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,
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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 WorkGang;
54 class nmethod;
55
56 class GCMessage : public FormatBuffer<1024> {
57 public:
58 bool is_before;
59
60 public:
61 GCMessage() {}
62 };
63
64 class CollectedHeap;
65
66 class GCHeapLog : public EventLogBase<GCMessage> {
67 private:
68 void log_heap(CollectedHeap* heap, bool before);
69
70 public:
71 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
72
73 void log_heap_before(CollectedHeap* heap) {
74 log_heap(heap, true);
75 }
76 void log_heap_after(CollectedHeap* heap) {
77 log_heap(heap, false);
78 }
79 };
80
81 //
82 // CollectedHeap
83 // GenCollectedHeap
84 // G1CollectedHeap
85 // ParallelScavengeHeap
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 WorkGang* _safepoint_workers;
106
107 protected:
108 BarrierSet* _barrier_set;
109 bool _is_gc_active;
110
111 // Used for filler objects (static, but initialized in ctor).
112 static size_t _filler_array_max_size;
113
114 unsigned int _total_collections; // ... started
115 unsigned int _total_full_collections; // ... started
116 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
117 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
118
119 // Reason for current garbage collection. Should be set to
120 // a value reflecting no collection between collections.
121 GCCause::Cause _gc_cause;
122 GCCause::Cause _gc_lastcause;
123 PerfStringVariable* _perf_gc_cause;
124 PerfStringVariable* _perf_gc_lastcause;
125
126 // Constructor
127 CollectedHeap();
128
129 // Do common initializations that must follow instance construction,
130 // for example, those needing virtual calls.
131 // This code could perhaps be moved into initialize() but would
132 // be slightly more awkward because we want the latter to be a
133 // pure virtual.
134 void pre_initialize();
135
136 // Create a new tlab. All TLAB allocations must go through this.
137 virtual HeapWord* allocate_new_tlab(size_t size);
138
139 // Accumulate statistics on all tlabs.
140 virtual void accumulate_statistics_all_tlabs();
141
142 // Reinitialize tlabs before resuming mutators.
143 virtual void resize_all_tlabs();
144
145 // Allocate from the current thread's TLAB, with broken-out slow path.
146 inline static HeapWord* allocate_from_tlab(Klass* klass, Thread* thread, size_t size);
147 static HeapWord* allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size);
148
149 // Allocate an uninitialized block of the given size, or returns NULL if
150 // this is impossible.
151 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS);
152
153 // Like allocate_init, but the block returned by a successful allocation
154 // is guaranteed initialized to zeros.
155 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS);
156
157 // Helper functions for (VM) allocation.
158 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj);
159 inline static void post_allocation_setup_no_klass_install(Klass* klass,
160 HeapWord* objPtr);
161
162 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size);
163
164 inline static void post_allocation_setup_array(Klass* klass,
165 HeapWord* obj, int length);
166
167 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size);
168
169 // Clears an allocated object.
170 inline static void init_obj(HeapWord* obj, size_t size);
171
172 // Filler object utilities.
173 static inline size_t filler_array_hdr_size();
174 static inline size_t filler_array_min_size();
175
176 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
177 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
178
179 // Fill with a single array; caller must ensure filler_array_min_size() <=
180 // words <= filler_array_max_size().
181 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
182
183 // Fill with a single object (either an int array or a java.lang.Object).
184 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
185
186 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
187
188 // Verification functions
189 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
190 PRODUCT_RETURN;
191 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
192 PRODUCT_RETURN;
193 debug_only(static void check_for_valid_allocation_state();)
194
195 public:
196 enum Name {
197 GenCollectedHeap,
198 ParallelScavengeHeap,
199 G1CollectedHeap
200 };
201
202 static inline size_t filler_array_max_size() {
203 return _filler_array_max_size;
204 }
205
206 virtual Name kind() const = 0;
207
208 virtual const char* name() const = 0;
209
210 /**
211 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
212 * and JNI_OK on success.
213 */
214 virtual jint initialize() = 0;
215
216 // In many heaps, there will be a need to perform some initialization activities
217 // after the Universe is fully formed, but before general heap allocation is allowed.
218 // This is the correct place to place such initialization methods.
219 virtual void post_initialize() = 0;
220
221 // Stop any onging concurrent work and prepare for exit.
222 virtual void stop() {}
223
224 void initialize_reserved_region(HeapWord *start, HeapWord *end);
225 MemRegion reserved_region() const { return _reserved; }
226 address base() const { return (address)reserved_region().start(); }
227
228 virtual size_t capacity() const = 0;
229 virtual size_t used() const = 0;
230
231 // Return "true" if the part of the heap that allocates Java
232 // objects has reached the maximal committed limit that it can
233 // reach, without a garbage collection.
234 virtual bool is_maximal_no_gc() const = 0;
235
236 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
237 // memory that the vm could make available for storing 'normal' java objects.
238 // This is based on the reserved address space, but should not include space
239 // that the vm uses internally for bookkeeping or temporary storage
240 // (e.g., in the case of the young gen, one of the survivor
241 // spaces).
242 virtual size_t max_capacity() const = 0;
243
244 // Returns "TRUE" if "p" points into the reserved area of the heap.
245 bool is_in_reserved(const void* p) const {
246 return _reserved.contains(p);
247 }
248
249 bool is_in_reserved_or_null(const void* p) const {
250 return p == NULL || is_in_reserved(p);
251 }
252
253 // Returns "TRUE" iff "p" points into the committed areas of the heap.
254 // This method can be expensive so avoid using it in performance critical
255 // code.
256 virtual bool is_in(const void* p) const = 0;
257
258 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
259
260 // Let's define some terms: a "closed" subset of a heap is one that
261 //
262 // 1) contains all currently-allocated objects, and
263 //
264 // 2) is closed under reference: no object in the closed subset
265 // references one outside the closed subset.
266 //
267 // Membership in a heap's closed subset is useful for assertions.
268 // Clearly, the entire heap is a closed subset, so the default
269 // implementation is to use "is_in_reserved". But this may not be too
270 // liberal to perform useful checking. Also, the "is_in" predicate
271 // defines a closed subset, but may be too expensive, since "is_in"
272 // verifies that its argument points to an object head. The
273 // "closed_subset" method allows a heap to define an intermediate
274 // predicate, allowing more precise checking than "is_in_reserved" at
275 // lower cost than "is_in."
276
277 // One important case is a heap composed of disjoint contiguous spaces,
278 // such as the Garbage-First collector. Such heaps have a convenient
279 // closed subset consisting of the allocated portions of those
280 // contiguous spaces.
281
282 // Return "TRUE" iff the given pointer points into the heap's defined
283 // closed subset (which defaults to the entire heap).
284 virtual bool is_in_closed_subset(const void* p) const {
285 return is_in_reserved(p);
286 }
287
288 bool is_in_closed_subset_or_null(const void* p) const {
289 return p == NULL || is_in_closed_subset(p);
290 }
291
292 // An object is scavengable if its location may move during a scavenge.
293 // (A scavenge is a GC which is not a full GC.)
294 virtual bool is_scavengable(const void *p) = 0;
295
296 void set_gc_cause(GCCause::Cause v) {
297 if (UsePerfData) {
298 _gc_lastcause = _gc_cause;
299 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
300 _perf_gc_cause->set_value(GCCause::to_string(v));
301 }
302 _gc_cause = v;
303 }
304 GCCause::Cause gc_cause() { return _gc_cause; }
305
306 // General obj/array allocation facilities.
307 inline static oop obj_allocate(Klass* klass, int size, TRAPS);
308 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS);
309 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS);
310 inline static oop class_allocate(Klass* klass, int size, TRAPS);
311
312 // Raw memory allocation facilities
313 // The obj and array allocate methods are covers for these methods.
314 // mem_allocate() should never be
315 // called to allocate TLABs, only individual objects.
316 virtual HeapWord* mem_allocate(size_t size,
317 bool* gc_overhead_limit_was_exceeded) = 0;
318
319 // Utilities for turning raw memory into filler objects.
320 //
321 // min_fill_size() is the smallest region that can be filled.
322 // fill_with_objects() can fill arbitrary-sized regions of the heap using
323 // multiple objects. fill_with_object() is for regions known to be smaller
324 // than the largest array of integers; it uses a single object to fill the
325 // region and has slightly less overhead.
326 static size_t min_fill_size() {
327 return size_t(align_object_size(oopDesc::header_size()));
328 }
329
330 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
331
332 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
333 static void fill_with_object(MemRegion region, bool zap = true) {
334 fill_with_object(region.start(), region.word_size(), zap);
335 }
336 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
337 fill_with_object(start, pointer_delta(end, start), zap);
338 }
339
340 // Return the address "addr" aligned by "alignment_in_bytes" if such
341 // an address is below "end". Return NULL otherwise.
342 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
343 HeapWord* end,
344 unsigned short alignment_in_bytes);
345
346 // Some heaps may offer a contiguous region for shared non-blocking
347 // allocation, via inlined code (by exporting the address of the top and
348 // end fields defining the extent of the contiguous allocation region.)
349
350 // This function returns "true" iff the heap supports this kind of
351 // allocation. (Default is "no".)
352 virtual bool supports_inline_contig_alloc() const {
353 return false;
354 }
355 // These functions return the addresses of the fields that define the
356 // boundaries of the contiguous allocation area. (These fields should be
357 // physically near to one another.)
358 virtual HeapWord* volatile* top_addr() const {
359 guarantee(false, "inline contiguous allocation not supported");
360 return NULL;
361 }
362 virtual HeapWord** end_addr() const {
363 guarantee(false, "inline contiguous allocation not supported");
364 return NULL;
365 }
366
367 // Some heaps may be in an unparseable state at certain times between
368 // collections. This may be necessary for efficient implementation of
369 // certain allocation-related activities. Calling this function before
370 // attempting to parse a heap ensures that the heap is in a parsable
371 // state (provided other concurrent activity does not introduce
372 // unparsability). It is normally expected, therefore, that this
373 // method is invoked with the world stopped.
374 // NOTE: if you override this method, make sure you call
375 // super::ensure_parsability so that the non-generational
376 // part of the work gets done. See implementation of
377 // CollectedHeap::ensure_parsability and, for instance,
378 // that of GenCollectedHeap::ensure_parsability().
379 // The argument "retire_tlabs" controls whether existing TLABs
380 // are merely filled or also retired, thus preventing further
381 // allocation from them and necessitating allocation of new TLABs.
382 virtual void ensure_parsability(bool retire_tlabs);
383
384 // Section on thread-local allocation buffers (TLABs)
385 // If the heap supports thread-local allocation buffers, it should override
386 // the following methods:
387 // Returns "true" iff the heap supports thread-local allocation buffers.
388 // The default is "no".
389 virtual bool supports_tlab_allocation() const = 0;
390
391 // The amount of space available for thread-local allocation buffers.
392 virtual size_t tlab_capacity(Thread *thr) const = 0;
393
394 // The amount of used space for thread-local allocation buffers for the given thread.
395 virtual size_t tlab_used(Thread *thr) const = 0;
396
397 virtual size_t max_tlab_size() const;
398
399 // An estimate of the maximum allocation that could be performed
400 // for thread-local allocation buffers without triggering any
401 // collection or expansion activity.
402 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
403 guarantee(false, "thread-local allocation buffers not supported");
404 return 0;
405 }
406
407 // Can a compiler initialize a new object without store barriers?
408 // This permission only extends from the creation of a new object
409 // via a TLAB up to the first subsequent safepoint. If such permission
410 // is granted for this heap type, the compiler promises to call
411 // defer_store_barrier() below on any slow path allocation of
412 // a new object for which such initializing store barriers will
413 // have been elided.
414 virtual bool can_elide_tlab_store_barriers() const = 0;
415
416 // If a compiler is eliding store barriers for TLAB-allocated objects,
417 // there is probably a corresponding slow path which can produce
418 // an object allocated anywhere. The compiler's runtime support
419 // promises to call this function on such a slow-path-allocated
420 // object before performing initializations that have elided
421 // store barriers. Returns new_obj, or maybe a safer copy thereof.
422 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
423
424 // Answers whether an initializing store to a new object currently
425 // allocated at the given address doesn't need a store
426 // barrier. Returns "true" if it doesn't need an initializing
427 // store barrier; answers "false" if it does.
428 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
429
430 // If a compiler is eliding store barriers for TLAB-allocated objects,
431 // we will be informed of a slow-path allocation by a call
432 // to new_store_pre_barrier() above. Such a call precedes the
433 // initialization of the object itself, and no post-store-barriers will
434 // be issued. Some heap types require that the barrier strictly follows
435 // the initializing stores. (This is currently implemented by deferring the
436 // barrier until the next slow-path allocation or gc-related safepoint.)
437 // This interface answers whether a particular heap type needs the card
438 // mark to be thus strictly sequenced after the stores.
439 virtual bool card_mark_must_follow_store() const = 0;
440
441 // If the CollectedHeap was asked to defer a store barrier above,
442 // this informs it to flush such a deferred store barrier to the
443 // remembered set.
444 virtual void flush_deferred_store_barrier(JavaThread* thread);
445
446 // Perform a collection of the heap; intended for use in implementing
447 // "System.gc". This probably implies as full a collection as the
448 // "CollectedHeap" supports.
449 virtual void collect(GCCause::Cause cause) = 0;
450
451 // Perform a full collection
452 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
453
454 // This interface assumes that it's being called by the
455 // vm thread. It collects the heap assuming that the
456 // heap lock is already held and that we are executing in
457 // the context of the vm thread.
458 virtual void collect_as_vm_thread(GCCause::Cause cause);
459
460 // Returns the barrier set for this heap
461 BarrierSet* barrier_set() { return _barrier_set; }
462 void set_barrier_set(BarrierSet* barrier_set);
463
464 // Returns "true" iff there is a stop-world GC in progress. (I assume
465 // that it should answer "false" for the concurrent part of a concurrent
466 // collector -- dld).
467 bool is_gc_active() const { return _is_gc_active; }
468
469 // Total number of GC collections (started)
470 unsigned int total_collections() const { return _total_collections; }
471 unsigned int total_full_collections() const { return _total_full_collections;}
472
473 // Increment total number of GC collections (started)
474 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
475 void increment_total_collections(bool full = false) {
476 _total_collections++;
477 if (full) {
478 increment_total_full_collections();
479 }
480 }
481
482 void increment_total_full_collections() { _total_full_collections++; }
483
484 // Return the CollectorPolicy for the heap
485 virtual CollectorPolicy* collector_policy() const = 0;
486
487 // Iterate over all objects, calling "cl.do_object" on each.
488 virtual void object_iterate(ObjectClosure* cl) = 0;
489
490 // Similar to object_iterate() except iterates only
491 // over live objects.
492 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
493
494 // NOTE! There is no requirement that a collector implement these
495 // functions.
496 //
497 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
498 // each address in the (reserved) heap is a member of exactly
499 // one block. The defining characteristic of a block is that it is
500 // possible to find its size, and thus to progress forward to the next
501 // block. (Blocks may be of different sizes.) Thus, blocks may
502 // represent Java objects, or they might be free blocks in a
503 // free-list-based heap (or subheap), as long as the two kinds are
504 // distinguishable and the size of each is determinable.
505
506 // Returns the address of the start of the "block" that contains the
507 // address "addr". We say "blocks" instead of "object" since some heaps
508 // may not pack objects densely; a chunk may either be an object or a
509 // non-object.
510 virtual HeapWord* block_start(const void* addr) const = 0;
511
512 // Requires "addr" to be the start of a chunk, and returns its size.
513 // "addr + size" is required to be the start of a new chunk, or the end
514 // of the active area of the heap.
515 virtual size_t block_size(const HeapWord* addr) const = 0;
516
517 // Requires "addr" to be the start of a block, and returns "TRUE" iff
518 // the block is an object.
519 virtual bool block_is_obj(const HeapWord* addr) const = 0;
520
521 // Returns the longest time (in ms) that has elapsed since the last
522 // time that any part of the heap was examined by a garbage collection.
523 virtual jlong millis_since_last_gc() = 0;
524
525 // Perform any cleanup actions necessary before allowing a verification.
526 virtual void prepare_for_verify() = 0;
527
528 // Generate any dumps preceding or following a full gc
529 private:
530 void full_gc_dump(GCTimer* timer, bool before);
531 public:
532 void pre_full_gc_dump(GCTimer* timer);
533 void post_full_gc_dump(GCTimer* timer);
534
535 VirtualSpaceSummary create_heap_space_summary();
536 GCHeapSummary create_heap_summary();
537
538 MetaspaceSummary create_metaspace_summary();
539
540 // Print heap information on the given outputStream.
541 virtual void print_on(outputStream* st) const = 0;
542 // The default behavior is to call print_on() on tty.
543 virtual void print() const {
544 print_on(tty);
545 }
546 // Print more detailed heap information on the given
547 // outputStream. The default behavior is to call print_on(). It is
548 // up to each subclass to override it and add any additional output
549 // it needs.
550 virtual void print_extended_on(outputStream* st) const {
551 print_on(st);
552 }
553
554 virtual void print_on_error(outputStream* st) const;
555
556 // Print all GC threads (other than the VM thread)
557 // used by this heap.
558 virtual void print_gc_threads_on(outputStream* st) const = 0;
559 // The default behavior is to call print_gc_threads_on() on tty.
560 void print_gc_threads() {
561 print_gc_threads_on(tty);
562 }
563 // Iterator for all GC threads (other than VM thread)
564 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
565
566 // Print any relevant tracing info that flags imply.
567 // Default implementation does nothing.
568 virtual void print_tracing_info() const = 0;
569
570 void print_heap_before_gc();
571 void print_heap_after_gc();
572
573 // Registering and unregistering an nmethod (compiled code) with the heap.
574 // Override with specific mechanism for each specialized heap type.
575 virtual void register_nmethod(nmethod* nm);
576 virtual void unregister_nmethod(nmethod* nm);
577
578 void trace_heap_before_gc(const GCTracer* gc_tracer);
579 void trace_heap_after_gc(const GCTracer* gc_tracer);
580
581 // Heap verification
582 virtual void verify(VerifyOption option) = 0;
583
584 // Return true if concurrent phase control (via
585 // request_concurrent_phase_control) is supported by this collector.
586 // The default implementation returns false.
587 virtual bool supports_concurrent_phase_control() const;
588
589 // Return a NULL terminated array of concurrent phase names provided
590 // by this collector. Supports Whitebox testing. These are the
591 // names recognized by request_concurrent_phase(). The default
592 // implementation returns an array of one NULL element.
593 virtual const char* const* concurrent_phases() const;
594
595 // Request the collector enter the indicated concurrent phase, and
596 // wait until it does so. Supports WhiteBox testing. Only one
597 // request may be active at a time. Phases are designated by name;
598 // the set of names and their meaning is GC-specific. Once the
599 // requested phase has been reached, the collector will attempt to
600 // avoid transitioning to a new phase until a new request is made.
601 // [Note: A collector might not be able to remain in a given phase.
602 // For example, a full collection might cancel an in-progress
603 // concurrent collection.]
604 //
605 // Returns true when the phase is reached. Returns false for an
606 // unknown phase. The default implementation returns false.
607 virtual bool request_concurrent_phase(const char* phase);
608
609 // Provides a thread pool to SafepointSynchronize to use
610 // for parallel safepoint cleanup.
611 // GCs that use a GC worker thread pool may want to share
612 // it for use during safepoint cleanup. This is only possible
613 // if the GC can pause and resume concurrent work (e.g. G1
614 // concurrent marking) for an intermittent non-GC safepoint.
615 // If this method returns NULL, SafepointSynchronize will
616 // perform cleanup tasks serially in the VMThread.
617 virtual WorkGang* get_safepoint_workers() { return _safepoint_workers; }
618
619 // Non product verification and debugging.
620 #ifndef PRODUCT
621 // Support for PromotionFailureALot. Return true if it's time to cause a
622 // promotion failure. The no-argument version uses
623 // this->_promotion_failure_alot_count as the counter.
624 inline bool promotion_should_fail(volatile size_t* count);
625 inline bool promotion_should_fail();
626
627 // Reset the PromotionFailureALot counters. Should be called at the end of a
628 // GC in which promotion failure occurred.
629 inline void reset_promotion_should_fail(volatile size_t* count);
630 inline void reset_promotion_should_fail();
631 #endif // #ifndef PRODUCT
632
633 #ifdef ASSERT
634 static int fired_fake_oom() {
635 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
636 }
637 #endif
638
639 public:
640 // Copy the current allocation context statistics for the specified contexts.
641 // For each context in contexts, set the corresponding entries in the totals
642 // and accuracy arrays to the current values held by the statistics. Each
643 // array should be of length len.
644 // Returns true if there are more stats available.
645 virtual bool copy_allocation_context_stats(const jint* contexts,
646 jlong* totals,
647 jbyte* accuracy,
648 jint len) {
649 return false;
650 }
651
652 };
653
654 // Class to set and reset the GC cause for a CollectedHeap.
655
656 class GCCauseSetter : StackObj {
657 CollectedHeap* _heap;
658 GCCause::Cause _previous_cause;
659 public:
660 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
661 assert(SafepointSynchronize::is_at_safepoint(),
662 "This method manipulates heap state without locking");
663 _heap = heap;
664 _previous_cause = _heap->gc_cause();
665 _heap->set_gc_cause(cause);
666 }
667
668 ~GCCauseSetter() {
669 assert(SafepointSynchronize::is_at_safepoint(),
670 "This method manipulates heap state without locking");
671 _heap->set_gc_cause(_previous_cause);
672 }
673 };
674
675 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP