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comparison src/share/vm/memory/generation.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ba764ed4b6f2 |
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1 /* | |
2 * Copyright 1997-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // A Generation models a heap area for similarly-aged objects. | |
26 // It will contain one ore more spaces holding the actual objects. | |
27 // | |
28 // The Generation class hierarchy: | |
29 // | |
30 // Generation - abstract base class | |
31 // - DefNewGeneration - allocation area (copy collected) | |
32 // - ParNewGeneration - a DefNewGeneration that is collected by | |
33 // several threads | |
34 // - CardGeneration - abstract class adding offset array behavior | |
35 // - OneContigSpaceCardGeneration - abstract class holding a single | |
36 // contiguous space with card marking | |
37 // - TenuredGeneration - tenured (old object) space (markSweepCompact) | |
38 // - CompactingPermGenGen - reflective object area (klasses, methods, symbols, ...) | |
39 // - ConcurrentMarkSweepGeneration - Mostly Concurrent Mark Sweep Generation | |
40 // (Detlefs-Printezis refinement of | |
41 // Boehm-Demers-Schenker) | |
42 // | |
43 // The system configurations currently allowed are: | |
44 // | |
45 // DefNewGeneration + TenuredGeneration + PermGeneration | |
46 // DefNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen | |
47 // | |
48 // ParNewGeneration + TenuredGeneration + PermGeneration | |
49 // ParNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen | |
50 // | |
51 | |
52 class DefNewGeneration; | |
53 class GenerationSpec; | |
54 class CompactibleSpace; | |
55 class ContiguousSpace; | |
56 class CompactPoint; | |
57 class OopsInGenClosure; | |
58 class OopClosure; | |
59 class ScanClosure; | |
60 class FastScanClosure; | |
61 class GenCollectedHeap; | |
62 class GenRemSet; | |
63 class GCStats; | |
64 | |
65 // A "ScratchBlock" represents a block of memory in one generation usable by | |
66 // another. It represents "num_words" free words, starting at and including | |
67 // the address of "this". | |
68 struct ScratchBlock { | |
69 ScratchBlock* next; | |
70 size_t num_words; | |
71 HeapWord scratch_space[1]; // Actually, of size "num_words-2" (assuming | |
72 // first two fields are word-sized.) | |
73 }; | |
74 | |
75 | |
76 class Generation: public CHeapObj { | |
77 friend class VMStructs; | |
78 private: | |
79 jlong _time_of_last_gc; // time when last gc on this generation happened (ms) | |
80 MemRegion _prev_used_region; // for collectors that want to "remember" a value for | |
81 // used region at some specific point during collection. | |
82 | |
83 protected: | |
84 // Minimum and maximum addresses for memory reserved (not necessarily | |
85 // committed) for generation. | |
86 // Used by card marking code. Must not overlap with address ranges of | |
87 // other generations. | |
88 MemRegion _reserved; | |
89 | |
90 // Memory area reserved for generation | |
91 VirtualSpace _virtual_space; | |
92 | |
93 // Level in the generation hierarchy. | |
94 int _level; | |
95 | |
96 // ("Weak") Reference processing support | |
97 ReferenceProcessor* _ref_processor; | |
98 | |
99 // Performance Counters | |
100 CollectorCounters* _gc_counters; | |
101 | |
102 // Statistics for garbage collection | |
103 GCStats* _gc_stats; | |
104 | |
105 // Returns the next generation in the configuration, or else NULL if this | |
106 // is the highest generation. | |
107 Generation* next_gen() const; | |
108 | |
109 // Initialize the generation. | |
110 Generation(ReservedSpace rs, size_t initial_byte_size, int level); | |
111 | |
112 // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in | |
113 // "sp" that point into younger generations. | |
114 // The iteration is only over objects allocated at the start of the | |
115 // iterations; objects allocated as a result of applying the closure are | |
116 // not included. | |
117 void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl); | |
118 | |
119 public: | |
120 // The set of possible generation kinds. | |
121 enum Name { | |
122 ASParNew, | |
123 ASConcurrentMarkSweep, | |
124 DefNew, | |
125 ParNew, | |
126 MarkSweepCompact, | |
127 ConcurrentMarkSweep, | |
128 Other | |
129 }; | |
130 | |
131 enum SomePublicConstants { | |
132 // Generations are GenGrain-aligned and have size that are multiples of | |
133 // GenGrain. | |
134 LogOfGenGrain = 16, | |
135 GenGrain = 1 << LogOfGenGrain | |
136 }; | |
137 | |
138 // allocate and initialize ("weak") refs processing support | |
139 virtual void ref_processor_init(); | |
140 void set_ref_processor(ReferenceProcessor* rp) { | |
141 assert(_ref_processor == NULL, "clobbering existing _ref_processor"); | |
142 _ref_processor = rp; | |
143 } | |
144 | |
145 virtual Generation::Name kind() { return Generation::Other; } | |
146 GenerationSpec* spec(); | |
147 | |
148 // This properly belongs in the collector, but for now this | |
149 // will do. | |
150 virtual bool refs_discovery_is_atomic() const { return true; } | |
151 virtual bool refs_discovery_is_mt() const { return false; } | |
152 | |
153 // Space enquiries (results in bytes) | |
154 virtual size_t capacity() const = 0; // The maximum number of object bytes the | |
155 // generation can currently hold. | |
156 virtual size_t used() const = 0; // The number of used bytes in the gen. | |
157 virtual size_t free() const = 0; // The number of free bytes in the gen. | |
158 | |
159 // Support for java.lang.Runtime.maxMemory(); see CollectedHeap. | |
160 // Returns the total number of bytes available in a generation | |
161 // for the allocation of objects. | |
162 virtual size_t max_capacity() const; | |
163 | |
164 // If this is a young generation, the maximum number of bytes that can be | |
165 // allocated in this generation before a GC is triggered. | |
166 virtual size_t capacity_before_gc() const { return 0; } | |
167 | |
168 // The largest number of contiguous free bytes in the generation, | |
169 // including expansion (Assumes called at a safepoint.) | |
170 virtual size_t contiguous_available() const = 0; | |
171 // The largest number of contiguous free bytes in this or any higher generation. | |
172 virtual size_t max_contiguous_available() const; | |
173 | |
174 // Returns true if promotions of the specified amount can | |
175 // be attempted safely (without a vm failure). | |
176 // Promotion of the full amount is not guaranteed but | |
177 // can be attempted. | |
178 // younger_handles_promotion_failure | |
179 // is true if the younger generation handles a promotion | |
180 // failure. | |
181 virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes, | |
182 bool younger_handles_promotion_failure) const; | |
183 | |
184 // Return an estimate of the maximum allocation that could be performed | |
185 // in the generation without triggering any collection or expansion | |
186 // activity. It is "unsafe" because no locks are taken; the result | |
187 // should be treated as an approximation, not a guarantee, for use in | |
188 // heuristic resizing decisions. | |
189 virtual size_t unsafe_max_alloc_nogc() const = 0; | |
190 | |
191 // Returns true if this generation cannot be expanded further | |
192 // without a GC. Override as appropriate. | |
193 virtual bool is_maximal_no_gc() const { | |
194 return _virtual_space.uncommitted_size() == 0; | |
195 } | |
196 | |
197 MemRegion reserved() const { return _reserved; } | |
198 | |
199 // Returns a region guaranteed to contain all the objects in the | |
200 // generation. | |
201 virtual MemRegion used_region() const { return _reserved; } | |
202 | |
203 MemRegion prev_used_region() const { return _prev_used_region; } | |
204 virtual void save_used_region() { _prev_used_region = used_region(); } | |
205 | |
206 // Returns "TRUE" iff "p" points into an allocated object in the generation. | |
207 // For some kinds of generations, this may be an expensive operation. | |
208 // To avoid performance problems stemming from its inadvertent use in | |
209 // product jvm's, we restrict its use to assertion checking or | |
210 // verification only. | |
211 virtual bool is_in(const void* p) const; | |
212 | |
213 /* Returns "TRUE" iff "p" points into the reserved area of the generation. */ | |
214 bool is_in_reserved(const void* p) const { | |
215 return _reserved.contains(p); | |
216 } | |
217 | |
218 // Check that the generation kind is DefNewGeneration or a sub | |
219 // class of DefNewGeneration and return a DefNewGeneration* | |
220 DefNewGeneration* as_DefNewGeneration(); | |
221 | |
222 // If some space in the generation contains the given "addr", return a | |
223 // pointer to that space, else return "NULL". | |
224 virtual Space* space_containing(const void* addr) const; | |
225 | |
226 // Iteration - do not use for time critical operations | |
227 virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0; | |
228 | |
229 // Returns the first space, if any, in the generation that can participate | |
230 // in compaction, or else "NULL". | |
231 virtual CompactibleSpace* first_compaction_space() const = 0; | |
232 | |
233 // Returns "true" iff this generation should be used to allocate an | |
234 // object of the given size. Young generations might | |
235 // wish to exclude very large objects, for example, since, if allocated | |
236 // often, they would greatly increase the frequency of young-gen | |
237 // collection. | |
238 virtual bool should_allocate(size_t word_size, bool is_tlab) { | |
239 bool result = false; | |
240 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize); | |
241 if (!is_tlab || supports_tlab_allocation()) { | |
242 result = (word_size > 0) && (word_size < overflow_limit); | |
243 } | |
244 return result; | |
245 } | |
246 | |
247 // Allocate and returns a block of the requested size, or returns "NULL". | |
248 // Assumes the caller has done any necessary locking. | |
249 virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0; | |
250 | |
251 // Like "allocate", but performs any necessary locking internally. | |
252 virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0; | |
253 | |
254 // A 'younger' gen has reached an allocation limit, and uses this to notify | |
255 // the next older gen. The return value is a new limit, or NULL if none. The | |
256 // caller must do the necessary locking. | |
257 virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top, | |
258 size_t word_size) { | |
259 return NULL; | |
260 } | |
261 | |
262 // Some generation may offer a region for shared, contiguous allocation, | |
263 // via inlined code (by exporting the address of the top and end fields | |
264 // defining the extent of the contiguous allocation region.) | |
265 | |
266 // This function returns "true" iff the heap supports this kind of | |
267 // allocation. (More precisely, this means the style of allocation that | |
268 // increments *top_addr()" with a CAS.) (Default is "no".) | |
269 // A generation that supports this allocation style must use lock-free | |
270 // allocation for *all* allocation, since there are times when lock free | |
271 // allocation will be concurrent with plain "allocate" calls. | |
272 virtual bool supports_inline_contig_alloc() const { return false; } | |
273 | |
274 // These functions return the addresses of the fields that define the | |
275 // boundaries of the contiguous allocation area. (These fields should be | |
276 // physicall near to one another.) | |
277 virtual HeapWord** top_addr() const { return NULL; } | |
278 virtual HeapWord** end_addr() const { return NULL; } | |
279 | |
280 // Thread-local allocation buffers | |
281 virtual bool supports_tlab_allocation() const { return false; } | |
282 virtual size_t tlab_capacity() const { | |
283 guarantee(false, "Generation doesn't support thread local allocation buffers"); | |
284 return 0; | |
285 } | |
286 virtual size_t unsafe_max_tlab_alloc() const { | |
287 guarantee(false, "Generation doesn't support thread local allocation buffers"); | |
288 return 0; | |
289 } | |
290 | |
291 // "obj" is the address of an object in a younger generation. Allocate space | |
292 // for "obj" in the current (or some higher) generation, and copy "obj" into | |
293 // the newly allocated space, if possible, returning the result (or NULL if | |
294 // the allocation failed). | |
295 // | |
296 // The "obj_size" argument is just obj->size(), passed along so the caller can | |
297 // avoid repeating the virtual call to retrieve it. | |
298 // | |
299 // The "ref" argument, if non-NULL, is the address of some reference to "obj" | |
300 // (that is "*ref == obj"); some generations may use this information to, for | |
301 // example, influence placement decisions. | |
302 // | |
303 // The default implementation ignores "ref" and calls allocate(). | |
304 virtual oop promote(oop obj, size_t obj_size, oop* ref); | |
305 | |
306 // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote | |
307 // object "obj", whose original mark word was "m", and whose size is | |
308 // "word_sz". If possible, allocate space for "obj", copy obj into it | |
309 // (taking care to copy "m" into the mark word when done, since the mark | |
310 // word of "obj" may have been overwritten with a forwarding pointer, and | |
311 // also taking care to copy the klass pointer *last*. Returns the new | |
312 // object if successful, or else NULL. | |
313 virtual oop par_promote(int thread_num, | |
314 oop obj, markOop m, size_t word_sz); | |
315 | |
316 // Undo, if possible, the most recent par_promote_alloc allocation by | |
317 // "thread_num" ("obj", of "word_sz"). | |
318 virtual void par_promote_alloc_undo(int thread_num, | |
319 HeapWord* obj, size_t word_sz); | |
320 | |
321 // Informs the current generation that all par_promote_alloc's in the | |
322 // collection have been completed; any supporting data structures can be | |
323 // reset. Default is to do nothing. | |
324 virtual void par_promote_alloc_done(int thread_num) {} | |
325 | |
326 // Informs the current generation that all oop_since_save_marks_iterates | |
327 // performed by "thread_num" in the current collection, if any, have been | |
328 // completed; any supporting data structures can be reset. Default is to | |
329 // do nothing. | |
330 virtual void par_oop_since_save_marks_iterate_done(int thread_num) {} | |
331 | |
332 // This generation will collect all younger generations | |
333 // during a full collection. | |
334 virtual bool full_collects_younger_generations() const { return false; } | |
335 | |
336 // This generation does in-place marking, meaning that mark words | |
337 // are mutated during the marking phase and presumably reinitialized | |
338 // to a canonical value after the GC. This is currently used by the | |
339 // biased locking implementation to determine whether additional | |
340 // work is required during the GC prologue and epilogue. | |
341 virtual bool performs_in_place_marking() const { return true; } | |
342 | |
343 // Returns "true" iff collect() should subsequently be called on this | |
344 // this generation. See comment below. | |
345 // This is a generic implementation which can be overridden. | |
346 // | |
347 // Note: in the current (1.4) implementation, when genCollectedHeap's | |
348 // incremental_collection_will_fail flag is set, all allocations are | |
349 // slow path (the only fast-path place to allocate is DefNew, which | |
350 // will be full if the flag is set). | |
351 // Thus, older generations which collect younger generations should | |
352 // test this flag and collect if it is set. | |
353 virtual bool should_collect(bool full, | |
354 size_t word_size, | |
355 bool is_tlab) { | |
356 return (full || should_allocate(word_size, is_tlab)); | |
357 } | |
358 | |
359 // Perform a garbage collection. | |
360 // If full is true attempt a full garbage collection of this generation. | |
361 // Otherwise, attempting to (at least) free enough space to support an | |
362 // allocation of the given "word_size". | |
363 virtual void collect(bool full, | |
364 bool clear_all_soft_refs, | |
365 size_t word_size, | |
366 bool is_tlab) = 0; | |
367 | |
368 // Perform a heap collection, attempting to create (at least) enough | |
369 // space to support an allocation of the given "word_size". If | |
370 // successful, perform the allocation and return the resulting | |
371 // "oop" (initializing the allocated block). If the allocation is | |
372 // still unsuccessful, return "NULL". | |
373 virtual HeapWord* expand_and_allocate(size_t word_size, | |
374 bool is_tlab, | |
375 bool parallel = false) = 0; | |
376 | |
377 // Some generations may require some cleanup or preparation actions before | |
378 // allowing a collection. The default is to do nothing. | |
379 virtual void gc_prologue(bool full) {}; | |
380 | |
381 // Some generations may require some cleanup actions after a collection. | |
382 // The default is to do nothing. | |
383 virtual void gc_epilogue(bool full) {}; | |
384 | |
385 // Some generations may need to be "fixed-up" after some allocation | |
386 // activity to make them parsable again. The default is to do nothing. | |
387 virtual void ensure_parsability() {}; | |
388 | |
389 // Time (in ms) when we were last collected or now if a collection is | |
390 // in progress. | |
391 virtual jlong time_of_last_gc(jlong now) { | |
392 // XXX See note in genCollectedHeap::millis_since_last_gc() | |
393 NOT_PRODUCT( | |
394 if (now < _time_of_last_gc) { | |
395 warning("time warp: %d to %d", _time_of_last_gc, now); | |
396 } | |
397 ) | |
398 return _time_of_last_gc; | |
399 } | |
400 | |
401 virtual void update_time_of_last_gc(jlong now) { | |
402 _time_of_last_gc = now; | |
403 } | |
404 | |
405 // Generations may keep statistics about collection. This | |
406 // method updates those statistics. current_level is | |
407 // the level of the collection that has most recently | |
408 // occurred. This allows the generation to decide what | |
409 // statistics are valid to collect. For example, the | |
410 // generation can decide to gather the amount of promoted data | |
411 // if the collection of the younger generations has completed. | |
412 GCStats* gc_stats() const { return _gc_stats; } | |
413 virtual void update_gc_stats(int current_level, bool full) {} | |
414 | |
415 // Mark sweep support phase2 | |
416 virtual void prepare_for_compaction(CompactPoint* cp); | |
417 // Mark sweep support phase3 | |
418 virtual void pre_adjust_pointers() {ShouldNotReachHere();} | |
419 virtual void adjust_pointers(); | |
420 // Mark sweep support phase4 | |
421 virtual void compact(); | |
422 virtual void post_compact() {ShouldNotReachHere();} | |
423 | |
424 // Support for CMS's rescan. In this general form we return a pointer | |
425 // to an abstract object that can be used, based on specific previously | |
426 // decided protocols, to exchange information between generations, | |
427 // information that may be useful for speeding up certain types of | |
428 // garbage collectors. A NULL value indicates to the client that | |
429 // no data recording is expected by the provider. The data-recorder is | |
430 // expected to be GC worker thread-local, with the worker index | |
431 // indicated by "thr_num". | |
432 virtual void* get_data_recorder(int thr_num) { return NULL; } | |
433 | |
434 // Some generations may require some cleanup actions before allowing | |
435 // a verification. | |
436 virtual void prepare_for_verify() {}; | |
437 | |
438 // Accessing "marks". | |
439 | |
440 // This function gives a generation a chance to note a point between | |
441 // collections. For example, a contiguous generation might note the | |
442 // beginning allocation point post-collection, which might allow some later | |
443 // operations to be optimized. | |
444 virtual void save_marks() {} | |
445 | |
446 // This function allows generations to initialize any "saved marks". That | |
447 // is, should only be called when the generation is empty. | |
448 virtual void reset_saved_marks() {} | |
449 | |
450 // This function is "true" iff any no allocations have occurred in the | |
451 // generation since the last call to "save_marks". | |
452 virtual bool no_allocs_since_save_marks() = 0; | |
453 | |
454 // Apply "cl->apply" to (the addresses of) all reference fields in objects | |
455 // allocated in the current generation since the last call to "save_marks". | |
456 // If more objects are allocated in this generation as a result of applying | |
457 // the closure, iterates over reference fields in those objects as well. | |
458 // Calls "save_marks" at the end of the iteration. | |
459 // General signature... | |
460 virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0; | |
461 // ...and specializations for de-virtualization. (The general | |
462 // implemention of the _nv versions call the virtual version. | |
463 // Note that the _nv suffix is not really semantically necessary, | |
464 // but it avoids some not-so-useful warnings on Solaris.) | |
465 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
466 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
467 oop_since_save_marks_iterate_v((OopsInGenClosure*)cl); \ | |
468 } | |
469 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL) | |
470 | |
471 #undef Generation_SINCE_SAVE_MARKS_DECL | |
472 | |
473 // The "requestor" generation is performing some garbage collection | |
474 // action for which it would be useful to have scratch space. If | |
475 // the target is not the requestor, no gc actions will be required | |
476 // of the target. The requestor promises to allocate no more than | |
477 // "max_alloc_words" in the target generation (via promotion say, | |
478 // if the requestor is a young generation and the target is older). | |
479 // If the target generation can provide any scratch space, it adds | |
480 // it to "list", leaving "list" pointing to the head of the | |
481 // augmented list. The default is to offer no space. | |
482 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, | |
483 size_t max_alloc_words) {} | |
484 | |
485 // When an older generation has been collected, and perhaps resized, | |
486 // this method will be invoked on all younger generations (from older to | |
487 // younger), allowing them to resize themselves as appropriate. | |
488 virtual void compute_new_size() = 0; | |
489 | |
490 // Printing | |
491 virtual const char* name() const = 0; | |
492 virtual const char* short_name() const = 0; | |
493 | |
494 int level() const { return _level; } | |
495 | |
496 // Attributes | |
497 | |
498 // True iff the given generation may only be the youngest generation. | |
499 virtual bool must_be_youngest() const = 0; | |
500 // True iff the given generation may only be the oldest generation. | |
501 virtual bool must_be_oldest() const = 0; | |
502 | |
503 // Reference Processing accessor | |
504 ReferenceProcessor* const ref_processor() { return _ref_processor; } | |
505 | |
506 // Iteration. | |
507 | |
508 // Iterate over all the ref-containing fields of all objects in the | |
509 // generation, calling "cl.do_oop" on each. | |
510 virtual void oop_iterate(OopClosure* cl); | |
511 | |
512 // Same as above, restricted to the intersection of a memory region and | |
513 // the generation. | |
514 virtual void oop_iterate(MemRegion mr, OopClosure* cl); | |
515 | |
516 // Iterate over all objects in the generation, calling "cl.do_object" on | |
517 // each. | |
518 virtual void object_iterate(ObjectClosure* cl); | |
519 | |
520 // Iterate over all objects allocated in the generation since the last | |
521 // collection, calling "cl.do_object" on each. The generation must have | |
522 // been initialized properly to support this function, or else this call | |
523 // will fail. | |
524 virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0; | |
525 | |
526 // Apply "cl->do_oop" to (the address of) all and only all the ref fields | |
527 // in the current generation that contain pointers to objects in younger | |
528 // generations. Objects allocated since the last "save_marks" call are | |
529 // excluded. | |
530 virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0; | |
531 | |
532 // Inform a generation that it longer contains references to objects | |
533 // in any younger generation. [e.g. Because younger gens are empty, | |
534 // clear the card table.] | |
535 virtual void clear_remembered_set() { } | |
536 | |
537 // Inform a generation that some of its objects have moved. [e.g. The | |
538 // generation's spaces were compacted, invalidating the card table.] | |
539 virtual void invalidate_remembered_set() { } | |
540 | |
541 // Block abstraction. | |
542 | |
543 // Returns the address of the start of the "block" that contains the | |
544 // address "addr". We say "blocks" instead of "object" since some heaps | |
545 // may not pack objects densely; a chunk may either be an object or a | |
546 // non-object. | |
547 virtual HeapWord* block_start(const void* addr) const; | |
548 | |
549 // Requires "addr" to be the start of a chunk, and returns its size. | |
550 // "addr + size" is required to be the start of a new chunk, or the end | |
551 // of the active area of the heap. | |
552 virtual size_t block_size(const HeapWord* addr) const ; | |
553 | |
554 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
555 // the block is an object. | |
556 virtual bool block_is_obj(const HeapWord* addr) const; | |
557 | |
558 | |
559 // PrintGC, PrintGCDetails support | |
560 void print_heap_change(size_t prev_used) const; | |
561 | |
562 // PrintHeapAtGC support | |
563 virtual void print() const; | |
564 virtual void print_on(outputStream* st) const; | |
565 | |
566 virtual void verify(bool allow_dirty) = 0; | |
567 | |
568 struct StatRecord { | |
569 int invocations; | |
570 elapsedTimer accumulated_time; | |
571 StatRecord() : | |
572 invocations(0), | |
573 accumulated_time(elapsedTimer()) {} | |
574 }; | |
575 private: | |
576 StatRecord _stat_record; | |
577 public: | |
578 StatRecord* stat_record() { return &_stat_record; } | |
579 | |
580 virtual void print_summary_info(); | |
581 virtual void print_summary_info_on(outputStream* st); | |
582 | |
583 // Performance Counter support | |
584 virtual void update_counters() = 0; | |
585 virtual CollectorCounters* counters() { return _gc_counters; } | |
586 }; | |
587 | |
588 // Class CardGeneration is a generation that is covered by a card table, | |
589 // and uses a card-size block-offset array to implement block_start. | |
590 | |
591 // class BlockOffsetArray; | |
592 // class BlockOffsetArrayContigSpace; | |
593 class BlockOffsetSharedArray; | |
594 | |
595 class CardGeneration: public Generation { | |
596 friend class VMStructs; | |
597 protected: | |
598 // This is shared with other generations. | |
599 GenRemSet* _rs; | |
600 // This is local to this generation. | |
601 BlockOffsetSharedArray* _bts; | |
602 | |
603 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level, | |
604 GenRemSet* remset); | |
605 | |
606 public: | |
607 | |
608 virtual void clear_remembered_set(); | |
609 | |
610 virtual void invalidate_remembered_set(); | |
611 | |
612 virtual void prepare_for_verify(); | |
613 }; | |
614 | |
615 // OneContigSpaceCardGeneration models a heap of old objects contained in a single | |
616 // contiguous space. | |
617 // | |
618 // Garbage collection is performed using mark-compact. | |
619 | |
620 class OneContigSpaceCardGeneration: public CardGeneration { | |
621 friend class VMStructs; | |
622 // Abstractly, this is a subtype that gets access to protected fields. | |
623 friend class CompactingPermGen; | |
624 friend class VM_PopulateDumpSharedSpace; | |
625 | |
626 protected: | |
627 size_t _min_heap_delta_bytes; // Minimum amount to expand. | |
628 ContiguousSpace* _the_space; // actual space holding objects | |
629 WaterMark _last_gc; // watermark between objects allocated before | |
630 // and after last GC. | |
631 | |
632 // Grow generation with specified size (returns false if unable to grow) | |
633 bool grow_by(size_t bytes); | |
634 // Grow generation to reserved size. | |
635 bool grow_to_reserved(); | |
636 // Shrink generation with specified size (returns false if unable to shrink) | |
637 void shrink_by(size_t bytes); | |
638 | |
639 // Allocation failure | |
640 void expand(size_t bytes, size_t expand_bytes); | |
641 void shrink(size_t bytes); | |
642 | |
643 // Accessing spaces | |
644 ContiguousSpace* the_space() const { return _the_space; } | |
645 | |
646 public: | |
647 OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size, | |
648 size_t min_heap_delta_bytes, | |
649 int level, GenRemSet* remset, | |
650 ContiguousSpace* space) : | |
651 CardGeneration(rs, initial_byte_size, level, remset), | |
652 _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes) | |
653 {} | |
654 | |
655 inline bool is_in(const void* p) const; | |
656 | |
657 // Space enquiries | |
658 size_t capacity() const; | |
659 size_t used() const; | |
660 size_t free() const; | |
661 | |
662 MemRegion used_region() const; | |
663 | |
664 size_t unsafe_max_alloc_nogc() const; | |
665 size_t contiguous_available() const; | |
666 | |
667 // Iteration | |
668 void object_iterate(ObjectClosure* blk); | |
669 void space_iterate(SpaceClosure* blk, bool usedOnly = false); | |
670 void object_iterate_since_last_GC(ObjectClosure* cl); | |
671 | |
672 void younger_refs_iterate(OopsInGenClosure* blk); | |
673 | |
674 inline CompactibleSpace* first_compaction_space() const; | |
675 | |
676 virtual inline HeapWord* allocate(size_t word_size, bool is_tlab); | |
677 virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab); | |
678 | |
679 // Accessing marks | |
680 inline WaterMark top_mark(); | |
681 inline WaterMark bottom_mark(); | |
682 | |
683 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
684 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); | |
685 OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v) | |
686 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL) | |
687 | |
688 void save_marks(); | |
689 void reset_saved_marks(); | |
690 bool no_allocs_since_save_marks(); | |
691 | |
692 inline size_t block_size(const HeapWord* addr) const; | |
693 | |
694 inline bool block_is_obj(const HeapWord* addr) const; | |
695 | |
696 virtual void collect(bool full, | |
697 bool clear_all_soft_refs, | |
698 size_t size, | |
699 bool is_tlab); | |
700 HeapWord* expand_and_allocate(size_t size, | |
701 bool is_tlab, | |
702 bool parallel = false); | |
703 | |
704 virtual void prepare_for_verify(); | |
705 | |
706 virtual void gc_epilogue(bool full); | |
707 | |
708 virtual void verify(bool allow_dirty); | |
709 virtual void print_on(outputStream* st) const; | |
710 }; |