1 /*
2 * Copyright (c) 2001, 2017, 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
38 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
39 // is an abstract class: there may be many different kinds of heaps. This
40 // class defines the functions that a heap must implement, and contains
41 // infrastructure common to all heaps.
42
43 class AdaptiveSizePolicy;
44 class BarrierSet;
45 class CollectorPolicy;
46 class GCHeapSummary;
47 class GCTimer;
48 class GCTracer;
49 class MetaspaceSummary;
50 class Thread;
51 class ThreadClosure;
52 class VirtualSpaceSummary;
53 class nmethod;
54
55 class GCMessage : public FormatBuffer<1024> {
56 public:
57 bool is_before;
58
59 public:
60 GCMessage() {}
61 };
62
63 class CollectedHeap;
64
65 class GCHeapLog : public EventLogBase<GCMessage> {
66 private:
67 void log_heap(CollectedHeap* heap, bool before);
68
69 public:
70 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
71
72 void log_heap_before(CollectedHeap* heap) {
73 log_heap(heap, true);
74 }
75 void log_heap_after(CollectedHeap* heap) {
76 log_heap(heap, false);
77 }
78 };
79
80 //
81 // CollectedHeap
82 // GenCollectedHeap
83 // G1CollectedHeap
84 // ParallelScavengeHeap
85 // CMSHeap
86 //
87 class CollectedHeap : public CHeapObj<mtInternal> {
88 friend class VMStructs;
89 friend class JVMCIVMStructs;
90 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
91
92 private:
93 #ifdef ASSERT
94 static int _fire_out_of_memory_count;
95 #endif
96
97 GCHeapLog* _gc_heap_log;
98
99 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2
100 // or INCLUDE_JVMCI is being used
101 bool _defer_initial_card_mark;
102
103 MemRegion _reserved;
104
105 protected:
106 BarrierSet* _barrier_set;
107 bool _is_gc_active;
108
109 // Used for filler objects (static, but initialized in ctor).
110 static size_t _filler_array_max_size;
111
112 unsigned int _total_collections; // ... started
113 unsigned int _total_full_collections; // ... started
114 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
115 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
116
117 // Reason for current garbage collection. Should be set to
118 // a value reflecting no collection between collections.
119 GCCause::Cause _gc_cause;
120 GCCause::Cause _gc_lastcause;
121 PerfStringVariable* _perf_gc_cause;
122 PerfStringVariable* _perf_gc_lastcause;
123
124 // Constructor
125 CollectedHeap();
126
127 // Do common initializations that must follow instance construction,
128 // for example, those needing virtual calls.
129 // This code could perhaps be moved into initialize() but would
130 // be slightly more awkward because we want the latter to be a
131 // pure virtual.
132 void pre_initialize();
133
134 // Create a new tlab. All TLAB allocations must go through this.
135 virtual HeapWord* allocate_new_tlab(size_t 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, Thread* thread, size_t size);
145 static HeapWord* allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size);
146
147 // Allocate an uninitialized block of the given size, or returns NULL if
148 // this is impossible.
149 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS);
150
151 // Like allocate_init, but the block returned by a successful allocation
152 // is guaranteed initialized to zeros.
153 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS);
154
155 // Helper functions for (VM) allocation.
156 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj);
157 inline static void post_allocation_setup_no_klass_install(Klass* klass,
158 HeapWord* objPtr);
159
160 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size);
161
162 inline static void post_allocation_setup_array(Klass* klass,
163 HeapWord* obj, int length);
164
165 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size);
166
167 // Clears an allocated object.
168 inline static void init_obj(HeapWord* obj, size_t size);
169
170 // Filler object utilities.
171 static inline size_t filler_array_hdr_size();
172 static inline size_t filler_array_min_size();
173
174 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
175 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
176
177 // Fill with a single array; caller must ensure filler_array_min_size() <=
178 // words <= filler_array_max_size().
179 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
180
181 // Fill with a single object (either an int array or a java.lang.Object).
182 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
183
184 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
185
186 // Verification functions
187 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
188 PRODUCT_RETURN;
189 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
190 PRODUCT_RETURN;
191 debug_only(static void check_for_valid_allocation_state();)
192
193 public:
194 enum Name {
195 GenCollectedHeap,
196 ParallelScavengeHeap,
197 G1CollectedHeap,
198 CMSHeap
199 };
200
201 static inline size_t filler_array_max_size() {
202 return _filler_array_max_size;
203 }
204
205 virtual Name kind() const = 0;
206
207 virtual const char* name() const = 0;
208
209 /**
210 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
211 * and JNI_OK on success.
212 */
213 virtual jint initialize() = 0;
214
215 // In many heaps, there will be a need to perform some initialization activities
216 // after the Universe is fully formed, but before general heap allocation is allowed.
217 // This is the correct place to place such initialization methods.
218 virtual void post_initialize() = 0;
219
220 // Stop any onging concurrent work and prepare for exit.
221 virtual void stop() {}
222
223 void initialize_reserved_region(HeapWord *start, HeapWord *end);
224 MemRegion reserved_region() const { return _reserved; }
225 address base() const { return (address)reserved_region().start(); }
226
227 virtual size_t capacity() const = 0;
228 virtual size_t used() const = 0;
229
230 // Return "true" if the part of the heap that allocates Java
231 // objects has reached the maximal committed limit that it can
232 // reach, without a garbage collection.
233 virtual bool is_maximal_no_gc() const = 0;
234
235 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
236 // memory that the vm could make available for storing 'normal' java objects.
237 // This is based on the reserved address space, but should not include space
238 // that the vm uses internally for bookkeeping or temporary storage
239 // (e.g., in the case of the young gen, one of the survivor
240 // spaces).
241 virtual size_t max_capacity() const = 0;
242
243 // Returns "TRUE" if "p" points into the reserved area of the heap.
244 bool is_in_reserved(const void* p) const {
245 return _reserved.contains(p);
246 }
247
248 bool is_in_reserved_or_null(const void* p) const {
249 return p == NULL || is_in_reserved(p);
250 }
251
252 // Returns "TRUE" iff "p" points into the committed areas of the heap.
253 // This method can be expensive so avoid using it in performance critical
254 // code.
255 virtual bool is_in(const void* p) const = 0;
256
257 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
258
259 // Let's define some terms: a "closed" subset of a heap is one that
260 //
261 // 1) contains all currently-allocated objects, and
262 //
263 // 2) is closed under reference: no object in the closed subset
264 // references one outside the closed subset.
265 //
266 // Membership in a heap's closed subset is useful for assertions.
267 // Clearly, the entire heap is a closed subset, so the default
268 // implementation is to use "is_in_reserved". But this may not be too
269 // liberal to perform useful checking. Also, the "is_in" predicate
270 // defines a closed subset, but may be too expensive, since "is_in"
271 // verifies that its argument points to an object head. The
272 // "closed_subset" method allows a heap to define an intermediate
273 // predicate, allowing more precise checking than "is_in_reserved" at
274 // lower cost than "is_in."
275
276 // One important case is a heap composed of disjoint contiguous spaces,
277 // such as the Garbage-First collector. Such heaps have a convenient
278 // closed subset consisting of the allocated portions of those
279 // contiguous spaces.
280
281 // Return "TRUE" iff the given pointer points into the heap's defined
282 // closed subset (which defaults to the entire heap).
283 virtual bool is_in_closed_subset(const void* p) const {
284 return is_in_reserved(p);
285 }
286
287 bool is_in_closed_subset_or_null(const void* p) const {
288 return p == NULL || is_in_closed_subset(p);
289 }
290
291 // An object is scavengable if its location may move during a scavenge.
292 // (A scavenge is a GC which is not a full GC.)
293 virtual bool is_scavengable(const void *p) = 0;
294
295 void set_gc_cause(GCCause::Cause v) {
296 if (UsePerfData) {
297 _gc_lastcause = _gc_cause;
298 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
299 _perf_gc_cause->set_value(GCCause::to_string(v));
300 }
301 _gc_cause = v;
302 }
303 GCCause::Cause gc_cause() { return _gc_cause; }
304
305 // General obj/array allocation facilities.
306 inline static oop obj_allocate(Klass* klass, int size, TRAPS);
307 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS);
308 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS);
309 inline static oop class_allocate(Klass* klass, int size, TRAPS);
310
311 // Raw memory allocation facilities
312 // The obj and array allocate methods are covers for these methods.
313 // mem_allocate() should never be
314 // called to allocate TLABs, only individual objects.
315 virtual HeapWord* mem_allocate(size_t size,
316 bool* gc_overhead_limit_was_exceeded) = 0;
317
318 // Utilities for turning raw memory into filler objects.
319 //
320 // min_fill_size() is the smallest region that can be filled.
321 // fill_with_objects() can fill arbitrary-sized regions of the heap using
322 // multiple objects. fill_with_object() is for regions known to be smaller
323 // than the largest array of integers; it uses a single object to fill the
324 // region and has slightly less overhead.
325 static size_t min_fill_size() {
326 return size_t(align_object_size(oopDesc::header_size()));
327 }
328
329 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
330
331 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
332 static void fill_with_object(MemRegion region, bool zap = true) {
333 fill_with_object(region.start(), region.word_size(), zap);
334 }
335 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
336 fill_with_object(start, pointer_delta(end, start), zap);
337 }
338
339 // Return the address "addr" aligned by "alignment_in_bytes" if such
340 // an address is below "end". Return NULL otherwise.
341 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
342 HeapWord* end,
343 unsigned short alignment_in_bytes);
344
345 // Some heaps may offer a contiguous region for shared non-blocking
346 // allocation, via inlined code (by exporting the address of the top and
347 // end fields defining the extent of the contiguous allocation region.)
348
349 // This function returns "true" iff the heap supports this kind of
350 // allocation. (Default is "no".)
351 virtual bool supports_inline_contig_alloc() const {
352 return false;
353 }
354 // These functions return the addresses of the fields that define the
355 // boundaries of the contiguous allocation area. (These fields should be
356 // physically near to one another.)
357 virtual HeapWord* volatile* top_addr() const {
358 guarantee(false, "inline contiguous allocation not supported");
359 return NULL;
360 }
361 virtual HeapWord** end_addr() const {
362 guarantee(false, "inline contiguous allocation not supported");
363 return NULL;
364 }
365
366 // Some heaps may be in an unparseable state at certain times between
367 // collections. This may be necessary for efficient implementation of
368 // certain allocation-related activities. Calling this function before
369 // attempting to parse a heap ensures that the heap is in a parsable
370 // state (provided other concurrent activity does not introduce
371 // unparsability). It is normally expected, therefore, that this
372 // method is invoked with the world stopped.
373 // NOTE: if you override this method, make sure you call
374 // super::ensure_parsability so that the non-generational
375 // part of the work gets done. See implementation of
376 // CollectedHeap::ensure_parsability and, for instance,
377 // that of GenCollectedHeap::ensure_parsability().
378 // The argument "retire_tlabs" controls whether existing TLABs
379 // are merely filled or also retired, thus preventing further
380 // allocation from them and necessitating allocation of new TLABs.
381 virtual void ensure_parsability(bool retire_tlabs);
382
383 // Section on thread-local allocation buffers (TLABs)
384 // If the heap supports thread-local allocation buffers, it should override
385 // the following methods:
386 // Returns "true" iff the heap supports thread-local allocation buffers.
387 // The default is "no".
388 virtual bool supports_tlab_allocation() const = 0;
389
390 // The amount of space available for thread-local allocation buffers.
391 virtual size_t tlab_capacity(Thread *thr) const = 0;
392
393 // The amount of used space for thread-local allocation buffers for the given thread.
394 virtual size_t tlab_used(Thread *thr) const = 0;
395
396 virtual size_t max_tlab_size() const;
397
398 // An estimate of the maximum allocation that could be performed
399 // for thread-local allocation buffers without triggering any
400 // collection or expansion activity.
401 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
402 guarantee(false, "thread-local allocation buffers not supported");
403 return 0;
404 }
405
406 // Can a compiler initialize a new object without store barriers?
407 // This permission only extends from the creation of a new object
408 // via a TLAB up to the first subsequent safepoint. If such permission
409 // is granted for this heap type, the compiler promises to call
410 // defer_store_barrier() below on any slow path allocation of
411 // a new object for which such initializing store barriers will
412 // have been elided.
413 virtual bool can_elide_tlab_store_barriers() const = 0;
414
415 // If a compiler is eliding store barriers for TLAB-allocated objects,
416 // there is probably a corresponding slow path which can produce
417 // an object allocated anywhere. The compiler's runtime support
418 // promises to call this function on such a slow-path-allocated
419 // object before performing initializations that have elided
420 // store barriers. Returns new_obj, or maybe a safer copy thereof.
421 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
422
423 // Answers whether an initializing store to a new object currently
424 // allocated at the given address doesn't need a store
425 // barrier. Returns "true" if it doesn't need an initializing
426 // store barrier; answers "false" if it does.
427 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
428
429 // If a compiler is eliding store barriers for TLAB-allocated objects,
430 // we will be informed of a slow-path allocation by a call
431 // to new_store_pre_barrier() above. Such a call precedes the
432 // initialization of the object itself, and no post-store-barriers will
433 // be issued. Some heap types require that the barrier strictly follows
434 // the initializing stores. (This is currently implemented by deferring the
435 // barrier until the next slow-path allocation or gc-related safepoint.)
436 // This interface answers whether a particular heap type needs the card
437 // mark to be thus strictly sequenced after the stores.
438 virtual bool card_mark_must_follow_store() const = 0;
439
440 // If the CollectedHeap was asked to defer a store barrier above,
441 // this informs it to flush such a deferred store barrier to the
442 // remembered set.
443 virtual void flush_deferred_store_barrier(JavaThread* thread);
444
445 // Perform a collection of the heap; intended for use in implementing
446 // "System.gc". This probably implies as full a collection as the
447 // "CollectedHeap" supports.
448 virtual void collect(GCCause::Cause cause) = 0;
449
450 // Perform a full collection
451 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
452
453 // This interface assumes that it's being called by the
454 // vm thread. It collects the heap assuming that the
455 // heap lock is already held and that we are executing in
456 // the context of the vm thread.
457 virtual void collect_as_vm_thread(GCCause::Cause cause);
458
459 // Returns the barrier set for this heap
460 BarrierSet* barrier_set() { return _barrier_set; }
461 void set_barrier_set(BarrierSet* barrier_set);
462
463 // Returns "true" iff there is a stop-world GC in progress. (I assume
464 // that it should answer "false" for the concurrent part of a concurrent
465 // collector -- dld).
466 bool is_gc_active() const { return _is_gc_active; }
467
468 // Total number of GC collections (started)
469 unsigned int total_collections() const { return _total_collections; }
470 unsigned int total_full_collections() const { return _total_full_collections;}
471
472 // Increment total number of GC collections (started)
473 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
474 void increment_total_collections(bool full = false) {
475 _total_collections++;
476 if (full) {
477 increment_total_full_collections();
478 }
479 }
480
481 void increment_total_full_collections() { _total_full_collections++; }
482
483 // Return the CollectorPolicy for the heap
484 virtual CollectorPolicy* collector_policy() const = 0;
485
486 // Iterate over all objects, calling "cl.do_object" on each.
487 virtual void object_iterate(ObjectClosure* cl) = 0;
488
489 // Similar to object_iterate() except iterates only
490 // over live objects.
491 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
492
493 // NOTE! There is no requirement that a collector implement these
494 // functions.
495 //
496 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
497 // each address in the (reserved) heap is a member of exactly
498 // one block. The defining characteristic of a block is that it is
499 // possible to find its size, and thus to progress forward to the next
500 // block. (Blocks may be of different sizes.) Thus, blocks may
501 // represent Java objects, or they might be free blocks in a
502 // free-list-based heap (or subheap), as long as the two kinds are
503 // distinguishable and the size of each is determinable.
504
505 // Returns the address of the start of the "block" that contains the
506 // address "addr". We say "blocks" instead of "object" since some heaps
507 // may not pack objects densely; a chunk may either be an object or a
508 // non-object.
509 virtual HeapWord* block_start(const void* addr) const = 0;
510
511 // Requires "addr" to be the start of a chunk, and returns its size.
512 // "addr + size" is required to be the start of a new chunk, or the end
513 // of the active area of the heap.
514 virtual size_t block_size(const HeapWord* addr) const = 0;
515
516 // Requires "addr" to be the start of a block, and returns "TRUE" iff
517 // the block is an object.
518 virtual bool block_is_obj(const HeapWord* addr) const = 0;
519
520 // Returns the longest time (in ms) that has elapsed since the last
521 // time that any part of the heap was examined by a garbage collection.
522 virtual jlong millis_since_last_gc() = 0;
523
524 // Perform any cleanup actions necessary before allowing a verification.
525 virtual void prepare_for_verify() = 0;
526
527 // Generate any dumps preceding or following a full gc
528 private:
529 void full_gc_dump(GCTimer* timer, bool before);
530 public:
531 void pre_full_gc_dump(GCTimer* timer);
532 void post_full_gc_dump(GCTimer* timer);
533
534 VirtualSpaceSummary create_heap_space_summary();
535 GCHeapSummary create_heap_summary();
536
537 MetaspaceSummary create_metaspace_summary();
538
539 // Print heap information on the given outputStream.
540 virtual void print_on(outputStream* st) const = 0;
541 // The default behavior is to call print_on() on tty.
542 virtual void print() const {
543 print_on(tty);
544 }
545 // Print more detailed heap information on the given
546 // outputStream. The default behavior is to call print_on(). It is
547 // up to each subclass to override it and add any additional output
548 // it needs.
549 virtual void print_extended_on(outputStream* st) const {
550 print_on(st);
551 }
552
553 virtual void print_on_error(outputStream* st) const;
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 // The default behavior is to call print_gc_threads_on() on tty.
559 void print_gc_threads() {
560 print_gc_threads_on(tty);
561 }
562 // Iterator for all GC threads (other than VM thread)
563 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
564
565 // Print any relevant tracing info that flags imply.
566 // Default implementation does nothing.
567 virtual void print_tracing_info() const = 0;
568
569 void print_heap_before_gc();
570 void print_heap_after_gc();
571
572 // Registering and unregistering an nmethod (compiled code) with the heap.
573 // Override with specific mechanism for each specialized heap type.
574 virtual void register_nmethod(nmethod* nm);
575 virtual void unregister_nmethod(nmethod* nm);
576
577 void trace_heap_before_gc(const GCTracer* gc_tracer);
578 void trace_heap_after_gc(const GCTracer* gc_tracer);
579
580 // Heap verification
581 virtual void verify(VerifyOption option) = 0;
582
583 // Return true if concurrent phase control (via
584 // request_concurrent_phase_control) is supported by this collector.
585 // The default implementation returns false.
586 virtual bool supports_concurrent_phase_control() const;
587
588 // Return a NULL terminated array of concurrent phase names provided
589 // by this collector. Supports Whitebox testing. These are the
590 // names recognized by request_concurrent_phase(). The default
591 // implementation returns an array of one NULL element.
592 virtual const char* const* concurrent_phases() const;
593
594 // Request the collector enter the indicated concurrent phase, and
595 // wait until it does so. Supports WhiteBox testing. Only one
596 // request may be active at a time. Phases are designated by name;
597 // the set of names and their meaning is GC-specific. Once the
598 // requested phase has been reached, the collector will attempt to
599 // avoid transitioning to a new phase until a new request is made.
600 // [Note: A collector might not be able to remain in a given phase.
601 // For example, a full collection might cancel an in-progress
602 // concurrent collection.]
603 //
604 // Returns true when the phase is reached. Returns false for an
605 // unknown phase. The default implementation returns false.
606 virtual bool request_concurrent_phase(const char* phase);
607
608 // Non product verification and debugging.
609 #ifndef PRODUCT
610 // Support for PromotionFailureALot. Return true if it's time to cause a
611 // promotion failure. The no-argument version uses
612 // this->_promotion_failure_alot_count as the counter.
613 inline bool promotion_should_fail(volatile size_t* count);
614 inline bool promotion_should_fail();
615
616 // Reset the PromotionFailureALot counters. Should be called at the end of a
617 // GC in which promotion failure occurred.
618 inline void reset_promotion_should_fail(volatile size_t* count);
619 inline void reset_promotion_should_fail();
620 #endif // #ifndef PRODUCT
621
622 #ifdef ASSERT
623 static int fired_fake_oom() {
624 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
625 }
626 #endif
627
628 public:
629 // Copy the current allocation context statistics for the specified contexts.
630 // For each context in contexts, set the corresponding entries in the totals
631 // and accuracy arrays to the current values held by the statistics. Each
632 // array should be of length len.
633 // Returns true if there are more stats available.
634 virtual bool copy_allocation_context_stats(const jint* contexts,
635 jlong* totals,
636 jbyte* accuracy,
637 jint len) {
638 return false;
639 }
640
641 };
642
643 // Class to set and reset the GC cause for a CollectedHeap.
644
645 class GCCauseSetter : StackObj {
646 CollectedHeap* _heap;
647 GCCause::Cause _previous_cause;
648 public:
649 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
650 assert(SafepointSynchronize::is_at_safepoint(),
651 "This method manipulates heap state without locking");
652 _heap = heap;
653 _previous_cause = _heap->gc_cause();
654 _heap->set_gc_cause(cause);
655 }
656
657 ~GCCauseSetter() {
658 assert(SafepointSynchronize::is_at_safepoint(),
659 "This method manipulates heap state without locking");
660 _heap->set_gc_cause(_previous_cause);
661 }
662 };
663
664 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP