1 /*
  2  * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact 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_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
 26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
 27 
 28 #include "gc/shared/gc_globals.hpp"
 29 #include "gc/shared/spaceDecorator.hpp"
 30 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
 31 #include "gc/shenandoah/shenandoahAsserts.hpp"
 32 #include "gc/shenandoah/shenandoahHeap.hpp"
 33 #include "gc/shenandoah/shenandoahPacer.hpp"
 34 #include "gc/shenandoah/shenandoahPadding.hpp"
 35 #include "utilities/sizes.hpp"
 36 
 37 class VMStructs;
 38 class ShenandoahHeapRegionStateConstant;
 39 
 40 class ShenandoahHeapRegion {
 41   friend class VMStructs;
 42   friend class ShenandoahHeapRegionStateConstant;
 43 private:
 44   /*
 45     Region state is described by a state machine. Transitions are guarded by
 46     heap lock, which allows changing the state of several regions atomically.
 47     Region states can be logically aggregated in groups.
 48 
 49       "Empty":
 50       .................................................................
 51       .                                                               .
 52       .                                                               .
 53       .         Uncommitted  <-------  Committed <------------------------\
 54       .              |                     |                          .   |
 55       .              \---------v-----------/                          .   |
 56       .                        |                                      .   |
 57       .........................|.......................................   |
 58                                |                                          |
 59       "Active":                |                                          |
 60       .........................|.......................................   |
 61       .                        |                                      .   |
 62       .      /-----------------^-------------------\                  .   |
 63       .      |                                     |                  .   |
 64       .      v                                     v    "Humongous":  .   |
 65       .   Regular ---\-----\     ..................O................  .   |
 66       .     |  ^     |     |     .                 |               .  .   |
 67       .     |  |     |     |     .                 *---------\     .  .   |
 68       .     v  |     |     |     .                 v         v     .  .   |
 69       .    Pinned  Cset    |     .  HStart <--> H/Start   H/Cont   .  .   |
 70       .       ^    / |     |     .  Pinned         v         |     .  .   |
 71       .       |   /  |     |     .                 *<--------/     .  .   |
 72       .       |  v   |     |     .                 |               .  .   |
 73       .  CsetPinned  |     |     ..................O................  .   |
 74       .              |     |                       |                  .   |
 75       .              \-----\---v-------------------/                  .   |
 76       .                        |                                      .   |
 77       .........................|.......................................   |
 78                                |                                          |
 79       "Trash":                 |                                          |
 80       .........................|.......................................   |
 81       .                        |                                      .   |
 82       .                        v                                      .   |
 83       .                      Trash ---------------------------------------/
 84       .                                                               .
 85       .                                                               .
 86       .................................................................
 87 
 88     Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
 89     to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
 90 
 91     Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
 92     and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
 93     quick reclamation without actual cleaning up.
 94 
 95     Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
 96     Can be done asynchronously and in bulk.
 97 
 98     Note how internal transitions disallow logic bugs:
 99       a) No region can go Empty, unless properly reclaimed/recycled;
100       b) No region can go Uncommitted, unless reclaimed/recycled first;
101       c) Only Regular regions can go to CSet;
102       d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
103       e) Pinned cannot go CSet, thus it never moves;
104       f) Humongous cannot be used for regular allocations;
105       g) Humongous cannot go CSet, thus it never moves;
106       h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
107          follow associated humongous starts, not pinnable/movable by themselves);
108       i) Empty cannot go Trash, avoiding useless work;
109       j) ...
110    */
111 
112   enum RegionState {
113     _empty_uncommitted,       // region is empty and has memory uncommitted
114     _empty_committed,         // region is empty and has memory committed
115     _regular,                 // region is for regular allocations
116     _humongous_start,         // region is the humongous start
117     _humongous_cont,          // region is the humongous continuation
118     _pinned_humongous_start,  // region is both humongous start and pinned
119     _cset,                    // region is in collection set
120     _pinned,                  // region is pinned
121     _pinned_cset,             // region is pinned and in cset (evac failure path)
122     _trash,                   // region contains only trash
123     _REGION_STATES_NUM        // last
124   };
125 
126   static const char* region_state_to_string(RegionState s) {
127     switch (s) {
128       case _empty_uncommitted:       return "Empty Uncommitted";
129       case _empty_committed:         return "Empty Committed";
130       case _regular:                 return "Regular";
131       case _humongous_start:         return "Humongous Start";
132       case _humongous_cont:          return "Humongous Continuation";
133       case _pinned_humongous_start:  return "Humongous Start, Pinned";
134       case _cset:                    return "Collection Set";
135       case _pinned:                  return "Pinned";
136       case _pinned_cset:             return "Collection Set, Pinned";
137       case _trash:                   return "Trash";
138       default:
139         ShouldNotReachHere();
140         return "";
141     }
142   }
143 
144   // This method protects from accidental changes in enum order:
145   int region_state_to_ordinal(RegionState s) const {
146     switch (s) {
147       case _empty_uncommitted:      return 0;
148       case _empty_committed:        return 1;
149       case _regular:                return 2;
150       case _humongous_start:        return 3;
151       case _humongous_cont:         return 4;
152       case _cset:                   return 5;
153       case _pinned:                 return 6;
154       case _trash:                  return 7;
155       case _pinned_cset:            return 8;
156       case _pinned_humongous_start: return 9;
157       default:
158         ShouldNotReachHere();
159         return -1;
160     }
161   }
162 
163   void report_illegal_transition(const char* method);
164 
165 public:
166   static const int region_states_num() {
167     return _REGION_STATES_NUM;
168   }
169 
170   // Allowed transitions from the outside code:
171   void make_regular_allocation();
172   void make_regular_bypass();
173   void make_humongous_start();
174   void make_humongous_cont();
175   void make_humongous_start_bypass();
176   void make_humongous_cont_bypass();
177   void make_pinned();
178   void make_unpinned();
179   void make_cset();
180   void make_trash();
181   void make_trash_immediate();
182   void make_empty();
183   void make_uncommitted();
184   void make_committed_bypass();
185 
186   // Individual states:
187   bool is_empty_uncommitted()      const { return _state == _empty_uncommitted; }
188   bool is_empty_committed()        const { return _state == _empty_committed; }
189   bool is_regular()                const { return _state == _regular; }
190   bool is_humongous_continuation() const { return _state == _humongous_cont; }
191 
192   // Participation in logical groups:
193   bool is_empty()                  const { return is_empty_committed() || is_empty_uncommitted(); }
194   bool is_active()                 const { return !is_empty() && !is_trash(); }
195   bool is_trash()                  const { return _state == _trash; }
196   bool is_humongous_start()        const { return _state == _humongous_start || _state == _pinned_humongous_start; }
197   bool is_humongous()              const { return is_humongous_start() || is_humongous_continuation(); }
198   bool is_committed()              const { return !is_empty_uncommitted(); }
199   bool is_cset()                   const { return _state == _cset   || _state == _pinned_cset; }
200   bool is_pinned()                 const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
201 
202   // Macro-properties:
203   bool is_alloc_allowed()          const { return is_empty() || is_regular() || _state == _pinned; }
204   bool is_stw_move_allowed()       const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
205 
206   RegionState state()              const { return _state; }
207   int  state_ordinal()             const { return region_state_to_ordinal(_state); }
208 
209   void record_pin();
210   void record_unpin();
211   size_t pin_count() const;
212 
213 private:
214   static size_t RegionCount;
215   static size_t RegionSizeBytes;
216   static size_t RegionSizeWords;
217   static size_t RegionSizeBytesShift;
218   static size_t RegionSizeWordsShift;
219   static size_t RegionSizeBytesMask;
220   static size_t RegionSizeWordsMask;
221   static size_t HumongousThresholdBytes;
222   static size_t HumongousThresholdWords;
223   static size_t MaxTLABSizeBytes;
224   static size_t MaxTLABSizeWords;
225 
226   // Never updated fields
227   size_t const _index;
228   HeapWord* const _bottom;
229   HeapWord* const _end;
230 
231   // Rarely updated fields
232   HeapWord* _new_top;
233   double _empty_time;
234 
235   // Seldom updated fields
236   RegionState _state;
237 
238   // Frequently updated fields
239   HeapWord* _top;
240 
241   size_t _tlab_allocs;
242   size_t _gclab_allocs;
243 
244   volatile size_t _live_data;
245   volatile size_t _critical_pins;
246 
247   HeapWord* volatile _update_watermark;
248 
249 public:
250   ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
251 
252   static const size_t MIN_NUM_REGIONS = 10;
253 
254   // Return adjusted max heap size
255   static size_t setup_sizes(size_t max_heap_size);
256 
257   double empty_time() {
258     return _empty_time;
259   }
260 
261   inline static size_t required_regions(size_t bytes) {
262     return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
263   }
264 
265   inline static size_t region_count() {
266     return ShenandoahHeapRegion::RegionCount;
267   }
268 
269   inline static size_t region_size_bytes() {
270     return ShenandoahHeapRegion::RegionSizeBytes;
271   }
272 
273   inline static size_t region_size_words() {
274     return ShenandoahHeapRegion::RegionSizeWords;
275   }
276 
277   inline static size_t region_size_bytes_shift() {
278     return ShenandoahHeapRegion::RegionSizeBytesShift;
279   }
280 
281   inline static size_t region_size_words_shift() {
282     return ShenandoahHeapRegion::RegionSizeWordsShift;
283   }
284 
285   inline static size_t region_size_bytes_mask() {
286     return ShenandoahHeapRegion::RegionSizeBytesMask;
287   }
288 
289   inline static size_t region_size_words_mask() {
290     return ShenandoahHeapRegion::RegionSizeWordsMask;
291   }
292 
293   // Convert to jint with sanity checking
294   inline static jint region_size_bytes_jint() {
295     assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
296     return (jint)ShenandoahHeapRegion::RegionSizeBytes;
297   }
298 
299   // Convert to jint with sanity checking
300   inline static jint region_size_words_jint() {
301     assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
302     return (jint)ShenandoahHeapRegion::RegionSizeWords;
303   }
304 
305   // Convert to jint with sanity checking
306   inline static jint region_size_bytes_shift_jint() {
307     assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
308     return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
309   }
310 
311   // Convert to jint with sanity checking
312   inline static jint region_size_words_shift_jint() {
313     assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
314     return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
315   }
316 
317   inline static size_t humongous_threshold_bytes() {
318     return ShenandoahHeapRegion::HumongousThresholdBytes;
319   }
320 
321   inline static size_t humongous_threshold_words() {
322     return ShenandoahHeapRegion::HumongousThresholdWords;
323   }
324 
325   inline static size_t max_tlab_size_bytes() {
326     return ShenandoahHeapRegion::MaxTLABSizeBytes;
327   }
328 
329   inline static size_t max_tlab_size_words() {
330     return ShenandoahHeapRegion::MaxTLABSizeWords;
331   }
332 
333   inline size_t index() const {
334     return _index;
335   }
336 
337   // Allocation (return NULL if full)
338   inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
339 
340   inline void clear_live_data();
341   void set_live_data(size_t s);
342 
343   // Increase live data for newly allocated region
344   inline void increase_live_data_alloc_words(size_t s);
345 
346   // Increase live data for region scanned with GC
347   inline void increase_live_data_gc_words(size_t s);
348 
349   inline bool has_live() const;
350   inline size_t get_live_data_bytes() const;
351   inline size_t get_live_data_words() const;
352 
353   inline size_t garbage() const;
354 
355   void print_on(outputStream* st) const;
356 
357   void recycle();
358 
359   void oop_iterate(OopIterateClosure* cl);
360 
361   HeapWord* block_start(const void* p) const;
362   size_t block_size(const HeapWord* p) const;
363   bool block_is_obj(const HeapWord* p) const { return p < top(); }
364 
365   // Find humongous start region that this region belongs to
366   ShenandoahHeapRegion* humongous_start_region() const;
367 
368   HeapWord* top() const         { return _top;     }
369   void set_top(HeapWord* v)     { _top = v;        }
370 
371   HeapWord* new_top() const     { return _new_top; }
372   void set_new_top(HeapWord* v) { _new_top = v;    }
373 
374   HeapWord* bottom() const      { return _bottom;  }
375   HeapWord* end() const         { return _end;     }
376 
377   size_t capacity() const       { return byte_size(bottom(), end()); }
378   size_t used() const           { return byte_size(bottom(), top()); }
379   size_t free() const           { return byte_size(top(),    end()); }
380 
381   inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
382   void reset_alloc_metadata();
383   size_t get_shared_allocs() const;
384   size_t get_tlab_allocs() const;
385   size_t get_gclab_allocs() const;
386 
387   inline HeapWord* get_update_watermark() const;
388   inline void set_update_watermark(HeapWord* w);
389   inline void set_update_watermark_at_safepoint(HeapWord* w);
390 
391 private:
392   void do_commit();
393   void do_uncommit();
394 
395   void oop_iterate_objects(OopIterateClosure* cl);
396   void oop_iterate_humongous(OopIterateClosure* cl);
397 
398   inline void internal_increase_live_data(size_t s);
399 
400   void set_state(RegionState to);
401 };
402 
403 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP