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_GC_SHARED_SPACE_HPP
26 #define SHARE_VM_GC_SHARED_SPACE_HPP
27
28 #include "gc/shared/blockOffsetTable.hpp"
29 #include "gc/shared/cardTableModRefBS.hpp"
30 #include "gc/shared/workgroup.hpp"
31 #include "memory/allocation.hpp"
32 #include "memory/iterator.hpp"
33 #include "memory/memRegion.hpp"
34 #include "oops/markOop.hpp"
35 #include "runtime/mutexLocker.hpp"
36 #include "utilities/align.hpp"
37 #include "utilities/macros.hpp"
38
39 // A space is an abstraction for the "storage units" backing
40 // up the generation abstraction. It includes specific
41 // implementations for keeping track of free and used space,
42 // for iterating over objects and free blocks, etc.
43
44 // Forward decls.
45 class Space;
46 class BlockOffsetArray;
47 class BlockOffsetArrayContigSpace;
48 class Generation;
49 class CompactibleSpace;
50 class BlockOffsetTable;
51 class CardTableRS;
52 class DirtyCardToOopClosure;
53
54 // A Space describes a heap area. Class Space is an abstract
55 // base class.
56 //
57 // Space supports allocation, size computation and GC support is provided.
58 //
59 // Invariant: bottom() and end() are on page_size boundaries and
60 // bottom() <= top() <= end()
61 // top() is inclusive and end() is exclusive.
62
63 class Space: public CHeapObj<mtGC> {
64 friend class VMStructs;
65 protected:
66 HeapWord* _bottom;
67 HeapWord* _end;
68
69 // Used in support of save_marks()
70 HeapWord* _saved_mark_word;
71
72 // A sequential tasks done structure. This supports
73 // parallel GC, where we have threads dynamically
74 // claiming sub-tasks from a larger parallel task.
75 SequentialSubTasksDone _par_seq_tasks;
76
77 Space():
78 _bottom(NULL), _end(NULL) { }
79
80 public:
81 // Accessors
82 HeapWord* bottom() const { return _bottom; }
83 HeapWord* end() const { return _end; }
84 virtual void set_bottom(HeapWord* value) { _bottom = value; }
85 virtual void set_end(HeapWord* value) { _end = value; }
86
87 virtual HeapWord* saved_mark_word() const { return _saved_mark_word; }
88
89 void set_saved_mark_word(HeapWord* p) { _saved_mark_word = p; }
90
91 // Returns true if this object has been allocated since a
92 // generation's "save_marks" call.
93 virtual bool obj_allocated_since_save_marks(const oop obj) const {
94 return (HeapWord*)obj >= saved_mark_word();
95 }
96
97 virtual MemRegionClosure* preconsumptionDirtyCardClosure() const {
98 return NULL;
99 }
100
101 // Returns a subregion of the space containing only the allocated objects in
102 // the space.
103 virtual MemRegion used_region() const = 0;
104
105 // Returns a region that is guaranteed to contain (at least) all objects
106 // allocated at the time of the last call to "save_marks". If the space
107 // initializes its DirtyCardToOopClosure's specifying the "contig" option
108 // (that is, if the space is contiguous), then this region must contain only
109 // such objects: the memregion will be from the bottom of the region to the
110 // saved mark. Otherwise, the "obj_allocated_since_save_marks" method of
111 // the space must distinguish between objects in the region allocated before
112 // and after the call to save marks.
113 MemRegion used_region_at_save_marks() const {
114 return MemRegion(bottom(), saved_mark_word());
115 }
116
117 // Initialization.
118 // "initialize" should be called once on a space, before it is used for
119 // any purpose. The "mr" arguments gives the bounds of the space, and
120 // the "clear_space" argument should be true unless the memory in "mr" is
121 // known to be zeroed.
122 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
123
124 // The "clear" method must be called on a region that may have
125 // had allocation performed in it, but is now to be considered empty.
126 virtual void clear(bool mangle_space);
127
128 // For detecting GC bugs. Should only be called at GC boundaries, since
129 // some unused space may be used as scratch space during GC's.
130 // We also call this when expanding a space to satisfy an allocation
131 // request. See bug #4668531
132 virtual void mangle_unused_area() = 0;
133 virtual void mangle_unused_area_complete() = 0;
134
135 // Testers
136 bool is_empty() const { return used() == 0; }
137 bool not_empty() const { return used() > 0; }
138
139 // Returns true iff the given the space contains the
140 // given address as part of an allocated object. For
141 // certain kinds of spaces, this might be a potentially
142 // expensive operation. To prevent performance problems
143 // on account of its inadvertent use in product jvm's,
144 // we restrict its use to assertion checks only.
145 bool is_in(const void* p) const {
146 return used_region().contains(p);
147 }
148
149 // Returns true iff the given reserved memory of the space contains the
150 // given address.
151 bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; }
152
153 // Returns true iff the given block is not allocated.
154 virtual bool is_free_block(const HeapWord* p) const = 0;
155
156 // Test whether p is double-aligned
157 static bool is_aligned(void* p) {
158 return ::is_aligned(p, sizeof(double));
159 }
160
161 // Size computations. Sizes are in bytes.
162 size_t capacity() const { return byte_size(bottom(), end()); }
163 virtual size_t used() const = 0;
164 virtual size_t free() const = 0;
165
166 // Iterate over all the ref-containing fields of all objects in the
167 // space, calling "cl.do_oop" on each. Fields in objects allocated by
168 // applications of the closure are not included in the iteration.
169 virtual void oop_iterate(ExtendedOopClosure* cl);
170
171 // Iterate over all objects in the space, calling "cl.do_object" on
172 // each. Objects allocated by applications of the closure are not
173 // included in the iteration.
174 virtual void object_iterate(ObjectClosure* blk) = 0;
175 // Similar to object_iterate() except only iterates over
176 // objects whose internal references point to objects in the space.
177 virtual void safe_object_iterate(ObjectClosure* blk) = 0;
178
179 // Create and return a new dirty card to oop closure. Can be
180 // overridden to return the appropriate type of closure
181 // depending on the type of space in which the closure will
182 // operate. ResourceArea allocated.
183 virtual DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,
184 CardTableModRefBS::PrecisionStyle precision,
185 HeapWord* boundary,
186 bool parallel);
187
188 // If "p" is in the space, returns the address of the start of the
189 // "block" that contains "p". We say "block" instead of "object" since
190 // some heaps may not pack objects densely; a chunk may either be an
191 // object or a non-object. If "p" is not in the space, return NULL.
192 virtual HeapWord* block_start_const(const void* p) const = 0;
193
194 // The non-const version may have benevolent side effects on the data
195 // structure supporting these calls, possibly speeding up future calls.
196 // The default implementation, however, is simply to call the const
197 // version.
198 virtual HeapWord* block_start(const void* p);
199
200 // Requires "addr" to be the start of a chunk, and returns its size.
201 // "addr + size" is required to be the start of a new chunk, or the end
202 // of the active area of the heap.
203 virtual size_t block_size(const HeapWord* addr) const = 0;
204
205 // Requires "addr" to be the start of a block, and returns "TRUE" iff
206 // the block is an object.
207 virtual bool block_is_obj(const HeapWord* addr) const = 0;
208
209 // Requires "addr" to be the start of a block, and returns "TRUE" iff
210 // the block is an object and the object is alive.
211 virtual bool obj_is_alive(const HeapWord* addr) const;
212
213 // Allocation (return NULL if full). Assumes the caller has established
214 // mutually exclusive access to the space.
215 virtual HeapWord* allocate(size_t word_size) = 0;
216
217 // Allocation (return NULL if full). Enforces mutual exclusion internally.
218 virtual HeapWord* par_allocate(size_t word_size) = 0;
219
220 // Mark-sweep-compact support: all spaces can update pointers to objects
221 // moving as a part of compaction.
222 virtual void adjust_pointers() = 0;
223
224 virtual void print() const;
225 virtual void print_on(outputStream* st) const;
226 virtual void print_short() const;
227 virtual void print_short_on(outputStream* st) const;
228
229
230 // Accessor for parallel sequential tasks.
231 SequentialSubTasksDone* par_seq_tasks() { return &_par_seq_tasks; }
232
233 // IF "this" is a ContiguousSpace, return it, else return NULL.
234 virtual ContiguousSpace* toContiguousSpace() {
235 return NULL;
236 }
237
238 // Debugging
239 virtual void verify() const = 0;
240 };
241
242 // A MemRegionClosure (ResourceObj) whose "do_MemRegion" function applies an
243 // OopClosure to (the addresses of) all the ref-containing fields that could
244 // be modified by virtue of the given MemRegion being dirty. (Note that
245 // because of the imprecise nature of the write barrier, this may iterate
246 // over oops beyond the region.)
247 // This base type for dirty card to oop closures handles memory regions
248 // in non-contiguous spaces with no boundaries, and should be sub-classed
249 // to support other space types. See ContiguousDCTOC for a sub-class
250 // that works with ContiguousSpaces.
251
252 class DirtyCardToOopClosure: public MemRegionClosureRO {
253 protected:
254 ExtendedOopClosure* _cl;
255 Space* _sp;
256 CardTableModRefBS::PrecisionStyle _precision;
257 HeapWord* _boundary; // If non-NULL, process only non-NULL oops
258 // pointing below boundary.
259 HeapWord* _min_done; // ObjHeadPreciseArray precision requires
260 // a downwards traversal; this is the
261 // lowest location already done (or,
262 // alternatively, the lowest address that
263 // shouldn't be done again. NULL means infinity.)
264 NOT_PRODUCT(HeapWord* _last_bottom;)
265 NOT_PRODUCT(HeapWord* _last_explicit_min_done;)
266
267 // Get the actual top of the area on which the closure will
268 // operate, given where the top is assumed to be (the end of the
269 // memory region passed to do_MemRegion) and where the object
270 // at the top is assumed to start. For example, an object may
271 // start at the top but actually extend past the assumed top,
272 // in which case the top becomes the end of the object.
273 virtual HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);
274
275 // Walk the given memory region from bottom to (actual) top
276 // looking for objects and applying the oop closure (_cl) to
277 // them. The base implementation of this treats the area as
278 // blocks, where a block may or may not be an object. Sub-
279 // classes should override this to provide more accurate
280 // or possibly more efficient walking.
281 virtual void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
282
283 public:
284 DirtyCardToOopClosure(Space* sp, ExtendedOopClosure* cl,
285 CardTableModRefBS::PrecisionStyle precision,
286 HeapWord* boundary) :
287 _sp(sp), _cl(cl), _precision(precision), _boundary(boundary),
288 _min_done(NULL) {
289 NOT_PRODUCT(_last_bottom = NULL);
290 NOT_PRODUCT(_last_explicit_min_done = NULL);
291 }
292
293 void do_MemRegion(MemRegion mr);
294
295 void set_min_done(HeapWord* min_done) {
296 _min_done = min_done;
297 NOT_PRODUCT(_last_explicit_min_done = _min_done);
298 }
299 #ifndef PRODUCT
300 void set_last_bottom(HeapWord* last_bottom) {
301 _last_bottom = last_bottom;
302 }
303 #endif
304 };
305
306 // A structure to represent a point at which objects are being copied
307 // during compaction.
308 class CompactPoint : public StackObj {
309 public:
310 Generation* gen;
311 CompactibleSpace* space;
312 HeapWord* threshold;
313
314 CompactPoint(Generation* g = NULL) :
315 gen(g), space(NULL), threshold(0) {}
316 };
317
318 // A space that supports compaction operations. This is usually, but not
319 // necessarily, a space that is normally contiguous. But, for example, a
320 // free-list-based space whose normal collection is a mark-sweep without
321 // compaction could still support compaction in full GC's.
322 //
323 // The compaction operations are implemented by the
324 // scan_and_{adjust_pointers,compact,forward} function templates.
325 // The following are, non-virtual, auxiliary functions used by these function templates:
326 // - scan_limit()
327 // - scanned_block_is_obj()
328 // - scanned_block_size()
329 // - adjust_obj_size()
330 // - obj_size()
331 // These functions are to be used exclusively by the scan_and_* function templates,
332 // and must be defined for all (non-abstract) subclasses of CompactibleSpace.
333 //
334 // NOTE: Any subclasses to CompactibleSpace wanting to change/define the behavior
335 // in any of the auxiliary functions must also override the corresponding
336 // prepare_for_compaction/adjust_pointers/compact functions using them.
337 // If not, such changes will not be used or have no effect on the compaction operations.
338 //
339 // This translates to the following dependencies:
340 // Overrides/definitions of
341 // - scan_limit
342 // - scanned_block_is_obj
343 // - scanned_block_size
344 // require override/definition of prepare_for_compaction().
345 // Similar dependencies exist between
346 // - adjust_obj_size and adjust_pointers()
347 // - obj_size and compact().
348 //
349 // Additionally, this also means that changes to block_size() or block_is_obj() that
350 // should be effective during the compaction operations must provide a corresponding
351 // definition of scanned_block_size/scanned_block_is_obj respectively.
352 class CompactibleSpace: public Space {
353 friend class VMStructs;
354 friend class CompactibleFreeListSpace;
355 private:
356 HeapWord* _compaction_top;
357 CompactibleSpace* _next_compaction_space;
358
359 // Auxiliary functions for scan_and_{forward,adjust_pointers,compact} support.
360 inline size_t adjust_obj_size(size_t size) const {
361 return size;
362 }
363
364 inline size_t obj_size(const HeapWord* addr) const;
365
366 template <class SpaceType>
367 static inline void verify_up_to_first_dead(SpaceType* space) NOT_DEBUG_RETURN;
368
369 template <class SpaceType>
370 static inline void clear_empty_region(SpaceType* space);
371
372 public:
373 CompactibleSpace() :
374 _compaction_top(NULL), _next_compaction_space(NULL) {}
375
376 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
377 virtual void clear(bool mangle_space);
378
379 // Used temporarily during a compaction phase to hold the value
380 // top should have when compaction is complete.
381 HeapWord* compaction_top() const { return _compaction_top; }
382
383 void set_compaction_top(HeapWord* value) {
384 assert(value == NULL || (value >= bottom() && value <= end()),
385 "should point inside space");
386 _compaction_top = value;
387 }
388
389 // Perform operations on the space needed after a compaction
390 // has been performed.
391 virtual void reset_after_compaction() = 0;
392
393 // Returns the next space (in the current generation) to be compacted in
394 // the global compaction order. Also is used to select the next
395 // space into which to compact.
396
397 virtual CompactibleSpace* next_compaction_space() const {
398 return _next_compaction_space;
399 }
400
401 void set_next_compaction_space(CompactibleSpace* csp) {
402 _next_compaction_space = csp;
403 }
404
405 // MarkSweep support phase2
406
407 // Start the process of compaction of the current space: compute
408 // post-compaction addresses, and insert forwarding pointers. The fields
409 // "cp->gen" and "cp->compaction_space" are the generation and space into
410 // which we are currently compacting. This call updates "cp" as necessary,
411 // and leaves the "compaction_top" of the final value of
412 // "cp->compaction_space" up-to-date. Offset tables may be updated in
413 // this phase as if the final copy had occurred; if so, "cp->threshold"
414 // indicates when the next such action should be taken.
415 virtual void prepare_for_compaction(CompactPoint* cp) = 0;
416 // MarkSweep support phase3
417 virtual void adjust_pointers();
418 // MarkSweep support phase4
419 virtual void compact();
420
421 // The maximum percentage of objects that can be dead in the compacted
422 // live part of a compacted space ("deadwood" support.)
423 virtual size_t allowed_dead_ratio() const { return 0; };
424
425 // Some contiguous spaces may maintain some data structures that should
426 // be updated whenever an allocation crosses a boundary. This function
427 // returns the first such boundary.
428 // (The default implementation returns the end of the space, so the
429 // boundary is never crossed.)
430 virtual HeapWord* initialize_threshold() { return end(); }
431
432 // "q" is an object of the given "size" that should be forwarded;
433 // "cp" names the generation ("gen") and containing "this" (which must
434 // also equal "cp->space"). "compact_top" is where in "this" the
435 // next object should be forwarded to. If there is room in "this" for
436 // the object, insert an appropriate forwarding pointer in "q".
437 // If not, go to the next compaction space (there must
438 // be one, since compaction must succeed -- we go to the first space of
439 // the previous generation if necessary, updating "cp"), reset compact_top
440 // and then forward. In either case, returns the new value of "compact_top".
441 // If the forwarding crosses "cp->threshold", invokes the "cross_threshold"
442 // function of the then-current compaction space, and updates "cp->threshold
443 // accordingly".
444 virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp,
445 HeapWord* compact_top);
446
447 // Return a size with adjustments as required of the space.
448 virtual size_t adjust_object_size_v(size_t size) const { return size; }
449
450 protected:
451 // Used during compaction.
452 HeapWord* _first_dead;
453 HeapWord* _end_of_live;
454
455 // Minimum size of a free block.
456 virtual size_t minimum_free_block_size() const { return 0; }
457
458 // This the function is invoked when an allocation of an object covering
459 // "start" to "end occurs crosses the threshold; returns the next
460 // threshold. (The default implementation does nothing.)
461 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* the_end) {
462 return end();
463 }
464
465 // Below are template functions for scan_and_* algorithms (avoiding virtual calls).
466 // The space argument should be a subclass of CompactibleSpace, implementing
467 // scan_limit(), scanned_block_is_obj(), and scanned_block_size(),
468 // and possibly also overriding obj_size(), and adjust_obj_size().
469 // These functions should avoid virtual calls whenever possible.
470
471 // Frequently calls adjust_obj_size().
472 template <class SpaceType>
473 static inline void scan_and_adjust_pointers(SpaceType* space);
474
475 // Frequently calls obj_size().
476 template <class SpaceType>
477 static inline void scan_and_compact(SpaceType* space);
478
479 // Frequently calls scanned_block_is_obj() and scanned_block_size().
480 // Requires the scan_limit() function.
481 template <class SpaceType>
482 static inline void scan_and_forward(SpaceType* space, CompactPoint* cp);
483 };
484
485 class GenSpaceMangler;
486
487 // A space in which the free area is contiguous. It therefore supports
488 // faster allocation, and compaction.
489 class ContiguousSpace: public CompactibleSpace {
490 friend class VMStructs;
491 // Allow scan_and_forward function to call (private) overrides for auxiliary functions on this class
492 template <typename SpaceType>
493 friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp);
494
495 private:
496 // Auxiliary functions for scan_and_forward support.
497 // See comments for CompactibleSpace for more information.
498 inline HeapWord* scan_limit() const {
499 return top();
500 }
501
502 inline bool scanned_block_is_obj(const HeapWord* addr) const {
503 return true; // Always true, since scan_limit is top
504 }
505
506 inline size_t scanned_block_size(const HeapWord* addr) const;
507
508 protected:
509 HeapWord* _top;
510 HeapWord* _concurrent_iteration_safe_limit;
511 // A helper for mangling the unused area of the space in debug builds.
512 GenSpaceMangler* _mangler;
513
514 GenSpaceMangler* mangler() { return _mangler; }
515
516 // Allocation helpers (return NULL if full).
517 inline HeapWord* allocate_impl(size_t word_size);
518 inline HeapWord* par_allocate_impl(size_t word_size);
519
520 public:
521 ContiguousSpace();
522 ~ContiguousSpace();
523
524 virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
525 virtual void clear(bool mangle_space);
526
527 // Accessors
528 HeapWord* top() const { return _top; }
529 void set_top(HeapWord* value) { _top = value; }
530
531 void set_saved_mark() { _saved_mark_word = top(); }
532 void reset_saved_mark() { _saved_mark_word = bottom(); }
533
534 bool saved_mark_at_top() const { return saved_mark_word() == top(); }
535
536 // In debug mode mangle (write it with a particular bit
537 // pattern) the unused part of a space.
538
539 // Used to save the an address in a space for later use during mangling.
540 void set_top_for_allocations(HeapWord* v) PRODUCT_RETURN;
541 // Used to save the space's current top for later use during mangling.
542 void set_top_for_allocations() PRODUCT_RETURN;
543
544 // Mangle regions in the space from the current top up to the
545 // previously mangled part of the space.
546 void mangle_unused_area() PRODUCT_RETURN;
547 // Mangle [top, end)
548 void mangle_unused_area_complete() PRODUCT_RETURN;
549
550 // Do some sparse checking on the area that should have been mangled.
551 void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;
552 // Check the complete area that should have been mangled.
553 // This code may be NULL depending on the macro DEBUG_MANGLING.
554 void check_mangled_unused_area_complete() PRODUCT_RETURN;
555
556 // Size computations: sizes in bytes.
557 size_t capacity() const { return byte_size(bottom(), end()); }
558 size_t used() const { return byte_size(bottom(), top()); }
559 size_t free() const { return byte_size(top(), end()); }
560
561 virtual bool is_free_block(const HeapWord* p) const;
562
563 // In a contiguous space we have a more obvious bound on what parts
564 // contain objects.
565 MemRegion used_region() const { return MemRegion(bottom(), top()); }
566
567 // Allocation (return NULL if full)
568 virtual HeapWord* allocate(size_t word_size);
569 virtual HeapWord* par_allocate(size_t word_size);
570 HeapWord* allocate_aligned(size_t word_size);
571
572 // Iteration
573 void oop_iterate(ExtendedOopClosure* cl);
574 void object_iterate(ObjectClosure* blk);
575 // For contiguous spaces this method will iterate safely over objects
576 // in the space (i.e., between bottom and top) when at a safepoint.
577 void safe_object_iterate(ObjectClosure* blk);
578
579 // Iterate over as many initialized objects in the space as possible,
580 // calling "cl.do_object_careful" on each. Return NULL if all objects
581 // in the space (at the start of the iteration) were iterated over.
582 // Return an address indicating the extent of the iteration in the
583 // event that the iteration had to return because of finding an
584 // uninitialized object in the space, or if the closure "cl"
585 // signaled early termination.
586 HeapWord* object_iterate_careful(ObjectClosureCareful* cl);
587 HeapWord* concurrent_iteration_safe_limit() {
588 assert(_concurrent_iteration_safe_limit <= top(),
589 "_concurrent_iteration_safe_limit update missed");
590 return _concurrent_iteration_safe_limit;
591 }
592 // changes the safe limit, all objects from bottom() to the new
593 // limit should be properly initialized
594 void set_concurrent_iteration_safe_limit(HeapWord* new_limit) {
595 assert(new_limit <= top(), "uninitialized objects in the safe range");
596 _concurrent_iteration_safe_limit = new_limit;
597 }
598
599
600 #if INCLUDE_ALL_GCS
601 // In support of parallel oop_iterate.
602 #define ContigSpace_PAR_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
603 void par_oop_iterate(MemRegion mr, OopClosureType* blk);
604
605 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DECL)
606 #undef ContigSpace_PAR_OOP_ITERATE_DECL
607 #endif // INCLUDE_ALL_GCS
608
609 // Compaction support
610 virtual void reset_after_compaction() {
611 assert(compaction_top() >= bottom() && compaction_top() <= end(), "should point inside space");
612 set_top(compaction_top());
613 // set new iteration safe limit
614 set_concurrent_iteration_safe_limit(compaction_top());
615 }
616
617 // Override.
618 DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,
619 CardTableModRefBS::PrecisionStyle precision,
620 HeapWord* boundary,
621 bool parallel);
622
623 // Apply "blk->do_oop" to the addresses of all reference fields in objects
624 // starting with the _saved_mark_word, which was noted during a generation's
625 // save_marks and is required to denote the head of an object.
626 // Fields in objects allocated by applications of the closure
627 // *are* included in the iteration.
628 // Updates _saved_mark_word to point to just after the last object
629 // iterated over.
630 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
631 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk);
632
633 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DECL)
634 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DECL
635
636 // Same as object_iterate, but starting from "mark", which is required
637 // to denote the start of an object. Objects allocated by
638 // applications of the closure *are* included in the iteration.
639 virtual void object_iterate_from(HeapWord* mark, ObjectClosure* blk);
640
641 // Very inefficient implementation.
642 virtual HeapWord* block_start_const(const void* p) const;
643 size_t block_size(const HeapWord* p) const;
644 // If a block is in the allocated area, it is an object.
645 bool block_is_obj(const HeapWord* p) const { return p < top(); }
646
647 // Addresses for inlined allocation
648 HeapWord** top_addr() { return &_top; }
649 HeapWord** end_addr() { return &_end; }
650
651 // Overrides for more efficient compaction support.
652 void prepare_for_compaction(CompactPoint* cp);
653
654 virtual void print_on(outputStream* st) const;
655
656 // Checked dynamic downcasts.
657 virtual ContiguousSpace* toContiguousSpace() {
658 return this;
659 }
660
661 // Debugging
662 virtual void verify() const;
663
664 // Used to increase collection frequency. "factor" of 0 means entire
665 // space.
666 void allocate_temporary_filler(int factor);
667 };
668
669
670 // A dirty card to oop closure that does filtering.
671 // It knows how to filter out objects that are outside of the _boundary.
672 class FilteringDCTOC : public DirtyCardToOopClosure {
673 protected:
674 // Override.
675 void walk_mem_region(MemRegion mr,
676 HeapWord* bottom, HeapWord* top);
677
678 // Walk the given memory region, from bottom to top, applying
679 // the given oop closure to (possibly) all objects found. The
680 // given oop closure may or may not be the same as the oop
681 // closure with which this closure was created, as it may
682 // be a filtering closure which makes use of the _boundary.
683 // We offer two signatures, so the FilteringClosure static type is
684 // apparent.
685 virtual void walk_mem_region_with_cl(MemRegion mr,
686 HeapWord* bottom, HeapWord* top,
687 ExtendedOopClosure* cl) = 0;
688 virtual void walk_mem_region_with_cl(MemRegion mr,
689 HeapWord* bottom, HeapWord* top,
690 FilteringClosure* cl) = 0;
691
692 public:
693 FilteringDCTOC(Space* sp, ExtendedOopClosure* cl,
694 CardTableModRefBS::PrecisionStyle precision,
695 HeapWord* boundary) :
696 DirtyCardToOopClosure(sp, cl, precision, boundary) {}
697 };
698
699 // A dirty card to oop closure for contiguous spaces
700 // (ContiguousSpace and sub-classes).
701 // It is a FilteringClosure, as defined above, and it knows:
702 //
703 // 1. That the actual top of any area in a memory region
704 // contained by the space is bounded by the end of the contiguous
705 // region of the space.
706 // 2. That the space is really made up of objects and not just
707 // blocks.
708
709 class ContiguousSpaceDCTOC : public FilteringDCTOC {
710 protected:
711 // Overrides.
712 HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);
713
714 virtual void walk_mem_region_with_cl(MemRegion mr,
715 HeapWord* bottom, HeapWord* top,
716 ExtendedOopClosure* cl);
717 virtual void walk_mem_region_with_cl(MemRegion mr,
718 HeapWord* bottom, HeapWord* top,
719 FilteringClosure* cl);
720
721 public:
722 ContiguousSpaceDCTOC(ContiguousSpace* sp, ExtendedOopClosure* cl,
723 CardTableModRefBS::PrecisionStyle precision,
724 HeapWord* boundary) :
725 FilteringDCTOC(sp, cl, precision, boundary)
726 {}
727 };
728
729 // A ContigSpace that Supports an efficient "block_start" operation via
730 // a BlockOffsetArray (whose BlockOffsetSharedArray may be shared with
731 // other spaces.) This is the abstract base class for old generation
732 // (tenured) spaces.
733
734 class OffsetTableContigSpace: public ContiguousSpace {
735 friend class VMStructs;
736 protected:
737 BlockOffsetArrayContigSpace _offsets;
738 Mutex _par_alloc_lock;
739
740 public:
741 // Constructor
742 OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
743 MemRegion mr);
744
745 void set_bottom(HeapWord* value);
746 void set_end(HeapWord* value);
747
748 void clear(bool mangle_space);
749
750 inline HeapWord* block_start_const(const void* p) const;
751
752 // Add offset table update.
753 virtual inline HeapWord* allocate(size_t word_size);
754 inline HeapWord* par_allocate(size_t word_size);
755
756 // MarkSweep support phase3
757 virtual HeapWord* initialize_threshold();
758 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
759
760 virtual void print_on(outputStream* st) const;
761
762 // Debugging
763 void verify() const;
764 };
765
766
767 // Class TenuredSpace is used by TenuredGeneration
768
769 class TenuredSpace: public OffsetTableContigSpace {
770 friend class VMStructs;
771 protected:
772 // Mark sweep support
773 size_t allowed_dead_ratio() const;
774 public:
775 // Constructor
776 TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray,
777 MemRegion mr) :
778 OffsetTableContigSpace(sharedOffsetArray, mr) {}
779 };
780 #endif // SHARE_VM_GC_SHARED_SPACE_HPP