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