1 /*
2 * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved.
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_SHENANDOAHHEAP_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
26
27 #include "gc_implementation/shared/markBitMap.hpp"
28 #include "gc_implementation/shenandoah/shenandoahAsserts.hpp"
29 #include "gc_implementation/shenandoah/shenandoahAllocRequest.hpp"
30 #include "gc_implementation/shenandoah/shenandoahLock.hpp"
31 #include "gc_implementation/shenandoah/shenandoahEvacOOMHandler.hpp"
32 #include "gc_implementation/shenandoah/shenandoahSharedVariables.hpp"
33
34 class ConcurrentGCTimer;
35
36 class ShenandoahAllocTracker;
37 class ShenandoahCollectionSet;
38 class ShenandoahCollectorPolicy;
39 class ShenandoahConcurrentMark;
40 class ShenandoahControlThread;
41 class ShenandoahGCSession;
42 class ShenandoahFreeSet;
43 class ShenandoahHeapRegion;
44 class ShenandoahHeapRegionClosure;
45 class ShenandoahMarkCompact;
46 class ShenandoahMonitoringSupport;
47 class ShenandoahHeuristics;
48 class ShenandoahMarkingContext;
49 class ShenandoahMode;
50 class ShenandoahPhaseTimings;
51 class ShenandoahPacer;
52 class ShenandoahVerifier;
53 class ShenandoahWorkGang;
54 class VMStructs;
55
56 class ShenandoahRegionIterator : public StackObj {
57 private:
58 ShenandoahHeap* _heap;
59
60 char _pad0[DEFAULT_CACHE_LINE_SIZE];
61 volatile jint _index;
62 char _pad1[DEFAULT_CACHE_LINE_SIZE];
63
64 // No implicit copying: iterators should be passed by reference to capture the state
65 ShenandoahRegionIterator(const ShenandoahRegionIterator& that);
66 ShenandoahRegionIterator& operator=(const ShenandoahRegionIterator& o);
67
68 public:
69 ShenandoahRegionIterator();
70 ShenandoahRegionIterator(ShenandoahHeap* heap);
71
72 // Reset iterator to default state
73 void reset();
74
75 // Returns next region, or NULL if there are no more regions.
76 // This is multi-thread-safe.
77 inline ShenandoahHeapRegion* next();
78
79 // This is *not* MT safe. However, in the absence of multithreaded access, it
80 // can be used to determine if there is more work to do.
81 bool has_next() const;
82 };
83
84 class ShenandoahHeapRegionClosure : public StackObj {
85 public:
86 virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
87 virtual bool is_thread_safe() { return false; }
88 };
89
90 #ifdef ASSERT
91 class ShenandoahAssertToSpaceClosure : public OopClosure {
92 private:
93 template <class T>
94 void do_oop_nv(T* p);
95 public:
96 void do_oop(narrowOop* p);
97 void do_oop(oop* p);
98 };
99 #endif
100
101 typedef ShenandoahLock ShenandoahHeapLock;
102 typedef ShenandoahLocker ShenandoahHeapLocker;
103
104 // Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
105 // to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
106 // See ShenandoahControlThread for GC cycle structure.
107 //
108 class ShenandoahHeap : public SharedHeap {
109 friend class ShenandoahAsserts;
110 friend class VMStructs;
111 friend class ShenandoahGCSession;
112
113 // ---------- Locks that guard important data structures in Heap
114 //
115 private:
116 ShenandoahHeapLock _lock;
117
118 public:
119 ShenandoahHeapLock* lock() {
120 return &_lock;
121 }
122
123 void assert_heaplock_owned_by_current_thread() NOT_DEBUG_RETURN;
124 void assert_heaplock_not_owned_by_current_thread() NOT_DEBUG_RETURN;
125 void assert_heaplock_or_safepoint() NOT_DEBUG_RETURN;
126
127 // ---------- Initialization, termination, identification, printing routines
128 //
129 public:
130 static ShenandoahHeap* heap();
131 static ShenandoahHeap* heap_no_check();
132 static size_t conservative_max_heap_alignment();
133
134 const char* name() const { return "Shenandoah"; }
135 ShenandoahHeap::Name kind() const { return CollectedHeap::ShenandoahHeap; }
136
137 ShenandoahHeap(ShenandoahCollectorPolicy* policy);
138 jint initialize();
139 void post_initialize();
140 void initialize_heuristics();
141
142 void print_on(outputStream* st) const;
143 void print_extended_on(outputStream *st) const;
144 void print_tracing_info() const;
145 void print_gc_threads_on(outputStream* st) const;
146 void print_heap_regions_on(outputStream* st) const;
147
148 void stop();
149
150 void prepare_for_verify();
151 void verify(bool silent, VerifyOption vo);
152
153 // ---------- Heap counters and metrics
154 //
155 private:
156 size_t _initial_size;
157 size_t _minimum_size;
158 char _pad0[DEFAULT_CACHE_LINE_SIZE];
159 volatile jlong _used;
160 volatile size_t _committed;
161 volatile jlong _bytes_allocated_since_gc_start;
162 char _pad1[DEFAULT_CACHE_LINE_SIZE];
163
164 public:
165 void increase_used(size_t bytes);
166 void decrease_used(size_t bytes);
167 void set_used(size_t bytes);
168
169 void increase_committed(size_t bytes);
170 void decrease_committed(size_t bytes);
171 void increase_allocated(size_t bytes);
172
173 size_t bytes_allocated_since_gc_start();
174 void reset_bytes_allocated_since_gc_start();
175
176 size_t min_capacity() const;
177 size_t max_capacity() const;
178 size_t initial_capacity() const;
179 size_t capacity() const;
180 size_t used() const;
181 size_t committed() const;
182
183 // ---------- Workers handling
184 //
185 private:
186 uint _max_workers;
187
188 public:
189 uint max_workers();
190 void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
191
192 ShenandoahWorkGang* workers() const;
193
194 void gc_threads_do(ThreadClosure* tcl) const;
195
196 // ---------- Heap regions handling machinery
197 //
198 private:
199 MemRegion _heap_region;
200 bool _heap_region_special;
201 size_t _num_regions;
202 ShenandoahHeapRegion** _regions;
203 ShenandoahRegionIterator _update_refs_iterator;
204
205 public:
206 inline size_t num_regions() const { return _num_regions; }
207 inline bool is_heap_region_special() { return _heap_region_special; }
208
209 inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
210 inline size_t heap_region_index_containing(const void* addr) const;
211
212 inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
213
214 void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
215 void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
216
217 // ---------- GC state machinery
218 //
219 // GC state describes the important parts of collector state, that may be
220 // used to make barrier selection decisions in the native and generated code.
221 // Multiple bits can be set at once.
222 //
223 // Important invariant: when GC state is zero, the heap is stable, and no barriers
224 // are required.
225 //
226 public:
227 enum GCStateBitPos {
228 // Heap has forwarded objects: need RB, ACMP, CAS barriers.
229 HAS_FORWARDED_BITPOS = 0,
230
231 // Heap is under marking: needs SATB barriers.
232 MARKING_BITPOS = 1,
233
234 // Heap is under evacuation: needs WB barriers. (Set together with UNSTABLE)
235 EVACUATION_BITPOS = 2,
236
237 // Heap is under updating: needs SVRB/SVWB barriers.
238 UPDATEREFS_BITPOS = 3
239 };
240
241 enum GCState {
242 STABLE = 0,
243 HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
244 MARKING = 1 << MARKING_BITPOS,
245 EVACUATION = 1 << EVACUATION_BITPOS,
246 UPDATEREFS = 1 << UPDATEREFS_BITPOS
247 };
248
249 private:
250 ShenandoahSharedBitmap _gc_state;
251 ShenandoahSharedFlag _degenerated_gc_in_progress;
252 ShenandoahSharedFlag _full_gc_in_progress;
253 ShenandoahSharedFlag _full_gc_move_in_progress;
254 ShenandoahSharedFlag _progress_last_gc;
255
256 void set_gc_state_mask(uint mask, bool value);
257
258 public:
259 char gc_state();
260 static address gc_state_addr();
261
262 void set_concurrent_mark_in_progress(bool in_progress);
263 void set_evacuation_in_progress(bool in_progress);
264 void set_update_refs_in_progress(bool in_progress);
265 void set_degenerated_gc_in_progress(bool in_progress);
266 void set_full_gc_in_progress(bool in_progress);
267 void set_full_gc_move_in_progress(bool in_progress);
268 void set_has_forwarded_objects(bool cond);
269
270 inline bool is_stable() const;
271 inline bool is_idle() const;
272 inline bool is_concurrent_mark_in_progress() const;
273 inline bool is_update_refs_in_progress() const;
274 inline bool is_evacuation_in_progress() const;
275 inline bool is_degenerated_gc_in_progress() const;
276 inline bool is_full_gc_in_progress() const;
277 inline bool is_full_gc_move_in_progress() const;
278 inline bool has_forwarded_objects() const;
279 inline bool is_gc_in_progress_mask(uint mask) const;
280
281 // ---------- GC cancellation and degeneration machinery
282 //
283 // Cancelled GC flag is used to notify concurrent phases that they should terminate.
284 //
285 public:
286 enum ShenandoahDegenPoint {
287 _degenerated_unset,
288 _degenerated_outside_cycle,
289 _degenerated_mark,
290 _degenerated_evac,
291 _degenerated_updaterefs,
292 _DEGENERATED_LIMIT
293 };
294
295 static const char* degen_point_to_string(ShenandoahDegenPoint point) {
296 switch (point) {
297 case _degenerated_unset:
298 return "<UNSET>";
299 case _degenerated_outside_cycle:
300 return "Outside of Cycle";
301 case _degenerated_mark:
302 return "Mark";
303 case _degenerated_evac:
304 return "Evacuation";
305 case _degenerated_updaterefs:
306 return "Update Refs";
307 default:
308 ShouldNotReachHere();
309 return "ERROR";
310 }
311 };
312
313 private:
314 ShenandoahSharedFlag _cancelled_gc;
315 inline bool try_cancel_gc();
316
317 public:
318 static address cancelled_gc_addr();
319
320 inline bool cancelled_gc() const;
321
322 inline void clear_cancelled_gc();
323
324 void cancel_gc(GCCause::Cause cause);
325
326 // ---------- GC operations entry points
327 //
328 public:
329 // Entry points to STW GC operations, these cause a related safepoint, that then
330 // call the entry method below
331 void vmop_entry_init_mark();
332 void vmop_entry_final_mark();
333 void vmop_entry_final_evac();
334 void vmop_entry_init_updaterefs();
335 void vmop_entry_final_updaterefs();
336 void vmop_entry_full(GCCause::Cause cause);
337 void vmop_degenerated(ShenandoahDegenPoint point);
338
339 // Entry methods to normally STW GC operations. These set up logging, monitoring
340 // and workers for net VM operation
341 void entry_init_mark();
342 void entry_final_mark();
343 void entry_final_evac();
344 void entry_init_updaterefs();
345 void entry_final_updaterefs();
346 void entry_full(GCCause::Cause cause);
347 void entry_degenerated(int point);
348
349 // Entry methods to normally concurrent GC operations. These set up logging, monitoring
350 // for concurrent operation.
351 void entry_reset();
352 void entry_mark();
353 void entry_preclean();
354 void entry_cleanup();
355 void entry_evac();
356 void entry_updaterefs();
357 void entry_uncommit(double shrink_before);
358
359 private:
360 // Actual work for the phases
361 void op_init_mark();
362 void op_final_mark();
363 void op_final_evac();
364 void op_init_updaterefs();
365 void op_final_updaterefs();
366 void op_full(GCCause::Cause cause);
367 void op_degenerated(ShenandoahDegenPoint point);
368 void op_degenerated_fail();
369 void op_degenerated_futile();
370
371 void op_reset();
372 void op_mark();
373 void op_preclean();
374 void op_cleanup();
375 void op_conc_evac();
376 void op_stw_evac();
377 void op_updaterefs();
378 void op_uncommit(double shrink_before);
379
380 // Messages for GC trace event, they have to be immortal for
381 // passing around the logging/tracing systems
382 const char* init_mark_event_message() const;
383 const char* final_mark_event_message() const;
384 const char* conc_mark_event_message() const;
385 const char* degen_event_message(ShenandoahDegenPoint point) const;
386
387 // ---------- GC subsystems
388 //
389 private:
390 ShenandoahControlThread* _control_thread;
391 ShenandoahCollectorPolicy* _shenandoah_policy;
392 ShenandoahMode* _gc_mode;
393 ShenandoahHeuristics* _heuristics;
394 ShenandoahFreeSet* _free_set;
395 ShenandoahConcurrentMark* _scm;
396 ShenandoahMarkCompact* _full_gc;
397 ShenandoahPacer* _pacer;
398 ShenandoahVerifier* _verifier;
399
400 ShenandoahAllocTracker* _alloc_tracker;
401 ShenandoahPhaseTimings* _phase_timings;
402
403 ShenandoahControlThread* control_thread() { return _control_thread; }
404 ShenandoahMarkCompact* full_gc() { return _full_gc; }
405
406 public:
407 ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
408 ShenandoahHeuristics* heuristics() const { return _heuristics; }
409 ShenandoahFreeSet* free_set() const { return _free_set; }
410 ShenandoahConcurrentMark* concurrent_mark() { return _scm; }
411 ShenandoahPacer* pacer() const { return _pacer; }
412
413 ShenandoahPhaseTimings* phase_timings() const { return _phase_timings; }
414 ShenandoahAllocTracker* alloc_tracker() const { return _alloc_tracker; }
415
416 ShenandoahVerifier* verifier();
417
418 // ---------- VM subsystem bindings
419 //
420 private:
421 ShenandoahMonitoringSupport* _monitoring_support;
422 ConcurrentGCTimer* _gc_timer;
423
424 public:
425 ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support; }
426
427 GCTracer* tracer();
428 GCTimer* gc_timer() const;
429 CollectorPolicy* collector_policy() const;
430
431 // ---------- Reference processing
432 //
433 private:
434 ReferenceProcessor* _ref_processor;
435 ShenandoahSharedFlag _process_references;
436
437 void ref_processing_init();
438
439 public:
440 ReferenceProcessor* ref_processor() { return _ref_processor;}
441 void set_process_references(bool pr);
442 bool process_references() const;
443
444 // ---------- Class Unloading
445 //
446 private:
447 ShenandoahSharedFlag _unload_classes;
448
449 public:
450 void set_unload_classes(bool uc);
451 bool unload_classes() const;
452
453 // Delete entries for dead interned string and clean up unreferenced symbols
454 // in symbol table, possibly in parallel.
455 void unload_classes_and_cleanup_tables(bool full_gc);
456
457 // ---------- Generic interface hooks
458 // Minor things that super-interface expects us to implement to play nice with
459 // the rest of runtime. Some of the things here are not required to be implemented,
460 // and can be stubbed out.
461 //
462 public:
463 AdaptiveSizePolicy* size_policy() shenandoah_not_implemented_return(NULL);
464 bool is_maximal_no_gc() const shenandoah_not_implemented_return(false);
465
466 bool is_in(const void* p) const;
467
468 // All objects can potentially move
469 bool is_scavengable(const void* addr) { return true; }
470
471 void collect(GCCause::Cause cause);
472 void do_full_collection(bool clear_all_soft_refs);
473
474 // Used for parsing heap during error printing
475 HeapWord* block_start(const void* addr) const;
476 size_t block_size(const HeapWord* addr) const;
477 bool block_is_obj(const HeapWord* addr) const;
478
479 // Used for native heap walkers: heap dumpers, mostly
480 void object_iterate(ObjectClosure* cl);
481 void safe_object_iterate(ObjectClosure* cl);
482 void space_iterate(SpaceClosure* scl);
483 void oop_iterate(ExtendedOopClosure* cl);
484 Space* space_containing(const void* oop) const;
485
486 // Used by RMI
487 jlong millis_since_last_gc();
488
489 bool can_elide_tlab_store_barriers() const { return true; }
490 oop new_store_pre_barrier(JavaThread* thread, oop new_obj) { return new_obj; }
491 bool can_elide_initializing_store_barrier(oop new_obj) { return true; }
492 bool card_mark_must_follow_store() const { return false; }
493
494 bool is_in_partial_collection(const void* p) shenandoah_not_implemented_return(false);
495 bool supports_heap_inspection() const { return true; }
496
497 void gc_prologue(bool b);
498 void gc_epilogue(bool b);
499
500 void acquire_pending_refs_lock();
501 void release_pending_refs_lock();
502
503 // ---------- Code roots handling hooks
504 //
505 public:
506 void register_nmethod(nmethod* nm);
507 void unregister_nmethod(nmethod* nm);
508
509 // ---------- Pinning hooks
510 //
511 public:
512 // Shenandoah supports per-object (per-region) pinning
513 bool supports_object_pinning() const { return true; }
514
515 oop pin_object(JavaThread* thread, oop obj);
516 void unpin_object(JavaThread* thread, oop obj);
517
518 void sync_pinned_region_status();
519 void assert_pinned_region_status() NOT_DEBUG_RETURN;
520
521 // ---------- Allocation support
522 //
523 private:
524 HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
525 inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
526 HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
527 HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
528
529 public:
530 HeapWord* allocate_memory(ShenandoahAllocRequest& request);
531 HeapWord* mem_allocate(size_t size, bool* what);
532
533 void notify_mutator_alloc_words(size_t words, bool waste);
534
535 // Shenandoah supports TLAB allocation
536 bool supports_tlab_allocation() const { return true; }
537
538 HeapWord* allocate_new_tlab(size_t word_size);
539 size_t tlab_capacity(Thread *thr) const;
540 size_t unsafe_max_tlab_alloc(Thread *thread) const;
541 size_t max_tlab_size() const;
542 size_t tlab_used(Thread* ignored) const;
543
544 void resize_tlabs();
545 void resize_all_tlabs();
546
547 void accumulate_statistics_tlabs();
548 void accumulate_statistics_all_gclabs();
549
550 void make_parsable(bool retire_tlabs);
551 void ensure_parsability(bool retire_tlabs);
552
553 // ---------- Marking support
554 //
555 private:
556 ShenandoahMarkingContext* _marking_context;
557 MemRegion _bitmap_region;
558 MemRegion _aux_bitmap_region;
559 MarkBitMap _verification_bit_map;
560 MarkBitMap _aux_bit_map;
561
562 size_t _bitmap_size;
563 size_t _bitmap_regions_per_slice;
564 size_t _bitmap_bytes_per_slice;
565
566 bool _bitmap_region_special;
567 bool _aux_bitmap_region_special;
568
569 // Used for buffering per-region liveness data.
570 // Needed since ShenandoahHeapRegion uses atomics to update liveness.
571 //
572 // The array has max-workers elements, each of which is an array of
573 // jushort * max_regions. The choice of jushort is not accidental:
574 // there is a tradeoff between static/dynamic footprint that translates
575 // into cache pressure (which is already high during marking), and
576 // too many atomic updates. size_t/jint is too large, jbyte is too small.
577 jushort** _liveness_cache;
578
579 public:
580 inline ShenandoahMarkingContext* complete_marking_context() const;
581 inline ShenandoahMarkingContext* marking_context() const;
582 inline void mark_complete_marking_context();
583 inline void mark_incomplete_marking_context();
584
585 template<class T>
586 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
587
588 template<class T>
589 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
590
591 template<class T>
592 inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
593
594 void reset_mark_bitmap();
595
596 // SATB barriers hooks
597 inline bool requires_marking(const void* entry) const;
598 void force_satb_flush_all_threads();
599
600 // Support for bitmap uncommits
601 bool commit_bitmap_slice(ShenandoahHeapRegion *r);
602 bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
603 bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
604
605 // Liveness caching support
606 jushort* get_liveness_cache(uint worker_id);
607 void flush_liveness_cache(uint worker_id);
608
609 // ---------- Evacuation support
610 //
611 private:
612 ShenandoahCollectionSet* _collection_set;
613 ShenandoahEvacOOMHandler _oom_evac_handler;
614
615 void evacuate_and_update_roots();
616
617 public:
618 static address in_cset_fast_test_addr();
619
620 ShenandoahCollectionSet* collection_set() const { return _collection_set; }
621
622 template <class T>
623 inline bool in_collection_set(T obj) const;
624
625 // Avoid accidentally calling the method above with ShenandoahHeapRegion*, which would be *wrong*.
626 inline bool in_collection_set(ShenandoahHeapRegion* r) shenandoah_not_implemented_return(false);
627
628 // Evacuates object src. Returns the evacuated object, either evacuated
629 // by this thread, or by some other thread.
630 inline oop evacuate_object(oop src, Thread* thread);
631
632 // Call before/after evacuation.
633 void enter_evacuation();
634 void leave_evacuation();
635
636 // ---------- Helper functions
637 //
638 public:
639 template <class T>
640 inline oop maybe_update_with_forwarded(T* p);
641
642 template <class T>
643 inline oop maybe_update_with_forwarded_not_null(T* p, oop obj);
644
645 template <class T>
646 inline oop update_with_forwarded_not_null(T* p, oop obj);
647
648 static inline oop cas_oop(oop n, narrowOop* addr, oop c);
649 static inline oop cas_oop(oop n, oop* addr, oop c);
650
651 void trash_humongous_region_at(ShenandoahHeapRegion *r);
652
653 void stop_concurrent_marking();
654
655 void roots_iterate(OopClosure* cl);
656
657 private:
658 void trash_cset_regions();
659 void update_heap_references(bool concurrent);
660
661 // ---------- Testing helpers functions
662 //
663 private:
664 ShenandoahSharedFlag _inject_alloc_failure;
665
666 void try_inject_alloc_failure();
667 bool should_inject_alloc_failure();
668 };
669
670 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP