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annotate src/share/vm/memory/generation.hpp @ 2645:b2c1e959be46
Clean up around BlockBegin / StdEntry.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 11 May 2011 14:34:29 +0200 |
parents | f95d63e2154a |
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0 | 1 /* |
1972 | 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_MEMORY_GENERATION_HPP |
26 #define SHARE_VM_MEMORY_GENERATION_HPP | |
27 | |
28 #include "gc_implementation/shared/collectorCounters.hpp" | |
29 #include "memory/allocation.hpp" | |
30 #include "memory/memRegion.hpp" | |
31 #include "memory/referenceProcessor.hpp" | |
32 #include "memory/universe.hpp" | |
33 #include "memory/watermark.hpp" | |
34 #include "runtime/mutex.hpp" | |
35 #include "runtime/perfData.hpp" | |
36 #include "runtime/virtualspace.hpp" | |
37 | |
0 | 38 // A Generation models a heap area for similarly-aged objects. |
39 // It will contain one ore more spaces holding the actual objects. | |
40 // | |
41 // The Generation class hierarchy: | |
42 // | |
43 // Generation - abstract base class | |
44 // - DefNewGeneration - allocation area (copy collected) | |
45 // - ParNewGeneration - a DefNewGeneration that is collected by | |
46 // several threads | |
47 // - CardGeneration - abstract class adding offset array behavior | |
48 // - OneContigSpaceCardGeneration - abstract class holding a single | |
49 // contiguous space with card marking | |
50 // - TenuredGeneration - tenured (old object) space (markSweepCompact) | |
51 // - CompactingPermGenGen - reflective object area (klasses, methods, symbols, ...) | |
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 + PermGeneration | |
59 // DefNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen | |
60 // | |
61 // ParNewGeneration + TenuredGeneration + PermGeneration | |
62 // ParNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen | |
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 { | |
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 ASParNew, | |
136 ASConcurrentMarkSweep, | |
137 DefNew, | |
138 ParNew, | |
139 MarkSweepCompact, | |
140 ConcurrentMarkSweep, | |
141 Other | |
142 }; | |
143 | |
144 enum SomePublicConstants { | |
145 // Generations are GenGrain-aligned and have size that are multiples of | |
146 // GenGrain. | |
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147 // Note: on ARM we add 1 bit for card_table_base to be properly aligned |
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148 // (we expect its low byte to be zero - see implementation of post_barrier) |
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149 LogOfGenGrain = 16 ARM_ONLY(+1), |
0 | 150 GenGrain = 1 << LogOfGenGrain |
151 }; | |
152 | |
153 // allocate and initialize ("weak") refs processing support | |
154 virtual void ref_processor_init(); | |
155 void set_ref_processor(ReferenceProcessor* rp) { | |
156 assert(_ref_processor == NULL, "clobbering existing _ref_processor"); | |
157 _ref_processor = rp; | |
158 } | |
159 | |
160 virtual Generation::Name kind() { return Generation::Other; } | |
161 GenerationSpec* spec(); | |
162 | |
163 // This properly belongs in the collector, but for now this | |
164 // will do. | |
165 virtual bool refs_discovery_is_atomic() const { return true; } | |
166 virtual bool refs_discovery_is_mt() const { return false; } | |
167 | |
168 // Space enquiries (results in bytes) | |
169 virtual size_t capacity() const = 0; // The maximum number of object bytes the | |
170 // generation can currently hold. | |
171 virtual size_t used() const = 0; // The number of used bytes in the gen. | |
172 virtual size_t free() const = 0; // The number of free bytes in the gen. | |
173 | |
174 // Support for java.lang.Runtime.maxMemory(); see CollectedHeap. | |
175 // Returns the total number of bytes available in a generation | |
176 // for the allocation of objects. | |
177 virtual size_t max_capacity() const; | |
178 | |
179 // If this is a young generation, the maximum number of bytes that can be | |
180 // allocated in this generation before a GC is triggered. | |
181 virtual size_t capacity_before_gc() const { return 0; } | |
182 | |
183 // The largest number of contiguous free bytes in the generation, | |
184 // including expansion (Assumes called at a safepoint.) | |
185 virtual size_t contiguous_available() const = 0; | |
186 // The largest number of contiguous free bytes in this or any higher generation. | |
187 virtual size_t max_contiguous_available() const; | |
188 | |
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189 // Returns true if promotions of the specified amount are |
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190 // likely to succeed without a promotion failure. |
0 | 191 // Promotion of the full amount is not guaranteed but |
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192 // might be attempted in the worst case. |
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193 virtual bool promotion_attempt_is_safe(size_t max_promotion_in_bytes) const; |
0 | 194 |
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195 // For a non-young generation, this interface can be used to inform a |
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196 // generation that a promotion attempt into that generation failed. |
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197 // Typically used to enable diagnostic output for post-mortem analysis, |
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198 // but other uses of the interface are not ruled out. |
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199 virtual void promotion_failure_occurred() { /* does nothing */ } |
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200 |
0 | 201 // Return an estimate of the maximum allocation that could be performed |
202 // in the generation without triggering any collection or expansion | |
203 // activity. It is "unsafe" because no locks are taken; the result | |
204 // should be treated as an approximation, not a guarantee, for use in | |
205 // heuristic resizing decisions. | |
206 virtual size_t unsafe_max_alloc_nogc() const = 0; | |
207 | |
208 // Returns true if this generation cannot be expanded further | |
209 // without a GC. Override as appropriate. | |
210 virtual bool is_maximal_no_gc() const { | |
211 return _virtual_space.uncommitted_size() == 0; | |
212 } | |
213 | |
214 MemRegion reserved() const { return _reserved; } | |
215 | |
216 // Returns a region guaranteed to contain all the objects in the | |
217 // generation. | |
218 virtual MemRegion used_region() const { return _reserved; } | |
219 | |
220 MemRegion prev_used_region() const { return _prev_used_region; } | |
221 virtual void save_used_region() { _prev_used_region = used_region(); } | |
222 | |
223 // Returns "TRUE" iff "p" points into an allocated object in the generation. | |
224 // For some kinds of generations, this may be an expensive operation. | |
225 // To avoid performance problems stemming from its inadvertent use in | |
226 // product jvm's, we restrict its use to assertion checking or | |
227 // verification only. | |
228 virtual bool is_in(const void* p) const; | |
229 | |
230 /* Returns "TRUE" iff "p" points into the reserved area of the generation. */ | |
231 bool is_in_reserved(const void* p) const { | |
232 return _reserved.contains(p); | |
233 } | |
234 | |
235 // Check that the generation kind is DefNewGeneration or a sub | |
236 // class of DefNewGeneration and return a DefNewGeneration* | |
237 DefNewGeneration* as_DefNewGeneration(); | |
238 | |
239 // If some space in the generation contains the given "addr", return a | |
240 // pointer to that space, else return "NULL". | |
241 virtual Space* space_containing(const void* addr) const; | |
242 | |
243 // Iteration - do not use for time critical operations | |
244 virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0; | |
245 | |
246 // Returns the first space, if any, in the generation that can participate | |
247 // in compaction, or else "NULL". | |
248 virtual CompactibleSpace* first_compaction_space() const = 0; | |
249 | |
250 // Returns "true" iff this generation should be used to allocate an | |
251 // object of the given size. Young generations might | |
252 // wish to exclude very large objects, for example, since, if allocated | |
253 // often, they would greatly increase the frequency of young-gen | |
254 // collection. | |
255 virtual bool should_allocate(size_t word_size, bool is_tlab) { | |
256 bool result = false; | |
257 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize); | |
258 if (!is_tlab || supports_tlab_allocation()) { | |
259 result = (word_size > 0) && (word_size < overflow_limit); | |
260 } | |
261 return result; | |
262 } | |
263 | |
264 // Allocate and returns a block of the requested size, or returns "NULL". | |
265 // Assumes the caller has done any necessary locking. | |
266 virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0; | |
267 | |
268 // Like "allocate", but performs any necessary locking internally. | |
269 virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0; | |
270 | |
271 // A 'younger' gen has reached an allocation limit, and uses this to notify | |
272 // the next older gen. The return value is a new limit, or NULL if none. The | |
273 // caller must do the necessary locking. | |
274 virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top, | |
275 size_t word_size) { | |
276 return NULL; | |
277 } | |
278 | |
279 // Some generation may offer a region for shared, contiguous allocation, | |
280 // via inlined code (by exporting the address of the top and end fields | |
281 // defining the extent of the contiguous allocation region.) | |
282 | |
283 // This function returns "true" iff the heap supports this kind of | |
284 // allocation. (More precisely, this means the style of allocation that | |
285 // increments *top_addr()" with a CAS.) (Default is "no".) | |
286 // A generation that supports this allocation style must use lock-free | |
287 // allocation for *all* allocation, since there are times when lock free | |
288 // allocation will be concurrent with plain "allocate" calls. | |
289 virtual bool supports_inline_contig_alloc() const { return false; } | |
290 | |
291 // These functions return the addresses of the fields that define the | |
292 // boundaries of the contiguous allocation area. (These fields should be | |
293 // physicall near to one another.) | |
294 virtual HeapWord** top_addr() const { return NULL; } | |
295 virtual HeapWord** end_addr() const { return NULL; } | |
296 | |
297 // Thread-local allocation buffers | |
298 virtual bool supports_tlab_allocation() const { return false; } | |
299 virtual size_t tlab_capacity() const { | |
300 guarantee(false, "Generation doesn't support thread local allocation buffers"); | |
301 return 0; | |
302 } | |
303 virtual size_t unsafe_max_tlab_alloc() const { | |
304 guarantee(false, "Generation doesn't support thread local allocation buffers"); | |
305 return 0; | |
306 } | |
307 | |
308 // "obj" is the address of an object in a younger generation. Allocate space | |
309 // for "obj" in the current (or some higher) generation, and copy "obj" into | |
310 // the newly allocated space, if possible, returning the result (or NULL if | |
311 // the allocation failed). | |
312 // | |
313 // The "obj_size" argument is just obj->size(), passed along so the caller can | |
314 // avoid repeating the virtual call to retrieve it. | |
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315 virtual oop promote(oop obj, size_t obj_size); |
0 | 316 |
317 // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote | |
318 // object "obj", whose original mark word was "m", and whose size is | |
319 // "word_sz". If possible, allocate space for "obj", copy obj into it | |
320 // (taking care to copy "m" into the mark word when done, since the mark | |
321 // word of "obj" may have been overwritten with a forwarding pointer, and | |
322 // also taking care to copy the klass pointer *last*. Returns the new | |
323 // object if successful, or else NULL. | |
324 virtual oop par_promote(int thread_num, | |
325 oop obj, markOop m, size_t word_sz); | |
326 | |
327 // Undo, if possible, the most recent par_promote_alloc allocation by | |
328 // "thread_num" ("obj", of "word_sz"). | |
329 virtual void par_promote_alloc_undo(int thread_num, | |
330 HeapWord* obj, size_t word_sz); | |
331 | |
332 // Informs the current generation that all par_promote_alloc's in the | |
333 // collection have been completed; any supporting data structures can be | |
334 // reset. Default is to do nothing. | |
335 virtual void par_promote_alloc_done(int thread_num) {} | |
336 | |
337 // Informs the current generation that all oop_since_save_marks_iterates | |
338 // performed by "thread_num" in the current collection, if any, have been | |
339 // completed; any supporting data structures can be reset. Default is to | |
340 // do nothing. | |
341 virtual void par_oop_since_save_marks_iterate_done(int thread_num) {} | |
342 | |
343 // This generation will collect all younger generations | |
344 // during a full collection. | |
345 virtual bool full_collects_younger_generations() const { return false; } | |
346 | |
347 // This generation does in-place marking, meaning that mark words | |
348 // are mutated during the marking phase and presumably reinitialized | |
349 // to a canonical value after the GC. This is currently used by the | |
350 // biased locking implementation to determine whether additional | |
351 // work is required during the GC prologue and epilogue. | |
352 virtual bool performs_in_place_marking() const { return true; } | |
353 | |
354 // Returns "true" iff collect() should subsequently be called on this | |
355 // this generation. See comment below. | |
356 // This is a generic implementation which can be overridden. | |
357 // | |
358 // Note: in the current (1.4) implementation, when genCollectedHeap's | |
359 // incremental_collection_will_fail flag is set, all allocations are | |
360 // slow path (the only fast-path place to allocate is DefNew, which | |
361 // will be full if the flag is set). | |
362 // Thus, older generations which collect younger generations should | |
363 // test this flag and collect if it is set. | |
364 virtual bool should_collect(bool full, | |
365 size_t word_size, | |
366 bool is_tlab) { | |
367 return (full || should_allocate(word_size, is_tlab)); | |
368 } | |
369 | |
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370 // Returns true if the collection is likely to be safely |
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371 // completed. Even if this method returns true, a collection |
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372 // may not be guaranteed to succeed, and the system should be |
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373 // able to safely unwind and recover from that failure, albeit |
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374 // at some additional cost. |
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375 virtual bool collection_attempt_is_safe() { |
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376 guarantee(false, "Are you sure you want to call this method?"); |
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377 return true; |
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378 } |
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379 |
0 | 380 // Perform a garbage collection. |
381 // If full is true attempt a full garbage collection of this generation. | |
382 // Otherwise, attempting to (at least) free enough space to support an | |
383 // allocation of the given "word_size". | |
384 virtual void collect(bool full, | |
385 bool clear_all_soft_refs, | |
386 size_t word_size, | |
387 bool is_tlab) = 0; | |
388 | |
389 // Perform a heap collection, attempting to create (at least) enough | |
390 // space to support an allocation of the given "word_size". If | |
391 // successful, perform the allocation and return the resulting | |
392 // "oop" (initializing the allocated block). If the allocation is | |
393 // still unsuccessful, return "NULL". | |
394 virtual HeapWord* expand_and_allocate(size_t word_size, | |
395 bool is_tlab, | |
396 bool parallel = false) = 0; | |
397 | |
398 // Some generations may require some cleanup or preparation actions before | |
399 // allowing a collection. The default is to do nothing. | |
400 virtual void gc_prologue(bool full) {}; | |
401 | |
402 // Some generations may require some cleanup actions after a collection. | |
403 // The default is to do nothing. | |
404 virtual void gc_epilogue(bool full) {}; | |
405 | |
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406 // Save the high water marks for the used space in a generation. |
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407 virtual void record_spaces_top() {}; |
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408 |
0 | 409 // Some generations may need to be "fixed-up" after some allocation |
410 // activity to make them parsable again. The default is to do nothing. | |
411 virtual void ensure_parsability() {}; | |
412 | |
413 // Time (in ms) when we were last collected or now if a collection is | |
414 // in progress. | |
415 virtual jlong time_of_last_gc(jlong now) { | |
416 // XXX See note in genCollectedHeap::millis_since_last_gc() | |
417 NOT_PRODUCT( | |
418 if (now < _time_of_last_gc) { | |
419 warning("time warp: %d to %d", _time_of_last_gc, now); | |
420 } | |
421 ) | |
422 return _time_of_last_gc; | |
423 } | |
424 | |
425 virtual void update_time_of_last_gc(jlong now) { | |
426 _time_of_last_gc = now; | |
427 } | |
428 | |
429 // Generations may keep statistics about collection. This | |
430 // method updates those statistics. current_level is | |
431 // the level of the collection that has most recently | |
432 // occurred. This allows the generation to decide what | |
433 // statistics are valid to collect. For example, the | |
434 // generation can decide to gather the amount of promoted data | |
435 // if the collection of the younger generations has completed. | |
436 GCStats* gc_stats() const { return _gc_stats; } | |
437 virtual void update_gc_stats(int current_level, bool full) {} | |
438 | |
439 // Mark sweep support phase2 | |
440 virtual void prepare_for_compaction(CompactPoint* cp); | |
441 // Mark sweep support phase3 | |
442 virtual void pre_adjust_pointers() {ShouldNotReachHere();} | |
443 virtual void adjust_pointers(); | |
444 // Mark sweep support phase4 | |
445 virtual void compact(); | |
446 virtual void post_compact() {ShouldNotReachHere();} | |
447 | |
448 // Support for CMS's rescan. In this general form we return a pointer | |
449 // to an abstract object that can be used, based on specific previously | |
450 // decided protocols, to exchange information between generations, | |
451 // information that may be useful for speeding up certain types of | |
452 // garbage collectors. A NULL value indicates to the client that | |
453 // no data recording is expected by the provider. The data-recorder is | |
454 // expected to be GC worker thread-local, with the worker index | |
455 // indicated by "thr_num". | |
456 virtual void* get_data_recorder(int thr_num) { return NULL; } | |
457 | |
458 // Some generations may require some cleanup actions before allowing | |
459 // a verification. | |
460 virtual void prepare_for_verify() {}; | |
461 | |
462 // Accessing "marks". | |
463 | |
464 // This function gives a generation a chance to note a point between | |
465 // collections. For example, a contiguous generation might note the | |
466 // beginning allocation point post-collection, which might allow some later | |
467 // operations to be optimized. | |
468 virtual void save_marks() {} | |
469 | |
470 // This function allows generations to initialize any "saved marks". That | |
471 // is, should only be called when the generation is empty. | |
472 virtual void reset_saved_marks() {} | |
473 | |
474 // This function is "true" iff any no allocations have occurred in the | |
475 // generation since the last call to "save_marks". | |
476 virtual bool no_allocs_since_save_marks() = 0; | |
477 | |
478 // Apply "cl->apply" to (the addresses of) all reference fields in objects | |
479 // allocated in the current generation since the last call to "save_marks". | |
480 // If more objects are allocated in this generation as a result of applying | |
481 // the closure, iterates over reference fields in those objects as well. | |
482 // Calls "save_marks" at the end of the iteration. | |
483 // General signature... | |
484 virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0; | |
485 // ...and specializations for de-virtualization. (The general | |
486 // implemention of the _nv versions call the virtual version. | |
487 // Note that the _nv suffix is not really semantically necessary, | |
488 // but it avoids some not-so-useful warnings on Solaris.) | |
489 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
490 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
491 oop_since_save_marks_iterate_v((OopsInGenClosure*)cl); \ | |
492 } | |
493 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL) | |
494 | |
495 #undef Generation_SINCE_SAVE_MARKS_DECL | |
496 | |
497 // The "requestor" generation is performing some garbage collection | |
498 // action for which it would be useful to have scratch space. If | |
499 // the target is not the requestor, no gc actions will be required | |
500 // of the target. The requestor promises to allocate no more than | |
501 // "max_alloc_words" in the target generation (via promotion say, | |
502 // if the requestor is a young generation and the target is older). | |
503 // If the target generation can provide any scratch space, it adds | |
504 // it to "list", leaving "list" pointing to the head of the | |
505 // augmented list. The default is to offer no space. | |
506 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, | |
507 size_t max_alloc_words) {} | |
508 | |
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509 // Give each generation an opportunity to do clean up for any |
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510 // contributed scratch. |
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511 virtual void reset_scratch() {}; |
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512 |
0 | 513 // When an older generation has been collected, and perhaps resized, |
514 // this method will be invoked on all younger generations (from older to | |
515 // younger), allowing them to resize themselves as appropriate. | |
516 virtual void compute_new_size() = 0; | |
517 | |
518 // Printing | |
519 virtual const char* name() const = 0; | |
520 virtual const char* short_name() const = 0; | |
521 | |
522 int level() const { return _level; } | |
523 | |
524 // Attributes | |
525 | |
526 // True iff the given generation may only be the youngest generation. | |
527 virtual bool must_be_youngest() const = 0; | |
528 // True iff the given generation may only be the oldest generation. | |
529 virtual bool must_be_oldest() const = 0; | |
530 | |
531 // Reference Processing accessor | |
532 ReferenceProcessor* const ref_processor() { return _ref_processor; } | |
533 | |
534 // Iteration. | |
535 | |
536 // Iterate over all the ref-containing fields of all objects in the | |
537 // generation, calling "cl.do_oop" on each. | |
538 virtual void oop_iterate(OopClosure* cl); | |
539 | |
540 // Same as above, restricted to the intersection of a memory region and | |
541 // the generation. | |
542 virtual void oop_iterate(MemRegion mr, OopClosure* cl); | |
543 | |
544 // Iterate over all objects in the generation, calling "cl.do_object" on | |
545 // each. | |
546 virtual void object_iterate(ObjectClosure* cl); | |
547 | |
517
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548 // Iterate over all safe objects in the generation, calling "cl.do_object" on |
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549 // each. An object is safe if its references point to other objects in |
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550 // the heap. This defaults to object_iterate() unless overridden. |
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551 virtual void safe_object_iterate(ObjectClosure* cl); |
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552 |
0 | 553 // Iterate over all objects allocated in the generation since the last |
554 // collection, calling "cl.do_object" on each. The generation must have | |
555 // been initialized properly to support this function, or else this call | |
556 // will fail. | |
557 virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0; | |
558 | |
559 // Apply "cl->do_oop" to (the address of) all and only all the ref fields | |
560 // in the current generation that contain pointers to objects in younger | |
561 // generations. Objects allocated since the last "save_marks" call are | |
562 // excluded. | |
563 virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0; | |
564 | |
565 // Inform a generation that it longer contains references to objects | |
566 // in any younger generation. [e.g. Because younger gens are empty, | |
567 // clear the card table.] | |
568 virtual void clear_remembered_set() { } | |
569 | |
570 // Inform a generation that some of its objects have moved. [e.g. The | |
571 // generation's spaces were compacted, invalidating the card table.] | |
572 virtual void invalidate_remembered_set() { } | |
573 | |
574 // Block abstraction. | |
575 | |
576 // Returns the address of the start of the "block" that contains the | |
577 // address "addr". We say "blocks" instead of "object" since some heaps | |
578 // may not pack objects densely; a chunk may either be an object or a | |
579 // non-object. | |
580 virtual HeapWord* block_start(const void* addr) const; | |
581 | |
582 // Requires "addr" to be the start of a chunk, and returns its size. | |
583 // "addr + size" is required to be the start of a new chunk, or the end | |
584 // of the active area of the heap. | |
585 virtual size_t block_size(const HeapWord* addr) const ; | |
586 | |
587 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
588 // the block is an object. | |
589 virtual bool block_is_obj(const HeapWord* addr) const; | |
590 | |
591 | |
592 // PrintGC, PrintGCDetails support | |
593 void print_heap_change(size_t prev_used) const; | |
594 | |
595 // PrintHeapAtGC support | |
596 virtual void print() const; | |
597 virtual void print_on(outputStream* st) const; | |
598 | |
599 virtual void verify(bool allow_dirty) = 0; | |
600 | |
601 struct StatRecord { | |
602 int invocations; | |
603 elapsedTimer accumulated_time; | |
604 StatRecord() : | |
605 invocations(0), | |
606 accumulated_time(elapsedTimer()) {} | |
607 }; | |
608 private: | |
609 StatRecord _stat_record; | |
610 public: | |
611 StatRecord* stat_record() { return &_stat_record; } | |
612 | |
613 virtual void print_summary_info(); | |
614 virtual void print_summary_info_on(outputStream* st); | |
615 | |
616 // Performance Counter support | |
617 virtual void update_counters() = 0; | |
618 virtual CollectorCounters* counters() { return _gc_counters; } | |
619 }; | |
620 | |
621 // Class CardGeneration is a generation that is covered by a card table, | |
622 // and uses a card-size block-offset array to implement block_start. | |
623 | |
624 // class BlockOffsetArray; | |
625 // class BlockOffsetArrayContigSpace; | |
626 class BlockOffsetSharedArray; | |
627 | |
628 class CardGeneration: public Generation { | |
629 friend class VMStructs; | |
630 protected: | |
631 // This is shared with other generations. | |
632 GenRemSet* _rs; | |
633 // This is local to this generation. | |
634 BlockOffsetSharedArray* _bts; | |
635 | |
636 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level, | |
637 GenRemSet* remset); | |
638 | |
639 public: | |
640 | |
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641 // Attempt to expand the generation by "bytes". Expand by at a |
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642 // minimum "expand_bytes". Return true if some amount (not |
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643 // necessarily the full "bytes") was done. |
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644 virtual bool expand(size_t bytes, size_t expand_bytes); |
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645 |
0 | 646 virtual void clear_remembered_set(); |
647 | |
648 virtual void invalidate_remembered_set(); | |
649 | |
650 virtual void prepare_for_verify(); | |
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651 |
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652 // Grow generation with specified size (returns false if unable to grow) |
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653 virtual bool grow_by(size_t bytes) = 0; |
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654 // Grow generation to reserved size. |
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655 virtual bool grow_to_reserved() = 0; |
0 | 656 }; |
657 | |
658 // OneContigSpaceCardGeneration models a heap of old objects contained in a single | |
659 // contiguous space. | |
660 // | |
661 // Garbage collection is performed using mark-compact. | |
662 | |
663 class OneContigSpaceCardGeneration: public CardGeneration { | |
664 friend class VMStructs; | |
665 // Abstractly, this is a subtype that gets access to protected fields. | |
666 friend class CompactingPermGen; | |
667 friend class VM_PopulateDumpSharedSpace; | |
668 | |
669 protected: | |
670 size_t _min_heap_delta_bytes; // Minimum amount to expand. | |
671 ContiguousSpace* _the_space; // actual space holding objects | |
672 WaterMark _last_gc; // watermark between objects allocated before | |
673 // and after last GC. | |
674 | |
675 // Grow generation with specified size (returns false if unable to grow) | |
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676 virtual bool grow_by(size_t bytes); |
0 | 677 // Grow generation to reserved size. |
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678 virtual bool grow_to_reserved(); |
0 | 679 // Shrink generation with specified size (returns false if unable to shrink) |
680 void shrink_by(size_t bytes); | |
681 | |
682 // Allocation failure | |
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683 virtual bool expand(size_t bytes, size_t expand_bytes); |
0 | 684 void shrink(size_t bytes); |
685 | |
686 // Accessing spaces | |
687 ContiguousSpace* the_space() const { return _the_space; } | |
688 | |
689 public: | |
690 OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size, | |
691 size_t min_heap_delta_bytes, | |
692 int level, GenRemSet* remset, | |
693 ContiguousSpace* space) : | |
694 CardGeneration(rs, initial_byte_size, level, remset), | |
695 _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes) | |
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 void object_iterate_since_last_GC(ObjectClosure* cl); | |
714 | |
715 void younger_refs_iterate(OopsInGenClosure* blk); | |
716 | |
717 inline CompactibleSpace* first_compaction_space() const; | |
718 | |
719 virtual inline HeapWord* allocate(size_t word_size, bool is_tlab); | |
720 virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab); | |
721 | |
722 // Accessing marks | |
723 inline WaterMark top_mark(); | |
724 inline WaterMark bottom_mark(); | |
725 | |
726 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
727 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); | |
728 OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v) | |
729 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL) | |
730 | |
731 void save_marks(); | |
732 void reset_saved_marks(); | |
733 bool no_allocs_since_save_marks(); | |
734 | |
735 inline size_t block_size(const HeapWord* addr) const; | |
736 | |
737 inline bool block_is_obj(const HeapWord* addr) const; | |
738 | |
739 virtual void collect(bool full, | |
740 bool clear_all_soft_refs, | |
741 size_t size, | |
742 bool is_tlab); | |
743 HeapWord* expand_and_allocate(size_t size, | |
744 bool is_tlab, | |
745 bool parallel = false); | |
746 | |
747 virtual void prepare_for_verify(); | |
748 | |
749 virtual void gc_epilogue(bool full); | |
750 | |
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751 virtual void record_spaces_top(); |
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752 |
0 | 753 virtual void verify(bool allow_dirty); |
754 virtual void print_on(outputStream* st) const; | |
755 }; | |
1972 | 756 |
757 #endif // SHARE_VM_MEMORY_GENERATION_HPP |