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
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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20 * or visit www.oracle.com if you need additional information or have any
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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 RefineCardTableEntryClosure;
159 class G1CollectedHeap : public SharedHeap {
160 friend class VM_G1CollectForAllocation;
161 friend class VM_GenCollectForPermanentAllocation;
162 friend class VM_G1CollectFull;
163 friend class VM_G1IncCollectionPause;
164 friend class VMStructs;
165 friend class MutatorAllocRegion;
166
167 // Closures used in implementation.
168 friend class G1ParCopyHelper;
169 friend class G1IsAliveClosure;
170 friend class G1EvacuateFollowersClosure;
171 friend class G1ParScanThreadState;
172 friend class G1ParScanClosureSuper;
173 friend class G1ParEvacuateFollowersClosure;
174 friend class G1ParTask;
175 friend class G1FreeGarbageRegionClosure;
176 friend class RefineCardTableEntryClosure;
177 friend class G1PrepareCompactClosure;
178 friend class RegionSorter;
179 friend class RegionResetter;
180 friend class CountRCClosure;
181 friend class EvacPopObjClosure;
182 friend class G1ParCleanupCTTask;
183
184 // Other related classes.
185 friend class G1MarkSweep;
186
187 private:
188 // The one and only G1CollectedHeap, so static functions can find it.
189 static G1CollectedHeap* _g1h;
190
191 static size_t _humongous_object_threshold_in_words;
192
193 // Storage for the G1 heap (excludes the permanent generation).
194 VirtualSpace _g1_storage;
195 MemRegion _g1_reserved;
196
197 // The part of _g1_storage that is currently committed.
198 MemRegion _g1_committed;
199
200 // The master free list. It will satisfy all new region allocations.
201 MasterFreeRegionList _free_list;
202
203 // The secondary free list which contains regions that have been
204 // freed up during the cleanup process. This will be appended to the
205 // master free list when appropriate.
206 SecondaryFreeRegionList _secondary_free_list;
207
208 // It keeps track of the humongous regions.
209 MasterHumongousRegionSet _humongous_set;
210
211 // The number of regions we could create by expansion.
212 size_t _expansion_regions;
213
214 // The block offset table for the G1 heap.
215 G1BlockOffsetSharedArray* _bot_shared;
216
217 // Move all of the regions off the free lists, then rebuild those free
218 // lists, before and after full GC.
219 void tear_down_region_lists();
220 void rebuild_region_lists();
221
222 // The sequence of all heap regions in the heap.
223 HeapRegionSeq _hrs;
224
225 // Alloc region used to satisfy mutator allocation requests.
226 MutatorAllocRegion _mutator_alloc_region;
227
228 // It resets the mutator alloc region before new allocations can take place.
229 void init_mutator_alloc_region();
230
231 // It releases the mutator alloc region.
232 void release_mutator_alloc_region();
233
234 void abandon_gc_alloc_regions();
235
236 // The to-space memory regions into which objects are being copied during
237 // a GC.
238 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
239 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
240 // These are the regions, one per GCAllocPurpose, that are half-full
241 // at the end of a collection and that we want to reuse during the
242 // next collection.
243 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
244 // This specifies whether we will keep the last half-full region at
245 // the end of a collection so that it can be reused during the next
246 // collection (this is specified per GCAllocPurpose)
247 bool _retain_gc_alloc_region[GCAllocPurposeCount];
248
249 // A list of the regions that have been set to be alloc regions in the
250 // current collection.
251 HeapRegion* _gc_alloc_region_list;
252
253 // Helper for monitoring and management support.
254 G1MonitoringSupport* _g1mm;
255
256 // Determines PLAB size for a particular allocation purpose.
257 static size_t desired_plab_sz(GCAllocPurpose purpose);
258
259 // When called by par thread, requires the FreeList_lock to be held.
260 void push_gc_alloc_region(HeapRegion* hr);
261
262 // This should only be called single-threaded. Undeclares all GC alloc
263 // regions.
264 void forget_alloc_region_list();
265
266 // Should be used to set an alloc region, because there's other
267 // associated bookkeeping.
268 void set_gc_alloc_region(int purpose, HeapRegion* r);
269
270 // Check well-formedness of alloc region list.
271 bool check_gc_alloc_regions();
272
273 // Outside of GC pauses, the number of bytes used in all regions other
274 // than the current allocation region.
275 size_t _summary_bytes_used;
276
277 // This is used for a quick test on whether a reference points into
278 // the collection set or not. Basically, we have an array, with one
279 // byte per region, and that byte denotes whether the corresponding
280 // region is in the collection set or not. The entry corresponding
281 // the bottom of the heap, i.e., region 0, is pointed to by
282 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
283 // biased so that it actually points to address 0 of the address
284 // space, to make the test as fast as possible (we can simply shift
285 // the address to address into it, instead of having to subtract the
286 // bottom of the heap from the address before shifting it; basically
287 // it works in the same way the card table works).
288 bool* _in_cset_fast_test;
289
290 // The allocated array used for the fast test on whether a reference
291 // points into the collection set or not. This field is also used to
292 // free the array.
293 bool* _in_cset_fast_test_base;
294
295 // The length of the _in_cset_fast_test_base array.
296 size_t _in_cset_fast_test_length;
297
298 volatile unsigned _gc_time_stamp;
299
300 size_t* _surviving_young_words;
301
302 G1HRPrinter _hr_printer;
303
304 void setup_surviving_young_words();
305 void update_surviving_young_words(size_t* surv_young_words);
306 void cleanup_surviving_young_words();
307
308 // It decides whether an explicit GC should start a concurrent cycle
309 // instead of doing a STW GC. Currently, a concurrent cycle is
310 // explicitly started if:
311 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
312 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
313 bool should_do_concurrent_full_gc(GCCause::Cause cause);
314
315 // Keeps track of how many "full collections" (i.e., Full GCs or
316 // concurrent cycles) we have completed. The number of them we have
317 // started is maintained in _total_full_collections in CollectedHeap.
318 volatile unsigned int _full_collections_completed;
319
320 // This is a non-product method that is helpful for testing. It is
321 // called at the end of a GC and artificially expands the heap by
322 // allocating a number of dead regions. This way we can induce very
323 // frequent marking cycles and stress the cleanup / concurrent
324 // cleanup code more (as all the regions that will be allocated by
325 // this method will be found dead by the marking cycle).
326 void allocate_dummy_regions() PRODUCT_RETURN;
327
328 // These are macros so that, if the assert fires, we get the correct
329 // line number, file, etc.
330
331 #define heap_locking_asserts_err_msg(_extra_message_) \
332 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
333 (_extra_message_), \
334 BOOL_TO_STR(Heap_lock->owned_by_self()), \
335 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
336 BOOL_TO_STR(Thread::current()->is_VM_thread()))
337
338 #define assert_heap_locked() \
339 do { \
340 assert(Heap_lock->owned_by_self(), \
341 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
342 } while (0)
343
344 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
345 do { \
346 assert(Heap_lock->owned_by_self() || \
347 (SafepointSynchronize::is_at_safepoint() && \
348 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
349 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
350 "should be at a safepoint")); \
351 } while (0)
352
353 #define assert_heap_locked_and_not_at_safepoint() \
354 do { \
355 assert(Heap_lock->owned_by_self() && \
356 !SafepointSynchronize::is_at_safepoint(), \
357 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
358 "should not be at a safepoint")); \
359 } while (0)
360
361 #define assert_heap_not_locked() \
362 do { \
363 assert(!Heap_lock->owned_by_self(), \
364 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
365 } while (0)
366
367 #define assert_heap_not_locked_and_not_at_safepoint() \
368 do { \
369 assert(!Heap_lock->owned_by_self() && \
370 !SafepointSynchronize::is_at_safepoint(), \
371 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
372 "should not be at a safepoint")); \
373 } while (0)
374
375 #define assert_at_safepoint(_should_be_vm_thread_) \
376 do { \
377 assert(SafepointSynchronize::is_at_safepoint() && \
378 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
379 heap_locking_asserts_err_msg("should be at a safepoint")); \
380 } while (0)
381
382 #define assert_not_at_safepoint() \
383 do { \
384 assert(!SafepointSynchronize::is_at_safepoint(), \
385 heap_locking_asserts_err_msg("should not be at a safepoint")); \
386 } while (0)
387
388 protected:
389
390 // Returns "true" iff none of the gc alloc regions have any allocations
391 // since the last call to "save_marks".
392 bool all_alloc_regions_no_allocs_since_save_marks();
393 // Perform finalization stuff on all allocation regions.
394 void retire_all_alloc_regions();
395
396 // The young region list.
397 YoungList* _young_list;
398
399 // The current policy object for the collector.
400 G1CollectorPolicy* _g1_policy;
401
402 // This is the second level of trying to allocate a new region. If
403 // new_region() didn't find a region on the free_list, this call will
404 // check whether there's anything available on the
405 // secondary_free_list and/or wait for more regions to appear on
406 // that list, if _free_regions_coming is set.
407 HeapRegion* new_region_try_secondary_free_list();
408
409 // Try to allocate a single non-humongous HeapRegion sufficient for
410 // an allocation of the given word_size. If do_expand is true,
411 // attempt to expand the heap if necessary to satisfy the allocation
412 // request.
413 HeapRegion* new_region(size_t word_size, bool do_expand);
414
415 // Try to allocate a new region to be used for allocation by
416 // a GC thread. It will try to expand the heap if no region is
417 // available.
418 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
419
420 // Attempt to satisfy a humongous allocation request of the given
421 // size by finding a contiguous set of free regions of num_regions
422 // length and remove them from the master free list. Return the
423 // index of the first region or G1_NULL_HRS_INDEX if the search
424 // was unsuccessful.
425 size_t humongous_obj_allocate_find_first(size_t num_regions,
426 size_t word_size);
427
428 // Initialize a contiguous set of free regions of length num_regions
429 // and starting at index first so that they appear as a single
430 // humongous region.
431 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
432 size_t num_regions,
433 size_t word_size);
434
435 // Attempt to allocate a humongous object of the given size. Return
436 // NULL if unsuccessful.
437 HeapWord* humongous_obj_allocate(size_t word_size);
438
439 // The following two methods, allocate_new_tlab() and
440 // mem_allocate(), are the two main entry points from the runtime
441 // into the G1's allocation routines. They have the following
442 // assumptions:
443 //
444 // * They should both be called outside safepoints.
445 //
446 // * They should both be called without holding the Heap_lock.
447 //
448 // * All allocation requests for new TLABs should go to
449 // allocate_new_tlab().
450 //
451 // * All non-TLAB allocation requests should go to mem_allocate().
452 //
453 // * If either call cannot satisfy the allocation request using the
454 // current allocating region, they will try to get a new one. If
455 // this fails, they will attempt to do an evacuation pause and
456 // retry the allocation.
457 //
458 // * If all allocation attempts fail, even after trying to schedule
459 // an evacuation pause, allocate_new_tlab() will return NULL,
460 // whereas mem_allocate() will attempt a heap expansion and/or
461 // schedule a Full GC.
462 //
463 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
464 // should never be called with word_size being humongous. All
465 // humongous allocation requests should go to mem_allocate() which
466 // will satisfy them with a special path.
467
468 virtual HeapWord* allocate_new_tlab(size_t word_size);
469
470 virtual HeapWord* mem_allocate(size_t word_size,
471 bool* gc_overhead_limit_was_exceeded);
472
473 // The following three methods take a gc_count_before_ret
474 // parameter which is used to return the GC count if the method
475 // returns NULL. Given that we are required to read the GC count
476 // while holding the Heap_lock, and these paths will take the
477 // Heap_lock at some point, it's easier to get them to read the GC
478 // count while holding the Heap_lock before they return NULL instead
479 // of the caller (namely: mem_allocate()) having to also take the
480 // Heap_lock just to read the GC count.
481
482 // First-level mutator allocation attempt: try to allocate out of
483 // the mutator alloc region without taking the Heap_lock. This
484 // should only be used for non-humongous allocations.
485 inline HeapWord* attempt_allocation(size_t word_size,
486 unsigned int* gc_count_before_ret);
487
488 // Second-level mutator allocation attempt: take the Heap_lock and
489 // retry the allocation attempt, potentially scheduling a GC
490 // pause. This should only be used for non-humongous allocations.
491 HeapWord* attempt_allocation_slow(size_t word_size,
492 unsigned int* gc_count_before_ret);
493
494 // Takes the Heap_lock and attempts a humongous allocation. It can
495 // potentially schedule a GC pause.
496 HeapWord* attempt_allocation_humongous(size_t word_size,
497 unsigned int* gc_count_before_ret);
498
499 // Allocation attempt that should be called during safepoints (e.g.,
500 // at the end of a successful GC). expect_null_mutator_alloc_region
501 // specifies whether the mutator alloc region is expected to be NULL
502 // or not.
503 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
504 bool expect_null_mutator_alloc_region);
505
506 // It dirties the cards that cover the block so that so that the post
507 // write barrier never queues anything when updating objects on this
508 // block. It is assumed (and in fact we assert) that the block
509 // belongs to a young region.
510 inline void dirty_young_block(HeapWord* start, size_t word_size);
511
512 // Allocate blocks during garbage collection. Will ensure an
513 // allocation region, either by picking one or expanding the
514 // heap, and then allocate a block of the given size. The block
515 // may not be a humongous - it must fit into a single heap region.
516 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
517
518 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
519 HeapRegion* alloc_region,
520 bool par,
521 size_t word_size);
522
523 // Ensure that no further allocations can happen in "r", bearing in mind
524 // that parallel threads might be attempting allocations.
525 void par_allocate_remaining_space(HeapRegion* r);
526
527 // Retires an allocation region when it is full or at the end of a
528 // GC pause.
529 void retire_alloc_region(HeapRegion* alloc_region, bool par);
530
531 // These two methods are the "callbacks" from the G1AllocRegion class.
532
533 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
534 void retire_mutator_alloc_region(HeapRegion* alloc_region,
535 size_t allocated_bytes);
536
537 // - if explicit_gc is true, the GC is for a System.gc() or a heap
538 // inspection request and should collect the entire heap
539 // - if clear_all_soft_refs is true, all soft references should be
540 // cleared during the GC
541 // - if explicit_gc is false, word_size describes the allocation that
542 // the GC should attempt (at least) to satisfy
543 // - it returns false if it is unable to do the collection due to the
544 // GC locker being active, true otherwise
545 bool do_collection(bool explicit_gc,
546 bool clear_all_soft_refs,
547 size_t word_size);
548
549 // Callback from VM_G1CollectFull operation.
550 // Perform a full collection.
551 void do_full_collection(bool clear_all_soft_refs);
552
553 // Resize the heap if necessary after a full collection. If this is
554 // after a collect-for allocation, "word_size" is the allocation size,
555 // and will be considered part of the used portion of the heap.
556 void resize_if_necessary_after_full_collection(size_t word_size);
557
558 // Callback from VM_G1CollectForAllocation operation.
559 // This function does everything necessary/possible to satisfy a
560 // failed allocation request (including collection, expansion, etc.)
561 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
562
563 // Attempting to expand the heap sufficiently
564 // to support an allocation of the given "word_size". If
565 // successful, perform the allocation and return the address of the
566 // allocated block, or else "NULL".
567 HeapWord* expand_and_allocate(size_t word_size);
568
569 public:
570
571 G1MonitoringSupport* g1mm() { return _g1mm; }
572
573 // Expand the garbage-first heap by at least the given size (in bytes!).
574 // Returns true if the heap was expanded by the requested amount;
575 // false otherwise.
576 // (Rounds up to a HeapRegion boundary.)
577 bool expand(size_t expand_bytes);
578
579 // Do anything common to GC's.
580 virtual void gc_prologue(bool full);
581 virtual void gc_epilogue(bool full);
582
583 // We register a region with the fast "in collection set" test. We
584 // simply set to true the array slot corresponding to this region.
585 void register_region_with_in_cset_fast_test(HeapRegion* r) {
586 assert(_in_cset_fast_test_base != NULL, "sanity");
587 assert(r->in_collection_set(), "invariant");
588 size_t index = r->hrs_index();
589 assert(index < _in_cset_fast_test_length, "invariant");
590 assert(!_in_cset_fast_test_base[index], "invariant");
591 _in_cset_fast_test_base[index] = true;
592 }
593
594 // This is a fast test on whether a reference points into the
595 // collection set or not. It does not assume that the reference
596 // points into the heap; if it doesn't, it will return false.
597 bool in_cset_fast_test(oop obj) {
598 assert(_in_cset_fast_test != NULL, "sanity");
599 if (_g1_committed.contains((HeapWord*) obj)) {
600 // no need to subtract the bottom of the heap from obj,
601 // _in_cset_fast_test is biased
602 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
603 bool ret = _in_cset_fast_test[index];
604 // let's make sure the result is consistent with what the slower
605 // test returns
606 assert( ret || !obj_in_cs(obj), "sanity");
607 assert(!ret || obj_in_cs(obj), "sanity");
608 return ret;
609 } else {
610 return false;
611 }
612 }
613
614 void clear_cset_fast_test() {
615 assert(_in_cset_fast_test_base != NULL, "sanity");
616 memset(_in_cset_fast_test_base, false,
617 _in_cset_fast_test_length * sizeof(bool));
618 }
619
620 // This is called at the end of either a concurrent cycle or a Full
621 // GC to update the number of full collections completed. Those two
622 // can happen in a nested fashion, i.e., we start a concurrent
623 // cycle, a Full GC happens half-way through it which ends first,
624 // and then the cycle notices that a Full GC happened and ends
625 // too. The concurrent parameter is a boolean to help us do a bit
626 // tighter consistency checking in the method. If concurrent is
627 // false, the caller is the inner caller in the nesting (i.e., the
628 // Full GC). If concurrent is true, the caller is the outer caller
629 // in this nesting (i.e., the concurrent cycle). Further nesting is
630 // not currently supported. The end of the this call also notifies
631 // the FullGCCount_lock in case a Java thread is waiting for a full
632 // GC to happen (e.g., it called System.gc() with
633 // +ExplicitGCInvokesConcurrent).
634 void increment_full_collections_completed(bool concurrent);
635
636 unsigned int full_collections_completed() {
637 return _full_collections_completed;
638 }
639
640 G1HRPrinter* hr_printer() { return &_hr_printer; }
641
642 protected:
643
644 // Shrink the garbage-first heap by at most the given size (in bytes!).
645 // (Rounds down to a HeapRegion boundary.)
646 virtual void shrink(size_t expand_bytes);
647 void shrink_helper(size_t expand_bytes);
648
649 #if TASKQUEUE_STATS
650 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
651 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
652 void reset_taskqueue_stats();
653 #endif // TASKQUEUE_STATS
654
655 // Schedule the VM operation that will do an evacuation pause to
656 // satisfy an allocation request of word_size. *succeeded will
657 // return whether the VM operation was successful (it did do an
658 // evacuation pause) or not (another thread beat us to it or the GC
659 // locker was active). Given that we should not be holding the
660 // Heap_lock when we enter this method, we will pass the
661 // gc_count_before (i.e., total_collections()) as a parameter since
662 // it has to be read while holding the Heap_lock. Currently, both
663 // methods that call do_collection_pause() release the Heap_lock
664 // before the call, so it's easy to read gc_count_before just before.
665 HeapWord* do_collection_pause(size_t word_size,
666 unsigned int gc_count_before,
667 bool* succeeded);
668
669 // The guts of the incremental collection pause, executed by the vm
670 // thread. It returns false if it is unable to do the collection due
671 // to the GC locker being active, true otherwise
672 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
673
674 // Actually do the work of evacuating the collection set.
675 void evacuate_collection_set();
676
677 // The g1 remembered set of the heap.
678 G1RemSet* _g1_rem_set;
679 // And it's mod ref barrier set, used to track updates for the above.
680 ModRefBarrierSet* _mr_bs;
681
682 // A set of cards that cover the objects for which the Rsets should be updated
683 // concurrently after the collection.
684 DirtyCardQueueSet _dirty_card_queue_set;
685
686 // The Heap Region Rem Set Iterator.
687 HeapRegionRemSetIterator** _rem_set_iterator;
688
689 // The closure used to refine a single card.
690 RefineCardTableEntryClosure* _refine_cte_cl;
691
692 // A function to check the consistency of dirty card logs.
693 void check_ct_logs_at_safepoint();
694
695 // A DirtyCardQueueSet that is used to hold cards that contain
696 // references into the current collection set. This is used to
697 // update the remembered sets of the regions in the collection
698 // set in the event of an evacuation failure.
699 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
700
701 // After a collection pause, make the regions in the CS into free
702 // regions.
703 void free_collection_set(HeapRegion* cs_head);
704
705 // Abandon the current collection set without recording policy
706 // statistics or updating free lists.
707 void abandon_collection_set(HeapRegion* cs_head);
708
709 // Applies "scan_non_heap_roots" to roots outside the heap,
710 // "scan_rs" to roots inside the heap (having done "set_region" to
711 // indicate the region in which the root resides), and does "scan_perm"
712 // (setting the generation to the perm generation.) If "scan_rs" is
713 // NULL, then this step is skipped. The "worker_i"
714 // param is for use with parallel roots processing, and should be
715 // the "i" of the calling parallel worker thread's work(i) function.
716 // In the sequential case this param will be ignored.
717 void g1_process_strong_roots(bool collecting_perm_gen,
718 SharedHeap::ScanningOption so,
719 OopClosure* scan_non_heap_roots,
720 OopsInHeapRegionClosure* scan_rs,
721 OopsInGenClosure* scan_perm,
722 int worker_i);
723
724 // Apply "blk" to all the weak roots of the system. These include
725 // JNI weak roots, the code cache, system dictionary, symbol table,
726 // string table, and referents of reachable weak refs.
727 void g1_process_weak_roots(OopClosure* root_closure,
728 OopClosure* non_root_closure);
729
730 // Invoke "save_marks" on all heap regions.
731 void save_marks();
732
733 // Frees a non-humongous region by initializing its contents and
734 // adding it to the free list that's passed as a parameter (this is
735 // usually a local list which will be appended to the master free
736 // list later). The used bytes of freed regions are accumulated in
737 // pre_used. If par is true, the region's RSet will not be freed
738 // up. The assumption is that this will be done later.
739 void free_region(HeapRegion* hr,
740 size_t* pre_used,
741 FreeRegionList* free_list,
742 bool par);
743
744 // Frees a humongous region by collapsing it into individual regions
745 // and calling free_region() for each of them. The freed regions
746 // will be added to the free list that's passed as a parameter (this
747 // is usually a local list which will be appended to the master free
748 // list later). The used bytes of freed regions are accumulated in
749 // pre_used. If par is true, the region's RSet will not be freed
750 // up. The assumption is that this will be done later.
751 void free_humongous_region(HeapRegion* hr,
752 size_t* pre_used,
753 FreeRegionList* free_list,
754 HumongousRegionSet* humongous_proxy_set,
755 bool par);
756
757 // Notifies all the necessary spaces that the committed space has
758 // been updated (either expanded or shrunk). It should be called
759 // after _g1_storage is updated.
760 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
761
762 // The concurrent marker (and the thread it runs in.)
763 ConcurrentMark* _cm;
764 ConcurrentMarkThread* _cmThread;
765 bool _mark_in_progress;
766
767 // The concurrent refiner.
768 ConcurrentG1Refine* _cg1r;
769
770 // The parallel task queues
771 RefToScanQueueSet *_task_queues;
772
773 // True iff a evacuation has failed in the current collection.
774 bool _evacuation_failed;
775
776 // Set the attribute indicating whether evacuation has failed in the
777 // current collection.
778 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
779
780 // Failed evacuations cause some logical from-space objects to have
781 // forwarding pointers to themselves. Reset them.
782 void remove_self_forwarding_pointers();
783
784 // When one is non-null, so is the other. Together, they each pair is
785 // an object with a preserved mark, and its mark value.
786 GrowableArray<oop>* _objs_with_preserved_marks;
787 GrowableArray<markOop>* _preserved_marks_of_objs;
788
789 // Preserve the mark of "obj", if necessary, in preparation for its mark
790 // word being overwritten with a self-forwarding-pointer.
791 void preserve_mark_if_necessary(oop obj, markOop m);
792
793 // The stack of evac-failure objects left to be scanned.
794 GrowableArray<oop>* _evac_failure_scan_stack;
795 // The closure to apply to evac-failure objects.
796
797 OopsInHeapRegionClosure* _evac_failure_closure;
798 // Set the field above.
799 void
800 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
801 _evac_failure_closure = evac_failure_closure;
802 }
803
804 // Push "obj" on the scan stack.
805 void push_on_evac_failure_scan_stack(oop obj);
806 // Process scan stack entries until the stack is empty.
807 void drain_evac_failure_scan_stack();
808 // True iff an invocation of "drain_scan_stack" is in progress; to
809 // prevent unnecessary recursion.
810 bool _drain_in_progress;
811
812 // Do any necessary initialization for evacuation-failure handling.
813 // "cl" is the closure that will be used to process evac-failure
814 // objects.
815 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
816 // Do any necessary cleanup for evacuation-failure handling data
817 // structures.
818 void finalize_for_evac_failure();
819
820 // An attempt to evacuate "obj" has failed; take necessary steps.
821 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
822 void handle_evacuation_failure_common(oop obj, markOop m);
823
824 // Ensure that the relevant gc_alloc regions are set.
825 void get_gc_alloc_regions();
826 // We're done with GC alloc regions. We are going to tear down the
827 // gc alloc list and remove the gc alloc tag from all the regions on
828 // that list. However, we will also retain the last (i.e., the one
829 // that is half-full) GC alloc region, per GCAllocPurpose, for
830 // possible reuse during the next collection, provided
831 // _retain_gc_alloc_region[] indicates that it should be the
832 // case. Said regions are kept in the _retained_gc_alloc_regions[]
833 // array. If the parameter totally is set, we will not retain any
834 // regions, irrespective of what _retain_gc_alloc_region[]
835 // indicates.
836 void release_gc_alloc_regions(bool totally);
837 #ifndef PRODUCT
838 // Useful for debugging.
839 void print_gc_alloc_regions();
840 #endif // !PRODUCT
841
842 // Instance of the concurrent mark is_alive closure for embedding
843 // into the reference processor as the is_alive_non_header. This
844 // prevents unnecessary additions to the discovered lists during
845 // concurrent discovery.
846 G1CMIsAliveClosure _is_alive_closure;
847
848 // ("Weak") Reference processing support
849 ReferenceProcessor* _ref_processor;
850
851 enum G1H_process_strong_roots_tasks {
852 G1H_PS_mark_stack_oops_do,
853 G1H_PS_refProcessor_oops_do,
854 // Leave this one last.
855 G1H_PS_NumElements
856 };
857
858 SubTasksDone* _process_strong_tasks;
859
860 volatile bool _free_regions_coming;
861
862 public:
863
864 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
865
866 void set_refine_cte_cl_concurrency(bool concurrent);
867
868 RefToScanQueue *task_queue(int i) const;
869
870 // A set of cards where updates happened during the GC
871 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
872
873 // A DirtyCardQueueSet that is used to hold cards that contain
874 // references into the current collection set. This is used to
875 // update the remembered sets of the regions in the collection
876 // set in the event of an evacuation failure.
877 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
878 { return _into_cset_dirty_card_queue_set; }
879
880 // Create a G1CollectedHeap with the specified policy.
881 // Must call the initialize method afterwards.
882 // May not return if something goes wrong.
883 G1CollectedHeap(G1CollectorPolicy* policy);
884
885 // Initialize the G1CollectedHeap to have the initial and
886 // maximum sizes, permanent generation, and remembered and barrier sets
887 // specified by the policy object.
888 jint initialize();
889
890 virtual void ref_processing_init();
891
892 void set_par_threads(int t) {
893 SharedHeap::set_par_threads(t);
894 _process_strong_tasks->set_n_threads(t);
895 }
896
897 virtual CollectedHeap::Name kind() const {
898 return CollectedHeap::G1CollectedHeap;
899 }
900
901 // The current policy object for the collector.
902 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
903
904 // Adaptive size policy. No such thing for g1.
905 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
906
907 // The rem set and barrier set.
908 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
909 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
910
911 // The rem set iterator.
912 HeapRegionRemSetIterator* rem_set_iterator(int i) {
913 return _rem_set_iterator[i];
914 }
915
916 HeapRegionRemSetIterator* rem_set_iterator() {
917 return _rem_set_iterator[0];
918 }
919
920 unsigned get_gc_time_stamp() {
921 return _gc_time_stamp;
922 }
923
924 void reset_gc_time_stamp() {
925 _gc_time_stamp = 0;
926 OrderAccess::fence();
927 }
928
929 void increment_gc_time_stamp() {
930 ++_gc_time_stamp;
931 OrderAccess::fence();
932 }
933
934 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
935 DirtyCardQueue* into_cset_dcq,
936 bool concurrent, int worker_i);
937
938 // The shared block offset table array.
939 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
940
941 // Reference Processing accessor
942 ReferenceProcessor* ref_processor() { return _ref_processor; }
943
944 virtual size_t capacity() const;
945 virtual size_t used() const;
946 // This should be called when we're not holding the heap lock. The
947 // result might be a bit inaccurate.
948 size_t used_unlocked() const;
949 size_t recalculate_used() const;
950 #ifndef PRODUCT
951 size_t recalculate_used_regions() const;
952 #endif // PRODUCT
953
954 // These virtual functions do the actual allocation.
955 // Some heaps may offer a contiguous region for shared non-blocking
956 // allocation, via inlined code (by exporting the address of the top and
957 // end fields defining the extent of the contiguous allocation region.)
958 // But G1CollectedHeap doesn't yet support this.
959
960 // Return an estimate of the maximum allocation that could be performed
961 // without triggering any collection or expansion activity. In a
962 // generational collector, for example, this is probably the largest
963 // allocation that could be supported (without expansion) in the youngest
964 // generation. It is "unsafe" because no locks are taken; the result
965 // should be treated as an approximation, not a guarantee, for use in
966 // heuristic resizing decisions.
967 virtual size_t unsafe_max_alloc();
968
969 virtual bool is_maximal_no_gc() const {
970 return _g1_storage.uncommitted_size() == 0;
971 }
972
973 // The total number of regions in the heap.
974 size_t n_regions() { return _hrs.length(); }
975
976 // The max number of regions in the heap.
977 size_t max_regions() { return _hrs.max_length(); }
978
979 // The number of regions that are completely free.
980 size_t free_regions() { return _free_list.length(); }
981
982 // The number of regions that are not completely free.
983 size_t used_regions() { return n_regions() - free_regions(); }
984
985 // The number of regions available for "regular" expansion.
986 size_t expansion_regions() { return _expansion_regions; }
987
988 // Factory method for HeapRegion instances. It will return NULL if
989 // the allocation fails.
990 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
991
992 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
993 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
994 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
995 void verify_dirty_young_regions() PRODUCT_RETURN;
996
997 // verify_region_sets() performs verification over the region
998 // lists. It will be compiled in the product code to be used when
999 // necessary (i.e., during heap verification).
1000 void verify_region_sets();
1001
1002 // verify_region_sets_optional() is planted in the code for
1003 // list verification in non-product builds (and it can be enabled in
1004 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1005 #if HEAP_REGION_SET_FORCE_VERIFY
1006 void verify_region_sets_optional() {
1007 verify_region_sets();
1008 }
1009 #else // HEAP_REGION_SET_FORCE_VERIFY
1010 void verify_region_sets_optional() { }
1011 #endif // HEAP_REGION_SET_FORCE_VERIFY
1012
1013 #ifdef ASSERT
1014 bool is_on_master_free_list(HeapRegion* hr) {
1015 return hr->containing_set() == &_free_list;
1016 }
1017
1018 bool is_in_humongous_set(HeapRegion* hr) {
1019 return hr->containing_set() == &_humongous_set;
1020 }
1021 #endif // ASSERT
1022
1023 // Wrapper for the region list operations that can be called from
1024 // methods outside this class.
1025
1026 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1027 _secondary_free_list.add_as_tail(list);
1028 }
1029
1030 void append_secondary_free_list() {
1031 _free_list.add_as_head(&_secondary_free_list);
1032 }
1033
1034 void append_secondary_free_list_if_not_empty_with_lock() {
1035 // If the secondary free list looks empty there's no reason to
1036 // take the lock and then try to append it.
1037 if (!_secondary_free_list.is_empty()) {
1038 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1039 append_secondary_free_list();
1040 }
1041 }
1042
1043 void set_free_regions_coming();
1044 void reset_free_regions_coming();
1045 bool free_regions_coming() { return _free_regions_coming; }
1046 void wait_while_free_regions_coming();
1047
1048 // Perform a collection of the heap; intended for use in implementing
1049 // "System.gc". This probably implies as full a collection as the
1050 // "CollectedHeap" supports.
1051 virtual void collect(GCCause::Cause cause);
1052
1053 // The same as above but assume that the caller holds the Heap_lock.
1054 void collect_locked(GCCause::Cause cause);
1055
1056 // This interface assumes that it's being called by the
1057 // vm thread. It collects the heap assuming that the
1058 // heap lock is already held and that we are executing in
1059 // the context of the vm thread.
1060 virtual void collect_as_vm_thread(GCCause::Cause cause);
1061
1062 // True iff a evacuation has failed in the most-recent collection.
1063 bool evacuation_failed() { return _evacuation_failed; }
1064
1065 // It will free a region if it has allocated objects in it that are
1066 // all dead. It calls either free_region() or
1067 // free_humongous_region() depending on the type of the region that
1068 // is passed to it.
1069 void free_region_if_empty(HeapRegion* hr,
1070 size_t* pre_used,
1071 FreeRegionList* free_list,
1072 HumongousRegionSet* humongous_proxy_set,
1073 HRRSCleanupTask* hrrs_cleanup_task,
1074 bool par);
1075
1076 // It appends the free list to the master free list and updates the
1077 // master humongous list according to the contents of the proxy
1078 // list. It also adjusts the total used bytes according to pre_used
1079 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1080 void update_sets_after_freeing_regions(size_t pre_used,
1081 FreeRegionList* free_list,
1082 HumongousRegionSet* humongous_proxy_set,
1083 bool par);
1084
1085 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1086 virtual bool is_in(const void* p) const;
1087
1088 // Return "TRUE" iff the given object address is within the collection
1089 // set.
1090 inline bool obj_in_cs(oop obj);
1091
1092 // Return "TRUE" iff the given object address is in the reserved
1093 // region of g1 (excluding the permanent generation).
1094 bool is_in_g1_reserved(const void* p) const {
1095 return _g1_reserved.contains(p);
1096 }
1097
1098 // Returns a MemRegion that corresponds to the space that has been
1099 // reserved for the heap
1100 MemRegion g1_reserved() {
1101 return _g1_reserved;
1102 }
1103
1104 // Returns a MemRegion that corresponds to the space that has been
1105 // committed in the heap
1106 MemRegion g1_committed() {
1107 return _g1_committed;
1108 }
1109
1110 virtual bool is_in_closed_subset(const void* p) const;
1111
1112 // Dirty card table entries covering a list of young regions.
1113 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1114
1115 // This resets the card table to all zeros. It is used after
1116 // a collection pause which used the card table to claim cards.
1117 void cleanUpCardTable();
1118
1119 // Iteration functions.
1120
1121 // Iterate over all the ref-containing fields of all objects, calling
1122 // "cl.do_oop" on each.
1123 virtual void oop_iterate(OopClosure* cl) {
1124 oop_iterate(cl, true);
1125 }
1126 void oop_iterate(OopClosure* cl, bool do_perm);
1127
1128 // Same as above, restricted to a memory region.
1129 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1130 oop_iterate(mr, cl, true);
1131 }
1132 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1133
1134 // Iterate over all objects, calling "cl.do_object" on each.
1135 virtual void object_iterate(ObjectClosure* cl) {
1136 object_iterate(cl, true);
1137 }
1138 virtual void safe_object_iterate(ObjectClosure* cl) {
1139 object_iterate(cl, true);
1140 }
1141 void object_iterate(ObjectClosure* cl, bool do_perm);
1142
1143 // Iterate over all objects allocated since the last collection, calling
1144 // "cl.do_object" on each. The heap must have been initialized properly
1145 // to support this function, or else this call will fail.
1146 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1147
1148 // Iterate over all spaces in use in the heap, in ascending address order.
1149 virtual void space_iterate(SpaceClosure* cl);
1150
1151 // Iterate over heap regions, in address order, terminating the
1152 // iteration early if the "doHeapRegion" method returns "true".
1153 void heap_region_iterate(HeapRegionClosure* blk) const;
1154
1155 // Iterate over heap regions starting with r (or the first region if "r"
1156 // is NULL), in address order, terminating early if the "doHeapRegion"
1157 // method returns "true".
1158 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1159
1160 // Return the region with the given index. It assumes the index is valid.
1161 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1162
1163 // Divide the heap region sequence into "chunks" of some size (the number
1164 // of regions divided by the number of parallel threads times some
1165 // overpartition factor, currently 4). Assumes that this will be called
1166 // in parallel by ParallelGCThreads worker threads with discinct worker
1167 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1168 // calls will use the same "claim_value", and that that claim value is
1169 // different from the claim_value of any heap region before the start of
1170 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1171 // attempting to claim the first region in each chunk, and, if
1172 // successful, applying the closure to each region in the chunk (and
1173 // setting the claim value of the second and subsequent regions of the
1174 // chunk.) For now requires that "doHeapRegion" always returns "false",
1175 // i.e., that a closure never attempt to abort a traversal.
1176 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1177 int worker,
1178 jint claim_value);
1179
1180 // It resets all the region claim values to the default.
1181 void reset_heap_region_claim_values();
1182
1183 #ifdef ASSERT
1184 bool check_heap_region_claim_values(jint claim_value);
1185 #endif // ASSERT
1186
1187 // Iterate over the regions (if any) in the current collection set.
1188 void collection_set_iterate(HeapRegionClosure* blk);
1189
1190 // As above but starting from region r
1191 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1192
1193 // Returns the first (lowest address) compactible space in the heap.
1194 virtual CompactibleSpace* first_compactible_space();
1195
1196 // A CollectedHeap will contain some number of spaces. This finds the
1197 // space containing a given address, or else returns NULL.
1198 virtual Space* space_containing(const void* addr) const;
1199
1200 // A G1CollectedHeap will contain some number of heap regions. This
1201 // finds the region containing a given address, or else returns NULL.
1202 template <class T>
1203 inline HeapRegion* heap_region_containing(const T addr) const;
1204
1205 // Like the above, but requires "addr" to be in the heap (to avoid a
1206 // null-check), and unlike the above, may return an continuing humongous
1207 // region.
1208 template <class T>
1209 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1210
1211 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1212 // each address in the (reserved) heap is a member of exactly
1213 // one block. The defining characteristic of a block is that it is
1214 // possible to find its size, and thus to progress forward to the next
1215 // block. (Blocks may be of different sizes.) Thus, blocks may
1216 // represent Java objects, or they might be free blocks in a
1217 // free-list-based heap (or subheap), as long as the two kinds are
1218 // distinguishable and the size of each is determinable.
1219
1220 // Returns the address of the start of the "block" that contains the
1221 // address "addr". We say "blocks" instead of "object" since some heaps
1222 // may not pack objects densely; a chunk may either be an object or a
1223 // non-object.
1224 virtual HeapWord* block_start(const void* addr) const;
1225
1226 // Requires "addr" to be the start of a chunk, and returns its size.
1227 // "addr + size" is required to be the start of a new chunk, or the end
1228 // of the active area of the heap.
1229 virtual size_t block_size(const HeapWord* addr) const;
1230
1231 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1232 // the block is an object.
1233 virtual bool block_is_obj(const HeapWord* addr) const;
1234
1235 // Does this heap support heap inspection? (+PrintClassHistogram)
1236 virtual bool supports_heap_inspection() const { return true; }
1237
1238 // Section on thread-local allocation buffers (TLABs)
1239 // See CollectedHeap for semantics.
1240
1241 virtual bool supports_tlab_allocation() const;
1242 virtual size_t tlab_capacity(Thread* thr) const;
1243 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1244
1245 // Can a compiler initialize a new object without store barriers?
1246 // This permission only extends from the creation of a new object
1247 // via a TLAB up to the first subsequent safepoint. If such permission
1248 // is granted for this heap type, the compiler promises to call
1249 // defer_store_barrier() below on any slow path allocation of
1250 // a new object for which such initializing store barriers will
1251 // have been elided. G1, like CMS, allows this, but should be
1252 // ready to provide a compensating write barrier as necessary
1253 // if that storage came out of a non-young region. The efficiency
1254 // of this implementation depends crucially on being able to
1255 // answer very efficiently in constant time whether a piece of
1256 // storage in the heap comes from a young region or not.
1257 // See ReduceInitialCardMarks.
1258 virtual bool can_elide_tlab_store_barriers() const {
1259 // 6920090: Temporarily disabled, because of lingering
1260 // instabilities related to RICM with G1. In the
1261 // interim, the option ReduceInitialCardMarksForG1
1262 // below is left solely as a debugging device at least
1263 // until 6920109 fixes the instabilities.
1264 return ReduceInitialCardMarksForG1;
1265 }
1266
1267 virtual bool card_mark_must_follow_store() const {
1268 return true;
1269 }
1270
1271 bool is_in_young(const oop obj) {
1272 HeapRegion* hr = heap_region_containing(obj);
1273 return hr != NULL && hr->is_young();
1274 }
1275
1276 #ifdef ASSERT
1277 virtual bool is_in_partial_collection(const void* p);
1278 #endif
1279
1280 virtual bool is_scavengable(const void* addr);
1281
1282 // We don't need barriers for initializing stores to objects
1283 // in the young gen: for the SATB pre-barrier, there is no
1284 // pre-value that needs to be remembered; for the remembered-set
1285 // update logging post-barrier, we don't maintain remembered set
1286 // information for young gen objects. Note that non-generational
1287 // G1 does not have any "young" objects, should not elide
1288 // the rs logging barrier and so should always answer false below.
1289 // However, non-generational G1 (-XX:-G1Gen) appears to have
1290 // bit-rotted so was not tested below.
1291 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1292 // Re 6920090, 6920109 above.
1293 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1294 assert(G1Gen || !is_in_young(new_obj),
1295 "Non-generational G1 should never return true below");
1296 return is_in_young(new_obj);
1297 }
1298
1299 // Can a compiler elide a store barrier when it writes
1300 // a permanent oop into the heap? Applies when the compiler
1301 // is storing x to the heap, where x->is_perm() is true.
1302 virtual bool can_elide_permanent_oop_store_barriers() const {
1303 // At least until perm gen collection is also G1-ified, at
1304 // which point this should return false.
1305 return true;
1306 }
1307
1308 // Returns "true" iff the given word_size is "very large".
1309 static bool isHumongous(size_t word_size) {
1310 // Note this has to be strictly greater-than as the TLABs
1311 // are capped at the humongous thresold and we want to
1312 // ensure that we don't try to allocate a TLAB as
1313 // humongous and that we don't allocate a humongous
1314 // object in a TLAB.
1315 return word_size > _humongous_object_threshold_in_words;
1316 }
1317
1318 // Update mod union table with the set of dirty cards.
1319 void updateModUnion();
1320
1321 // Set the mod union bits corresponding to the given memRegion. Note
1322 // that this is always a safe operation, since it doesn't clear any
1323 // bits.
1324 void markModUnionRange(MemRegion mr);
1325
1326 // Records the fact that a marking phase is no longer in progress.
1327 void set_marking_complete() {
1328 _mark_in_progress = false;
1329 }
1330 void set_marking_started() {
1331 _mark_in_progress = true;
1332 }
1333 bool mark_in_progress() {
1334 return _mark_in_progress;
1335 }
1336
1337 // Print the maximum heap capacity.
1338 virtual size_t max_capacity() const;
1339
1340 virtual jlong millis_since_last_gc();
1341
1342 // Perform any cleanup actions necessary before allowing a verification.
1343 virtual void prepare_for_verify();
1344
1345 // Perform verification.
1346
1347 // vo == UsePrevMarking -> use "prev" marking information,
1348 // vo == UseNextMarking -> use "next" marking information
1349 // vo == UseMarkWord -> use the mark word in the object header
1350 //
1351 // NOTE: Only the "prev" marking information is guaranteed to be
1352 // consistent most of the time, so most calls to this should use
1353 // vo == UsePrevMarking.
1354 // Currently, there is only one case where this is called with
1355 // vo == UseNextMarking, which is to verify the "next" marking
1356 // information at the end of remark.
1357 // Currently there is only one place where this is called with
1358 // vo == UseMarkWord, which is to verify the marking during a
1359 // full GC.
1360 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1361
1362 // Override; it uses the "prev" marking information
1363 virtual void verify(bool allow_dirty, bool silent);
1364 // Default behavior by calling print(tty);
1365 virtual void print() const;
1366 // This calls print_on(st, PrintHeapAtGCExtended).
1367 virtual void print_on(outputStream* st) const;
1368 // If extended is true, it will print out information for all
1369 // regions in the heap by calling print_on_extended(st).
1370 virtual void print_on(outputStream* st, bool extended) const;
1371 virtual void print_on_extended(outputStream* st) const;
1372
1373 virtual void print_gc_threads_on(outputStream* st) const;
1374 virtual void gc_threads_do(ThreadClosure* tc) const;
1375
1376 // Override
1377 void print_tracing_info() const;
1378
1379 // The following two methods are helpful for debugging RSet issues.
1380 void print_cset_rsets() PRODUCT_RETURN;
1381 void print_all_rsets() PRODUCT_RETURN;
1382
1383 // Convenience function to be used in situations where the heap type can be
1384 // asserted to be this type.
1385 static G1CollectedHeap* heap();
1386
1387 void empty_young_list();
1388
1389 void set_region_short_lived_locked(HeapRegion* hr);
1390 // add appropriate methods for any other surv rate groups
1391
1392 YoungList* young_list() { return _young_list; }
1393
1394 // debugging
1395 bool check_young_list_well_formed() {
1396 return _young_list->check_list_well_formed();
1397 }
1398
1399 bool check_young_list_empty(bool check_heap,
1400 bool check_sample = true);
1401
1402 // *** Stuff related to concurrent marking. It's not clear to me that so
1403 // many of these need to be public.
1404
1405 // The functions below are helper functions that a subclass of
1406 // "CollectedHeap" can use in the implementation of its virtual
1407 // functions.
1408 // This performs a concurrent marking of the live objects in a
1409 // bitmap off to the side.
1410 void doConcurrentMark();
1411
1412 // Do a full concurrent marking, synchronously.
1413 void do_sync_mark();
1414
1415 bool isMarkedPrev(oop obj) const;
1416 bool isMarkedNext(oop obj) const;
1417
1418 // vo == UsePrevMarking -> use "prev" marking information,
1419 // vo == UseNextMarking -> use "next" marking information,
1420 // vo == UseMarkWord -> use mark word from object header
1421 bool is_obj_dead_cond(const oop obj,
1422 const HeapRegion* hr,
1423 const VerifyOption vo) const {
1424
1425 switch (vo) {
1426 case VerifyOption_G1UsePrevMarking:
1427 return is_obj_dead(obj, hr);
1428 case VerifyOption_G1UseNextMarking:
1429 return is_obj_ill(obj, hr);
1430 default:
1431 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1432 return !obj->is_gc_marked();
1433 }
1434 }
1435
1436 // Determine if an object is dead, given the object and also
1437 // the region to which the object belongs. An object is dead
1438 // iff a) it was not allocated since the last mark and b) it
1439 // is not marked.
1440
1441 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1442 return
1443 !hr->obj_allocated_since_prev_marking(obj) &&
1444 !isMarkedPrev(obj);
1445 }
1446
1447 // This is used when copying an object to survivor space.
1448 // If the object is marked live, then we mark the copy live.
1449 // If the object is allocated since the start of this mark
1450 // cycle, then we mark the copy live.
1451 // If the object has been around since the previous mark
1452 // phase, and hasn't been marked yet during this phase,
1453 // then we don't mark it, we just wait for the
1454 // current marking cycle to get to it.
1455
1456 // This function returns true when an object has been
1457 // around since the previous marking and hasn't yet
1458 // been marked during this marking.
1459
1460 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1461 return
1462 !hr->obj_allocated_since_next_marking(obj) &&
1463 !isMarkedNext(obj);
1464 }
1465
1466 // Determine if an object is dead, given only the object itself.
1467 // This will find the region to which the object belongs and
1468 // then call the region version of the same function.
1469
1470 // Added if it is in permanent gen it isn't dead.
1471 // Added if it is NULL it isn't dead.
1472
1473 // vo == UsePrevMarking -> use "prev" marking information,
1474 // vo == UseNextMarking -> use "next" marking information,
1475 // vo == UseMarkWord -> use mark word from object header
1476 bool is_obj_dead_cond(const oop obj,
1477 const VerifyOption vo) const {
1478
1479 switch (vo) {
1480 case VerifyOption_G1UsePrevMarking:
1481 return is_obj_dead(obj);
1482 case VerifyOption_G1UseNextMarking:
1483 return is_obj_ill(obj);
1484 default:
1485 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1486 return !obj->is_gc_marked();
1487 }
1488 }
1489
1490 bool is_obj_dead(const oop obj) const {
1491 const HeapRegion* hr = heap_region_containing(obj);
1492 if (hr == NULL) {
1493 if (Universe::heap()->is_in_permanent(obj))
1494 return false;
1495 else if (obj == NULL) return false;
1496 else return true;
1497 }
1498 else return is_obj_dead(obj, hr);
1499 }
1500
1501 bool is_obj_ill(const oop obj) const {
1502 const HeapRegion* hr = heap_region_containing(obj);
1503 if (hr == NULL) {
1504 if (Universe::heap()->is_in_permanent(obj))
1505 return false;
1506 else if (obj == NULL) return false;
1507 else return true;
1508 }
1509 else return is_obj_ill(obj, hr);
1510 }
1511
1512 // The following is just to alert the verification code
1513 // that a full collection has occurred and that the
1514 // remembered sets are no longer up to date.
1515 bool _full_collection;
1516 void set_full_collection() { _full_collection = true;}
1517 void clear_full_collection() {_full_collection = false;}
1518 bool full_collection() {return _full_collection;}
1519
1520 ConcurrentMark* concurrent_mark() const { return _cm; }
1521 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1522
1523 // The dirty cards region list is used to record a subset of regions
1524 // whose cards need clearing. The list if populated during the
1525 // remembered set scanning and drained during the card table
1526 // cleanup. Although the methods are reentrant, population/draining
1527 // phases must not overlap. For synchronization purposes the last
1528 // element on the list points to itself.
1529 HeapRegion* _dirty_cards_region_list;
1530 void push_dirty_cards_region(HeapRegion* hr);
1531 HeapRegion* pop_dirty_cards_region();
1532
1533 public:
1534 void stop_conc_gc_threads();
1535
1536 // <NEW PREDICTION>
1537
1538 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1539 void check_if_region_is_too_expensive(double predicted_time_ms);
1540 size_t pending_card_num();
1541 size_t max_pending_card_num();
1542 size_t cards_scanned();
1543
1544 // </NEW PREDICTION>
1545
1546 protected:
1547 size_t _max_heap_capacity;
1548 };
1549
1550 #define use_local_bitmaps 1
1551 #define verify_local_bitmaps 0
1552 #define oop_buffer_length 256
1553
1554 #ifndef PRODUCT
1555 class GCLabBitMap;
1556 class GCLabBitMapClosure: public BitMapClosure {
1557 private:
1558 ConcurrentMark* _cm;
1559 GCLabBitMap* _bitmap;
1560
1561 public:
1562 GCLabBitMapClosure(ConcurrentMark* cm,
1563 GCLabBitMap* bitmap) {
1564 _cm = cm;
1565 _bitmap = bitmap;
1566 }
1567
1568 virtual bool do_bit(size_t offset);
1569 };
1570 #endif // !PRODUCT
1571
1572 class GCLabBitMap: public BitMap {
1573 private:
1574 ConcurrentMark* _cm;
1575
1576 int _shifter;
1577 size_t _bitmap_word_covers_words;
1578
1579 // beginning of the heap
1580 HeapWord* _heap_start;
1581
1582 // this is the actual start of the GCLab
1583 HeapWord* _real_start_word;
1584
1585 // this is the actual end of the GCLab
1586 HeapWord* _real_end_word;
1587
1588 // this is the first word, possibly located before the actual start
1589 // of the GCLab, that corresponds to the first bit of the bitmap
1590 HeapWord* _start_word;
1591
1592 // size of a GCLab in words
1593 size_t _gclab_word_size;
1594
1595 static int shifter() {
1596 return MinObjAlignment - 1;
1597 }
1598
1599 // how many heap words does a single bitmap word corresponds to?
1600 static size_t bitmap_word_covers_words() {
1601 return BitsPerWord << shifter();
1602 }
1603
1604 size_t gclab_word_size() const {
1605 return _gclab_word_size;
1606 }
1607
1608 // Calculates actual GCLab size in words
1609 size_t gclab_real_word_size() const {
1610 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1611 / BitsPerWord;
1612 }
1613
1614 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1615 size_t bits_in_bitmap = gclab_word_size >> shifter();
1616 // We are going to ensure that the beginning of a word in this
1617 // bitmap also corresponds to the beginning of a word in the
1618 // global marking bitmap. To handle the case where a GCLab
1619 // starts from the middle of the bitmap, we need to add enough
1620 // space (i.e. up to a bitmap word) to ensure that we have
1621 // enough bits in the bitmap.
1622 return bits_in_bitmap + BitsPerWord - 1;
1623 }
1624 public:
1625 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1626 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1627 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1628 _shifter(shifter()),
1629 _bitmap_word_covers_words(bitmap_word_covers_words()),
1630 _heap_start(heap_start),
1631 _gclab_word_size(gclab_word_size),
1632 _real_start_word(NULL),
1633 _real_end_word(NULL),
1634 _start_word(NULL)
1635 {
1636 guarantee( size_in_words() >= bitmap_size_in_words(),
1637 "just making sure");
1638 }
1639
1640 inline unsigned heapWordToOffset(HeapWord* addr) {
1641 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1642 assert(offset < size(), "offset should be within bounds");
1643 return offset;
1644 }
1645
1646 inline HeapWord* offsetToHeapWord(size_t offset) {
1647 HeapWord* addr = _start_word + (offset << _shifter);
1648 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1649 return addr;
1650 }
1651
1652 bool fields_well_formed() {
1653 bool ret1 = (_real_start_word == NULL) &&
1654 (_real_end_word == NULL) &&
1655 (_start_word == NULL);
1656 if (ret1)
1657 return true;
1658
1659 bool ret2 = _real_start_word >= _start_word &&
1660 _start_word < _real_end_word &&
1661 (_real_start_word + _gclab_word_size) == _real_end_word &&
1662 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1663 > _real_end_word;
1664 return ret2;
1665 }
1666
1667 inline bool mark(HeapWord* addr) {
1668 guarantee(use_local_bitmaps, "invariant");
1669 assert(fields_well_formed(), "invariant");
1670
1671 if (addr >= _real_start_word && addr < _real_end_word) {
1672 assert(!isMarked(addr), "should not have already been marked");
1673
1674 // first mark it on the bitmap
1675 at_put(heapWordToOffset(addr), true);
1676
1677 return true;
1678 } else {
1679 return false;
1680 }
1681 }
1682
1683 inline bool isMarked(HeapWord* addr) {
1684 guarantee(use_local_bitmaps, "invariant");
1685 assert(fields_well_formed(), "invariant");
1686
1687 return at(heapWordToOffset(addr));
1688 }
1689
1690 void set_buffer(HeapWord* start) {
1691 guarantee(use_local_bitmaps, "invariant");
1692 clear();
1693
1694 assert(start != NULL, "invariant");
1695 _real_start_word = start;
1696 _real_end_word = start + _gclab_word_size;
1697
1698 size_t diff =
1699 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1700 _start_word = start - diff;
1701
1702 assert(fields_well_formed(), "invariant");
1703 }
1704
1705 #ifndef PRODUCT
1706 void verify() {
1707 // verify that the marks have been propagated
1708 GCLabBitMapClosure cl(_cm, this);
1709 iterate(&cl);
1710 }
1711 #endif // PRODUCT
1712
1713 void retire() {
1714 guarantee(use_local_bitmaps, "invariant");
1715 assert(fields_well_formed(), "invariant");
1716
1717 if (_start_word != NULL) {
1718 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1719
1720 // this means that the bitmap was set up for the GCLab
1721 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1722
1723 mark_bitmap->mostly_disjoint_range_union(this,
1724 0, // always start from the start of the bitmap
1725 _start_word,
1726 gclab_real_word_size());
1727 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1728
1729 #ifndef PRODUCT
1730 if (use_local_bitmaps && verify_local_bitmaps)
1731 verify();
1732 #endif // PRODUCT
1733 } else {
1734 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1735 }
1736 }
1737
1738 size_t bitmap_size_in_words() const {
1739 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1740 }
1741
1742 };
1743
1744 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1745 private:
1746 bool _retired;
1747 bool _during_marking;
1748 GCLabBitMap _bitmap;
1749
1750 public:
1751 G1ParGCAllocBuffer(size_t gclab_word_size) :
1752 ParGCAllocBuffer(gclab_word_size),
1753 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1754 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1755 _retired(false)
1756 { }
1757
1758 inline bool mark(HeapWord* addr) {
1759 guarantee(use_local_bitmaps, "invariant");
1760 assert(_during_marking, "invariant");
1761 return _bitmap.mark(addr);
1762 }
1763
1764 inline void set_buf(HeapWord* buf) {
1765 if (use_local_bitmaps && _during_marking)
1766 _bitmap.set_buffer(buf);
1767 ParGCAllocBuffer::set_buf(buf);
1768 _retired = false;
1769 }
1770
1771 inline void retire(bool end_of_gc, bool retain) {
1772 if (_retired)
1773 return;
1774 if (use_local_bitmaps && _during_marking) {
1775 _bitmap.retire();
1776 }
1777 ParGCAllocBuffer::retire(end_of_gc, retain);
1778 _retired = true;
1779 }
1780 };
1781
1782 class G1ParScanThreadState : public StackObj {
1783 protected:
1784 G1CollectedHeap* _g1h;
1785 RefToScanQueue* _refs;
1786 DirtyCardQueue _dcq;
1787 CardTableModRefBS* _ct_bs;
1788 G1RemSet* _g1_rem;
1789
1790 G1ParGCAllocBuffer _surviving_alloc_buffer;
1791 G1ParGCAllocBuffer _tenured_alloc_buffer;
1792 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1793 ageTable _age_table;
1794
1795 size_t _alloc_buffer_waste;
1796 size_t _undo_waste;
1797
1798 OopsInHeapRegionClosure* _evac_failure_cl;
1799 G1ParScanHeapEvacClosure* _evac_cl;
1800 G1ParScanPartialArrayClosure* _partial_scan_cl;
1801
1802 int _hash_seed;
1803 int _queue_num;
1804
1805 size_t _term_attempts;
1806
1807 double _start;
1808 double _start_strong_roots;
1809 double _strong_roots_time;
1810 double _start_term;
1811 double _term_time;
1812
1813 // Map from young-age-index (0 == not young, 1 is youngest) to
1814 // surviving words. base is what we get back from the malloc call
1815 size_t* _surviving_young_words_base;
1816 // this points into the array, as we use the first few entries for padding
1817 size_t* _surviving_young_words;
1818
1819 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1820
1821 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1822
1823 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1824
1825 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1826 CardTableModRefBS* ctbs() { return _ct_bs; }
1827
1828 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1829 if (!from->is_survivor()) {
1830 _g1_rem->par_write_ref(from, p, tid);
1831 }
1832 }
1833
1834 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1835 // If the new value of the field points to the same region or
1836 // is the to-space, we don't need to include it in the Rset updates.
1837 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1838 size_t card_index = ctbs()->index_for(p);
1839 // If the card hasn't been added to the buffer, do it.
1840 if (ctbs()->mark_card_deferred(card_index)) {
1841 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1842 }
1843 }
1844 }
1845
1846 public:
1847 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1848
1849 ~G1ParScanThreadState() {
1850 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1851 }
1852
1853 RefToScanQueue* refs() { return _refs; }
1854 ageTable* age_table() { return &_age_table; }
1855
1856 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1857 return _alloc_buffers[purpose];
1858 }
1859
1860 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1861 size_t undo_waste() const { return _undo_waste; }
1862
1863 #ifdef ASSERT
1864 bool verify_ref(narrowOop* ref) const;
1865 bool verify_ref(oop* ref) const;
1866 bool verify_task(StarTask ref) const;
1867 #endif // ASSERT
1868
1869 template <class T> void push_on_queue(T* ref) {
1870 assert(verify_ref(ref), "sanity");
1871 refs()->push(ref);
1872 }
1873
1874 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1875 if (G1DeferredRSUpdate) {
1876 deferred_rs_update(from, p, tid);
1877 } else {
1878 immediate_rs_update(from, p, tid);
1879 }
1880 }
1881
1882 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1883
1884 HeapWord* obj = NULL;
1885 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1886 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1887 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1888 assert(gclab_word_size == alloc_buf->word_sz(),
1889 "dynamic resizing is not supported");
1890 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1891 alloc_buf->retire(false, false);
1892
1893 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1894 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1895 // Otherwise.
1896 alloc_buf->set_buf(buf);
1897
1898 obj = alloc_buf->allocate(word_sz);
1899 assert(obj != NULL, "buffer was definitely big enough...");
1900 } else {
1901 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1902 }
1903 return obj;
1904 }
1905
1906 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1907 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1908 if (obj != NULL) return obj;
1909 return allocate_slow(purpose, word_sz);
1910 }
1911
1912 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1913 if (alloc_buffer(purpose)->contains(obj)) {
1914 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1915 "should contain whole object");
1916 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1917 } else {
1918 CollectedHeap::fill_with_object(obj, word_sz);
1919 add_to_undo_waste(word_sz);
1920 }
1921 }
1922
1923 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1924 _evac_failure_cl = evac_failure_cl;
1925 }
1926 OopsInHeapRegionClosure* evac_failure_closure() {
1927 return _evac_failure_cl;
1928 }
1929
1930 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1931 _evac_cl = evac_cl;
1932 }
1933
1934 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1935 _partial_scan_cl = partial_scan_cl;
1936 }
1937
1938 int* hash_seed() { return &_hash_seed; }
1939 int queue_num() { return _queue_num; }
1940
1941 size_t term_attempts() const { return _term_attempts; }
1942 void note_term_attempt() { _term_attempts++; }
1943
1944 void start_strong_roots() {
1945 _start_strong_roots = os::elapsedTime();
1946 }
1947 void end_strong_roots() {
1948 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1949 }
1950 double strong_roots_time() const { return _strong_roots_time; }
1951
1952 void start_term_time() {
1953 note_term_attempt();
1954 _start_term = os::elapsedTime();
1955 }
1956 void end_term_time() {
1957 _term_time += (os::elapsedTime() - _start_term);
1958 }
1959 double term_time() const { return _term_time; }
1960
1961 double elapsed_time() const {
1962 return os::elapsedTime() - _start;
1963 }
1964
1965 static void
1966 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1967 void
1968 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1969
1970 size_t* surviving_young_words() {
1971 // We add on to hide entry 0 which accumulates surviving words for
1972 // age -1 regions (i.e. non-young ones)
1973 return _surviving_young_words;
1974 }
1975
1976 void retire_alloc_buffers() {
1977 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1978 size_t waste = _alloc_buffers[ap]->words_remaining();
1979 add_to_alloc_buffer_waste(waste);
1980 _alloc_buffers[ap]->retire(true, false);
1981 }
1982 }
1983
1984 template <class T> void deal_with_reference(T* ref_to_scan) {
1985 if (has_partial_array_mask(ref_to_scan)) {
1986 _partial_scan_cl->do_oop_nv(ref_to_scan);
1987 } else {
1988 // Note: we can use "raw" versions of "region_containing" because
1989 // "obj_to_scan" is definitely in the heap, and is not in a
1990 // humongous region.
1991 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1992 _evac_cl->set_region(r);
1993 _evac_cl->do_oop_nv(ref_to_scan);
1994 }
1995 }
1996
1997 void deal_with_reference(StarTask ref) {
1998 assert(verify_task(ref), "sanity");
1999 if (ref.is_narrow()) {
2000 deal_with_reference((narrowOop*)ref);
2001 } else {
2002 deal_with_reference((oop*)ref);
2003 }
2004 }
2005
2006 public:
2007 void trim_queue();
2008 };
2009
2010 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP