1 /*
   2  * Copyright (c) 2013, 2015, Red Hat, Inc. and/or its affiliates.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
  25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
  26 
  27 #include "gc/shared/space.hpp"
  28 #include "memory/universe.hpp"
  29 #include "utilities/sizes.hpp"
  30 
  31 class ShenandoahHeapRegion : public ContiguousSpace {
  32 private:
  33   /*
  34     Region state is described by a state machine. Transitions are guarded by
  35     heap lock, which allows changing the state of several regions atomically.
  36     Region states can be logically aggregated in groups.
  37 
  38       "Empty":
  39       ....................................................
  40       .                                                  .
  41       .                                                  .
  42       .         Uncommitted  <-------  Committed <------------\
  43       .              |                     |             .    |
  44       .              \---------v-----------/             .    |
  45       .                        |                         .    |
  46       .........................|..........................    |
  47                                |                              |
  48       "Active":                |                              |
  49       .........................|..........................    |
  50       .                        |                         .    |
  51       .      /-----------------^------\                  .    |
  52       .      |                        |                  .    |
  53       .      v                        v    "Humongous":  .    |
  54       .   Regular --\-----\      .....O................  .    |
  55       .     |  ^    |     |      .    |               .  .    |
  56       .     |  |    |     |      .    *---------\     .  .    |
  57       .     v  |    |     v      .    v         v     .  .    |
  58       .    Pinned   |    CSet    .  H/Start   H/Cont  .  .    |
  59       .             |     |      .    v         |     .  .    |
  60       .             |     |      .    *<--------/     .  .    |
  61       .             |     |      .    |               .  .    |
  62       .             |     |      .....O................  .    |
  63       .             |     |           |                  .    |
  64       .             \-----\---v-------/                  .    |
  65       .                       |                          .    |
  66       ........................|...........................    |
  67                               |                               |
  68       "Trash":                |                               |
  69       ........................|...........................    |
  70       .                       |                          .    |
  71       .                       v                          .    |
  72       .                     Trash ----------------------------/
  73       .                                                  .
  74       .                                                  .
  75       ....................................................
  76 
  77     Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
  78     to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
  79 
  80     Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
  81     and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
  82     quick reclamation without actual cleaning up.
  83 
  84     Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
  85     Can be done asynchronously and in bulk.
  86 
  87     Note how internal transitions disallow logic bugs:
  88       a) No region can go Empty, unless properly reclaimed/recycled;
  89       b) No region can go Uncommitted, unless reclaimed/recycled first;
  90       c) Only Regular regions can go to CSet;
  91       d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
  92       e) Pinned cannot go CSet, thus it never moves;
  93       f) Humongous cannot be used for regular allocations;
  94       g) Humongous cannot go CSet, thus it never moves;
  95       h) Humongous cannot go pinned, avoiding useless work;
  96       i) Empty cannot go Trash, avoiding useless work;
  97       j) ...
  98    */
  99 
 100   enum RegionState {
 101     _empty_uncommitted, // region is empty and has memory uncommitted
 102     _empty_committed,   // region is empty and has memory committed
 103     _regular,           // region is for regular allocations
 104     _humongous_start,   // region is the humongous start
 105     _humongous_cont,    // region is the humongous continuation
 106     _cset,              // region is in collection set
 107     _pinned,            // region is pinned
 108     _trash,             // region contains only trash
 109   };
 110 
 111   const char* region_state_to_string(RegionState s) const {
 112     switch (s) {
 113       case _empty_uncommitted: return "Empty Uncommitted";
 114       case _empty_committed:   return "Empty Committed";
 115       case _regular:           return "Regular";
 116       case _humongous_start:   return "Humongous Start";
 117       case _humongous_cont:    return "Humongous Continuation";
 118       case _cset:              return "Collection Set";
 119       case _pinned:            return "Pinned";
 120       case _trash:             return "Trash";
 121       default:
 122         ShouldNotReachHere();
 123         return "";
 124     }
 125   }
 126 
 127   // This method protects from accidental changes in enum order:
 128   int region_state_to_ordinal(RegionState s) const {
 129     switch (s) {
 130       case _empty_uncommitted: return 0;
 131       case _empty_committed:   return 1;
 132       case _regular:           return 2;
 133       case _humongous_start:   return 3;
 134       case _humongous_cont:    return 4;
 135       case _cset:              return 5;
 136       case _pinned:            return 6;
 137       case _trash:             return 7;
 138       default:
 139         ShouldNotReachHere();
 140         return -1;
 141     }
 142   }
 143 
 144 public:
 145   // Allowed transitions from the outside code:
 146   void make_regular_allocation();
 147   void make_regular_bypass();
 148   void make_humongous_start();
 149   void make_humongous_cont();
 150   void make_pinned();
 151   void make_unpinned();
 152   void make_cset();
 153   void make_trash();
 154   void make_empty_committed();
 155   bool make_empty_uncommitted();
 156 
 157   // Individual states:
 158   bool is_empty_uncommitted()      const { return _state == _empty_uncommitted; }
 159   bool is_empty_committed()        const { return _state == _empty_committed; }
 160   bool is_regular()                const { return _state == _regular; }
 161   bool is_humongous_start()        const { return _state == _humongous_start; }
 162   bool is_humongous_continuation() const { return _state == _humongous_cont; }
 163   bool is_cset()                   const { return _state == _cset; }
 164   bool is_pinned()                 const { return _state == _pinned; }
 165 
 166   // Participation in logical groups:
 167   bool is_empty()                  const { return is_empty_committed() || is_empty_uncommitted(); }
 168   bool is_active()                 const { return !is_empty() && !is_trash(); }
 169   bool is_trash()                  const { return _state == _trash; }
 170 
 171   // Macro-properties:
 172   bool is_humongous()              const { return is_humongous_start() || is_humongous_continuation(); }
 173   bool is_committed()              const { return !is_empty_uncommitted(); }
 174   bool is_alloc_allowed()          const { return is_empty() || is_regular() || is_pinned(); }
 175 
 176   RegionState state()              const { return _state; }
 177   int  state_ordinal()             const { return region_state_to_ordinal(_state); }
 178 
 179 private:
 180   static size_t RegionSizeBytes;
 181   static size_t RegionSizeWords;
 182   static size_t RegionSizeBytesShift;
 183   static size_t RegionSizeWordsShift;
 184   static size_t RegionSizeBytesMask;
 185   static size_t RegionSizeWordsMask;
 186   static size_t HumongousThresholdBytes;
 187   static size_t HumongousThresholdWords;
 188   static size_t MaxTLABSizeBytes;
 189 
 190   // Global alloaction counter, increased for each allocation
 191   // under Shenandoah heap lock
 192   static uint64_t AllocSeqNum;
 193 
 194   ShenandoahHeap* _heap;
 195   size_t _region_number;
 196   volatile jint _live_data;
 197   MemRegion _reserved;
 198 
 199   size_t _tlab_allocs;
 200   size_t _gclab_allocs;
 201   size_t _shared_allocs;
 202 
 203   bool _root;
 204 
 205   HeapWord* _new_top;
 206 
 207   size_t _critical_pins;
 208 
 209   // Seq numbers are used for generational and Least Recently Used heuristics.
 210   // They are set when the region is used for allocation.
 211   uint64_t  _first_alloc_seq_num;
 212   uint64_t  _last_alloc_seq_num;
 213 
 214   RegionState _state;
 215   double _empty_time;
 216 
 217 public:
 218   ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed);
 219 
 220   static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
 221 
 222   double empty_time() {
 223     return _empty_time;
 224   }
 225 
 226   inline static size_t required_regions(size_t bytes) {
 227     return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
 228   }
 229 
 230   inline static size_t region_size_bytes() {
 231     return ShenandoahHeapRegion::RegionSizeBytes;
 232   }
 233 
 234   inline static size_t region_size_words() {
 235     return ShenandoahHeapRegion::RegionSizeWords;
 236   }
 237 
 238   inline static size_t region_size_bytes_shift() {
 239     return ShenandoahHeapRegion::RegionSizeBytesShift;
 240   }
 241 
 242   inline static size_t region_size_words_shift() {
 243     return ShenandoahHeapRegion::RegionSizeWordsShift;
 244   }
 245 
 246   inline static size_t region_size_bytes_mask() {
 247     return ShenandoahHeapRegion::RegionSizeBytesMask;
 248   }
 249 
 250   inline static size_t region_size_words_mask() {
 251     return ShenandoahHeapRegion::RegionSizeWordsMask;
 252   }
 253 
 254   // Convert to jint with sanity checking
 255   inline static jint region_size_bytes_jint() {
 256     assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
 257     return (jint)ShenandoahHeapRegion::RegionSizeBytes;
 258   }
 259 
 260   // Convert to jint with sanity checking
 261   inline static jint region_size_words_jint() {
 262     assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
 263     return (jint)ShenandoahHeapRegion::RegionSizeWords;
 264   }
 265 
 266   // Convert to jint with sanity checking
 267   inline static jint region_size_bytes_shift_jint() {
 268     assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
 269     return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
 270   }
 271 
 272   // Convert to jint with sanity checking
 273   inline static jint region_size_words_shift_jint() {
 274     assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
 275     return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
 276   }
 277 
 278   inline static size_t humongous_threshold_bytes() {
 279     return ShenandoahHeapRegion::HumongousThresholdBytes;
 280   }
 281 
 282   inline static size_t humongous_threshold_words() {
 283     return ShenandoahHeapRegion::HumongousThresholdWords;
 284   }
 285 
 286   inline static size_t max_tlab_size_bytes() {
 287     return ShenandoahHeapRegion::MaxTLABSizeBytes;
 288   }
 289 
 290   static uint64_t alloc_seq_num() {
 291     // Last used seq number
 292     return AllocSeqNum - 1;
 293   }
 294 
 295   size_t region_number() const;
 296 
 297   // Allocation (return NULL if full)
 298   inline HeapWord* allocate(size_t word_size, ShenandoahHeap::AllocType type);
 299   HeapWord* allocate(size_t word_size) {
 300     // ContiguousSpace wants us to have this method. But it is an error to call this with Shenandoah.
 301     ShouldNotCallThis();
 302     return NULL;
 303   }
 304 
 305   // Roll back the previous allocation of an object with specified size.
 306   // Returns TRUE when successful, FALSE if not successful or not supported.
 307   bool rollback_allocation(uint size);
 308 
 309   void clear_live_data();
 310   void set_live_data(size_t s);
 311   inline void increase_live_data_words(size_t s);
 312   inline void increase_live_data_words(jint s);
 313 
 314   void reset_alloc_stats_to_shared();
 315   void reset_alloc_stats();
 316   size_t get_shared_allocs() const;
 317   size_t get_tlab_allocs() const;
 318   size_t get_gclab_allocs() const;
 319 
 320   bool has_live() const;
 321   size_t get_live_data_bytes() const;
 322   size_t get_live_data_words() const;
 323 
 324   void print_on(outputStream* st) const;
 325 
 326   size_t garbage() const;
 327 
 328   void recycle();
 329   void recycle_no_matrix();
 330 
 331   void oop_iterate(ExtendedOopClosure* cl);
 332 
 333   HeapWord* block_start_const(const void* p) const;
 334 
 335   // Just before GC we need to fill the current region.
 336   void fill_region();
 337 
 338   bool in_collection_set() const;
 339 
 340   // Find humongous start region that this region belongs to
 341   ShenandoahHeapRegion* humongous_start_region() const;
 342 
 343   virtual CompactibleSpace* next_compaction_space() const;
 344 
 345   // Override for scan_and_forward support.
 346   void prepare_for_compaction(CompactPoint* cp);
 347   void adjust_pointers();
 348   void compact();
 349 
 350   void set_new_top(HeapWord* new_top) { _new_top = new_top; }
 351   HeapWord* new_top() const { return _new_top; }
 352 
 353   void set_root(bool r) {
 354     _root = r;
 355   }
 356   bool is_root() const {
 357     return _root;
 358   }
 359 
 360   uint64_t first_alloc_seq_num() const {
 361     return _first_alloc_seq_num;
 362   }
 363 
 364   uint64_t last_alloc_seq_num()  const {
 365     return _last_alloc_seq_num;
 366   }
 367 
 368 private:
 369   void do_commit();
 370   void do_uncommit();
 371 
 372   void oop_iterate_objects(ExtendedOopClosure* cl);
 373   void oop_iterate_humongous(ExtendedOopClosure* cl);
 374 };
 375 
 376 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP