Mercurial > hg > graal-compiler
annotate src/share/vm/gc_interface/collectedHeap.hpp @ 1027:39b01ab7035a
6888898: CMS: ReduceInitialCardMarks unsafe in the presence of cms precleaning
6889757: G1: enable card mark elision for initializing writes from compiled code (ReduceInitialCardMarks)
Summary: Defer the (compiler-elided) card-mark upon a slow-path allocation until after the store and before the next subsequent safepoint; G1 now answers yes to can_elide_tlab_write_barriers().
Reviewed-by: jcoomes, kvn, never
author | ysr |
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date | Fri, 16 Oct 2009 02:05:46 -0700 |
parents | 54b3b351d6f9 |
children | 2dd52dea6d28 |
rev | line source |
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0 | 1 /* |
579 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This | |
26 // is an abstract class: there may be many different kinds of heaps. This | |
27 // class defines the functions that a heap must implement, and contains | |
28 // infrastructure common to all heaps. | |
29 | |
30 class BarrierSet; | |
31 class ThreadClosure; | |
32 class AdaptiveSizePolicy; | |
33 class Thread; | |
34 | |
35 // | |
36 // CollectedHeap | |
37 // SharedHeap | |
38 // GenCollectedHeap | |
39 // G1CollectedHeap | |
40 // ParallelScavengeHeap | |
41 // | |
42 class CollectedHeap : public CHeapObj { | |
43 friend class VMStructs; | |
44 friend class IsGCActiveMark; // Block structured external access to _is_gc_active | |
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45 friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe |
0 | 46 |
47 #ifdef ASSERT | |
48 static int _fire_out_of_memory_count; | |
49 #endif | |
50 | |
481
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51 // Used for filler objects (static, but initialized in ctor). |
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52 static size_t _filler_array_max_size; |
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53 |
0 | 54 protected: |
55 MemRegion _reserved; | |
56 BarrierSet* _barrier_set; | |
57 bool _is_gc_active; | |
58 unsigned int _total_collections; // ... started | |
59 unsigned int _total_full_collections; // ... started | |
60 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) | |
61 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) | |
62 | |
63 // Reason for current garbage collection. Should be set to | |
64 // a value reflecting no collection between collections. | |
65 GCCause::Cause _gc_cause; | |
66 GCCause::Cause _gc_lastcause; | |
67 PerfStringVariable* _perf_gc_cause; | |
68 PerfStringVariable* _perf_gc_lastcause; | |
69 | |
70 // Constructor | |
71 CollectedHeap(); | |
72 | |
73 // Create a new tlab | |
74 virtual HeapWord* allocate_new_tlab(size_t size); | |
75 | |
76 // Fix up tlabs to make the heap well-formed again, | |
77 // optionally retiring the tlabs. | |
78 virtual void fill_all_tlabs(bool retire); | |
79 | |
80 // Accumulate statistics on all tlabs. | |
81 virtual void accumulate_statistics_all_tlabs(); | |
82 | |
83 // Reinitialize tlabs before resuming mutators. | |
84 virtual void resize_all_tlabs(); | |
85 | |
86 protected: | |
87 // Allocate from the current thread's TLAB, with broken-out slow path. | |
88 inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size); | |
89 static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size); | |
90 | |
91 // Allocate an uninitialized block of the given size, or returns NULL if | |
92 // this is impossible. | |
93 inline static HeapWord* common_mem_allocate_noinit(size_t size, bool is_noref, TRAPS); | |
94 | |
95 // Like allocate_init, but the block returned by a successful allocation | |
96 // is guaranteed initialized to zeros. | |
97 inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS); | |
98 | |
99 // Same as common_mem version, except memory is allocated in the permanent area | |
100 // If there is no permanent area, revert to common_mem_allocate_noinit | |
101 inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS); | |
102 | |
103 // Same as common_mem version, except memory is allocated in the permanent area | |
104 // If there is no permanent area, revert to common_mem_allocate_init | |
105 inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS); | |
106 | |
107 // Helper functions for (VM) allocation. | |
108 inline static void post_allocation_setup_common(KlassHandle klass, | |
109 HeapWord* obj, size_t size); | |
110 inline static void post_allocation_setup_no_klass_install(KlassHandle klass, | |
111 HeapWord* objPtr, | |
112 size_t size); | |
113 | |
114 inline static void post_allocation_setup_obj(KlassHandle klass, | |
115 HeapWord* obj, size_t size); | |
116 | |
117 inline static void post_allocation_setup_array(KlassHandle klass, | |
118 HeapWord* obj, size_t size, | |
119 int length); | |
120 | |
121 // Clears an allocated object. | |
122 inline static void init_obj(HeapWord* obj, size_t size); | |
123 | |
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124 // Filler object utilities. |
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125 static inline size_t filler_array_hdr_size(); |
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126 static inline size_t filler_array_min_size(); |
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127 static inline size_t filler_array_max_size(); |
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128 |
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129 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) |
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130 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words);) |
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131 |
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132 // Fill with a single array; caller must ensure filler_array_min_size() <= |
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133 // words <= filler_array_max_size(). |
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134 static inline void fill_with_array(HeapWord* start, size_t words); |
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135 |
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136 // Fill with a single object (either an int array or a java.lang.Object). |
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137 static inline void fill_with_object_impl(HeapWord* start, size_t words); |
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138 |
0 | 139 // Verification functions |
140 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) | |
141 PRODUCT_RETURN; | |
142 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) | |
143 PRODUCT_RETURN; | |
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144 debug_only(static void check_for_valid_allocation_state();) |
0 | 145 |
146 public: | |
147 enum Name { | |
148 Abstract, | |
149 SharedHeap, | |
150 GenCollectedHeap, | |
151 ParallelScavengeHeap, | |
152 G1CollectedHeap | |
153 }; | |
154 | |
155 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; } | |
156 | |
157 /** | |
158 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, | |
159 * and JNI_OK on success. | |
160 */ | |
161 virtual jint initialize() = 0; | |
162 | |
163 // In many heaps, there will be a need to perform some initialization activities | |
164 // after the Universe is fully formed, but before general heap allocation is allowed. | |
165 // This is the correct place to place such initialization methods. | |
166 virtual void post_initialize() = 0; | |
167 | |
168 MemRegion reserved_region() const { return _reserved; } | |
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169 address base() const { return (address)reserved_region().start(); } |
0 | 170 |
171 // Future cleanup here. The following functions should specify bytes or | |
172 // heapwords as part of their signature. | |
173 virtual size_t capacity() const = 0; | |
174 virtual size_t used() const = 0; | |
175 | |
176 // Return "true" if the part of the heap that allocates Java | |
177 // objects has reached the maximal committed limit that it can | |
178 // reach, without a garbage collection. | |
179 virtual bool is_maximal_no_gc() const = 0; | |
180 | |
181 virtual size_t permanent_capacity() const = 0; | |
182 virtual size_t permanent_used() const = 0; | |
183 | |
184 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of | |
185 // memory that the vm could make available for storing 'normal' java objects. | |
186 // This is based on the reserved address space, but should not include space | |
187 // that the vm uses internally for bookkeeping or temporary storage (e.g., | |
188 // perm gen space or, in the case of the young gen, one of the survivor | |
189 // spaces). | |
190 virtual size_t max_capacity() const = 0; | |
191 | |
192 // Returns "TRUE" if "p" points into the reserved area of the heap. | |
193 bool is_in_reserved(const void* p) const { | |
194 return _reserved.contains(p); | |
195 } | |
196 | |
197 bool is_in_reserved_or_null(const void* p) const { | |
198 return p == NULL || is_in_reserved(p); | |
199 } | |
200 | |
201 // Returns "TRUE" if "p" points to the head of an allocated object in the | |
202 // heap. Since this method can be expensive in general, we restrict its | |
203 // use to assertion checking only. | |
204 virtual bool is_in(const void* p) const = 0; | |
205 | |
206 bool is_in_or_null(const void* p) const { | |
207 return p == NULL || is_in(p); | |
208 } | |
209 | |
210 // Let's define some terms: a "closed" subset of a heap is one that | |
211 // | |
212 // 1) contains all currently-allocated objects, and | |
213 // | |
214 // 2) is closed under reference: no object in the closed subset | |
215 // references one outside the closed subset. | |
216 // | |
217 // Membership in a heap's closed subset is useful for assertions. | |
218 // Clearly, the entire heap is a closed subset, so the default | |
219 // implementation is to use "is_in_reserved". But this may not be too | |
220 // liberal to perform useful checking. Also, the "is_in" predicate | |
221 // defines a closed subset, but may be too expensive, since "is_in" | |
222 // verifies that its argument points to an object head. The | |
223 // "closed_subset" method allows a heap to define an intermediate | |
224 // predicate, allowing more precise checking than "is_in_reserved" at | |
225 // lower cost than "is_in." | |
226 | |
227 // One important case is a heap composed of disjoint contiguous spaces, | |
228 // such as the Garbage-First collector. Such heaps have a convenient | |
229 // closed subset consisting of the allocated portions of those | |
230 // contiguous spaces. | |
231 | |
232 // Return "TRUE" iff the given pointer points into the heap's defined | |
233 // closed subset (which defaults to the entire heap). | |
234 virtual bool is_in_closed_subset(const void* p) const { | |
235 return is_in_reserved(p); | |
236 } | |
237 | |
238 bool is_in_closed_subset_or_null(const void* p) const { | |
239 return p == NULL || is_in_closed_subset(p); | |
240 } | |
241 | |
941 | 242 // XXX is_permanent() and is_in_permanent() should be better named |
243 // to distinguish one from the other. | |
244 | |
0 | 245 // Returns "TRUE" if "p" is allocated as "permanent" data. |
246 // If the heap does not use "permanent" data, returns the same | |
247 // value is_in_reserved() would return. | |
248 // NOTE: this actually returns true if "p" is in reserved space | |
249 // for the space not that it is actually allocated (i.e. in committed | |
250 // space). If you need the more conservative answer use is_permanent(). | |
251 virtual bool is_in_permanent(const void *p) const = 0; | |
252 | |
941 | 253 bool is_in_permanent_or_null(const void *p) const { |
254 return p == NULL || is_in_permanent(p); | |
255 } | |
256 | |
0 | 257 // Returns "TRUE" if "p" is in the committed area of "permanent" data. |
258 // If the heap does not use "permanent" data, returns the same | |
259 // value is_in() would return. | |
260 virtual bool is_permanent(const void *p) const = 0; | |
261 | |
941 | 262 bool is_permanent_or_null(const void *p) const { |
263 return p == NULL || is_permanent(p); | |
0 | 264 } |
265 | |
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266 // An object is scavengable if its location may move during a scavenge. |
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267 // (A scavenge is a GC which is not a full GC.) |
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268 // Currently, this just means it is not perm (and not null). |
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269 // This could change if we rethink what's in perm-gen. |
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270 bool is_scavengable(const void *p) const { |
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271 return !is_in_permanent_or_null(p); |
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272 } |
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273 |
0 | 274 // Returns "TRUE" if "p" is a method oop in the |
275 // current heap, with high probability. This predicate | |
276 // is not stable, in general. | |
277 bool is_valid_method(oop p) const; | |
278 | |
279 void set_gc_cause(GCCause::Cause v) { | |
280 if (UsePerfData) { | |
281 _gc_lastcause = _gc_cause; | |
282 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); | |
283 _perf_gc_cause->set_value(GCCause::to_string(v)); | |
284 } | |
285 _gc_cause = v; | |
286 } | |
287 GCCause::Cause gc_cause() { return _gc_cause; } | |
288 | |
289 // Preload classes into the shared portion of the heap, and then dump | |
290 // that data to a file so that it can be loaded directly by another | |
291 // VM (then terminate). | |
292 virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); } | |
293 | |
294 // General obj/array allocation facilities. | |
295 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS); | |
296 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS); | |
297 inline static oop large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS); | |
298 | |
299 // Special obj/array allocation facilities. | |
300 // Some heaps may want to manage "permanent" data uniquely. These default | |
301 // to the general routines if the heap does not support such handling. | |
302 inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS); | |
303 // permanent_obj_allocate_no_klass_install() does not do the installation of | |
304 // the klass pointer in the newly created object (as permanent_obj_allocate() | |
305 // above does). This allows for a delay in the installation of the klass | |
306 // pointer that is needed during the create of klassKlass's. The | |
307 // method post_allocation_install_obj_klass() is used to install the | |
308 // klass pointer. | |
309 inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass, | |
310 int size, | |
311 TRAPS); | |
312 inline static void post_allocation_install_obj_klass(KlassHandle klass, | |
313 oop obj, | |
314 int size); | |
315 inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS); | |
316 | |
317 // Raw memory allocation facilities | |
318 // The obj and array allocate methods are covers for these methods. | |
319 // The permanent allocation method should default to mem_allocate if | |
320 // permanent memory isn't supported. | |
321 virtual HeapWord* mem_allocate(size_t size, | |
322 bool is_noref, | |
323 bool is_tlab, | |
324 bool* gc_overhead_limit_was_exceeded) = 0; | |
325 virtual HeapWord* permanent_mem_allocate(size_t size) = 0; | |
326 | |
327 // The boundary between a "large" and "small" array of primitives, in words. | |
328 virtual size_t large_typearray_limit() = 0; | |
329 | |
481
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330 // Utilities for turning raw memory into filler objects. |
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331 // |
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332 // min_fill_size() is the smallest region that can be filled. |
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333 // fill_with_objects() can fill arbitrary-sized regions of the heap using |
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334 // multiple objects. fill_with_object() is for regions known to be smaller |
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335 // than the largest array of integers; it uses a single object to fill the |
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336 // region and has slightly less overhead. |
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337 static size_t min_fill_size() { |
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338 return size_t(align_object_size(oopDesc::header_size())); |
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339 } |
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340 |
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341 static void fill_with_objects(HeapWord* start, size_t words); |
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342 |
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343 static void fill_with_object(HeapWord* start, size_t words); |
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344 static void fill_with_object(MemRegion region) { |
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345 fill_with_object(region.start(), region.word_size()); |
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346 } |
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347 static void fill_with_object(HeapWord* start, HeapWord* end) { |
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348 fill_with_object(start, pointer_delta(end, start)); |
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349 } |
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350 |
0 | 351 // Some heaps may offer a contiguous region for shared non-blocking |
352 // allocation, via inlined code (by exporting the address of the top and | |
353 // end fields defining the extent of the contiguous allocation region.) | |
354 | |
355 // This function returns "true" iff the heap supports this kind of | |
356 // allocation. (Default is "no".) | |
357 virtual bool supports_inline_contig_alloc() const { | |
358 return false; | |
359 } | |
360 // These functions return the addresses of the fields that define the | |
361 // boundaries of the contiguous allocation area. (These fields should be | |
362 // physically near to one another.) | |
363 virtual HeapWord** top_addr() const { | |
364 guarantee(false, "inline contiguous allocation not supported"); | |
365 return NULL; | |
366 } | |
367 virtual HeapWord** end_addr() const { | |
368 guarantee(false, "inline contiguous allocation not supported"); | |
369 return NULL; | |
370 } | |
371 | |
372 // Some heaps may be in an unparseable state at certain times between | |
373 // collections. This may be necessary for efficient implementation of | |
374 // certain allocation-related activities. Calling this function before | |
375 // attempting to parse a heap ensures that the heap is in a parsable | |
376 // state (provided other concurrent activity does not introduce | |
377 // unparsability). It is normally expected, therefore, that this | |
378 // method is invoked with the world stopped. | |
379 // NOTE: if you override this method, make sure you call | |
380 // super::ensure_parsability so that the non-generational | |
381 // part of the work gets done. See implementation of | |
382 // CollectedHeap::ensure_parsability and, for instance, | |
383 // that of GenCollectedHeap::ensure_parsability(). | |
384 // The argument "retire_tlabs" controls whether existing TLABs | |
385 // are merely filled or also retired, thus preventing further | |
386 // allocation from them and necessitating allocation of new TLABs. | |
387 virtual void ensure_parsability(bool retire_tlabs); | |
388 | |
389 // Return an estimate of the maximum allocation that could be performed | |
390 // without triggering any collection or expansion activity. In a | |
391 // generational collector, for example, this is probably the largest | |
392 // allocation that could be supported (without expansion) in the youngest | |
393 // generation. It is "unsafe" because no locks are taken; the result | |
394 // should be treated as an approximation, not a guarantee, for use in | |
395 // heuristic resizing decisions. | |
396 virtual size_t unsafe_max_alloc() = 0; | |
397 | |
398 // Section on thread-local allocation buffers (TLABs) | |
399 // If the heap supports thread-local allocation buffers, it should override | |
400 // the following methods: | |
401 // Returns "true" iff the heap supports thread-local allocation buffers. | |
402 // The default is "no". | |
403 virtual bool supports_tlab_allocation() const { | |
404 return false; | |
405 } | |
406 // The amount of space available for thread-local allocation buffers. | |
407 virtual size_t tlab_capacity(Thread *thr) const { | |
408 guarantee(false, "thread-local allocation buffers not supported"); | |
409 return 0; | |
410 } | |
411 // An estimate of the maximum allocation that could be performed | |
412 // for thread-local allocation buffers without triggering any | |
413 // collection or expansion activity. | |
414 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { | |
415 guarantee(false, "thread-local allocation buffers not supported"); | |
416 return 0; | |
417 } | |
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418 |
0 | 419 // Can a compiler initialize a new object without store barriers? |
420 // This permission only extends from the creation of a new object | |
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421 // via a TLAB up to the first subsequent safepoint. If such permission |
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422 // is granted for this heap type, the compiler promises to call |
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423 // defer_store_barrier() below on any slow path allocation of |
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424 // a new object for which such initializing store barriers will |
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425 // have been elided. |
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426 virtual bool can_elide_tlab_store_barriers() const = 0; |
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427 |
0 | 428 // If a compiler is eliding store barriers for TLAB-allocated objects, |
429 // there is probably a corresponding slow path which can produce | |
430 // an object allocated anywhere. The compiler's runtime support | |
431 // promises to call this function on such a slow-path-allocated | |
432 // object before performing initializations that have elided | |
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433 // store barriers. Returns new_obj, or maybe a safer copy thereof. |
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434 virtual oop defer_store_barrier(JavaThread* thread, oop new_obj); |
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435 |
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436 // Answers whether an initializing store to a new object currently |
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437 // allocated at the given address doesn't need a (deferred) store |
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438 // barrier. Returns "true" if it doesn't need an initializing |
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439 // store barrier; answers "false" if it does. |
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440 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0; |
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441 |
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442 // If the CollectedHeap was asked to defer a store barrier above, |
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443 // this informs it to flush such a deferred store barrier to the |
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444 // remembered set. |
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445 virtual void flush_deferred_store_barrier(JavaThread* thread); |
0 | 446 |
447 // Can a compiler elide a store barrier when it writes | |
448 // a permanent oop into the heap? Applies when the compiler | |
449 // is storing x to the heap, where x->is_perm() is true. | |
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450 virtual bool can_elide_permanent_oop_store_barriers() const = 0; |
0 | 451 |
452 // Does this heap support heap inspection (+PrintClassHistogram?) | |
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453 virtual bool supports_heap_inspection() const = 0; |
0 | 454 |
455 // Perform a collection of the heap; intended for use in implementing | |
456 // "System.gc". This probably implies as full a collection as the | |
457 // "CollectedHeap" supports. | |
458 virtual void collect(GCCause::Cause cause) = 0; | |
459 | |
460 // This interface assumes that it's being called by the | |
461 // vm thread. It collects the heap assuming that the | |
462 // heap lock is already held and that we are executing in | |
463 // the context of the vm thread. | |
464 virtual void collect_as_vm_thread(GCCause::Cause cause) = 0; | |
465 | |
466 // Returns the barrier set for this heap | |
467 BarrierSet* barrier_set() { return _barrier_set; } | |
468 | |
469 // Returns "true" iff there is a stop-world GC in progress. (I assume | |
470 // that it should answer "false" for the concurrent part of a concurrent | |
471 // collector -- dld). | |
472 bool is_gc_active() const { return _is_gc_active; } | |
473 | |
474 // Total number of GC collections (started) | |
475 unsigned int total_collections() const { return _total_collections; } | |
476 unsigned int total_full_collections() const { return _total_full_collections;} | |
477 | |
478 // Increment total number of GC collections (started) | |
479 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 | |
480 void increment_total_collections(bool full = false) { | |
481 _total_collections++; | |
482 if (full) { | |
483 increment_total_full_collections(); | |
484 } | |
485 } | |
486 | |
487 void increment_total_full_collections() { _total_full_collections++; } | |
488 | |
489 // Return the AdaptiveSizePolicy for the heap. | |
490 virtual AdaptiveSizePolicy* size_policy() = 0; | |
491 | |
492 // Iterate over all the ref-containing fields of all objects, calling | |
493 // "cl.do_oop" on each. This includes objects in permanent memory. | |
494 virtual void oop_iterate(OopClosure* cl) = 0; | |
495 | |
496 // Iterate over all objects, calling "cl.do_object" on each. | |
497 // This includes objects in permanent memory. | |
498 virtual void object_iterate(ObjectClosure* cl) = 0; | |
499 | |
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500 // Similar to object_iterate() except iterates only |
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501 // over live objects. |
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502 virtual void safe_object_iterate(ObjectClosure* cl) = 0; |
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503 |
0 | 504 // Behaves the same as oop_iterate, except only traverses |
505 // interior pointers contained in permanent memory. If there | |
506 // is no permanent memory, does nothing. | |
507 virtual void permanent_oop_iterate(OopClosure* cl) = 0; | |
508 | |
509 // Behaves the same as object_iterate, except only traverses | |
510 // object contained in permanent memory. If there is no | |
511 // permanent memory, does nothing. | |
512 virtual void permanent_object_iterate(ObjectClosure* cl) = 0; | |
513 | |
514 // NOTE! There is no requirement that a collector implement these | |
515 // functions. | |
516 // | |
517 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, | |
518 // each address in the (reserved) heap is a member of exactly | |
519 // one block. The defining characteristic of a block is that it is | |
520 // possible to find its size, and thus to progress forward to the next | |
521 // block. (Blocks may be of different sizes.) Thus, blocks may | |
522 // represent Java objects, or they might be free blocks in a | |
523 // free-list-based heap (or subheap), as long as the two kinds are | |
524 // distinguishable and the size of each is determinable. | |
525 | |
526 // Returns the address of the start of the "block" that contains the | |
527 // address "addr". We say "blocks" instead of "object" since some heaps | |
528 // may not pack objects densely; a chunk may either be an object or a | |
529 // non-object. | |
530 virtual HeapWord* block_start(const void* addr) const = 0; | |
531 | |
532 // Requires "addr" to be the start of a chunk, and returns its size. | |
533 // "addr + size" is required to be the start of a new chunk, or the end | |
534 // of the active area of the heap. | |
535 virtual size_t block_size(const HeapWord* addr) const = 0; | |
536 | |
537 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
538 // the block is an object. | |
539 virtual bool block_is_obj(const HeapWord* addr) const = 0; | |
540 | |
541 // Returns the longest time (in ms) that has elapsed since the last | |
542 // time that any part of the heap was examined by a garbage collection. | |
543 virtual jlong millis_since_last_gc() = 0; | |
544 | |
545 // Perform any cleanup actions necessary before allowing a verification. | |
546 virtual void prepare_for_verify() = 0; | |
547 | |
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548 // Generate any dumps preceding or following a full gc |
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549 void pre_full_gc_dump(); |
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550 void post_full_gc_dump(); |
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551 |
0 | 552 virtual void print() const = 0; |
553 virtual void print_on(outputStream* st) const = 0; | |
554 | |
555 // Print all GC threads (other than the VM thread) | |
556 // used by this heap. | |
557 virtual void print_gc_threads_on(outputStream* st) const = 0; | |
558 void print_gc_threads() { print_gc_threads_on(tty); } | |
559 // Iterator for all GC threads (other than VM thread) | |
560 virtual void gc_threads_do(ThreadClosure* tc) const = 0; | |
561 | |
562 // Print any relevant tracing info that flags imply. | |
563 // Default implementation does nothing. | |
564 virtual void print_tracing_info() const = 0; | |
565 | |
566 // Heap verification | |
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567 virtual void verify(bool allow_dirty, bool silent, bool option) = 0; |
0 | 568 |
569 // Non product verification and debugging. | |
570 #ifndef PRODUCT | |
571 // Support for PromotionFailureALot. Return true if it's time to cause a | |
572 // promotion failure. The no-argument version uses | |
573 // this->_promotion_failure_alot_count as the counter. | |
574 inline bool promotion_should_fail(volatile size_t* count); | |
575 inline bool promotion_should_fail(); | |
576 | |
577 // Reset the PromotionFailureALot counters. Should be called at the end of a | |
578 // GC in which promotion failure ocurred. | |
579 inline void reset_promotion_should_fail(volatile size_t* count); | |
580 inline void reset_promotion_should_fail(); | |
581 #endif // #ifndef PRODUCT | |
582 | |
583 #ifdef ASSERT | |
584 static int fired_fake_oom() { | |
585 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); | |
586 } | |
587 #endif | |
588 }; | |
589 | |
590 // Class to set and reset the GC cause for a CollectedHeap. | |
591 | |
592 class GCCauseSetter : StackObj { | |
593 CollectedHeap* _heap; | |
594 GCCause::Cause _previous_cause; | |
595 public: | |
596 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { | |
597 assert(SafepointSynchronize::is_at_safepoint(), | |
598 "This method manipulates heap state without locking"); | |
599 _heap = heap; | |
600 _previous_cause = _heap->gc_cause(); | |
601 _heap->set_gc_cause(cause); | |
602 } | |
603 | |
604 ~GCCauseSetter() { | |
605 assert(SafepointSynchronize::is_at_safepoint(), | |
606 "This method manipulates heap state without locking"); | |
607 _heap->set_gc_cause(_previous_cause); | |
608 } | |
609 }; |