78 SubTasksDone* _process_strong_tasks;
79
80 // Collects the given generation.
81 void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab,
82 bool run_verification, bool clear_soft_refs,
83 bool restore_marks_for_biased_locking);
84
85 // In block contents verification, the number of header words to skip
86 NOT_PRODUCT(static size_t _skip_header_HeapWords;)
87
88 FlexibleWorkGang* _workers;
89
90 protected:
91 // Helper functions for allocation
92 HeapWord* attempt_allocation(size_t size,
93 bool is_tlab,
94 bool first_only);
95
96 // Helper function for two callbacks below.
97 // Considers collection of the first max_level+1 generations.
98 void do_collection(bool full,
99 bool clear_all_soft_refs,
100 size_t size,
101 bool is_tlab,
102 int max_level);
103
104 // Callback from VM_GenCollectForAllocation operation.
105 // This function does everything necessary/possible to satisfy an
106 // allocation request that failed in the youngest generation that should
107 // have handled it (including collection, expansion, etc.)
108 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
109
110 // Callback from VM_GenCollectFull operation.
111 // Perform a full collection of the first max_level+1 generations.
112 virtual void do_full_collection(bool clear_all_soft_refs);
113 void do_full_collection(bool clear_all_soft_refs, int max_level);
114
115 // Does the "cause" of GC indicate that
116 // we absolutely __must__ clear soft refs?
117 bool must_clear_all_soft_refs();
118
119 public:
120 GenCollectedHeap(GenCollectorPolicy *policy);
121
122 FlexibleWorkGang* workers() const { return _workers; }
123
124 GCStats* gc_stats(int level) const;
125
126 // Returns JNI_OK on success
127 virtual jint initialize();
128
129 // Reserve aligned space for the heap as needed by the contained generations.
130 char* allocate(size_t alignment, ReservedSpace* heap_rs);
131
132 // Does operations required after initialization has been done.
133 void post_initialize();
134
135 // Initialize ("weak") refs processing support
136 virtual void ref_processing_init();
137
138 virtual Name kind() const {
139 return CollectedHeap::GenCollectedHeap;
140 }
141
142 Generation* young_gen() const { return _young_gen; }
143 Generation* old_gen() const { return _old_gen; }
144
145 // The generational collector policy.
146 GenCollectorPolicy* gen_policy() const { return _gen_policy; }
147
148 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) gen_policy(); }
149
150 // Adaptive size policy
151 virtual AdaptiveSizePolicy* size_policy() {
152 return gen_policy()->size_policy();
153 }
154
155 // Return the (conservative) maximum heap alignment
156 static size_t conservative_max_heap_alignment() {
157 return Generation::GenGrain;
158 }
159
160 size_t capacity() const;
161 size_t used() const;
162
163 // Save the "used_region" for generations level and lower.
164 void save_used_regions(int level);
165
166 size_t max_capacity() const;
167
168 HeapWord* mem_allocate(size_t size,
169 bool* gc_overhead_limit_was_exceeded);
170
171 // We may support a shared contiguous allocation area, if the youngest
172 // generation does.
173 bool supports_inline_contig_alloc() const;
174 HeapWord** top_addr() const;
175 HeapWord** end_addr() const;
176
177 // Perform a full collection of the heap; intended for use in implementing
178 // "System.gc". This implies as full a collection as the CollectedHeap
179 // supports. Caller does not hold the Heap_lock on entry.
180 void collect(GCCause::Cause cause);
181
182 // The same as above but assume that the caller holds the Heap_lock.
183 void collect_locked(GCCause::Cause cause);
184
185 // Perform a full collection of the first max_level+1 generations.
186 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
187 void collect(GCCause::Cause cause, int max_level);
188
189 // Returns "TRUE" iff "p" points into the committed areas of the heap.
190 // The methods is_in(), is_in_closed_subset() and is_in_youngest() may
191 // be expensive to compute in general, so, to prevent
192 // their inadvertent use in product jvm's, we restrict their use to
193 // assertion checking or verification only.
194 bool is_in(const void* p) const;
195
196 // override
197 bool is_in_closed_subset(const void* p) const {
198 if (UseConcMarkSweepGC) {
199 return is_in_reserved(p);
200 } else {
201 return is_in(p);
202 }
203 }
204
205 // Returns true if the reference is to an object in the reserved space
206 // for the young generation.
207 // Assumes the the young gen address range is less than that of the old gen.
297
298 // Total number of full collections completed.
299 unsigned int total_full_collections_completed() {
300 assert(_full_collections_completed <= _total_full_collections,
301 "Can't complete more collections than were started");
302 return _full_collections_completed;
303 }
304
305 // Update above counter, as appropriate, at the end of a stop-world GC cycle
306 unsigned int update_full_collections_completed();
307 // Update above counter, as appropriate, at the end of a concurrent GC cycle
308 unsigned int update_full_collections_completed(unsigned int count);
309
310 // Update "time of last gc" for all generations to "now".
311 void update_time_of_last_gc(jlong now) {
312 _young_gen->update_time_of_last_gc(now);
313 _old_gen->update_time_of_last_gc(now);
314 }
315
316 // Update the gc statistics for each generation.
317 // "level" is the level of the latest collection.
318 void update_gc_stats(int current_level, bool full) {
319 _young_gen->update_gc_stats(current_level, full);
320 _old_gen->update_gc_stats(current_level, full);
321 }
322
323 bool no_gc_in_progress() { return !is_gc_active(); }
324
325 // Override.
326 void prepare_for_verify();
327
328 // Override.
329 void verify(bool silent, VerifyOption option);
330
331 // Override.
332 virtual void print_on(outputStream* st) const;
333 virtual void print_gc_threads_on(outputStream* st) const;
334 virtual void gc_threads_do(ThreadClosure* tc) const;
335 virtual void print_tracing_info() const;
336 virtual void print_on_error(outputStream* st) const;
337
338 // PrintGC, PrintGCDetails support
339 void print_heap_change(size_t prev_used) const;
340
348 };
349
350 // Apply "cl.do_generation" to all generations in the heap
351 // If "old_to_young" determines the order.
352 void generation_iterate(GenClosure* cl, bool old_to_young);
353
354 // Return "true" if all generations have reached the
355 // maximal committed limit that they can reach, without a garbage
356 // collection.
357 virtual bool is_maximal_no_gc() const;
358
359 // This function returns the "GenRemSet" object that allows us to scan
360 // generations in a fully generational heap.
361 GenRemSet* rem_set() { return _rem_set; }
362
363 // Convenience function to be used in situations where the heap type can be
364 // asserted to be this type.
365 static GenCollectedHeap* heap();
366
367 // Invoke the "do_oop" method of one of the closures "not_older_gens"
368 // or "older_gens" on root locations for the generation at
369 // "level". (The "older_gens" closure is used for scanning references
370 // from older generations; "not_older_gens" is used everywhere else.)
371 // If "younger_gens_as_roots" is false, younger generations are
372 // not scanned as roots; in this case, the caller must be arranging to
373 // scan the younger generations itself. (For example, a generation might
374 // explicitly mark reachable objects in younger generations, to avoid
375 // excess storage retention.)
376 // The "so" argument determines which of the roots
377 // the closure is applied to:
378 // "SO_None" does none;
379 enum ScanningOption {
380 SO_None = 0x0,
381 SO_AllCodeCache = 0x8,
382 SO_ScavengeCodeCache = 0x10
383 };
384
385 private:
386 void process_roots(StrongRootsScope* scope,
387 ScanningOption so,
388 OopClosure* strong_roots,
389 OopClosure* weak_roots,
390 CLDClosure* strong_cld_closure,
391 CLDClosure* weak_cld_closure,
392 CodeBlobClosure* code_roots);
393
394 public:
395 static const bool StrongAndWeakRoots = false;
396 static const bool StrongRootsOnly = true;
397
398 void gen_process_roots(StrongRootsScope* scope,
399 int level,
400 bool younger_gens_as_roots,
401 ScanningOption so,
402 bool only_strong_roots,
403 OopsInGenClosure* not_older_gens,
404 OopsInGenClosure* older_gens,
405 CLDClosure* cld_closure);
406
407 // Apply "root_closure" to all the weak roots of the system.
408 // These include JNI weak roots, string table,
409 // and referents of reachable weak refs.
410 void gen_process_weak_roots(OopClosure* root_closure);
411
412 // Set the saved marks of generations, if that makes sense.
413 // In particular, if any generation might iterate over the oops
414 // in other generations, it should call this method.
415 void save_marks();
416
417 // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects
418 // allocated since the last call to save_marks in generations at or above
419 // "level". The "cur" closure is
420 // applied to references in the generation at "level", and the "older"
421 // closure to older generations.
422 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \
423 void oop_since_save_marks_iterate(int level, \
424 OopClosureType* cur, \
425 OopClosureType* older);
426
427 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL)
428
429 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL
430
431 // Returns "true" iff no allocations have occurred in any generation at
432 // "level" or above since the last
433 // call to "save_marks".
434 bool no_allocs_since_save_marks(int level);
435
436 // Returns true if an incremental collection is likely to fail.
437 // We optionally consult the young gen, if asked to do so;
438 // otherwise we base our answer on whether the previous incremental
439 // collection attempt failed with no corrective action as of yet.
440 bool incremental_collection_will_fail(bool consult_young) {
441 // Assumes a 2-generation system; the first disjunct remembers if an
442 // incremental collection failed, even when we thought (second disjunct)
443 // that it would not.
444 assert(heap()->collector_policy()->is_generation_policy(),
445 "the following definition may not be suitable for an n(>2)-generation system");
446 return incremental_collection_failed() ||
447 (consult_young && !_young_gen->collection_attempt_is_safe());
448 }
449
450 // If a generation bails out of an incremental collection,
451 // it sets this flag.
452 bool incremental_collection_failed() const {
453 return _incremental_collection_failed;
454 }
455 void set_incremental_collection_failed() {
456 _incremental_collection_failed = true;
457 }
458 void clear_incremental_collection_failed() {
459 _incremental_collection_failed = false;
460 }
461
462 // Promotion of obj into gen failed. Try to promote obj to higher
463 // gens in ascending order; return the new location of obj if successful.
464 // Otherwise, try expand-and-allocate for obj in both the young and old
465 // generation; return the new location of obj if successful. Otherwise, return NULL.
466 oop handle_failed_promotion(Generation* old_gen,
467 oop obj,
468 size_t obj_size);
469
470 private:
471 // Accessor for memory state verification support
472 NOT_PRODUCT(
473 static size_t skip_header_HeapWords() { return _skip_header_HeapWords; }
474 )
475
476 // Override
477 void check_for_non_bad_heap_word_value(HeapWord* addr,
478 size_t size) PRODUCT_RETURN;
479
480 // For use by mark-sweep. As implemented, mark-sweep-compact is global
481 // in an essential way: compaction is performed across generations, by
482 // iterating over spaces.
483 void prepare_for_compaction();
484
485 // Perform a full collection of the first max_level+1 generations.
486 // This is the low level interface used by the public versions of
487 // collect() and collect_locked(). Caller holds the Heap_lock on entry.
488 void collect_locked(GCCause::Cause cause, int max_level);
489
490 // Returns success or failure.
491 bool create_cms_collector();
492
493 // In support of ExplicitGCInvokesConcurrent functionality
494 bool should_do_concurrent_full_gc(GCCause::Cause cause);
495 void collect_mostly_concurrent(GCCause::Cause cause);
496
497 // Save the tops of the spaces in all generations
498 void record_gen_tops_before_GC() PRODUCT_RETURN;
499
500 protected:
501 void gc_prologue(bool full);
502 void gc_epilogue(bool full);
503 };
504
505 #endif // SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP
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78 SubTasksDone* _process_strong_tasks;
79
80 // Collects the given generation.
81 void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab,
82 bool run_verification, bool clear_soft_refs,
83 bool restore_marks_for_biased_locking);
84
85 // In block contents verification, the number of header words to skip
86 NOT_PRODUCT(static size_t _skip_header_HeapWords;)
87
88 FlexibleWorkGang* _workers;
89
90 protected:
91 // Helper functions for allocation
92 HeapWord* attempt_allocation(size_t size,
93 bool is_tlab,
94 bool first_only);
95
96 // Helper function for two callbacks below.
97 // Considers collection of the first max_level+1 generations.
98 void do_collection(bool full,
99 bool clear_all_soft_refs,
100 size_t size,
101 bool is_tlab,
102 Generation::Type max_generation);
103
104 // Callback from VM_GenCollectForAllocation operation.
105 // This function does everything necessary/possible to satisfy an
106 // allocation request that failed in the youngest generation that should
107 // have handled it (including collection, expansion, etc.)
108 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
109
110 // Callback from VM_GenCollectFull operation.
111 // Perform a full collection of the first max_level+1 generations.
112 virtual void do_full_collection(bool clear_all_soft_refs);
113 void do_full_collection(bool clear_all_soft_refs, Generation::Type max_generation);
114
115 // Does the "cause" of GC indicate that
116 // we absolutely __must__ clear soft refs?
117 bool must_clear_all_soft_refs();
118
119 public:
120 GenCollectedHeap(GenCollectorPolicy *policy);
121
122 FlexibleWorkGang* workers() const { return _workers; }
123
124 GCStats* gc_stats(Generation* generation) const;
125
126 // Returns JNI_OK on success
127 virtual jint initialize();
128
129 // Reserve aligned space for the heap as needed by the contained generations.
130 char* allocate(size_t alignment, ReservedSpace* heap_rs);
131
132 // Does operations required after initialization has been done.
133 void post_initialize();
134
135 // Initialize ("weak") refs processing support
136 virtual void ref_processing_init();
137
138 virtual Name kind() const {
139 return CollectedHeap::GenCollectedHeap;
140 }
141
142 Generation* young_gen() const { return _young_gen; }
143 Generation* old_gen() const { return _old_gen; }
144
145 // The generational collector policy.
146 GenCollectorPolicy* gen_policy() const { return _gen_policy; }
147
148 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) gen_policy(); }
149
150 // Adaptive size policy
151 virtual AdaptiveSizePolicy* size_policy() {
152 return gen_policy()->size_policy();
153 }
154
155 // Return the (conservative) maximum heap alignment
156 static size_t conservative_max_heap_alignment() {
157 return Generation::GenGrain;
158 }
159
160 size_t capacity() const;
161 size_t used() const;
162
163 // Save the "used_region" for both generations.
164 void save_used_regions();
165
166 size_t max_capacity() const;
167
168 HeapWord* mem_allocate(size_t size,
169 bool* gc_overhead_limit_was_exceeded);
170
171 // We may support a shared contiguous allocation area, if the youngest
172 // generation does.
173 bool supports_inline_contig_alloc() const;
174 HeapWord** top_addr() const;
175 HeapWord** end_addr() const;
176
177 // Perform a full collection of the heap; intended for use in implementing
178 // "System.gc". This implies as full a collection as the CollectedHeap
179 // supports. Caller does not hold the Heap_lock on entry.
180 void collect(GCCause::Cause cause);
181
182 // The same as above but assume that the caller holds the Heap_lock.
183 void collect_locked(GCCause::Cause cause);
184
185 // Perform a full collection of generations up to and including max_generation.
186 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
187 void collect(GCCause::Cause cause, Generation::Type max_generation);
188
189 // Returns "TRUE" iff "p" points into the committed areas of the heap.
190 // The methods is_in(), is_in_closed_subset() and is_in_youngest() may
191 // be expensive to compute in general, so, to prevent
192 // their inadvertent use in product jvm's, we restrict their use to
193 // assertion checking or verification only.
194 bool is_in(const void* p) const;
195
196 // override
197 bool is_in_closed_subset(const void* p) const {
198 if (UseConcMarkSweepGC) {
199 return is_in_reserved(p);
200 } else {
201 return is_in(p);
202 }
203 }
204
205 // Returns true if the reference is to an object in the reserved space
206 // for the young generation.
207 // Assumes the the young gen address range is less than that of the old gen.
297
298 // Total number of full collections completed.
299 unsigned int total_full_collections_completed() {
300 assert(_full_collections_completed <= _total_full_collections,
301 "Can't complete more collections than were started");
302 return _full_collections_completed;
303 }
304
305 // Update above counter, as appropriate, at the end of a stop-world GC cycle
306 unsigned int update_full_collections_completed();
307 // Update above counter, as appropriate, at the end of a concurrent GC cycle
308 unsigned int update_full_collections_completed(unsigned int count);
309
310 // Update "time of last gc" for all generations to "now".
311 void update_time_of_last_gc(jlong now) {
312 _young_gen->update_time_of_last_gc(now);
313 _old_gen->update_time_of_last_gc(now);
314 }
315
316 // Update the gc statistics for each generation.
317 void update_gc_stats(Generation* current_generation, bool full) {
318 _old_gen->update_gc_stats(current_generation, full);
319 }
320
321 bool no_gc_in_progress() { return !is_gc_active(); }
322
323 // Override.
324 void prepare_for_verify();
325
326 // Override.
327 void verify(bool silent, VerifyOption option);
328
329 // Override.
330 virtual void print_on(outputStream* st) const;
331 virtual void print_gc_threads_on(outputStream* st) const;
332 virtual void gc_threads_do(ThreadClosure* tc) const;
333 virtual void print_tracing_info() const;
334 virtual void print_on_error(outputStream* st) const;
335
336 // PrintGC, PrintGCDetails support
337 void print_heap_change(size_t prev_used) const;
338
346 };
347
348 // Apply "cl.do_generation" to all generations in the heap
349 // If "old_to_young" determines the order.
350 void generation_iterate(GenClosure* cl, bool old_to_young);
351
352 // Return "true" if all generations have reached the
353 // maximal committed limit that they can reach, without a garbage
354 // collection.
355 virtual bool is_maximal_no_gc() const;
356
357 // This function returns the "GenRemSet" object that allows us to scan
358 // generations in a fully generational heap.
359 GenRemSet* rem_set() { return _rem_set; }
360
361 // Convenience function to be used in situations where the heap type can be
362 // asserted to be this type.
363 static GenCollectedHeap* heap();
364
365 // Invoke the "do_oop" method of one of the closures "not_older_gens"
366 // or "older_gens" on root locations for the generations depending on
367 // the type. (The "older_gens" closure is used for scanning references
368 // from older generations; "not_older_gens" is used everywhere else.)
369 // If "younger_gens_as_roots" is false, younger generations are
370 // not scanned as roots; in this case, the caller must be arranging to
371 // scan the younger generations itself. (For example, a generation might
372 // explicitly mark reachable objects in younger generations, to avoid
373 // excess storage retention.)
374 // The "so" argument determines which of the roots
375 // the closure is applied to:
376 // "SO_None" does none;
377 enum ScanningOption {
378 SO_None = 0x0,
379 SO_AllCodeCache = 0x8,
380 SO_ScavengeCodeCache = 0x10
381 };
382
383 private:
384 void process_roots(StrongRootsScope* scope,
385 ScanningOption so,
386 OopClosure* strong_roots,
387 OopClosure* weak_roots,
388 CLDClosure* strong_cld_closure,
389 CLDClosure* weak_cld_closure,
390 CodeBlobClosure* code_roots);
391
392 public:
393 static const bool StrongAndWeakRoots = false;
394 static const bool StrongRootsOnly = true;
395
396 void gen_process_roots(StrongRootsScope* scope,
397 Generation::Type type,
398 bool younger_gens_as_roots,
399 ScanningOption so,
400 bool only_strong_roots,
401 OopsInGenClosure* not_older_gens,
402 OopsInGenClosure* older_gens,
403 CLDClosure* cld_closure);
404
405 // Apply "root_closure" to all the weak roots of the system.
406 // These include JNI weak roots, string table,
407 // and referents of reachable weak refs.
408 void gen_process_weak_roots(OopClosure* root_closure);
409
410 // Set the saved marks of generations, if that makes sense.
411 // In particular, if any generation might iterate over the oops
412 // in other generations, it should call this method.
413 void save_marks();
414
415 // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects
416 // allocated since the last call to save_marks in generations at or above
417 // "level". The "cur" closure is
418 // applied to references in the generation at "level", and the "older"
419 // closure to older generations.
420 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \
421 void oop_since_save_marks_iterate(Generation::Type start_gen, \
422 OopClosureType* cur, \
423 OopClosureType* older);
424
425 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL)
426
427 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL
428
429 // Returns "true" iff no allocations have occurred since the last
430 // call to "save_marks".
431 bool no_allocs_since_save_marks(bool include_young);
432
433 // Returns true if an incremental collection is likely to fail.
434 // We optionally consult the young gen, if asked to do so;
435 // otherwise we base our answer on whether the previous incremental
436 // collection attempt failed with no corrective action as of yet.
437 bool incremental_collection_will_fail(bool consult_young) {
438 // The first disjunct remembers if an incremental collection failed, even
439 // when we thought (second disjunct) that it would not.
440 return incremental_collection_failed() ||
441 (consult_young && !_young_gen->collection_attempt_is_safe());
442 }
443
444 // If a generation bails out of an incremental collection,
445 // it sets this flag.
446 bool incremental_collection_failed() const {
447 return _incremental_collection_failed;
448 }
449 void set_incremental_collection_failed() {
450 _incremental_collection_failed = true;
451 }
452 void clear_incremental_collection_failed() {
453 _incremental_collection_failed = false;
454 }
455
456 // Promotion of obj into gen failed. Try to promote obj to higher
457 // gens in ascending order; return the new location of obj if successful.
458 // Otherwise, try expand-and-allocate for obj in both the young and old
459 // generation; return the new location of obj if successful. Otherwise, return NULL.
460 oop handle_failed_promotion(Generation* old_gen,
461 oop obj,
462 size_t obj_size);
463
464 private:
465 // Accessor for memory state verification support
466 NOT_PRODUCT(
467 static size_t skip_header_HeapWords() { return _skip_header_HeapWords; }
468 )
469
470 // Override
471 void check_for_non_bad_heap_word_value(HeapWord* addr,
472 size_t size) PRODUCT_RETURN;
473
474 // For use by mark-sweep. As implemented, mark-sweep-compact is global
475 // in an essential way: compaction is performed across generations, by
476 // iterating over spaces.
477 void prepare_for_compaction();
478
479 // Perform a full collection of the generations up to and including max_generation.
480 // This is the low level interface used by the public versions of
481 // collect() and collect_locked(). Caller holds the Heap_lock on entry.
482 void collect_locked(GCCause::Cause cause, Generation::Type max_generation);
483
484 // Returns success or failure.
485 bool create_cms_collector();
486
487 // In support of ExplicitGCInvokesConcurrent functionality
488 bool should_do_concurrent_full_gc(GCCause::Cause cause);
489 void collect_mostly_concurrent(GCCause::Cause cause);
490
491 // Save the tops of the spaces in all generations
492 void record_gen_tops_before_GC() PRODUCT_RETURN;
493
494 protected:
495 void gc_prologue(bool full);
496 void gc_epilogue(bool full);
497 };
498
499 #endif // SHARE_VM_GC_SHARED_GENCOLLECTEDHEAP_HPP
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