Thu, 16 Jun 2011 15:51:57 -0400
6994322: Remove the is_tlab and is_noref / is_large_noref parameters from the CollectedHeap
Summary: Remove two unused parameters from the mem_allocate() method and update its uses accordingly.
Reviewed-by: stefank, johnc
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
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/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1RemSet.hpp"
31 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.hpp"
33 #include "gc_implementation/g1/heapRegionSets.hpp"
34 #include "gc_implementation/shared/hSpaceCounters.hpp"
35 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
36 #include "memory/barrierSet.hpp"
37 #include "memory/memRegion.hpp"
38 #include "memory/sharedHeap.hpp"
40 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
41 // It uses the "Garbage First" heap organization and algorithm, which
42 // may combine concurrent marking with parallel, incremental compaction of
43 // heap subsets that will yield large amounts of garbage.
45 class HeapRegion;
46 class HRRSCleanupTask;
47 class PermanentGenerationSpec;
48 class GenerationSpec;
49 class OopsInHeapRegionClosure;
50 class G1ScanHeapEvacClosure;
51 class ObjectClosure;
52 class SpaceClosure;
53 class CompactibleSpaceClosure;
54 class Space;
55 class G1CollectorPolicy;
56 class GenRemSet;
57 class G1RemSet;
58 class HeapRegionRemSetIterator;
59 class ConcurrentMark;
60 class ConcurrentMarkThread;
61 class ConcurrentG1Refine;
62 class GenerationCounters;
64 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
65 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
67 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
68 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
70 enum GCAllocPurpose {
71 GCAllocForTenured,
72 GCAllocForSurvived,
73 GCAllocPurposeCount
74 };
76 class YoungList : public CHeapObj {
77 private:
78 G1CollectedHeap* _g1h;
80 HeapRegion* _head;
82 HeapRegion* _survivor_head;
83 HeapRegion* _survivor_tail;
85 HeapRegion* _curr;
87 size_t _length;
88 size_t _survivor_length;
90 size_t _last_sampled_rs_lengths;
91 size_t _sampled_rs_lengths;
93 void empty_list(HeapRegion* list);
95 public:
96 YoungList(G1CollectedHeap* g1h);
98 void push_region(HeapRegion* hr);
99 void add_survivor_region(HeapRegion* hr);
101 void empty_list();
102 bool is_empty() { return _length == 0; }
103 size_t length() { return _length; }
104 size_t survivor_length() { return _survivor_length; }
106 // Currently we do not keep track of the used byte sum for the
107 // young list and the survivors and it'd be quite a lot of work to
108 // do so. When we'll eventually replace the young list with
109 // instances of HeapRegionLinkedList we'll get that for free. So,
110 // we'll report the more accurate information then.
111 size_t eden_used_bytes() {
112 assert(length() >= survivor_length(), "invariant");
113 return (length() - survivor_length()) * HeapRegion::GrainBytes;
114 }
115 size_t survivor_used_bytes() {
116 return survivor_length() * HeapRegion::GrainBytes;
117 }
119 void rs_length_sampling_init();
120 bool rs_length_sampling_more();
121 void rs_length_sampling_next();
123 void reset_sampled_info() {
124 _last_sampled_rs_lengths = 0;
125 }
126 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
128 // for development purposes
129 void reset_auxilary_lists();
130 void clear() { _head = NULL; _length = 0; }
132 void clear_survivors() {
133 _survivor_head = NULL;
134 _survivor_tail = NULL;
135 _survivor_length = 0;
136 }
138 HeapRegion* first_region() { return _head; }
139 HeapRegion* first_survivor_region() { return _survivor_head; }
140 HeapRegion* last_survivor_region() { return _survivor_tail; }
142 // debugging
143 bool check_list_well_formed();
144 bool check_list_empty(bool check_sample = true);
145 void print();
146 };
148 class MutatorAllocRegion : public G1AllocRegion {
149 protected:
150 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
151 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
152 public:
153 MutatorAllocRegion()
154 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
155 };
157 class RefineCardTableEntryClosure;
158 class G1CollectedHeap : public SharedHeap {
159 friend class VM_G1CollectForAllocation;
160 friend class VM_GenCollectForPermanentAllocation;
161 friend class VM_G1CollectFull;
162 friend class VM_G1IncCollectionPause;
163 friend class VMStructs;
164 friend class MutatorAllocRegion;
166 // Closures used in implementation.
167 friend class G1ParCopyHelper;
168 friend class G1IsAliveClosure;
169 friend class G1EvacuateFollowersClosure;
170 friend class G1ParScanThreadState;
171 friend class G1ParScanClosureSuper;
172 friend class G1ParEvacuateFollowersClosure;
173 friend class G1ParTask;
174 friend class G1FreeGarbageRegionClosure;
175 friend class RefineCardTableEntryClosure;
176 friend class G1PrepareCompactClosure;
177 friend class RegionSorter;
178 friend class RegionResetter;
179 friend class CountRCClosure;
180 friend class EvacPopObjClosure;
181 friend class G1ParCleanupCTTask;
183 // Other related classes.
184 friend class G1MarkSweep;
186 private:
187 // The one and only G1CollectedHeap, so static functions can find it.
188 static G1CollectedHeap* _g1h;
190 static size_t _humongous_object_threshold_in_words;
192 // Storage for the G1 heap (excludes the permanent generation).
193 VirtualSpace _g1_storage;
194 MemRegion _g1_reserved;
196 // The part of _g1_storage that is currently committed.
197 MemRegion _g1_committed;
199 // The master free list. It will satisfy all new region allocations.
200 MasterFreeRegionList _free_list;
202 // The secondary free list which contains regions that have been
203 // freed up during the cleanup process. This will be appended to the
204 // master free list when appropriate.
205 SecondaryFreeRegionList _secondary_free_list;
207 // It keeps track of the humongous regions.
208 MasterHumongousRegionSet _humongous_set;
210 // The number of regions we could create by expansion.
211 size_t _expansion_regions;
213 // The block offset table for the G1 heap.
214 G1BlockOffsetSharedArray* _bot_shared;
216 // Move all of the regions off the free lists, then rebuild those free
217 // lists, before and after full GC.
218 void tear_down_region_lists();
219 void rebuild_region_lists();
221 // The sequence of all heap regions in the heap.
222 HeapRegionSeq _hrs;
224 // Alloc region used to satisfy mutator allocation requests.
225 MutatorAllocRegion _mutator_alloc_region;
227 // It resets the mutator alloc region before new allocations can take place.
228 void init_mutator_alloc_region();
230 // It releases the mutator alloc region.
231 void release_mutator_alloc_region();
233 void abandon_gc_alloc_regions();
235 // The to-space memory regions into which objects are being copied during
236 // a GC.
237 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
238 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
239 // These are the regions, one per GCAllocPurpose, that are half-full
240 // at the end of a collection and that we want to reuse during the
241 // next collection.
242 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
243 // This specifies whether we will keep the last half-full region at
244 // the end of a collection so that it can be reused during the next
245 // collection (this is specified per GCAllocPurpose)
246 bool _retain_gc_alloc_region[GCAllocPurposeCount];
248 // A list of the regions that have been set to be alloc regions in the
249 // current collection.
250 HeapRegion* _gc_alloc_region_list;
252 // Helper for monitoring and management support.
253 G1MonitoringSupport* _g1mm;
255 // Determines PLAB size for a particular allocation purpose.
256 static size_t desired_plab_sz(GCAllocPurpose purpose);
258 // When called by par thread, requires the FreeList_lock to be held.
259 void push_gc_alloc_region(HeapRegion* hr);
261 // This should only be called single-threaded. Undeclares all GC alloc
262 // regions.
263 void forget_alloc_region_list();
265 // Should be used to set an alloc region, because there's other
266 // associated bookkeeping.
267 void set_gc_alloc_region(int purpose, HeapRegion* r);
269 // Check well-formedness of alloc region list.
270 bool check_gc_alloc_regions();
272 // Outside of GC pauses, the number of bytes used in all regions other
273 // than the current allocation region.
274 size_t _summary_bytes_used;
276 // This is used for a quick test on whether a reference points into
277 // the collection set or not. Basically, we have an array, with one
278 // byte per region, and that byte denotes whether the corresponding
279 // region is in the collection set or not. The entry corresponding
280 // the bottom of the heap, i.e., region 0, is pointed to by
281 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
282 // biased so that it actually points to address 0 of the address
283 // space, to make the test as fast as possible (we can simply shift
284 // the address to address into it, instead of having to subtract the
285 // bottom of the heap from the address before shifting it; basically
286 // it works in the same way the card table works).
287 bool* _in_cset_fast_test;
289 // The allocated array used for the fast test on whether a reference
290 // points into the collection set or not. This field is also used to
291 // free the array.
292 bool* _in_cset_fast_test_base;
294 // The length of the _in_cset_fast_test_base array.
295 size_t _in_cset_fast_test_length;
297 volatile unsigned _gc_time_stamp;
299 size_t* _surviving_young_words;
301 void setup_surviving_young_words();
302 void update_surviving_young_words(size_t* surv_young_words);
303 void cleanup_surviving_young_words();
305 // It decides whether an explicit GC should start a concurrent cycle
306 // instead of doing a STW GC. Currently, a concurrent cycle is
307 // explicitly started if:
308 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
309 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
310 bool should_do_concurrent_full_gc(GCCause::Cause cause);
312 // Keeps track of how many "full collections" (i.e., Full GCs or
313 // concurrent cycles) we have completed. The number of them we have
314 // started is maintained in _total_full_collections in CollectedHeap.
315 volatile unsigned int _full_collections_completed;
317 // This is a non-product method that is helpful for testing. It is
318 // called at the end of a GC and artificially expands the heap by
319 // allocating a number of dead regions. This way we can induce very
320 // frequent marking cycles and stress the cleanup / concurrent
321 // cleanup code more (as all the regions that will be allocated by
322 // this method will be found dead by the marking cycle).
323 void allocate_dummy_regions() PRODUCT_RETURN;
325 // These are macros so that, if the assert fires, we get the correct
326 // line number, file, etc.
328 #define heap_locking_asserts_err_msg(_extra_message_) \
329 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
330 (_extra_message_), \
331 BOOL_TO_STR(Heap_lock->owned_by_self()), \
332 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
333 BOOL_TO_STR(Thread::current()->is_VM_thread()))
335 #define assert_heap_locked() \
336 do { \
337 assert(Heap_lock->owned_by_self(), \
338 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
339 } while (0)
341 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
342 do { \
343 assert(Heap_lock->owned_by_self() || \
344 (SafepointSynchronize::is_at_safepoint() && \
345 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
346 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
347 "should be at a safepoint")); \
348 } while (0)
350 #define assert_heap_locked_and_not_at_safepoint() \
351 do { \
352 assert(Heap_lock->owned_by_self() && \
353 !SafepointSynchronize::is_at_safepoint(), \
354 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
355 "should not be at a safepoint")); \
356 } while (0)
358 #define assert_heap_not_locked() \
359 do { \
360 assert(!Heap_lock->owned_by_self(), \
361 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
362 } while (0)
364 #define assert_heap_not_locked_and_not_at_safepoint() \
365 do { \
366 assert(!Heap_lock->owned_by_self() && \
367 !SafepointSynchronize::is_at_safepoint(), \
368 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
369 "should not be at a safepoint")); \
370 } while (0)
372 #define assert_at_safepoint(_should_be_vm_thread_) \
373 do { \
374 assert(SafepointSynchronize::is_at_safepoint() && \
375 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
376 heap_locking_asserts_err_msg("should be at a safepoint")); \
377 } while (0)
379 #define assert_not_at_safepoint() \
380 do { \
381 assert(!SafepointSynchronize::is_at_safepoint(), \
382 heap_locking_asserts_err_msg("should not be at a safepoint")); \
383 } while (0)
385 protected:
387 // Returns "true" iff none of the gc alloc regions have any allocations
388 // since the last call to "save_marks".
389 bool all_alloc_regions_no_allocs_since_save_marks();
390 // Perform finalization stuff on all allocation regions.
391 void retire_all_alloc_regions();
393 // The number of regions allocated to hold humongous objects.
394 int _num_humongous_regions;
395 YoungList* _young_list;
397 // The current policy object for the collector.
398 G1CollectorPolicy* _g1_policy;
400 // This is the second level of trying to allocate a new region. If
401 // new_region() didn't find a region on the free_list, this call will
402 // check whether there's anything available on the
403 // secondary_free_list and/or wait for more regions to appear on
404 // that list, if _free_regions_coming is set.
405 HeapRegion* new_region_try_secondary_free_list();
407 // Try to allocate a single non-humongous HeapRegion sufficient for
408 // an allocation of the given word_size. If do_expand is true,
409 // attempt to expand the heap if necessary to satisfy the allocation
410 // request.
411 HeapRegion* new_region(size_t word_size, bool do_expand);
413 // Try to allocate a new region to be used for allocation by
414 // a GC thread. It will try to expand the heap if no region is
415 // available.
416 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
418 // Attempt to satisfy a humongous allocation request of the given
419 // size by finding a contiguous set of free regions of num_regions
420 // length and remove them from the master free list. Return the
421 // index of the first region or G1_NULL_HRS_INDEX if the search
422 // was unsuccessful.
423 size_t humongous_obj_allocate_find_first(size_t num_regions,
424 size_t word_size);
426 // Initialize a contiguous set of free regions of length num_regions
427 // and starting at index first so that they appear as a single
428 // humongous region.
429 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
430 size_t num_regions,
431 size_t word_size);
433 // Attempt to allocate a humongous object of the given size. Return
434 // NULL if unsuccessful.
435 HeapWord* humongous_obj_allocate(size_t word_size);
437 // The following two methods, allocate_new_tlab() and
438 // mem_allocate(), are the two main entry points from the runtime
439 // into the G1's allocation routines. They have the following
440 // assumptions:
441 //
442 // * They should both be called outside safepoints.
443 //
444 // * They should both be called without holding the Heap_lock.
445 //
446 // * All allocation requests for new TLABs should go to
447 // allocate_new_tlab().
448 //
449 // * All non-TLAB allocation requests should go to mem_allocate().
450 //
451 // * If either call cannot satisfy the allocation request using the
452 // current allocating region, they will try to get a new one. If
453 // this fails, they will attempt to do an evacuation pause and
454 // retry the allocation.
455 //
456 // * If all allocation attempts fail, even after trying to schedule
457 // an evacuation pause, allocate_new_tlab() will return NULL,
458 // whereas mem_allocate() will attempt a heap expansion and/or
459 // schedule a Full GC.
460 //
461 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
462 // should never be called with word_size being humongous. All
463 // humongous allocation requests should go to mem_allocate() which
464 // will satisfy them with a special path.
466 virtual HeapWord* allocate_new_tlab(size_t word_size);
468 virtual HeapWord* mem_allocate(size_t word_size,
469 bool* gc_overhead_limit_was_exceeded);
471 // The following three methods take a gc_count_before_ret
472 // parameter which is used to return the GC count if the method
473 // returns NULL. Given that we are required to read the GC count
474 // while holding the Heap_lock, and these paths will take the
475 // Heap_lock at some point, it's easier to get them to read the GC
476 // count while holding the Heap_lock before they return NULL instead
477 // of the caller (namely: mem_allocate()) having to also take the
478 // Heap_lock just to read the GC count.
480 // First-level mutator allocation attempt: try to allocate out of
481 // the mutator alloc region without taking the Heap_lock. This
482 // should only be used for non-humongous allocations.
483 inline HeapWord* attempt_allocation(size_t word_size,
484 unsigned int* gc_count_before_ret);
486 // Second-level mutator allocation attempt: take the Heap_lock and
487 // retry the allocation attempt, potentially scheduling a GC
488 // pause. This should only be used for non-humongous allocations.
489 HeapWord* attempt_allocation_slow(size_t word_size,
490 unsigned int* gc_count_before_ret);
492 // Takes the Heap_lock and attempts a humongous allocation. It can
493 // potentially schedule a GC pause.
494 HeapWord* attempt_allocation_humongous(size_t word_size,
495 unsigned int* gc_count_before_ret);
497 // Allocation attempt that should be called during safepoints (e.g.,
498 // at the end of a successful GC). expect_null_mutator_alloc_region
499 // specifies whether the mutator alloc region is expected to be NULL
500 // or not.
501 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
502 bool expect_null_mutator_alloc_region);
504 // It dirties the cards that cover the block so that so that the post
505 // write barrier never queues anything when updating objects on this
506 // block. It is assumed (and in fact we assert) that the block
507 // belongs to a young region.
508 inline void dirty_young_block(HeapWord* start, size_t word_size);
510 // Allocate blocks during garbage collection. Will ensure an
511 // allocation region, either by picking one or expanding the
512 // heap, and then allocate a block of the given size. The block
513 // may not be a humongous - it must fit into a single heap region.
514 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
516 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
517 HeapRegion* alloc_region,
518 bool par,
519 size_t word_size);
521 // Ensure that no further allocations can happen in "r", bearing in mind
522 // that parallel threads might be attempting allocations.
523 void par_allocate_remaining_space(HeapRegion* r);
525 // Retires an allocation region when it is full or at the end of a
526 // GC pause.
527 void retire_alloc_region(HeapRegion* alloc_region, bool par);
529 // These two methods are the "callbacks" from the G1AllocRegion class.
531 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
532 void retire_mutator_alloc_region(HeapRegion* alloc_region,
533 size_t allocated_bytes);
535 // - if explicit_gc is true, the GC is for a System.gc() or a heap
536 // inspection request and should collect the entire heap
537 // - if clear_all_soft_refs is true, all soft references should be
538 // cleared during the GC
539 // - if explicit_gc is false, word_size describes the allocation that
540 // the GC should attempt (at least) to satisfy
541 // - it returns false if it is unable to do the collection due to the
542 // GC locker being active, true otherwise
543 bool do_collection(bool explicit_gc,
544 bool clear_all_soft_refs,
545 size_t word_size);
547 // Callback from VM_G1CollectFull operation.
548 // Perform a full collection.
549 void do_full_collection(bool clear_all_soft_refs);
551 // Resize the heap if necessary after a full collection. If this is
552 // after a collect-for allocation, "word_size" is the allocation size,
553 // and will be considered part of the used portion of the heap.
554 void resize_if_necessary_after_full_collection(size_t word_size);
556 // Callback from VM_G1CollectForAllocation operation.
557 // This function does everything necessary/possible to satisfy a
558 // failed allocation request (including collection, expansion, etc.)
559 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
561 // Attempting to expand the heap sufficiently
562 // to support an allocation of the given "word_size". If
563 // successful, perform the allocation and return the address of the
564 // allocated block, or else "NULL".
565 HeapWord* expand_and_allocate(size_t word_size);
567 public:
569 G1MonitoringSupport* g1mm() { return _g1mm; }
571 // Expand the garbage-first heap by at least the given size (in bytes!).
572 // Returns true if the heap was expanded by the requested amount;
573 // false otherwise.
574 // (Rounds up to a HeapRegion boundary.)
575 bool expand(size_t expand_bytes);
577 // Do anything common to GC's.
578 virtual void gc_prologue(bool full);
579 virtual void gc_epilogue(bool full);
581 // We register a region with the fast "in collection set" test. We
582 // simply set to true the array slot corresponding to this region.
583 void register_region_with_in_cset_fast_test(HeapRegion* r) {
584 assert(_in_cset_fast_test_base != NULL, "sanity");
585 assert(r->in_collection_set(), "invariant");
586 size_t index = r->hrs_index();
587 assert(index < _in_cset_fast_test_length, "invariant");
588 assert(!_in_cset_fast_test_base[index], "invariant");
589 _in_cset_fast_test_base[index] = true;
590 }
592 // This is a fast test on whether a reference points into the
593 // collection set or not. It does not assume that the reference
594 // points into the heap; if it doesn't, it will return false.
595 bool in_cset_fast_test(oop obj) {
596 assert(_in_cset_fast_test != NULL, "sanity");
597 if (_g1_committed.contains((HeapWord*) obj)) {
598 // no need to subtract the bottom of the heap from obj,
599 // _in_cset_fast_test is biased
600 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
601 bool ret = _in_cset_fast_test[index];
602 // let's make sure the result is consistent with what the slower
603 // test returns
604 assert( ret || !obj_in_cs(obj), "sanity");
605 assert(!ret || obj_in_cs(obj), "sanity");
606 return ret;
607 } else {
608 return false;
609 }
610 }
612 void clear_cset_fast_test() {
613 assert(_in_cset_fast_test_base != NULL, "sanity");
614 memset(_in_cset_fast_test_base, false,
615 _in_cset_fast_test_length * sizeof(bool));
616 }
618 // This is called at the end of either a concurrent cycle or a Full
619 // GC to update the number of full collections completed. Those two
620 // can happen in a nested fashion, i.e., we start a concurrent
621 // cycle, a Full GC happens half-way through it which ends first,
622 // and then the cycle notices that a Full GC happened and ends
623 // too. The concurrent parameter is a boolean to help us do a bit
624 // tighter consistency checking in the method. If concurrent is
625 // false, the caller is the inner caller in the nesting (i.e., the
626 // Full GC). If concurrent is true, the caller is the outer caller
627 // in this nesting (i.e., the concurrent cycle). Further nesting is
628 // not currently supported. The end of the this call also notifies
629 // the FullGCCount_lock in case a Java thread is waiting for a full
630 // GC to happen (e.g., it called System.gc() with
631 // +ExplicitGCInvokesConcurrent).
632 void increment_full_collections_completed(bool concurrent);
634 unsigned int full_collections_completed() {
635 return _full_collections_completed;
636 }
638 protected:
640 // Shrink the garbage-first heap by at most the given size (in bytes!).
641 // (Rounds down to a HeapRegion boundary.)
642 virtual void shrink(size_t expand_bytes);
643 void shrink_helper(size_t expand_bytes);
645 #if TASKQUEUE_STATS
646 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
647 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
648 void reset_taskqueue_stats();
649 #endif // TASKQUEUE_STATS
651 // Schedule the VM operation that will do an evacuation pause to
652 // satisfy an allocation request of word_size. *succeeded will
653 // return whether the VM operation was successful (it did do an
654 // evacuation pause) or not (another thread beat us to it or the GC
655 // locker was active). Given that we should not be holding the
656 // Heap_lock when we enter this method, we will pass the
657 // gc_count_before (i.e., total_collections()) as a parameter since
658 // it has to be read while holding the Heap_lock. Currently, both
659 // methods that call do_collection_pause() release the Heap_lock
660 // before the call, so it's easy to read gc_count_before just before.
661 HeapWord* do_collection_pause(size_t word_size,
662 unsigned int gc_count_before,
663 bool* succeeded);
665 // The guts of the incremental collection pause, executed by the vm
666 // thread. It returns false if it is unable to do the collection due
667 // to the GC locker being active, true otherwise
668 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
670 // Actually do the work of evacuating the collection set.
671 void evacuate_collection_set();
673 // The g1 remembered set of the heap.
674 G1RemSet* _g1_rem_set;
675 // And it's mod ref barrier set, used to track updates for the above.
676 ModRefBarrierSet* _mr_bs;
678 // A set of cards that cover the objects for which the Rsets should be updated
679 // concurrently after the collection.
680 DirtyCardQueueSet _dirty_card_queue_set;
682 // The Heap Region Rem Set Iterator.
683 HeapRegionRemSetIterator** _rem_set_iterator;
685 // The closure used to refine a single card.
686 RefineCardTableEntryClosure* _refine_cte_cl;
688 // A function to check the consistency of dirty card logs.
689 void check_ct_logs_at_safepoint();
691 // A DirtyCardQueueSet that is used to hold cards that contain
692 // references into the current collection set. This is used to
693 // update the remembered sets of the regions in the collection
694 // set in the event of an evacuation failure.
695 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
697 // After a collection pause, make the regions in the CS into free
698 // regions.
699 void free_collection_set(HeapRegion* cs_head);
701 // Abandon the current collection set without recording policy
702 // statistics or updating free lists.
703 void abandon_collection_set(HeapRegion* cs_head);
705 // Applies "scan_non_heap_roots" to roots outside the heap,
706 // "scan_rs" to roots inside the heap (having done "set_region" to
707 // indicate the region in which the root resides), and does "scan_perm"
708 // (setting the generation to the perm generation.) If "scan_rs" is
709 // NULL, then this step is skipped. The "worker_i"
710 // param is for use with parallel roots processing, and should be
711 // the "i" of the calling parallel worker thread's work(i) function.
712 // In the sequential case this param will be ignored.
713 void g1_process_strong_roots(bool collecting_perm_gen,
714 SharedHeap::ScanningOption so,
715 OopClosure* scan_non_heap_roots,
716 OopsInHeapRegionClosure* scan_rs,
717 OopsInGenClosure* scan_perm,
718 int worker_i);
720 // Apply "blk" to all the weak roots of the system. These include
721 // JNI weak roots, the code cache, system dictionary, symbol table,
722 // string table, and referents of reachable weak refs.
723 void g1_process_weak_roots(OopClosure* root_closure,
724 OopClosure* non_root_closure);
726 // Invoke "save_marks" on all heap regions.
727 void save_marks();
729 // Frees a non-humongous region by initializing its contents and
730 // adding it to the free list that's passed as a parameter (this is
731 // usually a local list which will be appended to the master free
732 // list later). The used bytes of freed regions are accumulated in
733 // pre_used. If par is true, the region's RSet will not be freed
734 // up. The assumption is that this will be done later.
735 void free_region(HeapRegion* hr,
736 size_t* pre_used,
737 FreeRegionList* free_list,
738 bool par);
740 // Frees a humongous region by collapsing it into individual regions
741 // and calling free_region() for each of them. The freed regions
742 // will be added to the free list that's passed as a parameter (this
743 // is usually a local list which will be appended to the master free
744 // list later). The used bytes of freed regions are accumulated in
745 // pre_used. If par is true, the region's RSet will not be freed
746 // up. The assumption is that this will be done later.
747 void free_humongous_region(HeapRegion* hr,
748 size_t* pre_used,
749 FreeRegionList* free_list,
750 HumongousRegionSet* humongous_proxy_set,
751 bool par);
753 // Notifies all the necessary spaces that the committed space has
754 // been updated (either expanded or shrunk). It should be called
755 // after _g1_storage is updated.
756 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
758 // The concurrent marker (and the thread it runs in.)
759 ConcurrentMark* _cm;
760 ConcurrentMarkThread* _cmThread;
761 bool _mark_in_progress;
763 // The concurrent refiner.
764 ConcurrentG1Refine* _cg1r;
766 // The parallel task queues
767 RefToScanQueueSet *_task_queues;
769 // True iff a evacuation has failed in the current collection.
770 bool _evacuation_failed;
772 // Set the attribute indicating whether evacuation has failed in the
773 // current collection.
774 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
776 // Failed evacuations cause some logical from-space objects to have
777 // forwarding pointers to themselves. Reset them.
778 void remove_self_forwarding_pointers();
780 // When one is non-null, so is the other. Together, they each pair is
781 // an object with a preserved mark, and its mark value.
782 GrowableArray<oop>* _objs_with_preserved_marks;
783 GrowableArray<markOop>* _preserved_marks_of_objs;
785 // Preserve the mark of "obj", if necessary, in preparation for its mark
786 // word being overwritten with a self-forwarding-pointer.
787 void preserve_mark_if_necessary(oop obj, markOop m);
789 // The stack of evac-failure objects left to be scanned.
790 GrowableArray<oop>* _evac_failure_scan_stack;
791 // The closure to apply to evac-failure objects.
793 OopsInHeapRegionClosure* _evac_failure_closure;
794 // Set the field above.
795 void
796 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
797 _evac_failure_closure = evac_failure_closure;
798 }
800 // Push "obj" on the scan stack.
801 void push_on_evac_failure_scan_stack(oop obj);
802 // Process scan stack entries until the stack is empty.
803 void drain_evac_failure_scan_stack();
804 // True iff an invocation of "drain_scan_stack" is in progress; to
805 // prevent unnecessary recursion.
806 bool _drain_in_progress;
808 // Do any necessary initialization for evacuation-failure handling.
809 // "cl" is the closure that will be used to process evac-failure
810 // objects.
811 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
812 // Do any necessary cleanup for evacuation-failure handling data
813 // structures.
814 void finalize_for_evac_failure();
816 // An attempt to evacuate "obj" has failed; take necessary steps.
817 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
818 void handle_evacuation_failure_common(oop obj, markOop m);
820 // Ensure that the relevant gc_alloc regions are set.
821 void get_gc_alloc_regions();
822 // We're done with GC alloc regions. We are going to tear down the
823 // gc alloc list and remove the gc alloc tag from all the regions on
824 // that list. However, we will also retain the last (i.e., the one
825 // that is half-full) GC alloc region, per GCAllocPurpose, for
826 // possible reuse during the next collection, provided
827 // _retain_gc_alloc_region[] indicates that it should be the
828 // case. Said regions are kept in the _retained_gc_alloc_regions[]
829 // array. If the parameter totally is set, we will not retain any
830 // regions, irrespective of what _retain_gc_alloc_region[]
831 // indicates.
832 void release_gc_alloc_regions(bool totally);
833 #ifndef PRODUCT
834 // Useful for debugging.
835 void print_gc_alloc_regions();
836 #endif // !PRODUCT
838 // Instance of the concurrent mark is_alive closure for embedding
839 // into the reference processor as the is_alive_non_header. This
840 // prevents unnecessary additions to the discovered lists during
841 // concurrent discovery.
842 G1CMIsAliveClosure _is_alive_closure;
844 // ("Weak") Reference processing support
845 ReferenceProcessor* _ref_processor;
847 enum G1H_process_strong_roots_tasks {
848 G1H_PS_mark_stack_oops_do,
849 G1H_PS_refProcessor_oops_do,
850 // Leave this one last.
851 G1H_PS_NumElements
852 };
854 SubTasksDone* _process_strong_tasks;
856 volatile bool _free_regions_coming;
858 public:
860 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
862 void set_refine_cte_cl_concurrency(bool concurrent);
864 RefToScanQueue *task_queue(int i) const;
866 // A set of cards where updates happened during the GC
867 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
869 // A DirtyCardQueueSet that is used to hold cards that contain
870 // references into the current collection set. This is used to
871 // update the remembered sets of the regions in the collection
872 // set in the event of an evacuation failure.
873 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
874 { return _into_cset_dirty_card_queue_set; }
876 // Create a G1CollectedHeap with the specified policy.
877 // Must call the initialize method afterwards.
878 // May not return if something goes wrong.
879 G1CollectedHeap(G1CollectorPolicy* policy);
881 // Initialize the G1CollectedHeap to have the initial and
882 // maximum sizes, permanent generation, and remembered and barrier sets
883 // specified by the policy object.
884 jint initialize();
886 virtual void ref_processing_init();
888 void set_par_threads(int t) {
889 SharedHeap::set_par_threads(t);
890 _process_strong_tasks->set_n_threads(t);
891 }
893 virtual CollectedHeap::Name kind() const {
894 return CollectedHeap::G1CollectedHeap;
895 }
897 // The current policy object for the collector.
898 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
900 // Adaptive size policy. No such thing for g1.
901 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
903 // The rem set and barrier set.
904 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
905 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
907 // The rem set iterator.
908 HeapRegionRemSetIterator* rem_set_iterator(int i) {
909 return _rem_set_iterator[i];
910 }
912 HeapRegionRemSetIterator* rem_set_iterator() {
913 return _rem_set_iterator[0];
914 }
916 unsigned get_gc_time_stamp() {
917 return _gc_time_stamp;
918 }
920 void reset_gc_time_stamp() {
921 _gc_time_stamp = 0;
922 OrderAccess::fence();
923 }
925 void increment_gc_time_stamp() {
926 ++_gc_time_stamp;
927 OrderAccess::fence();
928 }
930 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
931 DirtyCardQueue* into_cset_dcq,
932 bool concurrent, int worker_i);
934 // The shared block offset table array.
935 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
937 // Reference Processing accessor
938 ReferenceProcessor* ref_processor() { return _ref_processor; }
940 virtual size_t capacity() const;
941 virtual size_t used() const;
942 // This should be called when we're not holding the heap lock. The
943 // result might be a bit inaccurate.
944 size_t used_unlocked() const;
945 size_t recalculate_used() const;
946 #ifndef PRODUCT
947 size_t recalculate_used_regions() const;
948 #endif // PRODUCT
950 // These virtual functions do the actual allocation.
951 // Some heaps may offer a contiguous region for shared non-blocking
952 // allocation, via inlined code (by exporting the address of the top and
953 // end fields defining the extent of the contiguous allocation region.)
954 // But G1CollectedHeap doesn't yet support this.
956 // Return an estimate of the maximum allocation that could be performed
957 // without triggering any collection or expansion activity. In a
958 // generational collector, for example, this is probably the largest
959 // allocation that could be supported (without expansion) in the youngest
960 // generation. It is "unsafe" because no locks are taken; the result
961 // should be treated as an approximation, not a guarantee, for use in
962 // heuristic resizing decisions.
963 virtual size_t unsafe_max_alloc();
965 virtual bool is_maximal_no_gc() const {
966 return _g1_storage.uncommitted_size() == 0;
967 }
969 // The total number of regions in the heap.
970 size_t n_regions() { return _hrs.length(); }
972 // The max number of regions in the heap.
973 size_t max_regions() { return _hrs.max_length(); }
975 // The number of regions that are completely free.
976 size_t free_regions() { return _free_list.length(); }
978 // The number of regions that are not completely free.
979 size_t used_regions() { return n_regions() - free_regions(); }
981 // The number of regions available for "regular" expansion.
982 size_t expansion_regions() { return _expansion_regions; }
984 // Factory method for HeapRegion instances. It will return NULL if
985 // the allocation fails.
986 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
988 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
989 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
990 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
991 void verify_dirty_young_regions() PRODUCT_RETURN;
993 // verify_region_sets() performs verification over the region
994 // lists. It will be compiled in the product code to be used when
995 // necessary (i.e., during heap verification).
996 void verify_region_sets();
998 // verify_region_sets_optional() is planted in the code for
999 // list verification in non-product builds (and it can be enabled in
1000 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1001 #if HEAP_REGION_SET_FORCE_VERIFY
1002 void verify_region_sets_optional() {
1003 verify_region_sets();
1004 }
1005 #else // HEAP_REGION_SET_FORCE_VERIFY
1006 void verify_region_sets_optional() { }
1007 #endif // HEAP_REGION_SET_FORCE_VERIFY
1009 #ifdef ASSERT
1010 bool is_on_master_free_list(HeapRegion* hr) {
1011 return hr->containing_set() == &_free_list;
1012 }
1014 bool is_in_humongous_set(HeapRegion* hr) {
1015 return hr->containing_set() == &_humongous_set;
1016 }
1017 #endif // ASSERT
1019 // Wrapper for the region list operations that can be called from
1020 // methods outside this class.
1022 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1023 _secondary_free_list.add_as_tail(list);
1024 }
1026 void append_secondary_free_list() {
1027 _free_list.add_as_head(&_secondary_free_list);
1028 }
1030 void append_secondary_free_list_if_not_empty_with_lock() {
1031 // If the secondary free list looks empty there's no reason to
1032 // take the lock and then try to append it.
1033 if (!_secondary_free_list.is_empty()) {
1034 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1035 append_secondary_free_list();
1036 }
1037 }
1039 void set_free_regions_coming();
1040 void reset_free_regions_coming();
1041 bool free_regions_coming() { return _free_regions_coming; }
1042 void wait_while_free_regions_coming();
1044 // Perform a collection of the heap; intended for use in implementing
1045 // "System.gc". This probably implies as full a collection as the
1046 // "CollectedHeap" supports.
1047 virtual void collect(GCCause::Cause cause);
1049 // The same as above but assume that the caller holds the Heap_lock.
1050 void collect_locked(GCCause::Cause cause);
1052 // This interface assumes that it's being called by the
1053 // vm thread. It collects the heap assuming that the
1054 // heap lock is already held and that we are executing in
1055 // the context of the vm thread.
1056 virtual void collect_as_vm_thread(GCCause::Cause cause);
1058 // True iff a evacuation has failed in the most-recent collection.
1059 bool evacuation_failed() { return _evacuation_failed; }
1061 // It will free a region if it has allocated objects in it that are
1062 // all dead. It calls either free_region() or
1063 // free_humongous_region() depending on the type of the region that
1064 // is passed to it.
1065 void free_region_if_empty(HeapRegion* hr,
1066 size_t* pre_used,
1067 FreeRegionList* free_list,
1068 HumongousRegionSet* humongous_proxy_set,
1069 HRRSCleanupTask* hrrs_cleanup_task,
1070 bool par);
1072 // It appends the free list to the master free list and updates the
1073 // master humongous list according to the contents of the proxy
1074 // list. It also adjusts the total used bytes according to pre_used
1075 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1076 void update_sets_after_freeing_regions(size_t pre_used,
1077 FreeRegionList* free_list,
1078 HumongousRegionSet* humongous_proxy_set,
1079 bool par);
1081 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1082 virtual bool is_in(const void* p) const;
1084 // Return "TRUE" iff the given object address is within the collection
1085 // set.
1086 inline bool obj_in_cs(oop obj);
1088 // Return "TRUE" iff the given object address is in the reserved
1089 // region of g1 (excluding the permanent generation).
1090 bool is_in_g1_reserved(const void* p) const {
1091 return _g1_reserved.contains(p);
1092 }
1094 // Returns a MemRegion that corresponds to the space that has been
1095 // reserved for the heap
1096 MemRegion g1_reserved() {
1097 return _g1_reserved;
1098 }
1100 // Returns a MemRegion that corresponds to the space that has been
1101 // committed in the heap
1102 MemRegion g1_committed() {
1103 return _g1_committed;
1104 }
1106 virtual bool is_in_closed_subset(const void* p) const;
1108 // Dirty card table entries covering a list of young regions.
1109 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1111 // This resets the card table to all zeros. It is used after
1112 // a collection pause which used the card table to claim cards.
1113 void cleanUpCardTable();
1115 // Iteration functions.
1117 // Iterate over all the ref-containing fields of all objects, calling
1118 // "cl.do_oop" on each.
1119 virtual void oop_iterate(OopClosure* cl) {
1120 oop_iterate(cl, true);
1121 }
1122 void oop_iterate(OopClosure* cl, bool do_perm);
1124 // Same as above, restricted to a memory region.
1125 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1126 oop_iterate(mr, cl, true);
1127 }
1128 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1130 // Iterate over all objects, calling "cl.do_object" on each.
1131 virtual void object_iterate(ObjectClosure* cl) {
1132 object_iterate(cl, true);
1133 }
1134 virtual void safe_object_iterate(ObjectClosure* cl) {
1135 object_iterate(cl, true);
1136 }
1137 void object_iterate(ObjectClosure* cl, bool do_perm);
1139 // Iterate over all objects allocated since the last collection, calling
1140 // "cl.do_object" on each. The heap must have been initialized properly
1141 // to support this function, or else this call will fail.
1142 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1144 // Iterate over all spaces in use in the heap, in ascending address order.
1145 virtual void space_iterate(SpaceClosure* cl);
1147 // Iterate over heap regions, in address order, terminating the
1148 // iteration early if the "doHeapRegion" method returns "true".
1149 void heap_region_iterate(HeapRegionClosure* blk) const;
1151 // Iterate over heap regions starting with r (or the first region if "r"
1152 // is NULL), in address order, terminating early if the "doHeapRegion"
1153 // method returns "true".
1154 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1156 // Return the region with the given index. It assumes the index is valid.
1157 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1159 // Divide the heap region sequence into "chunks" of some size (the number
1160 // of regions divided by the number of parallel threads times some
1161 // overpartition factor, currently 4). Assumes that this will be called
1162 // in parallel by ParallelGCThreads worker threads with discinct worker
1163 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1164 // calls will use the same "claim_value", and that that claim value is
1165 // different from the claim_value of any heap region before the start of
1166 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1167 // attempting to claim the first region in each chunk, and, if
1168 // successful, applying the closure to each region in the chunk (and
1169 // setting the claim value of the second and subsequent regions of the
1170 // chunk.) For now requires that "doHeapRegion" always returns "false",
1171 // i.e., that a closure never attempt to abort a traversal.
1172 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1173 int worker,
1174 jint claim_value);
1176 // It resets all the region claim values to the default.
1177 void reset_heap_region_claim_values();
1179 #ifdef ASSERT
1180 bool check_heap_region_claim_values(jint claim_value);
1181 #endif // ASSERT
1183 // Iterate over the regions (if any) in the current collection set.
1184 void collection_set_iterate(HeapRegionClosure* blk);
1186 // As above but starting from region r
1187 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1189 // Returns the first (lowest address) compactible space in the heap.
1190 virtual CompactibleSpace* first_compactible_space();
1192 // A CollectedHeap will contain some number of spaces. This finds the
1193 // space containing a given address, or else returns NULL.
1194 virtual Space* space_containing(const void* addr) const;
1196 // A G1CollectedHeap will contain some number of heap regions. This
1197 // finds the region containing a given address, or else returns NULL.
1198 template <class T>
1199 inline HeapRegion* heap_region_containing(const T addr) const;
1201 // Like the above, but requires "addr" to be in the heap (to avoid a
1202 // null-check), and unlike the above, may return an continuing humongous
1203 // region.
1204 template <class T>
1205 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1207 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1208 // each address in the (reserved) heap is a member of exactly
1209 // one block. The defining characteristic of a block is that it is
1210 // possible to find its size, and thus to progress forward to the next
1211 // block. (Blocks may be of different sizes.) Thus, blocks may
1212 // represent Java objects, or they might be free blocks in a
1213 // free-list-based heap (or subheap), as long as the two kinds are
1214 // distinguishable and the size of each is determinable.
1216 // Returns the address of the start of the "block" that contains the
1217 // address "addr". We say "blocks" instead of "object" since some heaps
1218 // may not pack objects densely; a chunk may either be an object or a
1219 // non-object.
1220 virtual HeapWord* block_start(const void* addr) const;
1222 // Requires "addr" to be the start of a chunk, and returns its size.
1223 // "addr + size" is required to be the start of a new chunk, or the end
1224 // of the active area of the heap.
1225 virtual size_t block_size(const HeapWord* addr) const;
1227 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1228 // the block is an object.
1229 virtual bool block_is_obj(const HeapWord* addr) const;
1231 // Does this heap support heap inspection? (+PrintClassHistogram)
1232 virtual bool supports_heap_inspection() const { return true; }
1234 // Section on thread-local allocation buffers (TLABs)
1235 // See CollectedHeap for semantics.
1237 virtual bool supports_tlab_allocation() const;
1238 virtual size_t tlab_capacity(Thread* thr) const;
1239 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1241 // Can a compiler initialize a new object without store barriers?
1242 // This permission only extends from the creation of a new object
1243 // via a TLAB up to the first subsequent safepoint. If such permission
1244 // is granted for this heap type, the compiler promises to call
1245 // defer_store_barrier() below on any slow path allocation of
1246 // a new object for which such initializing store barriers will
1247 // have been elided. G1, like CMS, allows this, but should be
1248 // ready to provide a compensating write barrier as necessary
1249 // if that storage came out of a non-young region. The efficiency
1250 // of this implementation depends crucially on being able to
1251 // answer very efficiently in constant time whether a piece of
1252 // storage in the heap comes from a young region or not.
1253 // See ReduceInitialCardMarks.
1254 virtual bool can_elide_tlab_store_barriers() const {
1255 // 6920090: Temporarily disabled, because of lingering
1256 // instabilities related to RICM with G1. In the
1257 // interim, the option ReduceInitialCardMarksForG1
1258 // below is left solely as a debugging device at least
1259 // until 6920109 fixes the instabilities.
1260 return ReduceInitialCardMarksForG1;
1261 }
1263 virtual bool card_mark_must_follow_store() const {
1264 return true;
1265 }
1267 bool is_in_young(const oop obj) {
1268 HeapRegion* hr = heap_region_containing(obj);
1269 return hr != NULL && hr->is_young();
1270 }
1272 #ifdef ASSERT
1273 virtual bool is_in_partial_collection(const void* p);
1274 #endif
1276 virtual bool is_scavengable(const void* addr);
1278 // We don't need barriers for initializing stores to objects
1279 // in the young gen: for the SATB pre-barrier, there is no
1280 // pre-value that needs to be remembered; for the remembered-set
1281 // update logging post-barrier, we don't maintain remembered set
1282 // information for young gen objects. Note that non-generational
1283 // G1 does not have any "young" objects, should not elide
1284 // the rs logging barrier and so should always answer false below.
1285 // However, non-generational G1 (-XX:-G1Gen) appears to have
1286 // bit-rotted so was not tested below.
1287 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1288 // Re 6920090, 6920109 above.
1289 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1290 assert(G1Gen || !is_in_young(new_obj),
1291 "Non-generational G1 should never return true below");
1292 return is_in_young(new_obj);
1293 }
1295 // Can a compiler elide a store barrier when it writes
1296 // a permanent oop into the heap? Applies when the compiler
1297 // is storing x to the heap, where x->is_perm() is true.
1298 virtual bool can_elide_permanent_oop_store_barriers() const {
1299 // At least until perm gen collection is also G1-ified, at
1300 // which point this should return false.
1301 return true;
1302 }
1304 // Returns "true" iff the given word_size is "very large".
1305 static bool isHumongous(size_t word_size) {
1306 // Note this has to be strictly greater-than as the TLABs
1307 // are capped at the humongous thresold and we want to
1308 // ensure that we don't try to allocate a TLAB as
1309 // humongous and that we don't allocate a humongous
1310 // object in a TLAB.
1311 return word_size > _humongous_object_threshold_in_words;
1312 }
1314 // Update mod union table with the set of dirty cards.
1315 void updateModUnion();
1317 // Set the mod union bits corresponding to the given memRegion. Note
1318 // that this is always a safe operation, since it doesn't clear any
1319 // bits.
1320 void markModUnionRange(MemRegion mr);
1322 // Records the fact that a marking phase is no longer in progress.
1323 void set_marking_complete() {
1324 _mark_in_progress = false;
1325 }
1326 void set_marking_started() {
1327 _mark_in_progress = true;
1328 }
1329 bool mark_in_progress() {
1330 return _mark_in_progress;
1331 }
1333 // Print the maximum heap capacity.
1334 virtual size_t max_capacity() const;
1336 virtual jlong millis_since_last_gc();
1338 // Perform any cleanup actions necessary before allowing a verification.
1339 virtual void prepare_for_verify();
1341 // Perform verification.
1343 // vo == UsePrevMarking -> use "prev" marking information,
1344 // vo == UseNextMarking -> use "next" marking information
1345 // vo == UseMarkWord -> use the mark word in the object header
1346 //
1347 // NOTE: Only the "prev" marking information is guaranteed to be
1348 // consistent most of the time, so most calls to this should use
1349 // vo == UsePrevMarking.
1350 // Currently, there is only one case where this is called with
1351 // vo == UseNextMarking, which is to verify the "next" marking
1352 // information at the end of remark.
1353 // Currently there is only one place where this is called with
1354 // vo == UseMarkWord, which is to verify the marking during a
1355 // full GC.
1356 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1358 // Override; it uses the "prev" marking information
1359 virtual void verify(bool allow_dirty, bool silent);
1360 // Default behavior by calling print(tty);
1361 virtual void print() const;
1362 // This calls print_on(st, PrintHeapAtGCExtended).
1363 virtual void print_on(outputStream* st) const;
1364 // If extended is true, it will print out information for all
1365 // regions in the heap by calling print_on_extended(st).
1366 virtual void print_on(outputStream* st, bool extended) const;
1367 virtual void print_on_extended(outputStream* st) const;
1369 virtual void print_gc_threads_on(outputStream* st) const;
1370 virtual void gc_threads_do(ThreadClosure* tc) const;
1372 // Override
1373 void print_tracing_info() const;
1375 // Convenience function to be used in situations where the heap type can be
1376 // asserted to be this type.
1377 static G1CollectedHeap* heap();
1379 void empty_young_list();
1381 void set_region_short_lived_locked(HeapRegion* hr);
1382 // add appropriate methods for any other surv rate groups
1384 YoungList* young_list() { return _young_list; }
1386 // debugging
1387 bool check_young_list_well_formed() {
1388 return _young_list->check_list_well_formed();
1389 }
1391 bool check_young_list_empty(bool check_heap,
1392 bool check_sample = true);
1394 // *** Stuff related to concurrent marking. It's not clear to me that so
1395 // many of these need to be public.
1397 // The functions below are helper functions that a subclass of
1398 // "CollectedHeap" can use in the implementation of its virtual
1399 // functions.
1400 // This performs a concurrent marking of the live objects in a
1401 // bitmap off to the side.
1402 void doConcurrentMark();
1404 // Do a full concurrent marking, synchronously.
1405 void do_sync_mark();
1407 bool isMarkedPrev(oop obj) const;
1408 bool isMarkedNext(oop obj) const;
1410 // vo == UsePrevMarking -> use "prev" marking information,
1411 // vo == UseNextMarking -> use "next" marking information,
1412 // vo == UseMarkWord -> use mark word from object header
1413 bool is_obj_dead_cond(const oop obj,
1414 const HeapRegion* hr,
1415 const VerifyOption vo) const {
1417 switch (vo) {
1418 case VerifyOption_G1UsePrevMarking:
1419 return is_obj_dead(obj, hr);
1420 case VerifyOption_G1UseNextMarking:
1421 return is_obj_ill(obj, hr);
1422 default:
1423 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1424 return !obj->is_gc_marked();
1425 }
1426 }
1428 // Determine if an object is dead, given the object and also
1429 // the region to which the object belongs. An object is dead
1430 // iff a) it was not allocated since the last mark and b) it
1431 // is not marked.
1433 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1434 return
1435 !hr->obj_allocated_since_prev_marking(obj) &&
1436 !isMarkedPrev(obj);
1437 }
1439 // This is used when copying an object to survivor space.
1440 // If the object is marked live, then we mark the copy live.
1441 // If the object is allocated since the start of this mark
1442 // cycle, then we mark the copy live.
1443 // If the object has been around since the previous mark
1444 // phase, and hasn't been marked yet during this phase,
1445 // then we don't mark it, we just wait for the
1446 // current marking cycle to get to it.
1448 // This function returns true when an object has been
1449 // around since the previous marking and hasn't yet
1450 // been marked during this marking.
1452 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1453 return
1454 !hr->obj_allocated_since_next_marking(obj) &&
1455 !isMarkedNext(obj);
1456 }
1458 // Determine if an object is dead, given only the object itself.
1459 // This will find the region to which the object belongs and
1460 // then call the region version of the same function.
1462 // Added if it is in permanent gen it isn't dead.
1463 // Added if it is NULL it isn't dead.
1465 // vo == UsePrevMarking -> use "prev" marking information,
1466 // vo == UseNextMarking -> use "next" marking information,
1467 // vo == UseMarkWord -> use mark word from object header
1468 bool is_obj_dead_cond(const oop obj,
1469 const VerifyOption vo) const {
1471 switch (vo) {
1472 case VerifyOption_G1UsePrevMarking:
1473 return is_obj_dead(obj);
1474 case VerifyOption_G1UseNextMarking:
1475 return is_obj_ill(obj);
1476 default:
1477 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1478 return !obj->is_gc_marked();
1479 }
1480 }
1482 bool is_obj_dead(const oop obj) const {
1483 const HeapRegion* hr = heap_region_containing(obj);
1484 if (hr == NULL) {
1485 if (Universe::heap()->is_in_permanent(obj))
1486 return false;
1487 else if (obj == NULL) return false;
1488 else return true;
1489 }
1490 else return is_obj_dead(obj, hr);
1491 }
1493 bool is_obj_ill(const oop obj) const {
1494 const HeapRegion* hr = heap_region_containing(obj);
1495 if (hr == NULL) {
1496 if (Universe::heap()->is_in_permanent(obj))
1497 return false;
1498 else if (obj == NULL) return false;
1499 else return true;
1500 }
1501 else return is_obj_ill(obj, hr);
1502 }
1504 // The following is just to alert the verification code
1505 // that a full collection has occurred and that the
1506 // remembered sets are no longer up to date.
1507 bool _full_collection;
1508 void set_full_collection() { _full_collection = true;}
1509 void clear_full_collection() {_full_collection = false;}
1510 bool full_collection() {return _full_collection;}
1512 ConcurrentMark* concurrent_mark() const { return _cm; }
1513 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
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();
1525 public:
1526 void stop_conc_gc_threads();
1528 // <NEW PREDICTION>
1530 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1531 void check_if_region_is_too_expensive(double predicted_time_ms);
1532 size_t pending_card_num();
1533 size_t max_pending_card_num();
1534 size_t cards_scanned();
1536 // </NEW PREDICTION>
1538 protected:
1539 size_t _max_heap_capacity;
1540 };
1542 #define use_local_bitmaps 1
1543 #define verify_local_bitmaps 0
1544 #define oop_buffer_length 256
1546 #ifndef PRODUCT
1547 class GCLabBitMap;
1548 class GCLabBitMapClosure: public BitMapClosure {
1549 private:
1550 ConcurrentMark* _cm;
1551 GCLabBitMap* _bitmap;
1553 public:
1554 GCLabBitMapClosure(ConcurrentMark* cm,
1555 GCLabBitMap* bitmap) {
1556 _cm = cm;
1557 _bitmap = bitmap;
1558 }
1560 virtual bool do_bit(size_t offset);
1561 };
1562 #endif // !PRODUCT
1564 class GCLabBitMap: public BitMap {
1565 private:
1566 ConcurrentMark* _cm;
1568 int _shifter;
1569 size_t _bitmap_word_covers_words;
1571 // beginning of the heap
1572 HeapWord* _heap_start;
1574 // this is the actual start of the GCLab
1575 HeapWord* _real_start_word;
1577 // this is the actual end of the GCLab
1578 HeapWord* _real_end_word;
1580 // this is the first word, possibly located before the actual start
1581 // of the GCLab, that corresponds to the first bit of the bitmap
1582 HeapWord* _start_word;
1584 // size of a GCLab in words
1585 size_t _gclab_word_size;
1587 static int shifter() {
1588 return MinObjAlignment - 1;
1589 }
1591 // how many heap words does a single bitmap word corresponds to?
1592 static size_t bitmap_word_covers_words() {
1593 return BitsPerWord << shifter();
1594 }
1596 size_t gclab_word_size() const {
1597 return _gclab_word_size;
1598 }
1600 // Calculates actual GCLab size in words
1601 size_t gclab_real_word_size() const {
1602 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1603 / BitsPerWord;
1604 }
1606 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1607 size_t bits_in_bitmap = gclab_word_size >> shifter();
1608 // We are going to ensure that the beginning of a word in this
1609 // bitmap also corresponds to the beginning of a word in the
1610 // global marking bitmap. To handle the case where a GCLab
1611 // starts from the middle of the bitmap, we need to add enough
1612 // space (i.e. up to a bitmap word) to ensure that we have
1613 // enough bits in the bitmap.
1614 return bits_in_bitmap + BitsPerWord - 1;
1615 }
1616 public:
1617 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1618 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1619 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1620 _shifter(shifter()),
1621 _bitmap_word_covers_words(bitmap_word_covers_words()),
1622 _heap_start(heap_start),
1623 _gclab_word_size(gclab_word_size),
1624 _real_start_word(NULL),
1625 _real_end_word(NULL),
1626 _start_word(NULL)
1627 {
1628 guarantee( size_in_words() >= bitmap_size_in_words(),
1629 "just making sure");
1630 }
1632 inline unsigned heapWordToOffset(HeapWord* addr) {
1633 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1634 assert(offset < size(), "offset should be within bounds");
1635 return offset;
1636 }
1638 inline HeapWord* offsetToHeapWord(size_t offset) {
1639 HeapWord* addr = _start_word + (offset << _shifter);
1640 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1641 return addr;
1642 }
1644 bool fields_well_formed() {
1645 bool ret1 = (_real_start_word == NULL) &&
1646 (_real_end_word == NULL) &&
1647 (_start_word == NULL);
1648 if (ret1)
1649 return true;
1651 bool ret2 = _real_start_word >= _start_word &&
1652 _start_word < _real_end_word &&
1653 (_real_start_word + _gclab_word_size) == _real_end_word &&
1654 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1655 > _real_end_word;
1656 return ret2;
1657 }
1659 inline bool mark(HeapWord* addr) {
1660 guarantee(use_local_bitmaps, "invariant");
1661 assert(fields_well_formed(), "invariant");
1663 if (addr >= _real_start_word && addr < _real_end_word) {
1664 assert(!isMarked(addr), "should not have already been marked");
1666 // first mark it on the bitmap
1667 at_put(heapWordToOffset(addr), true);
1669 return true;
1670 } else {
1671 return false;
1672 }
1673 }
1675 inline bool isMarked(HeapWord* addr) {
1676 guarantee(use_local_bitmaps, "invariant");
1677 assert(fields_well_formed(), "invariant");
1679 return at(heapWordToOffset(addr));
1680 }
1682 void set_buffer(HeapWord* start) {
1683 guarantee(use_local_bitmaps, "invariant");
1684 clear();
1686 assert(start != NULL, "invariant");
1687 _real_start_word = start;
1688 _real_end_word = start + _gclab_word_size;
1690 size_t diff =
1691 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1692 _start_word = start - diff;
1694 assert(fields_well_formed(), "invariant");
1695 }
1697 #ifndef PRODUCT
1698 void verify() {
1699 // verify that the marks have been propagated
1700 GCLabBitMapClosure cl(_cm, this);
1701 iterate(&cl);
1702 }
1703 #endif // PRODUCT
1705 void retire() {
1706 guarantee(use_local_bitmaps, "invariant");
1707 assert(fields_well_formed(), "invariant");
1709 if (_start_word != NULL) {
1710 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1712 // this means that the bitmap was set up for the GCLab
1713 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1715 mark_bitmap->mostly_disjoint_range_union(this,
1716 0, // always start from the start of the bitmap
1717 _start_word,
1718 gclab_real_word_size());
1719 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1721 #ifndef PRODUCT
1722 if (use_local_bitmaps && verify_local_bitmaps)
1723 verify();
1724 #endif // PRODUCT
1725 } else {
1726 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1727 }
1728 }
1730 size_t bitmap_size_in_words() const {
1731 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1732 }
1734 };
1736 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1737 private:
1738 bool _retired;
1739 bool _during_marking;
1740 GCLabBitMap _bitmap;
1742 public:
1743 G1ParGCAllocBuffer(size_t gclab_word_size) :
1744 ParGCAllocBuffer(gclab_word_size),
1745 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1746 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1747 _retired(false)
1748 { }
1750 inline bool mark(HeapWord* addr) {
1751 guarantee(use_local_bitmaps, "invariant");
1752 assert(_during_marking, "invariant");
1753 return _bitmap.mark(addr);
1754 }
1756 inline void set_buf(HeapWord* buf) {
1757 if (use_local_bitmaps && _during_marking)
1758 _bitmap.set_buffer(buf);
1759 ParGCAllocBuffer::set_buf(buf);
1760 _retired = false;
1761 }
1763 inline void retire(bool end_of_gc, bool retain) {
1764 if (_retired)
1765 return;
1766 if (use_local_bitmaps && _during_marking) {
1767 _bitmap.retire();
1768 }
1769 ParGCAllocBuffer::retire(end_of_gc, retain);
1770 _retired = true;
1771 }
1772 };
1774 class G1ParScanThreadState : public StackObj {
1775 protected:
1776 G1CollectedHeap* _g1h;
1777 RefToScanQueue* _refs;
1778 DirtyCardQueue _dcq;
1779 CardTableModRefBS* _ct_bs;
1780 G1RemSet* _g1_rem;
1782 G1ParGCAllocBuffer _surviving_alloc_buffer;
1783 G1ParGCAllocBuffer _tenured_alloc_buffer;
1784 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1785 ageTable _age_table;
1787 size_t _alloc_buffer_waste;
1788 size_t _undo_waste;
1790 OopsInHeapRegionClosure* _evac_failure_cl;
1791 G1ParScanHeapEvacClosure* _evac_cl;
1792 G1ParScanPartialArrayClosure* _partial_scan_cl;
1794 int _hash_seed;
1795 int _queue_num;
1797 size_t _term_attempts;
1799 double _start;
1800 double _start_strong_roots;
1801 double _strong_roots_time;
1802 double _start_term;
1803 double _term_time;
1805 // Map from young-age-index (0 == not young, 1 is youngest) to
1806 // surviving words. base is what we get back from the malloc call
1807 size_t* _surviving_young_words_base;
1808 // this points into the array, as we use the first few entries for padding
1809 size_t* _surviving_young_words;
1811 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1813 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1815 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1817 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1818 CardTableModRefBS* ctbs() { return _ct_bs; }
1820 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1821 if (!from->is_survivor()) {
1822 _g1_rem->par_write_ref(from, p, tid);
1823 }
1824 }
1826 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1827 // If the new value of the field points to the same region or
1828 // is the to-space, we don't need to include it in the Rset updates.
1829 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1830 size_t card_index = ctbs()->index_for(p);
1831 // If the card hasn't been added to the buffer, do it.
1832 if (ctbs()->mark_card_deferred(card_index)) {
1833 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1834 }
1835 }
1836 }
1838 public:
1839 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1841 ~G1ParScanThreadState() {
1842 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1843 }
1845 RefToScanQueue* refs() { return _refs; }
1846 ageTable* age_table() { return &_age_table; }
1848 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1849 return _alloc_buffers[purpose];
1850 }
1852 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1853 size_t undo_waste() const { return _undo_waste; }
1855 #ifdef ASSERT
1856 bool verify_ref(narrowOop* ref) const;
1857 bool verify_ref(oop* ref) const;
1858 bool verify_task(StarTask ref) const;
1859 #endif // ASSERT
1861 template <class T> void push_on_queue(T* ref) {
1862 assert(verify_ref(ref), "sanity");
1863 refs()->push(ref);
1864 }
1866 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1867 if (G1DeferredRSUpdate) {
1868 deferred_rs_update(from, p, tid);
1869 } else {
1870 immediate_rs_update(from, p, tid);
1871 }
1872 }
1874 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1876 HeapWord* obj = NULL;
1877 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1878 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1879 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1880 assert(gclab_word_size == alloc_buf->word_sz(),
1881 "dynamic resizing is not supported");
1882 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1883 alloc_buf->retire(false, false);
1885 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1886 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1887 // Otherwise.
1888 alloc_buf->set_buf(buf);
1890 obj = alloc_buf->allocate(word_sz);
1891 assert(obj != NULL, "buffer was definitely big enough...");
1892 } else {
1893 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1894 }
1895 return obj;
1896 }
1898 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1899 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1900 if (obj != NULL) return obj;
1901 return allocate_slow(purpose, word_sz);
1902 }
1904 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1905 if (alloc_buffer(purpose)->contains(obj)) {
1906 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1907 "should contain whole object");
1908 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1909 } else {
1910 CollectedHeap::fill_with_object(obj, word_sz);
1911 add_to_undo_waste(word_sz);
1912 }
1913 }
1915 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1916 _evac_failure_cl = evac_failure_cl;
1917 }
1918 OopsInHeapRegionClosure* evac_failure_closure() {
1919 return _evac_failure_cl;
1920 }
1922 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1923 _evac_cl = evac_cl;
1924 }
1926 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1927 _partial_scan_cl = partial_scan_cl;
1928 }
1930 int* hash_seed() { return &_hash_seed; }
1931 int queue_num() { return _queue_num; }
1933 size_t term_attempts() const { return _term_attempts; }
1934 void note_term_attempt() { _term_attempts++; }
1936 void start_strong_roots() {
1937 _start_strong_roots = os::elapsedTime();
1938 }
1939 void end_strong_roots() {
1940 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1941 }
1942 double strong_roots_time() const { return _strong_roots_time; }
1944 void start_term_time() {
1945 note_term_attempt();
1946 _start_term = os::elapsedTime();
1947 }
1948 void end_term_time() {
1949 _term_time += (os::elapsedTime() - _start_term);
1950 }
1951 double term_time() const { return _term_time; }
1953 double elapsed_time() const {
1954 return os::elapsedTime() - _start;
1955 }
1957 static void
1958 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1959 void
1960 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1962 size_t* surviving_young_words() {
1963 // We add on to hide entry 0 which accumulates surviving words for
1964 // age -1 regions (i.e. non-young ones)
1965 return _surviving_young_words;
1966 }
1968 void retire_alloc_buffers() {
1969 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1970 size_t waste = _alloc_buffers[ap]->words_remaining();
1971 add_to_alloc_buffer_waste(waste);
1972 _alloc_buffers[ap]->retire(true, false);
1973 }
1974 }
1976 template <class T> void deal_with_reference(T* ref_to_scan) {
1977 if (has_partial_array_mask(ref_to_scan)) {
1978 _partial_scan_cl->do_oop_nv(ref_to_scan);
1979 } else {
1980 // Note: we can use "raw" versions of "region_containing" because
1981 // "obj_to_scan" is definitely in the heap, and is not in a
1982 // humongous region.
1983 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1984 _evac_cl->set_region(r);
1985 _evac_cl->do_oop_nv(ref_to_scan);
1986 }
1987 }
1989 void deal_with_reference(StarTask ref) {
1990 assert(verify_task(ref), "sanity");
1991 if (ref.is_narrow()) {
1992 deal_with_reference((narrowOop*)ref);
1993 } else {
1994 deal_with_reference((oop*)ref);
1995 }
1996 }
1998 public:
1999 void trim_queue();
2000 };
2002 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP