1 /*
  2  * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
  3  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
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 25 
 26 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
 27 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
 28 
 29 #include "gc/shared/gc_globals.hpp"
 30 #include "gc/shared/spaceDecorator.hpp"
 31 #include "gc/shenandoah/shenandoahAffiliation.hpp"
 32 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
 33 #include "gc/shenandoah/shenandoahAsserts.hpp"
 34 #include "gc/shenandoah/shenandoahHeap.hpp"
 35 #include "gc/shenandoah/shenandoahPacer.hpp"
 36 #include "gc/shenandoah/shenandoahPadding.hpp"
 37 #include "utilities/sizes.hpp"
 38 
 39 class VMStructs;
 40 class ShenandoahHeapRegionStateConstant;
 41 
 42 class ShenandoahHeapRegion {
 43   friend class VMStructs;
 44   friend class ShenandoahHeapRegionStateConstant;
 45 private:
 46   /*
 47     Region state is described by a state machine. Transitions are guarded by
 48     heap lock, which allows changing the state of several regions atomically.
 49     Region states can be logically aggregated in groups.
 50 
 51       "Empty":
 52       .................................................................
 53       .                                                               .
 54       .                                                               .
 55       .         Uncommitted  <-------  Committed <------------------------\
 56       .              |                     |                          .   |
 57       .              \---------v-----------/                          .   |
 58       .                        |                                      .   |
 59       .........................|.......................................   |
 60                                |                                          |
 61       "Active":                |                                          |
 62       .........................|.......................................   |
 63       .                        |                                      .   |
 64       .      /-----------------^-------------------\                  .   |
 65       .      |                                     |                  .   |
 66       .      v                                     v    "Humongous":  .   |
 67       .   Regular ---\-----\     ..................O................  .   |
 68       .     |  ^     |     |     .                 |               .  .   |
 69       .     |  |     |     |     .                 *---------\     .  .   |
 70       .     v  |     |     |     .                 v         v     .  .   |
 71       .    Pinned  Cset    |     .  HStart <--> H/Start   H/Cont   .  .   |
 72       .       ^    / |     |     .  Pinned         v         |     .  .   |
 73       .       |   /  |     |     .                 *<--------/     .  .   |
 74       .       |  v   |     |     .                 |               .  .   |
 75       .  CsetPinned  |     |     ..................O................  .   |
 76       .              |     |                       |                  .   |
 77       .              \-----\---v-------------------/                  .   |
 78       .                        |                                      .   |
 79       .........................|.......................................   |
 80                                |                                          |
 81       "Trash":                 |                                          |
 82       .........................|.......................................   |
 83       .                        |                                      .   |
 84       .                        v                                      .   |
 85       .                      Trash ---------------------------------------/
 86       .                                                               .
 87       .                                                               .
 88       .................................................................
 89 
 90     Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
 91     to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
 92 
 93     Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
 94     and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
 95     quick reclamation without actual cleaning up.
 96 
 97     Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
 98     Can be done asynchronously and in bulk.
 99 
100     Note how internal transitions disallow logic bugs:
101       a) No region can go Empty, unless properly reclaimed/recycled;
102       b) No region can go Uncommitted, unless reclaimed/recycled first;
103       c) Only Regular regions can go to CSet;
104       d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
105       e) Pinned cannot go CSet, thus it never moves;
106       f) Humongous cannot be used for regular allocations;
107       g) Humongous cannot go CSet, thus it never moves;
108       h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
109          follow associated humongous starts, not pinnable/movable by themselves);
110       i) Empty cannot go Trash, avoiding useless work;
111       j) ...
112    */
113 
114   enum RegionState {
115     _empty_uncommitted,       // region is empty and has memory uncommitted
116     _empty_committed,         // region is empty and has memory committed
117     _regular,                 // region is for regular allocations
118     _humongous_start,         // region is the humongous start
119     _humongous_cont,          // region is the humongous continuation
120     _pinned_humongous_start,  // region is both humongous start and pinned
121     _cset,                    // region is in collection set
122     _pinned,                  // region is pinned
123     _pinned_cset,             // region is pinned and in cset (evac failure path)
124     _trash,                   // region contains only trash
125     _REGION_STATES_NUM        // last
126   };
127 
128   static const char* region_state_to_string(RegionState s) {
129     switch (s) {
130       case _empty_uncommitted:       return "Empty Uncommitted";
131       case _empty_committed:         return "Empty Committed";
132       case _regular:                 return "Regular";
133       case _humongous_start:         return "Humongous Start";
134       case _humongous_cont:          return "Humongous Continuation";
135       case _pinned_humongous_start:  return "Humongous Start, Pinned";
136       case _cset:                    return "Collection Set";
137       case _pinned:                  return "Pinned";
138       case _pinned_cset:             return "Collection Set, Pinned";
139       case _trash:                   return "Trash";
140       default:
141         ShouldNotReachHere();
142         return "";
143     }
144   }
145 
146   // This method protects from accidental changes in enum order:
147   int region_state_to_ordinal(RegionState s) const {
148     switch (s) {
149       case _empty_uncommitted:      return 0;
150       case _empty_committed:        return 1;
151       case _regular:                return 2;
152       case _humongous_start:        return 3;
153       case _humongous_cont:         return 4;
154       case _cset:                   return 5;
155       case _pinned:                 return 6;
156       case _trash:                  return 7;
157       case _pinned_cset:            return 8;
158       case _pinned_humongous_start: return 9;
159       default:
160         ShouldNotReachHere();
161         return -1;
162     }
163   }
164 
165   void report_illegal_transition(const char* method);
166 
167 public:
168   static int region_states_num() {
169     return _REGION_STATES_NUM;
170   }
171 
172   // Allowed transitions from the outside code:
173   void make_regular_allocation(ShenandoahAffiliation affiliation);
174   void make_young_maybe();
175   void make_regular_bypass();
176   void make_humongous_start();
177   void make_humongous_cont();
178   void make_humongous_start_bypass(ShenandoahAffiliation affiliation);
179   void make_humongous_cont_bypass(ShenandoahAffiliation affiliation);
180   void make_pinned();
181   void make_unpinned();
182   void make_cset();
183   void make_trash();
184   void make_trash_immediate();
185   void make_empty();
186   void make_uncommitted();
187   void make_committed_bypass();
188 
189   // Individual states:
190   bool is_empty_uncommitted()      const { return _state == _empty_uncommitted; }
191   bool is_empty_committed()        const { return _state == _empty_committed; }
192   bool is_regular()                const { return _state == _regular; }
193   bool is_humongous_continuation() const { return _state == _humongous_cont; }
194 
195   // Participation in logical groups:
196   bool is_empty()                  const { return is_empty_committed() || is_empty_uncommitted(); }
197   bool is_active()                 const { return !is_empty() && !is_trash(); }
198   bool is_trash()                  const { return _state == _trash; }
199   bool is_humongous_start()        const { return _state == _humongous_start || _state == _pinned_humongous_start; }
200   bool is_humongous()              const { return is_humongous_start() || is_humongous_continuation(); }
201   bool is_committed()              const { return !is_empty_uncommitted(); }
202   bool is_cset()                   const { return _state == _cset   || _state == _pinned_cset; }
203   bool is_pinned()                 const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
204   inline bool is_young() const;
205   inline bool is_old() const;
206   inline bool is_affiliated() const;
207 
208   // Macro-properties:
209   bool is_alloc_allowed()          const { return is_empty() || is_regular() || _state == _pinned; }
210   bool is_stw_move_allowed()       const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
211 
212   RegionState state()              const { return _state; }
213   int  state_ordinal()             const { return region_state_to_ordinal(_state); }
214 
215   void record_pin();
216   void record_unpin();
217   size_t pin_count() const;
218 
219 private:
220   static size_t RegionCount;
221   static size_t RegionSizeBytes;
222   static size_t RegionSizeWords;
223   static size_t RegionSizeBytesShift;
224   static size_t RegionSizeWordsShift;
225   static size_t RegionSizeBytesMask;
226   static size_t RegionSizeWordsMask;
227   static size_t HumongousThresholdBytes;
228   static size_t HumongousThresholdWords;
229   static size_t MaxTLABSizeBytes;
230   static size_t MaxTLABSizeWords;
231 
232   // Never updated fields
233   size_t const _index;
234   HeapWord* const _bottom;
235   HeapWord* const _end;
236 
237   // Rarely updated fields
238   HeapWord* _new_top;
239   double _empty_time;
240 
241   HeapWord* _top_before_promoted;
242 
243   // Seldom updated fields
244   RegionState _state;
245   HeapWord* _coalesce_and_fill_boundary; // for old regions not selected as collection set candidates.
246 
247   // Frequently updated fields
248   HeapWord* _top;
249 
250   size_t _tlab_allocs;
251   size_t _gclab_allocs;
252   size_t _plab_allocs;
253 
254   volatile size_t _live_data;
255   volatile size_t _critical_pins;
256 
257   HeapWord* volatile _update_watermark;
258 
259   uint _age;
260   CENSUS_NOISE(uint _youth;)   // tracks epochs of retrograde ageing (rejuvenation)
261 
262 public:
263   ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
264 
265   static const size_t MIN_NUM_REGIONS = 10;
266 
267   // Return adjusted max heap size
268   static size_t setup_sizes(size_t max_heap_size);
269 
270   double empty_time() {
271     return _empty_time;
272   }
273 
274   inline static size_t required_regions(size_t bytes) {
275     return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
276   }
277 
278   inline static size_t region_count() {
279     return ShenandoahHeapRegion::RegionCount;
280   }
281 
282   inline static size_t region_size_bytes() {
283     return ShenandoahHeapRegion::RegionSizeBytes;
284   }
285 
286   inline static size_t region_size_words() {
287     return ShenandoahHeapRegion::RegionSizeWords;
288   }
289 
290   inline static size_t region_size_bytes_shift() {
291     return ShenandoahHeapRegion::RegionSizeBytesShift;
292   }
293 
294   inline static size_t region_size_words_shift() {
295     return ShenandoahHeapRegion::RegionSizeWordsShift;
296   }
297 
298   inline static size_t region_size_bytes_mask() {
299     return ShenandoahHeapRegion::RegionSizeBytesMask;
300   }
301 
302   inline static size_t region_size_words_mask() {
303     return ShenandoahHeapRegion::RegionSizeWordsMask;
304   }
305 
306   // Convert to jint with sanity checking
307   inline static jint region_size_bytes_jint() {
308     assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
309     return (jint)ShenandoahHeapRegion::RegionSizeBytes;
310   }
311 
312   // Convert to jint with sanity checking
313   inline static jint region_size_words_jint() {
314     assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
315     return (jint)ShenandoahHeapRegion::RegionSizeWords;
316   }
317 
318   // Convert to jint with sanity checking
319   inline static jint region_size_bytes_shift_jint() {
320     assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
321     return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
322   }
323 
324   // Convert to jint with sanity checking
325   inline static jint region_size_words_shift_jint() {
326     assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
327     return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
328   }
329 
330   inline static size_t humongous_threshold_bytes() {
331     return ShenandoahHeapRegion::HumongousThresholdBytes;
332   }
333 
334   inline static size_t humongous_threshold_words() {
335     return ShenandoahHeapRegion::HumongousThresholdWords;
336   }
337 
338   inline static size_t max_tlab_size_bytes() {
339     return ShenandoahHeapRegion::MaxTLABSizeBytes;
340   }
341 
342   inline static size_t max_tlab_size_words() {
343     return ShenandoahHeapRegion::MaxTLABSizeWords;
344   }
345 
346   inline size_t index() const {
347     return _index;
348   }
349 
350   inline void save_top_before_promote();
351   inline HeapWord* get_top_before_promote() const { return _top_before_promoted; }
352   inline void restore_top_before_promote();
353   inline size_t garbage_before_padded_for_promote() const;
354 
355   // Allocation (return nullptr if full)
356   inline HeapWord* allocate_aligned(size_t word_size, ShenandoahAllocRequest &req, size_t alignment_in_words);
357 
358   // Allocation (return nullptr if full)
359   inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest req);
360 
361   inline void clear_live_data();
362   void set_live_data(size_t s);
363 
364   // Increase live data for newly allocated region
365   inline void increase_live_data_alloc_words(size_t s);
366 
367   // Increase live data for region scanned with GC
368   inline void increase_live_data_gc_words(size_t s);
369 
370   inline bool has_live() const;
371   inline size_t get_live_data_bytes() const;
372   inline size_t get_live_data_words() const;
373 
374   inline size_t garbage() const;
375 
376   void print_on(outputStream* st) const;
377 
378   void recycle();
379 
380   inline void begin_preemptible_coalesce_and_fill() {
381     _coalesce_and_fill_boundary = _bottom;
382   }
383 
384   inline void end_preemptible_coalesce_and_fill() {
385     _coalesce_and_fill_boundary = _end;
386   }
387 
388   inline void suspend_coalesce_and_fill(HeapWord* next_focus) {
389     _coalesce_and_fill_boundary = next_focus;
390   }
391 
392   inline HeapWord* resume_coalesce_and_fill() {
393     return _coalesce_and_fill_boundary;
394   }
395 
396   // Coalesce contiguous spans of garbage objects by filling header and reregistering start locations with remembered set.
397   // This is used by old-gen GC following concurrent marking to make old-gen HeapRegions parsable.  Return true iff
398   // region is completely coalesced and filled.  Returns false if cancelled before task is complete.
399   bool oop_fill_and_coalesce();
400 
401   // Like oop_fill_and_coalesce(), but without honoring cancellation requests.
402   bool oop_fill_and_coalesce_without_cancel();
403 
404   // During global collections, this service iterates through an old-gen heap region that is not part of collection
405   // set to fill and register ranges of dead memory.  Note that live objects were previously registered.  Some dead objects
406   // that are subsumed into coalesced ranges of dead memory need to be "unregistered".
407   void global_oop_iterate_and_fill_dead(OopIterateClosure* cl);
408   void oop_iterate_humongous(OopIterateClosure* cl);
409   void oop_iterate_humongous(OopIterateClosure* cl, HeapWord* start, size_t words);
410 
411   // Invoke closure on every reference contained within the humongous object that spans this humongous
412   // region if the reference is contained within a DIRTY card and the reference is no more than words following
413   // start within the humongous object.
414   void oop_iterate_humongous_slice(OopIterateClosure* cl, bool dirty_only, HeapWord* start, size_t words, bool write_table);
415 
416   HeapWord* block_start(const void* p) const;
417   size_t block_size(const HeapWord* p) const;
418   bool block_is_obj(const HeapWord* p) const { return p < top(); }
419 
420   // Find humongous start region that this region belongs to
421   ShenandoahHeapRegion* humongous_start_region() const;
422 
423   HeapWord* top() const         { return _top;     }
424   void set_top(HeapWord* v)     { _top = v;        }
425 
426   HeapWord* new_top() const     { return _new_top; }
427   void set_new_top(HeapWord* v) { _new_top = v;    }
428 
429   HeapWord* bottom() const      { return _bottom;  }
430   HeapWord* end() const         { return _end;     }
431 
432   size_t capacity() const       { return byte_size(bottom(), end()); }
433   size_t used() const           { return byte_size(bottom(), top()); }
434   size_t used_before_promote() const { return byte_size(bottom(), get_top_before_promote()); }
435   size_t free() const           { return byte_size(top(),    end()); }
436 
437   // Does this region contain this address?
438   bool contains(HeapWord* p) const {
439     return (bottom() <= p) && (p < top());
440   }
441 
442   inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
443   void reset_alloc_metadata();
444   size_t get_shared_allocs() const;
445   size_t get_tlab_allocs() const;
446   size_t get_gclab_allocs() const;
447   size_t get_plab_allocs() const;
448 
449   inline HeapWord* get_update_watermark() const;
450   inline void set_update_watermark(HeapWord* w);
451   inline void set_update_watermark_at_safepoint(HeapWord* w);
452 
453   inline ShenandoahAffiliation affiliation() const;
454   inline const char* affiliation_name() const;
455 
456   void set_affiliation(ShenandoahAffiliation new_affiliation);
457 
458   // Region ageing and rejuvenation
459   uint age() { return _age; }
460   CENSUS_NOISE(uint youth() { return _youth; })
461 
462   void increment_age() {
463     const uint max_age = markWord::max_age;
464     assert(_age <= max_age, "Error");
465     if (_age++ >= max_age) {
466       _age = max_age;   // clamp
467     }
468   }
469 
470   void reset_age() {
471     CENSUS_NOISE(_youth += _age;)
472     _age = 0;
473   }
474 
475   CENSUS_NOISE(void clear_youth() { _youth = 0; })
476 
477   // Register all objects.  Set all remembered set cards to dirty.
478   void promote_humongous();
479   void promote_in_place();
480 
481 private:
482   void decrement_humongous_waste() const;
483   void do_commit();
484   void do_uncommit();
485 
486   // This is an old-region that was not part of the collection set during a GLOBAL collection.  We coalesce the dead
487   // objects, but do not need to register the live objects as they are already registered.
488   void global_oop_iterate_objects_and_fill_dead(OopIterateClosure* cl);
489 
490   inline void internal_increase_live_data(size_t s);
491 
492   void set_state(RegionState to);
493 };
494 
495 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP