Tue, 01 Mar 2011 14:56:48 -0800
6627983: G1: Bad oop deference during marking
Summary: Bulk zeroing reduction didn't work with G1, because arraycopy would call pre-barriers on uninitialized oops. The solution is to have version of arraycopy stubs that don't have pre-barriers. Also refactored arraycopy stubs generation on SPARC to be more readable and reduced the number of stubs necessary in some cases.
Reviewed-by: jrose, kvn, never
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1RemSet.hpp"
30 #include "gc_implementation/g1/heapRegionSets.hpp"
31 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
32 #include "memory/barrierSet.hpp"
33 #include "memory/memRegion.hpp"
34 #include "memory/sharedHeap.hpp"
36 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
37 // It uses the "Garbage First" heap organization and algorithm, which
38 // may combine concurrent marking with parallel, incremental compaction of
39 // heap subsets that will yield large amounts of garbage.
41 class HeapRegion;
42 class HeapRegionSeq;
43 class HRRSCleanupTask;
44 class PermanentGenerationSpec;
45 class GenerationSpec;
46 class OopsInHeapRegionClosure;
47 class G1ScanHeapEvacClosure;
48 class ObjectClosure;
49 class SpaceClosure;
50 class CompactibleSpaceClosure;
51 class Space;
52 class G1CollectorPolicy;
53 class GenRemSet;
54 class G1RemSet;
55 class HeapRegionRemSetIterator;
56 class ConcurrentMark;
57 class ConcurrentMarkThread;
58 class ConcurrentG1Refine;
59 class ConcurrentZFThread;
61 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
62 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
64 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
65 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
67 enum G1GCThreadGroups {
68 G1CRGroup = 0,
69 G1ZFGroup = 1,
70 G1CMGroup = 2
71 };
73 enum GCAllocPurpose {
74 GCAllocForTenured,
75 GCAllocForSurvived,
76 GCAllocPurposeCount
77 };
79 class YoungList : public CHeapObj {
80 private:
81 G1CollectedHeap* _g1h;
83 HeapRegion* _head;
85 HeapRegion* _survivor_head;
86 HeapRegion* _survivor_tail;
88 HeapRegion* _curr;
90 size_t _length;
91 size_t _survivor_length;
93 size_t _last_sampled_rs_lengths;
94 size_t _sampled_rs_lengths;
96 void empty_list(HeapRegion* list);
98 public:
99 YoungList(G1CollectedHeap* g1h);
101 void push_region(HeapRegion* hr);
102 void add_survivor_region(HeapRegion* hr);
104 void empty_list();
105 bool is_empty() { return _length == 0; }
106 size_t length() { return _length; }
107 size_t survivor_length() { return _survivor_length; }
109 void rs_length_sampling_init();
110 bool rs_length_sampling_more();
111 void rs_length_sampling_next();
113 void reset_sampled_info() {
114 _last_sampled_rs_lengths = 0;
115 }
116 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
118 // for development purposes
119 void reset_auxilary_lists();
120 void clear() { _head = NULL; _length = 0; }
122 void clear_survivors() {
123 _survivor_head = NULL;
124 _survivor_tail = NULL;
125 _survivor_length = 0;
126 }
128 HeapRegion* first_region() { return _head; }
129 HeapRegion* first_survivor_region() { return _survivor_head; }
130 HeapRegion* last_survivor_region() { return _survivor_tail; }
132 // debugging
133 bool check_list_well_formed();
134 bool check_list_empty(bool check_sample = true);
135 void print();
136 };
138 class RefineCardTableEntryClosure;
139 class G1CollectedHeap : public SharedHeap {
140 friend class VM_G1CollectForAllocation;
141 friend class VM_GenCollectForPermanentAllocation;
142 friend class VM_G1CollectFull;
143 friend class VM_G1IncCollectionPause;
144 friend class VMStructs;
146 // Closures used in implementation.
147 friend class G1ParCopyHelper;
148 friend class G1IsAliveClosure;
149 friend class G1EvacuateFollowersClosure;
150 friend class G1ParScanThreadState;
151 friend class G1ParScanClosureSuper;
152 friend class G1ParEvacuateFollowersClosure;
153 friend class G1ParTask;
154 friend class G1FreeGarbageRegionClosure;
155 friend class RefineCardTableEntryClosure;
156 friend class G1PrepareCompactClosure;
157 friend class RegionSorter;
158 friend class RegionResetter;
159 friend class CountRCClosure;
160 friend class EvacPopObjClosure;
161 friend class G1ParCleanupCTTask;
163 // Other related classes.
164 friend class G1MarkSweep;
166 private:
167 // The one and only G1CollectedHeap, so static functions can find it.
168 static G1CollectedHeap* _g1h;
170 static size_t _humongous_object_threshold_in_words;
172 // Storage for the G1 heap (excludes the permanent generation).
173 VirtualSpace _g1_storage;
174 MemRegion _g1_reserved;
176 // The part of _g1_storage that is currently committed.
177 MemRegion _g1_committed;
179 // The maximum part of _g1_storage that has ever been committed.
180 MemRegion _g1_max_committed;
182 // The master free list. It will satisfy all new region allocations.
183 MasterFreeRegionList _free_list;
185 // The secondary free list which contains regions that have been
186 // freed up during the cleanup process. This will be appended to the
187 // master free list when appropriate.
188 SecondaryFreeRegionList _secondary_free_list;
190 // It keeps track of the humongous regions.
191 MasterHumongousRegionSet _humongous_set;
193 // The number of regions we could create by expansion.
194 size_t _expansion_regions;
196 // The block offset table for the G1 heap.
197 G1BlockOffsetSharedArray* _bot_shared;
199 // Move all of the regions off the free lists, then rebuild those free
200 // lists, before and after full GC.
201 void tear_down_region_lists();
202 void rebuild_region_lists();
204 // The sequence of all heap regions in the heap.
205 HeapRegionSeq* _hrs;
207 // The region from which normal-sized objects are currently being
208 // allocated. May be NULL.
209 HeapRegion* _cur_alloc_region;
211 // Postcondition: cur_alloc_region == NULL.
212 void abandon_cur_alloc_region();
213 void abandon_gc_alloc_regions();
215 // The to-space memory regions into which objects are being copied during
216 // a GC.
217 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
218 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
219 // These are the regions, one per GCAllocPurpose, that are half-full
220 // at the end of a collection and that we want to reuse during the
221 // next collection.
222 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
223 // This specifies whether we will keep the last half-full region at
224 // the end of a collection so that it can be reused during the next
225 // collection (this is specified per GCAllocPurpose)
226 bool _retain_gc_alloc_region[GCAllocPurposeCount];
228 // A list of the regions that have been set to be alloc regions in the
229 // current collection.
230 HeapRegion* _gc_alloc_region_list;
232 // Determines PLAB size for a particular allocation purpose.
233 static size_t desired_plab_sz(GCAllocPurpose purpose);
235 // When called by par thread, requires the FreeList_lock to be held.
236 void push_gc_alloc_region(HeapRegion* hr);
238 // This should only be called single-threaded. Undeclares all GC alloc
239 // regions.
240 void forget_alloc_region_list();
242 // Should be used to set an alloc region, because there's other
243 // associated bookkeeping.
244 void set_gc_alloc_region(int purpose, HeapRegion* r);
246 // Check well-formedness of alloc region list.
247 bool check_gc_alloc_regions();
249 // Outside of GC pauses, the number of bytes used in all regions other
250 // than the current allocation region.
251 size_t _summary_bytes_used;
253 // This is used for a quick test on whether a reference points into
254 // the collection set or not. Basically, we have an array, with one
255 // byte per region, and that byte denotes whether the corresponding
256 // region is in the collection set or not. The entry corresponding
257 // the bottom of the heap, i.e., region 0, is pointed to by
258 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
259 // biased so that it actually points to address 0 of the address
260 // space, to make the test as fast as possible (we can simply shift
261 // the address to address into it, instead of having to subtract the
262 // bottom of the heap from the address before shifting it; basically
263 // it works in the same way the card table works).
264 bool* _in_cset_fast_test;
266 // The allocated array used for the fast test on whether a reference
267 // points into the collection set or not. This field is also used to
268 // free the array.
269 bool* _in_cset_fast_test_base;
271 // The length of the _in_cset_fast_test_base array.
272 size_t _in_cset_fast_test_length;
274 volatile unsigned _gc_time_stamp;
276 size_t* _surviving_young_words;
278 void setup_surviving_young_words();
279 void update_surviving_young_words(size_t* surv_young_words);
280 void cleanup_surviving_young_words();
282 // It decides whether an explicit GC should start a concurrent cycle
283 // instead of doing a STW GC. Currently, a concurrent cycle is
284 // explicitly started if:
285 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
286 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
287 bool should_do_concurrent_full_gc(GCCause::Cause cause);
289 // Keeps track of how many "full collections" (i.e., Full GCs or
290 // concurrent cycles) we have completed. The number of them we have
291 // started is maintained in _total_full_collections in CollectedHeap.
292 volatile unsigned int _full_collections_completed;
294 // These are macros so that, if the assert fires, we get the correct
295 // line number, file, etc.
297 #define heap_locking_asserts_err_msg(__extra_message) \
298 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
299 (__extra_message), \
300 BOOL_TO_STR(Heap_lock->owned_by_self()), \
301 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
302 BOOL_TO_STR(Thread::current()->is_VM_thread()))
304 #define assert_heap_locked() \
305 do { \
306 assert(Heap_lock->owned_by_self(), \
307 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
308 } while (0)
310 #define assert_heap_locked_or_at_safepoint(__should_be_vm_thread) \
311 do { \
312 assert(Heap_lock->owned_by_self() || \
313 (SafepointSynchronize::is_at_safepoint() && \
314 ((__should_be_vm_thread) == Thread::current()->is_VM_thread())), \
315 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
316 "should be at a safepoint")); \
317 } while (0)
319 #define assert_heap_locked_and_not_at_safepoint() \
320 do { \
321 assert(Heap_lock->owned_by_self() && \
322 !SafepointSynchronize::is_at_safepoint(), \
323 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
324 "should not be at a safepoint")); \
325 } while (0)
327 #define assert_heap_not_locked() \
328 do { \
329 assert(!Heap_lock->owned_by_self(), \
330 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
331 } while (0)
333 #define assert_heap_not_locked_and_not_at_safepoint() \
334 do { \
335 assert(!Heap_lock->owned_by_self() && \
336 !SafepointSynchronize::is_at_safepoint(), \
337 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
338 "should not be at a safepoint")); \
339 } while (0)
341 #define assert_at_safepoint(__should_be_vm_thread) \
342 do { \
343 assert(SafepointSynchronize::is_at_safepoint() && \
344 ((__should_be_vm_thread) == Thread::current()->is_VM_thread()), \
345 heap_locking_asserts_err_msg("should be at a safepoint")); \
346 } while (0)
348 #define assert_not_at_safepoint() \
349 do { \
350 assert(!SafepointSynchronize::is_at_safepoint(), \
351 heap_locking_asserts_err_msg("should not be at a safepoint")); \
352 } while (0)
354 protected:
356 // Returns "true" iff none of the gc alloc regions have any allocations
357 // since the last call to "save_marks".
358 bool all_alloc_regions_no_allocs_since_save_marks();
359 // Perform finalization stuff on all allocation regions.
360 void retire_all_alloc_regions();
362 // The number of regions allocated to hold humongous objects.
363 int _num_humongous_regions;
364 YoungList* _young_list;
366 // The current policy object for the collector.
367 G1CollectorPolicy* _g1_policy;
369 // This is the second level of trying to allocate a new region. If
370 // new_region_work didn't find a region in the free_list, this call
371 // will check whether there's anything available in the
372 // secondary_free_list and/or wait for more regions to appear in that
373 // list, if _free_regions_coming is set.
374 HeapRegion* new_region_try_secondary_free_list(size_t word_size);
376 // It will try to allocate a single non-humongous HeapRegion
377 // sufficient for an allocation of the given word_size. If
378 // do_expand is true, it will attempt to expand the heap if
379 // necessary to satisfy the allocation request. Note that word_size
380 // is only used to make sure that we expand sufficiently but, given
381 // that the allocation request is assumed not to be humongous,
382 // having word_size is not strictly necessary (expanding by a single
383 // region will always be sufficient). But let's keep that parameter
384 // in case we need it in the future.
385 HeapRegion* new_region_work(size_t word_size, bool do_expand);
387 // It will try to allocate a new region to be used for allocation by
388 // mutator threads. It will not try to expand the heap if not region
389 // is available.
390 HeapRegion* new_alloc_region(size_t word_size) {
391 return new_region_work(word_size, false /* do_expand */);
392 }
394 // It will try to allocate a new region to be used for allocation by
395 // a GC thread. It will try to expand the heap if no region is
396 // available.
397 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
399 int humongous_obj_allocate_find_first(size_t num_regions, size_t word_size);
401 // Attempt to allocate an object of the given (very large) "word_size".
402 // Returns "NULL" on failure.
403 HeapWord* humongous_obj_allocate(size_t word_size);
405 // The following two methods, allocate_new_tlab() and
406 // mem_allocate(), are the two main entry points from the runtime
407 // into the G1's allocation routines. They have the following
408 // assumptions:
409 //
410 // * They should both be called outside safepoints.
411 //
412 // * They should both be called without holding the Heap_lock.
413 //
414 // * All allocation requests for new TLABs should go to
415 // allocate_new_tlab().
416 //
417 // * All non-TLAB allocation requests should go to mem_allocate()
418 // and mem_allocate() should never be called with is_tlab == true.
419 //
420 // * If the GC locker is active we currently stall until we can
421 // allocate a new young region. This will be changed in the
422 // near future (see CR 6994056).
423 //
424 // * If either call cannot satisfy the allocation request using the
425 // current allocating region, they will try to get a new one. If
426 // this fails, they will attempt to do an evacuation pause and
427 // retry the allocation.
428 //
429 // * If all allocation attempts fail, even after trying to schedule
430 // an evacuation pause, allocate_new_tlab() will return NULL,
431 // whereas mem_allocate() will attempt a heap expansion and/or
432 // schedule a Full GC.
433 //
434 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
435 // should never be called with word_size being humongous. All
436 // humongous allocation requests should go to mem_allocate() which
437 // will satisfy them with a special path.
439 virtual HeapWord* allocate_new_tlab(size_t word_size);
441 virtual HeapWord* mem_allocate(size_t word_size,
442 bool is_noref,
443 bool is_tlab, /* expected to be false */
444 bool* gc_overhead_limit_was_exceeded);
446 // The following methods, allocate_from_cur_allocation_region(),
447 // attempt_allocation(), attempt_allocation_locked(),
448 // replace_cur_alloc_region_and_allocate(),
449 // attempt_allocation_slow(), and attempt_allocation_humongous()
450 // have very awkward pre- and post-conditions with respect to
451 // locking:
452 //
453 // If they are called outside a safepoint they assume the caller
454 // holds the Heap_lock when it calls them. However, on exit they
455 // will release the Heap_lock if they return a non-NULL result, but
456 // keep holding the Heap_lock if they return a NULL result. The
457 // reason for this is that we need to dirty the cards that span
458 // allocated blocks on young regions to avoid having to take the
459 // slow path of the write barrier (for performance reasons we don't
460 // update RSets for references whose source is a young region, so we
461 // don't need to look at dirty cards on young regions). But, doing
462 // this card dirtying while holding the Heap_lock can be a
463 // scalability bottleneck, especially given that some allocation
464 // requests might be of non-trivial size (and the larger the region
465 // size is, the fewer allocations requests will be considered
466 // humongous, as the humongous size limit is a fraction of the
467 // region size). So, when one of these calls succeeds in allocating
468 // a block it does the card dirtying after it releases the Heap_lock
469 // which is why it will return without holding it.
470 //
471 // The above assymetry is the reason why locking / unlocking is done
472 // explicitly (i.e., with Heap_lock->lock() and
473 // Heap_lock->unlocked()) instead of using MutexLocker and
474 // MutexUnlocker objects. The latter would ensure that the lock is
475 // unlocked / re-locked at every possible exit out of the basic
476 // block. However, we only want that action to happen in selected
477 // places.
478 //
479 // Further, if the above methods are called during a safepoint, then
480 // naturally there's no assumption about the Heap_lock being held or
481 // there's no attempt to unlock it. The parameter at_safepoint
482 // indicates whether the call is made during a safepoint or not (as
483 // an optimization, to avoid reading the global flag with
484 // SafepointSynchronize::is_at_safepoint()).
485 //
486 // The methods share these parameters:
487 //
488 // * word_size : the size of the allocation request in words
489 // * at_safepoint : whether the call is done at a safepoint; this
490 // also determines whether a GC is permitted
491 // (at_safepoint == false) or not (at_safepoint == true)
492 // * do_dirtying : whether the method should dirty the allocated
493 // block before returning
494 //
495 // They all return either the address of the block, if they
496 // successfully manage to allocate it, or NULL.
498 // It tries to satisfy an allocation request out of the current
499 // alloc region, which is passed as a parameter. It assumes that the
500 // caller has checked that the current alloc region is not NULL.
501 // Given that the caller has to check the current alloc region for
502 // at least NULL, it might as well pass it as the first parameter so
503 // that the method doesn't have to read it from the
504 // _cur_alloc_region field again. It is called from both
505 // attempt_allocation() and attempt_allocation_locked() and the
506 // with_heap_lock parameter indicates whether the caller was holding
507 // the heap lock when it called it or not.
508 inline HeapWord* allocate_from_cur_alloc_region(HeapRegion* cur_alloc_region,
509 size_t word_size,
510 bool with_heap_lock);
512 // First-level of allocation slow path: it attempts to allocate out
513 // of the current alloc region in a lock-free manner using a CAS. If
514 // that fails it takes the Heap_lock and calls
515 // attempt_allocation_locked() for the second-level slow path.
516 inline HeapWord* attempt_allocation(size_t word_size);
518 // Second-level of allocation slow path: while holding the Heap_lock
519 // it tries to allocate out of the current alloc region and, if that
520 // fails, tries to allocate out of a new current alloc region.
521 inline HeapWord* attempt_allocation_locked(size_t word_size);
523 // It assumes that the current alloc region has been retired and
524 // tries to allocate a new one. If it's successful, it performs the
525 // allocation out of the new current alloc region and updates
526 // _cur_alloc_region. Normally, it would try to allocate a new
527 // region if the young gen is not full, unless can_expand is true in
528 // which case it would always try to allocate a new region.
529 HeapWord* replace_cur_alloc_region_and_allocate(size_t word_size,
530 bool at_safepoint,
531 bool do_dirtying,
532 bool can_expand);
534 // Third-level of allocation slow path: when we are unable to
535 // allocate a new current alloc region to satisfy an allocation
536 // request (i.e., when attempt_allocation_locked() fails). It will
537 // try to do an evacuation pause, which might stall due to the GC
538 // locker, and retry the allocation attempt when appropriate.
539 HeapWord* attempt_allocation_slow(size_t word_size);
541 // The method that tries to satisfy a humongous allocation
542 // request. If it cannot satisfy it it will try to do an evacuation
543 // pause to perhaps reclaim enough space to be able to satisfy the
544 // allocation request afterwards.
545 HeapWord* attempt_allocation_humongous(size_t word_size,
546 bool at_safepoint);
548 // It does the common work when we are retiring the current alloc region.
549 inline void retire_cur_alloc_region_common(HeapRegion* cur_alloc_region);
551 // It retires the current alloc region, which is passed as a
552 // parameter (since, typically, the caller is already holding on to
553 // it). It sets _cur_alloc_region to NULL.
554 void retire_cur_alloc_region(HeapRegion* cur_alloc_region);
556 // It attempts to do an allocation immediately before or after an
557 // evacuation pause and can only be called by the VM thread. It has
558 // slightly different assumptions that the ones before (i.e.,
559 // assumes that the current alloc region has been retired).
560 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
561 bool expect_null_cur_alloc_region);
563 // It dirties the cards that cover the block so that so that the post
564 // write barrier never queues anything when updating objects on this
565 // block. It is assumed (and in fact we assert) that the block
566 // belongs to a young region.
567 inline void dirty_young_block(HeapWord* start, size_t word_size);
569 // Allocate blocks during garbage collection. Will ensure an
570 // allocation region, either by picking one or expanding the
571 // heap, and then allocate a block of the given size. The block
572 // may not be a humongous - it must fit into a single heap region.
573 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
575 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
576 HeapRegion* alloc_region,
577 bool par,
578 size_t word_size);
580 // Ensure that no further allocations can happen in "r", bearing in mind
581 // that parallel threads might be attempting allocations.
582 void par_allocate_remaining_space(HeapRegion* r);
584 // Retires an allocation region when it is full or at the end of a
585 // GC pause.
586 void retire_alloc_region(HeapRegion* alloc_region, bool par);
588 // - if explicit_gc is true, the GC is for a System.gc() or a heap
589 // inspection request and should collect the entire heap
590 // - if clear_all_soft_refs is true, all soft references should be
591 // cleared during the GC
592 // - if explicit_gc is false, word_size describes the allocation that
593 // the GC should attempt (at least) to satisfy
594 // - it returns false if it is unable to do the collection due to the
595 // GC locker being active, true otherwise
596 bool do_collection(bool explicit_gc,
597 bool clear_all_soft_refs,
598 size_t word_size);
600 // Callback from VM_G1CollectFull operation.
601 // Perform a full collection.
602 void do_full_collection(bool clear_all_soft_refs);
604 // Resize the heap if necessary after a full collection. If this is
605 // after a collect-for allocation, "word_size" is the allocation size,
606 // and will be considered part of the used portion of the heap.
607 void resize_if_necessary_after_full_collection(size_t word_size);
609 // Callback from VM_G1CollectForAllocation operation.
610 // This function does everything necessary/possible to satisfy a
611 // failed allocation request (including collection, expansion, etc.)
612 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
614 // Attempting to expand the heap sufficiently
615 // to support an allocation of the given "word_size". If
616 // successful, perform the allocation and return the address of the
617 // allocated block, or else "NULL".
618 HeapWord* expand_and_allocate(size_t word_size);
620 public:
621 // Expand the garbage-first heap by at least the given size (in bytes!).
622 // Returns true if the heap was expanded by the requested amount;
623 // false otherwise.
624 // (Rounds up to a HeapRegion boundary.)
625 bool expand(size_t expand_bytes);
627 // Do anything common to GC's.
628 virtual void gc_prologue(bool full);
629 virtual void gc_epilogue(bool full);
631 // We register a region with the fast "in collection set" test. We
632 // simply set to true the array slot corresponding to this region.
633 void register_region_with_in_cset_fast_test(HeapRegion* r) {
634 assert(_in_cset_fast_test_base != NULL, "sanity");
635 assert(r->in_collection_set(), "invariant");
636 int index = r->hrs_index();
637 assert(0 <= index && (size_t) index < _in_cset_fast_test_length, "invariant");
638 assert(!_in_cset_fast_test_base[index], "invariant");
639 _in_cset_fast_test_base[index] = true;
640 }
642 // This is a fast test on whether a reference points into the
643 // collection set or not. It does not assume that the reference
644 // points into the heap; if it doesn't, it will return false.
645 bool in_cset_fast_test(oop obj) {
646 assert(_in_cset_fast_test != NULL, "sanity");
647 if (_g1_committed.contains((HeapWord*) obj)) {
648 // no need to subtract the bottom of the heap from obj,
649 // _in_cset_fast_test is biased
650 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
651 bool ret = _in_cset_fast_test[index];
652 // let's make sure the result is consistent with what the slower
653 // test returns
654 assert( ret || !obj_in_cs(obj), "sanity");
655 assert(!ret || obj_in_cs(obj), "sanity");
656 return ret;
657 } else {
658 return false;
659 }
660 }
662 void clear_cset_fast_test() {
663 assert(_in_cset_fast_test_base != NULL, "sanity");
664 memset(_in_cset_fast_test_base, false,
665 _in_cset_fast_test_length * sizeof(bool));
666 }
668 // This is called at the end of either a concurrent cycle or a Full
669 // GC to update the number of full collections completed. Those two
670 // can happen in a nested fashion, i.e., we start a concurrent
671 // cycle, a Full GC happens half-way through it which ends first,
672 // and then the cycle notices that a Full GC happened and ends
673 // too. The concurrent parameter is a boolean to help us do a bit
674 // tighter consistency checking in the method. If concurrent is
675 // false, the caller is the inner caller in the nesting (i.e., the
676 // Full GC). If concurrent is true, the caller is the outer caller
677 // in this nesting (i.e., the concurrent cycle). Further nesting is
678 // not currently supported. The end of the this call also notifies
679 // the FullGCCount_lock in case a Java thread is waiting for a full
680 // GC to happen (e.g., it called System.gc() with
681 // +ExplicitGCInvokesConcurrent).
682 void increment_full_collections_completed(bool concurrent);
684 unsigned int full_collections_completed() {
685 return _full_collections_completed;
686 }
688 protected:
690 // Shrink the garbage-first heap by at most the given size (in bytes!).
691 // (Rounds down to a HeapRegion boundary.)
692 virtual void shrink(size_t expand_bytes);
693 void shrink_helper(size_t expand_bytes);
695 #if TASKQUEUE_STATS
696 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
697 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
698 void reset_taskqueue_stats();
699 #endif // TASKQUEUE_STATS
701 // Schedule the VM operation that will do an evacuation pause to
702 // satisfy an allocation request of word_size. *succeeded will
703 // return whether the VM operation was successful (it did do an
704 // evacuation pause) or not (another thread beat us to it or the GC
705 // locker was active). Given that we should not be holding the
706 // Heap_lock when we enter this method, we will pass the
707 // gc_count_before (i.e., total_collections()) as a parameter since
708 // it has to be read while holding the Heap_lock. Currently, both
709 // methods that call do_collection_pause() release the Heap_lock
710 // before the call, so it's easy to read gc_count_before just before.
711 HeapWord* do_collection_pause(size_t word_size,
712 unsigned int gc_count_before,
713 bool* succeeded);
715 // The guts of the incremental collection pause, executed by the vm
716 // thread. It returns false if it is unable to do the collection due
717 // to the GC locker being active, true otherwise
718 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
720 // Actually do the work of evacuating the collection set.
721 void evacuate_collection_set();
723 // The g1 remembered set of the heap.
724 G1RemSet* _g1_rem_set;
725 // And it's mod ref barrier set, used to track updates for the above.
726 ModRefBarrierSet* _mr_bs;
728 // A set of cards that cover the objects for which the Rsets should be updated
729 // concurrently after the collection.
730 DirtyCardQueueSet _dirty_card_queue_set;
732 // The Heap Region Rem Set Iterator.
733 HeapRegionRemSetIterator** _rem_set_iterator;
735 // The closure used to refine a single card.
736 RefineCardTableEntryClosure* _refine_cte_cl;
738 // A function to check the consistency of dirty card logs.
739 void check_ct_logs_at_safepoint();
741 // A DirtyCardQueueSet that is used to hold cards that contain
742 // references into the current collection set. This is used to
743 // update the remembered sets of the regions in the collection
744 // set in the event of an evacuation failure.
745 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
747 // After a collection pause, make the regions in the CS into free
748 // regions.
749 void free_collection_set(HeapRegion* cs_head);
751 // Abandon the current collection set without recording policy
752 // statistics or updating free lists.
753 void abandon_collection_set(HeapRegion* cs_head);
755 // Applies "scan_non_heap_roots" to roots outside the heap,
756 // "scan_rs" to roots inside the heap (having done "set_region" to
757 // indicate the region in which the root resides), and does "scan_perm"
758 // (setting the generation to the perm generation.) If "scan_rs" is
759 // NULL, then this step is skipped. The "worker_i"
760 // param is for use with parallel roots processing, and should be
761 // the "i" of the calling parallel worker thread's work(i) function.
762 // In the sequential case this param will be ignored.
763 void g1_process_strong_roots(bool collecting_perm_gen,
764 SharedHeap::ScanningOption so,
765 OopClosure* scan_non_heap_roots,
766 OopsInHeapRegionClosure* scan_rs,
767 OopsInGenClosure* scan_perm,
768 int worker_i);
770 // Apply "blk" to all the weak roots of the system. These include
771 // JNI weak roots, the code cache, system dictionary, symbol table,
772 // string table, and referents of reachable weak refs.
773 void g1_process_weak_roots(OopClosure* root_closure,
774 OopClosure* non_root_closure);
776 // Invoke "save_marks" on all heap regions.
777 void save_marks();
779 // It frees a non-humongous region by initializing its contents and
780 // adding it to the free list that's passed as a parameter (this is
781 // usually a local list which will be appended to the master free
782 // list later). The used bytes of freed regions are accumulated in
783 // pre_used. If par is true, the region's RSet will not be freed
784 // up. The assumption is that this will be done later.
785 void free_region(HeapRegion* hr,
786 size_t* pre_used,
787 FreeRegionList* free_list,
788 bool par);
790 // It frees a humongous region by collapsing it into individual
791 // regions and calling free_region() for each of them. The freed
792 // regions will be added to the free list that's passed as a parameter
793 // (this is usually a local list which will be appended to the
794 // master free list later). The used bytes of freed regions are
795 // accumulated in pre_used. If par is true, the region's RSet will
796 // not be freed up. The assumption is that this will be done later.
797 void free_humongous_region(HeapRegion* hr,
798 size_t* pre_used,
799 FreeRegionList* free_list,
800 HumongousRegionSet* humongous_proxy_set,
801 bool par);
803 // The concurrent marker (and the thread it runs in.)
804 ConcurrentMark* _cm;
805 ConcurrentMarkThread* _cmThread;
806 bool _mark_in_progress;
808 // The concurrent refiner.
809 ConcurrentG1Refine* _cg1r;
811 // The parallel task queues
812 RefToScanQueueSet *_task_queues;
814 // True iff a evacuation has failed in the current collection.
815 bool _evacuation_failed;
817 // Set the attribute indicating whether evacuation has failed in the
818 // current collection.
819 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
821 // Failed evacuations cause some logical from-space objects to have
822 // forwarding pointers to themselves. Reset them.
823 void remove_self_forwarding_pointers();
825 // When one is non-null, so is the other. Together, they each pair is
826 // an object with a preserved mark, and its mark value.
827 GrowableArray<oop>* _objs_with_preserved_marks;
828 GrowableArray<markOop>* _preserved_marks_of_objs;
830 // Preserve the mark of "obj", if necessary, in preparation for its mark
831 // word being overwritten with a self-forwarding-pointer.
832 void preserve_mark_if_necessary(oop obj, markOop m);
834 // The stack of evac-failure objects left to be scanned.
835 GrowableArray<oop>* _evac_failure_scan_stack;
836 // The closure to apply to evac-failure objects.
838 OopsInHeapRegionClosure* _evac_failure_closure;
839 // Set the field above.
840 void
841 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
842 _evac_failure_closure = evac_failure_closure;
843 }
845 // Push "obj" on the scan stack.
846 void push_on_evac_failure_scan_stack(oop obj);
847 // Process scan stack entries until the stack is empty.
848 void drain_evac_failure_scan_stack();
849 // True iff an invocation of "drain_scan_stack" is in progress; to
850 // prevent unnecessary recursion.
851 bool _drain_in_progress;
853 // Do any necessary initialization for evacuation-failure handling.
854 // "cl" is the closure that will be used to process evac-failure
855 // objects.
856 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
857 // Do any necessary cleanup for evacuation-failure handling data
858 // structures.
859 void finalize_for_evac_failure();
861 // An attempt to evacuate "obj" has failed; take necessary steps.
862 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
863 void handle_evacuation_failure_common(oop obj, markOop m);
866 // Ensure that the relevant gc_alloc regions are set.
867 void get_gc_alloc_regions();
868 // We're done with GC alloc regions. We are going to tear down the
869 // gc alloc list and remove the gc alloc tag from all the regions on
870 // that list. However, we will also retain the last (i.e., the one
871 // that is half-full) GC alloc region, per GCAllocPurpose, for
872 // possible reuse during the next collection, provided
873 // _retain_gc_alloc_region[] indicates that it should be the
874 // case. Said regions are kept in the _retained_gc_alloc_regions[]
875 // array. If the parameter totally is set, we will not retain any
876 // regions, irrespective of what _retain_gc_alloc_region[]
877 // indicates.
878 void release_gc_alloc_regions(bool totally);
879 #ifndef PRODUCT
880 // Useful for debugging.
881 void print_gc_alloc_regions();
882 #endif // !PRODUCT
884 // Instance of the concurrent mark is_alive closure for embedding
885 // into the reference processor as the is_alive_non_header. This
886 // prevents unnecessary additions to the discovered lists during
887 // concurrent discovery.
888 G1CMIsAliveClosure _is_alive_closure;
890 // ("Weak") Reference processing support
891 ReferenceProcessor* _ref_processor;
893 enum G1H_process_strong_roots_tasks {
894 G1H_PS_mark_stack_oops_do,
895 G1H_PS_refProcessor_oops_do,
896 // Leave this one last.
897 G1H_PS_NumElements
898 };
900 SubTasksDone* _process_strong_tasks;
902 volatile bool _free_regions_coming;
904 public:
906 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
908 void set_refine_cte_cl_concurrency(bool concurrent);
910 RefToScanQueue *task_queue(int i) const;
912 // A set of cards where updates happened during the GC
913 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
915 // A DirtyCardQueueSet that is used to hold cards that contain
916 // references into the current collection set. This is used to
917 // update the remembered sets of the regions in the collection
918 // set in the event of an evacuation failure.
919 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
920 { return _into_cset_dirty_card_queue_set; }
922 // Create a G1CollectedHeap with the specified policy.
923 // Must call the initialize method afterwards.
924 // May not return if something goes wrong.
925 G1CollectedHeap(G1CollectorPolicy* policy);
927 // Initialize the G1CollectedHeap to have the initial and
928 // maximum sizes, permanent generation, and remembered and barrier sets
929 // specified by the policy object.
930 jint initialize();
932 virtual void ref_processing_init();
934 void set_par_threads(int t) {
935 SharedHeap::set_par_threads(t);
936 _process_strong_tasks->set_n_threads(t);
937 }
939 virtual CollectedHeap::Name kind() const {
940 return CollectedHeap::G1CollectedHeap;
941 }
943 // The current policy object for the collector.
944 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
946 // Adaptive size policy. No such thing for g1.
947 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
949 // The rem set and barrier set.
950 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
951 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
953 // The rem set iterator.
954 HeapRegionRemSetIterator* rem_set_iterator(int i) {
955 return _rem_set_iterator[i];
956 }
958 HeapRegionRemSetIterator* rem_set_iterator() {
959 return _rem_set_iterator[0];
960 }
962 unsigned get_gc_time_stamp() {
963 return _gc_time_stamp;
964 }
966 void reset_gc_time_stamp() {
967 _gc_time_stamp = 0;
968 OrderAccess::fence();
969 }
971 void increment_gc_time_stamp() {
972 ++_gc_time_stamp;
973 OrderAccess::fence();
974 }
976 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
977 DirtyCardQueue* into_cset_dcq,
978 bool concurrent, int worker_i);
980 // The shared block offset table array.
981 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
983 // Reference Processing accessor
984 ReferenceProcessor* ref_processor() { return _ref_processor; }
986 virtual size_t capacity() const;
987 virtual size_t used() const;
988 // This should be called when we're not holding the heap lock. The
989 // result might be a bit inaccurate.
990 size_t used_unlocked() const;
991 size_t recalculate_used() const;
992 #ifndef PRODUCT
993 size_t recalculate_used_regions() const;
994 #endif // PRODUCT
996 // These virtual functions do the actual allocation.
997 // Some heaps may offer a contiguous region for shared non-blocking
998 // allocation, via inlined code (by exporting the address of the top and
999 // end fields defining the extent of the contiguous allocation region.)
1000 // But G1CollectedHeap doesn't yet support this.
1002 // Return an estimate of the maximum allocation that could be performed
1003 // without triggering any collection or expansion activity. In a
1004 // generational collector, for example, this is probably the largest
1005 // allocation that could be supported (without expansion) in the youngest
1006 // generation. It is "unsafe" because no locks are taken; the result
1007 // should be treated as an approximation, not a guarantee, for use in
1008 // heuristic resizing decisions.
1009 virtual size_t unsafe_max_alloc();
1011 virtual bool is_maximal_no_gc() const {
1012 return _g1_storage.uncommitted_size() == 0;
1013 }
1015 // The total number of regions in the heap.
1016 size_t n_regions();
1018 // The number of regions that are completely free.
1019 size_t max_regions();
1021 // The number of regions that are completely free.
1022 size_t free_regions() {
1023 return _free_list.length();
1024 }
1026 // The number of regions that are not completely free.
1027 size_t used_regions() { return n_regions() - free_regions(); }
1029 // The number of regions available for "regular" expansion.
1030 size_t expansion_regions() { return _expansion_regions; }
1032 // verify_region_sets() performs verification over the region
1033 // lists. It will be compiled in the product code to be used when
1034 // necessary (i.e., during heap verification).
1035 void verify_region_sets();
1037 // verify_region_sets_optional() is planted in the code for
1038 // list verification in non-product builds (and it can be enabled in
1039 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1040 #if HEAP_REGION_SET_FORCE_VERIFY
1041 void verify_region_sets_optional() {
1042 verify_region_sets();
1043 }
1044 #else // HEAP_REGION_SET_FORCE_VERIFY
1045 void verify_region_sets_optional() { }
1046 #endif // HEAP_REGION_SET_FORCE_VERIFY
1048 #ifdef ASSERT
1049 bool is_on_free_list(HeapRegion* hr) {
1050 return hr->containing_set() == &_free_list;
1051 }
1053 bool is_on_humongous_set(HeapRegion* hr) {
1054 return hr->containing_set() == &_humongous_set;
1055 }
1056 #endif // ASSERT
1058 // Wrapper for the region list operations that can be called from
1059 // methods outside this class.
1061 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1062 _secondary_free_list.add_as_tail(list);
1063 }
1065 void append_secondary_free_list() {
1066 _free_list.add_as_tail(&_secondary_free_list);
1067 }
1069 void append_secondary_free_list_if_not_empty() {
1070 if (!_secondary_free_list.is_empty()) {
1071 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1072 append_secondary_free_list();
1073 }
1074 }
1076 void set_free_regions_coming();
1077 void reset_free_regions_coming();
1078 bool free_regions_coming() { return _free_regions_coming; }
1079 void wait_while_free_regions_coming();
1081 // Perform a collection of the heap; intended for use in implementing
1082 // "System.gc". This probably implies as full a collection as the
1083 // "CollectedHeap" supports.
1084 virtual void collect(GCCause::Cause cause);
1086 // The same as above but assume that the caller holds the Heap_lock.
1087 void collect_locked(GCCause::Cause cause);
1089 // This interface assumes that it's being called by the
1090 // vm thread. It collects the heap assuming that the
1091 // heap lock is already held and that we are executing in
1092 // the context of the vm thread.
1093 virtual void collect_as_vm_thread(GCCause::Cause cause);
1095 // True iff a evacuation has failed in the most-recent collection.
1096 bool evacuation_failed() { return _evacuation_failed; }
1098 // It will free a region if it has allocated objects in it that are
1099 // all dead. It calls either free_region() or
1100 // free_humongous_region() depending on the type of the region that
1101 // is passed to it.
1102 void free_region_if_empty(HeapRegion* hr,
1103 size_t* pre_used,
1104 FreeRegionList* free_list,
1105 HumongousRegionSet* humongous_proxy_set,
1106 HRRSCleanupTask* hrrs_cleanup_task,
1107 bool par);
1109 // It appends the free list to the master free list and updates the
1110 // master humongous list according to the contents of the proxy
1111 // list. It also adjusts the total used bytes according to pre_used
1112 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1113 void update_sets_after_freeing_regions(size_t pre_used,
1114 FreeRegionList* free_list,
1115 HumongousRegionSet* humongous_proxy_set,
1116 bool par);
1118 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1119 virtual bool is_in(const void* p) const;
1121 // Return "TRUE" iff the given object address is within the collection
1122 // set.
1123 inline bool obj_in_cs(oop obj);
1125 // Return "TRUE" iff the given object address is in the reserved
1126 // region of g1 (excluding the permanent generation).
1127 bool is_in_g1_reserved(const void* p) const {
1128 return _g1_reserved.contains(p);
1129 }
1131 // Returns a MemRegion that corresponds to the space that has been
1132 // committed in the heap
1133 MemRegion g1_committed() {
1134 return _g1_committed;
1135 }
1137 NOT_PRODUCT(bool is_in_closed_subset(const void* p) const;)
1139 // Dirty card table entries covering a list of young regions.
1140 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1142 // This resets the card table to all zeros. It is used after
1143 // a collection pause which used the card table to claim cards.
1144 void cleanUpCardTable();
1146 // Iteration functions.
1148 // Iterate over all the ref-containing fields of all objects, calling
1149 // "cl.do_oop" on each.
1150 virtual void oop_iterate(OopClosure* cl) {
1151 oop_iterate(cl, true);
1152 }
1153 void oop_iterate(OopClosure* cl, bool do_perm);
1155 // Same as above, restricted to a memory region.
1156 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1157 oop_iterate(mr, cl, true);
1158 }
1159 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1161 // Iterate over all objects, calling "cl.do_object" on each.
1162 virtual void object_iterate(ObjectClosure* cl) {
1163 object_iterate(cl, true);
1164 }
1165 virtual void safe_object_iterate(ObjectClosure* cl) {
1166 object_iterate(cl, true);
1167 }
1168 void object_iterate(ObjectClosure* cl, bool do_perm);
1170 // Iterate over all objects allocated since the last collection, calling
1171 // "cl.do_object" on each. The heap must have been initialized properly
1172 // to support this function, or else this call will fail.
1173 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1175 // Iterate over all spaces in use in the heap, in ascending address order.
1176 virtual void space_iterate(SpaceClosure* cl);
1178 // Iterate over heap regions, in address order, terminating the
1179 // iteration early if the "doHeapRegion" method returns "true".
1180 void heap_region_iterate(HeapRegionClosure* blk);
1182 // Iterate over heap regions starting with r (or the first region if "r"
1183 // is NULL), in address order, terminating early if the "doHeapRegion"
1184 // method returns "true".
1185 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk);
1187 // As above but starting from the region at index idx.
1188 void heap_region_iterate_from(int idx, HeapRegionClosure* blk);
1190 HeapRegion* region_at(size_t idx);
1192 // Divide the heap region sequence into "chunks" of some size (the number
1193 // of regions divided by the number of parallel threads times some
1194 // overpartition factor, currently 4). Assumes that this will be called
1195 // in parallel by ParallelGCThreads worker threads with discinct worker
1196 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1197 // calls will use the same "claim_value", and that that claim value is
1198 // different from the claim_value of any heap region before the start of
1199 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1200 // attempting to claim the first region in each chunk, and, if
1201 // successful, applying the closure to each region in the chunk (and
1202 // setting the claim value of the second and subsequent regions of the
1203 // chunk.) For now requires that "doHeapRegion" always returns "false",
1204 // i.e., that a closure never attempt to abort a traversal.
1205 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1206 int worker,
1207 jint claim_value);
1209 // It resets all the region claim values to the default.
1210 void reset_heap_region_claim_values();
1212 #ifdef ASSERT
1213 bool check_heap_region_claim_values(jint claim_value);
1214 #endif // ASSERT
1216 // Iterate over the regions (if any) in the current collection set.
1217 void collection_set_iterate(HeapRegionClosure* blk);
1219 // As above but starting from region r
1220 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1222 // Returns the first (lowest address) compactible space in the heap.
1223 virtual CompactibleSpace* first_compactible_space();
1225 // A CollectedHeap will contain some number of spaces. This finds the
1226 // space containing a given address, or else returns NULL.
1227 virtual Space* space_containing(const void* addr) const;
1229 // A G1CollectedHeap will contain some number of heap regions. This
1230 // finds the region containing a given address, or else returns NULL.
1231 HeapRegion* heap_region_containing(const void* addr) const;
1233 // Like the above, but requires "addr" to be in the heap (to avoid a
1234 // null-check), and unlike the above, may return an continuing humongous
1235 // region.
1236 HeapRegion* heap_region_containing_raw(const void* addr) const;
1238 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1239 // each address in the (reserved) heap is a member of exactly
1240 // one block. The defining characteristic of a block is that it is
1241 // possible to find its size, and thus to progress forward to the next
1242 // block. (Blocks may be of different sizes.) Thus, blocks may
1243 // represent Java objects, or they might be free blocks in a
1244 // free-list-based heap (or subheap), as long as the two kinds are
1245 // distinguishable and the size of each is determinable.
1247 // Returns the address of the start of the "block" that contains the
1248 // address "addr". We say "blocks" instead of "object" since some heaps
1249 // may not pack objects densely; a chunk may either be an object or a
1250 // non-object.
1251 virtual HeapWord* block_start(const void* addr) const;
1253 // Requires "addr" to be the start of a chunk, and returns its size.
1254 // "addr + size" is required to be the start of a new chunk, or the end
1255 // of the active area of the heap.
1256 virtual size_t block_size(const HeapWord* addr) const;
1258 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1259 // the block is an object.
1260 virtual bool block_is_obj(const HeapWord* addr) const;
1262 // Does this heap support heap inspection? (+PrintClassHistogram)
1263 virtual bool supports_heap_inspection() const { return true; }
1265 // Section on thread-local allocation buffers (TLABs)
1266 // See CollectedHeap for semantics.
1268 virtual bool supports_tlab_allocation() const;
1269 virtual size_t tlab_capacity(Thread* thr) const;
1270 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1272 // Can a compiler initialize a new object without store barriers?
1273 // This permission only extends from the creation of a new object
1274 // via a TLAB up to the first subsequent safepoint. If such permission
1275 // is granted for this heap type, the compiler promises to call
1276 // defer_store_barrier() below on any slow path allocation of
1277 // a new object for which such initializing store barriers will
1278 // have been elided. G1, like CMS, allows this, but should be
1279 // ready to provide a compensating write barrier as necessary
1280 // if that storage came out of a non-young region. The efficiency
1281 // of this implementation depends crucially on being able to
1282 // answer very efficiently in constant time whether a piece of
1283 // storage in the heap comes from a young region or not.
1284 // See ReduceInitialCardMarks.
1285 virtual bool can_elide_tlab_store_barriers() const {
1286 // 6920090: Temporarily disabled, because of lingering
1287 // instabilities related to RICM with G1. In the
1288 // interim, the option ReduceInitialCardMarksForG1
1289 // below is left solely as a debugging device at least
1290 // until 6920109 fixes the instabilities.
1291 return ReduceInitialCardMarksForG1;
1292 }
1294 virtual bool card_mark_must_follow_store() const {
1295 return true;
1296 }
1298 bool is_in_young(oop obj) {
1299 HeapRegion* hr = heap_region_containing(obj);
1300 return hr != NULL && hr->is_young();
1301 }
1303 // We don't need barriers for initializing stores to objects
1304 // in the young gen: for the SATB pre-barrier, there is no
1305 // pre-value that needs to be remembered; for the remembered-set
1306 // update logging post-barrier, we don't maintain remembered set
1307 // information for young gen objects. Note that non-generational
1308 // G1 does not have any "young" objects, should not elide
1309 // the rs logging barrier and so should always answer false below.
1310 // However, non-generational G1 (-XX:-G1Gen) appears to have
1311 // bit-rotted so was not tested below.
1312 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1313 // Re 6920090, 6920109 above.
1314 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1315 assert(G1Gen || !is_in_young(new_obj),
1316 "Non-generational G1 should never return true below");
1317 return is_in_young(new_obj);
1318 }
1320 // Can a compiler elide a store barrier when it writes
1321 // a permanent oop into the heap? Applies when the compiler
1322 // is storing x to the heap, where x->is_perm() is true.
1323 virtual bool can_elide_permanent_oop_store_barriers() const {
1324 // At least until perm gen collection is also G1-ified, at
1325 // which point this should return false.
1326 return true;
1327 }
1329 // The boundary between a "large" and "small" array of primitives, in
1330 // words.
1331 virtual size_t large_typearray_limit();
1333 // Returns "true" iff the given word_size is "very large".
1334 static bool isHumongous(size_t word_size) {
1335 // Note this has to be strictly greater-than as the TLABs
1336 // are capped at the humongous thresold and we want to
1337 // ensure that we don't try to allocate a TLAB as
1338 // humongous and that we don't allocate a humongous
1339 // object in a TLAB.
1340 return word_size > _humongous_object_threshold_in_words;
1341 }
1343 // Update mod union table with the set of dirty cards.
1344 void updateModUnion();
1346 // Set the mod union bits corresponding to the given memRegion. Note
1347 // that this is always a safe operation, since it doesn't clear any
1348 // bits.
1349 void markModUnionRange(MemRegion mr);
1351 // Records the fact that a marking phase is no longer in progress.
1352 void set_marking_complete() {
1353 _mark_in_progress = false;
1354 }
1355 void set_marking_started() {
1356 _mark_in_progress = true;
1357 }
1358 bool mark_in_progress() {
1359 return _mark_in_progress;
1360 }
1362 // Print the maximum heap capacity.
1363 virtual size_t max_capacity() const;
1365 virtual jlong millis_since_last_gc();
1367 // Perform any cleanup actions necessary before allowing a verification.
1368 virtual void prepare_for_verify();
1370 // Perform verification.
1372 // use_prev_marking == true -> use "prev" marking information,
1373 // use_prev_marking == false -> use "next" marking information
1374 // NOTE: Only the "prev" marking information is guaranteed to be
1375 // consistent most of the time, so most calls to this should use
1376 // use_prev_marking == true. Currently, there is only one case where
1377 // this is called with use_prev_marking == false, which is to verify
1378 // the "next" marking information at the end of remark.
1379 void verify(bool allow_dirty, bool silent, bool use_prev_marking);
1381 // Override; it uses the "prev" marking information
1382 virtual void verify(bool allow_dirty, bool silent);
1383 // Default behavior by calling print(tty);
1384 virtual void print() const;
1385 // This calls print_on(st, PrintHeapAtGCExtended).
1386 virtual void print_on(outputStream* st) const;
1387 // If extended is true, it will print out information for all
1388 // regions in the heap by calling print_on_extended(st).
1389 virtual void print_on(outputStream* st, bool extended) const;
1390 virtual void print_on_extended(outputStream* st) const;
1392 virtual void print_gc_threads_on(outputStream* st) const;
1393 virtual void gc_threads_do(ThreadClosure* tc) const;
1395 // Override
1396 void print_tracing_info() const;
1398 // If "addr" is a pointer into the (reserved?) heap, returns a positive
1399 // number indicating the "arena" within the heap in which "addr" falls.
1400 // Or else returns 0.
1401 virtual int addr_to_arena_id(void* addr) const;
1403 // Convenience function to be used in situations where the heap type can be
1404 // asserted to be this type.
1405 static G1CollectedHeap* heap();
1407 void empty_young_list();
1409 void set_region_short_lived_locked(HeapRegion* hr);
1410 // add appropriate methods for any other surv rate groups
1412 YoungList* young_list() { return _young_list; }
1414 // debugging
1415 bool check_young_list_well_formed() {
1416 return _young_list->check_list_well_formed();
1417 }
1419 bool check_young_list_empty(bool check_heap,
1420 bool check_sample = true);
1422 // *** Stuff related to concurrent marking. It's not clear to me that so
1423 // many of these need to be public.
1425 // The functions below are helper functions that a subclass of
1426 // "CollectedHeap" can use in the implementation of its virtual
1427 // functions.
1428 // This performs a concurrent marking of the live objects in a
1429 // bitmap off to the side.
1430 void doConcurrentMark();
1432 // This is called from the marksweep collector which then does
1433 // a concurrent mark and verifies that the results agree with
1434 // the stop the world marking.
1435 void checkConcurrentMark();
1436 void do_sync_mark();
1438 bool isMarkedPrev(oop obj) const;
1439 bool isMarkedNext(oop obj) const;
1441 // use_prev_marking == true -> use "prev" marking information,
1442 // use_prev_marking == false -> use "next" marking information
1443 bool is_obj_dead_cond(const oop obj,
1444 const HeapRegion* hr,
1445 const bool use_prev_marking) const {
1446 if (use_prev_marking) {
1447 return is_obj_dead(obj, hr);
1448 } else {
1449 return is_obj_ill(obj, hr);
1450 }
1451 }
1453 // Determine if an object is dead, given the object and also
1454 // the region to which the object belongs. An object is dead
1455 // iff a) it was not allocated since the last mark and b) it
1456 // is not marked.
1458 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1459 return
1460 !hr->obj_allocated_since_prev_marking(obj) &&
1461 !isMarkedPrev(obj);
1462 }
1464 // This is used when copying an object to survivor space.
1465 // If the object is marked live, then we mark the copy live.
1466 // If the object is allocated since the start of this mark
1467 // cycle, then we mark the copy live.
1468 // If the object has been around since the previous mark
1469 // phase, and hasn't been marked yet during this phase,
1470 // then we don't mark it, we just wait for the
1471 // current marking cycle to get to it.
1473 // This function returns true when an object has been
1474 // around since the previous marking and hasn't yet
1475 // been marked during this marking.
1477 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1478 return
1479 !hr->obj_allocated_since_next_marking(obj) &&
1480 !isMarkedNext(obj);
1481 }
1483 // Determine if an object is dead, given only the object itself.
1484 // This will find the region to which the object belongs and
1485 // then call the region version of the same function.
1487 // Added if it is in permanent gen it isn't dead.
1488 // Added if it is NULL it isn't dead.
1490 // use_prev_marking == true -> use "prev" marking information,
1491 // use_prev_marking == false -> use "next" marking information
1492 bool is_obj_dead_cond(const oop obj,
1493 const bool use_prev_marking) {
1494 if (use_prev_marking) {
1495 return is_obj_dead(obj);
1496 } else {
1497 return is_obj_ill(obj);
1498 }
1499 }
1501 bool is_obj_dead(const oop obj) {
1502 const HeapRegion* hr = heap_region_containing(obj);
1503 if (hr == NULL) {
1504 if (Universe::heap()->is_in_permanent(obj))
1505 return false;
1506 else if (obj == NULL) return false;
1507 else return true;
1508 }
1509 else return is_obj_dead(obj, hr);
1510 }
1512 bool is_obj_ill(const oop obj) {
1513 const HeapRegion* hr = heap_region_containing(obj);
1514 if (hr == NULL) {
1515 if (Universe::heap()->is_in_permanent(obj))
1516 return false;
1517 else if (obj == NULL) return false;
1518 else return true;
1519 }
1520 else return is_obj_ill(obj, hr);
1521 }
1523 // The following is just to alert the verification code
1524 // that a full collection has occurred and that the
1525 // remembered sets are no longer up to date.
1526 bool _full_collection;
1527 void set_full_collection() { _full_collection = true;}
1528 void clear_full_collection() {_full_collection = false;}
1529 bool full_collection() {return _full_collection;}
1531 ConcurrentMark* concurrent_mark() const { return _cm; }
1532 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1534 // The dirty cards region list is used to record a subset of regions
1535 // whose cards need clearing. The list if populated during the
1536 // remembered set scanning and drained during the card table
1537 // cleanup. Although the methods are reentrant, population/draining
1538 // phases must not overlap. For synchronization purposes the last
1539 // element on the list points to itself.
1540 HeapRegion* _dirty_cards_region_list;
1541 void push_dirty_cards_region(HeapRegion* hr);
1542 HeapRegion* pop_dirty_cards_region();
1544 public:
1545 void stop_conc_gc_threads();
1547 // <NEW PREDICTION>
1549 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1550 void check_if_region_is_too_expensive(double predicted_time_ms);
1551 size_t pending_card_num();
1552 size_t max_pending_card_num();
1553 size_t cards_scanned();
1555 // </NEW PREDICTION>
1557 protected:
1558 size_t _max_heap_capacity;
1559 };
1561 #define use_local_bitmaps 1
1562 #define verify_local_bitmaps 0
1563 #define oop_buffer_length 256
1565 #ifndef PRODUCT
1566 class GCLabBitMap;
1567 class GCLabBitMapClosure: public BitMapClosure {
1568 private:
1569 ConcurrentMark* _cm;
1570 GCLabBitMap* _bitmap;
1572 public:
1573 GCLabBitMapClosure(ConcurrentMark* cm,
1574 GCLabBitMap* bitmap) {
1575 _cm = cm;
1576 _bitmap = bitmap;
1577 }
1579 virtual bool do_bit(size_t offset);
1580 };
1581 #endif // !PRODUCT
1583 class GCLabBitMap: public BitMap {
1584 private:
1585 ConcurrentMark* _cm;
1587 int _shifter;
1588 size_t _bitmap_word_covers_words;
1590 // beginning of the heap
1591 HeapWord* _heap_start;
1593 // this is the actual start of the GCLab
1594 HeapWord* _real_start_word;
1596 // this is the actual end of the GCLab
1597 HeapWord* _real_end_word;
1599 // this is the first word, possibly located before the actual start
1600 // of the GCLab, that corresponds to the first bit of the bitmap
1601 HeapWord* _start_word;
1603 // size of a GCLab in words
1604 size_t _gclab_word_size;
1606 static int shifter() {
1607 return MinObjAlignment - 1;
1608 }
1610 // how many heap words does a single bitmap word corresponds to?
1611 static size_t bitmap_word_covers_words() {
1612 return BitsPerWord << shifter();
1613 }
1615 size_t gclab_word_size() const {
1616 return _gclab_word_size;
1617 }
1619 // Calculates actual GCLab size in words
1620 size_t gclab_real_word_size() const {
1621 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1622 / BitsPerWord;
1623 }
1625 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1626 size_t bits_in_bitmap = gclab_word_size >> shifter();
1627 // We are going to ensure that the beginning of a word in this
1628 // bitmap also corresponds to the beginning of a word in the
1629 // global marking bitmap. To handle the case where a GCLab
1630 // starts from the middle of the bitmap, we need to add enough
1631 // space (i.e. up to a bitmap word) to ensure that we have
1632 // enough bits in the bitmap.
1633 return bits_in_bitmap + BitsPerWord - 1;
1634 }
1635 public:
1636 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1637 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1638 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1639 _shifter(shifter()),
1640 _bitmap_word_covers_words(bitmap_word_covers_words()),
1641 _heap_start(heap_start),
1642 _gclab_word_size(gclab_word_size),
1643 _real_start_word(NULL),
1644 _real_end_word(NULL),
1645 _start_word(NULL)
1646 {
1647 guarantee( size_in_words() >= bitmap_size_in_words(),
1648 "just making sure");
1649 }
1651 inline unsigned heapWordToOffset(HeapWord* addr) {
1652 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1653 assert(offset < size(), "offset should be within bounds");
1654 return offset;
1655 }
1657 inline HeapWord* offsetToHeapWord(size_t offset) {
1658 HeapWord* addr = _start_word + (offset << _shifter);
1659 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1660 return addr;
1661 }
1663 bool fields_well_formed() {
1664 bool ret1 = (_real_start_word == NULL) &&
1665 (_real_end_word == NULL) &&
1666 (_start_word == NULL);
1667 if (ret1)
1668 return true;
1670 bool ret2 = _real_start_word >= _start_word &&
1671 _start_word < _real_end_word &&
1672 (_real_start_word + _gclab_word_size) == _real_end_word &&
1673 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1674 > _real_end_word;
1675 return ret2;
1676 }
1678 inline bool mark(HeapWord* addr) {
1679 guarantee(use_local_bitmaps, "invariant");
1680 assert(fields_well_formed(), "invariant");
1682 if (addr >= _real_start_word && addr < _real_end_word) {
1683 assert(!isMarked(addr), "should not have already been marked");
1685 // first mark it on the bitmap
1686 at_put(heapWordToOffset(addr), true);
1688 return true;
1689 } else {
1690 return false;
1691 }
1692 }
1694 inline bool isMarked(HeapWord* addr) {
1695 guarantee(use_local_bitmaps, "invariant");
1696 assert(fields_well_formed(), "invariant");
1698 return at(heapWordToOffset(addr));
1699 }
1701 void set_buffer(HeapWord* start) {
1702 guarantee(use_local_bitmaps, "invariant");
1703 clear();
1705 assert(start != NULL, "invariant");
1706 _real_start_word = start;
1707 _real_end_word = start + _gclab_word_size;
1709 size_t diff =
1710 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1711 _start_word = start - diff;
1713 assert(fields_well_formed(), "invariant");
1714 }
1716 #ifndef PRODUCT
1717 void verify() {
1718 // verify that the marks have been propagated
1719 GCLabBitMapClosure cl(_cm, this);
1720 iterate(&cl);
1721 }
1722 #endif // PRODUCT
1724 void retire() {
1725 guarantee(use_local_bitmaps, "invariant");
1726 assert(fields_well_formed(), "invariant");
1728 if (_start_word != NULL) {
1729 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1731 // this means that the bitmap was set up for the GCLab
1732 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1734 mark_bitmap->mostly_disjoint_range_union(this,
1735 0, // always start from the start of the bitmap
1736 _start_word,
1737 gclab_real_word_size());
1738 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1740 #ifndef PRODUCT
1741 if (use_local_bitmaps && verify_local_bitmaps)
1742 verify();
1743 #endif // PRODUCT
1744 } else {
1745 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1746 }
1747 }
1749 size_t bitmap_size_in_words() const {
1750 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1751 }
1753 };
1755 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1756 private:
1757 bool _retired;
1758 bool _during_marking;
1759 GCLabBitMap _bitmap;
1761 public:
1762 G1ParGCAllocBuffer(size_t gclab_word_size) :
1763 ParGCAllocBuffer(gclab_word_size),
1764 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1765 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1766 _retired(false)
1767 { }
1769 inline bool mark(HeapWord* addr) {
1770 guarantee(use_local_bitmaps, "invariant");
1771 assert(_during_marking, "invariant");
1772 return _bitmap.mark(addr);
1773 }
1775 inline void set_buf(HeapWord* buf) {
1776 if (use_local_bitmaps && _during_marking)
1777 _bitmap.set_buffer(buf);
1778 ParGCAllocBuffer::set_buf(buf);
1779 _retired = false;
1780 }
1782 inline void retire(bool end_of_gc, bool retain) {
1783 if (_retired)
1784 return;
1785 if (use_local_bitmaps && _during_marking) {
1786 _bitmap.retire();
1787 }
1788 ParGCAllocBuffer::retire(end_of_gc, retain);
1789 _retired = true;
1790 }
1791 };
1793 class G1ParScanThreadState : public StackObj {
1794 protected:
1795 G1CollectedHeap* _g1h;
1796 RefToScanQueue* _refs;
1797 DirtyCardQueue _dcq;
1798 CardTableModRefBS* _ct_bs;
1799 G1RemSet* _g1_rem;
1801 G1ParGCAllocBuffer _surviving_alloc_buffer;
1802 G1ParGCAllocBuffer _tenured_alloc_buffer;
1803 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1804 ageTable _age_table;
1806 size_t _alloc_buffer_waste;
1807 size_t _undo_waste;
1809 OopsInHeapRegionClosure* _evac_failure_cl;
1810 G1ParScanHeapEvacClosure* _evac_cl;
1811 G1ParScanPartialArrayClosure* _partial_scan_cl;
1813 int _hash_seed;
1814 int _queue_num;
1816 size_t _term_attempts;
1818 double _start;
1819 double _start_strong_roots;
1820 double _strong_roots_time;
1821 double _start_term;
1822 double _term_time;
1824 // Map from young-age-index (0 == not young, 1 is youngest) to
1825 // surviving words. base is what we get back from the malloc call
1826 size_t* _surviving_young_words_base;
1827 // this points into the array, as we use the first few entries for padding
1828 size_t* _surviving_young_words;
1830 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1832 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1834 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1836 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1837 CardTableModRefBS* ctbs() { return _ct_bs; }
1839 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1840 if (!from->is_survivor()) {
1841 _g1_rem->par_write_ref(from, p, tid);
1842 }
1843 }
1845 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1846 // If the new value of the field points to the same region or
1847 // is the to-space, we don't need to include it in the Rset updates.
1848 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1849 size_t card_index = ctbs()->index_for(p);
1850 // If the card hasn't been added to the buffer, do it.
1851 if (ctbs()->mark_card_deferred(card_index)) {
1852 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1853 }
1854 }
1855 }
1857 public:
1858 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1860 ~G1ParScanThreadState() {
1861 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1862 }
1864 RefToScanQueue* refs() { return _refs; }
1865 ageTable* age_table() { return &_age_table; }
1867 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1868 return _alloc_buffers[purpose];
1869 }
1871 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1872 size_t undo_waste() const { return _undo_waste; }
1874 #ifdef ASSERT
1875 bool verify_ref(narrowOop* ref) const;
1876 bool verify_ref(oop* ref) const;
1877 bool verify_task(StarTask ref) const;
1878 #endif // ASSERT
1880 template <class T> void push_on_queue(T* ref) {
1881 assert(verify_ref(ref), "sanity");
1882 refs()->push(ref);
1883 }
1885 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1886 if (G1DeferredRSUpdate) {
1887 deferred_rs_update(from, p, tid);
1888 } else {
1889 immediate_rs_update(from, p, tid);
1890 }
1891 }
1893 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1895 HeapWord* obj = NULL;
1896 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1897 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1898 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1899 assert(gclab_word_size == alloc_buf->word_sz(),
1900 "dynamic resizing is not supported");
1901 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1902 alloc_buf->retire(false, false);
1904 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1905 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1906 // Otherwise.
1907 alloc_buf->set_buf(buf);
1909 obj = alloc_buf->allocate(word_sz);
1910 assert(obj != NULL, "buffer was definitely big enough...");
1911 } else {
1912 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1913 }
1914 return obj;
1915 }
1917 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1918 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1919 if (obj != NULL) return obj;
1920 return allocate_slow(purpose, word_sz);
1921 }
1923 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1924 if (alloc_buffer(purpose)->contains(obj)) {
1925 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1926 "should contain whole object");
1927 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1928 } else {
1929 CollectedHeap::fill_with_object(obj, word_sz);
1930 add_to_undo_waste(word_sz);
1931 }
1932 }
1934 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1935 _evac_failure_cl = evac_failure_cl;
1936 }
1937 OopsInHeapRegionClosure* evac_failure_closure() {
1938 return _evac_failure_cl;
1939 }
1941 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1942 _evac_cl = evac_cl;
1943 }
1945 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1946 _partial_scan_cl = partial_scan_cl;
1947 }
1949 int* hash_seed() { return &_hash_seed; }
1950 int queue_num() { return _queue_num; }
1952 size_t term_attempts() const { return _term_attempts; }
1953 void note_term_attempt() { _term_attempts++; }
1955 void start_strong_roots() {
1956 _start_strong_roots = os::elapsedTime();
1957 }
1958 void end_strong_roots() {
1959 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1960 }
1961 double strong_roots_time() const { return _strong_roots_time; }
1963 void start_term_time() {
1964 note_term_attempt();
1965 _start_term = os::elapsedTime();
1966 }
1967 void end_term_time() {
1968 _term_time += (os::elapsedTime() - _start_term);
1969 }
1970 double term_time() const { return _term_time; }
1972 double elapsed_time() const {
1973 return os::elapsedTime() - _start;
1974 }
1976 static void
1977 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1978 void
1979 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1981 size_t* surviving_young_words() {
1982 // We add on to hide entry 0 which accumulates surviving words for
1983 // age -1 regions (i.e. non-young ones)
1984 return _surviving_young_words;
1985 }
1987 void retire_alloc_buffers() {
1988 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1989 size_t waste = _alloc_buffers[ap]->words_remaining();
1990 add_to_alloc_buffer_waste(waste);
1991 _alloc_buffers[ap]->retire(true, false);
1992 }
1993 }
1995 template <class T> void deal_with_reference(T* ref_to_scan) {
1996 if (has_partial_array_mask(ref_to_scan)) {
1997 _partial_scan_cl->do_oop_nv(ref_to_scan);
1998 } else {
1999 // Note: we can use "raw" versions of "region_containing" because
2000 // "obj_to_scan" is definitely in the heap, and is not in a
2001 // humongous region.
2002 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2003 _evac_cl->set_region(r);
2004 _evac_cl->do_oop_nv(ref_to_scan);
2005 }
2006 }
2008 void deal_with_reference(StarTask ref) {
2009 assert(verify_task(ref), "sanity");
2010 if (ref.is_narrow()) {
2011 deal_with_reference((narrowOop*)ref);
2012 } else {
2013 deal_with_reference((oop*)ref);
2014 }
2015 }
2017 public:
2018 void trim_queue();
2019 };
2021 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP