1 /* 2 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP 27 28 #include "gc_implementation/parallelScavenge/objectStartArray.hpp" 29 #include "gc_implementation/parallelScavenge/parMarkBitMap.hpp" 30 #include "gc_implementation/parallelScavenge/psCompactionManager.hpp" 31 #include "gc_implementation/shared/collectorCounters.hpp" 32 #include "gc_implementation/shared/markSweep.hpp" 33 #include "gc_implementation/shared/mutableSpace.hpp" 34 #include "memory/sharedHeap.hpp" 35 #include "oops/oop.hpp" 36 37 class ParallelScavengeHeap; 38 class PSAdaptiveSizePolicy; 39 class PSYoungGen; 40 class PSOldGen; 41 class ParCompactionManager; 42 class ParallelTaskTerminator; 43 class PSParallelCompact; 44 class GCTaskManager; 45 class GCTaskQueue; 46 class PreGCValues; 47 class MoveAndUpdateClosure; 48 class RefProcTaskExecutor; 49 50 // The SplitInfo class holds the information needed to 'split' a source region 51 // so that the live data can be copied to two destination *spaces*. Normally, 52 // all the live data in a region is copied to a single destination space (e.g., 53 // everything live in a region in eden is copied entirely into the old gen). 54 // However, when the heap is nearly full, all the live data in eden may not fit 55 // into the old gen. Copying only some of the regions from eden to old gen 56 // requires finding a region that does not contain a partial object (i.e., no 57 // live object crosses the region boundary) somewhere near the last object that 58 // does fit into the old gen. Since it's not always possible to find such a 59 // region, splitting is necessary for predictable behavior. 60 // 61 // A region is always split at the end of the partial object. This avoids 62 // additional tests when calculating the new location of a pointer, which is a 63 // very hot code path. The partial object and everything to its left will be 64 // copied to another space (call it dest_space_1). The live data to the right 65 // of the partial object will be copied either within the space itself, or to a 66 // different destination space (distinct from dest_space_1). 67 // 68 // Split points are identified during the summary phase, when region 69 // destinations are computed: data about the split, including the 70 // partial_object_size, is recorded in a SplitInfo record and the 71 // partial_object_size field in the summary data is set to zero. The zeroing is 72 // possible (and necessary) since the partial object will move to a different 73 // destination space than anything to its right, thus the partial object should 74 // not affect the locations of any objects to its right. 75 // 76 // The recorded data is used during the compaction phase, but only rarely: when 77 // the partial object on the split region will be copied across a destination 78 // region boundary. This test is made once each time a region is filled, and is 79 // a simple address comparison, so the overhead is negligible (see 80 // PSParallelCompact::first_src_addr()). 81 // 82 // Notes: 83 // 84 // Only regions with partial objects are split; a region without a partial 85 // object does not need any extra bookkeeping. 86 // 87 // At most one region is split per space, so the amount of data required is 88 // constant. 89 // 90 // A region is split only when the destination space would overflow. Once that 91 // happens, the destination space is abandoned and no other data (even from 92 // other source spaces) is targeted to that destination space. Abandoning the 93 // destination space may leave a somewhat large unused area at the end, if a 94 // large object caused the overflow. 95 // 96 // Future work: 97 // 98 // More bookkeeping would be required to continue to use the destination space. 99 // The most general solution would allow data from regions in two different 100 // source spaces to be "joined" in a single destination region. At the very 101 // least, additional code would be required in next_src_region() to detect the 102 // join and skip to an out-of-order source region. If the join region was also 103 // the last destination region to which a split region was copied (the most 104 // likely case), then additional work would be needed to get fill_region() to 105 // stop iteration and switch to a new source region at the right point. Basic 106 // idea would be to use a fake value for the top of the source space. It is 107 // doable, if a bit tricky. 108 // 109 // A simpler (but less general) solution would fill the remainder of the 110 // destination region with a dummy object and continue filling the next 111 // destination region. 112 113 class SplitInfo 114 { 115 public: 116 // Return true if this split info is valid (i.e., if a split has been 117 // recorded). The very first region cannot have a partial object and thus is 118 // never split, so 0 is the 'invalid' value. 119 bool is_valid() const { return _src_region_idx > 0; } 120 121 // Return true if this split holds data for the specified source region. 122 inline bool is_split(size_t source_region) const; 123 124 // The index of the split region, the size of the partial object on that 125 // region and the destination of the partial object. 126 size_t src_region_idx() const { return _src_region_idx; } 127 size_t partial_obj_size() const { return _partial_obj_size; } 128 HeapWord* destination() const { return _destination; } 129 130 // The destination count of the partial object referenced by this split 131 // (either 1 or 2). This must be added to the destination count of the 132 // remainder of the source region. 133 unsigned int destination_count() const { return _destination_count; } 134 135 // If a word within the partial object will be written to the first word of a 136 // destination region, this is the address of the destination region; 137 // otherwise this is NULL. 138 HeapWord* dest_region_addr() const { return _dest_region_addr; } 139 140 // If a word within the partial object will be written to the first word of a 141 // destination region, this is the address of that word within the partial 142 // object; otherwise this is NULL. 143 HeapWord* first_src_addr() const { return _first_src_addr; } 144 145 // Record the data necessary to split the region src_region_idx. 146 void record(size_t src_region_idx, size_t partial_obj_size, 147 HeapWord* destination); 148 149 void clear(); 150 151 DEBUG_ONLY(void verify_clear();) 152 153 private: 154 size_t _src_region_idx; 155 size_t _partial_obj_size; 156 HeapWord* _destination; 157 unsigned int _destination_count; 158 HeapWord* _dest_region_addr; 159 HeapWord* _first_src_addr; 160 }; 161 162 inline bool SplitInfo::is_split(size_t region_idx) const 163 { 164 return _src_region_idx == region_idx && is_valid(); 165 } 166 167 class SpaceInfo 168 { 169 public: 170 MutableSpace* space() const { return _space; } 171 172 // Where the free space will start after the collection. Valid only after the 173 // summary phase completes. 174 HeapWord* new_top() const { return _new_top; } 175 176 // Allows new_top to be set. 177 HeapWord** new_top_addr() { return &_new_top; } 178 179 // Where the smallest allowable dense prefix ends (used only for perm gen). 180 HeapWord* min_dense_prefix() const { return _min_dense_prefix; } 181 182 // Where the dense prefix ends, or the compacted region begins. 183 HeapWord* dense_prefix() const { return _dense_prefix; } 184 185 // The start array for the (generation containing the) space, or NULL if there 186 // is no start array. 187 ObjectStartArray* start_array() const { return _start_array; } 188 189 SplitInfo& split_info() { return _split_info; } 190 191 void set_space(MutableSpace* s) { _space = s; } 192 void set_new_top(HeapWord* addr) { _new_top = addr; } 193 void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; } 194 void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; } 195 void set_start_array(ObjectStartArray* s) { _start_array = s; } 196 197 void publish_new_top() const { _space->set_top(_new_top); } 198 199 private: 200 MutableSpace* _space; 201 HeapWord* _new_top; 202 HeapWord* _min_dense_prefix; 203 HeapWord* _dense_prefix; 204 ObjectStartArray* _start_array; 205 SplitInfo _split_info; 206 }; 207 208 class ParallelCompactData 209 { 210 public: 211 // Sizes are in HeapWords, unless indicated otherwise. 212 static const size_t Log2RegionSize; 213 static const size_t RegionSize; 214 static const size_t RegionSizeBytes; 215 216 // Mask for the bits in a size_t to get an offset within a region. 217 static const size_t RegionSizeOffsetMask; 218 // Mask for the bits in a pointer to get an offset within a region. 219 static const size_t RegionAddrOffsetMask; 220 // Mask for the bits in a pointer to get the address of the start of a region. 221 static const size_t RegionAddrMask; 222 223 class RegionData 224 { 225 public: 226 // Destination address of the region. 227 HeapWord* destination() const { return _destination; } 228 229 // The first region containing data destined for this region. 230 size_t source_region() const { return _source_region; } 231 232 // The object (if any) starting in this region and ending in a different 233 // region that could not be updated during the main (parallel) compaction 234 // phase. This is different from _partial_obj_addr, which is an object that 235 // extends onto a source region. However, the two uses do not overlap in 236 // time, so the same field is used to save space. 237 HeapWord* deferred_obj_addr() const { return _partial_obj_addr; } 238 239 // The starting address of the partial object extending onto the region. 240 HeapWord* partial_obj_addr() const { return _partial_obj_addr; } 241 242 // Size of the partial object extending onto the region (words). 243 size_t partial_obj_size() const { return _partial_obj_size; } 244 245 // Size of live data that lies within this region due to objects that start 246 // in this region (words). This does not include the partial object 247 // extending onto the region (if any), or the part of an object that extends 248 // onto the next region (if any). 249 size_t live_obj_size() const { return _dc_and_los & los_mask; } 250 251 // Total live data that lies within the region (words). 252 size_t data_size() const { return partial_obj_size() + live_obj_size(); } 253 254 // The destination_count is the number of other regions to which data from 255 // this region will be copied. At the end of the summary phase, the valid 256 // values of destination_count are 257 // 258 // 0 - data from the region will be compacted completely into itself, or the 259 // region is empty. The region can be claimed and then filled. 260 // 1 - data from the region will be compacted into 1 other region; some 261 // data from the region may also be compacted into the region itself. 262 // 2 - data from the region will be copied to 2 other regions. 263 // 264 // During compaction as regions are emptied, the destination_count is 265 // decremented (atomically) and when it reaches 0, it can be claimed and 266 // then filled. 267 // 268 // A region is claimed for processing by atomically changing the 269 // destination_count to the claimed value (dc_claimed). After a region has 270 // been filled, the destination_count should be set to the completed value 271 // (dc_completed). 272 inline uint destination_count() const; 273 inline uint destination_count_raw() const; 274 275 // The location of the java heap data that corresponds to this region. 276 inline HeapWord* data_location() const; 277 278 // The highest address referenced by objects in this region. 279 inline HeapWord* highest_ref() const; 280 281 // Whether this region is available to be claimed, has been claimed, or has 282 // been completed. 283 // 284 // Minor subtlety: claimed() returns true if the region is marked 285 // completed(), which is desirable since a region must be claimed before it 286 // can be completed. 287 bool available() const { return _dc_and_los < dc_one; } 288 bool claimed() const { return _dc_and_los >= dc_claimed; } 289 bool completed() const { return _dc_and_los >= dc_completed; } 290 291 // These are not atomic. 292 void set_destination(HeapWord* addr) { _destination = addr; } 293 void set_source_region(size_t region) { _source_region = region; } 294 void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } 295 void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } 296 void set_partial_obj_size(size_t words) { 297 _partial_obj_size = (region_sz_t) words; 298 } 299 300 inline void set_destination_count(uint count); 301 inline void set_live_obj_size(size_t words); 302 inline void set_data_location(HeapWord* addr); 303 inline void set_completed(); 304 inline bool claim_unsafe(); 305 306 // These are atomic. 307 inline void add_live_obj(size_t words); 308 inline void set_highest_ref(HeapWord* addr); 309 inline void decrement_destination_count(); 310 inline bool claim(); 311 312 private: 313 // The type used to represent object sizes within a region. 314 typedef uint region_sz_t; 315 316 // Constants for manipulating the _dc_and_los field, which holds both the 317 // destination count and live obj size. The live obj size lives at the 318 // least significant end so no masking is necessary when adding. 319 static const region_sz_t dc_shift; // Shift amount. 320 static const region_sz_t dc_mask; // Mask for destination count. 321 static const region_sz_t dc_one; // 1, shifted appropriately. 322 static const region_sz_t dc_claimed; // Region has been claimed. 323 static const region_sz_t dc_completed; // Region has been completed. 324 static const region_sz_t los_mask; // Mask for live obj size. 325 326 HeapWord* _destination; 327 size_t _source_region; 328 HeapWord* _partial_obj_addr; 329 region_sz_t _partial_obj_size; 330 region_sz_t volatile _dc_and_los; 331 #ifdef ASSERT 332 // These enable optimizations that are only partially implemented. Use 333 // debug builds to prevent the code fragments from breaking. 334 HeapWord* _data_location; 335 HeapWord* _highest_ref; 336 #endif // #ifdef ASSERT 337 338 #ifdef ASSERT 339 public: 340 uint _pushed; // 0 until region is pushed onto a worker's stack 341 private: 342 #endif 343 }; 344 345 public: 346 ParallelCompactData(); 347 bool initialize(MemRegion covered_region); 348 349 size_t region_count() const { return _region_count; } 350 size_t reserved_byte_size() const { return _reserved_byte_size; } 351 352 // Convert region indices to/from RegionData pointers. 353 inline RegionData* region(size_t region_idx) const; 354 inline size_t region(const RegionData* const region_ptr) const; 355 356 // Returns true if the given address is contained within the region 357 bool region_contains(size_t region_index, HeapWord* addr); 358 359 void add_obj(HeapWord* addr, size_t len); 360 void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); } 361 362 // Fill in the regions covering [beg, end) so that no data moves; i.e., the 363 // destination of region n is simply the start of region n. The argument beg 364 // must be region-aligned; end need not be. 365 void summarize_dense_prefix(HeapWord* beg, HeapWord* end); 366 367 HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info, 368 HeapWord* destination, HeapWord* target_end, 369 HeapWord** target_next); 370 bool summarize(SplitInfo& split_info, 371 HeapWord* source_beg, HeapWord* source_end, 372 HeapWord** source_next, 373 HeapWord* target_beg, HeapWord* target_end, 374 HeapWord** target_next); 375 376 void clear(); 377 void clear_range(size_t beg_region, size_t end_region); 378 void clear_range(HeapWord* beg, HeapWord* end) { 379 clear_range(addr_to_region_idx(beg), addr_to_region_idx(end)); 380 } 381 382 // Return the number of words between addr and the start of the region 383 // containing addr. 384 inline size_t region_offset(const HeapWord* addr) const; 385 386 // Convert addresses to/from a region index or region pointer. 387 inline size_t addr_to_region_idx(const HeapWord* addr) const; 388 inline RegionData* addr_to_region_ptr(const HeapWord* addr) const; 389 inline HeapWord* region_to_addr(size_t region) const; 390 inline HeapWord* region_to_addr(size_t region, size_t offset) const; 391 inline HeapWord* region_to_addr(const RegionData* region) const; 392 393 inline HeapWord* region_align_down(HeapWord* addr) const; 394 inline HeapWord* region_align_up(HeapWord* addr) const; 395 inline bool is_region_aligned(HeapWord* addr) const; 396 397 // Return the address one past the end of the partial object. 398 HeapWord* partial_obj_end(size_t region_idx) const; 399 400 // Return the new location of the object p after the 401 // the compaction. 402 HeapWord* calc_new_pointer(HeapWord* addr); 403 404 HeapWord* calc_new_pointer(oop p) { 405 return calc_new_pointer((HeapWord*) p); 406 } 407 408 #ifdef ASSERT 409 void verify_clear(const PSVirtualSpace* vspace); 410 void verify_clear(); 411 #endif // #ifdef ASSERT 412 413 private: 414 bool initialize_region_data(size_t region_size); 415 PSVirtualSpace* create_vspace(size_t count, size_t element_size); 416 417 private: 418 HeapWord* _region_start; 419 #ifdef ASSERT 420 HeapWord* _region_end; 421 #endif // #ifdef ASSERT 422 423 PSVirtualSpace* _region_vspace; 424 size_t _reserved_byte_size; 425 RegionData* _region_data; 426 size_t _region_count; 427 }; 428 429 inline uint 430 ParallelCompactData::RegionData::destination_count_raw() const 431 { 432 return _dc_and_los & dc_mask; 433 } 434 435 inline uint 436 ParallelCompactData::RegionData::destination_count() const 437 { 438 return destination_count_raw() >> dc_shift; 439 } 440 441 inline void 442 ParallelCompactData::RegionData::set_destination_count(uint count) 443 { 444 assert(count <= (dc_completed >> dc_shift), "count too large"); 445 const region_sz_t live_sz = (region_sz_t) live_obj_size(); 446 _dc_and_los = (count << dc_shift) | live_sz; 447 } 448 449 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words) 450 { 451 assert(words <= los_mask, "would overflow"); 452 _dc_and_los = destination_count_raw() | (region_sz_t)words; 453 } 454 455 inline void ParallelCompactData::RegionData::decrement_destination_count() 456 { 457 assert(_dc_and_los < dc_claimed, "already claimed"); 458 assert(_dc_and_los >= dc_one, "count would go negative"); 459 Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los); 460 } 461 462 inline HeapWord* ParallelCompactData::RegionData::data_location() const 463 { 464 DEBUG_ONLY(return _data_location;) 465 NOT_DEBUG(return NULL;) 466 } 467 468 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const 469 { 470 DEBUG_ONLY(return _highest_ref;) 471 NOT_DEBUG(return NULL;) 472 } 473 474 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr) 475 { 476 DEBUG_ONLY(_data_location = addr;) 477 } 478 479 inline void ParallelCompactData::RegionData::set_completed() 480 { 481 assert(claimed(), "must be claimed first"); 482 _dc_and_los = dc_completed | (region_sz_t) live_obj_size(); 483 } 484 485 // MT-unsafe claiming of a region. Should only be used during single threaded 486 // execution. 487 inline bool ParallelCompactData::RegionData::claim_unsafe() 488 { 489 if (available()) { 490 _dc_and_los |= dc_claimed; 491 return true; 492 } 493 return false; 494 } 495 496 inline void ParallelCompactData::RegionData::add_live_obj(size_t words) 497 { 498 assert(words <= (size_t)los_mask - live_obj_size(), "overflow"); 499 Atomic::add((int) words, (volatile int*) &_dc_and_los); 500 } 501 502 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr) 503 { 504 #ifdef ASSERT 505 HeapWord* tmp = _highest_ref; 506 while (addr > tmp) { 507 tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp); 508 } 509 #endif // #ifdef ASSERT 510 } 511 512 inline bool ParallelCompactData::RegionData::claim() 513 { 514 const int los = (int) live_obj_size(); 515 const int old = Atomic::cmpxchg(dc_claimed | los, 516 (volatile int*) &_dc_and_los, los); 517 return old == los; 518 } 519 520 inline ParallelCompactData::RegionData* 521 ParallelCompactData::region(size_t region_idx) const 522 { 523 assert(region_idx <= region_count(), "bad arg"); 524 return _region_data + region_idx; 525 } 526 527 inline size_t 528 ParallelCompactData::region(const RegionData* const region_ptr) const 529 { 530 assert(region_ptr >= _region_data, "bad arg"); 531 assert(region_ptr <= _region_data + region_count(), "bad arg"); 532 return pointer_delta(region_ptr, _region_data, sizeof(RegionData)); 533 } 534 535 inline size_t 536 ParallelCompactData::region_offset(const HeapWord* addr) const 537 { 538 assert(addr >= _region_start, "bad addr"); 539 assert(addr <= _region_end, "bad addr"); 540 return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize; 541 } 542 543 inline size_t 544 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const 545 { 546 assert(addr >= _region_start, "bad addr"); 547 assert(addr <= _region_end, "bad addr"); 548 return pointer_delta(addr, _region_start) >> Log2RegionSize; 549 } 550 551 inline ParallelCompactData::RegionData* 552 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const 553 { 554 return region(addr_to_region_idx(addr)); 555 } 556 557 inline HeapWord* 558 ParallelCompactData::region_to_addr(size_t region) const 559 { 560 assert(region <= _region_count, "region out of range"); 561 return _region_start + (region << Log2RegionSize); 562 } 563 564 inline HeapWord* 565 ParallelCompactData::region_to_addr(const RegionData* region) const 566 { 567 return region_to_addr(pointer_delta(region, _region_data, 568 sizeof(RegionData))); 569 } 570 571 inline HeapWord* 572 ParallelCompactData::region_to_addr(size_t region, size_t offset) const 573 { 574 assert(region <= _region_count, "region out of range"); 575 assert(offset < RegionSize, "offset too big"); // This may be too strict. 576 return region_to_addr(region) + offset; 577 } 578 579 inline HeapWord* 580 ParallelCompactData::region_align_down(HeapWord* addr) const 581 { 582 assert(addr >= _region_start, "bad addr"); 583 assert(addr < _region_end + RegionSize, "bad addr"); 584 return (HeapWord*)(size_t(addr) & RegionAddrMask); 585 } 586 587 inline HeapWord* 588 ParallelCompactData::region_align_up(HeapWord* addr) const 589 { 590 assert(addr >= _region_start, "bad addr"); 591 assert(addr <= _region_end, "bad addr"); 592 return region_align_down(addr + RegionSizeOffsetMask); 593 } 594 595 inline bool 596 ParallelCompactData::is_region_aligned(HeapWord* addr) const 597 { 598 return region_offset(addr) == 0; 599 } 600 601 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the 602 // do_addr() method. 603 // 604 // The closure is initialized with the number of heap words to process 605 // (words_remaining()), and becomes 'full' when it reaches 0. The do_addr() 606 // methods in subclasses should update the total as words are processed. Since 607 // only one subclass actually uses this mechanism to terminate iteration, the 608 // default initial value is > 0. The implementation is here and not in the 609 // single subclass that uses it to avoid making is_full() virtual, and thus 610 // adding a virtual call per live object. 611 612 class ParMarkBitMapClosure: public StackObj { 613 public: 614 typedef ParMarkBitMap::idx_t idx_t; 615 typedef ParMarkBitMap::IterationStatus IterationStatus; 616 617 public: 618 inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm, 619 size_t words = max_uintx); 620 621 inline ParCompactionManager* compaction_manager() const; 622 inline ParMarkBitMap* bitmap() const; 623 inline size_t words_remaining() const; 624 inline bool is_full() const; 625 inline HeapWord* source() const; 626 627 inline void set_source(HeapWord* addr); 628 629 virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0; 630 631 protected: 632 inline void decrement_words_remaining(size_t words); 633 634 private: 635 ParMarkBitMap* const _bitmap; 636 ParCompactionManager* const _compaction_manager; 637 DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger. 638 size_t _words_remaining; // Words left to copy. 639 640 protected: 641 HeapWord* _source; // Next addr that would be read. 642 }; 643 644 inline 645 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap, 646 ParCompactionManager* cm, 647 size_t words): 648 _bitmap(bitmap), _compaction_manager(cm) 649 #ifdef ASSERT 650 , _initial_words_remaining(words) 651 #endif 652 { 653 _words_remaining = words; 654 _source = NULL; 655 } 656 657 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const { 658 return _compaction_manager; 659 } 660 661 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const { 662 return _bitmap; 663 } 664 665 inline size_t ParMarkBitMapClosure::words_remaining() const { 666 return _words_remaining; 667 } 668 669 inline bool ParMarkBitMapClosure::is_full() const { 670 return words_remaining() == 0; 671 } 672 673 inline HeapWord* ParMarkBitMapClosure::source() const { 674 return _source; 675 } 676 677 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) { 678 _source = addr; 679 } 680 681 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) { 682 assert(_words_remaining >= words, "processed too many words"); 683 _words_remaining -= words; 684 } 685 686 // The UseParallelOldGC collector is a stop-the-world garbage collector that 687 // does parts of the collection using parallel threads. The collection includes 688 // the tenured generation and the young generation. The permanent generation is 689 // collected at the same time as the other two generations but the permanent 690 // generation is collect by a single GC thread. The permanent generation is 691 // collected serially because of the requirement that during the processing of a 692 // klass AAA, any objects reference by AAA must already have been processed. 693 // This requirement is enforced by a left (lower address) to right (higher 694 // address) sliding compaction. 695 // 696 // There are four phases of the collection. 697 // 698 // - marking phase 699 // - summary phase 700 // - compacting phase 701 // - clean up phase 702 // 703 // Roughly speaking these phases correspond, respectively, to 704 // - mark all the live objects 705 // - calculate the destination of each object at the end of the collection 706 // - move the objects to their destination 707 // - update some references and reinitialize some variables 708 // 709 // These three phases are invoked in PSParallelCompact::invoke_no_policy(). The 710 // marking phase is implemented in PSParallelCompact::marking_phase() and does a 711 // complete marking of the heap. The summary phase is implemented in 712 // PSParallelCompact::summary_phase(). The move and update phase is implemented 713 // in PSParallelCompact::compact(). 714 // 715 // A space that is being collected is divided into regions and with each region 716 // is associated an object of type ParallelCompactData. Each region is of a 717 // fixed size and typically will contain more than 1 object and may have parts 718 // of objects at the front and back of the region. 719 // 720 // region -----+---------------------+---------- 721 // objects covered [ AAA )[ BBB )[ CCC )[ DDD ) 722 // 723 // The marking phase does a complete marking of all live objects in the heap. 724 // The marking also compiles the size of the data for all live objects covered 725 // by the region. This size includes the part of any live object spanning onto 726 // the region (part of AAA if it is live) from the front, all live objects 727 // contained in the region (BBB and/or CCC if they are live), and the part of 728 // any live objects covered by the region that extends off the region (part of 729 // DDD if it is live). The marking phase uses multiple GC threads and marking 730 // is done in a bit array of type ParMarkBitMap. The marking of the bit map is 731 // done atomically as is the accumulation of the size of the live objects 732 // covered by a region. 733 // 734 // The summary phase calculates the total live data to the left of each region 735 // XXX. Based on that total and the bottom of the space, it can calculate the 736 // starting location of the live data in XXX. The summary phase calculates for 737 // each region XXX quantites such as 738 // 739 // - the amount of live data at the beginning of a region from an object 740 // entering the region. 741 // - the location of the first live data on the region 742 // - a count of the number of regions receiving live data from XXX. 743 // 744 // See ParallelCompactData for precise details. The summary phase also 745 // calculates the dense prefix for the compaction. The dense prefix is a 746 // portion at the beginning of the space that is not moved. The objects in the 747 // dense prefix do need to have their object references updated. See method 748 // summarize_dense_prefix(). 749 // 750 // The summary phase is done using 1 GC thread. 751 // 752 // The compaction phase moves objects to their new location and updates all 753 // references in the object. 754 // 755 // A current exception is that objects that cross a region boundary are moved 756 // but do not have their references updated. References are not updated because 757 // it cannot easily be determined if the klass pointer KKK for the object AAA 758 // has been updated. KKK likely resides in a region to the left of the region 759 // containing AAA. These AAA's have there references updated at the end in a 760 // clean up phase. See the method PSParallelCompact::update_deferred_objects(). 761 // An alternate strategy is being investigated for this deferral of updating. 762 // 763 // Compaction is done on a region basis. A region that is ready to be filled is 764 // put on a ready list and GC threads take region off the list and fill them. A 765 // region is ready to be filled if it empty of live objects. Such a region may 766 // have been initially empty (only contained dead objects) or may have had all 767 // its live objects copied out already. A region that compacts into itself is 768 // also ready for filling. The ready list is initially filled with empty 769 // regions and regions compacting into themselves. There is always at least 1 770 // region that can be put on the ready list. The regions are atomically added 771 // and removed from the ready list. 772 773 class PSParallelCompact : AllStatic { 774 public: 775 // Convenient access to type names. 776 typedef ParMarkBitMap::idx_t idx_t; 777 typedef ParallelCompactData::RegionData RegionData; 778 779 typedef enum { 780 old_space_id, eden_space_id, 781 from_space_id, to_space_id, last_space_id 782 } SpaceId; 783 784 public: 785 // Inline closure decls 786 // 787 class IsAliveClosure: public BoolObjectClosure { 788 public: 789 virtual bool do_object_b(oop p); 790 }; 791 792 class KeepAliveClosure: public OopClosure { 793 private: 794 ParCompactionManager* _compaction_manager; 795 protected: 796 template <class T> inline void do_oop_work(T* p); 797 public: 798 KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { } 799 virtual void do_oop(oop* p); 800 virtual void do_oop(narrowOop* p); 801 }; 802 803 class FollowStackClosure: public VoidClosure { 804 private: 805 ParCompactionManager* _compaction_manager; 806 public: 807 FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { } 808 virtual void do_void(); 809 }; 810 811 class AdjustPointerClosure: public OopClosure { 812 public: 813 virtual void do_oop(oop* p); 814 virtual void do_oop(narrowOop* p); 815 // do not walk from thread stacks to the code cache on this phase 816 virtual void do_code_blob(CodeBlob* cb) const { } 817 }; 818 819 class AdjustKlassClosure : public KlassClosure { 820 public: 821 void do_klass(Klass* klass); 822 }; 823 824 friend class KeepAliveClosure; 825 friend class FollowStackClosure; 826 friend class AdjustPointerClosure; 827 friend class AdjustKlassClosure; 828 friend class FollowKlassClosure; 829 friend class InstanceClassLoaderKlass; 830 friend class RefProcTaskProxy; 831 832 private: 833 static elapsedTimer _accumulated_time; 834 static unsigned int _total_invocations; 835 static unsigned int _maximum_compaction_gc_num; 836 static jlong _time_of_last_gc; // ms 837 static CollectorCounters* _counters; 838 static ParMarkBitMap _mark_bitmap; 839 static ParallelCompactData _summary_data; 840 static IsAliveClosure _is_alive_closure; 841 static SpaceInfo _space_info[last_space_id]; 842 static bool _print_phases; 843 static AdjustPointerClosure _adjust_pointer_closure; 844 static AdjustKlassClosure _adjust_klass_closure; 845 846 // Reference processing (used in ...follow_contents) 847 static ReferenceProcessor* _ref_processor; 848 849 // Updated location of intArrayKlassObj. 850 static Klass* _updated_int_array_klass_obj; 851 852 // Values computed at initialization and used by dead_wood_limiter(). 853 static double _dwl_mean; 854 static double _dwl_std_dev; 855 static double _dwl_first_term; 856 static double _dwl_adjustment; 857 #ifdef ASSERT 858 static bool _dwl_initialized; 859 #endif // #ifdef ASSERT 860 861 private: 862 863 static void initialize_space_info(); 864 865 // Return true if details about individual phases should be printed. 866 static inline bool print_phases(); 867 868 // Clear the marking bitmap and summary data that cover the specified space. 869 static void clear_data_covering_space(SpaceId id); 870 871 static void pre_compact(PreGCValues* pre_gc_values); 872 static void post_compact(); 873 874 // Mark live objects 875 static void marking_phase(ParCompactionManager* cm, 876 bool maximum_heap_compaction); 877 878 template <class T> 879 static inline void follow_root(ParCompactionManager* cm, T* p); 880 881 // Compute the dense prefix for the designated space. This is an experimental 882 // implementation currently not used in production. 883 static HeapWord* compute_dense_prefix_via_density(const SpaceId id, 884 bool maximum_compaction); 885 886 // Methods used to compute the dense prefix. 887 888 // Compute the value of the normal distribution at x = density. The mean and 889 // standard deviation are values saved by initialize_dead_wood_limiter(). 890 static inline double normal_distribution(double density); 891 892 // Initialize the static vars used by dead_wood_limiter(). 893 static void initialize_dead_wood_limiter(); 894 895 // Return the percentage of space that can be treated as "dead wood" (i.e., 896 // not reclaimed). 897 static double dead_wood_limiter(double density, size_t min_percent); 898 899 // Find the first (left-most) region in the range [beg, end) that has at least 900 // dead_words of dead space to the left. The argument beg must be the first 901 // region in the space that is not completely live. 902 static RegionData* dead_wood_limit_region(const RegionData* beg, 903 const RegionData* end, 904 size_t dead_words); 905 906 // Return a pointer to the first region in the range [beg, end) that is not 907 // completely full. 908 static RegionData* first_dead_space_region(const RegionData* beg, 909 const RegionData* end); 910 911 // Return a value indicating the benefit or 'yield' if the compacted region 912 // were to start (or equivalently if the dense prefix were to end) at the 913 // candidate region. Higher values are better. 914 // 915 // The value is based on the amount of space reclaimed vs. the costs of (a) 916 // updating references in the dense prefix plus (b) copying objects and 917 // updating references in the compacted region. 918 static inline double reclaimed_ratio(const RegionData* const candidate, 919 HeapWord* const bottom, 920 HeapWord* const top, 921 HeapWord* const new_top); 922 923 // Compute the dense prefix for the designated space. 924 static HeapWord* compute_dense_prefix(const SpaceId id, 925 bool maximum_compaction); 926 927 // Return true if dead space crosses onto the specified Region; bit must be 928 // the bit index corresponding to the first word of the Region. 929 static inline bool dead_space_crosses_boundary(const RegionData* region, 930 idx_t bit); 931 932 // Summary phase utility routine to fill dead space (if any) at the dense 933 // prefix boundary. Should only be called if the the dense prefix is 934 // non-empty. 935 static void fill_dense_prefix_end(SpaceId id); 936 937 // Clear the summary data source_region field for the specified addresses. 938 static void clear_source_region(HeapWord* beg_addr, HeapWord* end_addr); 939 940 #ifndef PRODUCT 941 // Routines to provoke splitting a young gen space (ParallelOldGCSplitALot). 942 943 // Fill the region [start, start + words) with live object(s). Only usable 944 // for the old and permanent generations. 945 static void fill_with_live_objects(SpaceId id, HeapWord* const start, 946 size_t words); 947 // Include the new objects in the summary data. 948 static void summarize_new_objects(SpaceId id, HeapWord* start); 949 950 // Add live objects to a survivor space since it's rare that both survivors 951 // are non-empty. 952 static void provoke_split_fill_survivor(SpaceId id); 953 954 // Add live objects and/or choose the dense prefix to provoke splitting. 955 static void provoke_split(bool & maximum_compaction); 956 #endif 957 958 static void summarize_spaces_quick(); 959 static void summarize_space(SpaceId id, bool maximum_compaction); 960 static void summary_phase(ParCompactionManager* cm, bool maximum_compaction); 961 962 // Adjust addresses in roots. Does not adjust addresses in heap. 963 static void adjust_roots(); 964 965 // Move objects to new locations. 966 static void compact_perm(ParCompactionManager* cm); 967 static void compact(); 968 969 // Add available regions to the stack and draining tasks to the task queue. 970 static void enqueue_region_draining_tasks(GCTaskQueue* q, 971 uint parallel_gc_threads); 972 973 // Add dense prefix update tasks to the task queue. 974 static void enqueue_dense_prefix_tasks(GCTaskQueue* q, 975 uint parallel_gc_threads); 976 977 // Add region stealing tasks to the task queue. 978 static void enqueue_region_stealing_tasks( 979 GCTaskQueue* q, 980 ParallelTaskTerminator* terminator_ptr, 981 uint parallel_gc_threads); 982 983 // If objects are left in eden after a collection, try to move the boundary 984 // and absorb them into the old gen. Returns true if eden was emptied. 985 static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 986 PSYoungGen* young_gen, 987 PSOldGen* old_gen); 988 989 // Reset time since last full gc 990 static void reset_millis_since_last_gc(); 991 992 public: 993 class MarkAndPushClosure: public OopClosure { 994 private: 995 ParCompactionManager* _compaction_manager; 996 public: 997 MarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { } 998 virtual void do_oop(oop* p); 999 virtual void do_oop(narrowOop* p); 1000 }; 1001 1002 // The one and only place to start following the classes. 1003 // Should only be applied to the ClassLoaderData klasses list. 1004 class FollowKlassClosure : public KlassClosure { 1005 private: 1006 MarkAndPushClosure* _mark_and_push_closure; 1007 public: 1008 FollowKlassClosure(MarkAndPushClosure* mark_and_push_closure) : 1009 _mark_and_push_closure(mark_and_push_closure) { } 1010 void do_klass(Klass* klass); 1011 }; 1012 1013 PSParallelCompact(); 1014 1015 // Convenient accessor for Universe::heap(). 1016 static ParallelScavengeHeap* gc_heap() { 1017 return (ParallelScavengeHeap*)Universe::heap(); 1018 } 1019 1020 static void invoke(bool maximum_heap_compaction); 1021 static bool invoke_no_policy(bool maximum_heap_compaction); 1022 1023 static void post_initialize(); 1024 // Perform initialization for PSParallelCompact that requires 1025 // allocations. This should be called during the VM initialization 1026 // at a pointer where it would be appropriate to return a JNI_ENOMEM 1027 // in the event of a failure. 1028 static bool initialize(); 1029 1030 // Closure accessors 1031 static OopClosure* adjust_pointer_closure() { return (OopClosure*)&_adjust_pointer_closure; } 1032 static KlassClosure* adjust_klass_closure() { return (KlassClosure*)&_adjust_klass_closure; } 1033 static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; } 1034 1035 // Public accessors 1036 static elapsedTimer* accumulated_time() { return &_accumulated_time; } 1037 static unsigned int total_invocations() { return _total_invocations; } 1038 static CollectorCounters* counters() { return _counters; } 1039 1040 // Used to add tasks 1041 static GCTaskManager* const gc_task_manager(); 1042 static Klass* updated_int_array_klass_obj() { 1043 return _updated_int_array_klass_obj; 1044 } 1045 1046 // Marking support 1047 static inline bool mark_obj(oop obj); 1048 static inline bool is_marked(oop obj); 1049 // Check mark and maybe push on marking stack 1050 template <class T> static inline void mark_and_push(ParCompactionManager* cm, 1051 T* p); 1052 template <class T> static inline void adjust_pointer(T* p); 1053 1054 static void follow_klass(ParCompactionManager* cm, Klass* klass); 1055 static void adjust_klass(ParCompactionManager* cm, Klass* klass); 1056 1057 static void follow_class_loader(ParCompactionManager* cm, 1058 ClassLoaderData* klass); 1059 static void adjust_class_loader(ParCompactionManager* cm, 1060 ClassLoaderData* klass); 1061 1062 // Compaction support. 1063 // Return true if p is in the range [beg_addr, end_addr). 1064 static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr); 1065 static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr); 1066 1067 // Convenience wrappers for per-space data kept in _space_info. 1068 static inline MutableSpace* space(SpaceId space_id); 1069 static inline HeapWord* new_top(SpaceId space_id); 1070 static inline HeapWord* dense_prefix(SpaceId space_id); 1071 static inline ObjectStartArray* start_array(SpaceId space_id); 1072 1073 // Move and update the live objects in the specified space. 1074 static void move_and_update(ParCompactionManager* cm, SpaceId space_id); 1075 1076 // Process the end of the given region range in the dense prefix. 1077 // This includes saving any object not updated. 1078 static void dense_prefix_regions_epilogue(ParCompactionManager* cm, 1079 size_t region_start_index, 1080 size_t region_end_index, 1081 idx_t exiting_object_offset, 1082 idx_t region_offset_start, 1083 idx_t region_offset_end); 1084 1085 // Update a region in the dense prefix. For each live object 1086 // in the region, update it's interior references. For each 1087 // dead object, fill it with deadwood. Dead space at the end 1088 // of a region range will be filled to the start of the next 1089 // live object regardless of the region_index_end. None of the 1090 // objects in the dense prefix move and dead space is dead 1091 // (holds only dead objects that don't need any processing), so 1092 // dead space can be filled in any order. 1093 static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 1094 SpaceId space_id, 1095 size_t region_index_start, 1096 size_t region_index_end); 1097 1098 // Return the address of the count + 1st live word in the range [beg, end). 1099 static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count); 1100 1101 // Return the address of the word to be copied to dest_addr, which must be 1102 // aligned to a region boundary. 1103 static HeapWord* first_src_addr(HeapWord* const dest_addr, 1104 SpaceId src_space_id, 1105 size_t src_region_idx); 1106 1107 // Determine the next source region, set closure.source() to the start of the 1108 // new region return the region index. Parameter end_addr is the address one 1109 // beyond the end of source range just processed. If necessary, switch to a 1110 // new source space and set src_space_id (in-out parameter) and src_space_top 1111 // (out parameter) accordingly. 1112 static size_t next_src_region(MoveAndUpdateClosure& closure, 1113 SpaceId& src_space_id, 1114 HeapWord*& src_space_top, 1115 HeapWord* end_addr); 1116 1117 // Decrement the destination count for each non-empty source region in the 1118 // range [beg_region, region(region_align_up(end_addr))). If the destination 1119 // count for a region goes to 0 and it needs to be filled, enqueue it. 1120 static void decrement_destination_counts(ParCompactionManager* cm, 1121 SpaceId src_space_id, 1122 size_t beg_region, 1123 HeapWord* end_addr); 1124 1125 // Fill a region, copying objects from one or more source regions. 1126 static void fill_region(ParCompactionManager* cm, size_t region_idx); 1127 static void fill_and_update_region(ParCompactionManager* cm, size_t region) { 1128 fill_region(cm, region); 1129 } 1130 1131 // Update the deferred objects in the space. 1132 static void update_deferred_objects(ParCompactionManager* cm, SpaceId id); 1133 1134 static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; } 1135 static ParallelCompactData& summary_data() { return _summary_data; } 1136 1137 // Reference Processing 1138 static ReferenceProcessor* const ref_processor() { return _ref_processor; } 1139 1140 // Return the SpaceId for the given address. 1141 static SpaceId space_id(HeapWord* addr); 1142 1143 // Time since last full gc (in milliseconds). 1144 static jlong millis_since_last_gc(); 1145 1146 static void print_on_error(outputStream* st); 1147 1148 #ifndef PRODUCT 1149 // Debugging support. 1150 static const char* space_names[last_space_id]; 1151 static void print_region_ranges(); 1152 static void print_dense_prefix_stats(const char* const algorithm, 1153 const SpaceId id, 1154 const bool maximum_compaction, 1155 HeapWord* const addr); 1156 static void summary_phase_msg(SpaceId dst_space_id, 1157 HeapWord* dst_beg, HeapWord* dst_end, 1158 SpaceId src_space_id, 1159 HeapWord* src_beg, HeapWord* src_end); 1160 #endif // #ifndef PRODUCT 1161 1162 #ifdef ASSERT 1163 // Sanity check the new location of a word in the heap. 1164 static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr); 1165 // Verify that all the regions have been emptied. 1166 static void verify_complete(SpaceId space_id); 1167 #endif // #ifdef ASSERT 1168 }; 1169 1170 inline bool PSParallelCompact::mark_obj(oop obj) { 1171 const int obj_size = obj->size(); 1172 if (mark_bitmap()->mark_obj(obj, obj_size)) { 1173 _summary_data.add_obj(obj, obj_size); 1174 return true; 1175 } else { 1176 return false; 1177 } 1178 } 1179 1180 inline bool PSParallelCompact::is_marked(oop obj) { 1181 return mark_bitmap()->is_marked(obj); 1182 } 1183 1184 template <class T> 1185 inline void PSParallelCompact::follow_root(ParCompactionManager* cm, T* p) { 1186 assert(!Universe::heap()->is_in_reserved(p), 1187 "roots shouldn't be things within the heap"); 1188 1189 T heap_oop = oopDesc::load_heap_oop(p); 1190 if (!oopDesc::is_null(heap_oop)) { 1191 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 1192 if (mark_bitmap()->is_unmarked(obj)) { 1193 if (mark_obj(obj)) { 1194 obj->follow_contents(cm); 1195 } 1196 } 1197 } 1198 cm->follow_marking_stacks(); 1199 } 1200 1201 template <class T> 1202 inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, T* p) { 1203 T heap_oop = oopDesc::load_heap_oop(p); 1204 if (!oopDesc::is_null(heap_oop)) { 1205 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 1206 if (mark_bitmap()->is_unmarked(obj) && mark_obj(obj)) { 1207 cm->push(obj); 1208 } 1209 } 1210 } 1211 1212 template <class T> 1213 inline void PSParallelCompact::adjust_pointer(T* p) { 1214 T heap_oop = oopDesc::load_heap_oop(p); 1215 if (!oopDesc::is_null(heap_oop)) { 1216 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 1217 oop new_obj = (oop)summary_data().calc_new_pointer(obj); 1218 assert(new_obj != NULL, // is forwarding ptr? 1219 "should be forwarded"); 1220 // Just always do the update unconditionally? 1221 if (new_obj != NULL) { 1222 assert(Universe::heap()->is_in_reserved(new_obj), 1223 "should be in object space"); 1224 oopDesc::encode_store_heap_oop_not_null(p, new_obj); 1225 } 1226 } 1227 } 1228 1229 template <class T> 1230 inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) { 1231 mark_and_push(_compaction_manager, p); 1232 } 1233 1234 inline bool PSParallelCompact::print_phases() { 1235 return _print_phases; 1236 } 1237 1238 inline double PSParallelCompact::normal_distribution(double density) { 1239 assert(_dwl_initialized, "uninitialized"); 1240 const double squared_term = (density - _dwl_mean) / _dwl_std_dev; 1241 return _dwl_first_term * exp(-0.5 * squared_term * squared_term); 1242 } 1243 1244 inline bool 1245 PSParallelCompact::dead_space_crosses_boundary(const RegionData* region, 1246 idx_t bit) 1247 { 1248 assert(bit > 0, "cannot call this for the first bit/region"); 1249 assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit), 1250 "sanity check"); 1251 1252 // Dead space crosses the boundary if (1) a partial object does not extend 1253 // onto the region, (2) an object does not start at the beginning of the 1254 // region, and (3) an object does not end at the end of the prior region. 1255 return region->partial_obj_size() == 0 && 1256 !_mark_bitmap.is_obj_beg(bit) && 1257 !_mark_bitmap.is_obj_end(bit - 1); 1258 } 1259 1260 inline bool 1261 PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) { 1262 return p >= beg_addr && p < end_addr; 1263 } 1264 1265 inline bool 1266 PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) { 1267 return is_in((HeapWord*)p, beg_addr, end_addr); 1268 } 1269 1270 inline MutableSpace* PSParallelCompact::space(SpaceId id) { 1271 assert(id < last_space_id, "id out of range"); 1272 return _space_info[id].space(); 1273 } 1274 1275 inline HeapWord* PSParallelCompact::new_top(SpaceId id) { 1276 assert(id < last_space_id, "id out of range"); 1277 return _space_info[id].new_top(); 1278 } 1279 1280 inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) { 1281 assert(id < last_space_id, "id out of range"); 1282 return _space_info[id].dense_prefix(); 1283 } 1284 1285 inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) { 1286 assert(id < last_space_id, "id out of range"); 1287 return _space_info[id].start_array(); 1288 } 1289 1290 #ifdef ASSERT 1291 inline void 1292 PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr) 1293 { 1294 assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr), 1295 "must move left or to a different space"); 1296 assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr), 1297 "checking alignment"); 1298 } 1299 #endif // ASSERT 1300 1301 class MoveAndUpdateClosure: public ParMarkBitMapClosure { 1302 public: 1303 inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm, 1304 ObjectStartArray* start_array, 1305 HeapWord* destination, size_t words); 1306 1307 // Accessors. 1308 HeapWord* destination() const { return _destination; } 1309 1310 // If the object will fit (size <= words_remaining()), copy it to the current 1311 // destination, update the interior oops and the start array and return either 1312 // full (if the closure is full) or incomplete. If the object will not fit, 1313 // return would_overflow. 1314 virtual IterationStatus do_addr(HeapWord* addr, size_t size); 1315 1316 // Copy enough words to fill this closure, starting at source(). Interior 1317 // oops and the start array are not updated. Return full. 1318 IterationStatus copy_until_full(); 1319 1320 // Copy enough words to fill this closure or to the end of an object, 1321 // whichever is smaller, starting at source(). Interior oops and the start 1322 // array are not updated. 1323 void copy_partial_obj(); 1324 1325 protected: 1326 // Update variables to indicate that word_count words were processed. 1327 inline void update_state(size_t word_count); 1328 1329 protected: 1330 ObjectStartArray* const _start_array; 1331 HeapWord* _destination; // Next addr to be written. 1332 }; 1333 1334 inline 1335 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap, 1336 ParCompactionManager* cm, 1337 ObjectStartArray* start_array, 1338 HeapWord* destination, 1339 size_t words) : 1340 ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array) 1341 { 1342 _destination = destination; 1343 } 1344 1345 inline void MoveAndUpdateClosure::update_state(size_t words) 1346 { 1347 decrement_words_remaining(words); 1348 _source += words; 1349 _destination += words; 1350 } 1351 1352 class UpdateOnlyClosure: public ParMarkBitMapClosure { 1353 private: 1354 const PSParallelCompact::SpaceId _space_id; 1355 ObjectStartArray* const _start_array; 1356 1357 public: 1358 UpdateOnlyClosure(ParMarkBitMap* mbm, 1359 ParCompactionManager* cm, 1360 PSParallelCompact::SpaceId space_id); 1361 1362 // Update the object. 1363 virtual IterationStatus do_addr(HeapWord* addr, size_t words); 1364 1365 inline void do_addr(HeapWord* addr); 1366 }; 1367 1368 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) 1369 { 1370 _start_array->allocate_block(addr); 1371 oop(addr)->update_contents(compaction_manager()); 1372 } 1373 1374 class FillClosure: public ParMarkBitMapClosure 1375 { 1376 public: 1377 FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : 1378 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), 1379 _start_array(PSParallelCompact::start_array(space_id)) 1380 { 1381 assert(space_id == PSParallelCompact::old_space_id, 1382 "cannot use FillClosure in the young gen"); 1383 } 1384 1385 virtual IterationStatus do_addr(HeapWord* addr, size_t size) { 1386 CollectedHeap::fill_with_objects(addr, size); 1387 HeapWord* const end = addr + size; 1388 do { 1389 _start_array->allocate_block(addr); 1390 addr += oop(addr)->size(); 1391 } while (addr < end); 1392 return ParMarkBitMap::incomplete; 1393 } 1394 1395 private: 1396 ObjectStartArray* const _start_array; 1397 }; 1398 1399 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP