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24 
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
27 
28 #include "gc/shared/spaceDecorator.hpp"
29 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
30 #include "gc/shenandoah/shenandoahAsserts.hpp"
31 #include "gc/shenandoah/shenandoahHeap.hpp"
32 #include "gc/shenandoah/shenandoahPacer.hpp"
33 #include "gc/shenandoah/shenandoahPadding.hpp"
34 #include "utilities/sizes.hpp"
35 
36 class VMStructs;
37 class ShenandoahHeapRegionStateConstant;
38 
39 class ShenandoahHeapRegion {
40   friend class VMStructs;
41   friend class ShenandoahHeapRegionStateConstant;
42 private:
43   /*
44     Region state is described by a state machine. Transitions are guarded by
45     heap lock, which allows changing the state of several regions atomically.
46     Region states can be logically aggregated in groups.
47 
48       "Empty":
49       .................................................................
50       .                                                               .
51       .                                                               .
52       .         Uncommitted  <-------  Committed <------------------------\
53       .              |                     |                          .   |
54       .              \---------v-----------/                          .   |
55       .                        |                                      .   |
56       .........................|.......................................   |
57                                |                                          |
58       "Active":                |                                          |
59       .........................|.......................................   |
60       .                        |                                      .   |
61       .      /-----------------^-------------------\                  .   |
62       .      |                                     |                  .   |
63       .      v                                     v    "Humongous":  .   |
64       .   Regular ---\-----\     ..................O................  .   |
65       .     |  ^     |     |     .                 |               .  .   |
66       .     |  |     |     |     .                 *---------\     .  .   |
67       .     v  |     |     |     .                 v         v     .  .   |
68       .    Pinned  Cset    |     .  HStart <--> H/Start   H/Cont   .  .   |
69       .       ^    / |     |     .  Pinned         v         |     .  .   |
70       .       |   /  |     |     .                 *<--------/     .  .   |
71       .       |  v   |     |     .                 |               .  .   |
72       .  CsetPinned  |     |     ..................O................  .   |
73       .              |     |                       |                  .   |
74       .              \-----\---v-------------------/                  .   |
75       .                        |                                      .   |
76       .........................|.......................................   |
77                                |                                          |
78       "Trash":                 |                                          |
79       .........................|.......................................   |
80       .                        |                                      .   |
81       .                        v                                      .   |
82       .                      Trash ---------------------------------------/
83       .                                                               .
84       .                                                               .
85       .................................................................
86 
87     Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
88     to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
89 
90     Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
91     and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
92     quick reclamation without actual cleaning up.
93 
94     Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
95     Can be done asynchronously and in bulk.
96 
97     Note how internal transitions disallow logic bugs:
98       a) No region can go Empty, unless properly reclaimed/recycled;
99       b) No region can go Uncommitted, unless reclaimed/recycled first;
100       c) Only Regular regions can go to CSet;
101       d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
102       e) Pinned cannot go CSet, thus it never moves;
103       f) Humongous cannot be used for regular allocations;
104       g) Humongous cannot go CSet, thus it never moves;
105       h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
106          follow associated humongous starts, not pinnable/movable by themselves);
107       i) Empty cannot go Trash, avoiding useless work;
108       j) ...
109    */
110 
111   enum RegionState {
112     _empty_uncommitted,       // region is empty and has memory uncommitted
113     _empty_committed,         // region is empty and has memory committed
114     _regular,                 // region is for regular allocations
115     _humongous_start,         // region is the humongous start
116     _humongous_cont,          // region is the humongous continuation
117     _pinned_humongous_start,  // region is both humongous start and pinned
118     _cset,                    // region is in collection set
119     _pinned,                  // region is pinned
120     _pinned_cset,             // region is pinned and in cset (evac failure path)
121     _trash,                   // region contains only trash
122     _REGION_STATES_NUM        // last
123   };
124 
region_state_to_string(RegionState s)125   static const char* region_state_to_string(RegionState s) {
126     switch (s) {
127       case _empty_uncommitted:       return "Empty Uncommitted";
128       case _empty_committed:         return "Empty Committed";
129       case _regular:                 return "Regular";
130       case _humongous_start:         return "Humongous Start";
131       case _humongous_cont:          return "Humongous Continuation";
132       case _pinned_humongous_start:  return "Humongous Start, Pinned";
133       case _cset:                    return "Collection Set";
134       case _pinned:                  return "Pinned";
135       case _pinned_cset:             return "Collection Set, Pinned";
136       case _trash:                   return "Trash";
137       default:
138         ShouldNotReachHere();
139         return "";
140     }
141   }
142 
143   // This method protects from accidental changes in enum order:
region_state_to_ordinal(RegionState s) const144   int region_state_to_ordinal(RegionState s) const {
145     switch (s) {
146       case _empty_uncommitted:      return 0;
147       case _empty_committed:        return 1;
148       case _regular:                return 2;
149       case _humongous_start:        return 3;
150       case _humongous_cont:         return 4;
151       case _cset:                   return 5;
152       case _pinned:                 return 6;
153       case _trash:                  return 7;
154       case _pinned_cset:            return 8;
155       case _pinned_humongous_start: return 9;
156       default:
157         ShouldNotReachHere();
158         return -1;
159     }
160   }
161 
162   void report_illegal_transition(const char* method);
163 
164 public:
region_states_num()165   static const int region_states_num() {
166     return _REGION_STATES_NUM;
167   }
168 
169   // Allowed transitions from the outside code:
170   void make_regular_allocation();
171   void make_regular_bypass();
172   void make_humongous_start();
173   void make_humongous_cont();
174   void make_humongous_start_bypass();
175   void make_humongous_cont_bypass();
176   void make_pinned();
177   void make_unpinned();
178   void make_cset();
179   void make_trash();
180   void make_trash_immediate();
181   void make_empty();
182   void make_uncommitted();
183   void make_committed_bypass();
184 
185   // Individual states:
is_empty_uncommitted() const186   bool is_empty_uncommitted()      const { return _state == _empty_uncommitted; }
is_empty_committed() const187   bool is_empty_committed()        const { return _state == _empty_committed; }
is_regular() const188   bool is_regular()                const { return _state == _regular; }
is_humongous_continuation() const189   bool is_humongous_continuation() const { return _state == _humongous_cont; }
190 
191   // Participation in logical groups:
is_empty() const192   bool is_empty()                  const { return is_empty_committed() || is_empty_uncommitted(); }
is_active() const193   bool is_active()                 const { return !is_empty() && !is_trash(); }
is_trash() const194   bool is_trash()                  const { return _state == _trash; }
is_humongous_start() const195   bool is_humongous_start()        const { return _state == _humongous_start || _state == _pinned_humongous_start; }
is_humongous() const196   bool is_humongous()              const { return is_humongous_start() || is_humongous_continuation(); }
is_committed() const197   bool is_committed()              const { return !is_empty_uncommitted(); }
is_cset() const198   bool is_cset()                   const { return _state == _cset   || _state == _pinned_cset; }
is_pinned() const199   bool is_pinned()                 const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
200 
201   // Macro-properties:
is_alloc_allowed() const202   bool is_alloc_allowed()          const { return is_empty() || is_regular() || _state == _pinned; }
is_stw_move_allowed() const203   bool is_stw_move_allowed()       const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
204 
state() const205   RegionState state()              const { return _state; }
state_ordinal() const206   int  state_ordinal()             const { return region_state_to_ordinal(_state); }
207 
208   void record_pin();
209   void record_unpin();
210   size_t pin_count() const;
211 
212 private:
213   static size_t RegionCount;
214   static size_t RegionSizeBytes;
215   static size_t RegionSizeWords;
216   static size_t RegionSizeBytesShift;
217   static size_t RegionSizeWordsShift;
218   static size_t RegionSizeBytesMask;
219   static size_t RegionSizeWordsMask;
220   static size_t HumongousThresholdBytes;
221   static size_t HumongousThresholdWords;
222   static size_t MaxTLABSizeBytes;
223   static size_t MaxTLABSizeWords;
224 
225   // Never updated fields
226   size_t const _index;
227   HeapWord* const _bottom;
228   HeapWord* const _end;
229 
230   // Rarely updated fields
231   HeapWord* _new_top;
232   double _empty_time;
233 
234   // Seldom updated fields
235   RegionState _state;
236 
237   // Frequently updated fields
238   HeapWord* _top;
239 
240   size_t _tlab_allocs;
241   size_t _gclab_allocs;
242 
243   volatile size_t _live_data;
244   volatile size_t _critical_pins;
245 
246   HeapWord* volatile _update_watermark;
247 
248 public:
249   ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
250 
251   static const size_t MIN_NUM_REGIONS = 10;
252 
253   static void setup_sizes(size_t max_heap_size);
254 
empty_time()255   double empty_time() {
256     return _empty_time;
257   }
258 
required_regions(size_t bytes)259   inline static size_t required_regions(size_t bytes) {
260     return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
261   }
262 
region_count()263   inline static size_t region_count() {
264     return ShenandoahHeapRegion::RegionCount;
265   }
266 
region_size_bytes()267   inline static size_t region_size_bytes() {
268     return ShenandoahHeapRegion::RegionSizeBytes;
269   }
270 
region_size_words()271   inline static size_t region_size_words() {
272     return ShenandoahHeapRegion::RegionSizeWords;
273   }
274 
region_size_bytes_shift()275   inline static size_t region_size_bytes_shift() {
276     return ShenandoahHeapRegion::RegionSizeBytesShift;
277   }
278 
region_size_words_shift()279   inline static size_t region_size_words_shift() {
280     return ShenandoahHeapRegion::RegionSizeWordsShift;
281   }
282 
region_size_bytes_mask()283   inline static size_t region_size_bytes_mask() {
284     return ShenandoahHeapRegion::RegionSizeBytesMask;
285   }
286 
region_size_words_mask()287   inline static size_t region_size_words_mask() {
288     return ShenandoahHeapRegion::RegionSizeWordsMask;
289   }
290 
291   // Convert to jint with sanity checking
region_size_bytes_jint()292   inline static jint region_size_bytes_jint() {
293     assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
294     return (jint)ShenandoahHeapRegion::RegionSizeBytes;
295   }
296 
297   // Convert to jint with sanity checking
region_size_words_jint()298   inline static jint region_size_words_jint() {
299     assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
300     return (jint)ShenandoahHeapRegion::RegionSizeWords;
301   }
302 
303   // Convert to jint with sanity checking
region_size_bytes_shift_jint()304   inline static jint region_size_bytes_shift_jint() {
305     assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
306     return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
307   }
308 
309   // Convert to jint with sanity checking
region_size_words_shift_jint()310   inline static jint region_size_words_shift_jint() {
311     assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
312     return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
313   }
314 
humongous_threshold_bytes()315   inline static size_t humongous_threshold_bytes() {
316     return ShenandoahHeapRegion::HumongousThresholdBytes;
317   }
318 
humongous_threshold_words()319   inline static size_t humongous_threshold_words() {
320     return ShenandoahHeapRegion::HumongousThresholdWords;
321   }
322 
max_tlab_size_bytes()323   inline static size_t max_tlab_size_bytes() {
324     return ShenandoahHeapRegion::MaxTLABSizeBytes;
325   }
326 
max_tlab_size_words()327   inline static size_t max_tlab_size_words() {
328     return ShenandoahHeapRegion::MaxTLABSizeWords;
329   }
330 
index() const331   inline size_t index() const {
332     return _index;
333   }
334 
335   // Allocation (return NULL if full)
336   inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
337 
338   inline void clear_live_data();
339   void set_live_data(size_t s);
340 
341   // Increase live data for newly allocated region
342   inline void increase_live_data_alloc_words(size_t s);
343 
344   // Increase live data for region scanned with GC
345   inline void increase_live_data_gc_words(size_t s);
346 
347   inline bool has_live() const;
348   inline size_t get_live_data_bytes() const;
349   inline size_t get_live_data_words() const;
350 
351   inline size_t garbage() const;
352 
353   void print_on(outputStream* st) const;
354 
355   void recycle();
356 
357   void oop_iterate(OopIterateClosure* cl);
358 
359   HeapWord* block_start(const void* p) const;
360   size_t block_size(const HeapWord* p) const;
block_is_obj(const HeapWord * p) const361   bool block_is_obj(const HeapWord* p) const { return p < top(); }
362 
363   // Find humongous start region that this region belongs to
364   ShenandoahHeapRegion* humongous_start_region() const;
365 
top() const366   HeapWord* top() const         { return _top;     }
set_top(HeapWord * v)367   void set_top(HeapWord* v)     { _top = v;        }
368 
new_top() const369   HeapWord* new_top() const     { return _new_top; }
set_new_top(HeapWord * v)370   void set_new_top(HeapWord* v) { _new_top = v;    }
371 
bottom() const372   HeapWord* bottom() const      { return _bottom;  }
end() const373   HeapWord* end() const         { return _end;     }
374 
capacity() const375   size_t capacity() const       { return byte_size(bottom(), end()); }
used() const376   size_t used() const           { return byte_size(bottom(), top()); }
free() const377   size_t free() const           { return byte_size(top(),    end()); }
378 
379   inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
380   void reset_alloc_metadata();
381   size_t get_shared_allocs() const;
382   size_t get_tlab_allocs() const;
383   size_t get_gclab_allocs() const;
384 
385   inline HeapWord* get_update_watermark() const;
386   inline void set_update_watermark(HeapWord* w);
387   inline void set_update_watermark_at_safepoint(HeapWord* w);
388 
389 private:
390   void do_commit();
391   void do_uncommit();
392 
393   void oop_iterate_objects(OopIterateClosure* cl);
394   void oop_iterate_humongous(OopIterateClosure* cl);
395 
396   inline void internal_increase_live_data(size_t s);
397 
398   void set_state(RegionState to);
399 };
400 
401 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
402