0
|
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 };
|