1 /*
2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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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 class CollectorPolicy;
35
36 //
37 // CollectedHeap
38 // SharedHeap
39 // GenCollectedHeap
40 // G1CollectedHeap
41 // ParallelScavengeHeap
42 //
43 class CollectedHeap : public CHeapObj {
44 friend class VMStructs;
45 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
46 friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe
47
48 #ifdef ASSERT
49 static int _fire_out_of_memory_count;
50 #endif
51
52 // Used for filler objects (static, but initialized in ctor).
53 static size_t _filler_array_max_size;
54
55 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used
56 bool _defer_initial_card_mark;
57
58 protected:
59 MemRegion _reserved;
60 BarrierSet* _barrier_set;
61 bool _is_gc_active;
62 unsigned int _total_collections; // ... started
63 unsigned int _total_full_collections; // ... started
64 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
65 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
66
67 // Reason for current garbage collection. Should be set to
68 // a value reflecting no collection between collections.
69 GCCause::Cause _gc_cause;
70 GCCause::Cause _gc_lastcause;
71 PerfStringVariable* _perf_gc_cause;
72 PerfStringVariable* _perf_gc_lastcause;
73
74 // Constructor
75 CollectedHeap();
76
77 // Do common initializations that must follow instance construction,
78 // for example, those needing virtual calls.
79 // This code could perhaps be moved into initialize() but would
80 // be slightly more awkward because we want the latter to be a
81 // pure virtual.
82 void pre_initialize();
83
84 // Create a new tlab
85 virtual HeapWord* allocate_new_tlab(size_t size);
86
87 // Accumulate statistics on all tlabs.
88 virtual void accumulate_statistics_all_tlabs();
89
90 // Reinitialize tlabs before resuming mutators.
91 virtual void resize_all_tlabs();
92
93 protected:
94 // Allocate from the current thread's TLAB, with broken-out slow path.
95 inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);
96 static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);
97
98 // Allocate an uninitialized block of the given size, or returns NULL if
99 // this is impossible.
100 inline static HeapWord* common_mem_allocate_noinit(size_t size, bool is_noref, TRAPS);
101
102 // Like allocate_init, but the block returned by a successful allocation
103 // is guaranteed initialized to zeros.
104 inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS);
105
106 // Same as common_mem version, except memory is allocated in the permanent area
107 // If there is no permanent area, revert to common_mem_allocate_noinit
108 inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);
109
110 // Same as common_mem version, except memory is allocated in the permanent area
111 // If there is no permanent area, revert to common_mem_allocate_init
112 inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);
113
114 // Helper functions for (VM) allocation.
115 inline static void post_allocation_setup_common(KlassHandle klass,
116 HeapWord* obj, size_t size);
117 inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
118 HeapWord* objPtr,
119 size_t size);
120
121 inline static void post_allocation_setup_obj(KlassHandle klass,
122 HeapWord* obj, size_t size);
123
124 inline static void post_allocation_setup_array(KlassHandle klass,
125 HeapWord* obj, size_t size,
126 int length);
127
128 // Clears an allocated object.
129 inline static void init_obj(HeapWord* obj, size_t size);
130
131 // Filler object utilities.
132 static inline size_t filler_array_hdr_size();
133 static inline size_t filler_array_min_size();
134 static inline size_t filler_array_max_size();
135
136 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
137 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
138
139 // Fill with a single array; caller must ensure filler_array_min_size() <=
140 // words <= filler_array_max_size().
141 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
142
143 // Fill with a single object (either an int array or a java.lang.Object).
144 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
145
146 // Verification functions
147 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
148 PRODUCT_RETURN;
149 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
150 PRODUCT_RETURN;
151 debug_only(static void check_for_valid_allocation_state();)
152
153 public:
154 enum Name {
155 Abstract,
156 SharedHeap,
157 GenCollectedHeap,
158 ParallelScavengeHeap,
159 G1CollectedHeap
160 };
161
162 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
163
164 /**
165 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
166 * and JNI_OK on success.
167 */
168 virtual jint initialize() = 0;
169
170 // In many heaps, there will be a need to perform some initialization activities
171 // after the Universe is fully formed, but before general heap allocation is allowed.
172 // This is the correct place to place such initialization methods.
173 virtual void post_initialize() = 0;
174
175 MemRegion reserved_region() const { return _reserved; }
176 address base() const { return (address)reserved_region().start(); }
177
178 // Future cleanup here. The following functions should specify bytes or
179 // heapwords as part of their signature.
180 virtual size_t capacity() const = 0;
181 virtual size_t used() const = 0;
182
183 // Return "true" if the part of the heap that allocates Java
184 // objects has reached the maximal committed limit that it can
185 // reach, without a garbage collection.
186 virtual bool is_maximal_no_gc() const = 0;
187
188 virtual size_t permanent_capacity() const = 0;
189 virtual size_t permanent_used() const = 0;
190
191 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
192 // memory that the vm could make available for storing 'normal' java objects.
193 // This is based on the reserved address space, but should not include space
194 // that the vm uses internally for bookkeeping or temporary storage (e.g.,
195 // perm gen space or, in the case of the young gen, one of the survivor
196 // spaces).
197 virtual size_t max_capacity() const = 0;
198
199 // Returns "TRUE" if "p" points into the reserved area of the heap.
200 bool is_in_reserved(const void* p) const {
201 return _reserved.contains(p);
202 }
203
204 bool is_in_reserved_or_null(const void* p) const {
205 return p == NULL || is_in_reserved(p);
206 }
207
208 // Returns "TRUE" if "p" points to the head of an allocated object in the
209 // heap. Since this method can be expensive in general, we restrict its
210 // use to assertion checking only.
211 virtual bool is_in(const void* p) const = 0;
212
213 bool is_in_or_null(const void* p) const {
214 return p == NULL || is_in(p);
215 }
216
217 // Let's define some terms: a "closed" subset of a heap is one that
218 //
219 // 1) contains all currently-allocated objects, and
220 //
221 // 2) is closed under reference: no object in the closed subset
222 // references one outside the closed subset.
223 //
224 // Membership in a heap's closed subset is useful for assertions.
225 // Clearly, the entire heap is a closed subset, so the default
226 // implementation is to use "is_in_reserved". But this may not be too
227 // liberal to perform useful checking. Also, the "is_in" predicate
228 // defines a closed subset, but may be too expensive, since "is_in"
229 // verifies that its argument points to an object head. The
230 // "closed_subset" method allows a heap to define an intermediate
231 // predicate, allowing more precise checking than "is_in_reserved" at
232 // lower cost than "is_in."
233
234 // One important case is a heap composed of disjoint contiguous spaces,
235 // such as the Garbage-First collector. Such heaps have a convenient
236 // closed subset consisting of the allocated portions of those
237 // contiguous spaces.
238
239 // Return "TRUE" iff the given pointer points into the heap's defined
240 // closed subset (which defaults to the entire heap).
241 virtual bool is_in_closed_subset(const void* p) const {
242 return is_in_reserved(p);
243 }
244
245 bool is_in_closed_subset_or_null(const void* p) const {
246 return p == NULL || is_in_closed_subset(p);
247 }
248
249 // XXX is_permanent() and is_in_permanent() should be better named
250 // to distinguish one from the other.
251
252 // Returns "TRUE" if "p" is allocated as "permanent" data.
253 // If the heap does not use "permanent" data, returns the same
254 // value is_in_reserved() would return.
255 // NOTE: this actually returns true if "p" is in reserved space
256 // for the space not that it is actually allocated (i.e. in committed
257 // space). If you need the more conservative answer use is_permanent().
258 virtual bool is_in_permanent(const void *p) const = 0;
259
260 bool is_in_permanent_or_null(const void *p) const {
261 return p == NULL || is_in_permanent(p);
262 }
263
264 // Returns "TRUE" if "p" is in the committed area of "permanent" data.
265 // If the heap does not use "permanent" data, returns the same
266 // value is_in() would return.
267 virtual bool is_permanent(const void *p) const = 0;
268
269 bool is_permanent_or_null(const void *p) const {
270 return p == NULL || is_permanent(p);
271 }
272
273 // An object is scavengable if its location may move during a scavenge.
274 // (A scavenge is a GC which is not a full GC.)
275 // Currently, this just means it is not perm (and not null).
276 // This could change if we rethink what's in perm-gen.
277 bool is_scavengable(const void *p) const {
278 return !is_in_permanent_or_null(p);
279 }
280
281 // Returns "TRUE" if "p" is a method oop in the
282 // current heap, with high probability. This predicate
283 // is not stable, in general.
284 bool is_valid_method(oop p) const;
285
286 void set_gc_cause(GCCause::Cause v) {
287 if (UsePerfData) {
288 _gc_lastcause = _gc_cause;
289 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
290 _perf_gc_cause->set_value(GCCause::to_string(v));
291 }
292 _gc_cause = v;
293 }
294 GCCause::Cause gc_cause() { return _gc_cause; }
295
296 // Preload classes into the shared portion of the heap, and then dump
297 // that data to a file so that it can be loaded directly by another
298 // VM (then terminate).
299 virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }
300
301 // General obj/array allocation facilities.
302 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
303 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
304 inline static oop large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS);
305
306 // Special obj/array allocation facilities.
307 // Some heaps may want to manage "permanent" data uniquely. These default
308 // to the general routines if the heap does not support such handling.
309 inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);
310 // permanent_obj_allocate_no_klass_install() does not do the installation of
311 // the klass pointer in the newly created object (as permanent_obj_allocate()
312 // above does). This allows for a delay in the installation of the klass
313 // pointer that is needed during the create of klassKlass's. The
314 // method post_allocation_install_obj_klass() is used to install the
315 // klass pointer.
316 inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,
317 int size,
318 TRAPS);
319 inline static void post_allocation_install_obj_klass(KlassHandle klass,
320 oop obj,
321 int size);
322 inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);
323
324 // Raw memory allocation facilities
325 // The obj and array allocate methods are covers for these methods.
326 // The permanent allocation method should default to mem_allocate if
327 // permanent memory isn't supported.
328 virtual HeapWord* mem_allocate(size_t size,
329 bool is_noref,
330 bool is_tlab,
331 bool* gc_overhead_limit_was_exceeded) = 0;
332 virtual HeapWord* permanent_mem_allocate(size_t size) = 0;
333
334 // The boundary between a "large" and "small" array of primitives, in words.
335 virtual size_t large_typearray_limit() = 0;
336
337 // Utilities for turning raw memory into filler objects.
338 //
339 // min_fill_size() is the smallest region that can be filled.
340 // fill_with_objects() can fill arbitrary-sized regions of the heap using
341 // multiple objects. fill_with_object() is for regions known to be smaller
342 // than the largest array of integers; it uses a single object to fill the
343 // region and has slightly less overhead.
344 static size_t min_fill_size() {
345 return size_t(align_object_size(oopDesc::header_size()));
346 }
347
348 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
349
350 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
351 static void fill_with_object(MemRegion region, bool zap = true) {
352 fill_with_object(region.start(), region.word_size(), zap);
353 }
354 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
355 fill_with_object(start, pointer_delta(end, start), zap);
356 }
357
358 // Some heaps may offer a contiguous region for shared non-blocking
359 // allocation, via inlined code (by exporting the address of the top and
360 // end fields defining the extent of the contiguous allocation region.)
361
362 // This function returns "true" iff the heap supports this kind of
363 // allocation. (Default is "no".)
364 virtual bool supports_inline_contig_alloc() const {
365 return false;
366 }
367 // These functions return the addresses of the fields that define the
368 // boundaries of the contiguous allocation area. (These fields should be
369 // physically near to one another.)
370 virtual HeapWord** top_addr() const {
371 guarantee(false, "inline contiguous allocation not supported");
372 return NULL;
373 }
374 virtual HeapWord** end_addr() const {
375 guarantee(false, "inline contiguous allocation not supported");
376 return NULL;
377 }
378
379 // Some heaps may be in an unparseable state at certain times between
380 // collections. This may be necessary for efficient implementation of
381 // certain allocation-related activities. Calling this function before
382 // attempting to parse a heap ensures that the heap is in a parsable
383 // state (provided other concurrent activity does not introduce
384 // unparsability). It is normally expected, therefore, that this
385 // method is invoked with the world stopped.
386 // NOTE: if you override this method, make sure you call
387 // super::ensure_parsability so that the non-generational
388 // part of the work gets done. See implementation of
389 // CollectedHeap::ensure_parsability and, for instance,
390 // that of GenCollectedHeap::ensure_parsability().
391 // The argument "retire_tlabs" controls whether existing TLABs
392 // are merely filled or also retired, thus preventing further
393 // allocation from them and necessitating allocation of new TLABs.
394 virtual void ensure_parsability(bool retire_tlabs);
395
396 // Return an estimate of the maximum allocation that could be performed
397 // without triggering any collection or expansion activity. In a
398 // generational collector, for example, this is probably the largest
399 // allocation that could be supported (without expansion) in the youngest
400 // generation. It is "unsafe" because no locks are taken; the result
401 // should be treated as an approximation, not a guarantee, for use in
402 // heuristic resizing decisions.
403 virtual size_t unsafe_max_alloc() = 0;
404
405 // Section on thread-local allocation buffers (TLABs)
406 // If the heap supports thread-local allocation buffers, it should override
407 // the following methods:
408 // Returns "true" iff the heap supports thread-local allocation buffers.
409 // The default is "no".
410 virtual bool supports_tlab_allocation() const {
411 return false;
412 }
413 // The amount of space available for thread-local allocation buffers.
414 virtual size_t tlab_capacity(Thread *thr) const {
415 guarantee(false, "thread-local allocation buffers not supported");
416 return 0;
417 }
418 // An estimate of the maximum allocation that could be performed
419 // for thread-local allocation buffers without triggering any
420 // collection or expansion activity.
421 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
422 guarantee(false, "thread-local allocation buffers not supported");
423 return 0;
424 }
425
426 // Can a compiler initialize a new object without store barriers?
427 // This permission only extends from the creation of a new object
428 // via a TLAB up to the first subsequent safepoint. If such permission
429 // is granted for this heap type, the compiler promises to call
430 // defer_store_barrier() below on any slow path allocation of
431 // a new object for which such initializing store barriers will
432 // have been elided.
433 virtual bool can_elide_tlab_store_barriers() const = 0;
434
435 // If a compiler is eliding store barriers for TLAB-allocated objects,
436 // there is probably a corresponding slow path which can produce
437 // an object allocated anywhere. The compiler's runtime support
438 // promises to call this function on such a slow-path-allocated
439 // object before performing initializations that have elided
440 // store barriers. Returns new_obj, or maybe a safer copy thereof.
441 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
442
443 // Answers whether an initializing store to a new object currently
444 // allocated at the given address doesn't need a store
445 // barrier. Returns "true" if it doesn't need an initializing
446 // store barrier; answers "false" if it does.
447 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
448
449 // If a compiler is eliding store barriers for TLAB-allocated objects,
450 // we will be informed of a slow-path allocation by a call
451 // to new_store_pre_barrier() above. Such a call precedes the
452 // initialization of the object itself, and no post-store-barriers will
453 // be issued. Some heap types require that the barrier strictly follows
454 // the initializing stores. (This is currently implemented by deferring the
455 // barrier until the next slow-path allocation or gc-related safepoint.)
456 // This interface answers whether a particular heap type needs the card
457 // mark to be thus strictly sequenced after the stores.
458 virtual bool card_mark_must_follow_store() const = 0;
459
460 // If the CollectedHeap was asked to defer a store barrier above,
461 // this informs it to flush such a deferred store barrier to the
462 // remembered set.
463 virtual void flush_deferred_store_barrier(JavaThread* thread);
464
465 // Can a compiler elide a store barrier when it writes
466 // a permanent oop into the heap? Applies when the compiler
467 // is storing x to the heap, where x->is_perm() is true.
468 virtual bool can_elide_permanent_oop_store_barriers() const = 0;
469
470 // Does this heap support heap inspection (+PrintClassHistogram?)
471 virtual bool supports_heap_inspection() const = 0;
472
473 // Perform a collection of the heap; intended for use in implementing
474 // "System.gc". This probably implies as full a collection as the
475 // "CollectedHeap" supports.
476 virtual void collect(GCCause::Cause cause) = 0;
477
478 // This interface assumes that it's being called by the
479 // vm thread. It collects the heap assuming that the
480 // heap lock is already held and that we are executing in
481 // the context of the vm thread.
482 virtual void collect_as_vm_thread(GCCause::Cause cause) = 0;
483
484 // Returns the barrier set for this heap
485 BarrierSet* barrier_set() { return _barrier_set; }
486
487 // Returns "true" iff there is a stop-world GC in progress. (I assume
488 // that it should answer "false" for the concurrent part of a concurrent
489 // collector -- dld).
490 bool is_gc_active() const { return _is_gc_active; }
491
492 // Total number of GC collections (started)
493 unsigned int total_collections() const { return _total_collections; }
494 unsigned int total_full_collections() const { return _total_full_collections;}
495
496 // Increment total number of GC collections (started)
497 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
498 void increment_total_collections(bool full = false) {
499 _total_collections++;
500 if (full) {
501 increment_total_full_collections();
502 }
503 }
504
505 void increment_total_full_collections() { _total_full_collections++; }
506
507 // Return the AdaptiveSizePolicy for the heap.
508 virtual AdaptiveSizePolicy* size_policy() = 0;
509
510 // Return the CollectorPolicy for the heap
511 virtual CollectorPolicy* collector_policy() const = 0;
512
513 // Iterate over all the ref-containing fields of all objects, calling
514 // "cl.do_oop" on each. This includes objects in permanent memory.
515 virtual void oop_iterate(OopClosure* cl) = 0;
516
517 // Iterate over all objects, calling "cl.do_object" on each.
518 // This includes objects in permanent memory.
519 virtual void object_iterate(ObjectClosure* cl) = 0;
520
521 // Similar to object_iterate() except iterates only
522 // over live objects.
523 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
524
525 // Behaves the same as oop_iterate, except only traverses
526 // interior pointers contained in permanent memory. If there
527 // is no permanent memory, does nothing.
528 virtual void permanent_oop_iterate(OopClosure* cl) = 0;
529
530 // Behaves the same as object_iterate, except only traverses
531 // object contained in permanent memory. If there is no
532 // permanent memory, does nothing.
533 virtual void permanent_object_iterate(ObjectClosure* cl) = 0;
534
535 // NOTE! There is no requirement that a collector implement these
536 // functions.
537 //
538 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
539 // each address in the (reserved) heap is a member of exactly
540 // one block. The defining characteristic of a block is that it is
541 // possible to find its size, and thus to progress forward to the next
542 // block. (Blocks may be of different sizes.) Thus, blocks may
543 // represent Java objects, or they might be free blocks in a
544 // free-list-based heap (or subheap), as long as the two kinds are
545 // distinguishable and the size of each is determinable.
546
547 // Returns the address of the start of the "block" that contains the
548 // address "addr". We say "blocks" instead of "object" since some heaps
549 // may not pack objects densely; a chunk may either be an object or a
550 // non-object.
551 virtual HeapWord* block_start(const void* addr) const = 0;
552
553 // Requires "addr" to be the start of a chunk, and returns its size.
554 // "addr + size" is required to be the start of a new chunk, or the end
555 // of the active area of the heap.
556 virtual size_t block_size(const HeapWord* addr) const = 0;
557
558 // Requires "addr" to be the start of a block, and returns "TRUE" iff
559 // the block is an object.
560 virtual bool block_is_obj(const HeapWord* addr) const = 0;
561
562 // Returns the longest time (in ms) that has elapsed since the last
563 // time that any part of the heap was examined by a garbage collection.
564 virtual jlong millis_since_last_gc() = 0;
565
566 // Perform any cleanup actions necessary before allowing a verification.
567 virtual void prepare_for_verify() = 0;
568
569 // Generate any dumps preceding or following a full gc
570 void pre_full_gc_dump();
571 void post_full_gc_dump();
572
573 virtual void print() const = 0;
574 virtual void print_on(outputStream* st) const = 0;
575
576 // Print all GC threads (other than the VM thread)
577 // used by this heap.
578 virtual void print_gc_threads_on(outputStream* st) const = 0;
579 void print_gc_threads() { print_gc_threads_on(tty); }
580 // Iterator for all GC threads (other than VM thread)
581 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
582
583 // Print any relevant tracing info that flags imply.
584 // Default implementation does nothing.
585 virtual void print_tracing_info() const = 0;
586
587 // Heap verification
588 virtual void verify(bool allow_dirty, bool silent, bool option) = 0;
589
590 // Non product verification and debugging.
591 #ifndef PRODUCT
592 // Support for PromotionFailureALot. Return true if it's time to cause a
593 // promotion failure. The no-argument version uses
594 // this->_promotion_failure_alot_count as the counter.
595 inline bool promotion_should_fail(volatile size_t* count);
596 inline bool promotion_should_fail();
597
598 // Reset the PromotionFailureALot counters. Should be called at the end of a
599 // GC in which promotion failure ocurred.
600 inline void reset_promotion_should_fail(volatile size_t* count);
601 inline void reset_promotion_should_fail();
602 #endif // #ifndef PRODUCT
603
604 #ifdef ASSERT
605 static int fired_fake_oom() {
606 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
607 }
608 #endif
609 };
610
611 // Class to set and reset the GC cause for a CollectedHeap.
612
613 class GCCauseSetter : StackObj {
614 CollectedHeap* _heap;
615 GCCause::Cause _previous_cause;
616 public:
617 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
618 assert(SafepointSynchronize::is_at_safepoint(),
619 "This method manipulates heap state without locking");
620 _heap = heap;
621 _previous_cause = _heap->gc_cause();
622 _heap->set_gc_cause(cause);
623 }
624
625 ~GCCauseSetter() {
626 assert(SafepointSynchronize::is_at_safepoint(),
627 "This method manipulates heap state without locking");
628 _heap->set_gc_cause(_previous_cause);
629 }
630 };