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 21 * questions. 22 * 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 private: 89 #ifdef ASSERT 90 static int _fire_out_of_memory_count; 91 #endif 92 93 // Used for filler objects (static, but initialized in ctor). 94 static size_t _filler_array_max_size; 95 96 GCHeapLog* _gc_heap_log; 97 98 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used 99 bool _defer_initial_card_mark; 100 101 MemRegion _reserved; 102 103 protected: 104 BarrierSet* _barrier_set; 105 bool _is_gc_active; 106 uint _n_par_threads; 107 108 unsigned int _total_collections; // ... started 109 unsigned int _total_full_collections; // ... started 110 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 111 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 112 113 // Reason for current garbage collection. Should be set to 114 // a value reflecting no collection between collections. 115 GCCause::Cause _gc_cause; 116 GCCause::Cause _gc_lastcause; 117 PerfStringVariable* _perf_gc_cause; 118 PerfStringVariable* _perf_gc_lastcause; 119 120 // Constructor 121 CollectedHeap(); 122 123 // Do common initializations that must follow instance construction, 124 // for example, those needing virtual calls. 125 // This code could perhaps be moved into initialize() but would 126 // be slightly more awkward because we want the latter to be a 127 // pure virtual. 128 void pre_initialize(); 129 130 // Create a new tlab. All TLAB allocations must go through this. 131 virtual HeapWord* allocate_new_tlab(size_t size); 132 133 // Accumulate statistics on all tlabs. 134 virtual void accumulate_statistics_all_tlabs(); 135 136 // Reinitialize tlabs before resuming mutators. 137 virtual void resize_all_tlabs(); 138 139 // Allocate from the current thread's TLAB, with broken-out slow path. 140 inline static HeapWord* allocate_from_tlab(KlassHandle klass, Thread* thread, size_t size); 141 static HeapWord* allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size); 142 143 // Allocate an uninitialized block of the given size, or returns NULL if 144 // this is impossible. 145 inline static HeapWord* common_mem_allocate_noinit(KlassHandle klass, size_t size, TRAPS); 146 147 // Like allocate_init, but the block returned by a successful allocation 148 // is guaranteed initialized to zeros. 149 inline static HeapWord* common_mem_allocate_init(KlassHandle klass, size_t size, TRAPS); 150 151 // Helper functions for (VM) allocation. 152 inline static void post_allocation_setup_common(KlassHandle klass, HeapWord* obj); 153 inline static void post_allocation_setup_no_klass_install(KlassHandle klass, 154 HeapWord* objPtr); 155 156 inline static void post_allocation_setup_obj(KlassHandle klass, HeapWord* obj, int size); 157 158 inline static void post_allocation_setup_array(KlassHandle klass, 159 HeapWord* obj, int length); 160 161 // Clears an allocated object. 162 inline static void init_obj(HeapWord* obj, size_t size); 163 164 // Filler object utilities. 165 static inline size_t filler_array_hdr_size(); 166 static inline size_t filler_array_min_size(); 167 168 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 169 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 170 171 // Fill with a single array; caller must ensure filler_array_min_size() <= 172 // words <= filler_array_max_size(). 173 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 174 175 // Fill with a single object (either an int array or a java.lang.Object). 176 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 177 178 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 179 180 // Verification functions 181 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) 182 PRODUCT_RETURN; 183 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 184 PRODUCT_RETURN; 185 debug_only(static void check_for_valid_allocation_state();) 186 187 public: 188 enum Name { 189 Abstract, 190 SharedHeap, 191 GenCollectedHeap, 192 ParallelScavengeHeap, 193 G1CollectedHeap 194 }; 195 196 static inline size_t filler_array_max_size() { 197 return _filler_array_max_size; 198 } 199 200 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; } 201 202 /** 203 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 204 * and JNI_OK on success. 205 */ 206 virtual jint initialize() = 0; 207 208 // In many heaps, there will be a need to perform some initialization activities 209 // after the Universe is fully formed, but before general heap allocation is allowed. 210 // This is the correct place to place such initialization methods. 211 virtual void post_initialize() = 0; 212 213 // Stop any onging concurrent work and prepare for exit. 214 virtual void stop() {} 215 216 void initialize_reserved_region(HeapWord *start, HeapWord *end); 217 MemRegion reserved_region() const { return _reserved; } 218 address base() const { return (address)reserved_region().start(); } 219 220 virtual size_t capacity() const = 0; 221 virtual size_t used() const = 0; 222 223 // Return "true" if the part of the heap that allocates Java 224 // objects has reached the maximal committed limit that it can 225 // reach, without a garbage collection. 226 virtual bool is_maximal_no_gc() const = 0; 227 228 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 229 // memory that the vm could make available for storing 'normal' java objects. 230 // This is based on the reserved address space, but should not include space 231 // that the vm uses internally for bookkeeping or temporary storage 232 // (e.g., in the case of the young gen, one of the survivor 233 // spaces). 234 virtual size_t max_capacity() const = 0; 235 236 // Returns "TRUE" if "p" points into the reserved area of the heap. 237 bool is_in_reserved(const void* p) const { 238 return _reserved.contains(p); 239 } 240 241 bool is_in_reserved_or_null(const void* p) const { 242 return p == NULL || is_in_reserved(p); 243 } 244 245 // Returns "TRUE" iff "p" points into the committed areas of the heap. 246 // Since this method can be expensive in general, we restrict its 247 // use to assertion checking only. 248 virtual bool is_in(const void* p) const = 0; 249 250 bool is_in_or_null(const void* p) const { 251 return p == NULL || is_in(p); 252 } 253 254 bool is_in_place(Metadata** p) { 255 return !Universe::heap()->is_in(p); 256 } 257 bool is_in_place(oop* p) { return Universe::heap()->is_in(p); } 258 bool is_in_place(narrowOop* p) { 259 oop o = oopDesc::load_decode_heap_oop_not_null(p); 260 return Universe::heap()->is_in((const void*)o); 261 } 262 263 // Let's define some terms: a "closed" subset of a heap is one that 264 // 265 // 1) contains all currently-allocated objects, and 266 // 267 // 2) is closed under reference: no object in the closed subset 268 // references one outside the closed subset. 269 // 270 // Membership in a heap's closed subset is useful for assertions. 271 // Clearly, the entire heap is a closed subset, so the default 272 // implementation is to use "is_in_reserved". But this may not be too 273 // liberal to perform useful checking. Also, the "is_in" predicate 274 // defines a closed subset, but may be too expensive, since "is_in" 275 // verifies that its argument points to an object head. The 276 // "closed_subset" method allows a heap to define an intermediate 277 // predicate, allowing more precise checking than "is_in_reserved" at 278 // lower cost than "is_in." 279 280 // One important case is a heap composed of disjoint contiguous spaces, 281 // such as the Garbage-First collector. Such heaps have a convenient 282 // closed subset consisting of the allocated portions of those 283 // contiguous spaces. 284 285 // Return "TRUE" iff the given pointer points into the heap's defined 286 // closed subset (which defaults to the entire heap). 287 virtual bool is_in_closed_subset(const void* p) const { 288 return is_in_reserved(p); 289 } 290 291 bool is_in_closed_subset_or_null(const void* p) const { 292 return p == NULL || is_in_closed_subset(p); 293 } 294 295 #ifdef ASSERT 296 // Returns true if "p" is in the part of the 297 // heap being collected. 298 virtual bool is_in_partial_collection(const void *p) = 0; 299 #endif 300 301 // An object is scavengable if its location may move during a scavenge. 302 // (A scavenge is a GC which is not a full GC.) 303 virtual bool is_scavengable(const void *p) = 0; 304 305 void set_gc_cause(GCCause::Cause v) { 306 if (UsePerfData) { 307 _gc_lastcause = _gc_cause; 308 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 309 _perf_gc_cause->set_value(GCCause::to_string(v)); 310 } 311 _gc_cause = v; 312 } 313 GCCause::Cause gc_cause() { return _gc_cause; } 314 315 // Number of threads currently working on GC tasks. 316 uint n_par_threads() { return _n_par_threads; } 317 318 // May be overridden to set additional parallelism. 319 virtual void set_par_threads(uint t) { _n_par_threads = t; }; 320 321 // General obj/array allocation facilities. 322 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS); 323 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS); 324 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS); 325 326 inline static void post_allocation_install_obj_klass(KlassHandle klass, 327 oop obj); 328 329 // Raw memory allocation facilities 330 // The obj and array allocate methods are covers for these methods. 331 // mem_allocate() should never be 332 // called to allocate TLABs, only individual objects. 333 virtual HeapWord* mem_allocate(size_t size, 334 bool* gc_overhead_limit_was_exceeded) = 0; 335 336 // Utilities for turning raw memory into filler objects. 337 // 338 // min_fill_size() is the smallest region that can be filled. 339 // fill_with_objects() can fill arbitrary-sized regions of the heap using 340 // multiple objects. fill_with_object() is for regions known to be smaller 341 // than the largest array of integers; it uses a single object to fill the 342 // region and has slightly less overhead. 343 static size_t min_fill_size() { 344 return size_t(align_object_size(oopDesc::header_size())); 345 } 346 347 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 348 349 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 350 static void fill_with_object(MemRegion region, bool zap = true) { 351 fill_with_object(region.start(), region.word_size(), zap); 352 } 353 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 354 fill_with_object(start, pointer_delta(end, start), zap); 355 } 356 357 // Return the address "addr" aligned by "alignment_in_bytes" if such 358 // an address is below "end". Return NULL otherwise. 359 inline static HeapWord* align_allocation_or_fail(HeapWord* addr, 360 HeapWord* end, 361 unsigned short alignment_in_bytes); 362 363 // Some heaps may offer a contiguous region for shared non-blocking 364 // allocation, via inlined code (by exporting the address of the top and 365 // end fields defining the extent of the contiguous allocation region.) 366 367 // This function returns "true" iff the heap supports this kind of 368 // allocation. (Default is "no".) 369 virtual bool supports_inline_contig_alloc() const { 370 return false; 371 } 372 // These functions return the addresses of the fields that define the 373 // boundaries of the contiguous allocation area. (These fields should be 374 // physically near to one another.) 375 virtual HeapWord** top_addr() const { 376 guarantee(false, "inline contiguous allocation not supported"); 377 return NULL; 378 } 379 virtual HeapWord** end_addr() const { 380 guarantee(false, "inline contiguous allocation not supported"); 381 return NULL; 382 } 383 384 // Some heaps may be in an unparseable state at certain times between 385 // collections. This may be necessary for efficient implementation of 386 // certain allocation-related activities. Calling this function before 387 // attempting to parse a heap ensures that the heap is in a parsable 388 // state (provided other concurrent activity does not introduce 389 // unparsability). It is normally expected, therefore, that this 390 // method is invoked with the world stopped. 391 // NOTE: if you override this method, make sure you call 392 // super::ensure_parsability so that the non-generational 393 // part of the work gets done. See implementation of 394 // CollectedHeap::ensure_parsability and, for instance, 395 // that of GenCollectedHeap::ensure_parsability(). 396 // The argument "retire_tlabs" controls whether existing TLABs 397 // are merely filled or also retired, thus preventing further 398 // allocation from them and necessitating allocation of new TLABs. 399 virtual void ensure_parsability(bool retire_tlabs); 400 401 // Section on thread-local allocation buffers (TLABs) 402 // If the heap supports thread-local allocation buffers, it should override 403 // the following methods: 404 // Returns "true" iff the heap supports thread-local allocation buffers. 405 // The default is "no". 406 virtual bool supports_tlab_allocation() const = 0; 407 408 // The amount of space available for thread-local allocation buffers. 409 virtual size_t tlab_capacity(Thread *thr) const = 0; 410 411 // The amount of used space for thread-local allocation buffers for the given thread. 412 virtual size_t tlab_used(Thread *thr) const = 0; 413 414 virtual size_t max_tlab_size() const; 415 416 // An estimate of the maximum allocation that could be performed 417 // for thread-local allocation buffers without triggering any 418 // collection or expansion activity. 419 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 420 guarantee(false, "thread-local allocation buffers not supported"); 421 return 0; 422 } 423 424 // Can a compiler initialize a new object without store barriers? 425 // This permission only extends from the creation of a new object 426 // via a TLAB up to the first subsequent safepoint. If such permission 427 // is granted for this heap type, the compiler promises to call 428 // defer_store_barrier() below on any slow path allocation of 429 // a new object for which such initializing store barriers will 430 // have been elided. 431 virtual bool can_elide_tlab_store_barriers() const = 0; 432 433 // If a compiler is eliding store barriers for TLAB-allocated objects, 434 // there is probably a corresponding slow path which can produce 435 // an object allocated anywhere. The compiler's runtime support 436 // promises to call this function on such a slow-path-allocated 437 // object before performing initializations that have elided 438 // store barriers. Returns new_obj, or maybe a safer copy thereof. 439 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj); 440 441 // Answers whether an initializing store to a new object currently 442 // allocated at the given address doesn't need a store 443 // barrier. Returns "true" if it doesn't need an initializing 444 // store barrier; answers "false" if it does. 445 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0; 446 447 // If a compiler is eliding store barriers for TLAB-allocated objects, 448 // we will be informed of a slow-path allocation by a call 449 // to new_store_pre_barrier() above. Such a call precedes the 450 // initialization of the object itself, and no post-store-barriers will 451 // be issued. Some heap types require that the barrier strictly follows 452 // the initializing stores. (This is currently implemented by deferring the 453 // barrier until the next slow-path allocation or gc-related safepoint.) 454 // This interface answers whether a particular heap type needs the card 455 // mark to be thus strictly sequenced after the stores. 456 virtual bool card_mark_must_follow_store() const = 0; 457 458 // If the CollectedHeap was asked to defer a store barrier above, 459 // this informs it to flush such a deferred store barrier to the 460 // remembered set. 461 virtual void flush_deferred_store_barrier(JavaThread* thread); 462 463 // Does this heap support heap inspection (+PrintClassHistogram?) 464 virtual bool supports_heap_inspection() const = 0; 465 466 // Perform a collection of the heap; intended for use in implementing 467 // "System.gc". This probably implies as full a collection as the 468 // "CollectedHeap" supports. 469 virtual void collect(GCCause::Cause cause) = 0; 470 471 // Perform a full collection 472 virtual void do_full_collection(bool clear_all_soft_refs) = 0; 473 474 // This interface assumes that it's being called by the 475 // vm thread. It collects the heap assuming that the 476 // heap lock is already held and that we are executing in 477 // the context of the vm thread. 478 virtual void collect_as_vm_thread(GCCause::Cause cause); 479 480 // Returns the barrier set for this heap 481 BarrierSet* barrier_set() { return _barrier_set; } 482 483 // Returns "true" iff there is a stop-world GC in progress. (I assume 484 // that it should answer "false" for the concurrent part of a concurrent 485 // collector -- dld). 486 bool is_gc_active() const { return _is_gc_active; } 487 488 // Total number of GC collections (started) 489 unsigned int total_collections() const { return _total_collections; } 490 unsigned int total_full_collections() const { return _total_full_collections;} 491 492 // Increment total number of GC collections (started) 493 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 494 void increment_total_collections(bool full = false) { 495 _total_collections++; 496 if (full) { 497 increment_total_full_collections(); 498 } 499 } 500 501 void increment_total_full_collections() { _total_full_collections++; } 502 503 // Return the AdaptiveSizePolicy for the heap. 504 virtual AdaptiveSizePolicy* size_policy() = 0; 505 506 // Return the CollectorPolicy for the heap 507 virtual CollectorPolicy* collector_policy() const = 0; 508 509 void oop_iterate_no_header(OopClosure* cl); 510 511 // Iterate over all the ref-containing fields of all objects, calling 512 // "cl.do_oop" on each. 513 virtual void oop_iterate(ExtendedOopClosure* cl) = 0; 514 515 // Iterate over all objects, calling "cl.do_object" on each. 516 virtual void object_iterate(ObjectClosure* cl) = 0; 517 518 // Similar to object_iterate() except iterates only 519 // over live objects. 520 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 521 522 // NOTE! There is no requirement that a collector implement these 523 // functions. 524 // 525 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 526 // each address in the (reserved) heap is a member of exactly 527 // one block. The defining characteristic of a block is that it is 528 // possible to find its size, and thus to progress forward to the next 529 // block. (Blocks may be of different sizes.) Thus, blocks may 530 // represent Java objects, or they might be free blocks in a 531 // free-list-based heap (or subheap), as long as the two kinds are 532 // distinguishable and the size of each is determinable. 533 534 // Returns the address of the start of the "block" that contains the 535 // address "addr". We say "blocks" instead of "object" since some heaps 536 // may not pack objects densely; a chunk may either be an object or a 537 // non-object. 538 virtual HeapWord* block_start(const void* addr) const = 0; 539 540 // Requires "addr" to be the start of a chunk, and returns its size. 541 // "addr + size" is required to be the start of a new chunk, or the end 542 // of the active area of the heap. 543 virtual size_t block_size(const HeapWord* addr) const = 0; 544 545 // Requires "addr" to be the start of a block, and returns "TRUE" iff 546 // the block is an object. 547 virtual bool block_is_obj(const HeapWord* addr) const = 0; 548 549 // Returns the longest time (in ms) that has elapsed since the last 550 // time that any part of the heap was examined by a garbage collection. 551 virtual jlong millis_since_last_gc() = 0; 552 553 // Perform any cleanup actions necessary before allowing a verification. 554 virtual void prepare_for_verify() = 0; 555 556 // Generate any dumps preceding or following a full gc 557 void pre_full_gc_dump(GCTimer* timer); 558 void post_full_gc_dump(GCTimer* timer); 559 560 VirtualSpaceSummary create_heap_space_summary(); 561 GCHeapSummary create_heap_summary(); 562 563 MetaspaceSummary create_metaspace_summary(); 564 565 // Print heap information on the given outputStream. 566 virtual void print_on(outputStream* st) const = 0; 567 // The default behavior is to call print_on() on tty. 568 virtual void print() const { 569 print_on(tty); 570 } 571 // Print more detailed heap information on the given 572 // outputStream. The default behavior is to call print_on(). It is 573 // up to each subclass to override it and add any additional output 574 // it needs. 575 virtual void print_extended_on(outputStream* st) const { 576 print_on(st); 577 } 578 579 virtual void print_on_error(outputStream* st) const { 580 st->print_cr("Heap:"); 581 print_extended_on(st); 582 st->cr(); 583 584 _barrier_set->print_on(st); 585 } 586 587 // Print all GC threads (other than the VM thread) 588 // used by this heap. 589 virtual void print_gc_threads_on(outputStream* st) const = 0; 590 // The default behavior is to call print_gc_threads_on() on tty. 591 void print_gc_threads() { 592 print_gc_threads_on(tty); 593 } 594 // Iterator for all GC threads (other than VM thread) 595 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 596 597 // Print any relevant tracing info that flags imply. 598 // Default implementation does nothing. 599 virtual void print_tracing_info() const = 0; 600 601 void print_heap_before_gc(); 602 void print_heap_after_gc(); 603 604 // Registering and unregistering an nmethod (compiled code) with the heap. 605 // Override with specific mechanism for each specialized heap type. 606 virtual void register_nmethod(nmethod* nm); 607 virtual void unregister_nmethod(nmethod* nm); 608 609 void trace_heap_before_gc(const GCTracer* gc_tracer); 610 void trace_heap_after_gc(const GCTracer* gc_tracer); 611 612 // Heap verification 613 virtual void verify(bool silent, VerifyOption option) = 0; 614 615 // Non product verification and debugging. 616 #ifndef PRODUCT 617 // Support for PromotionFailureALot. Return true if it's time to cause a 618 // promotion failure. The no-argument version uses 619 // this->_promotion_failure_alot_count as the counter. 620 inline bool promotion_should_fail(volatile size_t* count); 621 inline bool promotion_should_fail(); 622 623 // Reset the PromotionFailureALot counters. Should be called at the end of a 624 // GC in which promotion failure occurred. 625 inline void reset_promotion_should_fail(volatile size_t* count); 626 inline void reset_promotion_should_fail(); 627 #endif // #ifndef PRODUCT 628 629 #ifdef ASSERT 630 static int fired_fake_oom() { 631 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 632 } 633 #endif 634 635 public: 636 // This is a convenience method that is used in cases where 637 // the actual number of GC worker threads is not pertinent but 638 // only whether there more than 0. Use of this method helps 639 // reduce the occurrence of ParallelGCThreads to uses where the 640 // actual number may be germane. 641 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; } 642 643 // Copy the current allocation context statistics for the specified contexts. 644 // For each context in contexts, set the corresponding entries in the totals 645 // and accuracy arrays to the current values held by the statistics. Each 646 // array should be of length len. 647 // Returns true if there are more stats available. 648 virtual bool copy_allocation_context_stats(const jint* contexts, 649 jlong* totals, 650 jbyte* accuracy, 651 jint len) { 652 return false; 653 } 654 655 /////////////// Unit tests /////////////// 656 657 NOT_PRODUCT(static void test_is_in();) 658 }; 659 660 // Class to set and reset the GC cause for a CollectedHeap. 661 662 class GCCauseSetter : StackObj { 663 CollectedHeap* _heap; 664 GCCause::Cause _previous_cause; 665 public: 666 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 667 assert(SafepointSynchronize::is_at_safepoint(), 668 "This method manipulates heap state without locking"); 669 _heap = heap; 670 _previous_cause = _heap->gc_cause(); 671 _heap->set_gc_cause(cause); 672 } 673 674 ~GCCauseSetter() { 675 assert(SafepointSynchronize::is_at_safepoint(), 676 "This method manipulates heap state without locking"); 677 _heap->set_gc_cause(_previous_cause); 678 } 679 }; 680 681 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP