1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_VM_MEMORY_GENERATION_HPP
26 #define SHARE_VM_MEMORY_GENERATION_HPP
27
28 #include "gc_implementation/shared/collectorCounters.hpp"
29 #include "gc_implementation/shared/gcTrace.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/memRegion.hpp"
32 #include "memory/referenceProcessor.hpp"
33 #include "memory/universe.hpp"
34 #include "memory/watermark.hpp"
35 #include "runtime/mutex.hpp"
36 #include "runtime/perfData.hpp"
37 #include "runtime/virtualspace.hpp"
38
39 // A Generation models a heap area for similarly-aged objects.
40 // It will contain one ore more spaces holding the actual objects.
41 //
42 // The Generation class hierarchy:
43 //
44 // Generation - abstract base class
45 // - DefNewGeneration - allocation area (copy collected)
46 // - ParNewGeneration - a DefNewGeneration that is collected by
47 // several threads
48 // - CardGeneration - abstract class adding offset array behavior
49 // - OneContigSpaceCardGeneration - abstract class holding a single
50 // contiguous space with card marking
51 // - TenuredGeneration - tenured (old object) space (markSweepCompact)
52 // - ConcurrentMarkSweepGeneration - Mostly Concurrent Mark Sweep Generation
53 // (Detlefs-Printezis refinement of
54 // Boehm-Demers-Schenker)
55 //
56 // The system configurations currently allowed are:
57 //
58 // DefNewGeneration + TenuredGeneration
59 // DefNewGeneration + ConcurrentMarkSweepGeneration
60 //
61 // ParNewGeneration + TenuredGeneration
62 // ParNewGeneration + ConcurrentMarkSweepGeneration
63 //
64
65 class DefNewGeneration;
66 class GenerationSpec;
67 class CompactibleSpace;
68 class ContiguousSpace;
69 class CompactPoint;
70 class OopsInGenClosure;
71 class OopClosure;
72 class ScanClosure;
73 class FastScanClosure;
74 class GenCollectedHeap;
75 class GenRemSet;
76 class GCStats;
77
78 // A "ScratchBlock" represents a block of memory in one generation usable by
79 // another. It represents "num_words" free words, starting at and including
80 // the address of "this".
81 struct ScratchBlock {
82 ScratchBlock* next;
83 size_t num_words;
84 HeapWord scratch_space[1]; // Actually, of size "num_words-2" (assuming
85 // first two fields are word-sized.)
86 };
87
88
89 class Generation: public CHeapObj<mtGC> {
90 friend class VMStructs;
91 private:
92 jlong _time_of_last_gc; // time when last gc on this generation happened (ms)
93 MemRegion _prev_used_region; // for collectors that want to "remember" a value for
94 // used region at some specific point during collection.
95
96 protected:
97 // Minimum and maximum addresses for memory reserved (not necessarily
98 // committed) for generation.
99 // Used by card marking code. Must not overlap with address ranges of
100 // other generations.
101 MemRegion _reserved;
102
103 // Memory area reserved for generation
104 VirtualSpace _virtual_space;
105
106 // Level in the generation hierarchy.
107 int _level;
108
109 // ("Weak") Reference processing support
110 ReferenceProcessor* _ref_processor;
111
112 // Performance Counters
113 CollectorCounters* _gc_counters;
114
115 // Statistics for garbage collection
116 GCStats* _gc_stats;
117
118 // Returns the next generation in the configuration, or else NULL if this
119 // is the highest generation.
120 Generation* next_gen() const;
121
122 // Initialize the generation.
123 Generation(ReservedSpace rs, size_t initial_byte_size, int level);
124
125 // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in
126 // "sp" that point into younger generations.
127 // The iteration is only over objects allocated at the start of the
128 // iterations; objects allocated as a result of applying the closure are
129 // not included.
130 void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
131
132 public:
133 // The set of possible generation kinds.
134 enum Name {
135 DefNew,
136 ParNew,
137 MarkSweepCompact,
138 ConcurrentMarkSweep,
139 Other
140 };
141
142 enum SomePublicConstants {
143 // Generations are GenGrain-aligned and have size that are multiples of
144 // GenGrain.
145 // Note: on ARM we add 1 bit for card_table_base to be properly aligned
146 // (we expect its low byte to be zero - see implementation of post_barrier)
147 LogOfGenGrain = 16 ARM_ONLY(+1),
148 GenGrain = 1 << LogOfGenGrain
149 };
150
151 // allocate and initialize ("weak") refs processing support
152 virtual void ref_processor_init();
153 void set_ref_processor(ReferenceProcessor* rp) {
154 assert(_ref_processor == NULL, "clobbering existing _ref_processor");
155 _ref_processor = rp;
156 }
157
158 virtual Generation::Name kind() { return Generation::Other; }
159 GenerationSpec* spec();
160
161 // This properly belongs in the collector, but for now this
162 // will do.
163 virtual bool refs_discovery_is_atomic() const { return true; }
164 virtual bool refs_discovery_is_mt() const { return false; }
165
166 // Space enquiries (results in bytes)
167 virtual size_t capacity() const = 0; // The maximum number of object bytes the
168 // generation can currently hold.
169 virtual size_t used() const = 0; // The number of used bytes in the gen.
170 virtual size_t free() const = 0; // The number of free bytes in the gen.
171
172 // Support for java.lang.Runtime.maxMemory(); see CollectedHeap.
173 // Returns the total number of bytes available in a generation
174 // for the allocation of objects.
175 virtual size_t max_capacity() const;
176
177 // If this is a young generation, the maximum number of bytes that can be
178 // allocated in this generation before a GC is triggered.
179 virtual size_t capacity_before_gc() const { return 0; }
180
181 // The largest number of contiguous free bytes in the generation,
182 // including expansion (Assumes called at a safepoint.)
183 virtual size_t contiguous_available() const = 0;
184 // The largest number of contiguous free bytes in this or any higher generation.
185 virtual size_t max_contiguous_available() const;
186
187 // Returns true if promotions of the specified amount are
188 // likely to succeed without a promotion failure.
189 // Promotion of the full amount is not guaranteed but
190 // might be attempted in the worst case.
191 virtual bool promotion_attempt_is_safe(size_t max_promotion_in_bytes) const;
192
193 // For a non-young generation, this interface can be used to inform a
194 // generation that a promotion attempt into that generation failed.
195 // Typically used to enable diagnostic output for post-mortem analysis,
196 // but other uses of the interface are not ruled out.
197 virtual void promotion_failure_occurred() { /* does nothing */ }
198
199 // Return an estimate of the maximum allocation that could be performed
200 // in the generation without triggering any collection or expansion
201 // activity. It is "unsafe" because no locks are taken; the result
202 // should be treated as an approximation, not a guarantee, for use in
203 // heuristic resizing decisions.
204 virtual size_t unsafe_max_alloc_nogc() const = 0;
205
206 // Returns true if this generation cannot be expanded further
207 // without a GC. Override as appropriate.
208 virtual bool is_maximal_no_gc() const {
209 return _virtual_space.uncommitted_size() == 0;
210 }
211
212 MemRegion reserved() const { return _reserved; }
213
214 // Returns a region guaranteed to contain all the objects in the
215 // generation.
216 virtual MemRegion used_region() const { return _reserved; }
217
218 MemRegion prev_used_region() const { return _prev_used_region; }
219 virtual void save_used_region() { _prev_used_region = used_region(); }
220
221 // Returns "TRUE" iff "p" points into the committed areas in the generation.
222 // For some kinds of generations, this may be an expensive operation.
223 // To avoid performance problems stemming from its inadvertent use in
224 // product jvm's, we restrict its use to assertion checking or
225 // verification only.
226 virtual bool is_in(const void* p) const;
227
228 /* Returns "TRUE" iff "p" points into the reserved area of the generation. */
229 bool is_in_reserved(const void* p) const {
230 return _reserved.contains(p);
231 }
232
233 // Check that the generation kind is DefNewGeneration or a sub
234 // class of DefNewGeneration and return a DefNewGeneration*
235 DefNewGeneration* as_DefNewGeneration();
236
237 // If some space in the generation contains the given "addr", return a
238 // pointer to that space, else return "NULL".
239 virtual Space* space_containing(const void* addr) const;
240
241 // Iteration - do not use for time critical operations
242 virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0;
243
244 // Returns the first space, if any, in the generation that can participate
245 // in compaction, or else "NULL".
246 virtual CompactibleSpace* first_compaction_space() const = 0;
247
248 // Returns "true" iff this generation should be used to allocate an
249 // object of the given size. Young generations might
250 // wish to exclude very large objects, for example, since, if allocated
251 // often, they would greatly increase the frequency of young-gen
252 // collection.
253 virtual bool should_allocate(size_t word_size, bool is_tlab) {
254 bool result = false;
255 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
256 if (!is_tlab || supports_tlab_allocation()) {
257 result = (word_size > 0) && (word_size < overflow_limit);
258 }
259 return result;
260 }
261
262 // Allocate and returns a block of the requested size, or returns "NULL".
263 // Assumes the caller has done any necessary locking.
264 virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0;
265
266 // Like "allocate", but performs any necessary locking internally.
267 virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0;
268
269 // Some generation may offer a region for shared, contiguous allocation,
270 // via inlined code (by exporting the address of the top and end fields
271 // defining the extent of the contiguous allocation region.)
272
273 // This function returns "true" iff the heap supports this kind of
274 // allocation. (More precisely, this means the style of allocation that
275 // increments *top_addr()" with a CAS.) (Default is "no".)
276 // A generation that supports this allocation style must use lock-free
277 // allocation for *all* allocation, since there are times when lock free
278 // allocation will be concurrent with plain "allocate" calls.
279 virtual bool supports_inline_contig_alloc() const { return false; }
280
281 // These functions return the addresses of the fields that define the
282 // boundaries of the contiguous allocation area. (These fields should be
283 // physically near to one another.)
284 virtual HeapWord** top_addr() const { return NULL; }
285 virtual HeapWord** end_addr() const { return NULL; }
286
287 // Thread-local allocation buffers
288 virtual bool supports_tlab_allocation() const { return false; }
289 virtual size_t tlab_capacity() const {
290 guarantee(false, "Generation doesn't support thread local allocation buffers");
291 return 0;
292 }
293 virtual size_t tlab_used() const {
294 guarantee(false, "Generation doesn't support thread local allocation buffers");
295 return 0;
296 }
297 virtual size_t unsafe_max_tlab_alloc() const {
298 guarantee(false, "Generation doesn't support thread local allocation buffers");
299 return 0;
300 }
301
302 // "obj" is the address of an object in a younger generation. Allocate space
303 // for "obj" in the current (or some higher) generation, and copy "obj" into
304 // the newly allocated space, if possible, returning the result (or NULL if
305 // the allocation failed).
306 //
307 // The "obj_size" argument is just obj->size(), passed along so the caller can
308 // avoid repeating the virtual call to retrieve it.
309 virtual oop promote(oop obj, size_t obj_size);
310
311 // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote
312 // object "obj", whose original mark word was "m", and whose size is
313 // "word_sz". If possible, allocate space for "obj", copy obj into it
314 // (taking care to copy "m" into the mark word when done, since the mark
315 // word of "obj" may have been overwritten with a forwarding pointer, and
316 // also taking care to copy the klass pointer *last*. Returns the new
317 // object if successful, or else NULL.
318 virtual oop par_promote(const ParNewTracer* _gc_tracer, int thread_num,
319 oop obj, markOop m, size_t word_sz);
320
321 // Undo, if possible, the most recent par_promote_alloc allocation by
322 // "thread_num" ("obj", of "word_sz").
323 virtual void par_promote_alloc_undo(int thread_num,
324 HeapWord* obj, size_t word_sz);
325
326 // Informs the current generation that all par_promote_alloc's in the
327 // collection have been completed; any supporting data structures can be
328 // reset. Default is to do nothing.
329 virtual void par_promote_alloc_done(int thread_num) {}
330
331 // Informs the current generation that all oop_since_save_marks_iterates
332 // performed by "thread_num" in the current collection, if any, have been
333 // completed; any supporting data structures can be reset. Default is to
334 // do nothing.
335 virtual void par_oop_since_save_marks_iterate_done(int thread_num) {}
336
337 // This generation will collect all younger generations
338 // during a full collection.
339 virtual bool full_collects_younger_generations() const { return false; }
340
341 // This generation does in-place marking, meaning that mark words
342 // are mutated during the marking phase and presumably reinitialized
343 // to a canonical value after the GC. This is currently used by the
344 // biased locking implementation to determine whether additional
345 // work is required during the GC prologue and epilogue.
346 virtual bool performs_in_place_marking() const { return true; }
347
348 // Returns "true" iff collect() should subsequently be called on this
349 // this generation. See comment below.
350 // This is a generic implementation which can be overridden.
351 //
352 // Note: in the current (1.4) implementation, when genCollectedHeap's
353 // incremental_collection_will_fail flag is set, all allocations are
354 // slow path (the only fast-path place to allocate is DefNew, which
355 // will be full if the flag is set).
356 // Thus, older generations which collect younger generations should
357 // test this flag and collect if it is set.
358 virtual bool should_collect(bool full,
359 size_t word_size,
360 bool is_tlab) {
361 return (full || should_allocate(word_size, is_tlab));
362 }
363
364 // Returns true if the collection is likely to be safely
365 // completed. Even if this method returns true, a collection
366 // may not be guaranteed to succeed, and the system should be
367 // able to safely unwind and recover from that failure, albeit
368 // at some additional cost.
369 virtual bool collection_attempt_is_safe() {
370 guarantee(false, "Are you sure you want to call this method?");
371 return true;
372 }
373
374 // Perform a garbage collection.
375 // If full is true attempt a full garbage collection of this generation.
376 // Otherwise, attempting to (at least) free enough space to support an
377 // allocation of the given "word_size".
378 virtual void collect(bool full,
379 bool clear_all_soft_refs,
380 size_t word_size,
381 bool is_tlab) = 0;
382
383 // Perform a heap collection, attempting to create (at least) enough
384 // space to support an allocation of the given "word_size". If
385 // successful, perform the allocation and return the resulting
386 // "oop" (initializing the allocated block). If the allocation is
387 // still unsuccessful, return "NULL".
388 virtual HeapWord* expand_and_allocate(size_t word_size,
389 bool is_tlab,
390 bool parallel = false) = 0;
391
392 // Some generations may require some cleanup or preparation actions before
393 // allowing a collection. The default is to do nothing.
394 virtual void gc_prologue(bool full) {};
395
396 // Some generations may require some cleanup actions after a collection.
397 // The default is to do nothing.
398 virtual void gc_epilogue(bool full) {};
399
400 // Save the high water marks for the used space in a generation.
401 virtual void record_spaces_top() {};
402
403 // Some generations may need to be "fixed-up" after some allocation
404 // activity to make them parsable again. The default is to do nothing.
405 virtual void ensure_parsability() {};
406
407 // Time (in ms) when we were last collected or now if a collection is
408 // in progress.
409 virtual jlong time_of_last_gc(jlong now) {
410 // Both _time_of_last_gc and now are set using a time source
411 // that guarantees monotonically non-decreasing values provided
412 // the underlying platform provides such a source. So we still
413 // have to guard against non-monotonicity.
414 NOT_PRODUCT(
415 if (now < _time_of_last_gc) {
416 warning("time warp: "INT64_FORMAT" to "INT64_FORMAT, (int64_t)_time_of_last_gc, (int64_t)now);
417 }
418 )
419 return _time_of_last_gc;
420 }
421
422 virtual void update_time_of_last_gc(jlong now) {
423 _time_of_last_gc = now;
424 }
425
426 // Generations may keep statistics about collection. This
427 // method updates those statistics. current_level is
428 // the level of the collection that has most recently
429 // occurred. This allows the generation to decide what
430 // statistics are valid to collect. For example, the
431 // generation can decide to gather the amount of promoted data
432 // if the collection of the younger generations has completed.
433 GCStats* gc_stats() const { return _gc_stats; }
434 virtual void update_gc_stats(int current_level, bool full) {}
435
436 // Mark sweep support phase2
437 virtual void prepare_for_compaction(CompactPoint* cp);
438 // Mark sweep support phase3
439 virtual void adjust_pointers();
440 // Mark sweep support phase4
441 virtual void compact();
442 virtual void post_compact() {ShouldNotReachHere();}
443
444 // Support for CMS's rescan. In this general form we return a pointer
445 // to an abstract object that can be used, based on specific previously
446 // decided protocols, to exchange information between generations,
447 // information that may be useful for speeding up certain types of
448 // garbage collectors. A NULL value indicates to the client that
449 // no data recording is expected by the provider. The data-recorder is
450 // expected to be GC worker thread-local, with the worker index
451 // indicated by "thr_num".
452 virtual void* get_data_recorder(int thr_num) { return NULL; }
453 virtual void sample_eden_chunk() {}
454
455 // Some generations may require some cleanup actions before allowing
456 // a verification.
457 virtual void prepare_for_verify() {};
458
459 // Accessing "marks".
460
461 // This function gives a generation a chance to note a point between
462 // collections. For example, a contiguous generation might note the
463 // beginning allocation point post-collection, which might allow some later
464 // operations to be optimized.
465 virtual void save_marks() {}
466
467 // This function allows generations to initialize any "saved marks". That
468 // is, should only be called when the generation is empty.
469 virtual void reset_saved_marks() {}
470
471 // This function is "true" iff any no allocations have occurred in the
472 // generation since the last call to "save_marks".
473 virtual bool no_allocs_since_save_marks() = 0;
474
475 // Apply "cl->apply" to (the addresses of) all reference fields in objects
476 // allocated in the current generation since the last call to "save_marks".
477 // If more objects are allocated in this generation as a result of applying
478 // the closure, iterates over reference fields in those objects as well.
479 // Calls "save_marks" at the end of the iteration.
480 // General signature...
481 virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0;
482 // ...and specializations for de-virtualization. (The general
483 // implementation of the _nv versions call the virtual version.
484 // Note that the _nv suffix is not really semantically necessary,
485 // but it avoids some not-so-useful warnings on Solaris.)
486 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
487 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
488 oop_since_save_marks_iterate_v((OopsInGenClosure*)cl); \
489 }
490 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL)
491
492 #undef Generation_SINCE_SAVE_MARKS_DECL
493
494 // The "requestor" generation is performing some garbage collection
495 // action for which it would be useful to have scratch space. If
496 // the target is not the requestor, no gc actions will be required
497 // of the target. The requestor promises to allocate no more than
498 // "max_alloc_words" in the target generation (via promotion say,
499 // if the requestor is a young generation and the target is older).
500 // If the target generation can provide any scratch space, it adds
501 // it to "list", leaving "list" pointing to the head of the
502 // augmented list. The default is to offer no space.
503 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
504 size_t max_alloc_words) {}
505
506 // Give each generation an opportunity to do clean up for any
507 // contributed scratch.
508 virtual void reset_scratch() {};
509
510 // When an older generation has been collected, and perhaps resized,
511 // this method will be invoked on all younger generations (from older to
512 // younger), allowing them to resize themselves as appropriate.
513 virtual void compute_new_size() = 0;
514
515 // Printing
516 virtual const char* name() const = 0;
517 virtual const char* short_name() const = 0;
518
519 int level() const { return _level; }
520
521 // Attributes
522
523 // True iff the given generation may only be the youngest generation.
524 virtual bool must_be_youngest() const = 0;
525 // True iff the given generation may only be the oldest generation.
526 virtual bool must_be_oldest() const = 0;
527
528 // Reference Processing accessor
529 ReferenceProcessor* const ref_processor() { return _ref_processor; }
530
531 // Iteration.
532
533 // Iterate over all the ref-containing fields of all objects in the
534 // generation, calling "cl.do_oop" on each.
535 virtual void oop_iterate(ExtendedOopClosure* cl);
536
537 // Iterate over all objects in the generation, calling "cl.do_object" on
538 // each.
539 virtual void object_iterate(ObjectClosure* cl);
540
541 // Iterate over all safe objects in the generation, calling "cl.do_object" on
542 // each. An object is safe if its references point to other objects in
543 // the heap. This defaults to object_iterate() unless overridden.
544 virtual void safe_object_iterate(ObjectClosure* cl);
545
546 // Apply "cl->do_oop" to (the address of) all and only all the ref fields
547 // in the current generation that contain pointers to objects in younger
548 // generations. Objects allocated since the last "save_marks" call are
549 // excluded.
550 virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0;
551
552 // Inform a generation that it longer contains references to objects
553 // in any younger generation. [e.g. Because younger gens are empty,
554 // clear the card table.]
555 virtual void clear_remembered_set() { }
556
557 // Inform a generation that some of its objects have moved. [e.g. The
558 // generation's spaces were compacted, invalidating the card table.]
559 virtual void invalidate_remembered_set() { }
560
561 // Block abstraction.
562
563 // Returns the address of the start of the "block" that contains the
564 // address "addr". We say "blocks" instead of "object" since some heaps
565 // may not pack objects densely; a chunk may either be an object or a
566 // non-object.
567 virtual HeapWord* block_start(const void* addr) const;
568
569 // Requires "addr" to be the start of a chunk, and returns its size.
570 // "addr + size" is required to be the start of a new chunk, or the end
571 // of the active area of the heap.
572 virtual size_t block_size(const HeapWord* addr) const ;
573
574 // Requires "addr" to be the start of a block, and returns "TRUE" iff
575 // the block is an object.
576 virtual bool block_is_obj(const HeapWord* addr) const;
577
578
579 // PrintGC, PrintGCDetails support
580 void print_heap_change(size_t prev_used) const;
581
582 // PrintHeapAtGC support
583 virtual void print() const;
584 virtual void print_on(outputStream* st) const;
585
586 virtual void verify() = 0;
587
588 struct StatRecord {
589 int invocations;
590 elapsedTimer accumulated_time;
591 StatRecord() :
592 invocations(0),
593 accumulated_time(elapsedTimer()) {}
594 };
595 private:
596 StatRecord _stat_record;
597 public:
598 StatRecord* stat_record() { return &_stat_record; }
599
600 virtual void print_summary_info();
601 virtual void print_summary_info_on(outputStream* st);
602
603 // Performance Counter support
604 virtual void update_counters() = 0;
605 virtual CollectorCounters* counters() { return _gc_counters; }
606 };
607
608 // Class CardGeneration is a generation that is covered by a card table,
609 // and uses a card-size block-offset array to implement block_start.
610
611 // class BlockOffsetArray;
612 // class BlockOffsetArrayContigSpace;
613 class BlockOffsetSharedArray;
614
615 class CardGeneration: public Generation {
616 friend class VMStructs;
617 protected:
618 // This is shared with other generations.
619 GenRemSet* _rs;
620 // This is local to this generation.
621 BlockOffsetSharedArray* _bts;
622
623 // current shrinking effect: this damps shrinking when the heap gets empty.
624 size_t _shrink_factor;
625
626 size_t _min_heap_delta_bytes; // Minimum amount to expand.
627
628 // Some statistics from before gc started.
629 // These are gathered in the gc_prologue (and should_collect)
630 // to control growing/shrinking policy in spite of promotions.
631 size_t _capacity_at_prologue;
632 size_t _used_at_prologue;
633
634 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
635 GenRemSet* remset);
636
637 public:
638
639 // Attempt to expand the generation by "bytes". Expand by at a
640 // minimum "expand_bytes". Return true if some amount (not
641 // necessarily the full "bytes") was done.
642 virtual bool expand(size_t bytes, size_t expand_bytes);
643
644 // Shrink generation with specified size (returns false if unable to shrink)
645 virtual void shrink(size_t bytes) = 0;
646
647 virtual void compute_new_size();
648
649 virtual void clear_remembered_set();
650
651 virtual void invalidate_remembered_set();
652
653 virtual void prepare_for_verify();
654
655 // Grow generation with specified size (returns false if unable to grow)
656 virtual bool grow_by(size_t bytes) = 0;
657 // Grow generation to reserved size.
658 virtual bool grow_to_reserved() = 0;
659 };
660
661 // OneContigSpaceCardGeneration models a heap of old objects contained in a single
662 // contiguous space.
663 //
664 // Garbage collection is performed using mark-compact.
665
666 class OneContigSpaceCardGeneration: public CardGeneration {
667 friend class VMStructs;
668 // Abstractly, this is a subtype that gets access to protected fields.
669 friend class VM_PopulateDumpSharedSpace;
670
671 protected:
672 ContiguousSpace* _the_space; // actual space holding objects
673 WaterMark _last_gc; // watermark between objects allocated before
674 // and after last GC.
675
676 // Grow generation with specified size (returns false if unable to grow)
677 virtual bool grow_by(size_t bytes);
678 // Grow generation to reserved size.
679 virtual bool grow_to_reserved();
680 // Shrink generation with specified size (returns false if unable to shrink)
681 void shrink_by(size_t bytes);
682
683 // Allocation failure
684 virtual bool expand(size_t bytes, size_t expand_bytes);
685 void shrink(size_t bytes);
686
687 // Accessing spaces
688 ContiguousSpace* the_space() const { return _the_space; }
689
690 public:
691 OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size,
692 int level, GenRemSet* remset,
693 ContiguousSpace* space) :
694 CardGeneration(rs, initial_byte_size, level, remset),
695 _the_space(space)
696 {}
697
698 inline bool is_in(const void* p) const;
699
700 // Space enquiries
701 size_t capacity() const;
702 size_t used() const;
703 size_t free() const;
704
705 MemRegion used_region() const;
706
707 size_t unsafe_max_alloc_nogc() const;
708 size_t contiguous_available() const;
709
710 // Iteration
711 void object_iterate(ObjectClosure* blk);
712 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
713
714 void younger_refs_iterate(OopsInGenClosure* blk);
715
716 inline CompactibleSpace* first_compaction_space() const;
717
718 virtual inline HeapWord* allocate(size_t word_size, bool is_tlab);
719 virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab);
720
721 // Accessing marks
722 inline WaterMark top_mark();
723 inline WaterMark bottom_mark();
724
725 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
726 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
727 OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v)
728 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL)
729
730 void save_marks();
731 void reset_saved_marks();
732 bool no_allocs_since_save_marks();
733
734 inline size_t block_size(const HeapWord* addr) const;
735
736 inline bool block_is_obj(const HeapWord* addr) const;
737
738 virtual void collect(bool full,
739 bool clear_all_soft_refs,
740 size_t size,
741 bool is_tlab);
742 HeapWord* expand_and_allocate(size_t size,
743 bool is_tlab,
744 bool parallel = false);
745
746 virtual void prepare_for_verify();
747
748 virtual void gc_epilogue(bool full);
749
750 virtual void record_spaces_top();
751
752 virtual void verify();
753 virtual void print_on(outputStream* st) const;
754 };
755
756 #endif // SHARE_VM_MEMORY_GENERATION_HPP