annotate src/share/vm/memory/generation.hpp @ 196:d1605aabd0a1

6719955: Update copyright year Summary: Update copyright year for files that have been modified in 2008 Reviewed-by: ohair, tbell
author xdono
date Wed, 02 Jul 2008 12:55:16 -0700
parents ba764ed4b6f2
children 850fdf70db2b
rev   line source
duke@0 1 /*
xdono@196 2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
duke@0 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@0 4 *
duke@0 5 * This code is free software; you can redistribute it and/or modify it
duke@0 6 * under the terms of the GNU General Public License version 2 only, as
duke@0 7 * published by the Free Software Foundation.
duke@0 8 *
duke@0 9 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@0 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@0 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@0 12 * version 2 for more details (a copy is included in the LICENSE file that
duke@0 13 * accompanied this code).
duke@0 14 *
duke@0 15 * You should have received a copy of the GNU General Public License version
duke@0 16 * 2 along with this work; if not, write to the Free Software Foundation,
duke@0 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@0 18 *
duke@0 19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@0 20 * CA 95054 USA or visit www.sun.com if you need additional information or
duke@0 21 * have any questions.
duke@0 22 *
duke@0 23 */
duke@0 24
duke@0 25 // A Generation models a heap area for similarly-aged objects.
duke@0 26 // It will contain one ore more spaces holding the actual objects.
duke@0 27 //
duke@0 28 // The Generation class hierarchy:
duke@0 29 //
duke@0 30 // Generation - abstract base class
duke@0 31 // - DefNewGeneration - allocation area (copy collected)
duke@0 32 // - ParNewGeneration - a DefNewGeneration that is collected by
duke@0 33 // several threads
duke@0 34 // - CardGeneration - abstract class adding offset array behavior
duke@0 35 // - OneContigSpaceCardGeneration - abstract class holding a single
duke@0 36 // contiguous space with card marking
duke@0 37 // - TenuredGeneration - tenured (old object) space (markSweepCompact)
duke@0 38 // - CompactingPermGenGen - reflective object area (klasses, methods, symbols, ...)
duke@0 39 // - ConcurrentMarkSweepGeneration - Mostly Concurrent Mark Sweep Generation
duke@0 40 // (Detlefs-Printezis refinement of
duke@0 41 // Boehm-Demers-Schenker)
duke@0 42 //
duke@0 43 // The system configurations currently allowed are:
duke@0 44 //
duke@0 45 // DefNewGeneration + TenuredGeneration + PermGeneration
duke@0 46 // DefNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen
duke@0 47 //
duke@0 48 // ParNewGeneration + TenuredGeneration + PermGeneration
duke@0 49 // ParNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen
duke@0 50 //
duke@0 51
duke@0 52 class DefNewGeneration;
duke@0 53 class GenerationSpec;
duke@0 54 class CompactibleSpace;
duke@0 55 class ContiguousSpace;
duke@0 56 class CompactPoint;
duke@0 57 class OopsInGenClosure;
duke@0 58 class OopClosure;
duke@0 59 class ScanClosure;
duke@0 60 class FastScanClosure;
duke@0 61 class GenCollectedHeap;
duke@0 62 class GenRemSet;
duke@0 63 class GCStats;
duke@0 64
duke@0 65 // A "ScratchBlock" represents a block of memory in one generation usable by
duke@0 66 // another. It represents "num_words" free words, starting at and including
duke@0 67 // the address of "this".
duke@0 68 struct ScratchBlock {
duke@0 69 ScratchBlock* next;
duke@0 70 size_t num_words;
duke@0 71 HeapWord scratch_space[1]; // Actually, of size "num_words-2" (assuming
duke@0 72 // first two fields are word-sized.)
duke@0 73 };
duke@0 74
duke@0 75
duke@0 76 class Generation: public CHeapObj {
duke@0 77 friend class VMStructs;
duke@0 78 private:
duke@0 79 jlong _time_of_last_gc; // time when last gc on this generation happened (ms)
duke@0 80 MemRegion _prev_used_region; // for collectors that want to "remember" a value for
duke@0 81 // used region at some specific point during collection.
duke@0 82
duke@0 83 protected:
duke@0 84 // Minimum and maximum addresses for memory reserved (not necessarily
duke@0 85 // committed) for generation.
duke@0 86 // Used by card marking code. Must not overlap with address ranges of
duke@0 87 // other generations.
duke@0 88 MemRegion _reserved;
duke@0 89
duke@0 90 // Memory area reserved for generation
duke@0 91 VirtualSpace _virtual_space;
duke@0 92
duke@0 93 // Level in the generation hierarchy.
duke@0 94 int _level;
duke@0 95
duke@0 96 // ("Weak") Reference processing support
duke@0 97 ReferenceProcessor* _ref_processor;
duke@0 98
duke@0 99 // Performance Counters
duke@0 100 CollectorCounters* _gc_counters;
duke@0 101
duke@0 102 // Statistics for garbage collection
duke@0 103 GCStats* _gc_stats;
duke@0 104
duke@0 105 // Returns the next generation in the configuration, or else NULL if this
duke@0 106 // is the highest generation.
duke@0 107 Generation* next_gen() const;
duke@0 108
duke@0 109 // Initialize the generation.
duke@0 110 Generation(ReservedSpace rs, size_t initial_byte_size, int level);
duke@0 111
duke@0 112 // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in
duke@0 113 // "sp" that point into younger generations.
duke@0 114 // The iteration is only over objects allocated at the start of the
duke@0 115 // iterations; objects allocated as a result of applying the closure are
duke@0 116 // not included.
duke@0 117 void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
duke@0 118
duke@0 119 public:
duke@0 120 // The set of possible generation kinds.
duke@0 121 enum Name {
duke@0 122 ASParNew,
duke@0 123 ASConcurrentMarkSweep,
duke@0 124 DefNew,
duke@0 125 ParNew,
duke@0 126 MarkSweepCompact,
duke@0 127 ConcurrentMarkSweep,
duke@0 128 Other
duke@0 129 };
duke@0 130
duke@0 131 enum SomePublicConstants {
duke@0 132 // Generations are GenGrain-aligned and have size that are multiples of
duke@0 133 // GenGrain.
duke@0 134 LogOfGenGrain = 16,
duke@0 135 GenGrain = 1 << LogOfGenGrain
duke@0 136 };
duke@0 137
duke@0 138 // allocate and initialize ("weak") refs processing support
duke@0 139 virtual void ref_processor_init();
duke@0 140 void set_ref_processor(ReferenceProcessor* rp) {
duke@0 141 assert(_ref_processor == NULL, "clobbering existing _ref_processor");
duke@0 142 _ref_processor = rp;
duke@0 143 }
duke@0 144
duke@0 145 virtual Generation::Name kind() { return Generation::Other; }
duke@0 146 GenerationSpec* spec();
duke@0 147
duke@0 148 // This properly belongs in the collector, but for now this
duke@0 149 // will do.
duke@0 150 virtual bool refs_discovery_is_atomic() const { return true; }
duke@0 151 virtual bool refs_discovery_is_mt() const { return false; }
duke@0 152
duke@0 153 // Space enquiries (results in bytes)
duke@0 154 virtual size_t capacity() const = 0; // The maximum number of object bytes the
duke@0 155 // generation can currently hold.
duke@0 156 virtual size_t used() const = 0; // The number of used bytes in the gen.
duke@0 157 virtual size_t free() const = 0; // The number of free bytes in the gen.
duke@0 158
duke@0 159 // Support for java.lang.Runtime.maxMemory(); see CollectedHeap.
duke@0 160 // Returns the total number of bytes available in a generation
duke@0 161 // for the allocation of objects.
duke@0 162 virtual size_t max_capacity() const;
duke@0 163
duke@0 164 // If this is a young generation, the maximum number of bytes that can be
duke@0 165 // allocated in this generation before a GC is triggered.
duke@0 166 virtual size_t capacity_before_gc() const { return 0; }
duke@0 167
duke@0 168 // The largest number of contiguous free bytes in the generation,
duke@0 169 // including expansion (Assumes called at a safepoint.)
duke@0 170 virtual size_t contiguous_available() const = 0;
duke@0 171 // The largest number of contiguous free bytes in this or any higher generation.
duke@0 172 virtual size_t max_contiguous_available() const;
duke@0 173
duke@0 174 // Returns true if promotions of the specified amount can
duke@0 175 // be attempted safely (without a vm failure).
duke@0 176 // Promotion of the full amount is not guaranteed but
duke@0 177 // can be attempted.
duke@0 178 // younger_handles_promotion_failure
duke@0 179 // is true if the younger generation handles a promotion
duke@0 180 // failure.
duke@0 181 virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes,
duke@0 182 bool younger_handles_promotion_failure) const;
duke@0 183
duke@0 184 // Return an estimate of the maximum allocation that could be performed
duke@0 185 // in the generation without triggering any collection or expansion
duke@0 186 // activity. It is "unsafe" because no locks are taken; the result
duke@0 187 // should be treated as an approximation, not a guarantee, for use in
duke@0 188 // heuristic resizing decisions.
duke@0 189 virtual size_t unsafe_max_alloc_nogc() const = 0;
duke@0 190
duke@0 191 // Returns true if this generation cannot be expanded further
duke@0 192 // without a GC. Override as appropriate.
duke@0 193 virtual bool is_maximal_no_gc() const {
duke@0 194 return _virtual_space.uncommitted_size() == 0;
duke@0 195 }
duke@0 196
duke@0 197 MemRegion reserved() const { return _reserved; }
duke@0 198
duke@0 199 // Returns a region guaranteed to contain all the objects in the
duke@0 200 // generation.
duke@0 201 virtual MemRegion used_region() const { return _reserved; }
duke@0 202
duke@0 203 MemRegion prev_used_region() const { return _prev_used_region; }
duke@0 204 virtual void save_used_region() { _prev_used_region = used_region(); }
duke@0 205
duke@0 206 // Returns "TRUE" iff "p" points into an allocated object in the generation.
duke@0 207 // For some kinds of generations, this may be an expensive operation.
duke@0 208 // To avoid performance problems stemming from its inadvertent use in
duke@0 209 // product jvm's, we restrict its use to assertion checking or
duke@0 210 // verification only.
duke@0 211 virtual bool is_in(const void* p) const;
duke@0 212
duke@0 213 /* Returns "TRUE" iff "p" points into the reserved area of the generation. */
duke@0 214 bool is_in_reserved(const void* p) const {
duke@0 215 return _reserved.contains(p);
duke@0 216 }
duke@0 217
duke@0 218 // Check that the generation kind is DefNewGeneration or a sub
duke@0 219 // class of DefNewGeneration and return a DefNewGeneration*
duke@0 220 DefNewGeneration* as_DefNewGeneration();
duke@0 221
duke@0 222 // If some space in the generation contains the given "addr", return a
duke@0 223 // pointer to that space, else return "NULL".
duke@0 224 virtual Space* space_containing(const void* addr) const;
duke@0 225
duke@0 226 // Iteration - do not use for time critical operations
duke@0 227 virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0;
duke@0 228
duke@0 229 // Returns the first space, if any, in the generation that can participate
duke@0 230 // in compaction, or else "NULL".
duke@0 231 virtual CompactibleSpace* first_compaction_space() const = 0;
duke@0 232
duke@0 233 // Returns "true" iff this generation should be used to allocate an
duke@0 234 // object of the given size. Young generations might
duke@0 235 // wish to exclude very large objects, for example, since, if allocated
duke@0 236 // often, they would greatly increase the frequency of young-gen
duke@0 237 // collection.
duke@0 238 virtual bool should_allocate(size_t word_size, bool is_tlab) {
duke@0 239 bool result = false;
duke@0 240 size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
duke@0 241 if (!is_tlab || supports_tlab_allocation()) {
duke@0 242 result = (word_size > 0) && (word_size < overflow_limit);
duke@0 243 }
duke@0 244 return result;
duke@0 245 }
duke@0 246
duke@0 247 // Allocate and returns a block of the requested size, or returns "NULL".
duke@0 248 // Assumes the caller has done any necessary locking.
duke@0 249 virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0;
duke@0 250
duke@0 251 // Like "allocate", but performs any necessary locking internally.
duke@0 252 virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0;
duke@0 253
duke@0 254 // A 'younger' gen has reached an allocation limit, and uses this to notify
duke@0 255 // the next older gen. The return value is a new limit, or NULL if none. The
duke@0 256 // caller must do the necessary locking.
duke@0 257 virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top,
duke@0 258 size_t word_size) {
duke@0 259 return NULL;
duke@0 260 }
duke@0 261
duke@0 262 // Some generation may offer a region for shared, contiguous allocation,
duke@0 263 // via inlined code (by exporting the address of the top and end fields
duke@0 264 // defining the extent of the contiguous allocation region.)
duke@0 265
duke@0 266 // This function returns "true" iff the heap supports this kind of
duke@0 267 // allocation. (More precisely, this means the style of allocation that
duke@0 268 // increments *top_addr()" with a CAS.) (Default is "no".)
duke@0 269 // A generation that supports this allocation style must use lock-free
duke@0 270 // allocation for *all* allocation, since there are times when lock free
duke@0 271 // allocation will be concurrent with plain "allocate" calls.
duke@0 272 virtual bool supports_inline_contig_alloc() const { return false; }
duke@0 273
duke@0 274 // These functions return the addresses of the fields that define the
duke@0 275 // boundaries of the contiguous allocation area. (These fields should be
duke@0 276 // physicall near to one another.)
duke@0 277 virtual HeapWord** top_addr() const { return NULL; }
duke@0 278 virtual HeapWord** end_addr() const { return NULL; }
duke@0 279
duke@0 280 // Thread-local allocation buffers
duke@0 281 virtual bool supports_tlab_allocation() const { return false; }
duke@0 282 virtual size_t tlab_capacity() const {
duke@0 283 guarantee(false, "Generation doesn't support thread local allocation buffers");
duke@0 284 return 0;
duke@0 285 }
duke@0 286 virtual size_t unsafe_max_tlab_alloc() const {
duke@0 287 guarantee(false, "Generation doesn't support thread local allocation buffers");
duke@0 288 return 0;
duke@0 289 }
duke@0 290
duke@0 291 // "obj" is the address of an object in a younger generation. Allocate space
duke@0 292 // for "obj" in the current (or some higher) generation, and copy "obj" into
duke@0 293 // the newly allocated space, if possible, returning the result (or NULL if
duke@0 294 // the allocation failed).
duke@0 295 //
duke@0 296 // The "obj_size" argument is just obj->size(), passed along so the caller can
duke@0 297 // avoid repeating the virtual call to retrieve it.
coleenp@113 298 virtual oop promote(oop obj, size_t obj_size);
duke@0 299
duke@0 300 // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote
duke@0 301 // object "obj", whose original mark word was "m", and whose size is
duke@0 302 // "word_sz". If possible, allocate space for "obj", copy obj into it
duke@0 303 // (taking care to copy "m" into the mark word when done, since the mark
duke@0 304 // word of "obj" may have been overwritten with a forwarding pointer, and
duke@0 305 // also taking care to copy the klass pointer *last*. Returns the new
duke@0 306 // object if successful, or else NULL.
duke@0 307 virtual oop par_promote(int thread_num,
duke@0 308 oop obj, markOop m, size_t word_sz);
duke@0 309
duke@0 310 // Undo, if possible, the most recent par_promote_alloc allocation by
duke@0 311 // "thread_num" ("obj", of "word_sz").
duke@0 312 virtual void par_promote_alloc_undo(int thread_num,
duke@0 313 HeapWord* obj, size_t word_sz);
duke@0 314
duke@0 315 // Informs the current generation that all par_promote_alloc's in the
duke@0 316 // collection have been completed; any supporting data structures can be
duke@0 317 // reset. Default is to do nothing.
duke@0 318 virtual void par_promote_alloc_done(int thread_num) {}
duke@0 319
duke@0 320 // Informs the current generation that all oop_since_save_marks_iterates
duke@0 321 // performed by "thread_num" in the current collection, if any, have been
duke@0 322 // completed; any supporting data structures can be reset. Default is to
duke@0 323 // do nothing.
duke@0 324 virtual void par_oop_since_save_marks_iterate_done(int thread_num) {}
duke@0 325
duke@0 326 // This generation will collect all younger generations
duke@0 327 // during a full collection.
duke@0 328 virtual bool full_collects_younger_generations() const { return false; }
duke@0 329
duke@0 330 // This generation does in-place marking, meaning that mark words
duke@0 331 // are mutated during the marking phase and presumably reinitialized
duke@0 332 // to a canonical value after the GC. This is currently used by the
duke@0 333 // biased locking implementation to determine whether additional
duke@0 334 // work is required during the GC prologue and epilogue.
duke@0 335 virtual bool performs_in_place_marking() const { return true; }
duke@0 336
duke@0 337 // Returns "true" iff collect() should subsequently be called on this
duke@0 338 // this generation. See comment below.
duke@0 339 // This is a generic implementation which can be overridden.
duke@0 340 //
duke@0 341 // Note: in the current (1.4) implementation, when genCollectedHeap's
duke@0 342 // incremental_collection_will_fail flag is set, all allocations are
duke@0 343 // slow path (the only fast-path place to allocate is DefNew, which
duke@0 344 // will be full if the flag is set).
duke@0 345 // Thus, older generations which collect younger generations should
duke@0 346 // test this flag and collect if it is set.
duke@0 347 virtual bool should_collect(bool full,
duke@0 348 size_t word_size,
duke@0 349 bool is_tlab) {
duke@0 350 return (full || should_allocate(word_size, is_tlab));
duke@0 351 }
duke@0 352
duke@0 353 // Perform a garbage collection.
duke@0 354 // If full is true attempt a full garbage collection of this generation.
duke@0 355 // Otherwise, attempting to (at least) free enough space to support an
duke@0 356 // allocation of the given "word_size".
duke@0 357 virtual void collect(bool full,
duke@0 358 bool clear_all_soft_refs,
duke@0 359 size_t word_size,
duke@0 360 bool is_tlab) = 0;
duke@0 361
duke@0 362 // Perform a heap collection, attempting to create (at least) enough
duke@0 363 // space to support an allocation of the given "word_size". If
duke@0 364 // successful, perform the allocation and return the resulting
duke@0 365 // "oop" (initializing the allocated block). If the allocation is
duke@0 366 // still unsuccessful, return "NULL".
duke@0 367 virtual HeapWord* expand_and_allocate(size_t word_size,
duke@0 368 bool is_tlab,
duke@0 369 bool parallel = false) = 0;
duke@0 370
duke@0 371 // Some generations may require some cleanup or preparation actions before
duke@0 372 // allowing a collection. The default is to do nothing.
duke@0 373 virtual void gc_prologue(bool full) {};
duke@0 374
duke@0 375 // Some generations may require some cleanup actions after a collection.
duke@0 376 // The default is to do nothing.
duke@0 377 virtual void gc_epilogue(bool full) {};
duke@0 378
duke@0 379 // Some generations may need to be "fixed-up" after some allocation
duke@0 380 // activity to make them parsable again. The default is to do nothing.
duke@0 381 virtual void ensure_parsability() {};
duke@0 382
duke@0 383 // Time (in ms) when we were last collected or now if a collection is
duke@0 384 // in progress.
duke@0 385 virtual jlong time_of_last_gc(jlong now) {
duke@0 386 // XXX See note in genCollectedHeap::millis_since_last_gc()
duke@0 387 NOT_PRODUCT(
duke@0 388 if (now < _time_of_last_gc) {
duke@0 389 warning("time warp: %d to %d", _time_of_last_gc, now);
duke@0 390 }
duke@0 391 )
duke@0 392 return _time_of_last_gc;
duke@0 393 }
duke@0 394
duke@0 395 virtual void update_time_of_last_gc(jlong now) {
duke@0 396 _time_of_last_gc = now;
duke@0 397 }
duke@0 398
duke@0 399 // Generations may keep statistics about collection. This
duke@0 400 // method updates those statistics. current_level is
duke@0 401 // the level of the collection that has most recently
duke@0 402 // occurred. This allows the generation to decide what
duke@0 403 // statistics are valid to collect. For example, the
duke@0 404 // generation can decide to gather the amount of promoted data
duke@0 405 // if the collection of the younger generations has completed.
duke@0 406 GCStats* gc_stats() const { return _gc_stats; }
duke@0 407 virtual void update_gc_stats(int current_level, bool full) {}
duke@0 408
duke@0 409 // Mark sweep support phase2
duke@0 410 virtual void prepare_for_compaction(CompactPoint* cp);
duke@0 411 // Mark sweep support phase3
duke@0 412 virtual void pre_adjust_pointers() {ShouldNotReachHere();}
duke@0 413 virtual void adjust_pointers();
duke@0 414 // Mark sweep support phase4
duke@0 415 virtual void compact();
duke@0 416 virtual void post_compact() {ShouldNotReachHere();}
duke@0 417
duke@0 418 // Support for CMS's rescan. In this general form we return a pointer
duke@0 419 // to an abstract object that can be used, based on specific previously
duke@0 420 // decided protocols, to exchange information between generations,
duke@0 421 // information that may be useful for speeding up certain types of
duke@0 422 // garbage collectors. A NULL value indicates to the client that
duke@0 423 // no data recording is expected by the provider. The data-recorder is
duke@0 424 // expected to be GC worker thread-local, with the worker index
duke@0 425 // indicated by "thr_num".
duke@0 426 virtual void* get_data_recorder(int thr_num) { return NULL; }
duke@0 427
duke@0 428 // Some generations may require some cleanup actions before allowing
duke@0 429 // a verification.
duke@0 430 virtual void prepare_for_verify() {};
duke@0 431
duke@0 432 // Accessing "marks".
duke@0 433
duke@0 434 // This function gives a generation a chance to note a point between
duke@0 435 // collections. For example, a contiguous generation might note the
duke@0 436 // beginning allocation point post-collection, which might allow some later
duke@0 437 // operations to be optimized.
duke@0 438 virtual void save_marks() {}
duke@0 439
duke@0 440 // This function allows generations to initialize any "saved marks". That
duke@0 441 // is, should only be called when the generation is empty.
duke@0 442 virtual void reset_saved_marks() {}
duke@0 443
duke@0 444 // This function is "true" iff any no allocations have occurred in the
duke@0 445 // generation since the last call to "save_marks".
duke@0 446 virtual bool no_allocs_since_save_marks() = 0;
duke@0 447
duke@0 448 // Apply "cl->apply" to (the addresses of) all reference fields in objects
duke@0 449 // allocated in the current generation since the last call to "save_marks".
duke@0 450 // If more objects are allocated in this generation as a result of applying
duke@0 451 // the closure, iterates over reference fields in those objects as well.
duke@0 452 // Calls "save_marks" at the end of the iteration.
duke@0 453 // General signature...
duke@0 454 virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0;
duke@0 455 // ...and specializations for de-virtualization. (The general
duke@0 456 // implemention of the _nv versions call the virtual version.
duke@0 457 // Note that the _nv suffix is not really semantically necessary,
duke@0 458 // but it avoids some not-so-useful warnings on Solaris.)
duke@0 459 #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
duke@0 460 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
duke@0 461 oop_since_save_marks_iterate_v((OopsInGenClosure*)cl); \
duke@0 462 }
duke@0 463 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL)
duke@0 464
duke@0 465 #undef Generation_SINCE_SAVE_MARKS_DECL
duke@0 466
duke@0 467 // The "requestor" generation is performing some garbage collection
duke@0 468 // action for which it would be useful to have scratch space. If
duke@0 469 // the target is not the requestor, no gc actions will be required
duke@0 470 // of the target. The requestor promises to allocate no more than
duke@0 471 // "max_alloc_words" in the target generation (via promotion say,
duke@0 472 // if the requestor is a young generation and the target is older).
duke@0 473 // If the target generation can provide any scratch space, it adds
duke@0 474 // it to "list", leaving "list" pointing to the head of the
duke@0 475 // augmented list. The default is to offer no space.
duke@0 476 virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
duke@0 477 size_t max_alloc_words) {}
duke@0 478
duke@0 479 // When an older generation has been collected, and perhaps resized,
duke@0 480 // this method will be invoked on all younger generations (from older to
duke@0 481 // younger), allowing them to resize themselves as appropriate.
duke@0 482 virtual void compute_new_size() = 0;
duke@0 483
duke@0 484 // Printing
duke@0 485 virtual const char* name() const = 0;
duke@0 486 virtual const char* short_name() const = 0;
duke@0 487
duke@0 488 int level() const { return _level; }
duke@0 489
duke@0 490 // Attributes
duke@0 491
duke@0 492 // True iff the given generation may only be the youngest generation.
duke@0 493 virtual bool must_be_youngest() const = 0;
duke@0 494 // True iff the given generation may only be the oldest generation.
duke@0 495 virtual bool must_be_oldest() const = 0;
duke@0 496
duke@0 497 // Reference Processing accessor
duke@0 498 ReferenceProcessor* const ref_processor() { return _ref_processor; }
duke@0 499
duke@0 500 // Iteration.
duke@0 501
duke@0 502 // Iterate over all the ref-containing fields of all objects in the
duke@0 503 // generation, calling "cl.do_oop" on each.
duke@0 504 virtual void oop_iterate(OopClosure* cl);
duke@0 505
duke@0 506 // Same as above, restricted to the intersection of a memory region and
duke@0 507 // the generation.
duke@0 508 virtual void oop_iterate(MemRegion mr, OopClosure* cl);
duke@0 509
duke@0 510 // Iterate over all objects in the generation, calling "cl.do_object" on
duke@0 511 // each.
duke@0 512 virtual void object_iterate(ObjectClosure* cl);
duke@0 513
duke@0 514 // Iterate over all objects allocated in the generation since the last
duke@0 515 // collection, calling "cl.do_object" on each. The generation must have
duke@0 516 // been initialized properly to support this function, or else this call
duke@0 517 // will fail.
duke@0 518 virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0;
duke@0 519
duke@0 520 // Apply "cl->do_oop" to (the address of) all and only all the ref fields
duke@0 521 // in the current generation that contain pointers to objects in younger
duke@0 522 // generations. Objects allocated since the last "save_marks" call are
duke@0 523 // excluded.
duke@0 524 virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0;
duke@0 525
duke@0 526 // Inform a generation that it longer contains references to objects
duke@0 527 // in any younger generation. [e.g. Because younger gens are empty,
duke@0 528 // clear the card table.]
duke@0 529 virtual void clear_remembered_set() { }
duke@0 530
duke@0 531 // Inform a generation that some of its objects have moved. [e.g. The
duke@0 532 // generation's spaces were compacted, invalidating the card table.]
duke@0 533 virtual void invalidate_remembered_set() { }
duke@0 534
duke@0 535 // Block abstraction.
duke@0 536
duke@0 537 // Returns the address of the start of the "block" that contains the
duke@0 538 // address "addr". We say "blocks" instead of "object" since some heaps
duke@0 539 // may not pack objects densely; a chunk may either be an object or a
duke@0 540 // non-object.
duke@0 541 virtual HeapWord* block_start(const void* addr) const;
duke@0 542
duke@0 543 // Requires "addr" to be the start of a chunk, and returns its size.
duke@0 544 // "addr + size" is required to be the start of a new chunk, or the end
duke@0 545 // of the active area of the heap.
duke@0 546 virtual size_t block_size(const HeapWord* addr) const ;
duke@0 547
duke@0 548 // Requires "addr" to be the start of a block, and returns "TRUE" iff
duke@0 549 // the block is an object.
duke@0 550 virtual bool block_is_obj(const HeapWord* addr) const;
duke@0 551
duke@0 552
duke@0 553 // PrintGC, PrintGCDetails support
duke@0 554 void print_heap_change(size_t prev_used) const;
duke@0 555
duke@0 556 // PrintHeapAtGC support
duke@0 557 virtual void print() const;
duke@0 558 virtual void print_on(outputStream* st) const;
duke@0 559
duke@0 560 virtual void verify(bool allow_dirty) = 0;
duke@0 561
duke@0 562 struct StatRecord {
duke@0 563 int invocations;
duke@0 564 elapsedTimer accumulated_time;
duke@0 565 StatRecord() :
duke@0 566 invocations(0),
duke@0 567 accumulated_time(elapsedTimer()) {}
duke@0 568 };
duke@0 569 private:
duke@0 570 StatRecord _stat_record;
duke@0 571 public:
duke@0 572 StatRecord* stat_record() { return &_stat_record; }
duke@0 573
duke@0 574 virtual void print_summary_info();
duke@0 575 virtual void print_summary_info_on(outputStream* st);
duke@0 576
duke@0 577 // Performance Counter support
duke@0 578 virtual void update_counters() = 0;
duke@0 579 virtual CollectorCounters* counters() { return _gc_counters; }
duke@0 580 };
duke@0 581
duke@0 582 // Class CardGeneration is a generation that is covered by a card table,
duke@0 583 // and uses a card-size block-offset array to implement block_start.
duke@0 584
duke@0 585 // class BlockOffsetArray;
duke@0 586 // class BlockOffsetArrayContigSpace;
duke@0 587 class BlockOffsetSharedArray;
duke@0 588
duke@0 589 class CardGeneration: public Generation {
duke@0 590 friend class VMStructs;
duke@0 591 protected:
duke@0 592 // This is shared with other generations.
duke@0 593 GenRemSet* _rs;
duke@0 594 // This is local to this generation.
duke@0 595 BlockOffsetSharedArray* _bts;
duke@0 596
duke@0 597 CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
duke@0 598 GenRemSet* remset);
duke@0 599
duke@0 600 public:
duke@0 601
duke@0 602 virtual void clear_remembered_set();
duke@0 603
duke@0 604 virtual void invalidate_remembered_set();
duke@0 605
duke@0 606 virtual void prepare_for_verify();
duke@0 607 };
duke@0 608
duke@0 609 // OneContigSpaceCardGeneration models a heap of old objects contained in a single
duke@0 610 // contiguous space.
duke@0 611 //
duke@0 612 // Garbage collection is performed using mark-compact.
duke@0 613
duke@0 614 class OneContigSpaceCardGeneration: public CardGeneration {
duke@0 615 friend class VMStructs;
duke@0 616 // Abstractly, this is a subtype that gets access to protected fields.
duke@0 617 friend class CompactingPermGen;
duke@0 618 friend class VM_PopulateDumpSharedSpace;
duke@0 619
duke@0 620 protected:
duke@0 621 size_t _min_heap_delta_bytes; // Minimum amount to expand.
duke@0 622 ContiguousSpace* _the_space; // actual space holding objects
duke@0 623 WaterMark _last_gc; // watermark between objects allocated before
duke@0 624 // and after last GC.
duke@0 625
duke@0 626 // Grow generation with specified size (returns false if unable to grow)
duke@0 627 bool grow_by(size_t bytes);
duke@0 628 // Grow generation to reserved size.
duke@0 629 bool grow_to_reserved();
duke@0 630 // Shrink generation with specified size (returns false if unable to shrink)
duke@0 631 void shrink_by(size_t bytes);
duke@0 632
duke@0 633 // Allocation failure
duke@0 634 void expand(size_t bytes, size_t expand_bytes);
duke@0 635 void shrink(size_t bytes);
duke@0 636
duke@0 637 // Accessing spaces
duke@0 638 ContiguousSpace* the_space() const { return _the_space; }
duke@0 639
duke@0 640 public:
duke@0 641 OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size,
duke@0 642 size_t min_heap_delta_bytes,
duke@0 643 int level, GenRemSet* remset,
duke@0 644 ContiguousSpace* space) :
duke@0 645 CardGeneration(rs, initial_byte_size, level, remset),
duke@0 646 _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes)
duke@0 647 {}
duke@0 648
duke@0 649 inline bool is_in(const void* p) const;
duke@0 650
duke@0 651 // Space enquiries
duke@0 652 size_t capacity() const;
duke@0 653 size_t used() const;
duke@0 654 size_t free() const;
duke@0 655
duke@0 656 MemRegion used_region() const;
duke@0 657
duke@0 658 size_t unsafe_max_alloc_nogc() const;
duke@0 659 size_t contiguous_available() const;
duke@0 660
duke@0 661 // Iteration
duke@0 662 void object_iterate(ObjectClosure* blk);
duke@0 663 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
duke@0 664 void object_iterate_since_last_GC(ObjectClosure* cl);
duke@0 665
duke@0 666 void younger_refs_iterate(OopsInGenClosure* blk);
duke@0 667
duke@0 668 inline CompactibleSpace* first_compaction_space() const;
duke@0 669
duke@0 670 virtual inline HeapWord* allocate(size_t word_size, bool is_tlab);
duke@0 671 virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab);
duke@0 672
duke@0 673 // Accessing marks
duke@0 674 inline WaterMark top_mark();
duke@0 675 inline WaterMark bottom_mark();
duke@0 676
duke@0 677 #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
duke@0 678 void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
duke@0 679 OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v)
duke@0 680 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL)
duke@0 681
duke@0 682 void save_marks();
duke@0 683 void reset_saved_marks();
duke@0 684 bool no_allocs_since_save_marks();
duke@0 685
duke@0 686 inline size_t block_size(const HeapWord* addr) const;
duke@0 687
duke@0 688 inline bool block_is_obj(const HeapWord* addr) const;
duke@0 689
duke@0 690 virtual void collect(bool full,
duke@0 691 bool clear_all_soft_refs,
duke@0 692 size_t size,
duke@0 693 bool is_tlab);
duke@0 694 HeapWord* expand_and_allocate(size_t size,
duke@0 695 bool is_tlab,
duke@0 696 bool parallel = false);
duke@0 697
duke@0 698 virtual void prepare_for_verify();
duke@0 699
duke@0 700 virtual void gc_epilogue(bool full);
duke@0 701
duke@0 702 virtual void verify(bool allow_dirty);
duke@0 703 virtual void print_on(outputStream* st) const;
duke@0 704 };