Mercurial > hg > truffle
annotate src/share/vm/memory/generation.hpp @ 113:ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv
Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold
| author | coleenp |
|---|---|
| date | Sun, 13 Apr 2008 17:43:42 -0400 |
| parents | a61af66fc99e |
| children | d1605aabd0a1 12eea04c8b06 |
| rev | line source |
|---|---|
| 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. | |
|
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ba764ed4b6f2
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
coleenp
parents:
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diff
changeset
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298 virtual oop promote(oop obj, size_t obj_size); |
| 0 | 299 |
| 300 // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote | |
| 301 // object "obj", whose original mark word was "m", and whose size is | |
| 302 // "word_sz". If possible, allocate space for "obj", copy obj into it | |
| 303 // (taking care to copy "m" into the mark word when done, since the mark | |
| 304 // word of "obj" may have been overwritten with a forwarding pointer, and | |
| 305 // also taking care to copy the klass pointer *last*. Returns the new | |
| 306 // object if successful, or else NULL. | |
| 307 virtual oop par_promote(int thread_num, | |
| 308 oop obj, markOop m, size_t word_sz); | |
| 309 | |
| 310 // Undo, if possible, the most recent par_promote_alloc allocation by | |
| 311 // "thread_num" ("obj", of "word_sz"). | |
| 312 virtual void par_promote_alloc_undo(int thread_num, | |
| 313 HeapWord* obj, size_t word_sz); | |
| 314 | |
| 315 // Informs the current generation that all par_promote_alloc's in the | |
| 316 // collection have been completed; any supporting data structures can be | |
| 317 // reset. Default is to do nothing. | |
| 318 virtual void par_promote_alloc_done(int thread_num) {} | |
| 319 | |
| 320 // Informs the current generation that all oop_since_save_marks_iterates | |
| 321 // performed by "thread_num" in the current collection, if any, have been | |
| 322 // completed; any supporting data structures can be reset. Default is to | |
| 323 // do nothing. | |
| 324 virtual void par_oop_since_save_marks_iterate_done(int thread_num) {} | |
| 325 | |
| 326 // This generation will collect all younger generations | |
| 327 // during a full collection. | |
| 328 virtual bool full_collects_younger_generations() const { return false; } | |
| 329 | |
| 330 // This generation does in-place marking, meaning that mark words | |
| 331 // are mutated during the marking phase and presumably reinitialized | |
| 332 // to a canonical value after the GC. This is currently used by the | |
| 333 // biased locking implementation to determine whether additional | |
| 334 // work is required during the GC prologue and epilogue. | |
| 335 virtual bool performs_in_place_marking() const { return true; } | |
| 336 | |
| 337 // Returns "true" iff collect() should subsequently be called on this | |
| 338 // this generation. See comment below. | |
| 339 // This is a generic implementation which can be overridden. | |
| 340 // | |
| 341 // Note: in the current (1.4) implementation, when genCollectedHeap's | |
| 342 // incremental_collection_will_fail flag is set, all allocations are | |
| 343 // slow path (the only fast-path place to allocate is DefNew, which | |
| 344 // will be full if the flag is set). | |
| 345 // Thus, older generations which collect younger generations should | |
| 346 // test this flag and collect if it is set. | |
| 347 virtual bool should_collect(bool full, | |
| 348 size_t word_size, | |
| 349 bool is_tlab) { | |
| 350 return (full || should_allocate(word_size, is_tlab)); | |
| 351 } | |
| 352 | |
| 353 // Perform a garbage collection. | |
| 354 // If full is true attempt a full garbage collection of this generation. | |
| 355 // Otherwise, attempting to (at least) free enough space to support an | |
| 356 // allocation of the given "word_size". | |
| 357 virtual void collect(bool full, | |
| 358 bool clear_all_soft_refs, | |
| 359 size_t word_size, | |
| 360 bool is_tlab) = 0; | |
| 361 | |
| 362 // Perform a heap collection, attempting to create (at least) enough | |
| 363 // space to support an allocation of the given "word_size". If | |
| 364 // successful, perform the allocation and return the resulting | |
| 365 // "oop" (initializing the allocated block). If the allocation is | |
| 366 // still unsuccessful, return "NULL". | |
| 367 virtual HeapWord* expand_and_allocate(size_t word_size, | |
| 368 bool is_tlab, | |
| 369 bool parallel = false) = 0; | |
| 370 | |
| 371 // Some generations may require some cleanup or preparation actions before | |
| 372 // allowing a collection. The default is to do nothing. | |
| 373 virtual void gc_prologue(bool full) {}; | |
| 374 | |
| 375 // Some generations may require some cleanup actions after a collection. | |
| 376 // The default is to do nothing. | |
| 377 virtual void gc_epilogue(bool full) {}; | |
| 378 | |
| 379 // Some generations may need to be "fixed-up" after some allocation | |
| 380 // activity to make them parsable again. The default is to do nothing. | |
| 381 virtual void ensure_parsability() {}; | |
| 382 | |
| 383 // Time (in ms) when we were last collected or now if a collection is | |
| 384 // in progress. | |
| 385 virtual jlong time_of_last_gc(jlong now) { | |
| 386 // XXX See note in genCollectedHeap::millis_since_last_gc() | |
| 387 NOT_PRODUCT( | |
| 388 if (now < _time_of_last_gc) { | |
| 389 warning("time warp: %d to %d", _time_of_last_gc, now); | |
| 390 } | |
| 391 ) | |
| 392 return _time_of_last_gc; | |
| 393 } | |
| 394 | |
| 395 virtual void update_time_of_last_gc(jlong now) { | |
| 396 _time_of_last_gc = now; | |
| 397 } | |
| 398 | |
| 399 // Generations may keep statistics about collection. This | |
| 400 // method updates those statistics. current_level is | |
| 401 // the level of the collection that has most recently | |
| 402 // occurred. This allows the generation to decide what | |
| 403 // statistics are valid to collect. For example, the | |
| 404 // generation can decide to gather the amount of promoted data | |
| 405 // if the collection of the younger generations has completed. | |
| 406 GCStats* gc_stats() const { return _gc_stats; } | |
| 407 virtual void update_gc_stats(int current_level, bool full) {} | |
| 408 | |
| 409 // Mark sweep support phase2 | |
| 410 virtual void prepare_for_compaction(CompactPoint* cp); | |
| 411 // Mark sweep support phase3 | |
| 412 virtual void pre_adjust_pointers() {ShouldNotReachHere();} | |
| 413 virtual void adjust_pointers(); | |
| 414 // Mark sweep support phase4 | |
| 415 virtual void compact(); | |
| 416 virtual void post_compact() {ShouldNotReachHere();} | |
| 417 | |
| 418 // Support for CMS's rescan. In this general form we return a pointer | |
| 419 // to an abstract object that can be used, based on specific previously | |
| 420 // decided protocols, to exchange information between generations, | |
| 421 // information that may be useful for speeding up certain types of | |
| 422 // garbage collectors. A NULL value indicates to the client that | |
| 423 // no data recording is expected by the provider. The data-recorder is | |
| 424 // expected to be GC worker thread-local, with the worker index | |
| 425 // indicated by "thr_num". | |
| 426 virtual void* get_data_recorder(int thr_num) { return NULL; } | |
| 427 | |
| 428 // Some generations may require some cleanup actions before allowing | |
| 429 // a verification. | |
| 430 virtual void prepare_for_verify() {}; | |
| 431 | |
| 432 // Accessing "marks". | |
| 433 | |
| 434 // This function gives a generation a chance to note a point between | |
| 435 // collections. For example, a contiguous generation might note the | |
| 436 // beginning allocation point post-collection, which might allow some later | |
| 437 // operations to be optimized. | |
| 438 virtual void save_marks() {} | |
| 439 | |
| 440 // This function allows generations to initialize any "saved marks". That | |
| 441 // is, should only be called when the generation is empty. | |
| 442 virtual void reset_saved_marks() {} | |
| 443 | |
| 444 // This function is "true" iff any no allocations have occurred in the | |
| 445 // generation since the last call to "save_marks". | |
| 446 virtual bool no_allocs_since_save_marks() = 0; | |
| 447 | |
| 448 // Apply "cl->apply" to (the addresses of) all reference fields in objects | |
| 449 // allocated in the current generation since the last call to "save_marks". | |
| 450 // If more objects are allocated in this generation as a result of applying | |
| 451 // the closure, iterates over reference fields in those objects as well. | |
| 452 // Calls "save_marks" at the end of the iteration. | |
| 453 // General signature... | |
| 454 virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0; | |
| 455 // ...and specializations for de-virtualization. (The general | |
| 456 // implemention of the _nv versions call the virtual version. | |
| 457 // Note that the _nv suffix is not really semantically necessary, | |
| 458 // but it avoids some not-so-useful warnings on Solaris.) | |
| 459 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
| 460 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ | |
| 461 oop_since_save_marks_iterate_v((OopsInGenClosure*)cl); \ | |
| 462 } | |
| 463 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL) | |
| 464 | |
| 465 #undef Generation_SINCE_SAVE_MARKS_DECL | |
| 466 | |
| 467 // The "requestor" generation is performing some garbage collection | |
| 468 // action for which it would be useful to have scratch space. If | |
| 469 // the target is not the requestor, no gc actions will be required | |
| 470 // of the target. The requestor promises to allocate no more than | |
| 471 // "max_alloc_words" in the target generation (via promotion say, | |
| 472 // if the requestor is a young generation and the target is older). | |
| 473 // If the target generation can provide any scratch space, it adds | |
| 474 // it to "list", leaving "list" pointing to the head of the | |
| 475 // augmented list. The default is to offer no space. | |
| 476 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor, | |
| 477 size_t max_alloc_words) {} | |
| 478 | |
| 479 // When an older generation has been collected, and perhaps resized, | |
| 480 // this method will be invoked on all younger generations (from older to | |
| 481 // younger), allowing them to resize themselves as appropriate. | |
| 482 virtual void compute_new_size() = 0; | |
| 483 | |
| 484 // Printing | |
| 485 virtual const char* name() const = 0; | |
| 486 virtual const char* short_name() const = 0; | |
| 487 | |
| 488 int level() const { return _level; } | |
| 489 | |
| 490 // Attributes | |
| 491 | |
| 492 // True iff the given generation may only be the youngest generation. | |
| 493 virtual bool must_be_youngest() const = 0; | |
| 494 // True iff the given generation may only be the oldest generation. | |
| 495 virtual bool must_be_oldest() const = 0; | |
| 496 | |
| 497 // Reference Processing accessor | |
| 498 ReferenceProcessor* const ref_processor() { return _ref_processor; } | |
| 499 | |
| 500 // Iteration. | |
| 501 | |
| 502 // Iterate over all the ref-containing fields of all objects in the | |
| 503 // generation, calling "cl.do_oop" on each. | |
| 504 virtual void oop_iterate(OopClosure* cl); | |
| 505 | |
| 506 // Same as above, restricted to the intersection of a memory region and | |
| 507 // the generation. | |
| 508 virtual void oop_iterate(MemRegion mr, OopClosure* cl); | |
| 509 | |
| 510 // Iterate over all objects in the generation, calling "cl.do_object" on | |
| 511 // each. | |
| 512 virtual void object_iterate(ObjectClosure* cl); | |
| 513 | |
| 514 // Iterate over all objects allocated in the generation since the last | |
| 515 // collection, calling "cl.do_object" on each. The generation must have | |
| 516 // been initialized properly to support this function, or else this call | |
| 517 // will fail. | |
| 518 virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0; | |
| 519 | |
| 520 // Apply "cl->do_oop" to (the address of) all and only all the ref fields | |
| 521 // in the current generation that contain pointers to objects in younger | |
| 522 // generations. Objects allocated since the last "save_marks" call are | |
| 523 // excluded. | |
| 524 virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0; | |
| 525 | |
| 526 // Inform a generation that it longer contains references to objects | |
| 527 // in any younger generation. [e.g. Because younger gens are empty, | |
| 528 // clear the card table.] | |
| 529 virtual void clear_remembered_set() { } | |
| 530 | |
| 531 // Inform a generation that some of its objects have moved. [e.g. The | |
| 532 // generation's spaces were compacted, invalidating the card table.] | |
| 533 virtual void invalidate_remembered_set() { } | |
| 534 | |
| 535 // Block abstraction. | |
| 536 | |
| 537 // Returns the address of the start of the "block" that contains the | |
| 538 // address "addr". We say "blocks" instead of "object" since some heaps | |
| 539 // may not pack objects densely; a chunk may either be an object or a | |
| 540 // non-object. | |
| 541 virtual HeapWord* block_start(const void* addr) const; | |
| 542 | |
| 543 // Requires "addr" to be the start of a chunk, and returns its size. | |
| 544 // "addr + size" is required to be the start of a new chunk, or the end | |
| 545 // of the active area of the heap. | |
| 546 virtual size_t block_size(const HeapWord* addr) const ; | |
| 547 | |
| 548 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
| 549 // the block is an object. | |
| 550 virtual bool block_is_obj(const HeapWord* addr) const; | |
| 551 | |
| 552 | |
| 553 // PrintGC, PrintGCDetails support | |
| 554 void print_heap_change(size_t prev_used) const; | |
| 555 | |
| 556 // PrintHeapAtGC support | |
| 557 virtual void print() const; | |
| 558 virtual void print_on(outputStream* st) const; | |
| 559 | |
| 560 virtual void verify(bool allow_dirty) = 0; | |
| 561 | |
| 562 struct StatRecord { | |
| 563 int invocations; | |
| 564 elapsedTimer accumulated_time; | |
| 565 StatRecord() : | |
| 566 invocations(0), | |
| 567 accumulated_time(elapsedTimer()) {} | |
| 568 }; | |
| 569 private: | |
| 570 StatRecord _stat_record; | |
| 571 public: | |
| 572 StatRecord* stat_record() { return &_stat_record; } | |
| 573 | |
| 574 virtual void print_summary_info(); | |
| 575 virtual void print_summary_info_on(outputStream* st); | |
| 576 | |
| 577 // Performance Counter support | |
| 578 virtual void update_counters() = 0; | |
| 579 virtual CollectorCounters* counters() { return _gc_counters; } | |
| 580 }; | |
| 581 | |
| 582 // Class CardGeneration is a generation that is covered by a card table, | |
| 583 // and uses a card-size block-offset array to implement block_start. | |
| 584 | |
| 585 // class BlockOffsetArray; | |
| 586 // class BlockOffsetArrayContigSpace; | |
| 587 class BlockOffsetSharedArray; | |
| 588 | |
| 589 class CardGeneration: public Generation { | |
| 590 friend class VMStructs; | |
| 591 protected: | |
| 592 // This is shared with other generations. | |
| 593 GenRemSet* _rs; | |
| 594 // This is local to this generation. | |
| 595 BlockOffsetSharedArray* _bts; | |
| 596 | |
| 597 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level, | |
| 598 GenRemSet* remset); | |
| 599 | |
| 600 public: | |
| 601 | |
| 602 virtual void clear_remembered_set(); | |
| 603 | |
| 604 virtual void invalidate_remembered_set(); | |
| 605 | |
| 606 virtual void prepare_for_verify(); | |
| 607 }; | |
| 608 | |
| 609 // OneContigSpaceCardGeneration models a heap of old objects contained in a single | |
| 610 // contiguous space. | |
| 611 // | |
| 612 // Garbage collection is performed using mark-compact. | |
| 613 | |
| 614 class OneContigSpaceCardGeneration: public CardGeneration { | |
| 615 friend class VMStructs; | |
| 616 // Abstractly, this is a subtype that gets access to protected fields. | |
| 617 friend class CompactingPermGen; | |
| 618 friend class VM_PopulateDumpSharedSpace; | |
| 619 | |
| 620 protected: | |
| 621 size_t _min_heap_delta_bytes; // Minimum amount to expand. | |
| 622 ContiguousSpace* _the_space; // actual space holding objects | |
| 623 WaterMark _last_gc; // watermark between objects allocated before | |
| 624 // and after last GC. | |
| 625 | |
| 626 // Grow generation with specified size (returns false if unable to grow) | |
| 627 bool grow_by(size_t bytes); | |
| 628 // Grow generation to reserved size. | |
| 629 bool grow_to_reserved(); | |
| 630 // Shrink generation with specified size (returns false if unable to shrink) | |
| 631 void shrink_by(size_t bytes); | |
| 632 | |
| 633 // Allocation failure | |
| 634 void expand(size_t bytes, size_t expand_bytes); | |
| 635 void shrink(size_t bytes); | |
| 636 | |
| 637 // Accessing spaces | |
| 638 ContiguousSpace* the_space() const { return _the_space; } | |
| 639 | |
| 640 public: | |
| 641 OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size, | |
| 642 size_t min_heap_delta_bytes, | |
| 643 int level, GenRemSet* remset, | |
| 644 ContiguousSpace* space) : | |
| 645 CardGeneration(rs, initial_byte_size, level, remset), | |
| 646 _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes) | |
| 647 {} | |
| 648 | |
| 649 inline bool is_in(const void* p) const; | |
| 650 | |
| 651 // Space enquiries | |
| 652 size_t capacity() const; | |
| 653 size_t used() const; | |
| 654 size_t free() const; | |
| 655 | |
| 656 MemRegion used_region() const; | |
| 657 | |
| 658 size_t unsafe_max_alloc_nogc() const; | |
| 659 size_t contiguous_available() const; | |
| 660 | |
| 661 // Iteration | |
| 662 void object_iterate(ObjectClosure* blk); | |
| 663 void space_iterate(SpaceClosure* blk, bool usedOnly = false); | |
| 664 void object_iterate_since_last_GC(ObjectClosure* cl); | |
| 665 | |
| 666 void younger_refs_iterate(OopsInGenClosure* blk); | |
| 667 | |
| 668 inline CompactibleSpace* first_compaction_space() const; | |
| 669 | |
| 670 virtual inline HeapWord* allocate(size_t word_size, bool is_tlab); | |
| 671 virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab); | |
| 672 | |
| 673 // Accessing marks | |
| 674 inline WaterMark top_mark(); | |
| 675 inline WaterMark bottom_mark(); | |
| 676 | |
| 677 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ | |
| 678 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl); | |
| 679 OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v) | |
| 680 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL) | |
| 681 | |
| 682 void save_marks(); | |
| 683 void reset_saved_marks(); | |
| 684 bool no_allocs_since_save_marks(); | |
| 685 | |
| 686 inline size_t block_size(const HeapWord* addr) const; | |
| 687 | |
| 688 inline bool block_is_obj(const HeapWord* addr) const; | |
| 689 | |
| 690 virtual void collect(bool full, | |
| 691 bool clear_all_soft_refs, | |
| 692 size_t size, | |
| 693 bool is_tlab); | |
| 694 HeapWord* expand_and_allocate(size_t size, | |
| 695 bool is_tlab, | |
| 696 bool parallel = false); | |
| 697 | |
| 698 virtual void prepare_for_verify(); | |
| 699 | |
| 700 virtual void gc_epilogue(bool full); | |
| 701 | |
| 702 virtual void verify(bool allow_dirty); | |
| 703 virtual void print_on(outputStream* st) const; | |
| 704 }; |