1 /*
2 * Copyright (c) 2001, 2013, 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.
18 *
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_INTERFACE_COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP
27
28 #include "gc_interface/gcCause.hpp"
29 #include "gc_implementation/shared/gcWhen.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/barrierSet.hpp"
32 #include "runtime/handles.hpp"
33 #include "runtime/perfData.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "utilities/events.hpp"
36
37 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
38 // is an abstract class: there may be many different kinds of heaps. This
39 // class defines the functions that a heap must implement, and contains
40 // infrastructure common to all heaps.
41
42 class AdaptiveSizePolicy;
43 class BarrierSet;
44 class CollectorPolicy;
45 class GCHeapSummary;
46 class GCTimer;
47 class GCTracer;
48 class MetaspaceSummary;
49 class Thread;
50 class ThreadClosure;
51 class VirtualSpaceSummary;
52
53 class GCMessage : public FormatBuffer<1024> {
54 public:
55 bool is_before;
56
57 public:
58 GCMessage() {}
59 };
60
61 class GCHeapLog : public EventLogBase<GCMessage> {
62 private:
63 void log_heap(bool before);
64
65 public:
66 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
67
68 void log_heap_before() {
69 log_heap(true);
70 }
71 void log_heap_after() {
72 log_heap(false);
73 }
74 };
75
76 //
77 // CollectedHeap
78 // SharedHeap
79 // GenCollectedHeap
80 // G1CollectedHeap
81 // ParallelScavengeHeap
82 //
83 class CollectedHeap : public CHeapObj<mtInternal> {
84 friend class VMStructs;
85 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
86
87 #ifdef ASSERT
88 static int _fire_out_of_memory_count;
89 #endif
90
91 // Used for filler objects (static, but initialized in ctor).
92 static size_t _filler_array_max_size;
93
94 GCHeapLog* _gc_heap_log;
95
96 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used
97 bool _defer_initial_card_mark;
98
99 protected:
100 MemRegion _reserved;
101 BarrierSet* _barrier_set;
102 bool _is_gc_active;
103 uint _n_par_threads;
104
105 unsigned int _total_collections; // ... started
106 unsigned int _total_full_collections; // ... started
107 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
108 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
109
110 // Reason for current garbage collection. Should be set to
111 // a value reflecting no collection between collections.
112 GCCause::Cause _gc_cause;
113 GCCause::Cause _gc_lastcause;
114 PerfStringVariable* _perf_gc_cause;
115 PerfStringVariable* _perf_gc_lastcause;
116
117 // Constructor
118 CollectedHeap();
119
120 // Do common initializations that must follow instance construction,
121 // for example, those needing virtual calls.
122 // This code could perhaps be moved into initialize() but would
123 // be slightly more awkward because we want the latter to be a
124 // pure virtual.
125 void pre_initialize();
126
127 // Create a new tlab. All TLAB allocations must go through this.
128 virtual HeapWord* allocate_new_tlab(size_t size);
129
130 // Accumulate statistics on all tlabs.
131 virtual void accumulate_statistics_all_tlabs();
132
133 // Reinitialize tlabs before resuming mutators.
134 virtual void resize_all_tlabs();
135
136 // Allocate from the current thread's TLAB, with broken-out slow path.
137 inline static HeapWord* allocate_from_tlab(KlassHandle klass, Thread* thread, size_t size);
138 static HeapWord* allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size);
139
140 // Allocate an uninitialized block of the given size, or returns NULL if
141 // this is impossible.
142 inline static HeapWord* common_mem_allocate_noinit(KlassHandle klass, size_t size, TRAPS);
143
144 // Like allocate_init, but the block returned by a successful allocation
145 // is guaranteed initialized to zeros.
146 inline static HeapWord* common_mem_allocate_init(KlassHandle klass, size_t size, TRAPS);
147
148 // Helper functions for (VM) allocation.
149 inline static void post_allocation_setup_common(KlassHandle klass, HeapWord* obj);
150 inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
151 HeapWord* objPtr);
152
153 inline static void post_allocation_setup_obj(KlassHandle klass, HeapWord* obj);
154
155 inline static void post_allocation_setup_array(KlassHandle klass,
156 HeapWord* obj, int length);
157
158 // Clears an allocated object.
159 inline static void init_obj(HeapWord* obj, size_t size);
160
161 // Filler object utilities.
162 static inline size_t filler_array_hdr_size();
163 static inline size_t filler_array_min_size();
164
165 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
166 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
167
168 // Fill with a single array; caller must ensure filler_array_min_size() <=
169 // words <= filler_array_max_size().
170 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
171
172 // Fill with a single object (either an int array or a java.lang.Object).
173 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
174
175 virtual void trace_heap(GCWhen::Type when, GCTracer* tracer);
176
177 // Verification functions
178 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
179 PRODUCT_RETURN;
180 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
181 PRODUCT_RETURN;
182 debug_only(static void check_for_valid_allocation_state();)
183
184 public:
185 enum Name {
186 Abstract,
187 SharedHeap,
188 GenCollectedHeap,
189 ParallelScavengeHeap,
190 G1CollectedHeap
191 };
192
193 static inline size_t filler_array_max_size() {
194 return _filler_array_max_size;
195 }
196
197 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
198
199 /**
200 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
201 * and JNI_OK on success.
202 */
203 virtual jint initialize() = 0;
204
205 // In many heaps, there will be a need to perform some initialization activities
206 // after the Universe is fully formed, but before general heap allocation is allowed.
207 // This is the correct place to place such initialization methods.
208 virtual void post_initialize() = 0;
209
210 MemRegion reserved_region() const { return _reserved; }
211 address base() const { return (address)reserved_region().start(); }
212
213 virtual size_t capacity() const = 0;
214 virtual size_t used() const = 0;
215
216 // Return "true" if the part of the heap that allocates Java
217 // objects has reached the maximal committed limit that it can
218 // reach, without a garbage collection.
219 virtual bool is_maximal_no_gc() const = 0;
220
221 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
222 // memory that the vm could make available for storing 'normal' java objects.
223 // This is based on the reserved address space, but should not include space
224 // that the vm uses internally for bookkeeping or temporary storage
225 // (e.g., in the case of the young gen, one of the survivor
226 // spaces).
227 virtual size_t max_capacity() const = 0;
228
229 // Returns "TRUE" if "p" points into the reserved area of the heap.
230 bool is_in_reserved(const void* p) const {
231 return _reserved.contains(p);
232 }
233
234 bool is_in_reserved_or_null(const void* p) const {
235 return p == NULL || is_in_reserved(p);
236 }
237
238 // Returns "TRUE" iff "p" points into the committed areas of the heap.
239 // Since this method can be expensive in general, we restrict its
240 // use to assertion checking only.
241 virtual bool is_in(const void* p) const = 0;
242
243 bool is_in_or_null(const void* p) const {
244 return p == NULL || is_in(p);
245 }
246
247 bool is_in_place(Metadata** p) {
248 return !Universe::heap()->is_in(p);
249 }
250 bool is_in_place(oop* p) { return Universe::heap()->is_in(p); }
251 bool is_in_place(narrowOop* p) {
252 oop o = oopDesc::load_decode_heap_oop_not_null(p);
253 return Universe::heap()->is_in((const void*)o);
254 }
255
256 // Let's define some terms: a "closed" subset of a heap is one that
257 //
258 // 1) contains all currently-allocated objects, and
259 //
260 // 2) is closed under reference: no object in the closed subset
261 // references one outside the closed subset.
262 //
263 // Membership in a heap's closed subset is useful for assertions.
264 // Clearly, the entire heap is a closed subset, so the default
265 // implementation is to use "is_in_reserved". But this may not be too
266 // liberal to perform useful checking. Also, the "is_in" predicate
267 // defines a closed subset, but may be too expensive, since "is_in"
268 // verifies that its argument points to an object head. The
269 // "closed_subset" method allows a heap to define an intermediate
270 // predicate, allowing more precise checking than "is_in_reserved" at
271 // lower cost than "is_in."
272
273 // One important case is a heap composed of disjoint contiguous spaces,
274 // such as the Garbage-First collector. Such heaps have a convenient
275 // closed subset consisting of the allocated portions of those
276 // contiguous spaces.
277
278 // Return "TRUE" iff the given pointer points into the heap's defined
279 // closed subset (which defaults to the entire heap).
280 virtual bool is_in_closed_subset(const void* p) const {
281 return is_in_reserved(p);
282 }
283
284 bool is_in_closed_subset_or_null(const void* p) const {
285 return p == NULL || is_in_closed_subset(p);
286 }
287
288 #ifdef ASSERT
289 // Returns true if "p" is in the part of the
290 // heap being collected.
291 virtual bool is_in_partial_collection(const void *p) = 0;
292 #endif
293
294 // An object is scavengable if its location may move during a scavenge.
295 // (A scavenge is a GC which is not a full GC.)
296 virtual bool is_scavengable(const void *p) = 0;
297
298 void set_gc_cause(GCCause::Cause v) {
299 if (UsePerfData) {
300 _gc_lastcause = _gc_cause;
301 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
302 _perf_gc_cause->set_value(GCCause::to_string(v));
303 }
304 _gc_cause = v;
305 }
306 GCCause::Cause gc_cause() { return _gc_cause; }
307
308 // Number of threads currently working on GC tasks.
309 uint n_par_threads() { return _n_par_threads; }
310
311 // May be overridden to set additional parallelism.
312 virtual void set_par_threads(uint t) { _n_par_threads = t; };
313
314 // Allocate and initialize instances of Class
315 static oop Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS);
316
317 // General obj/array allocation facilities.
318 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
319 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
320 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS);
321
322 inline static void post_allocation_install_obj_klass(KlassHandle klass,
323 oop obj);
324
325 // Raw memory allocation facilities
326 // The obj and array allocate methods are covers for these methods.
327 // mem_allocate() should never be
328 // called to allocate TLABs, only individual objects.
329 virtual HeapWord* mem_allocate(size_t size,
330 bool* gc_overhead_limit_was_exceeded) = 0;
331
332 // Utilities for turning raw memory into filler objects.
333 //
334 // min_fill_size() is the smallest region that can be filled.
335 // fill_with_objects() can fill arbitrary-sized regions of the heap using
336 // multiple objects. fill_with_object() is for regions known to be smaller
337 // than the largest array of integers; it uses a single object to fill the
338 // region and has slightly less overhead.
339 static size_t min_fill_size() {
340 return size_t(align_object_size(oopDesc::header_size()));
341 }
342
343 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
344
345 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
346 static void fill_with_object(MemRegion region, bool zap = true) {
347 fill_with_object(region.start(), region.word_size(), zap);
348 }
349 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
350 fill_with_object(start, pointer_delta(end, start), zap);
351 }
352
353 // Some heaps may offer a contiguous region for shared non-blocking
354 // allocation, via inlined code (by exporting the address of the top and
355 // end fields defining the extent of the contiguous allocation region.)
356
357 // This function returns "true" iff the heap supports this kind of
358 // allocation. (Default is "no".)
359 virtual bool supports_inline_contig_alloc() const {
360 return false;
361 }
362 // These functions return the addresses of the fields that define the
363 // boundaries of the contiguous allocation area. (These fields should be
364 // physically near to one another.)
365 virtual HeapWord** top_addr() const {
366 guarantee(false, "inline contiguous allocation not supported");
367 return NULL;
368 }
369 virtual HeapWord** end_addr() const {
370 guarantee(false, "inline contiguous allocation not supported");
371 return NULL;
372 }
373
374 // Some heaps may be in an unparseable state at certain times between
375 // collections. This may be necessary for efficient implementation of
376 // certain allocation-related activities. Calling this function before
377 // attempting to parse a heap ensures that the heap is in a parsable
378 // state (provided other concurrent activity does not introduce
379 // unparsability). It is normally expected, therefore, that this
380 // method is invoked with the world stopped.
381 // NOTE: if you override this method, make sure you call
382 // super::ensure_parsability so that the non-generational
383 // part of the work gets done. See implementation of
384 // CollectedHeap::ensure_parsability and, for instance,
385 // that of GenCollectedHeap::ensure_parsability().
386 // The argument "retire_tlabs" controls whether existing TLABs
387 // are merely filled or also retired, thus preventing further
388 // allocation from them and necessitating allocation of new TLABs.
389 virtual void ensure_parsability(bool retire_tlabs);
390
391 // Return an estimate of the maximum allocation that could be performed
392 // without triggering any collection or expansion activity. In a
393 // generational collector, for example, this is probably the largest
394 // allocation that could be supported (without expansion) in the youngest
395 // generation. It is "unsafe" because no locks are taken; the result
396 // should be treated as an approximation, not a guarantee, for use in
397 // heuristic resizing decisions.
398 virtual size_t unsafe_max_alloc() = 0;
399
400 // Section on thread-local allocation buffers (TLABs)
401 // If the heap supports thread-local allocation buffers, it should override
402 // the following methods:
403 // Returns "true" iff the heap supports thread-local allocation buffers.
404 // The default is "no".
405 virtual bool supports_tlab_allocation() const {
406 return false;
407 }
408 // The amount of space available for thread-local allocation buffers.
409 virtual size_t tlab_capacity(Thread *thr) const {
410 guarantee(false, "thread-local allocation buffers not supported");
411 return 0;
412 }
413 // An estimate of the maximum allocation that could be performed
414 // for thread-local allocation buffers without triggering any
415 // collection or expansion activity.
416 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
417 guarantee(false, "thread-local allocation buffers not supported");
418 return 0;
419 }
420
421 // Can a compiler initialize a new object without store barriers?
422 // This permission only extends from the creation of a new object
423 // via a TLAB up to the first subsequent safepoint. If such permission
424 // is granted for this heap type, the compiler promises to call
425 // defer_store_barrier() below on any slow path allocation of
426 // a new object for which such initializing store barriers will
427 // have been elided.
428 virtual bool can_elide_tlab_store_barriers() const = 0;
429
430 // If a compiler is eliding store barriers for TLAB-allocated objects,
431 // there is probably a corresponding slow path which can produce
432 // an object allocated anywhere. The compiler's runtime support
433 // promises to call this function on such a slow-path-allocated
434 // object before performing initializations that have elided
435 // store barriers. Returns new_obj, or maybe a safer copy thereof.
436 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
437
438 // Answers whether an initializing store to a new object currently
439 // allocated at the given address doesn't need a store
440 // barrier. Returns "true" if it doesn't need an initializing
441 // store barrier; answers "false" if it does.
442 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
443
444 // If a compiler is eliding store barriers for TLAB-allocated objects,
445 // we will be informed of a slow-path allocation by a call
446 // to new_store_pre_barrier() above. Such a call precedes the
447 // initialization of the object itself, and no post-store-barriers will
448 // be issued. Some heap types require that the barrier strictly follows
449 // the initializing stores. (This is currently implemented by deferring the
450 // barrier until the next slow-path allocation or gc-related safepoint.)
451 // This interface answers whether a particular heap type needs the card
452 // mark to be thus strictly sequenced after the stores.
453 virtual bool card_mark_must_follow_store() const = 0;
454
455 // If the CollectedHeap was asked to defer a store barrier above,
456 // this informs it to flush such a deferred store barrier to the
457 // remembered set.
458 virtual void flush_deferred_store_barrier(JavaThread* thread);
459
460 // Does this heap support heap inspection (+PrintClassHistogram?)
461 virtual bool supports_heap_inspection() const = 0;
462
463 // Perform a collection of the heap; intended for use in implementing
464 // "System.gc". This probably implies as full a collection as the
465 // "CollectedHeap" supports.
466 virtual void collect(GCCause::Cause cause) = 0;
467
468 // Perform a full collection
469 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
470
471 // This interface assumes that it's being called by the
472 // vm thread. It collects the heap assuming that the
473 // heap lock is already held and that we are executing in
474 // the context of the vm thread.
475 virtual void collect_as_vm_thread(GCCause::Cause cause);
476
477 virtual void inform_non_gc_safepoint() {}
478
479 // Callback from VM_CollectForMetadataAllocation operation.
480 MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
481 size_t size,
482 Metaspace::MetadataType mdtype);
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 void oop_iterate_no_header(OopClosure* cl);
514
515 // Iterate over all the ref-containing fields of all objects, calling
516 // "cl.do_oop" on each.
517 virtual void oop_iterate(ExtendedOopClosure* cl) = 0;
518
519 // Iterate over all objects, calling "cl.do_object" on each.
520 virtual void object_iterate(ObjectClosure* cl) = 0;
521
522 // Similar to object_iterate() except iterates only
523 // over live objects.
524 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
525
526 // NOTE! There is no requirement that a collector implement these
527 // functions.
528 //
529 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
530 // each address in the (reserved) heap is a member of exactly
531 // one block. The defining characteristic of a block is that it is
532 // possible to find its size, and thus to progress forward to the next
533 // block. (Blocks may be of different sizes.) Thus, blocks may
534 // represent Java objects, or they might be free blocks in a
535 // free-list-based heap (or subheap), as long as the two kinds are
536 // distinguishable and the size of each is determinable.
537
538 // Returns the address of the start of the "block" that contains the
539 // address "addr". We say "blocks" instead of "object" since some heaps
540 // may not pack objects densely; a chunk may either be an object or a
541 // non-object.
542 virtual HeapWord* block_start(const void* addr) const = 0;
543
544 // Requires "addr" to be the start of a chunk, and returns its size.
545 // "addr + size" is required to be the start of a new chunk, or the end
546 // of the active area of the heap.
547 virtual size_t block_size(const HeapWord* addr) const = 0;
548
549 // Requires "addr" to be the start of a block, and returns "TRUE" iff
550 // the block is an object.
551 virtual bool block_is_obj(const HeapWord* addr) const = 0;
552
553 // Returns the longest time (in ms) that has elapsed since the last
554 // time that any part of the heap was examined by a garbage collection.
555 virtual jlong millis_since_last_gc() = 0;
556
557 // Perform any cleanup actions necessary before allowing a verification.
558 virtual void prepare_for_verify() = 0;
559
560 // Generate any dumps preceding or following a full gc
561 void pre_full_gc_dump(GCTimer* timer);
562 void post_full_gc_dump(GCTimer* timer);
563
564 VirtualSpaceSummary create_heap_space_summary();
565 GCHeapSummary create_heap_summary();
566
567 MetaspaceSummary create_metaspace_summary();
568
569 // Print heap information on the given outputStream.
570 virtual void print_on(outputStream* st) const = 0;
571 // The default behavior is to call print_on() on tty.
572 virtual void print() const {
573 print_on(tty);
574 }
575 // Print more detailed heap information on the given
576 // outputStream. The default behavior is to call print_on(). It is
577 // up to each subclass to override it and add any additional output
578 // it needs.
579 virtual void print_extended_on(outputStream* st) const {
580 print_on(st);
581 }
582
583 virtual void print_on_error(outputStream* st) const {
584 st->print_cr("Heap:");
585 print_extended_on(st);
586 st->cr();
587
588 _barrier_set->print_on(st);
589 }
590
591 // Print all GC threads (other than the VM thread)
592 // used by this heap.
593 virtual void print_gc_threads_on(outputStream* st) const = 0;
594 // The default behavior is to call print_gc_threads_on() on tty.
595 void print_gc_threads() {
596 print_gc_threads_on(tty);
597 }
598 // Iterator for all GC threads (other than VM thread)
599 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
600
601 // Print any relevant tracing info that flags imply.
602 // Default implementation does nothing.
603 virtual void print_tracing_info() const = 0;
604
605 void print_heap_before_gc();
606 void print_heap_after_gc();
607
608 void trace_heap_before_gc(GCTracer* gc_tracer);
609 void trace_heap_after_gc(GCTracer* gc_tracer);
610
611 // Heap verification
612 virtual void verify(bool silent, VerifyOption option) = 0;
613
614 // Non product verification and debugging.
615 #ifndef PRODUCT
616 // Support for PromotionFailureALot. Return true if it's time to cause a
617 // promotion failure. The no-argument version uses
618 // this->_promotion_failure_alot_count as the counter.
619 inline bool promotion_should_fail(volatile size_t* count);
620 inline bool promotion_should_fail();
621
622 // Reset the PromotionFailureALot counters. Should be called at the end of a
623 // GC in which promotion failure occurred.
624 inline void reset_promotion_should_fail(volatile size_t* count);
625 inline void reset_promotion_should_fail();
626 #endif // #ifndef PRODUCT
627
628 #ifdef ASSERT
629 static int fired_fake_oom() {
630 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
631 }
632 #endif
633
634 public:
635 // This is a convenience method that is used in cases where
636 // the actual number of GC worker threads is not pertinent but
637 // only whether there more than 0. Use of this method helps
638 // reduce the occurrence of ParallelGCThreads to uses where the
639 // actual number may be germane.
640 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; }
641
642 /////////////// Unit tests ///////////////
643
644 NOT_PRODUCT(static void test_is_in();)
645 };
646
647 // Class to set and reset the GC cause for a CollectedHeap.
648
649 class GCCauseSetter : StackObj {
650 CollectedHeap* _heap;
651 GCCause::Cause _previous_cause;
652 public:
653 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
654 assert(SafepointSynchronize::is_at_safepoint(),
655 "This method manipulates heap state without locking");
656 _heap = heap;
657 _previous_cause = _heap->gc_cause();
658 _heap->set_gc_cause(cause);
659 }
660
661 ~GCCauseSetter() {
662 assert(SafepointSynchronize::is_at_safepoint(),
663 "This method manipulates heap state without locking");
664 _heap->set_gc_cause(_previous_cause);
665 }
666 };
667
668 class NonGCSafepointMark : StackObj {
669 CollectedHeap* _heap;
670 unsigned int _total_collections;
671 unsigned int _total_full_collections;
672 public:
673 NonGCSafepointMark(CollectedHeap* heap) : _heap(heap),
674 _total_collections(heap->total_collections()),
675 _total_full_collections(heap->total_full_collections()) { }
676
677 ~NonGCSafepointMark() {
678 if (_heap->total_collections() == _total_collections &&
679 _heap->total_full_collections() == _total_full_collections) {
680 _heap->inform_non_gc_safepoint();
681 }
682 }
683 };
684
685 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP