the default.
1431 void reset_cset_heap_region_claim_values();
1432
1433 #ifdef ASSERT
1434 bool check_heap_region_claim_values(jint claim_value);
1435
1436 // Same as the routine above but only checks regions in the
1437 // current collection set.
1438 bool check_cset_heap_region_claim_values(jint claim_value);
1439 #endif // ASSERT
1440
1441 // Clear the cached cset start regions and (more importantly)
1442 // the time stamps. Called when we reset the GC time stamp.
1443 void clear_cset_start_regions();
1444
1445 // Given the id of a worker, obtain or calculate a suitable
1446 // starting region for iterating over the current collection set.
1447 HeapRegion* start_cset_region_for_worker(int worker_i);
1448
1449 // This is a convenience method that is used by the
1450 // HeapRegionIterator classes to calculate the starting region for
1451 // each worker so that they do not all start from the same region.
1452 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1453
1454 // Iterate over the regions (if any) in the current collection set.
1455 void collection_set_iterate(HeapRegionClosure* blk);
1456
1457 // As above but starting from region r
1458 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1459
1460 // Returns the first (lowest address) compactible space in the heap.
1461 virtual CompactibleSpace* first_compactible_space();
1462
1463 // A CollectedHeap will contain some number of spaces. This finds the
1464 // space containing a given address, or else returns NULL.
1465 virtual Space* space_containing(const void* addr) const;
1466
1467 // A G1CollectedHeap will contain some number of heap regions. This
1468 // finds the region containing a given address, or else returns NULL.
1469 template <class T>
1470 inline HeapRegion* heap_region_containing(const T addr) const;
1471
1472 // Like the above, but requires "addr" to be in the heap (to avoid a
1473 // null-check), and unlike the above, may return an continuing humongous
1474 // region.
1475 template <class T>
1476 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1477
1478 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1479 // each address in the (reserved) heap is a member of exactly
1480 // one block. The defining characteristic of a block is that it is
1481 // possible to find its size, and thus to progress forward to the next
1482 // block. (Blocks may be of different sizes.) Thus, blocks may
1483 // represent Java objects, or they might be free blocks in a
1484 // free-list-based heap (or subheap), as long as the two kinds are
1485 // distinguishable and the size of each is determinable.
1486
1487 // Returns the address of the start of the "block" that contains the
1488 // address "addr". We say "blocks" instead of "object" since some heaps
1489 // may not pack objects densely; a chunk may either be an object or a
1490 // non-object.
1491 virtual HeapWord* block_start(const void* addr) const;
1492
1493 // Requires "addr" to be the start of a chunk, and returns its size.
1494 // "addr + size" is required to be the start of a new chunk, or the end
1495 // of the active area of the heap.
1496 virtual size_t block_size(const HeapWord* addr) const;
1497
1498 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1499 // the block is an object.
1500 virtual bool block_is_obj(const HeapWord* addr) const;
1501
1502 // Does this heap support heap inspection? (+PrintClassHistogram)
1503 virtual bool supports_heap_inspection() const { return true; }
1504
1505 // Section on thread-local allocation buffers (TLABs)
1506 // See CollectedHeap for semantics.
1507
1508 virtual bool supports_tlab_allocation() const;
1509 virtual size_t tlab_capacity(Thread* thr) const;
1510 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1511
1512 // Can a compiler initialize a new object without store barriers?
1513 // This permission only extends from the creation of a new object
1514 // via a TLAB up to the first subsequent safepoint. If such permission
1515 // is granted for this heap type, the compiler promises to call
1516 // defer_store_barrier() below on any slow path allocation of
1517 // a new object for which such initializing store barriers will
1518 // have been elided. G1, like CMS, allows this, but should be
1519 // ready to provide a compensating write barrier as necessary
1520 // if that storage came out of a non-young region. The efficiency
1521 // of this implementation depends crucially on being able to
1522 // answer very efficiently in constant time whether a piece of
1523 // storage in the heap comes from a young region or not.
1524 // See ReduceInitialCardMarks.
1525 virtual bool can_elide_tlab_store_barriers() const {
1526 return true;
1527 }
1528
1529 virtual bool card_mark_must_follow_store() const {
1530 return true;
1531 }
1532
1533 bool is_in_young(const oop obj) {
1534 HeapRegion* hr = heap_region_containing(obj);
1535 return hr != NULL && hr->is_young();
1536 }
1537
1538 #ifdef ASSERT
1539 virtual bool is_in_partial_collection(const void* p);
1540 #endif
1541
1542 virtual bool is_scavengable(const void* addr);
1543
1544 // We don't need barriers for initializing stores to objects
1545 // in the young gen: for the SATB pre-barrier, there is no
1546 // pre-value that needs to be remembered; for the remembered-set
1547 // update logging post-barrier, we don't maintain remembered set
1548 // information for young gen objects.
1549 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1550 return is_in_young(new_obj);
1551 }
1552
1553 // Can a compiler elide a store barrier when it writes
1554 // a permanent oop into the heap? Applies when the compiler
1555 // is storing x to the heap, where x->is_perm() is true.
1556 virtual bool can_elide_permanent_oop_store_barriers() const {
1557 // At least until perm gen collection is also G1-ified, at
1558 // which point this should return false.
1559 return true;
1560 }
1561
1562 // Returns "true" iff the given word_size is "very large".
1563 static bool isHumongous(size_t word_size) {
1564 // Note this has to be strictly greater-than as the TLABs
1565 // are capped at the humongous thresold and we want to
1566 // ensure that we don't try to allocate a TLAB as
1567 // humongous and that we don't allocate a humongous
1568 // object in a TLAB.
1569 return word_size > _humongous_object_threshold_in_words;
1570 }
1571
1572 // Update mod union table with the set of dirty cards.
1573 void updateModUnion();
1574
1575 // Set the mod union bits corresponding to the given memRegion. Note
1576 // that this is always a safe operation, since it doesn't clear any
1577 // bits.
1578 void markModUnionRange(MemRegion mr);
1579
1580 // Records the fact that a marking phase is no longer in progress.
1581 void set_marking_complete() {
1582 _mark_in_progress = false;
1583 }
1584 void set_marking_started() {
1585 _mark_in_progress = true;
1586 }
1587 bool mark_in_progress() {
1588 return _mark_in_progress;
1589 }
1590
1591 // Print the maximum heap capacity.
1592 virtual size_t max_capacity() const;
1593
1594 virtual jlong millis_since_last_gc();
1595
1596 // Perform any cleanup actions necessary before allowing a verification.
1597 virtual void prepare_for_verify();
1598
1599 // Perform verification.
1600
1601 // vo == UsePrevMarking -> use "prev" marking information,
1602 // vo == UseNextMarking -> use "next" marking information
1603 // vo == UseMarkWord -> use the mark word in the object header
1604 //
1605 // NOTE: Only the "prev" marking information is guaranteed to be
1606 // consistent most of the time, so most calls to this should use
1607 // vo == UsePrevMarking.
1608 // Currently, there is only one case where this is called with
1609 // vo == UseNextMarking, which is to verify the "next" marking
1610 // information at the end of remark.
1611 // Currently there is only one place where this is called with
1612 // vo == UseMarkWord, which is to verify the marking during a
1613 // full GC.
1614 void verify(bool silent, VerifyOption vo);
1615
1616 // Override; it uses the "prev" marking information
1617 virtual void verify(bool silent);
1618
1619 virtual void print_on(outputStream* st) const;
1620 virtual void print_extended_on(outputStream* st) const;
1621
1622 virtual void print_gc_threads_on(outputStream* st) const;
1623 virtual void gc_threads_do(ThreadClosure* tc) const;
1624
1625 // Override
1626 void print_tracing_info() const;
1627
1628 // The following two methods are helpful for debugging RSet issues.
1629 void print_cset_rsets() PRODUCT_RETURN;
1630 void print_all_rsets() PRODUCT_RETURN;
1631
1632 // Convenience function to be used in situations where the heap type can be
1633 // asserted to be this type.
1634 static G1CollectedHeap* heap();
1635
1636 void set_region_short_lived_locked(HeapRegion* hr);
1637 // add appropriate methods for any other surv rate groups
1638
1639 YoungList* young_list() { return _young_list; }
1640
1641 // debugging
1642 bool check_young_list_well_formed() {
1643 return _young_list->check_list_well_formed();
1644 }
1645
1646 bool check_young_list_empty(bool check_heap,
1647 bool check_sample = true);
1648
1649 // *** Stuff related to concurrent marking. It's not clear to me that so
1650 // many of these need to be public.
1651
1652 // The functions below are helper functions that a subclass of
1653 // "CollectedHeap" can use in the implementation of its virtual
1654 // functions.
1655 // This performs a concurrent marking of the live objects in a
1656 // bitmap off to the side.
1657 void doConcurrentMark();
1658
1659 bool isMarkedPrev(oop obj) const;
1660 bool isMarkedNext(oop obj) const;
1661
1662 // Determine if an object is dead, given the object and also
1663 // the region to which the object belongs. An object is dead
1664 // iff a) it was not allocated since the last mark and b) it
1665 // is not marked.
1666
1667 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1668 return
1669 !hr->obj_allocated_since_prev_marking(obj) &&
1670 !isMarkedPrev(obj);
1671 }
1672
1673 // This function returns true when an object has been
1674 // around since the previous marking and hasn't yet
1675 // been marked during this marking.
1676
1677 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1678 return
1679 !hr->obj_allocated_since_next_marking(obj) &&
1680 !isMarkedNext(obj);
1681 }
1682
1683 // Determine if an object is dead, given only the object itself.
1684 // This will find the region to which the object belongs and
1685 // then call the region version of the same function.
1686
1687 // Added if it is in permanent gen it isn't dead.
1688 // Added if it is NULL it isn't dead.
1689
1690 bool is_obj_dead(const oop obj) const {
1691 const HeapRegion* hr = heap_region_containing(obj);
1692 if (hr == NULL) {
1693 if (Universe::heap()->is_in_permanent(obj))
1694 return false;
1695 else if (obj == NULL) return false;
1696 else return true;
1697 }
1698 else return is_obj_dead(obj, hr);
1699 }
1700
1701 bool is_obj_ill(const oop obj) const {
1702 const HeapRegion* hr = heap_region_containing(obj);
1703 if (hr == NULL) {
1704 if (Universe::heap()->is_in_permanent(obj))
1705 return false;
1706 else if (obj == NULL) return false;
1707 else return true;
1708 }
1709 else return is_obj_ill(obj, hr);
1710 }
1711
1712 // The methods below are here for convenience and dispatch the
1713 // appropriate method depending on value of the given VerifyOption
1714 // parameter. The options for that parameter are:
1715 //
1716 // vo == UsePrevMarking -> use "prev" marking information,
1717 // vo == UseNextMarking -> use "next" marking information,
1718 // vo == UseMarkWord -> use mark word from object header
1719
1720 bool is_obj_dead_cond(const oop obj,
1721 const HeapRegion* hr,
1722 const VerifyOption vo) const {
1723 switch (vo) {
1724 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1725 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1726 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1727 default: ShouldNotReachHere();
1728 }
1729 return false; // keep some compilers happy
1730 }
1731
1732 bool is_obj_dead_cond(const oop obj,
1733 const VerifyOption vo) const {
1734 switch (vo) {
1735 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1736 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1737 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1738 default: ShouldNotReachHere();
1739 }
1740 return false; // keep some compilers happy
1741 }
1742
1743 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1744 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1745 bool is_marked(oop obj, VerifyOption vo);
1746 const char* top_at_mark_start_str(VerifyOption vo);
1747
1748 // The following is just to alert the verification code
1749 // that a full collection has occurred and that the
1750 // remembered sets are no longer up to date.
1751 bool _full_collection;
1752 void set_full_collection() { _full_collection = true;}
1753 void clear_full_collection() {_full_collection = false;}
1754 bool full_collection() {return _full_collection;}
1755
1756 ConcurrentMark* concurrent_mark() const { return _cm; }
1757 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1758
1759 // The dirty cards region list is used to record a subset of regions
1760 // whose cards need clearing. The list if populated during the
1761 // remembered set scanning and drained during the card table
1762 // cleanup. Although the methods are reentrant, population/draining
1763 // phases must not overlap. For synchronization purposes the last
1764 // element on the list points to itself.
1765 HeapRegion* _dirty_cards_region_list;
1766 void push_dirty_cards_region(HeapRegion* hr);
1767 HeapRegion* pop_dirty_cards_region();
1768
1769 public:
1770 void stop_conc_gc_threads();
1771
1772 size_t pending_card_num();
1773 size_t cards_scanned();
1774
1775 protected:
1776 size_t _max_heap_capacity;
1777 };
1778
1779 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1780 private:
1781 bool _retired;
1782
1783 public:
1784 G1ParGCAllocBuffer(size_t gclab_word_size);
1785
1786 void set_buf(HeapWord* buf) {
1787 ParGCAllocBuffer::set_buf(buf);
1788 _retired = false;
1789 }
1790
1791 void retire(bool end_of_gc, bool retain) {
1792 if (_retired)
1793 return;
1794 ParGCAllocBuffer::retire(end_of_gc, retain);
1795 _retired = true;
1796 }
1797 };
1798
1799 class G1ParScanThreadState : public StackObj {
1800 protected:
1801 G1CollectedHeap* _g1h;
1802 RefToScanQueue* _refs;
1803 DirtyCardQueue _dcq;
1804 CardTableModRefBS* _ct_bs;
1805 G1RemSet* _g1_rem;
1806
1807 G1ParGCAllocBuffer _surviving_alloc_buffer;
1808 G1ParGCAllocBuffer _tenured_alloc_buffer;
1809 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1810 ageTable _age_table;
1811
1812 size_t _alloc_buffer_waste;
1813 size_t _undo_waste;
1814
1815 OopsInHeapRegionClosure* _evac_failure_cl;
1816 G1ParScanHeapEvacClosure* _evac_cl;
1817 G1ParScanPartialArrayClosure* _partial_scan_cl;
1818
1819 int _hash_seed;
1820 uint _queue_num;
1821
1822 size_t _term_attempts;
1823
1824 double _start;
1825 double _start_strong_roots;
1826 double _strong_roots_time;
1827 double _start_term;
1828 double _term_time;
1829
1830 // Map from young-age-index (0 == not young, 1 is youngest) to
1831 // surviving words. base is what we get back from the malloc call
1832 size_t* _surviving_young_words_base;
1833 // this points into the array, as we use the first few entries for padding
1834 size_t* _surviving_young_words;
1835
1836 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1837
1838 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1839
1840 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1841
1842 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1843 CardTableModRefBS* ctbs() { return _ct_bs; }
1844
1845 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1846 if (!from->is_survivor()) {
1847 _g1_rem->par_write_ref(from, p, tid);
1848 }
1849 }
1850
1851 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1852 // If the new value of the field points to the same region or
1853 // is the to-space, we don't need to include it in the Rset updates.
1854 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1855 size_t card_index = ctbs()->index_for(p);
1856 // If the card hasn't been added to the buffer, do it.
1857 if (ctbs()->mark_card_deferred(card_index)) {
1858 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1859 }
1860 }
1861 }
1862
1863 public:
1864 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1865
1866 ~G1ParScanThreadState() {
1867 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1868 }
1869
1870 RefToScanQueue* refs() { return _refs; }
1871 ageTable* age_table() { return &_age_table; }
1872
1873 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1874 return _alloc_buffers[purpose];
1875 }
1876
1877 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1878 size_t undo_waste() const { return _undo_waste; }
1879
1880 #ifdef ASSERT
1881 bool verify_ref(narrowOop* ref) const;
1882 bool verify_ref(oop* ref) const;
1883 bool verify_task(StarTask ref) const;
1884 #endif // ASSERT
1885
1886 template <class T> void push_on_queue(T* ref) {
1887 assert(verify_ref(ref), "sanity");
1888 refs()->push(ref);
1889 }
1890
1891 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1892 if (G1DeferredRSUpdate) {
1893 deferred_rs_update(from, p, tid);
1894 } else {
1895 immediate_rs_update(from, p, tid);
1896 }
1897 }
1898
1899 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1900 HeapWord* obj = NULL;
1901 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1902 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1903 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1904 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1905 alloc_buf->retire(false /* end_of_gc */, false /* retain */);
1906
1907 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1908 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1909 // Otherwise.
1910 alloc_buf->set_word_size(gclab_word_size);
1911 alloc_buf->set_buf(buf);
1912
1913 obj = alloc_buf->allocate(word_sz);
1914 assert(obj != NULL, "buffer was definitely big enough...");
1915 } else {
1916 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1917 }
1918 return obj;
1919 }
1920
1921 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1922 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1923 if (obj != NULL) return obj;
1924 return allocate_slow(purpose, word_sz);
1925 }
1926
1927 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1928 if (alloc_buffer(purpose)->contains(obj)) {
1929 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1930 "should contain whole object");
1931 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1932 } else {
1933 CollectedHeap::fill_with_object(obj, word_sz);
1934 add_to_undo_waste(word_sz);
1935 }
1936 }
1937
1938 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1939 _evac_failure_cl = evac_failure_cl;
1940 }
1941 OopsInHeapRegionClosure* evac_failure_closure() {
1942 return _evac_failure_cl;
1943 }
1944
1945 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1946 _evac_cl = evac_cl;
1947 }
1948
1949 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1950 _partial_scan_cl = partial_scan_cl;
1951 }
1952
1953 int* hash_seed() { return &_hash_seed; }
1954 uint queue_num() { return _queue_num; }
1955
1956 size_t term_attempts() const { return _term_attempts; }
1957 void note_term_attempt() { _term_attempts++; }
1958
1959 void start_strong_roots() {
1960 _start_strong_roots = os::elapsedTime();
1961 }
1962 void end_strong_roots() {
1963 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1964 }
1965 double strong_roots_time() const { return _strong_roots_time; }
1966
1967 void start_term_time() {
1968 note_term_attempt();
1969 _start_term = os::elapsedTime();
1970 }
1971 void end_term_time() {
1972 _term_time += (os::elapsedTime() - _start_term);
1973 }
1974 double term_time() const { return _term_time; }
1975
1976 double elapsed_time() const {
1977 return os::elapsedTime() - _start;
1978 }
1979
1980 static void
1981 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1982 void
1983 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1984
1985 size_t* surviving_young_words() {
1986 // We add on to hide entry 0 which accumulates surviving words for
1987 // age -1 regions (i.e. non-young ones)
1988 return _surviving_young_words;
1989 }
1990
1991 void retire_alloc_buffers() {
1992 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1993 size_t waste = _alloc_buffers[ap]->words_remaining();
1994 add_to_alloc_buffer_waste(waste);
1995 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1996 true /* end_of_gc */,
1997 false /* retain */);
1998 }
1999 }
2000
2001 template <class T> void deal_with_reference(T* ref_to_scan) {
2002 if (has_partial_array_mask(ref_to_scan)) {
2003 _partial_scan_cl->do_oop_nv(ref_to_scan);
2004 } else {
2005 // Note: we can use "raw" versions of "region_containing" because
2006 // "obj_to_scan" is definitely in the heap, and is not in a
2007 // humongous region.
2008 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2009 _evac_cl->set_region(r);
2010 _evac_cl->do_oop_nv(ref_to_scan);
2011 }
2012 }
2013
2014 void deal_with_reference(StarTask ref) {
2015 assert(verify_task(ref), "sanity");
2016 if (ref.is_narrow()) {
2017 deal_with_reference((narrowOop*)ref);
2018 } else {
2019 deal_with_reference((oop*)ref);
2020 }
2021 }
2022
2023 public:
2024 void trim_queue();
2025 };
2026
2027 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP