1 /* 2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 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 #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); 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 }; 193 194 static inline size_t filler_array_max_size() { 195 return _filler_array_max_size; 196 } 197 198 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; } 199 200 /** 201 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 202 * and JNI_OK on success. 203 */ 204 virtual jint initialize() = 0; 205 206 // In many heaps, there will be a need to perform some initialization activities 207 // after the Universe is fully formed, but before general heap allocation is allowed. 208 // This is the correct place to place such initialization methods. 209 virtual void post_initialize() = 0; 210 211 MemRegion reserved_region() const { return _reserved; } 212 address base() const { return (address)reserved_region().start(); } 213 214 virtual size_t capacity() const = 0; 215 virtual size_t used() const = 0; 216 217 // Return "true" if the part of the heap that allocates Java 218 // objects has reached the maximal committed limit that it can 219 // reach, without a garbage collection. 220 virtual bool is_maximal_no_gc() const = 0; 221 222 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 223 // memory that the vm could make available for storing 'normal' java objects. 224 // This is based on the reserved address space, but should not include space 225 // that the vm uses internally for bookkeeping or temporary storage 226 // (e.g., in the case of the young gen, one of the survivor 227 // spaces). 228 virtual size_t max_capacity() const = 0; 229 230 // Returns "TRUE" if "p" points into the reserved area of the heap. 231 bool is_in_reserved(const void* p) const { 232 return _reserved.contains(p); 233 } 234 235 bool is_in_reserved_or_null(const void* p) const { 236 return p == NULL || is_in_reserved(p); 237 } 238 239 // Returns "TRUE" iff "p" points into the committed areas of the heap. 240 // Since this method can be expensive in general, we restrict its 241 // use to assertion checking only. 242 virtual bool is_in(const void* p) const = 0; 243 244 bool is_in_or_null(const void* p) const { 245 return p == NULL || is_in(p); 246 } 247 248 bool is_in_place(Metadata** p) { 249 return !Universe::heap()->is_in(p); 250 } 251 bool is_in_place(oop* p) { return Universe::heap()->is_in(p); } 252 bool is_in_place(narrowOop* p) { 253 oop o = oopDesc::load_decode_heap_oop_not_null(p); 254 return Universe::heap()->is_in((const void*)o); 255 } 256 257 // Let's define some terms: a "closed" subset of a heap is one that 258 // 259 // 1) contains all currently-allocated objects, and 260 // 261 // 2) is closed under reference: no object in the closed subset 262 // references one outside the closed subset. 263 // 264 // Membership in a heap's closed subset is useful for assertions. 265 // Clearly, the entire heap is a closed subset, so the default 266 // implementation is to use "is_in_reserved". But this may not be too 267 // liberal to perform useful checking. Also, the "is_in" predicate 268 // defines a closed subset, but may be too expensive, since "is_in" 269 // verifies that its argument points to an object head. The 270 // "closed_subset" method allows a heap to define an intermediate 271 // predicate, allowing more precise checking than "is_in_reserved" at 272 // lower cost than "is_in." 273 274 // One important case is a heap composed of disjoint contiguous spaces, 275 // such as the Garbage-First collector. Such heaps have a convenient 276 // closed subset consisting of the allocated portions of those 277 // contiguous spaces. 278 279 // Return "TRUE" iff the given pointer points into the heap's defined 280 // closed subset (which defaults to the entire heap). 281 virtual bool is_in_closed_subset(const void* p) const { 282 return is_in_reserved(p); 283 } 284 285 bool is_in_closed_subset_or_null(const void* p) const { 286 return p == NULL || is_in_closed_subset(p); 287 } 288 289 #ifdef ASSERT 290 // Returns true if "p" is in the part of the 291 // heap being collected. 292 virtual bool is_in_partial_collection(const void *p) = 0; 293 #endif 294 295 // An object is scavengable if its location may move during a scavenge. 296 // (A scavenge is a GC which is not a full GC.) 297 virtual bool is_scavengable(const void *p) = 0; 298 299 void set_gc_cause(GCCause::Cause v) { 300 if (UsePerfData) { 301 _gc_lastcause = _gc_cause; 302 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 303 _perf_gc_cause->set_value(GCCause::to_string(v)); 304 } 305 _gc_cause = v; 306 } 307 GCCause::Cause gc_cause() { return _gc_cause; } 308 309 // Number of threads currently working on GC tasks. 310 uint n_par_threads() { return _n_par_threads; } 311 312 // May be overridden to set additional parallelism. 313 virtual void set_par_threads(uint t) { _n_par_threads = t; }; 314 315 // Allocate and initialize instances of Class 316 static oop Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS); 317 318 // General obj/array allocation facilities. 319 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS); 320 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS); 321 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS); 322 323 inline static void post_allocation_install_obj_klass(KlassHandle klass, 324 oop obj); 325 326 // Raw memory allocation facilities 327 // The obj and array allocate methods are covers for these methods. 328 // mem_allocate() should never be 329 // called to allocate TLABs, only individual objects. 330 virtual HeapWord* mem_allocate(size_t size, 331 bool* gc_overhead_limit_was_exceeded) = 0; 332 333 // Utilities for turning raw memory into filler objects. 334 // 335 // min_fill_size() is the smallest region that can be filled. 336 // fill_with_objects() can fill arbitrary-sized regions of the heap using 337 // multiple objects. fill_with_object() is for regions known to be smaller 338 // than the largest array of integers; it uses a single object to fill the 339 // region and has slightly less overhead. 340 static size_t min_fill_size() { 341 return size_t(align_object_size(oopDesc::header_size())); 342 } 343 344 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 345 346 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 347 static void fill_with_object(MemRegion region, bool zap = true) { 348 fill_with_object(region.start(), region.word_size(), zap); 349 } 350 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 351 fill_with_object(start, pointer_delta(end, start), zap); 352 } 353 354 // Some heaps may offer a contiguous region for shared non-blocking 355 // allocation, via inlined code (by exporting the address of the top and 356 // end fields defining the extent of the contiguous allocation region.) 357 358 // This function returns "true" iff the heap supports this kind of 359 // allocation. (Default is "no".) 360 virtual bool supports_inline_contig_alloc() const { 361 return false; 362 } 363 // These functions return the addresses of the fields that define the 364 // boundaries of the contiguous allocation area. (These fields should be 365 // physically near to one another.) 366 virtual HeapWord** top_addr() const { 367 guarantee(false, "inline contiguous allocation not supported"); 368 return NULL; 369 } 370 virtual HeapWord** end_addr() const { 371 guarantee(false, "inline contiguous allocation not supported"); 372 return NULL; 373 } 374 375 // Some heaps may be in an unparseable state at certain times between 376 // collections. This may be necessary for efficient implementation of 377 // certain allocation-related activities. Calling this function before 378 // attempting to parse a heap ensures that the heap is in a parsable 379 // state (provided other concurrent activity does not introduce 380 // unparsability). It is normally expected, therefore, that this 381 // method is invoked with the world stopped. 382 // NOTE: if you override this method, make sure you call 383 // super::ensure_parsability so that the non-generational 384 // part of the work gets done. See implementation of 385 // CollectedHeap::ensure_parsability and, for instance, 386 // that of GenCollectedHeap::ensure_parsability(). 387 // The argument "retire_tlabs" controls whether existing TLABs 388 // are merely filled or also retired, thus preventing further 389 // allocation from them and necessitating allocation of new TLABs. 390 virtual void ensure_parsability(bool retire_tlabs); 391 392 // Return an estimate of the maximum allocation that could be performed 393 // without triggering any collection or expansion activity. In a 394 // generational collector, for example, this is probably the largest 395 // allocation that could be supported (without expansion) in the youngest 396 // generation. It is "unsafe" because no locks are taken; the result 397 // should be treated as an approximation, not a guarantee, for use in 398 // heuristic resizing decisions. 399 virtual size_t unsafe_max_alloc() = 0; 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 { 407 return false; 408 } 409 // The amount of space available for thread-local allocation buffers. 410 virtual size_t tlab_capacity(Thread *thr) const { 411 guarantee(false, "thread-local allocation buffers not supported"); 412 return 0; 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 // Callback from VM_CollectForMetadataAllocation operation. 479 MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 480 size_t size, 481 Metaspace::MetadataType mdtype); 482 483 // Returns the barrier set for this heap 484 BarrierSet* barrier_set() { return _barrier_set; } 485 486 // Returns "true" iff there is a stop-world GC in progress. (I assume 487 // that it should answer "false" for the concurrent part of a concurrent 488 // collector -- dld). 489 bool is_gc_active() const { return _is_gc_active; } 490 491 // Total number of GC collections (started) 492 unsigned int total_collections() const { return _total_collections; } 493 unsigned int total_full_collections() const { return _total_full_collections;} 494 495 // Increment total number of GC collections (started) 496 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 497 void increment_total_collections(bool full = false) { 498 _total_collections++; 499 if (full) { 500 increment_total_full_collections(); 501 } 502 } 503 504 void increment_total_full_collections() { _total_full_collections++; } 505 506 // Return the AdaptiveSizePolicy for the heap. 507 virtual AdaptiveSizePolicy* size_policy() = 0; 508 509 // Return the CollectorPolicy for the heap 510 virtual CollectorPolicy* collector_policy() const = 0; 511 512 void oop_iterate_no_header(OopClosure* cl); 513 514 // Iterate over all the ref-containing fields of all objects, calling 515 // "cl.do_oop" on each. 516 virtual void oop_iterate(ExtendedOopClosure* cl) = 0; 517 518 // Iterate over all objects, calling "cl.do_object" on each. 519 virtual void object_iterate(ObjectClosure* cl) = 0; 520 521 // Similar to object_iterate() except iterates only 522 // over live objects. 523 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 524 525 // NOTE! There is no requirement that a collector implement these 526 // functions. 527 // 528 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 529 // each address in the (reserved) heap is a member of exactly 530 // one block. The defining characteristic of a block is that it is 531 // possible to find its size, and thus to progress forward to the next 532 // block. (Blocks may be of different sizes.) Thus, blocks may 533 // represent Java objects, or they might be free blocks in a 534 // free-list-based heap (or subheap), as long as the two kinds are 535 // distinguishable and the size of each is determinable. 536 537 // Returns the address of the start of the "block" that contains the 538 // address "addr". We say "blocks" instead of "object" since some heaps 539 // may not pack objects densely; a chunk may either be an object or a 540 // non-object. 541 virtual HeapWord* block_start(const void* addr) const = 0; 542 543 // Requires "addr" to be the start of a chunk, and returns its size. 544 // "addr + size" is required to be the start of a new chunk, or the end 545 // of the active area of the heap. 546 virtual size_t block_size(const HeapWord* addr) const = 0; 547 548 // Requires "addr" to be the start of a block, and returns "TRUE" iff 549 // the block is an object. 550 virtual bool block_is_obj(const HeapWord* addr) const = 0; 551 552 // Returns the longest time (in ms) that has elapsed since the last 553 // time that any part of the heap was examined by a garbage collection. 554 virtual jlong millis_since_last_gc() = 0; 555 556 // Perform any cleanup actions necessary before allowing a verification. 557 virtual void prepare_for_verify() = 0; 558 559 // Generate any dumps preceding or following a full gc 560 void pre_full_gc_dump(GCTimer* timer); 561 void post_full_gc_dump(GCTimer* timer); 562 563 VirtualSpaceSummary create_heap_space_summary(); 564 GCHeapSummary create_heap_summary(); 565 566 MetaspaceSummary create_metaspace_summary(); 567 568 // Print heap information on the given outputStream. 569 virtual void print_on(outputStream* st) const = 0; 570 // The default behavior is to call print_on() on tty. 571 virtual void print() const { 572 print_on(tty); 573 } 574 // Print more detailed heap information on the given 575 // outputStream. The default behavior is to call print_on(). It is 576 // up to each subclass to override it and add any additional output 577 // it needs. 578 virtual void print_extended_on(outputStream* st) const { 579 print_on(st); 580 } 581 582 virtual void print_on_error(outputStream* st) const { 583 st->print_cr("Heap:"); 584 print_extended_on(st); 585 st->cr(); 586 587 _barrier_set->print_on(st); 588 } 589 590 // Print all GC threads (other than the VM thread) 591 // used by this heap. 592 virtual void print_gc_threads_on(outputStream* st) const = 0; 593 // The default behavior is to call print_gc_threads_on() on tty. 594 void print_gc_threads() { 595 print_gc_threads_on(tty); 596 } 597 // Iterator for all GC threads (other than VM thread) 598 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 599 600 // Print any relevant tracing info that flags imply. 601 // Default implementation does nothing. 602 virtual void print_tracing_info() const = 0; 603 604 void print_heap_before_gc(); 605 void print_heap_after_gc(); 606 607 // Registering and unregistering an nmethod (compiled code) with the heap. 608 // Override with specific mechanism for each specialized heap type. 609 virtual void register_nmethod(nmethod* nm); 610 virtual void unregister_nmethod(nmethod* nm); 611 612 void trace_heap_before_gc(GCTracer* gc_tracer); 613 void trace_heap_after_gc(GCTracer* gc_tracer); 614 615 // Heap verification 616 virtual void verify(bool silent, VerifyOption option) = 0; 617 618 // Non product verification and debugging. 619 #ifndef PRODUCT 620 // Support for PromotionFailureALot. Return true if it's time to cause a 621 // promotion failure. The no-argument version uses 622 // this->_promotion_failure_alot_count as the counter. 623 inline bool promotion_should_fail(volatile size_t* count); 624 inline bool promotion_should_fail(); 625 626 // Reset the PromotionFailureALot counters. Should be called at the end of a 627 // GC in which promotion failure occurred. 628 inline void reset_promotion_should_fail(volatile size_t* count); 629 inline void reset_promotion_should_fail(); 630 #endif // #ifndef PRODUCT 631 632 #ifdef ASSERT 633 static int fired_fake_oom() { 634 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 635 } 636 #endif 637 638 public: 639 // This is a convenience method that is used in cases where 640 // the actual number of GC worker threads is not pertinent but 641 // only whether there more than 0. Use of this method helps 642 // reduce the occurrence of ParallelGCThreads to uses where the 643 // actual number may be germane. 644 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; } 645 646 /////////////// Unit tests /////////////// 647 648 NOT_PRODUCT(static void test_is_in();) 649 }; 650 651 // Class to set and reset the GC cause for a CollectedHeap. 652 653 class GCCauseSetter : StackObj { 654 CollectedHeap* _heap; 655 GCCause::Cause _previous_cause; 656 public: 657 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 658 assert(SafepointSynchronize::is_at_safepoint(), 659 "This method manipulates heap state without locking"); 660 _heap = heap; 661 _previous_cause = _heap->gc_cause(); 662 _heap->set_gc_cause(cause); 663 } 664 665 ~GCCauseSetter() { 666 assert(SafepointSynchronize::is_at_safepoint(), 667 "This method manipulates heap state without locking"); 668 _heap->set_gc_cause(_previous_cause); 669 } 670 }; 671 672 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP