1 /*
2 * Copyright (c) 2001, 2018, 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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20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP
27
28 #include "gc/shared/gcCause.hpp"
29 #include "gc/shared/gcWhen.hpp"
30 #include "memory/allocation.hpp"
31 #include "runtime/handles.hpp"
32 #include "runtime/perfData.hpp"
33 #include "runtime/safepoint.hpp"
34 #include "utilities/debug.hpp"
35 #include "utilities/events.hpp"
36 #include "utilities/formatBuffer.hpp"
37 #include "utilities/growableArray.hpp"
38
39 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
40 // is an abstract class: there may be many different kinds of heaps. This
41 // class defines the functions that a heap must implement, and contains
42 // infrastructure common to all heaps.
43
44 class AdaptiveSizePolicy;
45 class BarrierSet;
46 class CollectorPolicy;
47 class GCHeapSummary;
48 class GCTimer;
49 class GCTracer;
50 class GCMemoryManager;
51 class MemoryPool;
52 class MetaspaceSummary;
53 class SoftRefPolicy;
54 class Thread;
55 class ThreadClosure;
56 class VirtualSpaceSummary;
57 class WorkGang;
58 class nmethod;
59
60 class GCMessage : public FormatBuffer<1024> {
61 public:
62 bool is_before;
63
64 public:
65 GCMessage() {}
66 };
67
68 class CollectedHeap;
69
70 class GCHeapLog : public EventLogBase<GCMessage> {
71 private:
72 void log_heap(CollectedHeap* heap, bool before);
73
74 public:
75 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
76
77 void log_heap_before(CollectedHeap* heap) {
78 log_heap(heap, true);
79 }
80 void log_heap_after(CollectedHeap* heap) {
81 log_heap(heap, false);
82 }
83 };
84
85 //
86 // CollectedHeap
87 // GenCollectedHeap
88 // SerialHeap
89 // CMSHeap
90 // G1CollectedHeap
91 // ParallelScavengeHeap
92 //
93 class CollectedHeap : public CHeapObj<mtInternal> {
94 friend class VMStructs;
95 friend class JVMCIVMStructs;
96 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
97
98 private:
99 #ifdef ASSERT
100 static int _fire_out_of_memory_count;
101 #endif
102
103 GCHeapLog* _gc_heap_log;
104
105 MemRegion _reserved;
106
107 protected:
108 bool _is_gc_active;
109
110 // Used for filler objects (static, but initialized in ctor).
111 static size_t _filler_array_max_size;
112
113 unsigned int _total_collections; // ... started
114 unsigned int _total_full_collections; // ... started
115 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
116 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
117
118 // Reason for current garbage collection. Should be set to
119 // a value reflecting no collection between collections.
120 GCCause::Cause _gc_cause;
121 GCCause::Cause _gc_lastcause;
122 PerfStringVariable* _perf_gc_cause;
123 PerfStringVariable* _perf_gc_lastcause;
124
125 // Constructor
126 CollectedHeap();
127
128 // Create a new tlab. All TLAB allocations must go through this.
129 // To allow more flexible TLAB allocations min_size specifies
130 // the minimum size needed, while requested_size is the requested
131 // size based on ergonomics. The actually allocated size will be
132 // returned in actual_size.
133 virtual HeapWord* allocate_new_tlab(size_t min_size,
134 size_t requested_size,
135 size_t* actual_size);
136
137 // Accumulate statistics on all tlabs.
138 virtual void accumulate_statistics_all_tlabs();
139
140 // Reinitialize tlabs before resuming mutators.
141 virtual void resize_all_tlabs();
142
143 // Allocate from the current thread's TLAB, with broken-out slow path.
144 inline static HeapWord* allocate_from_tlab(Klass* klass, size_t size, TRAPS);
145 static HeapWord* allocate_from_tlab_slow(Klass* klass, size_t size, TRAPS);
146
147 // Raw memory allocation facilities
148 // The obj and array allocate methods are covers for these methods.
149 // mem_allocate() should never be
150 // called to allocate TLABs, only individual objects.
151 virtual HeapWord* mem_allocate(size_t size,
152 bool* gc_overhead_limit_was_exceeded) = 0;
153
154 // Allocate an uninitialized block of the given size, or returns NULL if
155 // this is impossible.
156 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS);
157
158 // Like allocate_init, but the block returned by a successful allocation
159 // is guaranteed initialized to zeros.
160 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS);
161
162 // Helper functions for (VM) allocation.
163 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj);
164 inline static void post_allocation_setup_no_klass_install(Klass* klass,
165 HeapWord* objPtr);
166
167 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size);
168
169 inline static void post_allocation_setup_array(Klass* klass,
170 HeapWord* obj, int length);
171
172 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size);
173
174 // Clears an allocated object.
175 inline static void init_obj(HeapWord* obj, size_t size);
176
177 // Filler object utilities.
178 static inline size_t filler_array_hdr_size();
179 static inline size_t filler_array_min_size();
180
181 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
182 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
183
184 // Fill with a single array; caller must ensure filler_array_min_size() <=
185 // words <= filler_array_max_size().
186 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
187
188 // Fill with a single object (either an int array or a java.lang.Object).
189 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
190
191 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
192
193 // Verification functions
194 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
195 PRODUCT_RETURN;
196 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
197 PRODUCT_RETURN;
198 debug_only(static void check_for_valid_allocation_state();)
199
200 public:
201 enum Name {
202 None,
203 Serial,
204 Parallel,
205 CMS,
206 G1,
207 Epsilon,
208 };
209
210 static inline size_t filler_array_max_size() {
211 return _filler_array_max_size;
212 }
213
214 virtual Name kind() const = 0;
215
216 virtual const char* name() const = 0;
217
218 /**
219 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
220 * and JNI_OK on success.
221 */
222 virtual jint initialize() = 0;
223
224 // In many heaps, there will be a need to perform some initialization activities
225 // after the Universe is fully formed, but before general heap allocation is allowed.
226 // This is the correct place to place such initialization methods.
227 virtual void post_initialize();
228
229 // Stop any onging concurrent work and prepare for exit.
230 virtual void stop() {}
231
232 // Stop and resume concurrent GC threads interfering with safepoint operations
233 virtual void safepoint_synchronize_begin() {}
234 virtual void safepoint_synchronize_end() {}
235
236 void initialize_reserved_region(HeapWord *start, HeapWord *end);
237 MemRegion reserved_region() const { return _reserved; }
238 address base() const { return (address)reserved_region().start(); }
239
240 virtual size_t capacity() const = 0;
241 virtual size_t used() const = 0;
242
243 // Return "true" if the part of the heap that allocates Java
244 // objects has reached the maximal committed limit that it can
245 // reach, without a garbage collection.
246 virtual bool is_maximal_no_gc() const = 0;
247
248 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
249 // memory that the vm could make available for storing 'normal' java objects.
250 // This is based on the reserved address space, but should not include space
251 // that the vm uses internally for bookkeeping or temporary storage
252 // (e.g., in the case of the young gen, one of the survivor
253 // spaces).
254 virtual size_t max_capacity() const = 0;
255
256 // Returns "TRUE" if "p" points into the reserved area of the heap.
257 bool is_in_reserved(const void* p) const {
258 return _reserved.contains(p);
259 }
260
261 bool is_in_reserved_or_null(const void* p) const {
262 return p == NULL || is_in_reserved(p);
263 }
264
265 // Returns "TRUE" iff "p" points into the committed areas of the heap.
266 // This method can be expensive so avoid using it in performance critical
267 // code.
268 virtual bool is_in(const void* p) const = 0;
269
270 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
271
272 // Let's define some terms: a "closed" subset of a heap is one that
273 //
274 // 1) contains all currently-allocated objects, and
275 //
276 // 2) is closed under reference: no object in the closed subset
277 // references one outside the closed subset.
278 //
279 // Membership in a heap's closed subset is useful for assertions.
280 // Clearly, the entire heap is a closed subset, so the default
281 // implementation is to use "is_in_reserved". But this may not be too
282 // liberal to perform useful checking. Also, the "is_in" predicate
283 // defines a closed subset, but may be too expensive, since "is_in"
284 // verifies that its argument points to an object head. The
285 // "closed_subset" method allows a heap to define an intermediate
286 // predicate, allowing more precise checking than "is_in_reserved" at
287 // lower cost than "is_in."
288
289 // One important case is a heap composed of disjoint contiguous spaces,
290 // such as the Garbage-First collector. Such heaps have a convenient
291 // closed subset consisting of the allocated portions of those
292 // contiguous spaces.
293
294 // Return "TRUE" iff the given pointer points into the heap's defined
295 // closed subset (which defaults to the entire heap).
296 virtual bool is_in_closed_subset(const void* p) const {
297 return is_in_reserved(p);
298 }
299
300 bool is_in_closed_subset_or_null(const void* p) const {
301 return p == NULL || is_in_closed_subset(p);
302 }
303
304 void set_gc_cause(GCCause::Cause v) {
305 if (UsePerfData) {
306 _gc_lastcause = _gc_cause;
307 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
308 _perf_gc_cause->set_value(GCCause::to_string(v));
309 }
310 _gc_cause = v;
311 }
312 GCCause::Cause gc_cause() { return _gc_cause; }
313
314 // General obj/array allocation facilities.
315 inline static oop obj_allocate(Klass* klass, int size, TRAPS);
316 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS);
317 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS);
318 inline static oop class_allocate(Klass* klass, int size, TRAPS);
319
320 // Raw memory allocation. This may or may not use TLAB allocations to satisfy the
321 // allocation. A GC implementation may override this function to satisfy the allocation
322 // in any way. But the default is to try a TLAB allocation, and otherwise perform
323 // mem_allocate.
324 virtual HeapWord* obj_allocate_raw(Klass* klass, size_t size,
325 bool* gc_overhead_limit_was_exceeded, TRAPS);
326
327 // Utilities for turning raw memory into filler objects.
328 //
329 // min_fill_size() is the smallest region that can be filled.
330 // fill_with_objects() can fill arbitrary-sized regions of the heap using
331 // multiple objects. fill_with_object() is for regions known to be smaller
332 // than the largest array of integers; it uses a single object to fill the
333 // region and has slightly less overhead.
334 static size_t min_fill_size() {
335 return size_t(align_object_size(oopDesc::header_size()));
336 }
337
338 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
339
340 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
341 static void fill_with_object(MemRegion region, bool zap = true) {
342 fill_with_object(region.start(), region.word_size(), zap);
343 }
344 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
345 fill_with_object(start, pointer_delta(end, start), zap);
346 }
347
348 // Return the address "addr" aligned by "alignment_in_bytes" if such
349 // an address is below "end". Return NULL otherwise.
350 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
351 HeapWord* end,
352 unsigned short alignment_in_bytes);
353
354 // Some heaps may offer a contiguous region for shared non-blocking
355 // allocation, via inlined code (by exporting the address of the top and
356 // end fields defining the extent of the contiguous allocation region.)
357
358 // This function returns "true" iff the heap supports this kind of
359 // allocation. (Default is "no".)
360 virtual bool supports_inline_contig_alloc() const {
361 return false;
362 }
363 // These functions return the addresses of the fields that define the
364 // boundaries of the contiguous allocation area. (These fields should be
365 // physically near to one another.)
366 virtual HeapWord* volatile* top_addr() const {
367 guarantee(false, "inline contiguous allocation not supported");
368 return NULL;
369 }
370 virtual HeapWord** end_addr() const {
371 guarantee(false, "inline contiguous allocation not supported");
372 return NULL;
373 }
374
375 // Some heaps may be in an unparseable state at certain times between
376 // collections. This may be necessary for efficient implementation of
377 // certain allocation-related activities. Calling this function before
378 // attempting to parse a heap ensures that the heap is in a parsable
379 // state (provided other concurrent activity does not introduce
380 // unparsability). It is normally expected, therefore, that this
381 // method is invoked with the world stopped.
382 // NOTE: if you override this method, make sure you call
383 // super::ensure_parsability so that the non-generational
384 // part of the work gets done. See implementation of
385 // CollectedHeap::ensure_parsability and, for instance,
386 // that of GenCollectedHeap::ensure_parsability().
387 // The argument "retire_tlabs" controls whether existing TLABs
388 // are merely filled or also retired, thus preventing further
389 // allocation from them and necessitating allocation of new TLABs.
390 virtual void ensure_parsability(bool retire_tlabs);
391
392 // Section on thread-local allocation buffers (TLABs)
393 // If the heap supports thread-local allocation buffers, it should override
394 // the following methods:
395 // Returns "true" iff the heap supports thread-local allocation buffers.
396 // The default is "no".
397 virtual bool supports_tlab_allocation() const = 0;
398
399 // The amount of space available for thread-local allocation buffers.
400 virtual size_t tlab_capacity(Thread *thr) const = 0;
401
402 // The amount of used space for thread-local allocation buffers for the given thread.
403 virtual size_t tlab_used(Thread *thr) const = 0;
404
405 virtual size_t max_tlab_size() const;
406
407 // An estimate of the maximum allocation that could be performed
408 // for thread-local allocation buffers without triggering any
409 // collection or expansion activity.
410 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
411 guarantee(false, "thread-local allocation buffers not supported");
412 return 0;
413 }
414
415 // Perform a collection of the heap; intended for use in implementing
416 // "System.gc". This probably implies as full a collection as the
417 // "CollectedHeap" supports.
418 virtual void collect(GCCause::Cause cause) = 0;
419
420 // Perform a full collection
421 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
422
423 // This interface assumes that it's being called by the
424 // vm thread. It collects the heap assuming that the
425 // heap lock is already held and that we are executing in
426 // the context of the vm thread.
427 virtual void collect_as_vm_thread(GCCause::Cause cause);
428
429 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
430 size_t size,
431 Metaspace::MetadataType mdtype);
432
433 // Returns "true" iff there is a stop-world GC in progress. (I assume
434 // that it should answer "false" for the concurrent part of a concurrent
435 // collector -- dld).
436 bool is_gc_active() const { return _is_gc_active; }
437
438 // Total number of GC collections (started)
439 unsigned int total_collections() const { return _total_collections; }
440 unsigned int total_full_collections() const { return _total_full_collections;}
441
442 // Increment total number of GC collections (started)
443 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
444 void increment_total_collections(bool full = false) {
445 _total_collections++;
446 if (full) {
447 increment_total_full_collections();
448 }
449 }
450
451 void increment_total_full_collections() { _total_full_collections++; }
452
453 // Return the CollectorPolicy for the heap
454 virtual CollectorPolicy* collector_policy() const = 0;
455
456 // Return the SoftRefPolicy for the heap;
457 virtual SoftRefPolicy* soft_ref_policy() = 0;
458
459 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
460 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
461
462 // Iterate over all objects, calling "cl.do_object" on each.
463 virtual void object_iterate(ObjectClosure* cl) = 0;
464
465 // Similar to object_iterate() except iterates only
466 // over live objects.
467 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
468
469 // NOTE! There is no requirement that a collector implement these
470 // functions.
471 //
472 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
473 // each address in the (reserved) heap is a member of exactly
474 // one block. The defining characteristic of a block is that it is
475 // possible to find its size, and thus to progress forward to the next
476 // block. (Blocks may be of different sizes.) Thus, blocks may
477 // represent Java objects, or they might be free blocks in a
478 // free-list-based heap (or subheap), as long as the two kinds are
479 // distinguishable and the size of each is determinable.
480
481 // Returns the address of the start of the "block" that contains the
482 // address "addr". We say "blocks" instead of "object" since some heaps
483 // may not pack objects densely; a chunk may either be an object or a
484 // non-object.
485 virtual HeapWord* block_start(const void* addr) const = 0;
486
487 // Requires "addr" to be the start of a chunk, and returns its size.
488 // "addr + size" is required to be the start of a new chunk, or the end
489 // of the active area of the heap.
490 virtual size_t block_size(const HeapWord* addr) const = 0;
491
492 // Requires "addr" to be the start of a block, and returns "TRUE" iff
493 // the block is an object.
494 virtual bool block_is_obj(const HeapWord* addr) const = 0;
495
496 // Returns the longest time (in ms) that has elapsed since the last
497 // time that any part of the heap was examined by a garbage collection.
498 virtual jlong millis_since_last_gc() = 0;
499
500 // Perform any cleanup actions necessary before allowing a verification.
501 virtual void prepare_for_verify() = 0;
502
503 // Generate any dumps preceding or following a full gc
504 private:
505 void full_gc_dump(GCTimer* timer, bool before);
506
507 virtual void initialize_serviceability() = 0;
508
509 public:
510 void pre_full_gc_dump(GCTimer* timer);
511 void post_full_gc_dump(GCTimer* timer);
512
513 virtual VirtualSpaceSummary create_heap_space_summary();
514 GCHeapSummary create_heap_summary();
515
516 MetaspaceSummary create_metaspace_summary();
517
518 // Print heap information on the given outputStream.
519 virtual void print_on(outputStream* st) const = 0;
520 // The default behavior is to call print_on() on tty.
521 virtual void print() const {
522 print_on(tty);
523 }
524 // Print more detailed heap information on the given
525 // outputStream. The default behavior is to call print_on(). It is
526 // up to each subclass to override it and add any additional output
527 // it needs.
528 virtual void print_extended_on(outputStream* st) const {
529 print_on(st);
530 }
531
532 virtual void print_on_error(outputStream* st) const;
533
534 // Print all GC threads (other than the VM thread)
535 // used by this heap.
536 virtual void print_gc_threads_on(outputStream* st) const = 0;
537 // The default behavior is to call print_gc_threads_on() on tty.
538 void print_gc_threads() {
539 print_gc_threads_on(tty);
540 }
541 // Iterator for all GC threads (other than VM thread)
542 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
543
544 // Print any relevant tracing info that flags imply.
545 // Default implementation does nothing.
546 virtual void print_tracing_info() const = 0;
547
548 void print_heap_before_gc();
549 void print_heap_after_gc();
550
551 // An object is scavengable if its location may move during a scavenge.
552 // (A scavenge is a GC which is not a full GC.)
553 virtual bool is_scavengable(oop obj) = 0;
554 // Registering and unregistering an nmethod (compiled code) with the heap.
555 // Override with specific mechanism for each specialized heap type.
556 virtual void register_nmethod(nmethod* nm) {}
557 virtual void unregister_nmethod(nmethod* nm) {}
558 virtual void verify_nmethod(nmethod* nmethod) {}
559
560 void trace_heap_before_gc(const GCTracer* gc_tracer);
561 void trace_heap_after_gc(const GCTracer* gc_tracer);
562
563 // Heap verification
564 virtual void verify(VerifyOption option) = 0;
565
566 // Return true if concurrent phase control (via
567 // request_concurrent_phase_control) is supported by this collector.
568 // The default implementation returns false.
569 virtual bool supports_concurrent_phase_control() const;
570
571 // Return a NULL terminated array of concurrent phase names provided
572 // by this collector. Supports Whitebox testing. These are the
573 // names recognized by request_concurrent_phase(). The default
574 // implementation returns an array of one NULL element.
575 virtual const char* const* concurrent_phases() const;
576
577 // Request the collector enter the indicated concurrent phase, and
578 // wait until it does so. Supports WhiteBox testing. Only one
579 // request may be active at a time. Phases are designated by name;
580 // the set of names and their meaning is GC-specific. Once the
581 // requested phase has been reached, the collector will attempt to
582 // avoid transitioning to a new phase until a new request is made.
583 // [Note: A collector might not be able to remain in a given phase.
584 // For example, a full collection might cancel an in-progress
585 // concurrent collection.]
586 //
587 // Returns true when the phase is reached. Returns false for an
588 // unknown phase. The default implementation returns false.
589 virtual bool request_concurrent_phase(const char* phase);
590
591 // Provides a thread pool to SafepointSynchronize to use
592 // for parallel safepoint cleanup.
593 // GCs that use a GC worker thread pool may want to share
594 // it for use during safepoint cleanup. This is only possible
595 // if the GC can pause and resume concurrent work (e.g. G1
596 // concurrent marking) for an intermittent non-GC safepoint.
597 // If this method returns NULL, SafepointSynchronize will
598 // perform cleanup tasks serially in the VMThread.
599 virtual WorkGang* get_safepoint_workers() { return NULL; }
600
601 // Support for object pinning. This is used by JNI Get*Critical()
602 // and Release*Critical() family of functions. If supported, the GC
603 // must guarantee that pinned objects never move.
604 virtual bool supports_object_pinning() const;
605 virtual oop pin_object(JavaThread* thread, oop obj);
606 virtual void unpin_object(JavaThread* thread, oop obj);
607
608 // Deduplicate the string, iff the GC supports string deduplication.
609 virtual void deduplicate_string(oop str);
610
611 virtual bool is_oop(oop object) const;
612
613 // Non product verification and debugging.
614 #ifndef PRODUCT
615 // Support for PromotionFailureALot. Return true if it's time to cause a
616 // promotion failure. The no-argument version uses
617 // this->_promotion_failure_alot_count as the counter.
618 bool promotion_should_fail(volatile size_t* count);
619 bool promotion_should_fail();
620
621 // Reset the PromotionFailureALot counters. Should be called at the end of a
622 // GC in which promotion failure occurred.
623 void reset_promotion_should_fail(volatile size_t* count);
624 void reset_promotion_should_fail();
625 #endif // #ifndef PRODUCT
626
627 #ifdef ASSERT
628 static int fired_fake_oom() {
629 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
630 }
631 #endif
632 };
633
634 // Class to set and reset the GC cause for a CollectedHeap.
635
636 class GCCauseSetter : StackObj {
637 CollectedHeap* _heap;
638 GCCause::Cause _previous_cause;
639 public:
640 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
641 _heap = heap;
642 _previous_cause = _heap->gc_cause();
643 _heap->set_gc_cause(cause);
644 }
645
646 ~GCCauseSetter() {
647 _heap->set_gc_cause(_previous_cause);
648 }
649 };
650
651 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP