1 /*
2 * Copyright (c) 2001, 2011, 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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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/parNew/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 PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
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> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue> 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 {
78 private:
79 G1CollectedHeap* _g1h;
80
81 HeapRegion* _head;
82
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
85
86 HeapRegion* _curr;
87
88 size_t _length;
89 size_t _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 size_t length() { return _length; }
105 size_t 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 (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return 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 class SurvivorGCAllocRegion : public G1AllocRegion {
159 protected:
160 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
161 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
162 public:
163 SurvivorGCAllocRegion()
164 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
165 };
166
167 class OldGCAllocRegion : public G1AllocRegion {
168 protected:
169 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
170 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
171 public:
172 OldGCAllocRegion()
173 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
174 };
175
176 class RefineCardTableEntryClosure;
177 class G1CollectedHeap : public SharedHeap {
178 friend class VM_G1CollectForAllocation;
179 friend class VM_GenCollectForPermanentAllocation;
180 friend class VM_G1CollectFull;
181 friend class VM_G1IncCollectionPause;
182 friend class VMStructs;
183 friend class MutatorAllocRegion;
184 friend class SurvivorGCAllocRegion;
185 friend class OldGCAllocRegion;
186
187 // Closures used in implementation.
188 friend class G1ParCopyHelper;
189 friend class G1IsAliveClosure;
190 friend class G1EvacuateFollowersClosure;
191 friend class G1ParScanThreadState;
192 friend class G1ParScanClosureSuper;
193 friend class G1ParEvacuateFollowersClosure;
194 friend class G1ParTask;
195 friend class G1FreeGarbageRegionClosure;
196 friend class RefineCardTableEntryClosure;
197 friend class G1PrepareCompactClosure;
198 friend class RegionSorter;
199 friend class RegionResetter;
200 friend class CountRCClosure;
201 friend class EvacPopObjClosure;
202 friend class G1ParCleanupCTTask;
203
204 // Other related classes.
205 friend class G1MarkSweep;
206
207 private:
208 // The one and only G1CollectedHeap, so static functions can find it.
209 static G1CollectedHeap* _g1h;
210
211 static size_t _humongous_object_threshold_in_words;
212
213 // Storage for the G1 heap (excludes the permanent generation).
214 VirtualSpace _g1_storage;
215 MemRegion _g1_reserved;
216
217 // The part of _g1_storage that is currently committed.
218 MemRegion _g1_committed;
219
220 // The master free list. It will satisfy all new region allocations.
221 MasterFreeRegionList _free_list;
222
223 // The secondary free list which contains regions that have been
224 // freed up during the cleanup process. This will be appended to the
225 // master free list when appropriate.
226 SecondaryFreeRegionList _secondary_free_list;
227
228 // It keeps track of the humongous regions.
229 MasterHumongousRegionSet _humongous_set;
230
231 // The number of regions we could create by expansion.
232 size_t _expansion_regions;
233
234 // The block offset table for the G1 heap.
235 G1BlockOffsetSharedArray* _bot_shared;
236
237 // Move all of the regions off the free lists, then rebuild those free
238 // lists, before and after full GC.
239 void tear_down_region_lists();
240 void rebuild_region_lists();
241
242 // The sequence of all heap regions in the heap.
243 HeapRegionSeq _hrs;
244
245 // Alloc region used to satisfy mutator allocation requests.
246 MutatorAllocRegion _mutator_alloc_region;
247
248 // Alloc region used to satisfy allocation requests by the GC for
249 // survivor objects.
250 SurvivorGCAllocRegion _survivor_gc_alloc_region;
251
252 // Alloc region used to satisfy allocation requests by the GC for
253 // old objects.
254 OldGCAllocRegion _old_gc_alloc_region;
255
256 // The last old region we allocated to during the last GC.
257 // Typically, it is not full so we should re-use it during the next GC.
258 HeapRegion* _retained_old_gc_alloc_region;
259
260 // It resets the mutator alloc region before new allocations can take place.
261 void init_mutator_alloc_region();
262
263 // It releases the mutator alloc region.
264 void release_mutator_alloc_region();
265
266 // It initializes the GC alloc regions at the start of a GC.
267 void init_gc_alloc_regions();
268
269 // It releases the GC alloc regions at the end of a GC.
270 void release_gc_alloc_regions();
271
272 // It does any cleanup that needs to be done on the GC alloc regions
273 // before a Full GC.
274 void abandon_gc_alloc_regions();
275
276 // Helper for monitoring and management support.
277 G1MonitoringSupport* _g1mm;
278
279 // Determines PLAB size for a particular allocation purpose.
280 static size_t desired_plab_sz(GCAllocPurpose purpose);
281
282 // Outside of GC pauses, the number of bytes used in all regions other
283 // than the current allocation region.
284 size_t _summary_bytes_used;
285
286 // This is used for a quick test on whether a reference points into
287 // the collection set or not. Basically, we have an array, with one
288 // byte per region, and that byte denotes whether the corresponding
289 // region is in the collection set or not. The entry corresponding
290 // the bottom of the heap, i.e., region 0, is pointed to by
291 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
292 // biased so that it actually points to address 0 of the address
293 // space, to make the test as fast as possible (we can simply shift
294 // the address to address into it, instead of having to subtract the
295 // bottom of the heap from the address before shifting it; basically
296 // it works in the same way the card table works).
297 bool* _in_cset_fast_test;
298
299 // The allocated array used for the fast test on whether a reference
300 // points into the collection set or not. This field is also used to
301 // free the array.
302 bool* _in_cset_fast_test_base;
303
304 // The length of the _in_cset_fast_test_base array.
305 size_t _in_cset_fast_test_length;
306
307 volatile unsigned _gc_time_stamp;
308
309 size_t* _surviving_young_words;
310
311 G1HRPrinter _hr_printer;
312
313 void setup_surviving_young_words();
314 void update_surviving_young_words(size_t* surv_young_words);
315 void cleanup_surviving_young_words();
316
317 // It decides whether an explicit GC should start a concurrent cycle
318 // instead of doing a STW GC. Currently, a concurrent cycle is
319 // explicitly started if:
320 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
321 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
322 bool should_do_concurrent_full_gc(GCCause::Cause cause);
323
324 // Keeps track of how many "full collections" (i.e., Full GCs or
325 // concurrent cycles) we have completed. The number of them we have
326 // started is maintained in _total_full_collections in CollectedHeap.
327 volatile unsigned int _full_collections_completed;
328
329 // This is a non-product method that is helpful for testing. It is
330 // called at the end of a GC and artificially expands the heap by
331 // allocating a number of dead regions. This way we can induce very
332 // frequent marking cycles and stress the cleanup / concurrent
333 // cleanup code more (as all the regions that will be allocated by
334 // this method will be found dead by the marking cycle).
335 void allocate_dummy_regions() PRODUCT_RETURN;
336
337 // These are macros so that, if the assert fires, we get the correct
338 // line number, file, etc.
339
340 #define heap_locking_asserts_err_msg(_extra_message_) \
341 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
342 (_extra_message_), \
343 BOOL_TO_STR(Heap_lock->owned_by_self()), \
344 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
345 BOOL_TO_STR(Thread::current()->is_VM_thread()))
346
347 #define assert_heap_locked() \
348 do { \
349 assert(Heap_lock->owned_by_self(), \
350 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
351 } while (0)
352
353 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
354 do { \
355 assert(Heap_lock->owned_by_self() || \
356 (SafepointSynchronize::is_at_safepoint() && \
357 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
358 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
359 "should be at a safepoint")); \
360 } while (0)
361
362 #define assert_heap_locked_and_not_at_safepoint() \
363 do { \
364 assert(Heap_lock->owned_by_self() && \
365 !SafepointSynchronize::is_at_safepoint(), \
366 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
367 "should not be at a safepoint")); \
368 } while (0)
369
370 #define assert_heap_not_locked() \
371 do { \
372 assert(!Heap_lock->owned_by_self(), \
373 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
374 } while (0)
375
376 #define assert_heap_not_locked_and_not_at_safepoint() \
377 do { \
378 assert(!Heap_lock->owned_by_self() && \
379 !SafepointSynchronize::is_at_safepoint(), \
380 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
381 "should not be at a safepoint")); \
382 } while (0)
383
384 #define assert_at_safepoint(_should_be_vm_thread_) \
385 do { \
386 assert(SafepointSynchronize::is_at_safepoint() && \
387 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
388 heap_locking_asserts_err_msg("should be at a safepoint")); \
389 } while (0)
390
391 #define assert_not_at_safepoint() \
392 do { \
393 assert(!SafepointSynchronize::is_at_safepoint(), \
394 heap_locking_asserts_err_msg("should not be at a safepoint")); \
395 } while (0)
396
397 protected:
398
399 // The young region list.
400 YoungList* _young_list;
401
402 // The current policy object for the collector.
403 G1CollectorPolicy* _g1_policy;
404
405 // This is the second level of trying to allocate a new region. If
406 // new_region() didn't find a region on the free_list, this call will
407 // check whether there's anything available on the
408 // secondary_free_list and/or wait for more regions to appear on
409 // that list, if _free_regions_coming is set.
410 HeapRegion* new_region_try_secondary_free_list();
411
412 // Try to allocate a single non-humongous HeapRegion sufficient for
413 // an allocation of the given word_size. If do_expand is true,
414 // attempt to expand the heap if necessary to satisfy the allocation
415 // request.
416 HeapRegion* new_region(size_t word_size, bool do_expand);
417
418 // Attempt to satisfy a humongous allocation request of the given
419 // size by finding a contiguous set of free regions of num_regions
420 // length and remove them from the master free list. Return the
421 // index of the first region or G1_NULL_HRS_INDEX if the search
422 // was unsuccessful.
423 size_t humongous_obj_allocate_find_first(size_t num_regions,
424 size_t word_size);
425
426 // Initialize a contiguous set of free regions of length num_regions
427 // and starting at index first so that they appear as a single
428 // humongous region.
429 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
430 size_t num_regions,
431 size_t word_size);
432
433 // Attempt to allocate a humongous object of the given size. Return
434 // NULL if unsuccessful.
435 HeapWord* humongous_obj_allocate(size_t word_size);
436
437 // The following two methods, allocate_new_tlab() and
438 // mem_allocate(), are the two main entry points from the runtime
439 // into the G1's allocation routines. They have the following
440 // assumptions:
441 //
442 // * They should both be called outside safepoints.
443 //
444 // * They should both be called without holding the Heap_lock.
445 //
446 // * All allocation requests for new TLABs should go to
447 // allocate_new_tlab().
448 //
449 // * All non-TLAB allocation requests should go to mem_allocate().
450 //
451 // * If either call cannot satisfy the allocation request using the
452 // current allocating region, they will try to get a new one. If
453 // this fails, they will attempt to do an evacuation pause and
454 // retry the allocation.
455 //
456 // * If all allocation attempts fail, even after trying to schedule
457 // an evacuation pause, allocate_new_tlab() will return NULL,
458 // whereas mem_allocate() will attempt a heap expansion and/or
459 // schedule a Full GC.
460 //
461 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
462 // should never be called with word_size being humongous. All
463 // humongous allocation requests should go to mem_allocate() which
464 // will satisfy them with a special path.
465
466 virtual HeapWord* allocate_new_tlab(size_t word_size);
467
468 virtual HeapWord* mem_allocate(size_t word_size,
469 bool* gc_overhead_limit_was_exceeded);
470
471 // The following three methods take a gc_count_before_ret
472 // parameter which is used to return the GC count if the method
473 // returns NULL. Given that we are required to read the GC count
474 // while holding the Heap_lock, and these paths will take the
475 // Heap_lock at some point, it's easier to get them to read the GC
476 // count while holding the Heap_lock before they return NULL instead
477 // of the caller (namely: mem_allocate()) having to also take the
478 // Heap_lock just to read the GC count.
479
480 // First-level mutator allocation attempt: try to allocate out of
481 // the mutator alloc region without taking the Heap_lock. This
482 // should only be used for non-humongous allocations.
483 inline HeapWord* attempt_allocation(size_t word_size,
484 unsigned int* gc_count_before_ret);
485
486 // Second-level mutator allocation attempt: take the Heap_lock and
487 // retry the allocation attempt, potentially scheduling a GC
488 // pause. This should only be used for non-humongous allocations.
489 HeapWord* attempt_allocation_slow(size_t word_size,
490 unsigned int* gc_count_before_ret);
491
492 // Takes the Heap_lock and attempts a humongous allocation. It can
493 // potentially schedule a GC pause.
494 HeapWord* attempt_allocation_humongous(size_t word_size,
495 unsigned int* gc_count_before_ret);
496
497 // Allocation attempt that should be called during safepoints (e.g.,
498 // at the end of a successful GC). expect_null_mutator_alloc_region
499 // specifies whether the mutator alloc region is expected to be NULL
500 // or not.
501 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
502 bool expect_null_mutator_alloc_region);
503
504 // It dirties the cards that cover the block so that so that the post
505 // write barrier never queues anything when updating objects on this
506 // block. It is assumed (and in fact we assert) that the block
507 // belongs to a young region.
508 inline void dirty_young_block(HeapWord* start, size_t word_size);
509
510 // Allocate blocks during garbage collection. Will ensure an
511 // allocation region, either by picking one or expanding the
512 // heap, and then allocate a block of the given size. The block
513 // may not be a humongous - it must fit into a single heap region.
514 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
515
516 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
517 HeapRegion* alloc_region,
518 bool par,
519 size_t word_size);
520
521 // Ensure that no further allocations can happen in "r", bearing in mind
522 // that parallel threads might be attempting allocations.
523 void par_allocate_remaining_space(HeapRegion* r);
524
525 // Allocation attempt during GC for a survivor object / PLAB.
526 inline HeapWord* survivor_attempt_allocation(size_t word_size);
527
528 // Allocation attempt during GC for an old object / PLAB.
529 inline HeapWord* old_attempt_allocation(size_t word_size);
530
531 // These methods are the "callbacks" from the G1AllocRegion class.
532
533 // For mutator alloc regions.
534 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
535 void retire_mutator_alloc_region(HeapRegion* alloc_region,
536 size_t allocated_bytes);
537
538 // For GC alloc regions.
539 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
540 GCAllocPurpose ap);
541 void retire_gc_alloc_region(HeapRegion* alloc_region,
542 size_t allocated_bytes, GCAllocPurpose ap);
543
544 // - if explicit_gc is true, the GC is for a System.gc() or a heap
545 // inspection request and should collect the entire heap
546 // - if clear_all_soft_refs is true, all soft references should be
547 // cleared during the GC
548 // - if explicit_gc is false, word_size describes the allocation that
549 // the GC should attempt (at least) to satisfy
550 // - it returns false if it is unable to do the collection due to the
551 // GC locker being active, true otherwise
552 bool do_collection(bool explicit_gc,
553 bool clear_all_soft_refs,
554 size_t word_size);
555
556 // Callback from VM_G1CollectFull operation.
557 // Perform a full collection.
558 void do_full_collection(bool clear_all_soft_refs);
559
560 // Resize the heap if necessary after a full collection. If this is
561 // after a collect-for allocation, "word_size" is the allocation size,
562 // and will be considered part of the used portion of the heap.
563 void resize_if_necessary_after_full_collection(size_t word_size);
564
565 // Callback from VM_G1CollectForAllocation operation.
566 // This function does everything necessary/possible to satisfy a
567 // failed allocation request (including collection, expansion, etc.)
568 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
569
570 // Attempting to expand the heap sufficiently
571 // to support an allocation of the given "word_size". If
572 // successful, perform the allocation and return the address of the
573 // allocated block, or else "NULL".
574 HeapWord* expand_and_allocate(size_t word_size);
575
576 public:
577
578 G1MonitoringSupport* g1mm() { return _g1mm; }
579
580 // Expand the garbage-first heap by at least the given size (in bytes!).
581 // Returns true if the heap was expanded by the requested amount;
582 // false otherwise.
583 // (Rounds up to a HeapRegion boundary.)
584 bool expand(size_t expand_bytes);
585
586 // Do anything common to GC's.
587 virtual void gc_prologue(bool full);
588 virtual void gc_epilogue(bool full);
589
590 // We register a region with the fast "in collection set" test. We
591 // simply set to true the array slot corresponding to this region.
592 void register_region_with_in_cset_fast_test(HeapRegion* r) {
593 assert(_in_cset_fast_test_base != NULL, "sanity");
594 assert(r->in_collection_set(), "invariant");
595 size_t index = r->hrs_index();
596 assert(index < _in_cset_fast_test_length, "invariant");
597 assert(!_in_cset_fast_test_base[index], "invariant");
598 _in_cset_fast_test_base[index] = true;
599 }
600
601 // This is a fast test on whether a reference points into the
602 // collection set or not. It does not assume that the reference
603 // points into the heap; if it doesn't, it will return false.
604 bool in_cset_fast_test(oop obj) {
605 assert(_in_cset_fast_test != NULL, "sanity");
606 if (_g1_committed.contains((HeapWord*) obj)) {
607 // no need to subtract the bottom of the heap from obj,
608 // _in_cset_fast_test is biased
609 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
610 bool ret = _in_cset_fast_test[index];
611 // let's make sure the result is consistent with what the slower
612 // test returns
613 assert( ret || !obj_in_cs(obj), "sanity");
614 assert(!ret || obj_in_cs(obj), "sanity");
615 return ret;
616 } else {
617 return false;
618 }
619 }
620
621 void clear_cset_fast_test() {
622 assert(_in_cset_fast_test_base != NULL, "sanity");
623 memset(_in_cset_fast_test_base, false,
624 _in_cset_fast_test_length * sizeof(bool));
625 }
626
627 // This is called at the end of either a concurrent cycle or a Full
628 // GC to update the number of full collections completed. Those two
629 // can happen in a nested fashion, i.e., we start a concurrent
630 // cycle, a Full GC happens half-way through it which ends first,
631 // and then the cycle notices that a Full GC happened and ends
632 // too. The concurrent parameter is a boolean to help us do a bit
633 // tighter consistency checking in the method. If concurrent is
634 // false, the caller is the inner caller in the nesting (i.e., the
635 // Full GC). If concurrent is true, the caller is the outer caller
636 // in this nesting (i.e., the concurrent cycle). Further nesting is
637 // not currently supported. The end of the this call also notifies
638 // the FullGCCount_lock in case a Java thread is waiting for a full
639 // GC to happen (e.g., it called System.gc() with
640 // +ExplicitGCInvokesConcurrent).
641 void increment_full_collections_completed(bool concurrent);
642
643 unsigned int full_collections_completed() {
644 return _full_collections_completed;
645 }
646
647 G1HRPrinter* hr_printer() { return &_hr_printer; }
648
649 protected:
650
651 // Shrink the garbage-first heap by at most the given size (in bytes!).
652 // (Rounds down to a HeapRegion boundary.)
653 virtual void shrink(size_t expand_bytes);
654 void shrink_helper(size_t expand_bytes);
655
656 #if TASKQUEUE_STATS
657 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
658 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
659 void reset_taskqueue_stats();
660 #endif // TASKQUEUE_STATS
661
662 // Schedule the VM operation that will do an evacuation pause to
663 // satisfy an allocation request of word_size. *succeeded will
664 // return whether the VM operation was successful (it did do an
665 // evacuation pause) or not (another thread beat us to it or the GC
666 // locker was active). Given that we should not be holding the
667 // Heap_lock when we enter this method, we will pass the
668 // gc_count_before (i.e., total_collections()) as a parameter since
669 // it has to be read while holding the Heap_lock. Currently, both
670 // methods that call do_collection_pause() release the Heap_lock
671 // before the call, so it's easy to read gc_count_before just before.
672 HeapWord* do_collection_pause(size_t word_size,
673 unsigned int gc_count_before,
674 bool* succeeded);
675
676 // The guts of the incremental collection pause, executed by the vm
677 // thread. It returns false if it is unable to do the collection due
678 // to the GC locker being active, true otherwise
679 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
680
681 // Actually do the work of evacuating the collection set.
682 void evacuate_collection_set();
683
684 // The g1 remembered set of the heap.
685 G1RemSet* _g1_rem_set;
686 // And it's mod ref barrier set, used to track updates for the above.
687 ModRefBarrierSet* _mr_bs;
688
689 // A set of cards that cover the objects for which the Rsets should be updated
690 // concurrently after the collection.
691 DirtyCardQueueSet _dirty_card_queue_set;
692
693 // The Heap Region Rem Set Iterator.
694 HeapRegionRemSetIterator** _rem_set_iterator;
695
696 // The closure used to refine a single card.
697 RefineCardTableEntryClosure* _refine_cte_cl;
698
699 // A function to check the consistency of dirty card logs.
700 void check_ct_logs_at_safepoint();
701
702 // A DirtyCardQueueSet that is used to hold cards that contain
703 // references into the current collection set. This is used to
704 // update the remembered sets of the regions in the collection
705 // set in the event of an evacuation failure.
706 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
707
708 // After a collection pause, make the regions in the CS into free
709 // regions.
710 void free_collection_set(HeapRegion* cs_head);
711
712 // Abandon the current collection set without recording policy
713 // statistics or updating free lists.
714 void abandon_collection_set(HeapRegion* cs_head);
715
716 // Applies "scan_non_heap_roots" to roots outside the heap,
717 // "scan_rs" to roots inside the heap (having done "set_region" to
718 // indicate the region in which the root resides), and does "scan_perm"
719 // (setting the generation to the perm generation.) If "scan_rs" is
720 // NULL, then this step is skipped. The "worker_i"
721 // param is for use with parallel roots processing, and should be
722 // the "i" of the calling parallel worker thread's work(i) function.
723 // In the sequential case this param will be ignored.
724 void g1_process_strong_roots(bool collecting_perm_gen,
725 SharedHeap::ScanningOption so,
726 OopClosure* scan_non_heap_roots,
727 OopsInHeapRegionClosure* scan_rs,
728 OopsInGenClosure* scan_perm,
729 int worker_i);
730
731 // Apply "blk" to all the weak roots of the system. These include
732 // JNI weak roots, the code cache, system dictionary, symbol table,
733 // string table, and referents of reachable weak refs.
734 void g1_process_weak_roots(OopClosure* root_closure,
735 OopClosure* non_root_closure);
736
737 // Frees a non-humongous region by initializing its contents and
738 // adding it to the free list that's passed as a parameter (this is
739 // usually a local list which will be appended to the master free
740 // list later). The used bytes of freed regions are accumulated in
741 // pre_used. If par is true, the region's RSet will not be freed
742 // up. The assumption is that this will be done later.
743 void free_region(HeapRegion* hr,
744 size_t* pre_used,
745 FreeRegionList* free_list,
746 bool par);
747
748 // Frees a humongous region by collapsing it into individual regions
749 // and calling free_region() for each of them. The freed regions
750 // will be added to the free list that's passed as a parameter (this
751 // is usually a local list which will be appended to the master free
752 // list later). The used bytes of freed regions are accumulated in
753 // pre_used. If par is true, the region's RSet will not be freed
754 // up. The assumption is that this will be done later.
755 void free_humongous_region(HeapRegion* hr,
756 size_t* pre_used,
757 FreeRegionList* free_list,
758 HumongousRegionSet* humongous_proxy_set,
759 bool par);
760
761 // Notifies all the necessary spaces that the committed space has
762 // been updated (either expanded or shrunk). It should be called
763 // after _g1_storage is updated.
764 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
765
766 // The concurrent marker (and the thread it runs in.)
767 ConcurrentMark* _cm;
768 ConcurrentMarkThread* _cmThread;
769 bool _mark_in_progress;
770
771 // The concurrent refiner.
772 ConcurrentG1Refine* _cg1r;
773
774 // The parallel task queues
775 RefToScanQueueSet *_task_queues;
776
777 // True iff a evacuation has failed in the current collection.
778 bool _evacuation_failed;
779
780 // Set the attribute indicating whether evacuation has failed in the
781 // current collection.
782 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
783
784 // Failed evacuations cause some logical from-space objects to have
785 // forwarding pointers to themselves. Reset them.
786 void remove_self_forwarding_pointers();
787
788 // When one is non-null, so is the other. Together, they each pair is
789 // an object with a preserved mark, and its mark value.
790 GrowableArray<oop>* _objs_with_preserved_marks;
791 GrowableArray<markOop>* _preserved_marks_of_objs;
792
793 // Preserve the mark of "obj", if necessary, in preparation for its mark
794 // word being overwritten with a self-forwarding-pointer.
795 void preserve_mark_if_necessary(oop obj, markOop m);
796
797 // The stack of evac-failure objects left to be scanned.
798 GrowableArray<oop>* _evac_failure_scan_stack;
799 // The closure to apply to evac-failure objects.
800
801 OopsInHeapRegionClosure* _evac_failure_closure;
802 // Set the field above.
803 void
804 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
805 _evac_failure_closure = evac_failure_closure;
806 }
807
808 // Push "obj" on the scan stack.
809 void push_on_evac_failure_scan_stack(oop obj);
810 // Process scan stack entries until the stack is empty.
811 void drain_evac_failure_scan_stack();
812 // True iff an invocation of "drain_scan_stack" is in progress; to
813 // prevent unnecessary recursion.
814 bool _drain_in_progress;
815
816 // Do any necessary initialization for evacuation-failure handling.
817 // "cl" is the closure that will be used to process evac-failure
818 // objects.
819 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
820 // Do any necessary cleanup for evacuation-failure handling data
821 // structures.
822 void finalize_for_evac_failure();
823
824 // An attempt to evacuate "obj" has failed; take necessary steps.
825 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
826 void handle_evacuation_failure_common(oop obj, markOop m);
827
828 // Instance of the concurrent mark is_alive closure for embedding
829 // into the reference processor as the is_alive_non_header. This
830 // prevents unnecessary additions to the discovered lists during
831 // concurrent discovery.
832 G1CMIsAliveClosure _is_alive_closure;
833
834 // ("Weak") Reference processing support
835 ReferenceProcessor* _ref_processor;
836
837 enum G1H_process_strong_roots_tasks {
838 G1H_PS_mark_stack_oops_do,
839 G1H_PS_refProcessor_oops_do,
840 // Leave this one last.
841 G1H_PS_NumElements
842 };
843
844 SubTasksDone* _process_strong_tasks;
845
846 volatile bool _free_regions_coming;
847
848 public:
849
850 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
851
852 void set_refine_cte_cl_concurrency(bool concurrent);
853
854 RefToScanQueue *task_queue(int i) const;
855
856 // A set of cards where updates happened during the GC
857 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
858
859 // A DirtyCardQueueSet that is used to hold cards that contain
860 // references into the current collection set. This is used to
861 // update the remembered sets of the regions in the collection
862 // set in the event of an evacuation failure.
863 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
864 { return _into_cset_dirty_card_queue_set; }
865
866 // Create a G1CollectedHeap with the specified policy.
867 // Must call the initialize method afterwards.
868 // May not return if something goes wrong.
869 G1CollectedHeap(G1CollectorPolicy* policy);
870
871 // Initialize the G1CollectedHeap to have the initial and
872 // maximum sizes, permanent generation, and remembered and barrier sets
873 // specified by the policy object.
874 jint initialize();
875
876 virtual void ref_processing_init();
877
878 void set_par_threads(int t) {
879 SharedHeap::set_par_threads(t);
880 _process_strong_tasks->set_n_threads(t);
881 }
882
883 virtual CollectedHeap::Name kind() const {
884 return CollectedHeap::G1CollectedHeap;
885 }
886
887 // The current policy object for the collector.
888 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
889
890 // Adaptive size policy. No such thing for g1.
891 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
892
893 // The rem set and barrier set.
894 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
895 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
896
897 // The rem set iterator.
898 HeapRegionRemSetIterator* rem_set_iterator(int i) {
899 return _rem_set_iterator[i];
900 }
901
902 HeapRegionRemSetIterator* rem_set_iterator() {
903 return _rem_set_iterator[0];
904 }
905
906 unsigned get_gc_time_stamp() {
907 return _gc_time_stamp;
908 }
909
910 void reset_gc_time_stamp() {
911 _gc_time_stamp = 0;
912 OrderAccess::fence();
913 }
914
915 void increment_gc_time_stamp() {
916 ++_gc_time_stamp;
917 OrderAccess::fence();
918 }
919
920 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
921 DirtyCardQueue* into_cset_dcq,
922 bool concurrent, int worker_i);
923
924 // The shared block offset table array.
925 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
926
927 // Reference Processing accessor
928 ReferenceProcessor* ref_processor() { return _ref_processor; }
929
930 virtual size_t capacity() const;
931 virtual size_t used() const;
932 // This should be called when we're not holding the heap lock. The
933 // result might be a bit inaccurate.
934 size_t used_unlocked() const;
935 size_t recalculate_used() const;
936
937 // These virtual functions do the actual allocation.
938 // Some heaps may offer a contiguous region for shared non-blocking
939 // allocation, via inlined code (by exporting the address of the top and
940 // end fields defining the extent of the contiguous allocation region.)
941 // But G1CollectedHeap doesn't yet support this.
942
943 // Return an estimate of the maximum allocation that could be performed
944 // without triggering any collection or expansion activity. In a
945 // generational collector, for example, this is probably the largest
946 // allocation that could be supported (without expansion) in the youngest
947 // generation. It is "unsafe" because no locks are taken; the result
948 // should be treated as an approximation, not a guarantee, for use in
949 // heuristic resizing decisions.
950 virtual size_t unsafe_max_alloc();
951
952 virtual bool is_maximal_no_gc() const {
953 return _g1_storage.uncommitted_size() == 0;
954 }
955
956 // The total number of regions in the heap.
957 size_t n_regions() { return _hrs.length(); }
958
959 // The max number of regions in the heap.
960 size_t max_regions() { return _hrs.max_length(); }
961
962 // The number of regions that are completely free.
963 size_t free_regions() { return _free_list.length(); }
964
965 // The number of regions that are not completely free.
966 size_t used_regions() { return n_regions() - free_regions(); }
967
968 // The number of regions available for "regular" expansion.
969 size_t expansion_regions() { return _expansion_regions; }
970
971 // Factory method for HeapRegion instances. It will return NULL if
972 // the allocation fails.
973 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
974
975 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
976 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
977 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
978 void verify_dirty_young_regions() PRODUCT_RETURN;
979
980 // verify_region_sets() performs verification over the region
981 // lists. It will be compiled in the product code to be used when
982 // necessary (i.e., during heap verification).
983 void verify_region_sets();
984
985 // verify_region_sets_optional() is planted in the code for
986 // list verification in non-product builds (and it can be enabled in
987 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
988 #if HEAP_REGION_SET_FORCE_VERIFY
989 void verify_region_sets_optional() {
990 verify_region_sets();
991 }
992 #else // HEAP_REGION_SET_FORCE_VERIFY
993 void verify_region_sets_optional() { }
994 #endif // HEAP_REGION_SET_FORCE_VERIFY
995
996 #ifdef ASSERT
997 bool is_on_master_free_list(HeapRegion* hr) {
998 return hr->containing_set() == &_free_list;
999 }
1000
1001 bool is_in_humongous_set(HeapRegion* hr) {
1002 return hr->containing_set() == &_humongous_set;
1003 }
1004 #endif // ASSERT
1005
1006 // Wrapper for the region list operations that can be called from
1007 // methods outside this class.
1008
1009 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1010 _secondary_free_list.add_as_tail(list);
1011 }
1012
1013 void append_secondary_free_list() {
1014 _free_list.add_as_head(&_secondary_free_list);
1015 }
1016
1017 void append_secondary_free_list_if_not_empty_with_lock() {
1018 // If the secondary free list looks empty there's no reason to
1019 // take the lock and then try to append it.
1020 if (!_secondary_free_list.is_empty()) {
1021 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1022 append_secondary_free_list();
1023 }
1024 }
1025
1026 void set_free_regions_coming();
1027 void reset_free_regions_coming();
1028 bool free_regions_coming() { return _free_regions_coming; }
1029 void wait_while_free_regions_coming();
1030
1031 // Perform a collection of the heap; intended for use in implementing
1032 // "System.gc". This probably implies as full a collection as the
1033 // "CollectedHeap" supports.
1034 virtual void collect(GCCause::Cause cause);
1035
1036 // The same as above but assume that the caller holds the Heap_lock.
1037 void collect_locked(GCCause::Cause cause);
1038
1039 // This interface assumes that it's being called by the
1040 // vm thread. It collects the heap assuming that the
1041 // heap lock is already held and that we are executing in
1042 // the context of the vm thread.
1043 virtual void collect_as_vm_thread(GCCause::Cause cause);
1044
1045 // True iff a evacuation has failed in the most-recent collection.
1046 bool evacuation_failed() { return _evacuation_failed; }
1047
1048 // It will free a region if it has allocated objects in it that are
1049 // all dead. It calls either free_region() or
1050 // free_humongous_region() depending on the type of the region that
1051 // is passed to it.
1052 void free_region_if_empty(HeapRegion* hr,
1053 size_t* pre_used,
1054 FreeRegionList* free_list,
1055 HumongousRegionSet* humongous_proxy_set,
1056 HRRSCleanupTask* hrrs_cleanup_task,
1057 bool par);
1058
1059 // It appends the free list to the master free list and updates the
1060 // master humongous list according to the contents of the proxy
1061 // list. It also adjusts the total used bytes according to pre_used
1062 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1063 void update_sets_after_freeing_regions(size_t pre_used,
1064 FreeRegionList* free_list,
1065 HumongousRegionSet* humongous_proxy_set,
1066 bool par);
1067
1068 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1069 virtual bool is_in(const void* p) const;
1070
1071 // Return "TRUE" iff the given object address is within the collection
1072 // set.
1073 inline bool obj_in_cs(oop obj);
1074
1075 // Return "TRUE" iff the given object address is in the reserved
1076 // region of g1 (excluding the permanent generation).
1077 bool is_in_g1_reserved(const void* p) const {
1078 return _g1_reserved.contains(p);
1079 }
1080
1081 // Returns a MemRegion that corresponds to the space that has been
1082 // reserved for the heap
1083 MemRegion g1_reserved() {
1084 return _g1_reserved;
1085 }
1086
1087 // Returns a MemRegion that corresponds to the space that has been
1088 // committed in the heap
1089 MemRegion g1_committed() {
1090 return _g1_committed;
1091 }
1092
1093 virtual bool is_in_closed_subset(const void* p) const;
1094
1095 // This resets the card table to all zeros. It is used after
1096 // a collection pause which used the card table to claim cards.
1097 void cleanUpCardTable();
1098
1099 // Iteration functions.
1100
1101 // Iterate over all the ref-containing fields of all objects, calling
1102 // "cl.do_oop" on each.
1103 virtual void oop_iterate(OopClosure* cl) {
1104 oop_iterate(cl, true);
1105 }
1106 void oop_iterate(OopClosure* cl, bool do_perm);
1107
1108 // Same as above, restricted to a memory region.
1109 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1110 oop_iterate(mr, cl, true);
1111 }
1112 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1113
1114 // Iterate over all objects, calling "cl.do_object" on each.
1115 virtual void object_iterate(ObjectClosure* cl) {
1116 object_iterate(cl, true);
1117 }
1118 virtual void safe_object_iterate(ObjectClosure* cl) {
1119 object_iterate(cl, true);
1120 }
1121 void object_iterate(ObjectClosure* cl, bool do_perm);
1122
1123 // Iterate over all objects allocated since the last collection, calling
1124 // "cl.do_object" on each. The heap must have been initialized properly
1125 // to support this function, or else this call will fail.
1126 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1127
1128 // Iterate over all spaces in use in the heap, in ascending address order.
1129 virtual void space_iterate(SpaceClosure* cl);
1130
1131 // Iterate over heap regions, in address order, terminating the
1132 // iteration early if the "doHeapRegion" method returns "true".
1133 void heap_region_iterate(HeapRegionClosure* blk) const;
1134
1135 // Iterate over heap regions starting with r (or the first region if "r"
1136 // is NULL), in address order, terminating early if the "doHeapRegion"
1137 // method returns "true".
1138 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1139
1140 // Return the region with the given index. It assumes the index is valid.
1141 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1142
1143 // Divide the heap region sequence into "chunks" of some size (the number
1144 // of regions divided by the number of parallel threads times some
1145 // overpartition factor, currently 4). Assumes that this will be called
1146 // in parallel by ParallelGCThreads worker threads with discinct worker
1147 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1148 // calls will use the same "claim_value", and that that claim value is
1149 // different from the claim_value of any heap region before the start of
1150 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1151 // attempting to claim the first region in each chunk, and, if
1152 // successful, applying the closure to each region in the chunk (and
1153 // setting the claim value of the second and subsequent regions of the
1154 // chunk.) For now requires that "doHeapRegion" always returns "false",
1155 // i.e., that a closure never attempt to abort a traversal.
1156 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1157 int worker,
1158 jint claim_value);
1159
1160 // It resets all the region claim values to the default.
1161 void reset_heap_region_claim_values();
1162
1163 #ifdef ASSERT
1164 bool check_heap_region_claim_values(jint claim_value);
1165 #endif // ASSERT
1166
1167 // Iterate over the regions (if any) in the current collection set.
1168 void collection_set_iterate(HeapRegionClosure* blk);
1169
1170 // As above but starting from region r
1171 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1172
1173 // Returns the first (lowest address) compactible space in the heap.
1174 virtual CompactibleSpace* first_compactible_space();
1175
1176 // A CollectedHeap will contain some number of spaces. This finds the
1177 // space containing a given address, or else returns NULL.
1178 virtual Space* space_containing(const void* addr) const;
1179
1180 // A G1CollectedHeap will contain some number of heap regions. This
1181 // finds the region containing a given address, or else returns NULL.
1182 template <class T>
1183 inline HeapRegion* heap_region_containing(const T addr) const;
1184
1185 // Like the above, but requires "addr" to be in the heap (to avoid a
1186 // null-check), and unlike the above, may return an continuing humongous
1187 // region.
1188 template <class T>
1189 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1190
1191 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1192 // each address in the (reserved) heap is a member of exactly
1193 // one block. The defining characteristic of a block is that it is
1194 // possible to find its size, and thus to progress forward to the next
1195 // block. (Blocks may be of different sizes.) Thus, blocks may
1196 // represent Java objects, or they might be free blocks in a
1197 // free-list-based heap (or subheap), as long as the two kinds are
1198 // distinguishable and the size of each is determinable.
1199
1200 // Returns the address of the start of the "block" that contains the
1201 // address "addr". We say "blocks" instead of "object" since some heaps
1202 // may not pack objects densely; a chunk may either be an object or a
1203 // non-object.
1204 virtual HeapWord* block_start(const void* addr) const;
1205
1206 // Requires "addr" to be the start of a chunk, and returns its size.
1207 // "addr + size" is required to be the start of a new chunk, or the end
1208 // of the active area of the heap.
1209 virtual size_t block_size(const HeapWord* addr) const;
1210
1211 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1212 // the block is an object.
1213 virtual bool block_is_obj(const HeapWord* addr) const;
1214
1215 // Does this heap support heap inspection? (+PrintClassHistogram)
1216 virtual bool supports_heap_inspection() const { return true; }
1217
1218 // Section on thread-local allocation buffers (TLABs)
1219 // See CollectedHeap for semantics.
1220
1221 virtual bool supports_tlab_allocation() const;
1222 virtual size_t tlab_capacity(Thread* thr) const;
1223 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1224
1225 // Can a compiler initialize a new object without store barriers?
1226 // This permission only extends from the creation of a new object
1227 // via a TLAB up to the first subsequent safepoint. If such permission
1228 // is granted for this heap type, the compiler promises to call
1229 // defer_store_barrier() below on any slow path allocation of
1230 // a new object for which such initializing store barriers will
1231 // have been elided. G1, like CMS, allows this, but should be
1232 // ready to provide a compensating write barrier as necessary
1233 // if that storage came out of a non-young region. The efficiency
1234 // of this implementation depends crucially on being able to
1235 // answer very efficiently in constant time whether a piece of
1236 // storage in the heap comes from a young region or not.
1237 // See ReduceInitialCardMarks.
1238 virtual bool can_elide_tlab_store_barriers() const {
1239 // 6920090: Temporarily disabled, because of lingering
1240 // instabilities related to RICM with G1. In the
1241 // interim, the option ReduceInitialCardMarksForG1
1242 // below is left solely as a debugging device at least
1243 // until 6920109 fixes the instabilities.
1244 return ReduceInitialCardMarksForG1;
1245 }
1246
1247 virtual bool card_mark_must_follow_store() const {
1248 return true;
1249 }
1250
1251 bool is_in_young(const oop obj) {
1252 HeapRegion* hr = heap_region_containing(obj);
1253 return hr != NULL && hr->is_young();
1254 }
1255
1256 #ifdef ASSERT
1257 virtual bool is_in_partial_collection(const void* p);
1258 #endif
1259
1260 virtual bool is_scavengable(const void* addr);
1261
1262 // We don't need barriers for initializing stores to objects
1263 // in the young gen: for the SATB pre-barrier, there is no
1264 // pre-value that needs to be remembered; for the remembered-set
1265 // update logging post-barrier, we don't maintain remembered set
1266 // information for young gen objects.
1267 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1268 // Re 6920090, 6920109 above.
1269 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1270 return is_in_young(new_obj);
1271 }
1272
1273 // Can a compiler elide a store barrier when it writes
1274 // a permanent oop into the heap? Applies when the compiler
1275 // is storing x to the heap, where x->is_perm() is true.
1276 virtual bool can_elide_permanent_oop_store_barriers() const {
1277 // At least until perm gen collection is also G1-ified, at
1278 // which point this should return false.
1279 return true;
1280 }
1281
1282 // Returns "true" iff the given word_size is "very large".
1283 static bool isHumongous(size_t word_size) {
1284 // Note this has to be strictly greater-than as the TLABs
1285 // are capped at the humongous thresold and we want to
1286 // ensure that we don't try to allocate a TLAB as
1287 // humongous and that we don't allocate a humongous
1288 // object in a TLAB.
1289 return word_size > _humongous_object_threshold_in_words;
1290 }
1291
1292 // Update mod union table with the set of dirty cards.
1293 void updateModUnion();
1294
1295 // Set the mod union bits corresponding to the given memRegion. Note
1296 // that this is always a safe operation, since it doesn't clear any
1297 // bits.
1298 void markModUnionRange(MemRegion mr);
1299
1300 // Records the fact that a marking phase is no longer in progress.
1301 void set_marking_complete() {
1302 _mark_in_progress = false;
1303 }
1304 void set_marking_started() {
1305 _mark_in_progress = true;
1306 }
1307 bool mark_in_progress() {
1308 return _mark_in_progress;
1309 }
1310
1311 // Print the maximum heap capacity.
1312 virtual size_t max_capacity() const;
1313
1314 virtual jlong millis_since_last_gc();
1315
1316 // Perform any cleanup actions necessary before allowing a verification.
1317 virtual void prepare_for_verify();
1318
1319 // Perform verification.
1320
1321 // vo == UsePrevMarking -> use "prev" marking information,
1322 // vo == UseNextMarking -> use "next" marking information
1323 // vo == UseMarkWord -> use the mark word in the object header
1324 //
1325 // NOTE: Only the "prev" marking information is guaranteed to be
1326 // consistent most of the time, so most calls to this should use
1327 // vo == UsePrevMarking.
1328 // Currently, there is only one case where this is called with
1329 // vo == UseNextMarking, which is to verify the "next" marking
1330 // information at the end of remark.
1331 // Currently there is only one place where this is called with
1332 // vo == UseMarkWord, which is to verify the marking during a
1333 // full GC.
1334 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1335
1336 // Override; it uses the "prev" marking information
1337 virtual void verify(bool allow_dirty, bool silent);
1338 // Default behavior by calling print(tty);
1339 virtual void print() const;
1340 // This calls print_on(st, PrintHeapAtGCExtended).
1341 virtual void print_on(outputStream* st) const;
1342 // If extended is true, it will print out information for all
1343 // regions in the heap by calling print_on_extended(st).
1344 virtual void print_on(outputStream* st, bool extended) const;
1345 virtual void print_on_extended(outputStream* st) const;
1346
1347 virtual void print_gc_threads_on(outputStream* st) const;
1348 virtual void gc_threads_do(ThreadClosure* tc) const;
1349
1350 // Override
1351 void print_tracing_info() const;
1352
1353 // The following two methods are helpful for debugging RSet issues.
1354 void print_cset_rsets() PRODUCT_RETURN;
1355 void print_all_rsets() PRODUCT_RETURN;
1356
1357 // Convenience function to be used in situations where the heap type can be
1358 // asserted to be this type.
1359 static G1CollectedHeap* heap();
1360
1361 void empty_young_list();
1362
1363 void set_region_short_lived_locked(HeapRegion* hr);
1364 // add appropriate methods for any other surv rate groups
1365
1366 YoungList* young_list() { return _young_list; }
1367
1368 // debugging
1369 bool check_young_list_well_formed() {
1370 return _young_list->check_list_well_formed();
1371 }
1372
1373 bool check_young_list_empty(bool check_heap,
1374 bool check_sample = true);
1375
1376 // *** Stuff related to concurrent marking. It's not clear to me that so
1377 // many of these need to be public.
1378
1379 // The functions below are helper functions that a subclass of
1380 // "CollectedHeap" can use in the implementation of its virtual
1381 // functions.
1382 // This performs a concurrent marking of the live objects in a
1383 // bitmap off to the side.
1384 void doConcurrentMark();
1385
1386 bool isMarkedPrev(oop obj) const;
1387 bool isMarkedNext(oop obj) const;
1388
1389 // vo == UsePrevMarking -> use "prev" marking information,
1390 // vo == UseNextMarking -> use "next" marking information,
1391 // vo == UseMarkWord -> use mark word from object header
1392 bool is_obj_dead_cond(const oop obj,
1393 const HeapRegion* hr,
1394 const VerifyOption vo) const {
1395
1396 switch (vo) {
1397 case VerifyOption_G1UsePrevMarking:
1398 return is_obj_dead(obj, hr);
1399 case VerifyOption_G1UseNextMarking:
1400 return is_obj_ill(obj, hr);
1401 default:
1402 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1403 return !obj->is_gc_marked();
1404 }
1405 }
1406
1407 // Determine if an object is dead, given the object and also
1408 // the region to which the object belongs. An object is dead
1409 // iff a) it was not allocated since the last mark and b) it
1410 // is not marked.
1411
1412 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1413 return
1414 !hr->obj_allocated_since_prev_marking(obj) &&
1415 !isMarkedPrev(obj);
1416 }
1417
1418 // This is used when copying an object to survivor space.
1419 // If the object is marked live, then we mark the copy live.
1420 // If the object is allocated since the start of this mark
1421 // cycle, then we mark the copy live.
1422 // If the object has been around since the previous mark
1423 // phase, and hasn't been marked yet during this phase,
1424 // then we don't mark it, we just wait for the
1425 // current marking cycle to get to it.
1426
1427 // This function returns true when an object has been
1428 // around since the previous marking and hasn't yet
1429 // been marked during this marking.
1430
1431 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1432 return
1433 !hr->obj_allocated_since_next_marking(obj) &&
1434 !isMarkedNext(obj);
1435 }
1436
1437 // Determine if an object is dead, given only the object itself.
1438 // This will find the region to which the object belongs and
1439 // then call the region version of the same function.
1440
1441 // Added if it is in permanent gen it isn't dead.
1442 // Added if it is NULL it isn't dead.
1443
1444 // vo == UsePrevMarking -> use "prev" marking information,
1445 // vo == UseNextMarking -> use "next" marking information,
1446 // vo == UseMarkWord -> use mark word from object header
1447 bool is_obj_dead_cond(const oop obj,
1448 const VerifyOption vo) const {
1449
1450 switch (vo) {
1451 case VerifyOption_G1UsePrevMarking:
1452 return is_obj_dead(obj);
1453 case VerifyOption_G1UseNextMarking:
1454 return is_obj_ill(obj);
1455 default:
1456 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1457 return !obj->is_gc_marked();
1458 }
1459 }
1460
1461 bool is_obj_dead(const oop obj) const {
1462 const HeapRegion* hr = heap_region_containing(obj);
1463 if (hr == NULL) {
1464 if (Universe::heap()->is_in_permanent(obj))
1465 return false;
1466 else if (obj == NULL) return false;
1467 else return true;
1468 }
1469 else return is_obj_dead(obj, hr);
1470 }
1471
1472 bool is_obj_ill(const oop obj) const {
1473 const HeapRegion* hr = heap_region_containing(obj);
1474 if (hr == NULL) {
1475 if (Universe::heap()->is_in_permanent(obj))
1476 return false;
1477 else if (obj == NULL) return false;
1478 else return true;
1479 }
1480 else return is_obj_ill(obj, hr);
1481 }
1482
1483 // The following is just to alert the verification code
1484 // that a full collection has occurred and that the
1485 // remembered sets are no longer up to date.
1486 bool _full_collection;
1487 void set_full_collection() { _full_collection = true;}
1488 void clear_full_collection() {_full_collection = false;}
1489 bool full_collection() {return _full_collection;}
1490
1491 ConcurrentMark* concurrent_mark() const { return _cm; }
1492 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1493
1494 // The dirty cards region list is used to record a subset of regions
1495 // whose cards need clearing. The list if populated during the
1496 // remembered set scanning and drained during the card table
1497 // cleanup. Although the methods are reentrant, population/draining
1498 // phases must not overlap. For synchronization purposes the last
1499 // element on the list points to itself.
1500 HeapRegion* _dirty_cards_region_list;
1501 void push_dirty_cards_region(HeapRegion* hr);
1502 HeapRegion* pop_dirty_cards_region();
1503
1504 public:
1505 void stop_conc_gc_threads();
1506
1507 // <NEW PREDICTION>
1508
1509 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1510 void check_if_region_is_too_expensive(double predicted_time_ms);
1511 size_t pending_card_num();
1512 size_t max_pending_card_num();
1513 size_t cards_scanned();
1514
1515 // </NEW PREDICTION>
1516
1517 protected:
1518 size_t _max_heap_capacity;
1519 };
1520
1521 #define use_local_bitmaps 1
1522 #define verify_local_bitmaps 0
1523 #define oop_buffer_length 256
1524
1525 #ifndef PRODUCT
1526 class GCLabBitMap;
1527 class GCLabBitMapClosure: public BitMapClosure {
1528 private:
1529 ConcurrentMark* _cm;
1530 GCLabBitMap* _bitmap;
1531
1532 public:
1533 GCLabBitMapClosure(ConcurrentMark* cm,
1534 GCLabBitMap* bitmap) {
1535 _cm = cm;
1536 _bitmap = bitmap;
1537 }
1538
1539 virtual bool do_bit(size_t offset);
1540 };
1541 #endif // !PRODUCT
1542
1543 class GCLabBitMap: public BitMap {
1544 private:
1545 ConcurrentMark* _cm;
1546
1547 int _shifter;
1548 size_t _bitmap_word_covers_words;
1549
1550 // beginning of the heap
1551 HeapWord* _heap_start;
1552
1553 // this is the actual start of the GCLab
1554 HeapWord* _real_start_word;
1555
1556 // this is the actual end of the GCLab
1557 HeapWord* _real_end_word;
1558
1559 // this is the first word, possibly located before the actual start
1560 // of the GCLab, that corresponds to the first bit of the bitmap
1561 HeapWord* _start_word;
1562
1563 // size of a GCLab in words
1564 size_t _gclab_word_size;
1565
1566 static int shifter() {
1567 return MinObjAlignment - 1;
1568 }
1569
1570 // how many heap words does a single bitmap word corresponds to?
1571 static size_t bitmap_word_covers_words() {
1572 return BitsPerWord << shifter();
1573 }
1574
1575 size_t gclab_word_size() const {
1576 return _gclab_word_size;
1577 }
1578
1579 // Calculates actual GCLab size in words
1580 size_t gclab_real_word_size() const {
1581 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1582 / BitsPerWord;
1583 }
1584
1585 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1586 size_t bits_in_bitmap = gclab_word_size >> shifter();
1587 // We are going to ensure that the beginning of a word in this
1588 // bitmap also corresponds to the beginning of a word in the
1589 // global marking bitmap. To handle the case where a GCLab
1590 // starts from the middle of the bitmap, we need to add enough
1591 // space (i.e. up to a bitmap word) to ensure that we have
1592 // enough bits in the bitmap.
1593 return bits_in_bitmap + BitsPerWord - 1;
1594 }
1595 public:
1596 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1597 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1598 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1599 _shifter(shifter()),
1600 _bitmap_word_covers_words(bitmap_word_covers_words()),
1601 _heap_start(heap_start),
1602 _gclab_word_size(gclab_word_size),
1603 _real_start_word(NULL),
1604 _real_end_word(NULL),
1605 _start_word(NULL)
1606 {
1607 guarantee( size_in_words() >= bitmap_size_in_words(),
1608 "just making sure");
1609 }
1610
1611 inline unsigned heapWordToOffset(HeapWord* addr) {
1612 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1613 assert(offset < size(), "offset should be within bounds");
1614 return offset;
1615 }
1616
1617 inline HeapWord* offsetToHeapWord(size_t offset) {
1618 HeapWord* addr = _start_word + (offset << _shifter);
1619 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1620 return addr;
1621 }
1622
1623 bool fields_well_formed() {
1624 bool ret1 = (_real_start_word == NULL) &&
1625 (_real_end_word == NULL) &&
1626 (_start_word == NULL);
1627 if (ret1)
1628 return true;
1629
1630 bool ret2 = _real_start_word >= _start_word &&
1631 _start_word < _real_end_word &&
1632 (_real_start_word + _gclab_word_size) == _real_end_word &&
1633 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1634 > _real_end_word;
1635 return ret2;
1636 }
1637
1638 inline bool mark(HeapWord* addr) {
1639 guarantee(use_local_bitmaps, "invariant");
1640 assert(fields_well_formed(), "invariant");
1641
1642 if (addr >= _real_start_word && addr < _real_end_word) {
1643 assert(!isMarked(addr), "should not have already been marked");
1644
1645 // first mark it on the bitmap
1646 at_put(heapWordToOffset(addr), true);
1647
1648 return true;
1649 } else {
1650 return false;
1651 }
1652 }
1653
1654 inline bool isMarked(HeapWord* addr) {
1655 guarantee(use_local_bitmaps, "invariant");
1656 assert(fields_well_formed(), "invariant");
1657
1658 return at(heapWordToOffset(addr));
1659 }
1660
1661 void set_buffer(HeapWord* start) {
1662 guarantee(use_local_bitmaps, "invariant");
1663 clear();
1664
1665 assert(start != NULL, "invariant");
1666 _real_start_word = start;
1667 _real_end_word = start + _gclab_word_size;
1668
1669 size_t diff =
1670 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1671 _start_word = start - diff;
1672
1673 assert(fields_well_formed(), "invariant");
1674 }
1675
1676 #ifndef PRODUCT
1677 void verify() {
1678 // verify that the marks have been propagated
1679 GCLabBitMapClosure cl(_cm, this);
1680 iterate(&cl);
1681 }
1682 #endif // PRODUCT
1683
1684 void retire() {
1685 guarantee(use_local_bitmaps, "invariant");
1686 assert(fields_well_formed(), "invariant");
1687
1688 if (_start_word != NULL) {
1689 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1690
1691 // this means that the bitmap was set up for the GCLab
1692 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1693
1694 mark_bitmap->mostly_disjoint_range_union(this,
1695 0, // always start from the start of the bitmap
1696 _start_word,
1697 gclab_real_word_size());
1698 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1699
1700 #ifndef PRODUCT
1701 if (use_local_bitmaps && verify_local_bitmaps)
1702 verify();
1703 #endif // PRODUCT
1704 } else {
1705 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1706 }
1707 }
1708
1709 size_t bitmap_size_in_words() const {
1710 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1711 }
1712
1713 };
1714
1715 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1716 private:
1717 bool _retired;
1718 bool _should_mark_objects;
1719 GCLabBitMap _bitmap;
1720
1721 public:
1722 G1ParGCAllocBuffer(size_t gclab_word_size);
1723
1724 inline bool mark(HeapWord* addr) {
1725 guarantee(use_local_bitmaps, "invariant");
1726 assert(_should_mark_objects, "invariant");
1727 return _bitmap.mark(addr);
1728 }
1729
1730 inline void set_buf(HeapWord* buf) {
1731 if (use_local_bitmaps && _should_mark_objects) {
1732 _bitmap.set_buffer(buf);
1733 }
1734 ParGCAllocBuffer::set_buf(buf);
1735 _retired = false;
1736 }
1737
1738 inline void retire(bool end_of_gc, bool retain) {
1739 if (_retired)
1740 return;
1741 if (use_local_bitmaps && _should_mark_objects) {
1742 _bitmap.retire();
1743 }
1744 ParGCAllocBuffer::retire(end_of_gc, retain);
1745 _retired = true;
1746 }
1747 };
1748
1749 class G1ParScanThreadState : public StackObj {
1750 protected:
1751 G1CollectedHeap* _g1h;
1752 RefToScanQueue* _refs;
1753 DirtyCardQueue _dcq;
1754 CardTableModRefBS* _ct_bs;
1755 G1RemSet* _g1_rem;
1756
1757 G1ParGCAllocBuffer _surviving_alloc_buffer;
1758 G1ParGCAllocBuffer _tenured_alloc_buffer;
1759 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1760 ageTable _age_table;
1761
1762 size_t _alloc_buffer_waste;
1763 size_t _undo_waste;
1764
1765 OopsInHeapRegionClosure* _evac_failure_cl;
1766 G1ParScanHeapEvacClosure* _evac_cl;
1767 G1ParScanPartialArrayClosure* _partial_scan_cl;
1768
1769 int _hash_seed;
1770 int _queue_num;
1771
1772 size_t _term_attempts;
1773
1774 double _start;
1775 double _start_strong_roots;
1776 double _strong_roots_time;
1777 double _start_term;
1778 double _term_time;
1779
1780 // Map from young-age-index (0 == not young, 1 is youngest) to
1781 // surviving words. base is what we get back from the malloc call
1782 size_t* _surviving_young_words_base;
1783 // this points into the array, as we use the first few entries for padding
1784 size_t* _surviving_young_words;
1785
1786 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1787
1788 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1789
1790 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1791
1792 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1793 CardTableModRefBS* ctbs() { return _ct_bs; }
1794
1795 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1796 if (!from->is_survivor()) {
1797 _g1_rem->par_write_ref(from, p, tid);
1798 }
1799 }
1800
1801 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1802 // If the new value of the field points to the same region or
1803 // is the to-space, we don't need to include it in the Rset updates.
1804 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1805 size_t card_index = ctbs()->index_for(p);
1806 // If the card hasn't been added to the buffer, do it.
1807 if (ctbs()->mark_card_deferred(card_index)) {
1808 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1809 }
1810 }
1811 }
1812
1813 public:
1814 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1815
1816 ~G1ParScanThreadState() {
1817 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1818 }
1819
1820 RefToScanQueue* refs() { return _refs; }
1821 ageTable* age_table() { return &_age_table; }
1822
1823 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1824 return _alloc_buffers[purpose];
1825 }
1826
1827 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1828 size_t undo_waste() const { return _undo_waste; }
1829
1830 #ifdef ASSERT
1831 bool verify_ref(narrowOop* ref) const;
1832 bool verify_ref(oop* ref) const;
1833 bool verify_task(StarTask ref) const;
1834 #endif // ASSERT
1835
1836 template <class T> void push_on_queue(T* ref) {
1837 assert(verify_ref(ref), "sanity");
1838 refs()->push(ref);
1839 }
1840
1841 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1842 if (G1DeferredRSUpdate) {
1843 deferred_rs_update(from, p, tid);
1844 } else {
1845 immediate_rs_update(from, p, tid);
1846 }
1847 }
1848
1849 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1850
1851 HeapWord* obj = NULL;
1852 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1853 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1854 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1855 assert(gclab_word_size == alloc_buf->word_sz(),
1856 "dynamic resizing is not supported");
1857 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1858 alloc_buf->retire(false, false);
1859
1860 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1861 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1862 // Otherwise.
1863 alloc_buf->set_buf(buf);
1864
1865 obj = alloc_buf->allocate(word_sz);
1866 assert(obj != NULL, "buffer was definitely big enough...");
1867 } else {
1868 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1869 }
1870 return obj;
1871 }
1872
1873 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1874 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1875 if (obj != NULL) return obj;
1876 return allocate_slow(purpose, word_sz);
1877 }
1878
1879 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1880 if (alloc_buffer(purpose)->contains(obj)) {
1881 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1882 "should contain whole object");
1883 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1884 } else {
1885 CollectedHeap::fill_with_object(obj, word_sz);
1886 add_to_undo_waste(word_sz);
1887 }
1888 }
1889
1890 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1891 _evac_failure_cl = evac_failure_cl;
1892 }
1893 OopsInHeapRegionClosure* evac_failure_closure() {
1894 return _evac_failure_cl;
1895 }
1896
1897 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1898 _evac_cl = evac_cl;
1899 }
1900
1901 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1902 _partial_scan_cl = partial_scan_cl;
1903 }
1904
1905 int* hash_seed() { return &_hash_seed; }
1906 int queue_num() { return _queue_num; }
1907
1908 size_t term_attempts() const { return _term_attempts; }
1909 void note_term_attempt() { _term_attempts++; }
1910
1911 void start_strong_roots() {
1912 _start_strong_roots = os::elapsedTime();
1913 }
1914 void end_strong_roots() {
1915 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1916 }
1917 double strong_roots_time() const { return _strong_roots_time; }
1918
1919 void start_term_time() {
1920 note_term_attempt();
1921 _start_term = os::elapsedTime();
1922 }
1923 void end_term_time() {
1924 _term_time += (os::elapsedTime() - _start_term);
1925 }
1926 double term_time() const { return _term_time; }
1927
1928 double elapsed_time() const {
1929 return os::elapsedTime() - _start;
1930 }
1931
1932 static void
1933 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1934 void
1935 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1936
1937 size_t* surviving_young_words() {
1938 // We add on to hide entry 0 which accumulates surviving words for
1939 // age -1 regions (i.e. non-young ones)
1940 return _surviving_young_words;
1941 }
1942
1943 void retire_alloc_buffers() {
1944 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1945 size_t waste = _alloc_buffers[ap]->words_remaining();
1946 add_to_alloc_buffer_waste(waste);
1947 _alloc_buffers[ap]->retire(true, false);
1948 }
1949 }
1950
1951 template <class T> void deal_with_reference(T* ref_to_scan) {
1952 if (has_partial_array_mask(ref_to_scan)) {
1953 _partial_scan_cl->do_oop_nv(ref_to_scan);
1954 } else {
1955 // Note: we can use "raw" versions of "region_containing" because
1956 // "obj_to_scan" is definitely in the heap, and is not in a
1957 // humongous region.
1958 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1959 _evac_cl->set_region(r);
1960 _evac_cl->do_oop_nv(ref_to_scan);
1961 }
1962 }
1963
1964 void deal_with_reference(StarTask ref) {
1965 assert(verify_task(ref), "sanity");
1966 if (ref.is_narrow()) {
1967 deal_with_reference((narrowOop*)ref);
1968 } else {
1969 deal_with_reference((oop*)ref);
1970 }
1971 }
1972
1973 public:
1974 void trim_queue();
1975 };
1976
1977 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP