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