1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
8 *
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/concurrentMark.hpp"
29 #include "gc/g1/evacuationInfo.hpp"
30 #include "gc/g1/g1AllocationContext.hpp"
31 #include "gc/g1/g1BiasedArray.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1HRPrinter.hpp"
34 #include "gc/g1/g1InCSetState.hpp"
35 #include "gc/g1/g1MonitoringSupport.hpp"
36 #include "gc/g1/g1EvacStats.hpp"
37 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
38 #include "gc/g1/g1YCTypes.hpp"
39 #include "gc/g1/hSpaceCounters.hpp"
40 #include "gc/g1/heapRegionManager.hpp"
41 #include "gc/g1/heapRegionSet.hpp"
42 #include "gc/shared/barrierSet.hpp"
43 #include "gc/shared/collectedHeap.hpp"
44 #include "gc/shared/plab.hpp"
45 #include "memory/memRegion.hpp"
46 #include "utilities/stack.hpp"
47
48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
49 // It uses the "Garbage First" heap organization and algorithm, which
50 // may combine concurrent marking with parallel, incremental compaction of
51 // heap subsets that will yield large amounts of garbage.
52
53 // Forward declarations
54 class HeapRegion;
55 class HRRSCleanupTask;
56 class GenerationSpec;
57 class OopsInHeapRegionClosure;
58 class G1ParScanThreadState;
59 class G1KlassScanClosure;
60 class G1ParScanThreadState;
61 class ObjectClosure;
62 class SpaceClosure;
63 class CompactibleSpaceClosure;
64 class Space;
65 class G1CollectorPolicy;
66 class GenRemSet;
67 class G1RemSet;
68 class HeapRegionRemSetIterator;
69 class ConcurrentMark;
70 class ConcurrentMarkThread;
71 class ConcurrentG1Refine;
72 class ConcurrentGCTimer;
73 class GenerationCounters;
74 class STWGCTimer;
75 class G1NewTracer;
76 class G1OldTracer;
77 class EvacuationFailedInfo;
78 class nmethod;
79 class Ticks;
80 class FlexibleWorkGang;
81 class G1Allocator;
82 class G1ArchiveAllocator;
83
84 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
85 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
86
87 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
88 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
89
90 class YoungList : public CHeapObj<mtGC> {
91 private:
92 G1CollectedHeap* _g1h;
93
94 HeapRegion* _head;
95
96 HeapRegion* _survivor_head;
97 HeapRegion* _survivor_tail;
98
99 HeapRegion* _curr;
100
101 uint _length;
102 uint _survivor_length;
103
104 size_t _last_sampled_rs_lengths;
105 size_t _sampled_rs_lengths;
106
107 void empty_list(HeapRegion* list);
108
109 public:
110 YoungList(G1CollectedHeap* g1h);
111
112 void push_region(HeapRegion* hr);
113 void add_survivor_region(HeapRegion* hr);
114
115 void empty_list();
116 bool is_empty() { return _length == 0; }
117 uint length() { return _length; }
118 uint eden_length() { return length() - survivor_length(); }
119 uint survivor_length() { return _survivor_length; }
120
121 // Currently we do not keep track of the used byte sum for the
122 // young list and the survivors and it'd be quite a lot of work to
123 // do so. When we'll eventually replace the young list with
124 // instances of HeapRegionLinkedList we'll get that for free. So,
125 // we'll report the more accurate information then.
126 size_t eden_used_bytes() {
127 assert(length() >= survivor_length(), "invariant");
128 return (size_t) eden_length() * HeapRegion::GrainBytes;
129 }
130 size_t survivor_used_bytes() {
131 return (size_t) survivor_length() * HeapRegion::GrainBytes;
132 }
133
134 void rs_length_sampling_init();
135 bool rs_length_sampling_more();
136 void rs_length_sampling_next();
137
138 void reset_sampled_info() {
139 _last_sampled_rs_lengths = 0;
140 }
141 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
142
143 // for development purposes
144 void reset_auxilary_lists();
145 void clear() { _head = NULL; _length = 0; }
146
147 void clear_survivors() {
148 _survivor_head = NULL;
149 _survivor_tail = NULL;
150 _survivor_length = 0;
151 }
152
153 HeapRegion* first_region() { return _head; }
154 HeapRegion* first_survivor_region() { return _survivor_head; }
155 HeapRegion* last_survivor_region() { return _survivor_tail; }
156
157 // debugging
158 bool check_list_well_formed();
159 bool check_list_empty(bool check_sample = true);
160 void print();
161 };
162
163 // The G1 STW is alive closure.
164 // An instance is embedded into the G1CH and used as the
165 // (optional) _is_alive_non_header closure in the STW
166 // reference processor. It is also extensively used during
167 // reference processing during STW evacuation pauses.
168 class G1STWIsAliveClosure: public BoolObjectClosure {
169 G1CollectedHeap* _g1;
170 public:
171 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
172 bool do_object_b(oop p);
173 };
174
175 class RefineCardTableEntryClosure;
176
177 class G1RegionMappingChangedListener : public G1MappingChangedListener {
178 private:
179 void reset_from_card_cache(uint start_idx, size_t num_regions);
180 public:
181 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
182 };
183
184 class G1CollectedHeap : public CollectedHeap {
185 friend class VM_CollectForMetadataAllocation;
186 friend class VM_G1CollectForAllocation;
187 friend class VM_G1CollectFull;
188 friend class VM_G1IncCollectionPause;
189 friend class VMStructs;
190 friend class MutatorAllocRegion;
191 friend class G1GCAllocRegion;
192
193 // Closures used in implementation.
194 friend class G1ParScanThreadState;
195 friend class G1ParTask;
196 friend class G1PLABAllocator;
197 friend class G1PrepareCompactClosure;
198
199 // Other related classes.
200 friend class HeapRegionClaimer;
201
202 // Testing classes.
203 friend class G1CheckCSetFastTableClosure;
204
205 private:
206 FlexibleWorkGang* _workers;
207
208 static size_t _humongous_object_threshold_in_words;
209
210 // The secondary free list which contains regions that have been
211 // freed up during the cleanup process. This will be appended to
212 // the master free list when appropriate.
213 FreeRegionList _secondary_free_list;
214
215 // It keeps track of the old regions.
216 HeapRegionSet _old_set;
217
218 // It keeps track of the humongous regions.
219 HeapRegionSet _humongous_set;
220
221 void eagerly_reclaim_humongous_regions();
222
223 // The number of regions we could create by expansion.
224 uint _expansion_regions;
225
226 // The block offset table for the G1 heap.
227 G1BlockOffsetSharedArray* _bot_shared;
228
229 // Tears down the region sets / lists so that they are empty and the
230 // regions on the heap do not belong to a region set / list. The
231 // only exception is the humongous set which we leave unaltered. If
232 // free_list_only is true, it will only tear down the master free
233 // list. It is called before a Full GC (free_list_only == false) or
234 // before heap shrinking (free_list_only == true).
235 void tear_down_region_sets(bool free_list_only);
236
237 // Rebuilds the region sets / lists so that they are repopulated to
238 // reflect the contents of the heap. The only exception is the
239 // humongous set which was not torn down in the first place. If
240 // free_list_only is true, it will only rebuild the master free
241 // list. It is called after a Full GC (free_list_only == false) or
242 // after heap shrinking (free_list_only == true).
243 void rebuild_region_sets(bool free_list_only);
244
245 // Callback for region mapping changed events.
246 G1RegionMappingChangedListener _listener;
247
248 // The sequence of all heap regions in the heap.
249 HeapRegionManager _hrm;
250
251 // Manages all allocations with regions except humongous object allocations.
252 G1Allocator* _allocator;
253
254 // Outside of GC pauses, the number of bytes used in all regions other
255 // than the current allocation region(s).
256 size_t _summary_bytes_used;
257
258 void increase_used(size_t bytes);
259 void decrease_used(size_t bytes);
260
261 void set_used(size_t bytes);
262
263 // Class that handles archive allocation ranges.
264 G1ArchiveAllocator* _archive_allocator;
265
266 // Statistics for each allocation context
267 AllocationContextStats _allocation_context_stats;
268
269 // GC allocation statistics policy for survivors.
270 G1EvacStats _survivor_evac_stats;
271
272 // GC allocation statistics policy for tenured objects.
273 G1EvacStats _old_evac_stats;
274
275 // It specifies whether we should attempt to expand the heap after a
276 // region allocation failure. If heap expansion fails we set this to
277 // false so that we don't re-attempt the heap expansion (it's likely
278 // that subsequent expansion attempts will also fail if one fails).
279 // Currently, it is only consulted during GC and it's reset at the
280 // start of each GC.
281 bool _expand_heap_after_alloc_failure;
282
283 // Helper for monitoring and management support.
284 G1MonitoringSupport* _g1mm;
285
286 // Records whether the region at the given index is (still) a
287 // candidate for eager reclaim. Only valid for humongous start
288 // regions; other regions have unspecified values. Humongous start
289 // regions are initialized at start of collection pause, with
290 // candidates removed from the set as they are found reachable from
291 // roots or the young generation.
292 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
293 protected:
294 bool default_value() const { return false; }
295 public:
296 void clear() { G1BiasedMappedArray<bool>::clear(); }
297 void set_candidate(uint region, bool value) {
298 set_by_index(region, value);
299 }
300 bool is_candidate(uint region) {
301 return get_by_index(region);
302 }
303 };
304
305 HumongousReclaimCandidates _humongous_reclaim_candidates;
306 // Stores whether during humongous object registration we found candidate regions.
307 // If not, we can skip a few steps.
308 bool _has_humongous_reclaim_candidates;
309
310 volatile unsigned _gc_time_stamp;
311
312 size_t* _surviving_young_words;
313
314 G1HRPrinter _hr_printer;
315
316 void setup_surviving_young_words();
317 void update_surviving_young_words(size_t* surv_young_words);
318 void cleanup_surviving_young_words();
319
320 // It decides whether an explicit GC should start a concurrent cycle
321 // instead of doing a STW GC. Currently, a concurrent cycle is
322 // explicitly started if:
323 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
324 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
325 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
326 // (d) cause == _g1_humongous_allocation
327 bool should_do_concurrent_full_gc(GCCause::Cause cause);
328
329 // indicates whether we are in young or mixed GC mode
330 G1CollectorState _collector_state;
331
332 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
333 // concurrent cycles) we have started.
334 volatile uint _old_marking_cycles_started;
335
336 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
337 // concurrent cycles) we have completed.
338 volatile uint _old_marking_cycles_completed;
339
340 bool _heap_summary_sent;
341
342 // This is a non-product method that is helpful for testing. It is
343 // called at the end of a GC and artificially expands the heap by
344 // allocating a number of dead regions. This way we can induce very
345 // frequent marking cycles and stress the cleanup / concurrent
346 // cleanup code more (as all the regions that will be allocated by
347 // this method will be found dead by the marking cycle).
348 void allocate_dummy_regions() PRODUCT_RETURN;
349
350 // Clear RSets after a compaction. It also resets the GC time stamps.
351 void clear_rsets_post_compaction();
352
353 // If the HR printer is active, dump the state of the regions in the
354 // heap after a compaction.
355 void print_hrm_post_compaction();
356
357 // Create a memory mapper for auxiliary data structures of the given size and
358 // translation factor.
359 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
360 size_t size,
361 size_t translation_factor);
362
363 double verify(bool guard, const char* msg);
364 void verify_before_gc();
365 void verify_after_gc();
366
367 void log_gc_header();
368 void log_gc_footer(double pause_time_sec);
369
370 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
371
372 // These are macros so that, if the assert fires, we get the correct
373 // line number, file, etc.
374
375 #define heap_locking_asserts_err_msg(_extra_message_) \
376 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
377 (_extra_message_), \
378 BOOL_TO_STR(Heap_lock->owned_by_self()), \
379 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
380 BOOL_TO_STR(Thread::current()->is_VM_thread()))
381
382 #define assert_heap_locked() \
383 do { \
384 assert(Heap_lock->owned_by_self(), \
385 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
386 } while (0)
387
388 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
389 do { \
390 assert(Heap_lock->owned_by_self() || \
391 (SafepointSynchronize::is_at_safepoint() && \
392 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
393 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
394 "should be at a safepoint")); \
395 } while (0)
396
397 #define assert_heap_locked_and_not_at_safepoint() \
398 do { \
399 assert(Heap_lock->owned_by_self() && \
400 !SafepointSynchronize::is_at_safepoint(), \
401 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
402 "should not be at a safepoint")); \
403 } while (0)
404
405 #define assert_heap_not_locked() \
406 do { \
407 assert(!Heap_lock->owned_by_self(), \
408 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
409 } while (0)
410
411 #define assert_heap_not_locked_and_not_at_safepoint() \
412 do { \
413 assert(!Heap_lock->owned_by_self() && \
414 !SafepointSynchronize::is_at_safepoint(), \
415 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
416 "should not be at a safepoint")); \
417 } while (0)
418
419 #define assert_at_safepoint(_should_be_vm_thread_) \
420 do { \
421 assert(SafepointSynchronize::is_at_safepoint() && \
422 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
423 heap_locking_asserts_err_msg("should be at a safepoint")); \
424 } while (0)
425
426 #define assert_not_at_safepoint() \
427 do { \
428 assert(!SafepointSynchronize::is_at_safepoint(), \
429 heap_locking_asserts_err_msg("should not be at a safepoint")); \
430 } while (0)
431
432 protected:
433
434 // The young region list.
435 YoungList* _young_list;
436
437 // The current policy object for the collector.
438 G1CollectorPolicy* _g1_policy;
439
440 // This is the second level of trying to allocate a new region. If
441 // new_region() didn't find a region on the free_list, this call will
442 // check whether there's anything available on the
443 // secondary_free_list and/or wait for more regions to appear on
444 // that list, if _free_regions_coming is set.
445 HeapRegion* new_region_try_secondary_free_list(bool is_old);
446
447 // Try to allocate a single non-humongous HeapRegion sufficient for
448 // an allocation of the given word_size. If do_expand is true,
449 // attempt to expand the heap if necessary to satisfy the allocation
450 // request. If the region is to be used as an old region or for a
451 // humongous object, set is_old to true. If not, to false.
452 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
453
454 // Initialize a contiguous set of free regions of length num_regions
455 // and starting at index first so that they appear as a single
456 // humongous region.
457 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
458 uint num_regions,
459 size_t word_size,
460 AllocationContext_t context);
461
462 // Attempt to allocate a humongous object of the given size. Return
463 // NULL if unsuccessful.
464 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
465
466 // The following two methods, allocate_new_tlab() and
467 // mem_allocate(), are the two main entry points from the runtime
468 // into the G1's allocation routines. They have the following
469 // assumptions:
470 //
471 // * They should both be called outside safepoints.
472 //
473 // * They should both be called without holding the Heap_lock.
474 //
475 // * All allocation requests for new TLABs should go to
476 // allocate_new_tlab().
477 //
478 // * All non-TLAB allocation requests should go to mem_allocate().
479 //
480 // * If either call cannot satisfy the allocation request using the
481 // current allocating region, they will try to get a new one. If
482 // this fails, they will attempt to do an evacuation pause and
483 // retry the allocation.
484 //
485 // * If all allocation attempts fail, even after trying to schedule
486 // an evacuation pause, allocate_new_tlab() will return NULL,
487 // whereas mem_allocate() will attempt a heap expansion and/or
488 // schedule a Full GC.
489 //
490 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
491 // should never be called with word_size being humongous. All
492 // humongous allocation requests should go to mem_allocate() which
493 // will satisfy them with a special path.
494
495 virtual HeapWord* allocate_new_tlab(size_t word_size);
496
497 virtual HeapWord* mem_allocate(size_t word_size,
498 bool* gc_overhead_limit_was_exceeded);
499
500 // The following three methods take a gc_count_before_ret
501 // parameter which is used to return the GC count if the method
502 // returns NULL. Given that we are required to read the GC count
503 // while holding the Heap_lock, and these paths will take the
504 // Heap_lock at some point, it's easier to get them to read the GC
505 // count while holding the Heap_lock before they return NULL instead
506 // of the caller (namely: mem_allocate()) having to also take the
507 // Heap_lock just to read the GC count.
508
509 // First-level mutator allocation attempt: try to allocate out of
510 // the mutator alloc region without taking the Heap_lock. This
511 // should only be used for non-humongous allocations.
512 inline HeapWord* attempt_allocation(size_t word_size,
513 uint* gc_count_before_ret,
514 uint* gclocker_retry_count_ret);
515
516 // Second-level mutator allocation attempt: take the Heap_lock and
517 // retry the allocation attempt, potentially scheduling a GC
518 // pause. This should only be used for non-humongous allocations.
519 HeapWord* attempt_allocation_slow(size_t word_size,
520 AllocationContext_t context,
521 uint* gc_count_before_ret,
522 uint* gclocker_retry_count_ret);
523
524 // Takes the Heap_lock and attempts a humongous allocation. It can
525 // potentially schedule a GC pause.
526 HeapWord* attempt_allocation_humongous(size_t word_size,
527 uint* gc_count_before_ret,
528 uint* gclocker_retry_count_ret);
529
530 // Allocation attempt that should be called during safepoints (e.g.,
531 // at the end of a successful GC). expect_null_mutator_alloc_region
532 // specifies whether the mutator alloc region is expected to be NULL
533 // or not.
534 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
535 AllocationContext_t context,
536 bool expect_null_mutator_alloc_region);
537
538 // These methods are the "callbacks" from the G1AllocRegion class.
539
540 // For mutator alloc regions.
541 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
542 void retire_mutator_alloc_region(HeapRegion* alloc_region,
543 size_t allocated_bytes);
544
545 // For GC alloc regions.
546 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
547 InCSetState dest);
548 void retire_gc_alloc_region(HeapRegion* alloc_region,
549 size_t allocated_bytes, InCSetState dest);
550
551 // - if explicit_gc is true, the GC is for a System.gc() or a heap
552 // inspection request and should collect the entire heap
553 // - if clear_all_soft_refs is true, all soft references should be
554 // cleared during the GC
555 // - if explicit_gc is false, word_size describes the allocation that
556 // the GC should attempt (at least) to satisfy
557 // - it returns false if it is unable to do the collection due to the
558 // GC locker being active, true otherwise
559 bool do_collection(bool explicit_gc,
560 bool clear_all_soft_refs,
561 size_t word_size);
562
563 // Callback from VM_G1CollectFull operation.
564 // Perform a full collection.
565 virtual void do_full_collection(bool clear_all_soft_refs);
566
567 // Resize the heap if necessary after a full collection. If this is
568 // after a collect-for allocation, "word_size" is the allocation size,
569 // and will be considered part of the used portion of the heap.
570 void resize_if_necessary_after_full_collection(size_t word_size);
571
572 // Callback from VM_G1CollectForAllocation operation.
573 // This function does everything necessary/possible to satisfy a
574 // failed allocation request (including collection, expansion, etc.)
575 HeapWord* satisfy_failed_allocation(size_t word_size,
576 AllocationContext_t context,
577 bool* succeeded);
578
579 // Attempting to expand the heap sufficiently
580 // to support an allocation of the given "word_size". If
581 // successful, perform the allocation and return the address of the
582 // allocated block, or else "NULL".
583 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
584
585 // Process any reference objects discovered during
586 // an incremental evacuation pause.
587 void process_discovered_references(G1ParScanThreadState** pss);
588
589 // Enqueue any remaining discovered references
590 // after processing.
591 void enqueue_discovered_references(G1ParScanThreadState** pss);
592
593 public:
594 FlexibleWorkGang* workers() const { return _workers; }
595
596 G1Allocator* allocator() {
597 return _allocator;
598 }
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 // Returns the PLAB statistics for a given destination.
612 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
613
614 // Determines PLAB size for a given destination.
615 inline size_t desired_plab_sz(InCSetState dest);
616
617 inline AllocationContextStats& allocation_context_stats();
618
619 // Do anything common to GC's.
620 void gc_prologue(bool full);
621 void gc_epilogue(bool full);
622
623 // Modify the reclaim candidate set and test for presence.
624 // These are only valid for starts_humongous regions.
625 inline void set_humongous_reclaim_candidate(uint region, bool value);
626 inline bool is_humongous_reclaim_candidate(uint region);
627
628 // Remove from the reclaim candidate set. Also remove from the
629 // collection set so that later encounters avoid the slow path.
630 inline void set_humongous_is_live(oop obj);
631
632 // Register the given region to be part of the collection set.
633 inline void register_humongous_region_with_cset(uint index);
634 // Register regions with humongous objects (actually on the start region) in
635 // the in_cset_fast_test table.
636 void register_humongous_regions_with_cset();
637 // We register a region with the fast "in collection set" test. We
638 // simply set to true the array slot corresponding to this region.
639 void register_young_region_with_cset(HeapRegion* r) {
640 _in_cset_fast_test.set_in_young(r->hrm_index());
641 }
642 void register_old_region_with_cset(HeapRegion* r) {
643 _in_cset_fast_test.set_in_old(r->hrm_index());
644 }
645 void clear_in_cset(const HeapRegion* hr) {
646 _in_cset_fast_test.clear(hr);
647 }
648
649 void clear_cset_fast_test() {
650 _in_cset_fast_test.clear();
651 }
652
653 // This is called at the start of either a concurrent cycle or a Full
654 // GC to update the number of old marking cycles started.
655 void increment_old_marking_cycles_started();
656
657 // This is called at the end of either a concurrent cycle or a Full
658 // GC to update the number of old marking cycles completed. Those two
659 // can happen in a nested fashion, i.e., we start a concurrent
660 // cycle, a Full GC happens half-way through it which ends first,
661 // and then the cycle notices that a Full GC happened and ends
662 // too. The concurrent parameter is a boolean to help us do a bit
663 // tighter consistency checking in the method. If concurrent is
664 // false, the caller is the inner caller in the nesting (i.e., the
665 // Full GC). If concurrent is true, the caller is the outer caller
666 // in this nesting (i.e., the concurrent cycle). Further nesting is
667 // not currently supported. The end of this call also notifies
668 // the FullGCCount_lock in case a Java thread is waiting for a full
669 // GC to happen (e.g., it called System.gc() with
670 // +ExplicitGCInvokesConcurrent).
671 void increment_old_marking_cycles_completed(bool concurrent);
672
673 uint old_marking_cycles_completed() {
674 return _old_marking_cycles_completed;
675 }
676
677 void register_concurrent_cycle_start(const Ticks& start_time);
678 void register_concurrent_cycle_end();
679 void trace_heap_after_concurrent_cycle();
680
681 G1HRPrinter* hr_printer() { return &_hr_printer; }
682
683 // Allocates a new heap region instance.
684 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
685
686 // Allocates a new per thread par scan state for the given thread id.
687 G1ParScanThreadState* new_par_scan_state(uint worker_id);
688
689 // Allocate the highest free region in the reserved heap. This will commit
690 // regions as necessary.
691 HeapRegion* alloc_highest_free_region();
692
693 // Frees a non-humongous region by initializing its contents and
694 // adding it to the free list that's passed as a parameter (this is
695 // usually a local list which will be appended to the master free
696 // list later). The used bytes of freed regions are accumulated in
697 // pre_used. If par is true, the region's RSet will not be freed
698 // up. The assumption is that this will be done later.
699 // The locked parameter indicates if the caller has already taken
700 // care of proper synchronization. This may allow some optimizations.
701 void free_region(HeapRegion* hr,
702 FreeRegionList* free_list,
703 bool par,
704 bool locked = false);
705
706 // It dirties the cards that cover the block so that the post
707 // write barrier never queues anything when updating objects on this
708 // block. It is assumed (and in fact we assert) that the block
709 // belongs to a young region.
710 inline void dirty_young_block(HeapWord* start, size_t word_size);
711
712 // Frees a humongous region by collapsing it into individual regions
713 // and calling free_region() for each of them. The freed regions
714 // will be added to the free list that's passed as a parameter (this
715 // is usually a local list which will be appended to the master free
716 // list later). The used bytes of freed regions are accumulated in
717 // pre_used. If par is true, the region's RSet will not be freed
718 // up. The assumption is that this will be done later.
719 void free_humongous_region(HeapRegion* hr,
720 FreeRegionList* free_list,
721 bool par);
722
723 // Facility for allocating in 'archive' regions in high heap memory and
724 // recording the allocated ranges. These should all be called from the
725 // VM thread at safepoints, without the heap lock held. They can be used
726 // to create and archive a set of heap regions which can be mapped at the
727 // same fixed addresses in a subsequent JVM invocation.
728 void begin_archive_alloc_range();
729
730 // Check if the requested size would be too large for an archive allocation.
731 bool is_archive_alloc_too_large(size_t word_size);
732
733 // Allocate memory of the requested size from the archive region. This will
734 // return NULL if the size is too large or if no memory is available. It
735 // does not trigger a garbage collection.
736 HeapWord* archive_mem_allocate(size_t word_size);
737
738 // Optionally aligns the end address and returns the allocated ranges in
739 // an array of MemRegions in order of ascending addresses.
740 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
741 size_t end_alignment_in_bytes = 0);
742
743 // Facility for allocating a fixed range within the heap and marking
744 // the containing regions as 'archive'. For use at JVM init time, when the
745 // caller may mmap archived heap data at the specified range(s).
746 // Verify that the MemRegions specified in the argument array are within the
747 // reserved heap.
748 bool check_archive_addresses(MemRegion* range, size_t count);
749
750 // Commit the appropriate G1 regions containing the specified MemRegions
751 // and mark them as 'archive' regions. The regions in the array must be
752 // non-overlapping and in order of ascending address.
753 bool alloc_archive_regions(MemRegion* range, size_t count);
754
755 // Insert any required filler objects in the G1 regions around the specified
756 // ranges to make the regions parseable. This must be called after
757 // alloc_archive_regions, and after class loading has occurred.
758 void fill_archive_regions(MemRegion* range, size_t count);
759
760 protected:
761
762 // Shrink the garbage-first heap by at most the given size (in bytes!).
763 // (Rounds down to a HeapRegion boundary.)
764 virtual void shrink(size_t expand_bytes);
765 void shrink_helper(size_t expand_bytes);
766
767 #if TASKQUEUE_STATS
768 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
769 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
770 void reset_taskqueue_stats();
771 #endif // TASKQUEUE_STATS
772
773 // Schedule the VM operation that will do an evacuation pause to
774 // satisfy an allocation request of word_size. *succeeded will
775 // return whether the VM operation was successful (it did do an
776 // evacuation pause) or not (another thread beat us to it or the GC
777 // locker was active). Given that we should not be holding the
778 // Heap_lock when we enter this method, we will pass the
779 // gc_count_before (i.e., total_collections()) as a parameter since
780 // it has to be read while holding the Heap_lock. Currently, both
781 // methods that call do_collection_pause() release the Heap_lock
782 // before the call, so it's easy to read gc_count_before just before.
783 HeapWord* do_collection_pause(size_t word_size,
784 uint gc_count_before,
785 bool* succeeded,
786 GCCause::Cause gc_cause);
787
788 void wait_for_root_region_scanning();
789
790 // The guts of the incremental collection pause, executed by the vm
791 // thread. It returns false if it is unable to do the collection due
792 // to the GC locker being active, true otherwise
793 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
794
795 // Actually do the work of evacuating the collection set.
796 void evacuate_collection_set(EvacuationInfo& evacuation_info);
797
798 // Print the header for the per-thread termination statistics.
799 static void print_termination_stats_hdr(outputStream* const st);
800 // Print actual per-thread termination statistics.
801 void print_termination_stats(outputStream* const st,
802 uint worker_id,
803 double elapsed_ms,
804 double strong_roots_ms,
805 double term_ms,
806 size_t term_attempts,
807 size_t alloc_buffer_waste,
808 size_t undo_waste) const;
809 // Update object copying statistics.
810 void record_obj_copy_mem_stats();
811
812 // The g1 remembered set of the heap.
813 G1RemSet* _g1_rem_set;
814
815 // A set of cards that cover the objects for which the Rsets should be updated
816 // concurrently after the collection.
817 DirtyCardQueueSet _dirty_card_queue_set;
818
819 // The closure used to refine a single card.
820 RefineCardTableEntryClosure* _refine_cte_cl;
821
822 // A DirtyCardQueueSet that is used to hold cards that contain
823 // references into the current collection set. This is used to
824 // update the remembered sets of the regions in the collection
825 // set in the event of an evacuation failure.
826 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
827
828 // After a collection pause, make the regions in the CS into free
829 // regions.
830 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
831
832 // Abandon the current collection set without recording policy
833 // statistics or updating free lists.
834 void abandon_collection_set(HeapRegion* cs_head);
835
836 // The concurrent marker (and the thread it runs in.)
837 ConcurrentMark* _cm;
838 ConcurrentMarkThread* _cmThread;
839
840 // The concurrent refiner.
841 ConcurrentG1Refine* _cg1r;
842
843 // The parallel task queues
844 RefToScanQueueSet *_task_queues;
845
846 // True iff a evacuation has failed in the current collection.
847 bool _evacuation_failed;
848
849 EvacuationFailedInfo* _evacuation_failed_info_array;
850
851 // Failed evacuations cause some logical from-space objects to have
852 // forwarding pointers to themselves. Reset them.
853 void remove_self_forwarding_pointers();
854
855 struct OopAndMarkOop {
856 private:
857 oop _o;
858 markOop _m;
859 public:
860 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) {
861 }
862
863 void set_mark() {
864 _o->set_mark(_m);
865 }
866 };
867
868 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack;
869 // Stores marks with the corresponding oop that we need to preserve during evacuation
870 // failure.
871 OopAndMarkOopStack* _preserved_objs;
872
873 // Preserve the mark of "obj", if necessary, in preparation for its mark
874 // word being overwritten with a self-forwarding-pointer.
875 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
876
877 #ifndef PRODUCT
878 // Support for forcing evacuation failures. Analogous to
879 // PromotionFailureALot for the other collectors.
880
881 // Records whether G1EvacuationFailureALot should be in effect
882 // for the current GC
883 bool _evacuation_failure_alot_for_current_gc;
884
885 // Used to record the GC number for interval checking when
886 // determining whether G1EvaucationFailureALot is in effect
887 // for the current GC.
888 size_t _evacuation_failure_alot_gc_number;
889
890 // Count of the number of evacuations between failures.
891 volatile size_t _evacuation_failure_alot_count;
892
893 // Set whether G1EvacuationFailureALot should be in effect
894 // for the current GC (based upon the type of GC and which
895 // command line flags are set);
896 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
897 bool during_initial_mark,
898 bool during_marking);
899
900 inline void set_evacuation_failure_alot_for_current_gc();
901
902 // Return true if it's time to cause an evacuation failure.
903 inline bool evacuation_should_fail();
904
905 // Reset the G1EvacuationFailureALot counters. Should be called at
906 // the end of an evacuation pause in which an evacuation failure occurred.
907 inline void reset_evacuation_should_fail();
908 #endif // !PRODUCT
909
910 // ("Weak") Reference processing support.
911 //
912 // G1 has 2 instances of the reference processor class. One
913 // (_ref_processor_cm) handles reference object discovery
914 // and subsequent processing during concurrent marking cycles.
915 //
916 // The other (_ref_processor_stw) handles reference object
917 // discovery and processing during full GCs and incremental
918 // evacuation pauses.
919 //
920 // During an incremental pause, reference discovery will be
921 // temporarily disabled for _ref_processor_cm and will be
922 // enabled for _ref_processor_stw. At the end of the evacuation
923 // pause references discovered by _ref_processor_stw will be
924 // processed and discovery will be disabled. The previous
925 // setting for reference object discovery for _ref_processor_cm
926 // will be re-instated.
927 //
928 // At the start of marking:
929 // * Discovery by the CM ref processor is verified to be inactive
930 // and it's discovered lists are empty.
931 // * Discovery by the CM ref processor is then enabled.
932 //
933 // At the end of marking:
934 // * Any references on the CM ref processor's discovered
935 // lists are processed (possibly MT).
936 //
937 // At the start of full GC we:
938 // * Disable discovery by the CM ref processor and
939 // empty CM ref processor's discovered lists
940 // (without processing any entries).
941 // * Verify that the STW ref processor is inactive and it's
942 // discovered lists are empty.
943 // * Temporarily set STW ref processor discovery as single threaded.
944 // * Temporarily clear the STW ref processor's _is_alive_non_header
945 // field.
946 // * Finally enable discovery by the STW ref processor.
947 //
948 // The STW ref processor is used to record any discovered
949 // references during the full GC.
950 //
951 // At the end of a full GC we:
952 // * Enqueue any reference objects discovered by the STW ref processor
953 // that have non-live referents. This has the side-effect of
954 // making the STW ref processor inactive by disabling discovery.
955 // * Verify that the CM ref processor is still inactive
956 // and no references have been placed on it's discovered
957 // lists (also checked as a precondition during initial marking).
958
959 // The (stw) reference processor...
960 ReferenceProcessor* _ref_processor_stw;
961
962 STWGCTimer* _gc_timer_stw;
963 ConcurrentGCTimer* _gc_timer_cm;
964
965 G1OldTracer* _gc_tracer_cm;
966 G1NewTracer* _gc_tracer_stw;
967
968 // During reference object discovery, the _is_alive_non_header
969 // closure (if non-null) is applied to the referent object to
970 // determine whether the referent is live. If so then the
971 // reference object does not need to be 'discovered' and can
972 // be treated as a regular oop. This has the benefit of reducing
973 // the number of 'discovered' reference objects that need to
974 // be processed.
975 //
976 // Instance of the is_alive closure for embedding into the
977 // STW reference processor as the _is_alive_non_header field.
978 // Supplying a value for the _is_alive_non_header field is
979 // optional but doing so prevents unnecessary additions to
980 // the discovered lists during reference discovery.
981 G1STWIsAliveClosure _is_alive_closure_stw;
982
983 // The (concurrent marking) reference processor...
984 ReferenceProcessor* _ref_processor_cm;
985
986 // Instance of the concurrent mark is_alive closure for embedding
987 // into the Concurrent Marking reference processor as the
988 // _is_alive_non_header field. Supplying a value for the
989 // _is_alive_non_header field is optional but doing so prevents
990 // unnecessary additions to the discovered lists during reference
991 // discovery.
992 G1CMIsAliveClosure _is_alive_closure_cm;
993
994 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
995 HeapRegion** _worker_cset_start_region;
996
997 // Time stamp to validate the regions recorded in the cache
998 // used by G1CollectedHeap::start_cset_region_for_worker().
999 // The heap region entry for a given worker is valid iff
1000 // the associated time stamp value matches the current value
1001 // of G1CollectedHeap::_gc_time_stamp.
1002 uint* _worker_cset_start_region_time_stamp;
1003
1004 volatile bool _free_regions_coming;
1005
1006 public:
1007
1008 void set_refine_cte_cl_concurrency(bool concurrent);
1009
1010 RefToScanQueue *task_queue(uint i) const;
1011
1012 uint num_task_queues() const;
1013
1014 // A set of cards where updates happened during the GC
1015 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1016
1017 // A DirtyCardQueueSet that is used to hold cards that contain
1018 // references into the current collection set. This is used to
1019 // update the remembered sets of the regions in the collection
1020 // set in the event of an evacuation failure.
1021 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1022 { return _into_cset_dirty_card_queue_set; }
1023
1024 // Create a G1CollectedHeap with the specified policy.
1025 // Must call the initialize method afterwards.
1026 // May not return if something goes wrong.
1027 G1CollectedHeap(G1CollectorPolicy* policy);
1028
1029 // Initialize the G1CollectedHeap to have the initial and
1030 // maximum sizes and remembered and barrier sets
1031 // specified by the policy object.
1032 jint initialize();
1033
1034 virtual void stop();
1035
1036 // Return the (conservative) maximum heap alignment for any G1 heap
1037 static size_t conservative_max_heap_alignment();
1038
1039 // Does operations required after initialization has been done.
1040 void post_initialize();
1041
1042 // Initialize weak reference processing.
1043 void ref_processing_init();
1044
1045 virtual Name kind() const {
1046 return CollectedHeap::G1CollectedHeap;
1047 }
1048
1049 G1CollectorState* collector_state() { return &_collector_state; }
1050
1051 // The current policy object for the collector.
1052 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1053
1054 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1055
1056 // Adaptive size policy. No such thing for g1.
1057 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1058
1059 // The rem set and barrier set.
1060 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1061
1062 unsigned get_gc_time_stamp() {
1063 return _gc_time_stamp;
1064 }
1065
1066 inline void reset_gc_time_stamp();
1067
1068 void check_gc_time_stamps() PRODUCT_RETURN;
1069
1070 inline void increment_gc_time_stamp();
1071
1072 // Reset the given region's GC timestamp. If it's starts humongous,
1073 // also reset the GC timestamp of its corresponding
1074 // continues humongous regions too.
1075 void reset_gc_time_stamps(HeapRegion* hr);
1076
1077 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1078 DirtyCardQueue* into_cset_dcq,
1079 bool concurrent, uint worker_i);
1080
1081 // The shared block offset table array.
1082 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1083
1084 // Reference Processing accessors
1085
1086 // The STW reference processor....
1087 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1088
1089 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1090
1091 // The Concurrent Marking reference processor...
1092 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1093
1094 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1095 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1096
1097 virtual size_t capacity() const;
1098 virtual size_t used() const;
1099 // This should be called when we're not holding the heap lock. The
1100 // result might be a bit inaccurate.
1101 size_t used_unlocked() const;
1102 size_t recalculate_used() const;
1103
1104 // These virtual functions do the actual allocation.
1105 // Some heaps may offer a contiguous region for shared non-blocking
1106 // allocation, via inlined code (by exporting the address of the top and
1107 // end fields defining the extent of the contiguous allocation region.)
1108 // But G1CollectedHeap doesn't yet support this.
1109
1110 virtual bool is_maximal_no_gc() const {
1111 return _hrm.available() == 0;
1112 }
1113
1114 // The current number of regions in the heap.
1115 uint num_regions() const { return _hrm.length(); }
1116
1117 // The max number of regions in the heap.
1118 uint max_regions() const { return _hrm.max_length(); }
1119
1120 // The number of regions that are completely free.
1121 uint num_free_regions() const { return _hrm.num_free_regions(); }
1122
1123 MemoryUsage get_auxiliary_data_memory_usage() const {
1124 return _hrm.get_auxiliary_data_memory_usage();
1125 }
1126
1127 // The number of regions that are not completely free.
1128 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1129
1130 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1131 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1132 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1133 void verify_dirty_young_regions() PRODUCT_RETURN;
1134
1135 #ifndef PRODUCT
1136 // Make sure that the given bitmap has no marked objects in the
1137 // range [from,limit). If it does, print an error message and return
1138 // false. Otherwise, just return true. bitmap_name should be "prev"
1139 // or "next".
1140 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1141 HeapWord* from, HeapWord* limit);
1142
1143 // Verify that the prev / next bitmap range [tams,end) for the given
1144 // region has no marks. Return true if all is well, false if errors
1145 // are detected.
1146 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1147 #endif // PRODUCT
1148
1149 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1150 // the given region do not have any spurious marks. If errors are
1151 // detected, print appropriate error messages and crash.
1152 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1153
1154 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1155 // have any spurious marks. If errors are detected, print
1156 // appropriate error messages and crash.
1157 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1158
1159 // Do sanity check on the contents of the in-cset fast test table.
1160 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1161
1162 // verify_region_sets() performs verification over the region
1163 // lists. It will be compiled in the product code to be used when
1164 // necessary (i.e., during heap verification).
1165 void verify_region_sets();
1166
1167 // verify_region_sets_optional() is planted in the code for
1168 // list verification in non-product builds (and it can be enabled in
1169 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1170 #if HEAP_REGION_SET_FORCE_VERIFY
1171 void verify_region_sets_optional() {
1172 verify_region_sets();
1173 }
1174 #else // HEAP_REGION_SET_FORCE_VERIFY
1175 void verify_region_sets_optional() { }
1176 #endif // HEAP_REGION_SET_FORCE_VERIFY
1177
1178 #ifdef ASSERT
1179 bool is_on_master_free_list(HeapRegion* hr) {
1180 return _hrm.is_free(hr);
1181 }
1182 #endif // ASSERT
1183
1184 // Wrapper for the region list operations that can be called from
1185 // methods outside this class.
1186
1187 void secondary_free_list_add(FreeRegionList* list) {
1188 _secondary_free_list.add_ordered(list);
1189 }
1190
1191 void append_secondary_free_list() {
1192 _hrm.insert_list_into_free_list(&_secondary_free_list);
1193 }
1194
1195 void append_secondary_free_list_if_not_empty_with_lock() {
1196 // If the secondary free list looks empty there's no reason to
1197 // take the lock and then try to append it.
1198 if (!_secondary_free_list.is_empty()) {
1199 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1200 append_secondary_free_list();
1201 }
1202 }
1203
1204 inline void old_set_add(HeapRegion* hr);
1205 inline void old_set_remove(HeapRegion* hr);
1206
1207 size_t non_young_capacity_bytes() {
1208 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1209 }
1210
1211 void set_free_regions_coming();
1212 void reset_free_regions_coming();
1213 bool free_regions_coming() { return _free_regions_coming; }
1214 void wait_while_free_regions_coming();
1215
1216 // Determine whether the given region is one that we are using as an
1217 // old GC alloc region.
1218 bool is_old_gc_alloc_region(HeapRegion* hr);
1219
1220 // Perform a collection of the heap; intended for use in implementing
1221 // "System.gc". This probably implies as full a collection as the
1222 // "CollectedHeap" supports.
1223 virtual void collect(GCCause::Cause cause);
1224
1225 // The same as above but assume that the caller holds the Heap_lock.
1226 void collect_locked(GCCause::Cause cause);
1227
1228 virtual bool copy_allocation_context_stats(const jint* contexts,
1229 jlong* totals,
1230 jbyte* accuracy,
1231 jint len);
1232
1233 // True iff an evacuation has failed in the most-recent collection.
1234 bool evacuation_failed() { return _evacuation_failed; }
1235
1236 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1237 void prepend_to_freelist(FreeRegionList* list);
1238 void decrement_summary_bytes(size_t bytes);
1239
1240 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1241 virtual bool is_in(const void* p) const;
1242 #ifdef ASSERT
1243 // Returns whether p is in one of the available areas of the heap. Slow but
1244 // extensive version.
1245 bool is_in_exact(const void* p) const;
1246 #endif
1247
1248 // Return "TRUE" iff the given object address is within the collection
1249 // set. Slow implementation.
1250 bool obj_in_cs(oop obj);
1251
1252 inline bool is_in_cset(const HeapRegion *hr);
1253 inline bool is_in_cset(oop obj);
1254
1255 inline bool is_in_cset_or_humongous(const oop obj);
1256
1257 private:
1258 // This array is used for a quick test on whether a reference points into
1259 // the collection set or not. Each of the array's elements denotes whether the
1260 // corresponding region is in the collection set or not.
1261 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1262
1263 public:
1264
1265 inline InCSetState in_cset_state(const oop obj);
1266
1267 // Return "TRUE" iff the given object address is in the reserved
1268 // region of g1.
1269 bool is_in_g1_reserved(const void* p) const {
1270 return _hrm.reserved().contains(p);
1271 }
1272
1273 // Returns a MemRegion that corresponds to the space that has been
1274 // reserved for the heap
1275 MemRegion g1_reserved() const {
1276 return _hrm.reserved();
1277 }
1278
1279 virtual bool is_in_closed_subset(const void* p) const;
1280
1281 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1282 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1283 }
1284
1285 // This resets the card table to all zeros. It is used after
1286 // a collection pause which used the card table to claim cards.
1287 void cleanUpCardTable();
1288
1289 // Iteration functions.
1290
1291 // Iterate over all objects, calling "cl.do_object" on each.
1292 virtual void object_iterate(ObjectClosure* cl);
1293
1294 virtual void safe_object_iterate(ObjectClosure* cl) {
1295 object_iterate(cl);
1296 }
1297
1298 // Iterate over heap regions, in address order, terminating the
1299 // iteration early if the "doHeapRegion" method returns "true".
1300 void heap_region_iterate(HeapRegionClosure* blk) const;
1301
1302 // Return the region with the given index. It assumes the index is valid.
1303 inline HeapRegion* region_at(uint index) const;
1304
1305 // Calculate the region index of the given address. Given address must be
1306 // within the heap.
1307 inline uint addr_to_region(HeapWord* addr) const;
1308
1309 inline HeapWord* bottom_addr_for_region(uint index) const;
1310
1311 // Iterate over the heap regions in parallel. Assumes that this will be called
1312 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1313 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1314 // to each of the regions, by attempting to claim the region using the
1315 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1316 // region. The concurrent argument should be set to true if iteration is
1317 // performed concurrently, during which no assumptions are made for consistent
1318 // attributes of the heap regions (as they might be modified while iterating).
1319 void heap_region_par_iterate(HeapRegionClosure* cl,
1320 uint worker_id,
1321 HeapRegionClaimer* hrclaimer,
1322 bool concurrent = false) const;
1323
1324 // Clear the cached cset start regions and (more importantly)
1325 // the time stamps. Called when we reset the GC time stamp.
1326 void clear_cset_start_regions();
1327
1328 // Given the id of a worker, obtain or calculate a suitable
1329 // starting region for iterating over the current collection set.
1330 HeapRegion* start_cset_region_for_worker(uint worker_i);
1331
1332 // Iterate over the regions (if any) in the current collection set.
1333 void collection_set_iterate(HeapRegionClosure* blk);
1334
1335 // As above but starting from region r
1336 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1337
1338 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1339
1340 // Returns the HeapRegion that contains addr. addr must not be NULL.
1341 template <class T>
1342 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1343
1344 // Returns the HeapRegion that contains addr. addr must not be NULL.
1345 // If addr is within a humongous continues region, it returns its humongous start region.
1346 template <class T>
1347 inline HeapRegion* heap_region_containing(const T addr) const;
1348
1349 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1350 // each address in the (reserved) heap is a member of exactly
1351 // one block. The defining characteristic of a block is that it is
1352 // possible to find its size, and thus to progress forward to the next
1353 // block. (Blocks may be of different sizes.) Thus, blocks may
1354 // represent Java objects, or they might be free blocks in a
1355 // free-list-based heap (or subheap), as long as the two kinds are
1356 // distinguishable and the size of each is determinable.
1357
1358 // Returns the address of the start of the "block" that contains the
1359 // address "addr". We say "blocks" instead of "object" since some heaps
1360 // may not pack objects densely; a chunk may either be an object or a
1361 // non-object.
1362 virtual HeapWord* block_start(const void* addr) const;
1363
1364 // Requires "addr" to be the start of a chunk, and returns its size.
1365 // "addr + size" is required to be the start of a new chunk, or the end
1366 // of the active area of the heap.
1367 virtual size_t block_size(const HeapWord* addr) const;
1368
1369 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1370 // the block is an object.
1371 virtual bool block_is_obj(const HeapWord* addr) const;
1372
1373 // Section on thread-local allocation buffers (TLABs)
1374 // See CollectedHeap for semantics.
1375
1376 bool supports_tlab_allocation() const;
1377 size_t tlab_capacity(Thread* ignored) const;
1378 size_t tlab_used(Thread* ignored) const;
1379 size_t max_tlab_size() const;
1380 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1381
1382 // Can a compiler initialize a new object without store barriers?
1383 // This permission only extends from the creation of a new object
1384 // via a TLAB up to the first subsequent safepoint. If such permission
1385 // is granted for this heap type, the compiler promises to call
1386 // defer_store_barrier() below on any slow path allocation of
1387 // a new object for which such initializing store barriers will
1388 // have been elided. G1, like CMS, allows this, but should be
1389 // ready to provide a compensating write barrier as necessary
1390 // if that storage came out of a non-young region. The efficiency
1391 // of this implementation depends crucially on being able to
1392 // answer very efficiently in constant time whether a piece of
1393 // storage in the heap comes from a young region or not.
1394 // See ReduceInitialCardMarks.
1395 virtual bool can_elide_tlab_store_barriers() const {
1396 return true;
1397 }
1398
1399 virtual bool card_mark_must_follow_store() const {
1400 return true;
1401 }
1402
1403 inline bool is_in_young(const oop obj);
1404
1405 virtual bool is_scavengable(const void* addr);
1406
1407 // We don't need barriers for initializing stores to objects
1408 // in the young gen: for the SATB pre-barrier, there is no
1409 // pre-value that needs to be remembered; for the remembered-set
1410 // update logging post-barrier, we don't maintain remembered set
1411 // information for young gen objects.
1412 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1413
1414 // Returns "true" iff the given word_size is "very large".
1415 static bool is_humongous(size_t word_size) {
1416 // Note this has to be strictly greater-than as the TLABs
1417 // are capped at the humongous threshold and we want to
1418 // ensure that we don't try to allocate a TLAB as
1419 // humongous and that we don't allocate a humongous
1420 // object in a TLAB.
1421 return word_size > _humongous_object_threshold_in_words;
1422 }
1423
1424 // Returns the humongous threshold for a specific region size
1425 static size_t humongous_threshold_for(size_t region_size) {
1426 return (region_size / 2);
1427 }
1428
1429 // Update mod union table with the set of dirty cards.
1430 void updateModUnion();
1431
1432 // Set the mod union bits corresponding to the given memRegion. Note
1433 // that this is always a safe operation, since it doesn't clear any
1434 // bits.
1435 void markModUnionRange(MemRegion mr);
1436
1437 // Print the maximum heap capacity.
1438 virtual size_t max_capacity() const;
1439
1440 virtual jlong millis_since_last_gc();
1441
1442
1443 // Convenience function to be used in situations where the heap type can be
1444 // asserted to be this type.
1445 static G1CollectedHeap* heap();
1446
1447 void set_region_short_lived_locked(HeapRegion* hr);
1448 // add appropriate methods for any other surv rate groups
1449
1450 YoungList* young_list() const { return _young_list; }
1451
1452 // debugging
1453 bool check_young_list_well_formed() {
1454 return _young_list->check_list_well_formed();
1455 }
1456
1457 bool check_young_list_empty(bool check_heap,
1458 bool check_sample = true);
1459
1460 // *** Stuff related to concurrent marking. It's not clear to me that so
1461 // many of these need to be public.
1462
1463 // The functions below are helper functions that a subclass of
1464 // "CollectedHeap" can use in the implementation of its virtual
1465 // functions.
1466 // This performs a concurrent marking of the live objects in a
1467 // bitmap off to the side.
1468 void doConcurrentMark();
1469
1470 bool isMarkedPrev(oop obj) const;
1471 bool isMarkedNext(oop obj) const;
1472
1473 // Determine if an object is dead, given the object and also
1474 // the region to which the object belongs. An object is dead
1475 // iff a) it was not allocated since the last mark, b) it
1476 // is not marked, and c) it is not in an archive region.
1477 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1478 return
1479 !hr->obj_allocated_since_prev_marking(obj) &&
1480 !isMarkedPrev(obj) &&
1481 !hr->is_archive();
1482 }
1483
1484 // This function returns true when an object has been
1485 // around since the previous marking and hasn't yet
1486 // been marked during this marking, and is not in an archive region.
1487 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1488 return
1489 !hr->obj_allocated_since_next_marking(obj) &&
1490 !isMarkedNext(obj) &&
1491 !hr->is_archive();
1492 }
1493
1494 // Determine if an object is dead, given only the object itself.
1495 // This will find the region to which the object belongs and
1496 // then call the region version of the same function.
1497
1498 // Added if it is NULL it isn't dead.
1499
1500 inline bool is_obj_dead(const oop obj) const;
1501
1502 inline bool is_obj_ill(const oop obj) const;
1503
1504 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1505 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1506 bool is_marked(oop obj, VerifyOption vo);
1507 const char* top_at_mark_start_str(VerifyOption vo);
1508
1509 ConcurrentMark* concurrent_mark() const { return _cm; }
1510
1511 // Refinement
1512
1513 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1514
1515 // The dirty cards region list is used to record a subset of regions
1516 // whose cards need clearing. The list if populated during the
1517 // remembered set scanning and drained during the card table
1518 // cleanup. Although the methods are reentrant, population/draining
1519 // phases must not overlap. For synchronization purposes the last
1520 // element on the list points to itself.
1521 HeapRegion* _dirty_cards_region_list;
1522 void push_dirty_cards_region(HeapRegion* hr);
1523 HeapRegion* pop_dirty_cards_region();
1524
1525 // Optimized nmethod scanning support routines
1526
1527 // Register the given nmethod with the G1 heap.
1528 virtual void register_nmethod(nmethod* nm);
1529
1530 // Unregister the given nmethod from the G1 heap.
1531 virtual void unregister_nmethod(nmethod* nm);
1532
1533 // Free up superfluous code root memory.
1534 void purge_code_root_memory();
1535
1536 // Rebuild the strong code root lists for each region
1537 // after a full GC.
1538 void rebuild_strong_code_roots();
1539
1540 // Delete entries for dead interned string and clean up unreferenced symbols
1541 // in symbol table, possibly in parallel.
1542 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1543
1544 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1545 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1546
1547 // Redirty logged cards in the refinement queue.
1548 void redirty_logged_cards();
1549 // Verification
1550
1551 // Perform any cleanup actions necessary before allowing a verification.
1552 virtual void prepare_for_verify();
1553
1554 // Perform verification.
1555
1556 // vo == UsePrevMarking -> use "prev" marking information,
1557 // vo == UseNextMarking -> use "next" marking information
1558 // vo == UseMarkWord -> use the mark word in the object header
1559 //
1560 // NOTE: Only the "prev" marking information is guaranteed to be
1561 // consistent most of the time, so most calls to this should use
1562 // vo == UsePrevMarking.
1563 // Currently, there is only one case where this is called with
1564 // vo == UseNextMarking, which is to verify the "next" marking
1565 // information at the end of remark.
1566 // Currently there is only one place where this is called with
1567 // vo == UseMarkWord, which is to verify the marking during a
1568 // full GC.
1569 void verify(bool silent, VerifyOption vo);
1570
1571 // Override; it uses the "prev" marking information
1572 virtual void verify(bool silent);
1573
1574 // The methods below are here for convenience and dispatch the
1575 // appropriate method depending on value of the given VerifyOption
1576 // parameter. The values for that parameter, and their meanings,
1577 // are the same as those above.
1578
1579 bool is_obj_dead_cond(const oop obj,
1580 const HeapRegion* hr,
1581 const VerifyOption vo) const;
1582
1583 bool is_obj_dead_cond(const oop obj,
1584 const VerifyOption vo) const;
1585
1586 G1HeapSummary create_g1_heap_summary();
1587 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1588
1589 // Printing
1590
1591 virtual void print_on(outputStream* st) const;
1592 virtual void print_extended_on(outputStream* st) const;
1593 virtual void print_on_error(outputStream* st) const;
1594
1595 virtual void print_gc_threads_on(outputStream* st) const;
1596 virtual void gc_threads_do(ThreadClosure* tc) const;
1597
1598 // Override
1599 void print_tracing_info() const;
1600
1601 // The following two methods are helpful for debugging RSet issues.
1602 void print_cset_rsets() PRODUCT_RETURN;
1603 void print_all_rsets() PRODUCT_RETURN;
1604
1605 public:
1606 size_t pending_card_num();
1607 size_t cards_scanned();
1608
1609 protected:
1610 size_t _max_heap_capacity;
1611 };
1612
1613 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP