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 *
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/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 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // refence processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 void do_object(oop p) { assert(false, "Do not call."); }
168 bool do_object_b(oop p);
169 };
170
171 class SurvivorGCAllocRegion : public G1AllocRegion {
172 protected:
173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
175 public:
176 SurvivorGCAllocRegion()
177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
178 };
179
180 class OldGCAllocRegion : public G1AllocRegion {
181 protected:
182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
184 public:
185 OldGCAllocRegion()
186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
187 };
188
189 class RefineCardTableEntryClosure;
190
191 class G1CollectedHeap : public SharedHeap {
192 friend class VM_G1CollectForAllocation;
193 friend class VM_GenCollectForPermanentAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
200
201 // Closures used in implementation.
202 friend class G1ParCopyHelper;
203 friend class G1IsAliveClosure;
204 friend class G1EvacuateFollowersClosure;
205 friend class G1ParScanThreadState;
206 friend class G1ParScanClosureSuper;
207 friend class G1ParEvacuateFollowersClosure;
208 friend class G1ParTask;
209 friend class G1FreeGarbageRegionClosure;
210 friend class RefineCardTableEntryClosure;
211 friend class G1PrepareCompactClosure;
212 friend class RegionSorter;
213 friend class RegionResetter;
214 friend class CountRCClosure;
215 friend class EvacPopObjClosure;
216 friend class G1ParCleanupCTTask;
217
218 // Other related classes.
219 friend class G1MarkSweep;
220
221 private:
222 // The one and only G1CollectedHeap, so static functions can find it.
223 static G1CollectedHeap* _g1h;
224
225 static size_t _humongous_object_threshold_in_words;
226
227 // Storage for the G1 heap (excludes the permanent generation).
228 VirtualSpace _g1_storage;
229 MemRegion _g1_reserved;
230
231 // The part of _g1_storage that is currently committed.
232 MemRegion _g1_committed;
233
234 // The master free list. It will satisfy all new region allocations.
235 MasterFreeRegionList _free_list;
236
237 // The secondary free list which contains regions that have been
238 // freed up during the cleanup process. This will be appended to the
239 // master free list when appropriate.
240 SecondaryFreeRegionList _secondary_free_list;
241
242 // It keeps track of the humongous regions.
243 MasterHumongousRegionSet _humongous_set;
244
245 // The number of regions we could create by expansion.
246 size_t _expansion_regions;
247
248 // The block offset table for the G1 heap.
249 G1BlockOffsetSharedArray* _bot_shared;
250
251 // Move all of the regions off the free lists, then rebuild those free
252 // lists, before and after full GC.
253 void tear_down_region_lists();
254 void rebuild_region_lists();
255
256 // The sequence of all heap regions in the heap.
257 HeapRegionSeq _hrs;
258
259 // Alloc region used to satisfy mutator allocation requests.
260 MutatorAllocRegion _mutator_alloc_region;
261
262 // Alloc region used to satisfy allocation requests by the GC for
263 // survivor objects.
264 SurvivorGCAllocRegion _survivor_gc_alloc_region;
265
266 // Alloc region used to satisfy allocation requests by the GC for
267 // old objects.
268 OldGCAllocRegion _old_gc_alloc_region;
269
270 // The last old region we allocated to during the last GC.
271 // Typically, it is not full so we should re-use it during the next GC.
272 HeapRegion* _retained_old_gc_alloc_region;
273
274 // It resets the mutator alloc region before new allocations can take place.
275 void init_mutator_alloc_region();
276
277 // It releases the mutator alloc region.
278 void release_mutator_alloc_region();
279
280 // It initializes the GC alloc regions at the start of a GC.
281 void init_gc_alloc_regions();
282
283 // It releases the GC alloc regions at the end of a GC.
284 void release_gc_alloc_regions();
285
286 // It does any cleanup that needs to be done on the GC alloc regions
287 // before a Full GC.
288 void abandon_gc_alloc_regions();
289
290 // Helper for monitoring and management support.
291 G1MonitoringSupport* _g1mm;
292
293 // Determines PLAB size for a particular allocation purpose.
294 static size_t desired_plab_sz(GCAllocPurpose purpose);
295
296 // Outside of GC pauses, the number of bytes used in all regions other
297 // than the current allocation region.
298 size_t _summary_bytes_used;
299
300 // This is used for a quick test on whether a reference points into
301 // the collection set or not. Basically, we have an array, with one
302 // byte per region, and that byte denotes whether the corresponding
303 // region is in the collection set or not. The entry corresponding
304 // the bottom of the heap, i.e., region 0, is pointed to by
305 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
306 // biased so that it actually points to address 0 of the address
307 // space, to make the test as fast as possible (we can simply shift
308 // the address to address into it, instead of having to subtract the
309 // bottom of the heap from the address before shifting it; basically
310 // it works in the same way the card table works).
311 bool* _in_cset_fast_test;
312
313 // The allocated array used for the fast test on whether a reference
314 // points into the collection set or not. This field is also used to
315 // free the array.
316 bool* _in_cset_fast_test_base;
317
318 // The length of the _in_cset_fast_test_base array.
319 size_t _in_cset_fast_test_length;
320
321 volatile unsigned _gc_time_stamp;
322
323 size_t* _surviving_young_words;
324
325 G1HRPrinter _hr_printer;
326
327 void setup_surviving_young_words();
328 void update_surviving_young_words(size_t* surv_young_words);
329 void cleanup_surviving_young_words();
330
331 // It decides whether an explicit GC should start a concurrent cycle
332 // instead of doing a STW GC. Currently, a concurrent cycle is
333 // explicitly started if:
334 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
335 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
336 bool should_do_concurrent_full_gc(GCCause::Cause cause);
337
338 // Keeps track of how many "full collections" (i.e., Full GCs or
339 // concurrent cycles) we have completed. The number of them we have
340 // started is maintained in _total_full_collections in CollectedHeap.
341 volatile unsigned int _full_collections_completed;
342
343 // This is a non-product method that is helpful for testing. It is
344 // called at the end of a GC and artificially expands the heap by
345 // allocating a number of dead regions. This way we can induce very
346 // frequent marking cycles and stress the cleanup / concurrent
347 // cleanup code more (as all the regions that will be allocated by
348 // this method will be found dead by the marking cycle).
349 void allocate_dummy_regions() PRODUCT_RETURN;
350
351 // These are macros so that, if the assert fires, we get the correct
352 // line number, file, etc.
353
354 #define heap_locking_asserts_err_msg(_extra_message_) \
355 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
356 (_extra_message_), \
357 BOOL_TO_STR(Heap_lock->owned_by_self()), \
358 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
359 BOOL_TO_STR(Thread::current()->is_VM_thread()))
360
361 #define assert_heap_locked() \
362 do { \
363 assert(Heap_lock->owned_by_self(), \
364 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
365 } while (0)
366
367 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
368 do { \
369 assert(Heap_lock->owned_by_self() || \
370 (SafepointSynchronize::is_at_safepoint() && \
371 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
372 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
373 "should be at a safepoint")); \
374 } while (0)
375
376 #define assert_heap_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 be holding the Heap_lock and " \
381 "should not be at a safepoint")); \
382 } while (0)
383
384 #define assert_heap_not_locked() \
385 do { \
386 assert(!Heap_lock->owned_by_self(), \
387 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
388 } while (0)
389
390 #define assert_heap_not_locked_and_not_at_safepoint() \
391 do { \
392 assert(!Heap_lock->owned_by_self() && \
393 !SafepointSynchronize::is_at_safepoint(), \
394 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
395 "should not be at a safepoint")); \
396 } while (0)
397
398 #define assert_at_safepoint(_should_be_vm_thread_) \
399 do { \
400 assert(SafepointSynchronize::is_at_safepoint() && \
401 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
402 heap_locking_asserts_err_msg("should be at a safepoint")); \
403 } while (0)
404
405 #define assert_not_at_safepoint() \
406 do { \
407 assert(!SafepointSynchronize::is_at_safepoint(), \
408 heap_locking_asserts_err_msg("should not be at a safepoint")); \
409 } while (0)
410
411 protected:
412
413 // The young region list.
414 YoungList* _young_list;
415
416 // The current policy object for the collector.
417 G1CollectorPolicy* _g1_policy;
418
419 // This is the second level of trying to allocate a new region. If
420 // new_region() didn't find a region on the free_list, this call will
421 // check whether there's anything available on the
422 // secondary_free_list and/or wait for more regions to appear on
423 // that list, if _free_regions_coming is set.
424 HeapRegion* new_region_try_secondary_free_list();
425
426 // Try to allocate a single non-humongous HeapRegion sufficient for
427 // an allocation of the given word_size. If do_expand is true,
428 // attempt to expand the heap if necessary to satisfy the allocation
429 // request.
430 HeapRegion* new_region(size_t word_size, bool do_expand);
431
432 // Attempt to satisfy a humongous allocation request of the given
433 // size by finding a contiguous set of free regions of num_regions
434 // length and remove them from the master free list. Return the
435 // index of the first region or G1_NULL_HRS_INDEX if the search
436 // was unsuccessful.
437 size_t humongous_obj_allocate_find_first(size_t num_regions,
438 size_t word_size);
439
440 // Initialize a contiguous set of free regions of length num_regions
441 // and starting at index first so that they appear as a single
442 // humongous region.
443 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
444 size_t num_regions,
445 size_t word_size);
446
447 // Attempt to allocate a humongous object of the given size. Return
448 // NULL if unsuccessful.
449 HeapWord* humongous_obj_allocate(size_t word_size);
450
451 // The following two methods, allocate_new_tlab() and
452 // mem_allocate(), are the two main entry points from the runtime
453 // into the G1's allocation routines. They have the following
454 // assumptions:
455 //
456 // * They should both be called outside safepoints.
457 //
458 // * They should both be called without holding the Heap_lock.
459 //
460 // * All allocation requests for new TLABs should go to
461 // allocate_new_tlab().
462 //
463 // * All non-TLAB allocation requests should go to mem_allocate().
464 //
465 // * If either call cannot satisfy the allocation request using the
466 // current allocating region, they will try to get a new one. If
467 // this fails, they will attempt to do an evacuation pause and
468 // retry the allocation.
469 //
470 // * If all allocation attempts fail, even after trying to schedule
471 // an evacuation pause, allocate_new_tlab() will return NULL,
472 // whereas mem_allocate() will attempt a heap expansion and/or
473 // schedule a Full GC.
474 //
475 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
476 // should never be called with word_size being humongous. All
477 // humongous allocation requests should go to mem_allocate() which
478 // will satisfy them with a special path.
479
480 virtual HeapWord* allocate_new_tlab(size_t word_size);
481
482 virtual HeapWord* mem_allocate(size_t word_size,
483 bool* gc_overhead_limit_was_exceeded);
484
485 // The following three methods take a gc_count_before_ret
486 // parameter which is used to return the GC count if the method
487 // returns NULL. Given that we are required to read the GC count
488 // while holding the Heap_lock, and these paths will take the
489 // Heap_lock at some point, it's easier to get them to read the GC
490 // count while holding the Heap_lock before they return NULL instead
491 // of the caller (namely: mem_allocate()) having to also take the
492 // Heap_lock just to read the GC count.
493
494 // First-level mutator allocation attempt: try to allocate out of
495 // the mutator alloc region without taking the Heap_lock. This
496 // should only be used for non-humongous allocations.
497 inline HeapWord* attempt_allocation(size_t word_size,
498 unsigned int* gc_count_before_ret);
499
500 // Second-level mutator allocation attempt: take the Heap_lock and
501 // retry the allocation attempt, potentially scheduling a GC
502 // pause. This should only be used for non-humongous allocations.
503 HeapWord* attempt_allocation_slow(size_t word_size,
504 unsigned int* gc_count_before_ret);
505
506 // Takes the Heap_lock and attempts a humongous allocation. It can
507 // potentially schedule a GC pause.
508 HeapWord* attempt_allocation_humongous(size_t word_size,
509 unsigned int* gc_count_before_ret);
510
511 // Allocation attempt that should be called during safepoints (e.g.,
512 // at the end of a successful GC). expect_null_mutator_alloc_region
513 // specifies whether the mutator alloc region is expected to be NULL
514 // or not.
515 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
516 bool expect_null_mutator_alloc_region);
517
518 // It dirties the cards that cover the block so that so that the post
519 // write barrier never queues anything when updating objects on this
520 // block. It is assumed (and in fact we assert) that the block
521 // belongs to a young region.
522 inline void dirty_young_block(HeapWord* start, size_t word_size);
523
524 // Allocate blocks during garbage collection. Will ensure an
525 // allocation region, either by picking one or expanding the
526 // heap, and then allocate a block of the given size. The block
527 // may not be a humongous - it must fit into a single heap region.
528 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
529
530 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
531 HeapRegion* alloc_region,
532 bool par,
533 size_t word_size);
534
535 // Ensure that no further allocations can happen in "r", bearing in mind
536 // that parallel threads might be attempting allocations.
537 void par_allocate_remaining_space(HeapRegion* r);
538
539 // Allocation attempt during GC for a survivor object / PLAB.
540 inline HeapWord* survivor_attempt_allocation(size_t word_size);
541
542 // Allocation attempt during GC for an old object / PLAB.
543 inline HeapWord* old_attempt_allocation(size_t word_size);
544
545 // These methods are the "callbacks" from the G1AllocRegion class.
546
547 // For mutator alloc regions.
548 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
549 void retire_mutator_alloc_region(HeapRegion* alloc_region,
550 size_t allocated_bytes);
551
552 // For GC alloc regions.
553 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
554 GCAllocPurpose ap);
555 void retire_gc_alloc_region(HeapRegion* alloc_region,
556 size_t allocated_bytes, GCAllocPurpose ap);
557
558 // - if explicit_gc is true, the GC is for a System.gc() or a heap
559 // inspection request and should collect the entire heap
560 // - if clear_all_soft_refs is true, all soft references should be
561 // cleared during the GC
562 // - if explicit_gc is false, word_size describes the allocation that
563 // the GC should attempt (at least) to satisfy
564 // - it returns false if it is unable to do the collection due to the
565 // GC locker being active, true otherwise
566 bool do_collection(bool explicit_gc,
567 bool clear_all_soft_refs,
568 size_t word_size);
569
570 // Callback from VM_G1CollectFull operation.
571 // Perform a full collection.
572 void do_full_collection(bool clear_all_soft_refs);
573
574 // Resize the heap if necessary after a full collection. If this is
575 // after a collect-for allocation, "word_size" is the allocation size,
576 // and will be considered part of the used portion of the heap.
577 void resize_if_necessary_after_full_collection(size_t word_size);
578
579 // Callback from VM_G1CollectForAllocation operation.
580 // This function does everything necessary/possible to satisfy a
581 // failed allocation request (including collection, expansion, etc.)
582 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
583
584 // Attempting to expand the heap sufficiently
585 // to support an allocation of the given "word_size". If
586 // successful, perform the allocation and return the address of the
587 // allocated block, or else "NULL".
588 HeapWord* expand_and_allocate(size_t word_size);
589
590 // Process any reference objects discovered during
591 // an incremental evacuation pause.
592 void process_discovered_references();
593
594 // Enqueue any remaining discovered references
595 // after processing.
596 void enqueue_discovered_references();
597
598 public:
599
600 G1MonitoringSupport* g1mm() {
601 assert(_g1mm != NULL, "should have been initialized");
602 return _g1mm;
603 }
604
605 // Expand the garbage-first heap by at least the given size (in bytes!).
606 // Returns true if the heap was expanded by the requested amount;
607 // false otherwise.
608 // (Rounds up to a HeapRegion boundary.)
609 bool expand(size_t expand_bytes);
610
611 // Do anything common to GC's.
612 virtual void gc_prologue(bool full);
613 virtual void gc_epilogue(bool full);
614
615 // We register a region with the fast "in collection set" test. We
616 // simply set to true the array slot corresponding to this region.
617 void register_region_with_in_cset_fast_test(HeapRegion* r) {
618 assert(_in_cset_fast_test_base != NULL, "sanity");
619 assert(r->in_collection_set(), "invariant");
620 size_t index = r->hrs_index();
621 assert(index < _in_cset_fast_test_length, "invariant");
622 assert(!_in_cset_fast_test_base[index], "invariant");
623 _in_cset_fast_test_base[index] = true;
624 }
625
626 // This is a fast test on whether a reference points into the
627 // collection set or not. It does not assume that the reference
628 // points into the heap; if it doesn't, it will return false.
629 bool in_cset_fast_test(oop obj) {
630 assert(_in_cset_fast_test != NULL, "sanity");
631 if (_g1_committed.contains((HeapWord*) obj)) {
632 // no need to subtract the bottom of the heap from obj,
633 // _in_cset_fast_test is biased
634 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
635 bool ret = _in_cset_fast_test[index];
636 // let's make sure the result is consistent with what the slower
637 // test returns
638 assert( ret || !obj_in_cs(obj), "sanity");
639 assert(!ret || obj_in_cs(obj), "sanity");
640 return ret;
641 } else {
642 return false;
643 }
644 }
645
646 void clear_cset_fast_test() {
647 assert(_in_cset_fast_test_base != NULL, "sanity");
648 memset(_in_cset_fast_test_base, false,
649 _in_cset_fast_test_length * sizeof(bool));
650 }
651
652 // This is called at the end of either a concurrent cycle or a Full
653 // GC to update the number of full collections completed. Those two
654 // can happen in a nested fashion, i.e., we start a concurrent
655 // cycle, a Full GC happens half-way through it which ends first,
656 // and then the cycle notices that a Full GC happened and ends
657 // too. The concurrent parameter is a boolean to help us do a bit
658 // tighter consistency checking in the method. If concurrent is
659 // false, the caller is the inner caller in the nesting (i.e., the
660 // Full GC). If concurrent is true, the caller is the outer caller
661 // in this nesting (i.e., the concurrent cycle). Further nesting is
662 // not currently supported. The end of the this call also notifies
663 // the FullGCCount_lock in case a Java thread is waiting for a full
664 // GC to happen (e.g., it called System.gc() with
665 // +ExplicitGCInvokesConcurrent).
666 void increment_full_collections_completed(bool concurrent);
667
668 unsigned int full_collections_completed() {
669 return _full_collections_completed;
670 }
671
672 G1HRPrinter* hr_printer() { return &_hr_printer; }
673
674 protected:
675
676 // Shrink the garbage-first heap by at most the given size (in bytes!).
677 // (Rounds down to a HeapRegion boundary.)
678 virtual void shrink(size_t expand_bytes);
679 void shrink_helper(size_t expand_bytes);
680
681 #if TASKQUEUE_STATS
682 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
683 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
684 void reset_taskqueue_stats();
685 #endif // TASKQUEUE_STATS
686
687 // Schedule the VM operation that will do an evacuation pause to
688 // satisfy an allocation request of word_size. *succeeded will
689 // return whether the VM operation was successful (it did do an
690 // evacuation pause) or not (another thread beat us to it or the GC
691 // locker was active). Given that we should not be holding the
692 // Heap_lock when we enter this method, we will pass the
693 // gc_count_before (i.e., total_collections()) as a parameter since
694 // it has to be read while holding the Heap_lock. Currently, both
695 // methods that call do_collection_pause() release the Heap_lock
696 // before the call, so it's easy to read gc_count_before just before.
697 HeapWord* do_collection_pause(size_t word_size,
698 unsigned int gc_count_before,
699 bool* succeeded);
700
701 // The guts of the incremental collection pause, executed by the vm
702 // thread. It returns false if it is unable to do the collection due
703 // to the GC locker being active, true otherwise
704 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
705
706 // Actually do the work of evacuating the collection set.
707 void evacuate_collection_set();
708
709 // The g1 remembered set of the heap.
710 G1RemSet* _g1_rem_set;
711 // And it's mod ref barrier set, used to track updates for the above.
712 ModRefBarrierSet* _mr_bs;
713
714 // A set of cards that cover the objects for which the Rsets should be updated
715 // concurrently after the collection.
716 DirtyCardQueueSet _dirty_card_queue_set;
717
718 // The Heap Region Rem Set Iterator.
719 HeapRegionRemSetIterator** _rem_set_iterator;
720
721 // The closure used to refine a single card.
722 RefineCardTableEntryClosure* _refine_cte_cl;
723
724 // A function to check the consistency of dirty card logs.
725 void check_ct_logs_at_safepoint();
726
727 // A DirtyCardQueueSet that is used to hold cards that contain
728 // references into the current collection set. This is used to
729 // update the remembered sets of the regions in the collection
730 // set in the event of an evacuation failure.
731 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
732
733 // After a collection pause, make the regions in the CS into free
734 // regions.
735 void free_collection_set(HeapRegion* cs_head);
736
737 // Abandon the current collection set without recording policy
738 // statistics or updating free lists.
739 void abandon_collection_set(HeapRegion* cs_head);
740
741 // Applies "scan_non_heap_roots" to roots outside the heap,
742 // "scan_rs" to roots inside the heap (having done "set_region" to
743 // indicate the region in which the root resides), and does "scan_perm"
744 // (setting the generation to the perm generation.) If "scan_rs" is
745 // NULL, then this step is skipped. The "worker_i"
746 // param is for use with parallel roots processing, and should be
747 // the "i" of the calling parallel worker thread's work(i) function.
748 // In the sequential case this param will be ignored.
749 void g1_process_strong_roots(bool collecting_perm_gen,
750 SharedHeap::ScanningOption so,
751 OopClosure* scan_non_heap_roots,
752 OopsInHeapRegionClosure* scan_rs,
753 OopsInGenClosure* scan_perm,
754 int worker_i);
755
756 // Apply "blk" to all the weak roots of the system. These include
757 // JNI weak roots, the code cache, system dictionary, symbol table,
758 // string table, and referents of reachable weak refs.
759 void g1_process_weak_roots(OopClosure* root_closure,
760 OopClosure* non_root_closure);
761
762 // Frees a non-humongous region by initializing its contents and
763 // adding it to the free list that's passed as a parameter (this is
764 // usually a local list which will be appended to the master free
765 // list later). The used bytes of freed regions are accumulated in
766 // pre_used. If par is true, the region's RSet will not be freed
767 // up. The assumption is that this will be done later.
768 void free_region(HeapRegion* hr,
769 size_t* pre_used,
770 FreeRegionList* free_list,
771 bool par);
772
773 // Frees a humongous region by collapsing it into individual regions
774 // and calling free_region() for each of them. The freed regions
775 // will be added to the free list that's passed as a parameter (this
776 // is usually a local list which will be appended to the master free
777 // list later). The used bytes of freed regions are accumulated in
778 // pre_used. If par is true, the region's RSet will not be freed
779 // up. The assumption is that this will be done later.
780 void free_humongous_region(HeapRegion* hr,
781 size_t* pre_used,
782 FreeRegionList* free_list,
783 HumongousRegionSet* humongous_proxy_set,
784 bool par);
785
786 // Notifies all the necessary spaces that the committed space has
787 // been updated (either expanded or shrunk). It should be called
788 // after _g1_storage is updated.
789 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
790
791 // The concurrent marker (and the thread it runs in.)
792 ConcurrentMark* _cm;
793 ConcurrentMarkThread* _cmThread;
794 bool _mark_in_progress;
795
796 // The concurrent refiner.
797 ConcurrentG1Refine* _cg1r;
798
799 // The parallel task queues
800 RefToScanQueueSet *_task_queues;
801
802 // True iff a evacuation has failed in the current collection.
803 bool _evacuation_failed;
804
805 // Set the attribute indicating whether evacuation has failed in the
806 // current collection.
807 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
808
809 // Failed evacuations cause some logical from-space objects to have
810 // forwarding pointers to themselves. Reset them.
811 void remove_self_forwarding_pointers();
812
813 // When one is non-null, so is the other. Together, they each pair is
814 // an object with a preserved mark, and its mark value.
815 GrowableArray<oop>* _objs_with_preserved_marks;
816 GrowableArray<markOop>* _preserved_marks_of_objs;
817
818 // Preserve the mark of "obj", if necessary, in preparation for its mark
819 // word being overwritten with a self-forwarding-pointer.
820 void preserve_mark_if_necessary(oop obj, markOop m);
821
822 // The stack of evac-failure objects left to be scanned.
823 GrowableArray<oop>* _evac_failure_scan_stack;
824 // The closure to apply to evac-failure objects.
825
826 OopsInHeapRegionClosure* _evac_failure_closure;
827 // Set the field above.
828 void
829 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
830 _evac_failure_closure = evac_failure_closure;
831 }
832
833 // Push "obj" on the scan stack.
834 void push_on_evac_failure_scan_stack(oop obj);
835 // Process scan stack entries until the stack is empty.
836 void drain_evac_failure_scan_stack();
837 // True iff an invocation of "drain_scan_stack" is in progress; to
838 // prevent unnecessary recursion.
839 bool _drain_in_progress;
840
841 // Do any necessary initialization for evacuation-failure handling.
842 // "cl" is the closure that will be used to process evac-failure
843 // objects.
844 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
845 // Do any necessary cleanup for evacuation-failure handling data
846 // structures.
847 void finalize_for_evac_failure();
848
849 // An attempt to evacuate "obj" has failed; take necessary steps.
850 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj,
851 bool should_mark_root);
852 void handle_evacuation_failure_common(oop obj, markOop m);
853
854 // ("Weak") Reference processing support.
855 //
856 // G1 has 2 instances of the referece processor class. One
857 // (_ref_processor_cm) handles reference object discovery
858 // and subsequent processing during concurrent marking cycles.
859 //
860 // The other (_ref_processor_stw) handles reference object
861 // discovery and processing during full GCs and incremental
862 // evacuation pauses.
863 //
864 // During an incremental pause, reference discovery will be
865 // temporarily disabled for _ref_processor_cm and will be
866 // enabled for _ref_processor_stw. At the end of the evacuation
867 // pause references discovered by _ref_processor_stw will be
868 // processed and discovery will be disabled. The previous
869 // setting for reference object discovery for _ref_processor_cm
870 // will be re-instated.
871 //
872 // At the start of marking:
873 // * Discovery by the CM ref processor is verified to be inactive
874 // and it's discovered lists are empty.
875 // * Discovery by the CM ref processor is then enabled.
876 //
877 // At the end of marking:
878 // * Any references on the CM ref processor's discovered
879 // lists are processed (possibly MT).
880 //
881 // At the start of full GC we:
882 // * Disable discovery by the CM ref processor and
883 // empty CM ref processor's discovered lists
884 // (without processing any entries).
885 // * Verify that the STW ref processor is inactive and it's
886 // discovered lists are empty.
887 // * Temporarily set STW ref processor discovery as single threaded.
888 // * Temporarily clear the STW ref processor's _is_alive_non_header
889 // field.
890 // * Finally enable discovery by the STW ref processor.
891 //
892 // The STW ref processor is used to record any discovered
893 // references during the full GC.
894 //
895 // At the end of a full GC we:
896 // * Enqueue any reference objects discovered by the STW ref processor
897 // that have non-live referents. This has the side-effect of
898 // making the STW ref processor inactive by disabling discovery.
899 // * Verify that the CM ref processor is still inactive
900 // and no references have been placed on it's discovered
901 // lists (also checked as a precondition during initial marking).
902
903 // The (stw) reference processor...
904 ReferenceProcessor* _ref_processor_stw;
905
906 // During reference object discovery, the _is_alive_non_header
907 // closure (if non-null) is applied to the referent object to
908 // determine whether the referent is live. If so then the
909 // reference object does not need to be 'discovered' and can
910 // be treated as a regular oop. This has the benefit of reducing
911 // the number of 'discovered' reference objects that need to
912 // be processed.
913 //
914 // Instance of the is_alive closure for embedding into the
915 // STW reference processor as the _is_alive_non_header field.
916 // Supplying a value for the _is_alive_non_header field is
917 // optional but doing so prevents unnecessary additions to
918 // the discovered lists during reference discovery.
919 G1STWIsAliveClosure _is_alive_closure_stw;
920
921 // The (concurrent marking) reference processor...
922 ReferenceProcessor* _ref_processor_cm;
923
924 // Instance of the concurrent mark is_alive closure for embedding
925 // into the Concurrent Marking reference processor as the
926 // _is_alive_non_header field. Supplying a value for the
927 // _is_alive_non_header field is optional but doing so prevents
928 // unnecessary additions to the discovered lists during reference
929 // discovery.
930 G1CMIsAliveClosure _is_alive_closure_cm;
931
932 enum G1H_process_strong_roots_tasks {
933 G1H_PS_mark_stack_oops_do,
934 G1H_PS_refProcessor_oops_do,
935 // Leave this one last.
936 G1H_PS_NumElements
937 };
938
939 SubTasksDone* _process_strong_tasks;
940
941 volatile bool _free_regions_coming;
942
943 public:
944
945 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
946
947 void set_refine_cte_cl_concurrency(bool concurrent);
948
949 RefToScanQueue *task_queue(int i) const;
950
951 // A set of cards where updates happened during the GC
952 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
953
954 // A DirtyCardQueueSet that is used to hold cards that contain
955 // references into the current collection set. This is used to
956 // update the remembered sets of the regions in the collection
957 // set in the event of an evacuation failure.
958 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
959 { return _into_cset_dirty_card_queue_set; }
960
961 // Create a G1CollectedHeap with the specified policy.
962 // Must call the initialize method afterwards.
963 // May not return if something goes wrong.
964 G1CollectedHeap(G1CollectorPolicy* policy);
965
966 // Initialize the G1CollectedHeap to have the initial and
967 // maximum sizes, permanent generation, and remembered and barrier sets
968 // specified by the policy object.
969 jint initialize();
970
971 // Initialize weak reference processing.
972 virtual void ref_processing_init();
973
974 void set_par_threads(int t) {
975 SharedHeap::set_par_threads(t);
976 _process_strong_tasks->set_n_threads(t);
977 }
978
979 virtual CollectedHeap::Name kind() const {
980 return CollectedHeap::G1CollectedHeap;
981 }
982
983 // The current policy object for the collector.
984 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
985
986 // Adaptive size policy. No such thing for g1.
987 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
988
989 // The rem set and barrier set.
990 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
991 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
992
993 // The rem set iterator.
994 HeapRegionRemSetIterator* rem_set_iterator(int i) {
995 return _rem_set_iterator[i];
996 }
997
998 HeapRegionRemSetIterator* rem_set_iterator() {
999 return _rem_set_iterator[0];
1000 }
1001
1002 unsigned get_gc_time_stamp() {
1003 return _gc_time_stamp;
1004 }
1005
1006 void reset_gc_time_stamp() {
1007 _gc_time_stamp = 0;
1008 OrderAccess::fence();
1009 }
1010
1011 void increment_gc_time_stamp() {
1012 ++_gc_time_stamp;
1013 OrderAccess::fence();
1014 }
1015
1016 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1017 DirtyCardQueue* into_cset_dcq,
1018 bool concurrent, int worker_i);
1019
1020 // The shared block offset table array.
1021 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1022
1023 // Reference Processing accessors
1024
1025 // The STW reference processor....
1026 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1027
1028 // The Concurent Marking reference processor...
1029 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1030
1031 virtual size_t capacity() const;
1032 virtual size_t used() const;
1033 // This should be called when we're not holding the heap lock. The
1034 // result might be a bit inaccurate.
1035 size_t used_unlocked() const;
1036 size_t recalculate_used() const;
1037
1038 // These virtual functions do the actual allocation.
1039 // Some heaps may offer a contiguous region for shared non-blocking
1040 // allocation, via inlined code (by exporting the address of the top and
1041 // end fields defining the extent of the contiguous allocation region.)
1042 // But G1CollectedHeap doesn't yet support this.
1043
1044 // Return an estimate of the maximum allocation that could be performed
1045 // without triggering any collection or expansion activity. In a
1046 // generational collector, for example, this is probably the largest
1047 // allocation that could be supported (without expansion) in the youngest
1048 // generation. It is "unsafe" because no locks are taken; the result
1049 // should be treated as an approximation, not a guarantee, for use in
1050 // heuristic resizing decisions.
1051 virtual size_t unsafe_max_alloc();
1052
1053 virtual bool is_maximal_no_gc() const {
1054 return _g1_storage.uncommitted_size() == 0;
1055 }
1056
1057 // The total number of regions in the heap.
1058 size_t n_regions() { return _hrs.length(); }
1059
1060 // The max number of regions in the heap.
1061 size_t max_regions() { return _hrs.max_length(); }
1062
1063 // The number of regions that are completely free.
1064 size_t free_regions() { return _free_list.length(); }
1065
1066 // The number of regions that are not completely free.
1067 size_t used_regions() { return n_regions() - free_regions(); }
1068
1069 // The number of regions available for "regular" expansion.
1070 size_t expansion_regions() { return _expansion_regions; }
1071
1072 // Factory method for HeapRegion instances. It will return NULL if
1073 // the allocation fails.
1074 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1075
1076 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1077 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1078 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1079 void verify_dirty_young_regions() PRODUCT_RETURN;
1080
1081 // verify_region_sets() performs verification over the region
1082 // lists. It will be compiled in the product code to be used when
1083 // necessary (i.e., during heap verification).
1084 void verify_region_sets();
1085
1086 // verify_region_sets_optional() is planted in the code for
1087 // list verification in non-product builds (and it can be enabled in
1088 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1089 #if HEAP_REGION_SET_FORCE_VERIFY
1090 void verify_region_sets_optional() {
1091 verify_region_sets();
1092 }
1093 #else // HEAP_REGION_SET_FORCE_VERIFY
1094 void verify_region_sets_optional() { }
1095 #endif // HEAP_REGION_SET_FORCE_VERIFY
1096
1097 #ifdef ASSERT
1098 bool is_on_master_free_list(HeapRegion* hr) {
1099 return hr->containing_set() == &_free_list;
1100 }
1101
1102 bool is_in_humongous_set(HeapRegion* hr) {
1103 return hr->containing_set() == &_humongous_set;
1104 }
1105 #endif // ASSERT
1106
1107 // Wrapper for the region list operations that can be called from
1108 // methods outside this class.
1109
1110 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1111 _secondary_free_list.add_as_tail(list);
1112 }
1113
1114 void append_secondary_free_list() {
1115 _free_list.add_as_head(&_secondary_free_list);
1116 }
1117
1118 void append_secondary_free_list_if_not_empty_with_lock() {
1119 // If the secondary free list looks empty there's no reason to
1120 // take the lock and then try to append it.
1121 if (!_secondary_free_list.is_empty()) {
1122 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1123 append_secondary_free_list();
1124 }
1125 }
1126
1127 void set_free_regions_coming();
1128 void reset_free_regions_coming();
1129 bool free_regions_coming() { return _free_regions_coming; }
1130 void wait_while_free_regions_coming();
1131
1132 // Perform a collection of the heap; intended for use in implementing
1133 // "System.gc". This probably implies as full a collection as the
1134 // "CollectedHeap" supports.
1135 virtual void collect(GCCause::Cause cause);
1136
1137 // The same as above but assume that the caller holds the Heap_lock.
1138 void collect_locked(GCCause::Cause cause);
1139
1140 // This interface assumes that it's being called by the
1141 // vm thread. It collects the heap assuming that the
1142 // heap lock is already held and that we are executing in
1143 // the context of the vm thread.
1144 virtual void collect_as_vm_thread(GCCause::Cause cause);
1145
1146 // True iff a evacuation has failed in the most-recent collection.
1147 bool evacuation_failed() { return _evacuation_failed; }
1148
1149 // It will free a region if it has allocated objects in it that are
1150 // all dead. It calls either free_region() or
1151 // free_humongous_region() depending on the type of the region that
1152 // is passed to it.
1153 void free_region_if_empty(HeapRegion* hr,
1154 size_t* pre_used,
1155 FreeRegionList* free_list,
1156 HumongousRegionSet* humongous_proxy_set,
1157 HRRSCleanupTask* hrrs_cleanup_task,
1158 bool par);
1159
1160 // It appends the free list to the master free list and updates the
1161 // master humongous list according to the contents of the proxy
1162 // list. It also adjusts the total used bytes according to pre_used
1163 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1164 void update_sets_after_freeing_regions(size_t pre_used,
1165 FreeRegionList* free_list,
1166 HumongousRegionSet* humongous_proxy_set,
1167 bool par);
1168
1169 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1170 virtual bool is_in(const void* p) const;
1171
1172 // Return "TRUE" iff the given object address is within the collection
1173 // set.
1174 inline bool obj_in_cs(oop obj);
1175
1176 // Return "TRUE" iff the given object address is in the reserved
1177 // region of g1 (excluding the permanent generation).
1178 bool is_in_g1_reserved(const void* p) const {
1179 return _g1_reserved.contains(p);
1180 }
1181
1182 // Returns a MemRegion that corresponds to the space that has been
1183 // reserved for the heap
1184 MemRegion g1_reserved() {
1185 return _g1_reserved;
1186 }
1187
1188 // Returns a MemRegion that corresponds to the space that has been
1189 // committed in the heap
1190 MemRegion g1_committed() {
1191 return _g1_committed;
1192 }
1193
1194 virtual bool is_in_closed_subset(const void* p) const;
1195
1196 // This resets the card table to all zeros. It is used after
1197 // a collection pause which used the card table to claim cards.
1198 void cleanUpCardTable();
1199
1200 // Iteration functions.
1201
1202 // Iterate over all the ref-containing fields of all objects, calling
1203 // "cl.do_oop" on each.
1204 virtual void oop_iterate(OopClosure* cl) {
1205 oop_iterate(cl, true);
1206 }
1207 void oop_iterate(OopClosure* cl, bool do_perm);
1208
1209 // Same as above, restricted to a memory region.
1210 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1211 oop_iterate(mr, cl, true);
1212 }
1213 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1214
1215 // Iterate over all objects, calling "cl.do_object" on each.
1216 virtual void object_iterate(ObjectClosure* cl) {
1217 object_iterate(cl, true);
1218 }
1219 virtual void safe_object_iterate(ObjectClosure* cl) {
1220 object_iterate(cl, true);
1221 }
1222 void object_iterate(ObjectClosure* cl, bool do_perm);
1223
1224 // Iterate over all objects allocated since the last collection, calling
1225 // "cl.do_object" on each. The heap must have been initialized properly
1226 // to support this function, or else this call will fail.
1227 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1228
1229 // Iterate over all spaces in use in the heap, in ascending address order.
1230 virtual void space_iterate(SpaceClosure* cl);
1231
1232 // Iterate over heap regions, in address order, terminating the
1233 // iteration early if the "doHeapRegion" method returns "true".
1234 void heap_region_iterate(HeapRegionClosure* blk) const;
1235
1236 // Iterate over heap regions starting with r (or the first region if "r"
1237 // is NULL), in address order, terminating early if the "doHeapRegion"
1238 // method returns "true".
1239 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1240
1241 // Return the region with the given index. It assumes the index is valid.
1242 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1243
1244 // Divide the heap region sequence into "chunks" of some size (the number
1245 // of regions divided by the number of parallel threads times some
1246 // overpartition factor, currently 4). Assumes that this will be called
1247 // in parallel by ParallelGCThreads worker threads with discinct worker
1248 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1249 // calls will use the same "claim_value", and that that claim value is
1250 // different from the claim_value of any heap region before the start of
1251 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1252 // attempting to claim the first region in each chunk, and, if
1253 // successful, applying the closure to each region in the chunk (and
1254 // setting the claim value of the second and subsequent regions of the
1255 // chunk.) For now requires that "doHeapRegion" always returns "false",
1256 // i.e., that a closure never attempt to abort a traversal.
1257 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1258 int worker,
1259 jint claim_value);
1260
1261 // It resets all the region claim values to the default.
1262 void reset_heap_region_claim_values();
1263
1264 #ifdef ASSERT
1265 bool check_heap_region_claim_values(jint claim_value);
1266 #endif // ASSERT
1267
1268 // Iterate over the regions (if any) in the current collection set.
1269 void collection_set_iterate(HeapRegionClosure* blk);
1270
1271 // As above but starting from region r
1272 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1273
1274 // Returns the first (lowest address) compactible space in the heap.
1275 virtual CompactibleSpace* first_compactible_space();
1276
1277 // A CollectedHeap will contain some number of spaces. This finds the
1278 // space containing a given address, or else returns NULL.
1279 virtual Space* space_containing(const void* addr) const;
1280
1281 // A G1CollectedHeap will contain some number of heap regions. This
1282 // finds the region containing a given address, or else returns NULL.
1283 template <class T>
1284 inline HeapRegion* heap_region_containing(const T addr) const;
1285
1286 // Like the above, but requires "addr" to be in the heap (to avoid a
1287 // null-check), and unlike the above, may return an continuing humongous
1288 // region.
1289 template <class T>
1290 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1291
1292 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1293 // each address in the (reserved) heap is a member of exactly
1294 // one block. The defining characteristic of a block is that it is
1295 // possible to find its size, and thus to progress forward to the next
1296 // block. (Blocks may be of different sizes.) Thus, blocks may
1297 // represent Java objects, or they might be free blocks in a
1298 // free-list-based heap (or subheap), as long as the two kinds are
1299 // distinguishable and the size of each is determinable.
1300
1301 // Returns the address of the start of the "block" that contains the
1302 // address "addr". We say "blocks" instead of "object" since some heaps
1303 // may not pack objects densely; a chunk may either be an object or a
1304 // non-object.
1305 virtual HeapWord* block_start(const void* addr) const;
1306
1307 // Requires "addr" to be the start of a chunk, and returns its size.
1308 // "addr + size" is required to be the start of a new chunk, or the end
1309 // of the active area of the heap.
1310 virtual size_t block_size(const HeapWord* addr) const;
1311
1312 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1313 // the block is an object.
1314 virtual bool block_is_obj(const HeapWord* addr) const;
1315
1316 // Does this heap support heap inspection? (+PrintClassHistogram)
1317 virtual bool supports_heap_inspection() const { return true; }
1318
1319 // Section on thread-local allocation buffers (TLABs)
1320 // See CollectedHeap for semantics.
1321
1322 virtual bool supports_tlab_allocation() const;
1323 virtual size_t tlab_capacity(Thread* thr) const;
1324 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1325
1326 // Can a compiler initialize a new object without store barriers?
1327 // This permission only extends from the creation of a new object
1328 // via a TLAB up to the first subsequent safepoint. If such permission
1329 // is granted for this heap type, the compiler promises to call
1330 // defer_store_barrier() below on any slow path allocation of
1331 // a new object for which such initializing store barriers will
1332 // have been elided. G1, like CMS, allows this, but should be
1333 // ready to provide a compensating write barrier as necessary
1334 // if that storage came out of a non-young region. The efficiency
1335 // of this implementation depends crucially on being able to
1336 // answer very efficiently in constant time whether a piece of
1337 // storage in the heap comes from a young region or not.
1338 // See ReduceInitialCardMarks.
1339 virtual bool can_elide_tlab_store_barriers() const {
1340 return true;
1341 }
1342
1343 virtual bool card_mark_must_follow_store() const {
1344 return true;
1345 }
1346
1347 bool is_in_young(const oop obj) {
1348 HeapRegion* hr = heap_region_containing(obj);
1349 return hr != NULL && hr->is_young();
1350 }
1351
1352 #ifdef ASSERT
1353 virtual bool is_in_partial_collection(const void* p);
1354 #endif
1355
1356 virtual bool is_scavengable(const void* addr);
1357
1358 // We don't need barriers for initializing stores to objects
1359 // in the young gen: for the SATB pre-barrier, there is no
1360 // pre-value that needs to be remembered; for the remembered-set
1361 // update logging post-barrier, we don't maintain remembered set
1362 // information for young gen objects.
1363 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1364 return is_in_young(new_obj);
1365 }
1366
1367 // Can a compiler elide a store barrier when it writes
1368 // a permanent oop into the heap? Applies when the compiler
1369 // is storing x to the heap, where x->is_perm() is true.
1370 virtual bool can_elide_permanent_oop_store_barriers() const {
1371 // At least until perm gen collection is also G1-ified, at
1372 // which point this should return false.
1373 return true;
1374 }
1375
1376 // Returns "true" iff the given word_size is "very large".
1377 static bool isHumongous(size_t word_size) {
1378 // Note this has to be strictly greater-than as the TLABs
1379 // are capped at the humongous thresold and we want to
1380 // ensure that we don't try to allocate a TLAB as
1381 // humongous and that we don't allocate a humongous
1382 // object in a TLAB.
1383 return word_size > _humongous_object_threshold_in_words;
1384 }
1385
1386 // Update mod union table with the set of dirty cards.
1387 void updateModUnion();
1388
1389 // Set the mod union bits corresponding to the given memRegion. Note
1390 // that this is always a safe operation, since it doesn't clear any
1391 // bits.
1392 void markModUnionRange(MemRegion mr);
1393
1394 // Records the fact that a marking phase is no longer in progress.
1395 void set_marking_complete() {
1396 _mark_in_progress = false;
1397 }
1398 void set_marking_started() {
1399 _mark_in_progress = true;
1400 }
1401 bool mark_in_progress() {
1402 return _mark_in_progress;
1403 }
1404
1405 // Print the maximum heap capacity.
1406 virtual size_t max_capacity() const;
1407
1408 virtual jlong millis_since_last_gc();
1409
1410 // Perform any cleanup actions necessary before allowing a verification.
1411 virtual void prepare_for_verify();
1412
1413 // Perform verification.
1414
1415 // vo == UsePrevMarking -> use "prev" marking information,
1416 // vo == UseNextMarking -> use "next" marking information
1417 // vo == UseMarkWord -> use the mark word in the object header
1418 //
1419 // NOTE: Only the "prev" marking information is guaranteed to be
1420 // consistent most of the time, so most calls to this should use
1421 // vo == UsePrevMarking.
1422 // Currently, there is only one case where this is called with
1423 // vo == UseNextMarking, which is to verify the "next" marking
1424 // information at the end of remark.
1425 // Currently there is only one place where this is called with
1426 // vo == UseMarkWord, which is to verify the marking during a
1427 // full GC.
1428 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1429
1430 // Override; it uses the "prev" marking information
1431 virtual void verify(bool allow_dirty, bool silent);
1432 // Default behavior by calling print(tty);
1433 virtual void print() const;
1434 // This calls print_on(st, PrintHeapAtGCExtended).
1435 virtual void print_on(outputStream* st) const;
1436 // If extended is true, it will print out information for all
1437 // regions in the heap by calling print_on_extended(st).
1438 virtual void print_on(outputStream* st, bool extended) const;
1439 virtual void print_on_extended(outputStream* st) const;
1440
1441 virtual void print_gc_threads_on(outputStream* st) const;
1442 virtual void gc_threads_do(ThreadClosure* tc) const;
1443
1444 // Override
1445 void print_tracing_info() const;
1446
1447 // The following two methods are helpful for debugging RSet issues.
1448 void print_cset_rsets() PRODUCT_RETURN;
1449 void print_all_rsets() PRODUCT_RETURN;
1450
1451 // Convenience function to be used in situations where the heap type can be
1452 // asserted to be this type.
1453 static G1CollectedHeap* heap();
1454
1455 void empty_young_list();
1456
1457 void set_region_short_lived_locked(HeapRegion* hr);
1458 // add appropriate methods for any other surv rate groups
1459
1460 YoungList* young_list() { return _young_list; }
1461
1462 // debugging
1463 bool check_young_list_well_formed() {
1464 return _young_list->check_list_well_formed();
1465 }
1466
1467 bool check_young_list_empty(bool check_heap,
1468 bool check_sample = true);
1469
1470 // *** Stuff related to concurrent marking. It's not clear to me that so
1471 // many of these need to be public.
1472
1473 // The functions below are helper functions that a subclass of
1474 // "CollectedHeap" can use in the implementation of its virtual
1475 // functions.
1476 // This performs a concurrent marking of the live objects in a
1477 // bitmap off to the side.
1478 void doConcurrentMark();
1479
1480 bool isMarkedPrev(oop obj) const;
1481 bool isMarkedNext(oop obj) const;
1482
1483 // vo == UsePrevMarking -> use "prev" marking information,
1484 // vo == UseNextMarking -> use "next" marking information,
1485 // vo == UseMarkWord -> use mark word from object header
1486 bool is_obj_dead_cond(const oop obj,
1487 const HeapRegion* hr,
1488 const VerifyOption vo) const {
1489
1490 switch (vo) {
1491 case VerifyOption_G1UsePrevMarking:
1492 return is_obj_dead(obj, hr);
1493 case VerifyOption_G1UseNextMarking:
1494 return is_obj_ill(obj, hr);
1495 default:
1496 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1497 return !obj->is_gc_marked();
1498 }
1499 }
1500
1501 // Determine if an object is dead, given the object and also
1502 // the region to which the object belongs. An object is dead
1503 // iff a) it was not allocated since the last mark and b) it
1504 // is not marked.
1505
1506 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1507 return
1508 !hr->obj_allocated_since_prev_marking(obj) &&
1509 !isMarkedPrev(obj);
1510 }
1511
1512 // This is used when copying an object to survivor space.
1513 // If the object is marked live, then we mark the copy live.
1514 // If the object is allocated since the start of this mark
1515 // cycle, then we mark the copy live.
1516 // If the object has been around since the previous mark
1517 // phase, and hasn't been marked yet during this phase,
1518 // then we don't mark it, we just wait for the
1519 // current marking cycle to get to it.
1520
1521 // This function returns true when an object has been
1522 // around since the previous marking and hasn't yet
1523 // been marked during this marking.
1524
1525 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1526 return
1527 !hr->obj_allocated_since_next_marking(obj) &&
1528 !isMarkedNext(obj);
1529 }
1530
1531 // Determine if an object is dead, given only the object itself.
1532 // This will find the region to which the object belongs and
1533 // then call the region version of the same function.
1534
1535 // Added if it is in permanent gen it isn't dead.
1536 // Added if it is NULL it isn't dead.
1537
1538 // vo == UsePrevMarking -> use "prev" marking information,
1539 // vo == UseNextMarking -> use "next" marking information,
1540 // vo == UseMarkWord -> use mark word from object header
1541 bool is_obj_dead_cond(const oop obj,
1542 const VerifyOption vo) const {
1543
1544 switch (vo) {
1545 case VerifyOption_G1UsePrevMarking:
1546 return is_obj_dead(obj);
1547 case VerifyOption_G1UseNextMarking:
1548 return is_obj_ill(obj);
1549 default:
1550 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1551 return !obj->is_gc_marked();
1552 }
1553 }
1554
1555 bool is_obj_dead(const oop obj) const {
1556 const HeapRegion* hr = heap_region_containing(obj);
1557 if (hr == NULL) {
1558 if (Universe::heap()->is_in_permanent(obj))
1559 return false;
1560 else if (obj == NULL) return false;
1561 else return true;
1562 }
1563 else return is_obj_dead(obj, hr);
1564 }
1565
1566 bool is_obj_ill(const oop obj) const {
1567 const HeapRegion* hr = heap_region_containing(obj);
1568 if (hr == NULL) {
1569 if (Universe::heap()->is_in_permanent(obj))
1570 return false;
1571 else if (obj == NULL) return false;
1572 else return true;
1573 }
1574 else return is_obj_ill(obj, hr);
1575 }
1576
1577 // The following is just to alert the verification code
1578 // that a full collection has occurred and that the
1579 // remembered sets are no longer up to date.
1580 bool _full_collection;
1581 void set_full_collection() { _full_collection = true;}
1582 void clear_full_collection() {_full_collection = false;}
1583 bool full_collection() {return _full_collection;}
1584
1585 ConcurrentMark* concurrent_mark() const { return _cm; }
1586 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1587
1588 // The dirty cards region list is used to record a subset of regions
1589 // whose cards need clearing. The list if populated during the
1590 // remembered set scanning and drained during the card table
1591 // cleanup. Although the methods are reentrant, population/draining
1592 // phases must not overlap. For synchronization purposes the last
1593 // element on the list points to itself.
1594 HeapRegion* _dirty_cards_region_list;
1595 void push_dirty_cards_region(HeapRegion* hr);
1596 HeapRegion* pop_dirty_cards_region();
1597
1598 public:
1599 void stop_conc_gc_threads();
1600
1601 // <NEW PREDICTION>
1602
1603 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1604 void check_if_region_is_too_expensive(double predicted_time_ms);
1605 size_t pending_card_num();
1606 size_t max_pending_card_num();
1607 size_t cards_scanned();
1608
1609 // </NEW PREDICTION>
1610
1611 protected:
1612 size_t _max_heap_capacity;
1613 };
1614
1615 #define use_local_bitmaps 1
1616 #define verify_local_bitmaps 0
1617 #define oop_buffer_length 256
1618
1619 #ifndef PRODUCT
1620 class GCLabBitMap;
1621 class GCLabBitMapClosure: public BitMapClosure {
1622 private:
1623 ConcurrentMark* _cm;
1624 GCLabBitMap* _bitmap;
1625
1626 public:
1627 GCLabBitMapClosure(ConcurrentMark* cm,
1628 GCLabBitMap* bitmap) {
1629 _cm = cm;
1630 _bitmap = bitmap;
1631 }
1632
1633 virtual bool do_bit(size_t offset);
1634 };
1635 #endif // !PRODUCT
1636
1637 class GCLabBitMap: public BitMap {
1638 private:
1639 ConcurrentMark* _cm;
1640
1641 int _shifter;
1642 size_t _bitmap_word_covers_words;
1643
1644 // beginning of the heap
1645 HeapWord* _heap_start;
1646
1647 // this is the actual start of the GCLab
1648 HeapWord* _real_start_word;
1649
1650 // this is the actual end of the GCLab
1651 HeapWord* _real_end_word;
1652
1653 // this is the first word, possibly located before the actual start
1654 // of the GCLab, that corresponds to the first bit of the bitmap
1655 HeapWord* _start_word;
1656
1657 // size of a GCLab in words
1658 size_t _gclab_word_size;
1659
1660 static int shifter() {
1661 return MinObjAlignment - 1;
1662 }
1663
1664 // how many heap words does a single bitmap word corresponds to?
1665 static size_t bitmap_word_covers_words() {
1666 return BitsPerWord << shifter();
1667 }
1668
1669 size_t gclab_word_size() const {
1670 return _gclab_word_size;
1671 }
1672
1673 // Calculates actual GCLab size in words
1674 size_t gclab_real_word_size() const {
1675 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1676 / BitsPerWord;
1677 }
1678
1679 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1680 size_t bits_in_bitmap = gclab_word_size >> shifter();
1681 // We are going to ensure that the beginning of a word in this
1682 // bitmap also corresponds to the beginning of a word in the
1683 // global marking bitmap. To handle the case where a GCLab
1684 // starts from the middle of the bitmap, we need to add enough
1685 // space (i.e. up to a bitmap word) to ensure that we have
1686 // enough bits in the bitmap.
1687 return bits_in_bitmap + BitsPerWord - 1;
1688 }
1689 public:
1690 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1691 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1692 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1693 _shifter(shifter()),
1694 _bitmap_word_covers_words(bitmap_word_covers_words()),
1695 _heap_start(heap_start),
1696 _gclab_word_size(gclab_word_size),
1697 _real_start_word(NULL),
1698 _real_end_word(NULL),
1699 _start_word(NULL)
1700 {
1701 guarantee( size_in_words() >= bitmap_size_in_words(),
1702 "just making sure");
1703 }
1704
1705 inline unsigned heapWordToOffset(HeapWord* addr) {
1706 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1707 assert(offset < size(), "offset should be within bounds");
1708 return offset;
1709 }
1710
1711 inline HeapWord* offsetToHeapWord(size_t offset) {
1712 HeapWord* addr = _start_word + (offset << _shifter);
1713 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1714 return addr;
1715 }
1716
1717 bool fields_well_formed() {
1718 bool ret1 = (_real_start_word == NULL) &&
1719 (_real_end_word == NULL) &&
1720 (_start_word == NULL);
1721 if (ret1)
1722 return true;
1723
1724 bool ret2 = _real_start_word >= _start_word &&
1725 _start_word < _real_end_word &&
1726 (_real_start_word + _gclab_word_size) == _real_end_word &&
1727 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1728 > _real_end_word;
1729 return ret2;
1730 }
1731
1732 inline bool mark(HeapWord* addr) {
1733 guarantee(use_local_bitmaps, "invariant");
1734 assert(fields_well_formed(), "invariant");
1735
1736 if (addr >= _real_start_word && addr < _real_end_word) {
1737 assert(!isMarked(addr), "should not have already been marked");
1738
1739 // first mark it on the bitmap
1740 at_put(heapWordToOffset(addr), true);
1741
1742 return true;
1743 } else {
1744 return false;
1745 }
1746 }
1747
1748 inline bool isMarked(HeapWord* addr) {
1749 guarantee(use_local_bitmaps, "invariant");
1750 assert(fields_well_formed(), "invariant");
1751
1752 return at(heapWordToOffset(addr));
1753 }
1754
1755 void set_buffer(HeapWord* start) {
1756 guarantee(use_local_bitmaps, "invariant");
1757 clear();
1758
1759 assert(start != NULL, "invariant");
1760 _real_start_word = start;
1761 _real_end_word = start + _gclab_word_size;
1762
1763 size_t diff =
1764 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1765 _start_word = start - diff;
1766
1767 assert(fields_well_formed(), "invariant");
1768 }
1769
1770 #ifndef PRODUCT
1771 void verify() {
1772 // verify that the marks have been propagated
1773 GCLabBitMapClosure cl(_cm, this);
1774 iterate(&cl);
1775 }
1776 #endif // PRODUCT
1777
1778 void retire() {
1779 guarantee(use_local_bitmaps, "invariant");
1780 assert(fields_well_formed(), "invariant");
1781
1782 if (_start_word != NULL) {
1783 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1784
1785 // this means that the bitmap was set up for the GCLab
1786 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1787
1788 mark_bitmap->mostly_disjoint_range_union(this,
1789 0, // always start from the start of the bitmap
1790 _start_word,
1791 gclab_real_word_size());
1792 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1793
1794 #ifndef PRODUCT
1795 if (use_local_bitmaps && verify_local_bitmaps)
1796 verify();
1797 #endif // PRODUCT
1798 } else {
1799 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1800 }
1801 }
1802
1803 size_t bitmap_size_in_words() const {
1804 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1805 }
1806
1807 };
1808
1809 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1810 private:
1811 bool _retired;
1812 bool _should_mark_objects;
1813 GCLabBitMap _bitmap;
1814
1815 public:
1816 G1ParGCAllocBuffer(size_t gclab_word_size);
1817
1818 inline bool mark(HeapWord* addr) {
1819 guarantee(use_local_bitmaps, "invariant");
1820 assert(_should_mark_objects, "invariant");
1821 return _bitmap.mark(addr);
1822 }
1823
1824 inline void set_buf(HeapWord* buf) {
1825 if (use_local_bitmaps && _should_mark_objects) {
1826 _bitmap.set_buffer(buf);
1827 }
1828 ParGCAllocBuffer::set_buf(buf);
1829 _retired = false;
1830 }
1831
1832 inline void retire(bool end_of_gc, bool retain) {
1833 if (_retired)
1834 return;
1835 if (use_local_bitmaps && _should_mark_objects) {
1836 _bitmap.retire();
1837 }
1838 ParGCAllocBuffer::retire(end_of_gc, retain);
1839 _retired = true;
1840 }
1841 };
1842
1843 class G1ParScanThreadState : public StackObj {
1844 protected:
1845 G1CollectedHeap* _g1h;
1846 RefToScanQueue* _refs;
1847 DirtyCardQueue _dcq;
1848 CardTableModRefBS* _ct_bs;
1849 G1RemSet* _g1_rem;
1850
1851 G1ParGCAllocBuffer _surviving_alloc_buffer;
1852 G1ParGCAllocBuffer _tenured_alloc_buffer;
1853 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1854 ageTable _age_table;
1855
1856 size_t _alloc_buffer_waste;
1857 size_t _undo_waste;
1858
1859 OopsInHeapRegionClosure* _evac_failure_cl;
1860 G1ParScanHeapEvacClosure* _evac_cl;
1861 G1ParScanPartialArrayClosure* _partial_scan_cl;
1862
1863 int _hash_seed;
1864 int _queue_num;
1865
1866 size_t _term_attempts;
1867
1868 double _start;
1869 double _start_strong_roots;
1870 double _strong_roots_time;
1871 double _start_term;
1872 double _term_time;
1873
1874 // Map from young-age-index (0 == not young, 1 is youngest) to
1875 // surviving words. base is what we get back from the malloc call
1876 size_t* _surviving_young_words_base;
1877 // this points into the array, as we use the first few entries for padding
1878 size_t* _surviving_young_words;
1879
1880 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1881
1882 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1883
1884 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1885
1886 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1887 CardTableModRefBS* ctbs() { return _ct_bs; }
1888
1889 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1890 if (!from->is_survivor()) {
1891 _g1_rem->par_write_ref(from, p, tid);
1892 }
1893 }
1894
1895 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1896 // If the new value of the field points to the same region or
1897 // is the to-space, we don't need to include it in the Rset updates.
1898 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1899 size_t card_index = ctbs()->index_for(p);
1900 // If the card hasn't been added to the buffer, do it.
1901 if (ctbs()->mark_card_deferred(card_index)) {
1902 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1903 }
1904 }
1905 }
1906
1907 public:
1908 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1909
1910 ~G1ParScanThreadState() {
1911 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1912 }
1913
1914 RefToScanQueue* refs() { return _refs; }
1915 ageTable* age_table() { return &_age_table; }
1916
1917 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1918 return _alloc_buffers[purpose];
1919 }
1920
1921 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1922 size_t undo_waste() const { return _undo_waste; }
1923
1924 #ifdef ASSERT
1925 bool verify_ref(narrowOop* ref) const;
1926 bool verify_ref(oop* ref) const;
1927 bool verify_task(StarTask ref) const;
1928 #endif // ASSERT
1929
1930 template <class T> void push_on_queue(T* ref) {
1931 assert(verify_ref(ref), "sanity");
1932 refs()->push(ref);
1933 }
1934
1935 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1936 if (G1DeferredRSUpdate) {
1937 deferred_rs_update(from, p, tid);
1938 } else {
1939 immediate_rs_update(from, p, tid);
1940 }
1941 }
1942
1943 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1944
1945 HeapWord* obj = NULL;
1946 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1947 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1948 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1949 assert(gclab_word_size == alloc_buf->word_sz(),
1950 "dynamic resizing is not supported");
1951 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1952 alloc_buf->retire(false, false);
1953
1954 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1955 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1956 // Otherwise.
1957 alloc_buf->set_buf(buf);
1958
1959 obj = alloc_buf->allocate(word_sz);
1960 assert(obj != NULL, "buffer was definitely big enough...");
1961 } else {
1962 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1963 }
1964 return obj;
1965 }
1966
1967 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1968 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1969 if (obj != NULL) return obj;
1970 return allocate_slow(purpose, word_sz);
1971 }
1972
1973 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1974 if (alloc_buffer(purpose)->contains(obj)) {
1975 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1976 "should contain whole object");
1977 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1978 } else {
1979 CollectedHeap::fill_with_object(obj, word_sz);
1980 add_to_undo_waste(word_sz);
1981 }
1982 }
1983
1984 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1985 _evac_failure_cl = evac_failure_cl;
1986 }
1987 OopsInHeapRegionClosure* evac_failure_closure() {
1988 return _evac_failure_cl;
1989 }
1990
1991 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1992 _evac_cl = evac_cl;
1993 }
1994
1995 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1996 _partial_scan_cl = partial_scan_cl;
1997 }
1998
1999 int* hash_seed() { return &_hash_seed; }
2000 int queue_num() { return _queue_num; }
2001
2002 size_t term_attempts() const { return _term_attempts; }
2003 void note_term_attempt() { _term_attempts++; }
2004
2005 void start_strong_roots() {
2006 _start_strong_roots = os::elapsedTime();
2007 }
2008 void end_strong_roots() {
2009 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2010 }
2011 double strong_roots_time() const { return _strong_roots_time; }
2012
2013 void start_term_time() {
2014 note_term_attempt();
2015 _start_term = os::elapsedTime();
2016 }
2017 void end_term_time() {
2018 _term_time += (os::elapsedTime() - _start_term);
2019 }
2020 double term_time() const { return _term_time; }
2021
2022 double elapsed_time() const {
2023 return os::elapsedTime() - _start;
2024 }
2025
2026 static void
2027 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2028 void
2029 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2030
2031 size_t* surviving_young_words() {
2032 // We add on to hide entry 0 which accumulates surviving words for
2033 // age -1 regions (i.e. non-young ones)
2034 return _surviving_young_words;
2035 }
2036
2037 void retire_alloc_buffers() {
2038 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2039 size_t waste = _alloc_buffers[ap]->words_remaining();
2040 add_to_alloc_buffer_waste(waste);
2041 _alloc_buffers[ap]->retire(true, false);
2042 }
2043 }
2044
2045 template <class T> void deal_with_reference(T* ref_to_scan) {
2046 if (has_partial_array_mask(ref_to_scan)) {
2047 _partial_scan_cl->do_oop_nv(ref_to_scan);
2048 } else {
2049 // Note: we can use "raw" versions of "region_containing" because
2050 // "obj_to_scan" is definitely in the heap, and is not in a
2051 // humongous region.
2052 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2053 _evac_cl->set_region(r);
2054 _evac_cl->do_oop_nv(ref_to_scan);
2055 }
2056 }
2057
2058 void deal_with_reference(StarTask ref) {
2059 assert(verify_task(ref), "sanity");
2060 if (ref.is_narrow()) {
2061 deal_with_reference((narrowOop*)ref);
2062 } else {
2063 deal_with_reference((oop*)ref);
2064 }
2065 }
2066
2067 public:
2068 void trim_queue();
2069 };
2070
2071 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP