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24
25 #ifndef SHARE_GC_SHARED_GENCOLLECTEDHEAP_HPP
26 #define SHARE_GC_SHARED_GENCOLLECTEDHEAP_HPP
27
28 #include "gc/shared/collectedHeap.hpp"
29 #include "gc/shared/generation.hpp"
30 #include "gc/shared/oopStorageParState.hpp"
31 #include "gc/shared/preGCValues.hpp"
32 #include "gc/shared/softRefGenPolicy.hpp"
33
34 class AdaptiveSizePolicy;
35 class CardTableRS;
36 class GCPolicyCounters;
37 class GenerationSpec;
38 class StrongRootsScope;
39 class SubTasksDone;
40 class WorkGang;
41
42 // A "GenCollectedHeap" is a CollectedHeap that uses generational
43 // collection. It has two generations, young and old.
44 class GenCollectedHeap : public CollectedHeap {
45 friend class Generation;
46 friend class DefNewGeneration;
47 friend class TenuredGeneration;
48 friend class ConcurrentMarkSweepGeneration;
49 friend class CMSCollector;
50 friend class GenMarkSweep;
51 friend class VM_GenCollectForAllocation;
52 friend class VM_GenCollectFull;
53 friend class VM_GenCollectFullConcurrent;
54 friend class VM_GC_HeapInspection;
55 friend class VM_HeapDumper;
56 friend class HeapInspection;
57 friend class GCCauseSetter;
58 friend class VMStructs;
59 public:
60 friend class VM_PopulateDumpSharedSpace;
61
62 enum GenerationType {
63 YoungGen,
64 OldGen
65 };
66
67 protected:
68 Generation* _young_gen;
69 Generation* _old_gen;
70
71 private:
72 GenerationSpec* _young_gen_spec;
73 GenerationSpec* _old_gen_spec;
74
75 // The singleton CardTable Remembered Set.
76 CardTableRS* _rem_set;
77
78 SoftRefGenPolicy _soft_ref_gen_policy;
79
80 // The sizing of the heap is controlled by a sizing policy.
81 AdaptiveSizePolicy* _size_policy;
82
83 GCPolicyCounters* _gc_policy_counters;
84
85 // Indicates that the most recent previous incremental collection failed.
86 // The flag is cleared when an action is taken that might clear the
87 // condition that caused that incremental collection to fail.
88 bool _incremental_collection_failed;
89
90 // In support of ExplicitGCInvokesConcurrent functionality
91 unsigned int _full_collections_completed;
92
93 // Collects the given generation.
94 void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab,
95 bool run_verification, bool clear_soft_refs,
96 bool restore_marks_for_biased_locking);
97
98 // Reserve aligned space for the heap as needed by the contained generations.
99 char* allocate(size_t alignment, ReservedSpace* heap_rs);
100
101 // Initialize ("weak") refs processing support
102 void ref_processing_init();
103
104 PreGenGCValues get_pre_gc_values() const;
105
106 protected:
107
108 // The set of potentially parallel tasks in root scanning.
109 enum GCH_strong_roots_tasks {
110 GCH_PS_Universe_oops_do,
111 GCH_PS_JNIHandles_oops_do,
112 GCH_PS_ObjectSynchronizer_oops_do,
113 GCH_PS_FlatProfiler_oops_do,
114 GCH_PS_Management_oops_do,
115 GCH_PS_SystemDictionary_oops_do,
116 GCH_PS_ClassLoaderDataGraph_oops_do,
117 GCH_PS_jvmti_oops_do,
118 GCH_PS_CodeCache_oops_do,
119 AOT_ONLY(GCH_PS_aot_oops_do COMMA)
120 GCH_PS_younger_gens,
121 // Leave this one last.
122 GCH_PS_NumElements
123 };
124
125 // Data structure for claiming the (potentially) parallel tasks in
126 // (gen-specific) roots processing.
127 SubTasksDone* _process_strong_tasks;
128
129 GCMemoryManager* _young_manager;
130 GCMemoryManager* _old_manager;
131
132 // Helper functions for allocation
133 HeapWord* attempt_allocation(size_t size,
134 bool is_tlab,
135 bool first_only);
136
137 // Helper function for two callbacks below.
138 // Considers collection of the first max_level+1 generations.
139 void do_collection(bool full,
140 bool clear_all_soft_refs,
141 size_t size,
142 bool is_tlab,
143 GenerationType max_generation);
144
145 // Callback from VM_GenCollectForAllocation operation.
146 // This function does everything necessary/possible to satisfy an
147 // allocation request that failed in the youngest generation that should
148 // have handled it (including collection, expansion, etc.)
149 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
150
151 // Callback from VM_GenCollectFull operation.
152 // Perform a full collection of the first max_level+1 generations.
153 virtual void do_full_collection(bool clear_all_soft_refs);
154 void do_full_collection(bool clear_all_soft_refs, GenerationType max_generation);
155
156 // Does the "cause" of GC indicate that
157 // we absolutely __must__ clear soft refs?
158 bool must_clear_all_soft_refs();
159
160 GenCollectedHeap(Generation::Name young,
161 Generation::Name old,
162 const char* policy_counters_name);
163
164 public:
165
166 // Returns JNI_OK on success
167 virtual jint initialize();
168 virtual CardTableRS* create_rem_set(const MemRegion& reserved_region);
169
170 void initialize_size_policy(size_t init_eden_size,
171 size_t init_promo_size,
172 size_t init_survivor_size);
173
174 // Does operations required after initialization has been done.
175 void post_initialize();
176
177 Generation* young_gen() const { return _young_gen; }
178 Generation* old_gen() const { return _old_gen; }
179
180 bool is_young_gen(const Generation* gen) const { return gen == _young_gen; }
181 bool is_old_gen(const Generation* gen) const { return gen == _old_gen; }
182
183 GenerationSpec* young_gen_spec() const;
184 GenerationSpec* old_gen_spec() const;
185
186 virtual SoftRefPolicy* soft_ref_policy() { return &_soft_ref_gen_policy; }
187
188 // Adaptive size policy
189 virtual AdaptiveSizePolicy* size_policy() {
190 return _size_policy;
191 }
192
193 // Performance Counter support
194 GCPolicyCounters* counters() { return _gc_policy_counters; }
195
196 size_t capacity() const;
197 size_t used() const;
198
199 // Save the "used_region" for both generations.
200 void save_used_regions();
201
202 size_t max_capacity() const;
203
204 HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);
205
206 // We may support a shared contiguous allocation area, if the youngest
207 // generation does.
208 bool supports_inline_contig_alloc() const;
209 HeapWord* volatile* top_addr() const;
210 HeapWord** end_addr() const;
211
212 // Perform a full collection of the heap; intended for use in implementing
213 // "System.gc". This implies as full a collection as the CollectedHeap
214 // supports. Caller does not hold the Heap_lock on entry.
215 virtual void collect(GCCause::Cause cause);
216
217 // The same as above but assume that the caller holds the Heap_lock.
218 void collect_locked(GCCause::Cause cause);
219
220 // Perform a full collection of generations up to and including max_generation.
221 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
222 void collect(GCCause::Cause cause, GenerationType max_generation);
223
224 // Returns "TRUE" iff "p" points into the committed areas of the heap.
225 // The methods is_in() and is_in_youngest() may be expensive to compute
226 // in general, so, to prevent their inadvertent use in product jvm's, we
227 // restrict their use to assertion checking or verification only.
228 bool is_in(const void* p) const;
229
230 // Returns true if the reference is to an object in the reserved space
231 // for the young generation.
232 // Assumes the the young gen address range is less than that of the old gen.
233 bool is_in_young(oop p);
234
235 #ifdef ASSERT
236 bool is_in_partial_collection(const void* p);
237 #endif
238
239 // Optimized nmethod scanning support routines
240 virtual void register_nmethod(nmethod* nm);
241 virtual void unregister_nmethod(nmethod* nm);
242 virtual void verify_nmethod(nmethod* nm);
243 virtual void flush_nmethod(nmethod* nm);
244
245 void prune_scavengable_nmethods();
246
247 // Iteration functions.
248 void oop_iterate(OopIterateClosure* cl);
249 void object_iterate(ObjectClosure* cl);
250 void safe_object_iterate(ObjectClosure* cl);
251 Space* space_containing(const void* addr) const;
252
253 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
254 // each address in the (reserved) heap is a member of exactly
255 // one block. The defining characteristic of a block is that it is
256 // possible to find its size, and thus to progress forward to the next
257 // block. (Blocks may be of different sizes.) Thus, blocks may
258 // represent Java objects, or they might be free blocks in a
259 // free-list-based heap (or subheap), as long as the two kinds are
260 // distinguishable and the size of each is determinable.
261
262 // Returns the address of the start of the "block" that contains the
263 // address "addr". We say "blocks" instead of "object" since some heaps
264 // may not pack objects densely; a chunk may either be an object or a
265 // non-object.
266 virtual HeapWord* block_start(const void* addr) const;
267
268 // Requires "addr" to be the start of a block, and returns "TRUE" iff
269 // the block is an object. Assumes (and verifies in non-product
270 // builds) that addr is in the allocated part of the heap and is
271 // the start of a chunk.
272 virtual bool block_is_obj(const HeapWord* addr) const;
273
274 // Section on TLAB's.
275 virtual bool supports_tlab_allocation() const;
276 virtual size_t tlab_capacity(Thread* thr) const;
277 virtual size_t tlab_used(Thread* thr) const;
278 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
279 virtual HeapWord* allocate_new_tlab(size_t min_size,
280 size_t requested_size,
281 size_t* actual_size);
282
283 // The "requestor" generation is performing some garbage collection
284 // action for which it would be useful to have scratch space. The
285 // requestor promises to allocate no more than "max_alloc_words" in any
286 // older generation (via promotion say.) Any blocks of space that can
287 // be provided are returned as a list of ScratchBlocks, sorted by
288 // decreasing size.
289 ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
290 // Allow each generation to reset any scratch space that it has
291 // contributed as it needs.
292 void release_scratch();
293
294 // Ensure parsability: override
295 virtual void ensure_parsability(bool retire_tlabs);
296
297 // Time in ms since the longest time a collector ran in
298 // in any generation.
299 virtual jlong millis_since_last_gc();
300
301 // Total number of full collections completed.
302 unsigned int total_full_collections_completed() {
303 assert(_full_collections_completed <= _total_full_collections,
304 "Can't complete more collections than were started");
305 return _full_collections_completed;
306 }
307
308 // Update above counter, as appropriate, at the end of a stop-world GC cycle
309 unsigned int update_full_collections_completed();
310 // Update above counter, as appropriate, at the end of a concurrent GC cycle
311 unsigned int update_full_collections_completed(unsigned int count);
312
313 // Update "time of last gc" for all generations to "now".
314 void update_time_of_last_gc(jlong now) {
315 _young_gen->update_time_of_last_gc(now);
316 _old_gen->update_time_of_last_gc(now);
317 }
318
319 // Update the gc statistics for each generation.
320 void update_gc_stats(Generation* current_generation, bool full) {
321 _old_gen->update_gc_stats(current_generation, full);
322 }
323
324 bool no_gc_in_progress() { return !is_gc_active(); }
325
326 // Override.
327 void prepare_for_verify();
328
329 // Override.
330 void verify(VerifyOption option);
331
332 // Override.
333 virtual void print_on(outputStream* st) const;
334 virtual void print_gc_threads_on(outputStream* st) const;
335 virtual void gc_threads_do(ThreadClosure* tc) const;
336 virtual void print_tracing_info() const;
337
338 void print_heap_change(const PreGenGCValues& pre_gc_values) const;
339
340 // The functions below are helper functions that a subclass of
341 // "CollectedHeap" can use in the implementation of its virtual
342 // functions.
343
344 class GenClosure : public StackObj {
345 public:
346 virtual void do_generation(Generation* gen) = 0;
347 };
348
349 // Apply "cl.do_generation" to all generations in the heap
350 // If "old_to_young" determines the order.
351 void generation_iterate(GenClosure* cl, bool old_to_young);
352
353 // Return "true" if all generations have reached the
354 // maximal committed limit that they can reach, without a garbage
355 // collection.
356 virtual bool is_maximal_no_gc() const;
357
358 // This function returns the CardTableRS object that allows us to scan
359 // generations in a fully generational heap.
360 CardTableRS* rem_set() { return _rem_set; }
361
362 // Convenience function to be used in situations where the heap type can be
363 // asserted to be this type.
364 static GenCollectedHeap* heap();
365
366 // The ScanningOption determines which of the roots
367 // the closure is applied to:
368 // "SO_None" does none;
369 enum ScanningOption {
370 SO_None = 0x0,
371 SO_AllCodeCache = 0x8,
372 SO_ScavengeCodeCache = 0x10
373 };
374
375 protected:
376 void process_roots(StrongRootsScope* scope,
377 ScanningOption so,
378 OopClosure* strong_roots,
379 CLDClosure* strong_cld_closure,
380 CLDClosure* weak_cld_closure,
381 CodeBlobToOopClosure* code_roots);
382
383 // Accessor for memory state verification support
384 NOT_PRODUCT(
385 virtual size_t skip_header_HeapWords() { return 0; }
386 )
387
388 virtual void gc_prologue(bool full);
389 virtual void gc_epilogue(bool full);
390
391 public:
392 void young_process_roots(StrongRootsScope* scope,
393 OopsInGenClosure* root_closure,
394 OopsInGenClosure* old_gen_closure,
395 CLDClosure* cld_closure);
396
397 void full_process_roots(StrongRootsScope* scope,
398 bool is_adjust_phase,
399 ScanningOption so,
400 bool only_strong_roots,
401 OopsInGenClosure* root_closure,
402 CLDClosure* cld_closure);
403
404 // Apply "root_closure" to all the weak roots of the system.
405 // These include JNI weak roots, string table,
406 // and referents of reachable weak refs.
407 void gen_process_weak_roots(OopClosure* root_closure);
408
409 // Set the saved marks of generations, if that makes sense.
410 // In particular, if any generation might iterate over the oops
411 // in other generations, it should call this method.
412 void save_marks();
413
414 // Returns "true" iff no allocations have occurred since the last
415 // call to "save_marks".
416 bool no_allocs_since_save_marks();
417
418 // Returns true if an incremental collection is likely to fail.
419 // We optionally consult the young gen, if asked to do so;
420 // otherwise we base our answer on whether the previous incremental
421 // collection attempt failed with no corrective action as of yet.
422 bool incremental_collection_will_fail(bool consult_young) {
423 // The first disjunct remembers if an incremental collection failed, even
424 // when we thought (second disjunct) that it would not.
425 return incremental_collection_failed() ||
426 (consult_young && !_young_gen->collection_attempt_is_safe());
427 }
428
429 // If a generation bails out of an incremental collection,
430 // it sets this flag.
431 bool incremental_collection_failed() const {
432 return _incremental_collection_failed;
433 }
434 void set_incremental_collection_failed() {
435 _incremental_collection_failed = true;
436 }
437 void clear_incremental_collection_failed() {
438 _incremental_collection_failed = false;
439 }
440
441 // Promotion of obj into gen failed. Try to promote obj to higher
442 // gens in ascending order; return the new location of obj if successful.
443 // Otherwise, try expand-and-allocate for obj in both the young and old
444 // generation; return the new location of obj if successful. Otherwise, return NULL.
445 oop handle_failed_promotion(Generation* old_gen,
446 oop obj,
447 size_t obj_size);
448
449
450 private:
451 // Return true if an allocation should be attempted in the older generation
452 // if it fails in the younger generation. Return false, otherwise.
453 bool should_try_older_generation_allocation(size_t word_size) const;
454
455 // Try to allocate space by expanding the heap.
456 HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
457
458 HeapWord* mem_allocate_work(size_t size,
459 bool is_tlab,
460 bool* gc_overhead_limit_was_exceeded);
461
462 // Override
463 void check_for_non_bad_heap_word_value(HeapWord* addr,
464 size_t size) PRODUCT_RETURN;
465
466 #if INCLUDE_SERIALGC
467 // For use by mark-sweep. As implemented, mark-sweep-compact is global
468 // in an essential way: compaction is performed across generations, by
469 // iterating over spaces.
470 void prepare_for_compaction();
471 #endif
472
473 // Perform a full collection of the generations up to and including max_generation.
474 // This is the low level interface used by the public versions of
475 // collect() and collect_locked(). Caller holds the Heap_lock on entry.
476 void collect_locked(GCCause::Cause cause, GenerationType max_generation);
477
478 // Save the tops of the spaces in all generations
479 void record_gen_tops_before_GC() PRODUCT_RETURN;
480
481 // Return true if we need to perform full collection.
482 bool should_do_full_collection(size_t size, bool full,
483 bool is_tlab, GenerationType max_gen) const;
484 };
485
486 #endif // SHARE_GC_SHARED_GENCOLLECTEDHEAP_HPP