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