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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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 #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 inline static HeapWord* allocate_outside_tlab(Klass* klass, size_t size,
148 bool* gc_overhead_limit_was_exceeded, TRAPS);
149
150 // Raw memory allocation facilities
151 // The obj and array allocate methods are covers for these methods.
152 // mem_allocate() should never be
153 // called to allocate TLABs, only individual objects.
154 virtual HeapWord* mem_allocate(size_t size,
155 bool* gc_overhead_limit_was_exceeded) = 0;
156
157 // Allocate an uninitialized block of the given size, or returns NULL if
158 // this is impossible.
159 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS);
160
161 // Like allocate_init, but the block returned by a successful allocation
162 // is guaranteed initialized to zeros.
163 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS);
164
165 // Helper functions for (VM) allocation.
166 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj);
167 inline static void post_allocation_setup_no_klass_install(Klass* klass,
168 HeapWord* objPtr);
169
170 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size);
171
172 inline static void post_allocation_setup_array(Klass* klass,
173 HeapWord* obj, int length);
174
175 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size);
176
177 // Clears an allocated object.
178 inline static void init_obj(HeapWord* obj, size_t size);
179
180 // Filler object utilities.
181 static inline size_t filler_array_hdr_size();
182 static inline size_t filler_array_min_size();
183
184 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
185 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
186
187 // Fill with a single array; caller must ensure filler_array_min_size() <=
188 // words <= filler_array_max_size().
189 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
190
191 // Fill with a single object (either an int array or a java.lang.Object).
192 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
193
194 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
195
196 // Verification functions
197 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
198 PRODUCT_RETURN;
199 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
200 PRODUCT_RETURN;
201 debug_only(static void check_for_valid_allocation_state();)
202
203 public:
204 enum Name {
205 None,
206 Serial,
207 Parallel,
208 CMS,
209 G1,
210 Epsilon,
211 };
212
213 static inline size_t filler_array_max_size() {
214 return _filler_array_max_size;
215 }
216
217 virtual Name kind() const = 0;
218
219 virtual const char* name() const = 0;
220
221 /**
222 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
223 * and JNI_OK on success.
224 */
225 virtual jint initialize() = 0;
226
227 // In many heaps, there will be a need to perform some initialization activities
228 // after the Universe is fully formed, but before general heap allocation is allowed.
229 // This is the correct place to place such initialization methods.
230 virtual void post_initialize();
231
232 // Stop any onging concurrent work and prepare for exit.
233 virtual void stop() {}
234
235 // Stop and resume concurrent GC threads interfering with safepoint operations
236 virtual void safepoint_synchronize_begin() {}
237 virtual void safepoint_synchronize_end() {}
238
239 void initialize_reserved_region(HeapWord *start, HeapWord *end);
240 MemRegion reserved_region() const { return _reserved; }
241 address base() const { return (address)reserved_region().start(); }
242
243 virtual size_t capacity() const = 0;
244 virtual size_t used() const = 0;
245
246 // Return "true" if the part of the heap that allocates Java
247 // objects has reached the maximal committed limit that it can
248 // reach, without a garbage collection.
249 virtual bool is_maximal_no_gc() const = 0;
250
251 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
252 // memory that the vm could make available for storing 'normal' java objects.
253 // This is based on the reserved address space, but should not include space
254 // that the vm uses internally for bookkeeping or temporary storage
255 // (e.g., in the case of the young gen, one of the survivor
256 // spaces).
257 virtual size_t max_capacity() const = 0;
258
259 // Returns "TRUE" if "p" points into the reserved area of the heap.
260 bool is_in_reserved(const void* p) const {
261 return _reserved.contains(p);
262 }
263
264 bool is_in_reserved_or_null(const void* p) const {
265 return p == NULL || is_in_reserved(p);
266 }
267
268 // Returns "TRUE" iff "p" points into the committed areas of the heap.
269 // This method can be expensive so avoid using it in performance critical
270 // code.
271 virtual bool is_in(const void* p) const = 0;
272
273 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
274
275 // Let's define some terms: a "closed" subset of a heap is one that
276 //
277 // 1) contains all currently-allocated objects, and
278 //
279 // 2) is closed under reference: no object in the closed subset
280 // references one outside the closed subset.
281 //
282 // Membership in a heap's closed subset is useful for assertions.
283 // Clearly, the entire heap is a closed subset, so the default
284 // implementation is to use "is_in_reserved". But this may not be too
285 // liberal to perform useful checking. Also, the "is_in" predicate
286 // defines a closed subset, but may be too expensive, since "is_in"
287 // verifies that its argument points to an object head. The
288 // "closed_subset" method allows a heap to define an intermediate
289 // predicate, allowing more precise checking than "is_in_reserved" at
290 // lower cost than "is_in."
291
292 // One important case is a heap composed of disjoint contiguous spaces,
293 // such as the Garbage-First collector. Such heaps have a convenient
294 // closed subset consisting of the allocated portions of those
295 // contiguous spaces.
296
297 // Return "TRUE" iff the given pointer points into the heap's defined
298 // closed subset (which defaults to the entire heap).
299 virtual bool is_in_closed_subset(const void* p) const {
300 return is_in_reserved(p);
301 }
302
303 bool is_in_closed_subset_or_null(const void* p) const {
304 return p == NULL || is_in_closed_subset(p);
305 }
306
307 void set_gc_cause(GCCause::Cause v) {
308 if (UsePerfData) {
309 _gc_lastcause = _gc_cause;
310 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
311 _perf_gc_cause->set_value(GCCause::to_string(v));
312 }
313 _gc_cause = v;
314 }
315 GCCause::Cause gc_cause() { return _gc_cause; }
316
317 // General obj/array allocation facilities.
318 inline static oop obj_allocate(Klass* klass, int size, TRAPS);
319 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS);
320 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS);
321 inline static oop class_allocate(Klass* klass, int size, TRAPS);
322
323 // Raw memory allocation. This may or may not use TLAB allocations to satisfy the
324 // allocation. A GC implementation may override this function to satisfy the allocation
325 // in any way. But the default is to try a TLAB allocation, and otherwise perform
326 // mem_allocate.
327 virtual HeapWord* obj_allocate_raw(Klass* klass, size_t size,
328 bool* gc_overhead_limit_was_exceeded, TRAPS);
329
330 // Utilities for turning raw memory into filler objects.
331 //
332 // min_fill_size() is the smallest region that can be filled.
333 // fill_with_objects() can fill arbitrary-sized regions of the heap using
334 // multiple objects. fill_with_object() is for regions known to be smaller
335 // than the largest array of integers; it uses a single object to fill the
336 // region and has slightly less overhead.
337 static size_t min_fill_size() {
338 return size_t(align_object_size(oopDesc::header_size()));
339 }
340
341 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
342
343 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
344 static void fill_with_object(MemRegion region, bool zap = true) {
345 fill_with_object(region.start(), region.word_size(), zap);
346 }
347 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
348 fill_with_object(start, pointer_delta(end, start), zap);
349 }
350
351 // Return the address "addr" aligned by "alignment_in_bytes" if such
352 // an address is below "end". Return NULL otherwise.
353 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
354 HeapWord* end,
355 unsigned short alignment_in_bytes);
356
357 // Some heaps may offer a contiguous region for shared non-blocking
358 // allocation, via inlined code (by exporting the address of the top and
359 // end fields defining the extent of the contiguous allocation region.)
360
361 // This function returns "true" iff the heap supports this kind of
362 // allocation. (Default is "no".)
363 virtual bool supports_inline_contig_alloc() const {
364 return false;
365 }
366 // These functions return the addresses of the fields that define the
367 // boundaries of the contiguous allocation area. (These fields should be
368 // physically near to one another.)
369 virtual HeapWord* volatile* top_addr() const {
370 guarantee(false, "inline contiguous allocation not supported");
371 return NULL;
372 }
373 virtual HeapWord** end_addr() const {
374 guarantee(false, "inline contiguous allocation not supported");
375 return NULL;
376 }
377
378 // Some heaps may be in an unparseable state at certain times between
379 // collections. This may be necessary for efficient implementation of
380 // certain allocation-related activities. Calling this function before
381 // attempting to parse a heap ensures that the heap is in a parsable
382 // state (provided other concurrent activity does not introduce
383 // unparsability). It is normally expected, therefore, that this
384 // method is invoked with the world stopped.
385 // NOTE: if you override this method, make sure you call
386 // super::ensure_parsability so that the non-generational
387 // part of the work gets done. See implementation of
388 // CollectedHeap::ensure_parsability and, for instance,
389 // that of GenCollectedHeap::ensure_parsability().
390 // The argument "retire_tlabs" controls whether existing TLABs
391 // are merely filled or also retired, thus preventing further
392 // allocation from them and necessitating allocation of new TLABs.
393 virtual void ensure_parsability(bool retire_tlabs);
394
395 // Section on thread-local allocation buffers (TLABs)
396 // If the heap supports thread-local allocation buffers, it should override
397 // the following methods:
398 // Returns "true" iff the heap supports thread-local allocation buffers.
399 // The default is "no".
400 virtual bool supports_tlab_allocation() const = 0;
401
402 // The amount of space available for thread-local allocation buffers.
403 virtual size_t tlab_capacity(Thread *thr) const = 0;
404
405 // The amount of used space for thread-local allocation buffers for the given thread.
406 virtual size_t tlab_used(Thread *thr) const = 0;
407
408 virtual size_t max_tlab_size() const;
409
410 // An estimate of the maximum allocation that could be performed
411 // for thread-local allocation buffers without triggering any
412 // collection or expansion activity.
413 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
414 guarantee(false, "thread-local allocation buffers not supported");
415 return 0;
416 }
417
418 // Perform a collection of the heap; intended for use in implementing
419 // "System.gc". This probably implies as full a collection as the
420 // "CollectedHeap" supports.
421 virtual void collect(GCCause::Cause cause) = 0;
422
423 // Perform a full collection
424 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
425
426 // This interface assumes that it's being called by the
427 // vm thread. It collects the heap assuming that the
428 // heap lock is already held and that we are executing in
429 // the context of the vm thread.
430 virtual void collect_as_vm_thread(GCCause::Cause cause);
431
432 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
433 size_t size,
434 Metaspace::MetadataType mdtype);
435
436 // Returns "true" iff there is a stop-world GC in progress. (I assume
437 // that it should answer "false" for the concurrent part of a concurrent
438 // collector -- dld).
439 bool is_gc_active() const { return _is_gc_active; }
440
441 // Total number of GC collections (started)
442 unsigned int total_collections() const { return _total_collections; }
443 unsigned int total_full_collections() const { return _total_full_collections;}
444
445 // Increment total number of GC collections (started)
446 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
447 void increment_total_collections(bool full = false) {
448 _total_collections++;
449 if (full) {
450 increment_total_full_collections();
451 }
452 }
453
454 void increment_total_full_collections() { _total_full_collections++; }
455
456 // Return the CollectorPolicy for the heap
457 virtual CollectorPolicy* collector_policy() const = 0;
458
459 // Return the SoftRefPolicy for the heap;
460 virtual SoftRefPolicy* soft_ref_policy() = 0;
461
462 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
463 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
464
465 // Iterate over all objects, calling "cl.do_object" on each.
466 virtual void object_iterate(ObjectClosure* cl) = 0;
467
468 // Similar to object_iterate() except iterates only
469 // over live objects.
470 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
471
472 // NOTE! There is no requirement that a collector implement these
473 // functions.
474 //
475 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
476 // each address in the (reserved) heap is a member of exactly
477 // one block. The defining characteristic of a block is that it is
478 // possible to find its size, and thus to progress forward to the next
479 // block. (Blocks may be of different sizes.) Thus, blocks may
480 // represent Java objects, or they might be free blocks in a
481 // free-list-based heap (or subheap), as long as the two kinds are
482 // distinguishable and the size of each is determinable.
483
484 // Returns the address of the start of the "block" that contains the
485 // address "addr". We say "blocks" instead of "object" since some heaps
486 // may not pack objects densely; a chunk may either be an object or a
487 // non-object.
488 virtual HeapWord* block_start(const void* addr) const = 0;
489
490 // Requires "addr" to be the start of a chunk, and returns its size.
491 // "addr + size" is required to be the start of a new chunk, or the end
492 // of the active area of the heap.
493 virtual size_t block_size(const HeapWord* addr) const = 0;
494
495 // Requires "addr" to be the start of a block, and returns "TRUE" iff
496 // the block is an object.
497 virtual bool block_is_obj(const HeapWord* addr) const = 0;
498
499 // Returns the longest time (in ms) that has elapsed since the last
500 // time that any part of the heap was examined by a garbage collection.
501 virtual jlong millis_since_last_gc() = 0;
502
503 // Perform any cleanup actions necessary before allowing a verification.
504 virtual void prepare_for_verify() = 0;
505
506 // Generate any dumps preceding or following a full gc
507 private:
508 void full_gc_dump(GCTimer* timer, bool before);
509
510 virtual void initialize_serviceability() = 0;
511
512 public:
513 void pre_full_gc_dump(GCTimer* timer);
514 void post_full_gc_dump(GCTimer* timer);
515
516 virtual VirtualSpaceSummary create_heap_space_summary();
517 GCHeapSummary create_heap_summary();
518
519 MetaspaceSummary create_metaspace_summary();
520
521 // Print heap information on the given outputStream.
522 virtual void print_on(outputStream* st) const = 0;
523 // The default behavior is to call print_on() on tty.
524 virtual void print() const {
525 print_on(tty);
526 }
527 // Print more detailed heap information on the given
528 // outputStream. The default behavior is to call print_on(). It is
529 // up to each subclass to override it and add any additional output
530 // it needs.
531 virtual void print_extended_on(outputStream* st) const {
532 print_on(st);
533 }
534
535 virtual void print_on_error(outputStream* st) const;
536
537 // Print all GC threads (other than the VM thread)
538 // used by this heap.
539 virtual void print_gc_threads_on(outputStream* st) const = 0;
540 // The default behavior is to call print_gc_threads_on() on tty.
541 void print_gc_threads() {
542 print_gc_threads_on(tty);
543 }
544 // Iterator for all GC threads (other than VM thread)
545 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
546
547 // Print any relevant tracing info that flags imply.
548 // Default implementation does nothing.
549 virtual void print_tracing_info() const = 0;
550
551 void print_heap_before_gc();
552 void print_heap_after_gc();
553
554 // An object is scavengable if its location may move during a scavenge.
555 // (A scavenge is a GC which is not a full GC.)
556 virtual bool is_scavengable(oop obj) = 0;
557 // Registering and unregistering an nmethod (compiled code) with the heap.
558 // Override with specific mechanism for each specialized heap type.
559 virtual void register_nmethod(nmethod* nm) {}
560 virtual void unregister_nmethod(nmethod* nm) {}
561 virtual void verify_nmethod(nmethod* nmethod) {}
562
563 void trace_heap_before_gc(const GCTracer* gc_tracer);
564 void trace_heap_after_gc(const GCTracer* gc_tracer);
565
566 // Heap verification
567 virtual void verify(VerifyOption option) = 0;
568
569 // Return true if concurrent phase control (via
570 // request_concurrent_phase_control) is supported by this collector.
571 // The default implementation returns false.
572 virtual bool supports_concurrent_phase_control() const;
573
574 // Return a NULL terminated array of concurrent phase names provided
575 // by this collector. Supports Whitebox testing. These are the
576 // names recognized by request_concurrent_phase(). The default
577 // implementation returns an array of one NULL element.
578 virtual const char* const* concurrent_phases() const;
579
580 // Request the collector enter the indicated concurrent phase, and
581 // wait until it does so. Supports WhiteBox testing. Only one
582 // request may be active at a time. Phases are designated by name;
583 // the set of names and their meaning is GC-specific. Once the
584 // requested phase has been reached, the collector will attempt to
585 // avoid transitioning to a new phase until a new request is made.
586 // [Note: A collector might not be able to remain in a given phase.
587 // For example, a full collection might cancel an in-progress
588 // concurrent collection.]
589 //
590 // Returns true when the phase is reached. Returns false for an
591 // unknown phase. The default implementation returns false.
592 virtual bool request_concurrent_phase(const char* phase);
593
594 // Provides a thread pool to SafepointSynchronize to use
595 // for parallel safepoint cleanup.
596 // GCs that use a GC worker thread pool may want to share
597 // it for use during safepoint cleanup. This is only possible
598 // if the GC can pause and resume concurrent work (e.g. G1
599 // concurrent marking) for an intermittent non-GC safepoint.
600 // If this method returns NULL, SafepointSynchronize will
601 // perform cleanup tasks serially in the VMThread.
602 virtual WorkGang* get_safepoint_workers() { return NULL; }
603
604 // Support for object pinning. This is used by JNI Get*Critical()
605 // and Release*Critical() family of functions. If supported, the GC
606 // must guarantee that pinned objects never move.
607 virtual bool supports_object_pinning() const;
608 virtual oop pin_object(JavaThread* thread, oop obj);
609 virtual void unpin_object(JavaThread* thread, oop obj);
610
611 // Deduplicate the string, iff the GC supports string deduplication.
612 virtual void deduplicate_string(oop str);
613
614 virtual bool is_oop(oop object) const;
615
616 // Non product verification and debugging.
617 #ifndef PRODUCT
618 // Support for PromotionFailureALot. Return true if it's time to cause a
619 // promotion failure. The no-argument version uses
620 // this->_promotion_failure_alot_count as the counter.
621 bool promotion_should_fail(volatile size_t* count);
622 bool promotion_should_fail();
623
624 // Reset the PromotionFailureALot counters. Should be called at the end of a
625 // GC in which promotion failure occurred.
626 void reset_promotion_should_fail(volatile size_t* count);
627 void reset_promotion_should_fail();
628 #endif // #ifndef PRODUCT
629
630 #ifdef ASSERT
631 static int fired_fake_oom() {
632 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
633 }
634 #endif
635 };
636
637 // Class to set and reset the GC cause for a CollectedHeap.
638
639 class GCCauseSetter : StackObj {
640 CollectedHeap* _heap;
641 GCCause::Cause _previous_cause;
642 public:
643 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
644 _heap = heap;
645 _previous_cause = _heap->gc_cause();
646 _heap->set_gc_cause(cause);
647 }
648
649 ~GCCauseSetter() {
650 _heap->set_gc_cause(_previous_cause);
651 }
652 };
653
654 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP