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annotate src/share/vm/memory/generation.hpp @ 1552:c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair
| author | trims |
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| date | Thu, 27 May 2010 19:08:38 -0700 |
| parents | e018e6884bd8 |
| children | 126ea7725993 |
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| 0 | 1 /* |
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2 * Copyright (c) 1997, 2009, 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 | |
| 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 | |
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184 // For a non-young generation, this interface can be used to inform a |
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185 // generation that a promotion attempt into that generation failed. |
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186 // Typically used to enable diagnostic output for post-mortem analysis, |
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187 // but other uses of the interface are not ruled out. |
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188 virtual void promotion_failure_occurred() { /* does nothing */ } |
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189 |
| 0 | 190 // Return an estimate of the maximum allocation that could be performed |
| 191 // in the generation without triggering any collection or expansion | |
| 192 // activity. It is "unsafe" because no locks are taken; the result | |
| 193 // should be treated as an approximation, not a guarantee, for use in | |
| 194 // heuristic resizing decisions. | |
| 195 virtual size_t unsafe_max_alloc_nogc() const = 0; | |
| 196 | |
| 197 // Returns true if this generation cannot be expanded further | |
| 198 // without a GC. Override as appropriate. | |
| 199 virtual bool is_maximal_no_gc() const { | |
| 200 return _virtual_space.uncommitted_size() == 0; | |
| 201 } | |
| 202 | |
| 203 MemRegion reserved() const { return _reserved; } | |
| 204 | |
| 205 // Returns a region guaranteed to contain all the objects in the | |
| 206 // generation. | |
| 207 virtual MemRegion used_region() const { return _reserved; } | |
| 208 | |
| 209 MemRegion prev_used_region() const { return _prev_used_region; } | |
| 210 virtual void save_used_region() { _prev_used_region = used_region(); } | |
| 211 | |
| 212 // Returns "TRUE" iff "p" points into an allocated object in the generation. | |
| 213 // For some kinds of generations, this may be an expensive operation. | |
| 214 // To avoid performance problems stemming from its inadvertent use in | |
| 215 // product jvm's, we restrict its use to assertion checking or | |
| 216 // verification only. | |
| 217 virtual bool is_in(const void* p) const; | |
| 218 | |
| 219 /* Returns "TRUE" iff "p" points into the reserved area of the generation. */ | |
| 220 bool is_in_reserved(const void* p) const { | |
| 221 return _reserved.contains(p); | |
| 222 } | |
| 223 | |
| 224 // Check that the generation kind is DefNewGeneration or a sub | |
| 225 // class of DefNewGeneration and return a DefNewGeneration* | |
| 226 DefNewGeneration* as_DefNewGeneration(); | |
| 227 | |
| 228 // If some space in the generation contains the given "addr", return a | |
| 229 // pointer to that space, else return "NULL". | |
| 230 virtual Space* space_containing(const void* addr) const; | |
| 231 | |
| 232 // Iteration - do not use for time critical operations | |
| 233 virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0; | |
| 234 | |
| 235 // Returns the first space, if any, in the generation that can participate | |
| 236 // in compaction, or else "NULL". | |
| 237 virtual CompactibleSpace* first_compaction_space() const = 0; | |
| 238 | |
| 239 // Returns "true" iff this generation should be used to allocate an | |
| 240 // object of the given size. Young generations might | |
| 241 // wish to exclude very large objects, for example, since, if allocated | |
| 242 // often, they would greatly increase the frequency of young-gen | |
| 243 // collection. | |
| 244 virtual bool should_allocate(size_t word_size, bool is_tlab) { | |
| 245 bool result = false; | |
| 246 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize); | |
| 247 if (!is_tlab || supports_tlab_allocation()) { | |
| 248 result = (word_size > 0) && (word_size < overflow_limit); | |
| 249 } | |
| 250 return result; | |
| 251 } | |
| 252 | |
| 253 // Allocate and returns a block of the requested size, or returns "NULL". | |
| 254 // Assumes the caller has done any necessary locking. | |
| 255 virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0; | |
| 256 | |
| 257 // Like "allocate", but performs any necessary locking internally. | |
| 258 virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0; | |
| 259 | |
| 260 // A 'younger' gen has reached an allocation limit, and uses this to notify | |
| 261 // the next older gen. The return value is a new limit, or NULL if none. The | |
| 262 // caller must do the necessary locking. | |
| 263 virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top, | |
| 264 size_t word_size) { | |
| 265 return NULL; | |
| 266 } | |
| 267 | |
| 268 // Some generation may offer a region for shared, contiguous allocation, | |
| 269 // via inlined code (by exporting the address of the top and end fields | |
| 270 // defining the extent of the contiguous allocation region.) | |
| 271 | |
| 272 // This function returns "true" iff the heap supports this kind of | |
| 273 // allocation. (More precisely, this means the style of allocation that | |
| 274 // increments *top_addr()" with a CAS.) (Default is "no".) | |
| 275 // A generation that supports this allocation style must use lock-free | |
| 276 // allocation for *all* allocation, since there are times when lock free | |
| 277 // allocation will be concurrent with plain "allocate" calls. | |
| 278 virtual bool supports_inline_contig_alloc() const { return false; } | |
| 279 | |
| 280 // These functions return the addresses of the fields that define the | |
| 281 // boundaries of the contiguous allocation area. (These fields should be | |
| 282 // physicall near to one another.) | |
| 283 virtual HeapWord** top_addr() const { return NULL; } | |
| 284 virtual HeapWord** end_addr() const { return NULL; } | |
| 285 | |
| 286 // Thread-local allocation buffers | |
| 287 virtual bool supports_tlab_allocation() const { return false; } | |
| 288 virtual size_t tlab_capacity() const { | |
| 289 guarantee(false, "Generation doesn't support thread local allocation buffers"); | |
| 290 return 0; | |
| 291 } | |
| 292 virtual size_t unsafe_max_tlab_alloc() const { | |
| 293 guarantee(false, "Generation doesn't support thread local allocation buffers"); | |
| 294 return 0; | |
| 295 } | |
| 296 | |
| 297 // "obj" is the address of an object in a younger generation. Allocate space | |
| 298 // for "obj" in the current (or some higher) generation, and copy "obj" into | |
| 299 // the newly allocated space, if possible, returning the result (or NULL if | |
| 300 // the allocation failed). | |
| 301 // | |
| 302 // The "obj_size" argument is just obj->size(), passed along so the caller can | |
| 303 // avoid repeating the virtual call to retrieve it. | |
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304 virtual oop promote(oop obj, size_t obj_size); |
| 0 | 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 | |
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385 // Save the high water marks for the used space in a generation. |
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386 virtual void record_spaces_top() {}; |
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387 |
| 0 | 388 // Some generations may need to be "fixed-up" after some allocation |
| 389 // activity to make them parsable again. The default is to do nothing. | |
| 390 virtual void ensure_parsability() {}; | |
| 391 | |
| 392 // Time (in ms) when we were last collected or now if a collection is | |
| 393 // in progress. | |
| 394 virtual jlong time_of_last_gc(jlong now) { | |
| 395 // XXX See note in genCollectedHeap::millis_since_last_gc() | |
| 396 NOT_PRODUCT( | |
| 397 if (now < _time_of_last_gc) { | |
| 398 warning("time warp: %d to %d", _time_of_last_gc, now); | |
| 399 } | |
| 400 ) | |
| 401 return _time_of_last_gc; | |
| 402 } | |
| 403 | |
| 404 virtual void update_time_of_last_gc(jlong now) { | |
| 405 _time_of_last_gc = now; | |
| 406 } | |
| 407 | |
| 408 // Generations may keep statistics about collection. This | |
| 409 // method updates those statistics. current_level is | |
| 410 // the level of the collection that has most recently | |
| 411 // occurred. This allows the generation to decide what | |
| 412 // statistics are valid to collect. For example, the | |
| 413 // generation can decide to gather the amount of promoted data | |
| 414 // if the collection of the younger generations has completed. | |
| 415 GCStats* gc_stats() const { return _gc_stats; } | |
| 416 virtual void update_gc_stats(int current_level, bool full) {} | |
| 417 | |
| 418 // Mark sweep support phase2 | |
| 419 virtual void prepare_for_compaction(CompactPoint* cp); | |
| 420 // Mark sweep support phase3 | |
| 421 virtual void pre_adjust_pointers() {ShouldNotReachHere();} | |
| 422 virtual void adjust_pointers(); | |
| 423 // Mark sweep support phase4 | |
| 424 virtual void compact(); | |
| 425 virtual void post_compact() {ShouldNotReachHere();} | |
| 426 | |
| 427 // Support for CMS's rescan. In this general form we return a pointer | |
| 428 // to an abstract object that can be used, based on specific previously | |
| 429 // decided protocols, to exchange information between generations, | |
| 430 // information that may be useful for speeding up certain types of | |
| 431 // garbage collectors. A NULL value indicates to the client that | |
| 432 // no data recording is expected by the provider. The data-recorder is | |
| 433 // expected to be GC worker thread-local, with the worker index | |
| 434 // indicated by "thr_num". | |
| 435 virtual void* get_data_recorder(int thr_num) { return NULL; } | |
| 436 | |
| 437 // Some generations may require some cleanup actions before allowing | |
| 438 // a verification. | |
| 439 virtual void prepare_for_verify() {}; | |
| 440 | |
| 441 // Accessing "marks". | |
| 442 | |
| 443 // This function gives a generation a chance to note a point between | |
| 444 // collections. For example, a contiguous generation might note the | |
| 445 // beginning allocation point post-collection, which might allow some later | |
| 446 // operations to be optimized. | |
| 447 virtual void save_marks() {} | |
| 448 | |
| 449 // This function allows generations to initialize any "saved marks". That | |
| 450 // is, should only be called when the generation is empty. | |
| 451 virtual void reset_saved_marks() {} | |
| 452 | |
| 453 // This function is "true" iff any no allocations have occurred in the | |
| 454 // generation since the last call to "save_marks". | |
| 455 virtual bool no_allocs_since_save_marks() = 0; | |
| 456 | |
| 457 // Apply "cl->apply" to (the addresses of) all reference fields in objects | |
| 458 // allocated in the current generation since the last call to "save_marks". | |
| 459 // If more objects are allocated in this generation as a result of applying | |
| 460 // the closure, iterates over reference fields in those objects as well. | |
| 461 // Calls "save_marks" at the end of the iteration. | |
| 462 // General signature... | |
| 463 virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0; | |
| 464 // ...and specializations for de-virtualization. (The general | |
| 465 // implemention of the _nv versions call the virtual version. | |
| 466 // Note that the _nv suffix is not really semantically necessary, | |
| 467 // but it avoids some not-so-useful warnings on Solaris.) | |
| 468 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
| 469 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 470 oop_since_save_marks_iterate_v((OopsInGenClosure*)cl); \ | |
| 471 } | |
| 472 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL) | |
| 473 | |
| 474 #undef Generation_SINCE_SAVE_MARKS_DECL | |
| 475 | |
| 476 // The "requestor" generation is performing some garbage collection | |
| 477 // action for which it would be useful to have scratch space. If | |
| 478 // the target is not the requestor, no gc actions will be required | |
| 479 // of the target. The requestor promises to allocate no more than | |
| 480 // "max_alloc_words" in the target generation (via promotion say, | |
| 481 // if the requestor is a young generation and the target is older). | |
| 482 // If the target generation can provide any scratch space, it adds | |
| 483 // it to "list", leaving "list" pointing to the head of the | |
| 484 // augmented list. The default is to offer no space. | |
| 485 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, | |
| 486 size_t max_alloc_words) {} | |
| 487 | |
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488 // Give each generation an opportunity to do clean up for any |
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489 // contributed scratch. |
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490 virtual void reset_scratch() {}; |
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491 |
| 0 | 492 // When an older generation has been collected, and perhaps resized, |
| 493 // this method will be invoked on all younger generations (from older to | |
| 494 // younger), allowing them to resize themselves as appropriate. | |
| 495 virtual void compute_new_size() = 0; | |
| 496 | |
| 497 // Printing | |
| 498 virtual const char* name() const = 0; | |
| 499 virtual const char* short_name() const = 0; | |
| 500 | |
| 501 int level() const { return _level; } | |
| 502 | |
| 503 // Attributes | |
| 504 | |
| 505 // True iff the given generation may only be the youngest generation. | |
| 506 virtual bool must_be_youngest() const = 0; | |
| 507 // True iff the given generation may only be the oldest generation. | |
| 508 virtual bool must_be_oldest() const = 0; | |
| 509 | |
| 510 // Reference Processing accessor | |
| 511 ReferenceProcessor* const ref_processor() { return _ref_processor; } | |
| 512 | |
| 513 // Iteration. | |
| 514 | |
| 515 // Iterate over all the ref-containing fields of all objects in the | |
| 516 // generation, calling "cl.do_oop" on each. | |
| 517 virtual void oop_iterate(OopClosure* cl); | |
| 518 | |
| 519 // Same as above, restricted to the intersection of a memory region and | |
| 520 // the generation. | |
| 521 virtual void oop_iterate(MemRegion mr, OopClosure* cl); | |
| 522 | |
| 523 // Iterate over all objects in the generation, calling "cl.do_object" on | |
| 524 // each. | |
| 525 virtual void object_iterate(ObjectClosure* cl); | |
| 526 | |
|
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527 // Iterate over all safe objects in the generation, calling "cl.do_object" on |
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528 // each. An object is safe if its references point to other objects in |
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529 // the heap. This defaults to object_iterate() unless overridden. |
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530 virtual void safe_object_iterate(ObjectClosure* cl); |
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531 |
| 0 | 532 // Iterate over all objects allocated in the generation since the last |
| 533 // collection, calling "cl.do_object" on each. The generation must have | |
| 534 // been initialized properly to support this function, or else this call | |
| 535 // will fail. | |
| 536 virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0; | |
| 537 | |
| 538 // Apply "cl->do_oop" to (the address of) all and only all the ref fields | |
| 539 // in the current generation that contain pointers to objects in younger | |
| 540 // generations. Objects allocated since the last "save_marks" call are | |
| 541 // excluded. | |
| 542 virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0; | |
| 543 | |
| 544 // Inform a generation that it longer contains references to objects | |
| 545 // in any younger generation. [e.g. Because younger gens are empty, | |
| 546 // clear the card table.] | |
| 547 virtual void clear_remembered_set() { } | |
| 548 | |
| 549 // Inform a generation that some of its objects have moved. [e.g. The | |
| 550 // generation's spaces were compacted, invalidating the card table.] | |
| 551 virtual void invalidate_remembered_set() { } | |
| 552 | |
| 553 // Block abstraction. | |
| 554 | |
| 555 // Returns the address of the start of the "block" that contains the | |
| 556 // address "addr". We say "blocks" instead of "object" since some heaps | |
| 557 // may not pack objects densely; a chunk may either be an object or a | |
| 558 // non-object. | |
| 559 virtual HeapWord* block_start(const void* addr) const; | |
| 560 | |
| 561 // Requires "addr" to be the start of a chunk, and returns its size. | |
| 562 // "addr + size" is required to be the start of a new chunk, or the end | |
| 563 // of the active area of the heap. | |
| 564 virtual size_t block_size(const HeapWord* addr) const ; | |
| 565 | |
| 566 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
| 567 // the block is an object. | |
| 568 virtual bool block_is_obj(const HeapWord* addr) const; | |
| 569 | |
| 570 | |
| 571 // PrintGC, PrintGCDetails support | |
| 572 void print_heap_change(size_t prev_used) const; | |
| 573 | |
| 574 // PrintHeapAtGC support | |
| 575 virtual void print() const; | |
| 576 virtual void print_on(outputStream* st) const; | |
| 577 | |
| 578 virtual void verify(bool allow_dirty) = 0; | |
| 579 | |
| 580 struct StatRecord { | |
| 581 int invocations; | |
| 582 elapsedTimer accumulated_time; | |
| 583 StatRecord() : | |
| 584 invocations(0), | |
| 585 accumulated_time(elapsedTimer()) {} | |
| 586 }; | |
| 587 private: | |
| 588 StatRecord _stat_record; | |
| 589 public: | |
| 590 StatRecord* stat_record() { return &_stat_record; } | |
| 591 | |
| 592 virtual void print_summary_info(); | |
| 593 virtual void print_summary_info_on(outputStream* st); | |
| 594 | |
| 595 // Performance Counter support | |
| 596 virtual void update_counters() = 0; | |
| 597 virtual CollectorCounters* counters() { return _gc_counters; } | |
| 598 }; | |
| 599 | |
| 600 // Class CardGeneration is a generation that is covered by a card table, | |
| 601 // and uses a card-size block-offset array to implement block_start. | |
| 602 | |
| 603 // class BlockOffsetArray; | |
| 604 // class BlockOffsetArrayContigSpace; | |
| 605 class BlockOffsetSharedArray; | |
| 606 | |
| 607 class CardGeneration: public Generation { | |
| 608 friend class VMStructs; | |
| 609 protected: | |
| 610 // This is shared with other generations. | |
| 611 GenRemSet* _rs; | |
| 612 // This is local to this generation. | |
| 613 BlockOffsetSharedArray* _bts; | |
| 614 | |
| 615 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level, | |
| 616 GenRemSet* remset); | |
| 617 | |
| 618 public: | |
| 619 | |
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620 // Attempt to expand the generation by "bytes". Expand by at a |
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621 // minimum "expand_bytes". Return true if some amount (not |
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622 // necessarily the full "bytes") was done. |
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623 virtual bool expand(size_t bytes, size_t expand_bytes); |
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624 |
| 0 | 625 virtual void clear_remembered_set(); |
| 626 | |
| 627 virtual void invalidate_remembered_set(); | |
| 628 | |
| 629 virtual void prepare_for_verify(); | |
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630 |
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631 // Grow generation with specified size (returns false if unable to grow) |
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632 virtual bool grow_by(size_t bytes) = 0; |
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633 // Grow generation to reserved size. |
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634 virtual bool grow_to_reserved() = 0; |
| 0 | 635 }; |
| 636 | |
| 637 // OneContigSpaceCardGeneration models a heap of old objects contained in a single | |
| 638 // contiguous space. | |
| 639 // | |
| 640 // Garbage collection is performed using mark-compact. | |
| 641 | |
| 642 class OneContigSpaceCardGeneration: public CardGeneration { | |
| 643 friend class VMStructs; | |
| 644 // Abstractly, this is a subtype that gets access to protected fields. | |
| 645 friend class CompactingPermGen; | |
| 646 friend class VM_PopulateDumpSharedSpace; | |
| 647 | |
| 648 protected: | |
| 649 size_t _min_heap_delta_bytes; // Minimum amount to expand. | |
| 650 ContiguousSpace* _the_space; // actual space holding objects | |
| 651 WaterMark _last_gc; // watermark between objects allocated before | |
| 652 // and after last GC. | |
| 653 | |
| 654 // Grow generation with specified size (returns false if unable to grow) | |
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655 virtual bool grow_by(size_t bytes); |
| 0 | 656 // Grow generation to reserved size. |
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657 virtual bool grow_to_reserved(); |
| 0 | 658 // Shrink generation with specified size (returns false if unable to shrink) |
| 659 void shrink_by(size_t bytes); | |
| 660 | |
| 661 // Allocation failure | |
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662 virtual bool expand(size_t bytes, size_t expand_bytes); |
| 0 | 663 void shrink(size_t bytes); |
| 664 | |
| 665 // Accessing spaces | |
| 666 ContiguousSpace* the_space() const { return _the_space; } | |
| 667 | |
| 668 public: | |
| 669 OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size, | |
| 670 size_t min_heap_delta_bytes, | |
| 671 int level, GenRemSet* remset, | |
| 672 ContiguousSpace* space) : | |
| 673 CardGeneration(rs, initial_byte_size, level, remset), | |
| 674 _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes) | |
| 675 {} | |
| 676 | |
| 677 inline bool is_in(const void* p) const; | |
| 678 | |
| 679 // Space enquiries | |
| 680 size_t capacity() const; | |
| 681 size_t used() const; | |
| 682 size_t free() const; | |
| 683 | |
| 684 MemRegion used_region() const; | |
| 685 | |
| 686 size_t unsafe_max_alloc_nogc() const; | |
| 687 size_t contiguous_available() const; | |
| 688 | |
| 689 // Iteration | |
| 690 void object_iterate(ObjectClosure* blk); | |
| 691 void space_iterate(SpaceClosure* blk, bool usedOnly = false); | |
| 692 void object_iterate_since_last_GC(ObjectClosure* cl); | |
| 693 | |
| 694 void younger_refs_iterate(OopsInGenClosure* blk); | |
| 695 | |
| 696 inline CompactibleSpace* first_compaction_space() const; | |
| 697 | |
| 698 virtual inline HeapWord* allocate(size_t word_size, bool is_tlab); | |
| 699 virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab); | |
| 700 | |
| 701 // Accessing marks | |
| 702 inline WaterMark top_mark(); | |
| 703 inline WaterMark bottom_mark(); | |
| 704 | |
| 705 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
| 706 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); | |
| 707 OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v) | |
| 708 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL) | |
| 709 | |
| 710 void save_marks(); | |
| 711 void reset_saved_marks(); | |
| 712 bool no_allocs_since_save_marks(); | |
| 713 | |
| 714 inline size_t block_size(const HeapWord* addr) const; | |
| 715 | |
| 716 inline bool block_is_obj(const HeapWord* addr) const; | |
| 717 | |
| 718 virtual void collect(bool full, | |
| 719 bool clear_all_soft_refs, | |
| 720 size_t size, | |
| 721 bool is_tlab); | |
| 722 HeapWord* expand_and_allocate(size_t size, | |
| 723 bool is_tlab, | |
| 724 bool parallel = false); | |
| 725 | |
| 726 virtual void prepare_for_verify(); | |
| 727 | |
| 728 virtual void gc_epilogue(bool full); | |
| 729 | |
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730 virtual void record_spaces_top(); |
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731 |
| 0 | 732 virtual void verify(bool allow_dirty); |
| 733 virtual void print_on(outputStream* st) const; | |
| 734 }; |