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 SlidingForwarding;
39 class StrongRootsScope;
40 class SubTasksDone;
41 class WorkerThreads;
42
43 // A "GenCollectedHeap" is a CollectedHeap that uses generational
44 // collection. It has two generations, young and old.
45 class GenCollectedHeap : public CollectedHeap {
46 friend class Generation;
47 friend class DefNewGeneration;
48 friend class TenuredGeneration;
49 friend class GenMarkSweep;
50 friend class VM_GenCollectForAllocation;
51 friend class VM_GenCollectFull;
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 SlidingForwarding* _forwarding;
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
97 // Reserve aligned space for the heap as needed by the contained generations.
98 ReservedHeapSpace allocate(size_t alignment);
99
100 // Initialize ("weak") refs processing support
101 void ref_processing_init();
102
103 PreGenGCValues get_pre_gc_values() const;
104
105 protected:
106
107 GCMemoryManager* _young_manager;
108 GCMemoryManager* _old_manager;
109
110 // Helper functions for allocation
111 HeapWord* attempt_allocation(size_t size,
112 bool is_tlab,
113 bool first_only);
114
115 // Helper function for two callbacks below.
116 // Considers collection of the first max_level+1 generations.
117 void do_collection(bool full,
118 bool clear_all_soft_refs,
119 size_t size,
120 bool is_tlab,
121 GenerationType max_generation);
122
123 // Callback from VM_GenCollectForAllocation operation.
124 // This function does everything necessary/possible to satisfy an
125 // allocation request that failed in the youngest generation that should
126 // have handled it (including collection, expansion, etc.)
127 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
128
129 // Callback from VM_GenCollectFull operation.
130 // Perform a full collection of the first max_level+1 generations.
131 virtual void do_full_collection(bool clear_all_soft_refs);
132 void do_full_collection(bool clear_all_soft_refs, GenerationType max_generation);
133
134 // Does the "cause" of GC indicate that
135 // we absolutely __must__ clear soft refs?
136 bool must_clear_all_soft_refs();
137
138 GenCollectedHeap(Generation::Name young,
139 Generation::Name old,
140 const char* policy_counters_name);
141
142 public:
143
144 // Returns JNI_OK on success
145 virtual jint initialize();
146 virtual CardTableRS* create_rem_set(const MemRegion& reserved_region);
147
148 void initialize_size_policy(size_t init_eden_size,
149 size_t init_promo_size,
150 size_t init_survivor_size);
151
152 // Does operations required after initialization has been done.
153 void post_initialize();
154
155 Generation* young_gen() const { return _young_gen; }
156 Generation* old_gen() const { return _old_gen; }
157
158 bool is_young_gen(const Generation* gen) const { return gen == _young_gen; }
159 bool is_old_gen(const Generation* gen) const { return gen == _old_gen; }
160
161 MemRegion reserved_region() const { return _reserved; }
162 bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
163
164 GenerationSpec* young_gen_spec() const;
165 GenerationSpec* old_gen_spec() const;
166
167 virtual SoftRefPolicy* soft_ref_policy() { return &_soft_ref_gen_policy; }
168
169 // Adaptive size policy
170 virtual AdaptiveSizePolicy* size_policy() {
171 return _size_policy;
172 }
173
174 // Performance Counter support
175 GCPolicyCounters* counters() { return _gc_policy_counters; }
176
177 size_t capacity() const;
178 size_t used() const;
179
180 // Save the "used_region" for both generations.
181 void save_used_regions();
182
183 size_t max_capacity() const;
184
185 HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);
186
187 // Perform a full collection of the heap; intended for use in implementing
188 // "System.gc". This implies as full a collection as the CollectedHeap
189 // supports. Caller does not hold the Heap_lock on entry.
190 virtual void collect(GCCause::Cause cause);
191
192 // Perform a full collection of generations up to and including max_generation.
193 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
194 void collect(GCCause::Cause cause, GenerationType max_generation);
195
196 // Returns "TRUE" iff "p" points into the committed areas of the heap.
197 // The methods is_in() and is_in_youngest() may be expensive to compute
198 // in general, so, to prevent their inadvertent use in product jvm's, we
199 // restrict their use to assertion checking or verification only.
200 bool is_in(const void* p) const;
201
202 // Returns true if the reference is to an object in the reserved space
203 // for the young generation.
204 // Assumes the young gen address range is less than that of the old gen.
205 bool is_in_young(oop p) const;
206
207 virtual bool requires_barriers(stackChunkOop obj) const;
208
209 #ifdef ASSERT
210 bool is_in_partial_collection(const void* p);
211 #endif
212
213 // Optimized nmethod scanning support routines
214 virtual void register_nmethod(nmethod* nm);
215 virtual void unregister_nmethod(nmethod* nm);
216 virtual void verify_nmethod(nmethod* nm);
217 virtual void flush_nmethod(nmethod* nm);
218
219 void prune_scavengable_nmethods();
220
221 // Iteration functions.
222 void oop_iterate(OopIterateClosure* cl);
223 void object_iterate(ObjectClosure* cl);
224 Space* space_containing(const void* addr) const;
225
226 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
227 // each address in the (reserved) heap is a member of exactly
228 // one block. The defining characteristic of a block is that it is
229 // possible to find its size, and thus to progress forward to the next
230 // block. (Blocks may be of different sizes.) Thus, blocks may
231 // represent Java objects, or they might be free blocks in a
232 // free-list-based heap (or subheap), as long as the two kinds are
233 // distinguishable and the size of each is determinable.
234
235 // Returns the address of the start of the "block" that contains the
236 // address "addr". We say "blocks" instead of "object" since some heaps
237 // may not pack objects densely; a chunk may either be an object or a
238 // non-object.
239 HeapWord* block_start(const void* addr) const;
240
241 // Requires "addr" to be the start of a block, and returns "TRUE" iff
242 // the block is an object. Assumes (and verifies in non-product
243 // builds) that addr is in the allocated part of the heap and is
244 // the start of a chunk.
245 bool block_is_obj(const HeapWord* addr) const;
246
247 // Section on TLAB's.
248 virtual size_t tlab_capacity(Thread* thr) const;
249 virtual size_t tlab_used(Thread* thr) const;
250 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
251 virtual HeapWord* allocate_new_tlab(size_t min_size,
252 size_t requested_size,
253 size_t* actual_size);
254
255 // The "requestor" generation is performing some garbage collection
256 // action for which it would be useful to have scratch space. The
257 // requestor promises to allocate no more than "max_alloc_words" in any
258 // older generation (via promotion say.) Any blocks of space that can
259 // be provided are returned as a list of ScratchBlocks, sorted by
260 // decreasing size.
261 ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
262 // Allow each generation to reset any scratch space that it has
263 // contributed as it needs.
264 void release_scratch();
265
266 // Ensure parsability: override
267 virtual void ensure_parsability(bool retire_tlabs);
268
269 // Total number of full collections completed.
270 unsigned int total_full_collections_completed() {
271 assert(_full_collections_completed <= _total_full_collections,
272 "Can't complete more collections than were started");
273 return _full_collections_completed;
274 }
275
276 // Update above counter, as appropriate, at the end of a stop-world GC cycle
277 unsigned int update_full_collections_completed();
278
279 // Update the gc statistics for each generation.
280 void update_gc_stats(Generation* current_generation, bool full) {
281 _old_gen->update_gc_stats(current_generation, full);
282 }
283
284 bool no_gc_in_progress() { return !is_gc_active(); }
285
286 // Override.
287 void prepare_for_verify();
288
289 // Override.
290 void verify(VerifyOption option);
291
292 // Override.
293 virtual void print_on(outputStream* st) const;
294 virtual void gc_threads_do(ThreadClosure* tc) const;
295 virtual void print_tracing_info() const;
296
297 // Used to print information about locations in the hs_err file.
298 virtual bool print_location(outputStream* st, void* addr) const;
299
300 void print_heap_change(const PreGenGCValues& pre_gc_values) const;
301
302 // The functions below are helper functions that a subclass of
303 // "CollectedHeap" can use in the implementation of its virtual
304 // functions.
305
306 class GenClosure : public StackObj {
307 public:
308 virtual void do_generation(Generation* gen) = 0;
309 };
310
311 // Apply "cl.do_generation" to all generations in the heap
312 // If "old_to_young" determines the order.
313 void generation_iterate(GenClosure* cl, bool old_to_young);
314
315 // Return "true" if all generations have reached the
316 // maximal committed limit that they can reach, without a garbage
317 // collection.
318 virtual bool is_maximal_no_gc() const;
319
320 // This function returns the CardTableRS object that allows us to scan
321 // generations in a fully generational heap.
322 CardTableRS* rem_set() { return _rem_set; }
323
324 // Convenience function to be used in situations where the heap type can be
325 // asserted to be this type.
326 static GenCollectedHeap* heap();
327
328 SlidingForwarding* forwarding() const {
329 return _forwarding;
330 }
331
332 // The ScanningOption determines which of the roots
333 // the closure is applied to:
334 // "SO_None" does none;
335 enum ScanningOption {
336 SO_None = 0x0,
337 SO_AllCodeCache = 0x8,
338 SO_ScavengeCodeCache = 0x10
339 };
340
341 protected:
342 void process_roots(ScanningOption so,
343 OopClosure* strong_roots,
344 CLDClosure* strong_cld_closure,
345 CLDClosure* weak_cld_closure,
346 CodeBlobToOopClosure* code_roots);
347
348 virtual void gc_prologue(bool full);
349 virtual void gc_epilogue(bool full);
350
351 public:
352 void full_process_roots(bool is_adjust_phase,
353 ScanningOption so,
354 bool only_strong_roots,
355 OopClosure* root_closure,
356 CLDClosure* cld_closure);
357
358 // Apply "root_closure" to all the weak roots of the system.
359 // These include JNI weak roots, string table,
360 // and referents of reachable weak refs.
361 void gen_process_weak_roots(OopClosure* root_closure);
362
363 // Set the saved marks of generations, if that makes sense.
364 // In particular, if any generation might iterate over the oops
365 // in other generations, it should call this method.
366 void save_marks();
367
368 // Returns "true" iff no allocations have occurred since the last
369 // call to "save_marks".
370 bool no_allocs_since_save_marks();
371
372 // Returns true if an incremental collection is likely to fail.
373 // We optionally consult the young gen, if asked to do so;
374 // otherwise we base our answer on whether the previous incremental
375 // collection attempt failed with no corrective action as of yet.
376 bool incremental_collection_will_fail(bool consult_young) {
377 // The first disjunct remembers if an incremental collection failed, even
378 // when we thought (second disjunct) that it would not.
379 return incremental_collection_failed() ||
380 (consult_young && !_young_gen->collection_attempt_is_safe());
381 }
382
383 // If a generation bails out of an incremental collection,
384 // it sets this flag.
385 bool incremental_collection_failed() const {
386 return _incremental_collection_failed;
387 }
388 void set_incremental_collection_failed() {
389 _incremental_collection_failed = true;
390 }
391 void clear_incremental_collection_failed() {
392 _incremental_collection_failed = false;
393 }
394
395 // Promotion of obj into gen failed. Try to promote obj to higher
396 // gens in ascending order; return the new location of obj if successful.
397 // Otherwise, try expand-and-allocate for obj in both the young and old
398 // generation; return the new location of obj if successful. Otherwise, return NULL.
399 oop handle_failed_promotion(Generation* old_gen,
400 oop obj,
401 size_t obj_size);
402
403
404 private:
405 // Return true if an allocation should be attempted in the older generation
406 // if it fails in the younger generation. Return false, otherwise.
407 bool should_try_older_generation_allocation(size_t word_size) const;
408
409 // Try to allocate space by expanding the heap.
410 HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
411
412 HeapWord* mem_allocate_work(size_t size,
413 bool is_tlab,
414 bool* gc_overhead_limit_was_exceeded);
415
416 #if INCLUDE_SERIALGC
417 // For use by mark-sweep. As implemented, mark-sweep-compact is global
418 // in an essential way: compaction is performed across generations, by
419 // iterating over spaces.
420 void prepare_for_compaction();
421 #endif
422
423 // Save the tops of the spaces in all generations
424 void record_gen_tops_before_GC() PRODUCT_RETURN;
425
426 // Return true if we need to perform full collection.
427 bool should_do_full_collection(size_t size, bool full,
428 bool is_tlab, GenerationType max_gen) const;
429 };
430
431 #endif // SHARE_GC_SHARED_GENCOLLECTEDHEAP_HPP