1 /*
2 * Copyright (c) 2001, 2014, 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 class nmethod;
53
54 class GCMessage : public FormatBuffer<1024> {
55 public:
56 bool is_before;
57
58 public:
59 GCMessage() {}
60 };
61
62 class GCHeapLog : public EventLogBase<GCMessage> {
63 private:
64 void log_heap(bool before);
65
66 public:
67 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
68
69 void log_heap_before() {
70 log_heap(true);
71 }
72 void log_heap_after() {
73 log_heap(false);
74 }
75 };
76
77 //
78 // CollectedHeap
79 // SharedHeap
80 // GenCollectedHeap
81 // G1CollectedHeap
82 // ParallelScavengeHeap
83 //
84 class CollectedHeap : public CHeapObj<mtInternal> {
85 friend class VMStructs;
86 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
87
88 #ifdef ASSERT
89 static int _fire_out_of_memory_count;
90 #endif
91
92 // Used for filler objects (static, but initialized in ctor).
93 static size_t _filler_array_max_size;
94
95 GCHeapLog* _gc_heap_log;
96
97 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used
98 bool _defer_initial_card_mark;
99
100 protected:
101 MemRegion _reserved;
102 BarrierSet* _barrier_set;
103 bool _is_gc_active;
104 uint _n_par_threads;
105
106 unsigned int _total_collections; // ... started
107 unsigned int _total_full_collections; // ... started
108 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
109 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
110
111 // Reason for current garbage collection. Should be set to
112 // a value reflecting no collection between collections.
113 GCCause::Cause _gc_cause;
114 GCCause::Cause _gc_lastcause;
115 PerfStringVariable* _perf_gc_cause;
116 PerfStringVariable* _perf_gc_lastcause;
117
118 // Constructor
119 CollectedHeap();
120
121 // Do common initializations that must follow instance construction,
122 // for example, those needing virtual calls.
123 // This code could perhaps be moved into initialize() but would
124 // be slightly more awkward because we want the latter to be a
125 // pure virtual.
126 void pre_initialize();
127
128 // Create a new tlab. All TLAB allocations must go through this.
129 virtual HeapWord* allocate_new_tlab(size_t size);
130
131 // Accumulate statistics on all tlabs.
132 virtual void accumulate_statistics_all_tlabs();
133
134 // Reinitialize tlabs before resuming mutators.
135 virtual void resize_all_tlabs();
136
137 // Allocate from the current thread's TLAB, with broken-out slow path.
138 inline static HeapWord* allocate_from_tlab(KlassHandle klass, Thread* thread, size_t size);
139 static HeapWord* allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size);
140
141 // Allocate an uninitialized block of the given size, or returns NULL if
142 // this is impossible.
143 inline static HeapWord* common_mem_allocate_noinit(KlassHandle klass, size_t size, TRAPS);
144
145 // Like allocate_init, but the block returned by a successful allocation
146 // is guaranteed initialized to zeros.
147 inline static HeapWord* common_mem_allocate_init(KlassHandle klass, size_t size, TRAPS);
148
149 // Helper functions for (VM) allocation.
150 inline static void post_allocation_setup_common(KlassHandle klass, HeapWord* obj);
151 inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
152 HeapWord* objPtr);
153
154 inline static void post_allocation_setup_obj(KlassHandle klass, HeapWord* obj, int size);
155
156 inline static void post_allocation_setup_array(KlassHandle klass,
157 HeapWord* obj, int length);
158
159 // Clears an allocated object.
160 inline static void init_obj(HeapWord* obj, size_t size);
161
162 // Filler object utilities.
163 static inline size_t filler_array_hdr_size();
164 static inline size_t filler_array_min_size();
165
166 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
167 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
168
169 // Fill with a single array; caller must ensure filler_array_min_size() <=
170 // words <= filler_array_max_size().
171 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
172
173 // Fill with a single object (either an int array or a java.lang.Object).
174 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
175
176 virtual void trace_heap(GCWhen::Type when, GCTracer* tracer);
177
178 // Verification functions
179 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
180 PRODUCT_RETURN;
181 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
182 PRODUCT_RETURN;
183 debug_only(static void check_for_valid_allocation_state();)
184
185 public:
186 enum Name {
187 Abstract,
188 SharedHeap,
189 GenCollectedHeap,
190 ParallelScavengeHeap,
191 G1CollectedHeap,
192 EpsilonCollectedHeap,
193 };
194
195 static inline size_t filler_array_max_size() {
196 return _filler_array_max_size;
197 }
198
199 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
200
201 /**
202 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
203 * and JNI_OK on success.
204 */
205 virtual jint initialize() = 0;
206
207 // In many heaps, there will be a need to perform some initialization activities
208 // after the Universe is fully formed, but before general heap allocation is allowed.
209 // This is the correct place to place such initialization methods.
210 virtual void post_initialize() = 0;
211
212 // Stop any onging concurrent work and prepare for exit.
213 virtual void stop() {}
214
215 MemRegion reserved_region() const { return _reserved; }
216 address base() const { return (address)reserved_region().start(); }
217
218 virtual size_t capacity() const = 0;
219 virtual size_t used() const = 0;
220
221 // Return "true" if the part of the heap that allocates Java
222 // objects has reached the maximal committed limit that it can
223 // reach, without a garbage collection.
224 virtual bool is_maximal_no_gc() const = 0;
225
226 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
227 // memory that the vm could make available for storing 'normal' java objects.
228 // This is based on the reserved address space, but should not include space
229 // that the vm uses internally for bookkeeping or temporary storage
230 // (e.g., in the case of the young gen, one of the survivor
231 // spaces).
232 virtual size_t max_capacity() const = 0;
233
234 // Returns "TRUE" if "p" points into the reserved area of the heap.
235 bool is_in_reserved(const void* p) const {
236 return _reserved.contains(p);
237 }
238
239 bool is_in_reserved_or_null(const void* p) const {
240 return p == NULL || is_in_reserved(p);
241 }
242
243 // Returns "TRUE" iff "p" points into the committed areas of the heap.
244 // Since this method can be expensive in general, we restrict its
245 // use to assertion checking only.
246 virtual bool is_in(const void* p) const = 0;
247
248 bool is_in_or_null(const void* p) const {
249 return p == NULL || is_in(p);
250 }
251
252 bool is_in_place(Metadata** p) {
253 return !Universe::heap()->is_in(p);
254 }
255 bool is_in_place(oop* p) { return Universe::heap()->is_in(p); }
256 bool is_in_place(narrowOop* p) {
257 oop o = oopDesc::load_decode_heap_oop_not_null(p);
258 return Universe::heap()->is_in((const void*)o);
259 }
260
261 // Let's define some terms: a "closed" subset of a heap is one that
262 //
263 // 1) contains all currently-allocated objects, and
264 //
265 // 2) is closed under reference: no object in the closed subset
266 // references one outside the closed subset.
267 //
268 // Membership in a heap's closed subset is useful for assertions.
269 // Clearly, the entire heap is a closed subset, so the default
270 // implementation is to use "is_in_reserved". But this may not be too
271 // liberal to perform useful checking. Also, the "is_in" predicate
272 // defines a closed subset, but may be too expensive, since "is_in"
273 // verifies that its argument points to an object head. The
274 // "closed_subset" method allows a heap to define an intermediate
275 // predicate, allowing more precise checking than "is_in_reserved" at
276 // lower cost than "is_in."
277
278 // One important case is a heap composed of disjoint contiguous spaces,
279 // such as the Garbage-First collector. Such heaps have a convenient
280 // closed subset consisting of the allocated portions of those
281 // contiguous spaces.
282
283 // Return "TRUE" iff the given pointer points into the heap's defined
284 // closed subset (which defaults to the entire heap).
285 virtual bool is_in_closed_subset(const void* p) const {
286 return is_in_reserved(p);
287 }
288
289 bool is_in_closed_subset_or_null(const void* p) const {
290 return p == NULL || is_in_closed_subset(p);
291 }
292
293 #ifdef ASSERT
294 // Returns true if "p" is in the part of the
295 // heap being collected.
296 virtual bool is_in_partial_collection(const void *p) = 0;
297 #endif
298
299 // An object is scavengable if its location may move during a scavenge.
300 // (A scavenge is a GC which is not a full GC.)
301 virtual bool is_scavengable(const void *p) = 0;
302
303 void set_gc_cause(GCCause::Cause v) {
304 if (UsePerfData) {
305 _gc_lastcause = _gc_cause;
306 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
307 _perf_gc_cause->set_value(GCCause::to_string(v));
308 }
309 _gc_cause = v;
310 }
311 GCCause::Cause gc_cause() { return _gc_cause; }
312
313 // Number of threads currently working on GC tasks.
314 uint n_par_threads() { return _n_par_threads; }
315
316 // May be overridden to set additional parallelism.
317 virtual void set_par_threads(uint t) { _n_par_threads = t; };
318
319 // General obj/array allocation facilities.
320 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
321 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
322 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS);
323
324 inline static void post_allocation_install_obj_klass(KlassHandle klass,
325 oop obj);
326
327 // Raw memory allocation facilities
328 // The obj and array allocate methods are covers for these methods.
329 // mem_allocate() should never be
330 // called to allocate TLABs, only individual objects.
331 virtual HeapWord* mem_allocate(size_t size,
332 bool* gc_overhead_limit_was_exceeded) = 0;
333
334 // Utilities for turning raw memory into filler objects.
335 //
336 // min_fill_size() is the smallest region that can be filled.
337 // fill_with_objects() can fill arbitrary-sized regions of the heap using
338 // multiple objects. fill_with_object() is for regions known to be smaller
339 // than the largest array of integers; it uses a single object to fill the
340 // region and has slightly less overhead.
341 static size_t min_fill_size() {
342 return size_t(align_object_size(oopDesc::header_size()));
343 }
344
345 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
346
347 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
348 static void fill_with_object(MemRegion region, bool zap = true) {
349 fill_with_object(region.start(), region.word_size(), zap);
350 }
351 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
352 fill_with_object(start, pointer_delta(end, start), zap);
353 }
354
355 // Return the address "addr" aligned by "alignment_in_bytes" if such
356 // an address is below "end". Return NULL otherwise.
357 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
358 HeapWord* end,
359 unsigned short alignment_in_bytes);
360
361 // Some heaps may offer a contiguous region for shared non-blocking
362 // allocation, via inlined code (by exporting the address of the top and
363 // end fields defining the extent of the contiguous allocation region.)
364
365 // This function returns "true" iff the heap supports this kind of
366 // allocation. (Default is "no".)
367 virtual bool supports_inline_contig_alloc() const {
368 return false;
369 }
370 // These functions return the addresses of the fields that define the
371 // boundaries of the contiguous allocation area. (These fields should be
372 // physically near to one another.)
373 virtual HeapWord** top_addr() const {
374 guarantee(false, "inline contiguous allocation not supported");
375 return NULL;
376 }
377 virtual HeapWord** end_addr() const {
378 guarantee(false, "inline contiguous allocation not supported");
379 return NULL;
380 }
381
382 // Some heaps may be in an unparseable state at certain times between
383 // collections. This may be necessary for efficient implementation of
384 // certain allocation-related activities. Calling this function before
385 // attempting to parse a heap ensures that the heap is in a parsable
386 // state (provided other concurrent activity does not introduce
387 // unparsability). It is normally expected, therefore, that this
388 // method is invoked with the world stopped.
389 // NOTE: if you override this method, make sure you call
390 // super::ensure_parsability so that the non-generational
391 // part of the work gets done. See implementation of
392 // CollectedHeap::ensure_parsability and, for instance,
393 // that of GenCollectedHeap::ensure_parsability().
394 // The argument "retire_tlabs" controls whether existing TLABs
395 // are merely filled or also retired, thus preventing further
396 // allocation from them and necessitating allocation of new TLABs.
397 virtual void ensure_parsability(bool retire_tlabs);
398
399 // Section on thread-local allocation buffers (TLABs)
400 // If the heap supports thread-local allocation buffers, it should override
401 // the following methods:
402 // Returns "true" iff the heap supports thread-local allocation buffers.
403 // The default is "no".
404 virtual bool supports_tlab_allocation() const = 0;
405
406 // The amount of space available for thread-local allocation buffers.
407 virtual size_t tlab_capacity(Thread *thr) const = 0;
408
409 // The amount of used space for thread-local allocation buffers for the given thread.
410 virtual size_t tlab_used(Thread *thr) const = 0;
411
412 virtual size_t max_tlab_size() const;
413
414 // An estimate of the maximum allocation that could be performed
415 // for thread-local allocation buffers without triggering any
416 // collection or expansion activity.
417 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
418 guarantee(false, "thread-local allocation buffers not supported");
419 return 0;
420 }
421
422 // Can a compiler initialize a new object without store barriers?
423 // This permission only extends from the creation of a new object
424 // via a TLAB up to the first subsequent safepoint. If such permission
425 // is granted for this heap type, the compiler promises to call
426 // defer_store_barrier() below on any slow path allocation of
427 // a new object for which such initializing store barriers will
428 // have been elided.
429 virtual bool can_elide_tlab_store_barriers() const = 0;
430
431 // If a compiler is eliding store barriers for TLAB-allocated objects,
432 // there is probably a corresponding slow path which can produce
433 // an object allocated anywhere. The compiler's runtime support
434 // promises to call this function on such a slow-path-allocated
435 // object before performing initializations that have elided
436 // store barriers. Returns new_obj, or maybe a safer copy thereof.
437 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
438
439 // Answers whether an initializing store to a new object currently
440 // allocated at the given address doesn't need a store
441 // barrier. Returns "true" if it doesn't need an initializing
442 // store barrier; answers "false" if it does.
443 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
444
445 // If a compiler is eliding store barriers for TLAB-allocated objects,
446 // we will be informed of a slow-path allocation by a call
447 // to new_store_pre_barrier() above. Such a call precedes the
448 // initialization of the object itself, and no post-store-barriers will
449 // be issued. Some heap types require that the barrier strictly follows
450 // the initializing stores. (This is currently implemented by deferring the
451 // barrier until the next slow-path allocation or gc-related safepoint.)
452 // This interface answers whether a particular heap type needs the card
453 // mark to be thus strictly sequenced after the stores.
454 virtual bool card_mark_must_follow_store() const = 0;
455
456 // If the CollectedHeap was asked to defer a store barrier above,
457 // this informs it to flush such a deferred store barrier to the
458 // remembered set.
459 virtual void flush_deferred_store_barrier(JavaThread* thread);
460
461 // Does this heap support heap inspection (+PrintClassHistogram?)
462 virtual bool supports_heap_inspection() const = 0;
463
464 // Perform a collection of the heap; intended for use in implementing
465 // "System.gc". This probably implies as full a collection as the
466 // "CollectedHeap" supports.
467 virtual void collect(GCCause::Cause cause) = 0;
468
469 // Perform a full collection
470 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
471
472 // This interface assumes that it's being called by the
473 // vm thread. It collects the heap assuming that the
474 // heap lock is already held and that we are executing in
475 // the context of the vm thread.
476 virtual void collect_as_vm_thread(GCCause::Cause cause);
477
478 // Returns the barrier set for this heap
479 BarrierSet* barrier_set() { return _barrier_set; }
480
481 // Returns "true" iff there is a stop-world GC in progress. (I assume
482 // that it should answer "false" for the concurrent part of a concurrent
483 // collector -- dld).
484 bool is_gc_active() const { return _is_gc_active; }
485
486 // Total number of GC collections (started)
487 unsigned int total_collections() const { return _total_collections; }
488 unsigned int total_full_collections() const { return _total_full_collections;}
489
490 // Increment total number of GC collections (started)
491 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
492 void increment_total_collections(bool full = false) {
493 _total_collections++;
494 if (full) {
495 increment_total_full_collections();
496 }
497 }
498
499 void increment_total_full_collections() { _total_full_collections++; }
500
501 // Return the AdaptiveSizePolicy for the heap.
502 virtual AdaptiveSizePolicy* size_policy() = 0;
503
504 // Return the CollectorPolicy for the heap
505 virtual CollectorPolicy* collector_policy() const = 0;
506
507 void oop_iterate_no_header(OopClosure* cl);
508
509 // Iterate over all the ref-containing fields of all objects, calling
510 // "cl.do_oop" on each.
511 virtual void oop_iterate(ExtendedOopClosure* cl) = 0;
512
513 // Iterate over all objects, calling "cl.do_object" on each.
514 virtual void object_iterate(ObjectClosure* cl) = 0;
515
516 // Similar to object_iterate() except iterates only
517 // over live objects.
518 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
519
520 // NOTE! There is no requirement that a collector implement these
521 // functions.
522 //
523 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
524 // each address in the (reserved) heap is a member of exactly
525 // one block. The defining characteristic of a block is that it is
526 // possible to find its size, and thus to progress forward to the next
527 // block. (Blocks may be of different sizes.) Thus, blocks may
528 // represent Java objects, or they might be free blocks in a
529 // free-list-based heap (or subheap), as long as the two kinds are
530 // distinguishable and the size of each is determinable.
531
532 // Returns the address of the start of the "block" that contains the
533 // address "addr". We say "blocks" instead of "object" since some heaps
534 // may not pack objects densely; a chunk may either be an object or a
535 // non-object.
536 virtual HeapWord* block_start(const void* addr) const = 0;
537
538 // Requires "addr" to be the start of a chunk, and returns its size.
539 // "addr + size" is required to be the start of a new chunk, or the end
540 // of the active area of the heap.
541 virtual size_t block_size(const HeapWord* addr) const = 0;
542
543 // Requires "addr" to be the start of a block, and returns "TRUE" iff
544 // the block is an object.
545 virtual bool block_is_obj(const HeapWord* addr) const = 0;
546
547 // Returns the longest time (in ms) that has elapsed since the last
548 // time that any part of the heap was examined by a garbage collection.
549 virtual jlong millis_since_last_gc() = 0;
550
551 // Perform any cleanup actions necessary before allowing a verification.
552 virtual void prepare_for_verify() = 0;
553
554 // Generate any dumps preceding or following a full gc
555 void pre_full_gc_dump(GCTimer* timer);
556 void post_full_gc_dump(GCTimer* timer);
557
558 VirtualSpaceSummary create_heap_space_summary();
559 GCHeapSummary create_heap_summary();
560
561 MetaspaceSummary create_metaspace_summary();
562
563 // Print heap information on the given outputStream.
564 virtual void print_on(outputStream* st) const = 0;
565 // The default behavior is to call print_on() on tty.
566 virtual void print() const {
567 print_on(tty);
568 }
569 // Print more detailed heap information on the given
570 // outputStream. The default behavior is to call print_on(). It is
571 // up to each subclass to override it and add any additional output
572 // it needs.
573 virtual void print_extended_on(outputStream* st) const {
574 print_on(st);
575 }
576
577 virtual void print_on_error(outputStream* st) const {
578 st->print_cr("Heap:");
579 print_extended_on(st);
580 st->cr();
581
582 _barrier_set->print_on(st);
583 }
584
585 // Print all GC threads (other than the VM thread)
586 // used by this heap.
587 virtual void print_gc_threads_on(outputStream* st) const = 0;
588 // The default behavior is to call print_gc_threads_on() on tty.
589 void print_gc_threads() {
590 print_gc_threads_on(tty);
591 }
592 // Iterator for all GC threads (other than VM thread)
593 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
594
595 // Print any relevant tracing info that flags imply.
596 // Default implementation does nothing.
597 virtual void print_tracing_info() const = 0;
598
599 void print_heap_before_gc();
600 void print_heap_after_gc();
601
602 // Registering and unregistering an nmethod (compiled code) with the heap.
603 // Override with specific mechanism for each specialized heap type.
604 virtual void register_nmethod(nmethod* nm);
605 virtual void unregister_nmethod(nmethod* nm);
606
607 void trace_heap_before_gc(GCTracer* gc_tracer);
608 void trace_heap_after_gc(GCTracer* gc_tracer);
609
610 // Heap verification
611 virtual void verify(bool silent, VerifyOption option) = 0;
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 inline bool promotion_should_fail(volatile size_t* count);
619 inline 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 inline void reset_promotion_should_fail(volatile size_t* count);
624 inline 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 public:
634 // This is a convenience method that is used in cases where
635 // the actual number of GC worker threads is not pertinent but
636 // only whether there more than 0. Use of this method helps
637 // reduce the occurrence of ParallelGCThreads to uses where the
638 // actual number may be germane.
639 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; }
640
641 // Copy the current allocation context statistics for the specified contexts.
642 // For each context in contexts, set the corresponding entries in the totals
643 // and accuracy arrays to the current values held by the statistics. Each
644 // array should be of length len.
645 // Returns true if there are more stats available.
646 virtual bool copy_allocation_context_stats(const jint* contexts,
647 jlong* totals,
648 jbyte* accuracy,
649 jint len) {
650 return false;
651 }
652
653 /////////////// Unit tests ///////////////
654
655 NOT_PRODUCT(static void test_is_in();)
656 };
657
658 // Class to set and reset the GC cause for a CollectedHeap.
659
660 class GCCauseSetter : StackObj {
661 CollectedHeap* _heap;
662 GCCause::Cause _previous_cause;
663 public:
664 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
665 assert(SafepointSynchronize::is_at_safepoint(),
666 "This method manipulates heap state without locking");
667 _heap = heap;
668 _previous_cause = _heap->gc_cause();
669 _heap->set_gc_cause(cause);
670 }
671
672 ~GCCauseSetter() {
673 assert(SafepointSynchronize::is_at_safepoint(),
674 "This method manipulates heap state without locking");
675 _heap->set_gc_cause(_previous_cause);
676 }
677 };
678
679 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP