1 /* 2 * Copyright (c) 2001, 2016, 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_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/events.hpp" 35 36 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This 37 // is an abstract class: there may be many different kinds of heaps. This 38 // class defines the functions that a heap must implement, and contains 39 // infrastructure common to all heaps. 40 41 class AdaptiveSizePolicy; 42 class BarrierSet; 43 class CollectorPolicy; 44 class GCHeapSummary; 45 class GCTimer; 46 class GCTracer; 47 class MetaspaceSummary; 48 class Thread; 49 class ThreadClosure; 50 class VirtualSpaceSummary; 51 class nmethod; 52 53 class GCMessage : public FormatBuffer<1024> { 54 public: 55 bool is_before; 56 57 public: 58 GCMessage() {} 59 }; 60 61 class CollectedHeap; 62 63 class GCHeapLog : public EventLogBase<GCMessage> { 64 private: 65 void log_heap(CollectedHeap* heap, bool before); 66 67 public: 68 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {} 69 70 void log_heap_before(CollectedHeap* heap) { 71 log_heap(heap, true); 72 } 73 void log_heap_after(CollectedHeap* heap) { 74 log_heap(heap, false); 75 } 76 }; 77 78 // 79 // CollectedHeap 80 // GenCollectedHeap 81 // G1CollectedHeap 82 // ParallelScavengeHeap 83 // 84 class CollectedHeap : public CHeapObj<mtInternal> { 85 friend class VMStructs; 86 friend class JVMCIVMStructs; 87 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 88 89 private: 90 #ifdef ASSERT 91 static int _fire_out_of_memory_count; 92 #endif 93 94 GCHeapLog* _gc_heap_log; 95 96 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 97 // or INCLUDE_JVMCI is being used 98 bool _defer_initial_card_mark; 99 100 MemRegion _reserved; 101 102 protected: 103 BarrierSet* _barrier_set; 104 bool _is_gc_active; 105 106 // Used for filler objects (static, but initialized in ctor). 107 static size_t _filler_array_max_size; 108 109 unsigned int _total_collections; // ... started 110 unsigned int _total_full_collections; // ... started 111 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 112 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 113 114 // Reason for current garbage collection. Should be set to 115 // a value reflecting no collection between collections. 116 GCCause::Cause _gc_cause; 117 GCCause::Cause _gc_lastcause; 118 PerfStringVariable* _perf_gc_cause; 119 PerfStringVariable* _perf_gc_lastcause; 120 121 // Constructor 122 CollectedHeap(); 123 124 // Do common initializations that must follow instance construction, 125 // for example, those needing virtual calls. 126 // This code could perhaps be moved into initialize() but would 127 // be slightly more awkward because we want the latter to be a 128 // pure virtual. 129 void pre_initialize(); 130 131 // Create a new tlab. All TLAB allocations must go through this. 132 virtual HeapWord* allocate_new_tlab(size_t size); 133 134 // Accumulate statistics on all tlabs. 135 virtual void accumulate_statistics_all_tlabs(); 136 137 // Reinitialize tlabs before resuming mutators. 138 virtual void resize_all_tlabs(); 139 140 // Allocate from the current thread's TLAB, with broken-out slow path. 141 inline static HeapWord* allocate_from_tlab(KlassHandle klass, Thread* thread, size_t size); 142 static HeapWord* allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size); 143 144 // Allocate an uninitialized block of the given size, or returns NULL if 145 // this is impossible. 146 inline static HeapWord* common_mem_allocate_noinit(KlassHandle klass, size_t size, TRAPS); 147 148 // Like allocate_init, but the block returned by a successful allocation 149 // is guaranteed initialized to zeros. 150 inline static HeapWord* common_mem_allocate_init(KlassHandle klass, size_t size, TRAPS); 151 152 // Helper functions for (VM) allocation. 153 inline static void post_allocation_setup_common(KlassHandle klass, HeapWord* obj); 154 inline static void post_allocation_setup_no_klass_install(KlassHandle klass, 155 HeapWord* objPtr); 156 157 inline static void post_allocation_setup_obj(KlassHandle klass, HeapWord* obj, int size); 158 159 inline static void post_allocation_setup_array(KlassHandle klass, 160 HeapWord* obj, int length); 161 162 inline static void post_allocation_setup_class(KlassHandle klass, HeapWord* obj, int size); 163 164 // Clears an allocated object. 165 inline static void init_obj(HeapWord* obj, size_t size); 166 167 // Filler object utilities. 168 static inline size_t filler_array_hdr_size(); 169 static inline size_t filler_array_min_size(); 170 171 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 172 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 173 174 // Fill with a single array; caller must ensure filler_array_min_size() <= 175 // words <= filler_array_max_size(). 176 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 177 178 // Fill with a single object (either an int array or a java.lang.Object). 179 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 180 181 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer); 182 183 // Verification functions 184 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) 185 PRODUCT_RETURN; 186 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 187 PRODUCT_RETURN; 188 debug_only(static void check_for_valid_allocation_state();) 189 190 public: 191 enum Name { 192 GenCollectedHeap, 193 ParallelScavengeHeap, 194 G1CollectedHeap 195 }; 196 197 static inline size_t filler_array_max_size() { 198 return _filler_array_max_size; 199 } 200 201 virtual Name kind() const = 0; 202 203 virtual const char* name() const = 0; 204 205 /** 206 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 207 * and JNI_OK on success. 208 */ 209 virtual jint initialize() = 0; 210 211 // In many heaps, there will be a need to perform some initialization activities 212 // after the Universe is fully formed, but before general heap allocation is allowed. 213 // This is the correct place to place such initialization methods. 214 virtual void post_initialize() = 0; 215 216 // Stop any onging concurrent work and prepare for exit. 217 virtual void stop() {} 218 219 void initialize_reserved_region(HeapWord *start, HeapWord *end); 220 MemRegion reserved_region() const { return _reserved; } 221 address base() const { return (address)reserved_region().start(); } 222 223 virtual size_t capacity() const = 0; 224 virtual size_t used() const = 0; 225 226 // Return "true" if the part of the heap that allocates Java 227 // objects has reached the maximal committed limit that it can 228 // reach, without a garbage collection. 229 virtual bool is_maximal_no_gc() const = 0; 230 231 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of 232 // memory that the vm could make available for storing 'normal' java objects. 233 // This is based on the reserved address space, but should not include space 234 // that the vm uses internally for bookkeeping or temporary storage 235 // (e.g., in the case of the young gen, one of the survivor 236 // spaces). 237 virtual size_t max_capacity() const = 0; 238 239 // Returns "TRUE" if "p" points into the reserved area of the heap. 240 bool is_in_reserved(const void* p) const { 241 return _reserved.contains(p); 242 } 243 244 bool is_in_reserved_or_null(const void* p) const { 245 return p == NULL || is_in_reserved(p); 246 } 247 248 // Returns "TRUE" iff "p" points into the committed areas of the heap. 249 // This method can be expensive so avoid using it in performance critical 250 // code. 251 virtual bool is_in(const void* p) const = 0; 252 253 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); }) 254 255 // Let's define some terms: a "closed" subset of a heap is one that 256 // 257 // 1) contains all currently-allocated objects, and 258 // 259 // 2) is closed under reference: no object in the closed subset 260 // references one outside the closed subset. 261 // 262 // Membership in a heap's closed subset is useful for assertions. 263 // Clearly, the entire heap is a closed subset, so the default 264 // implementation is to use "is_in_reserved". But this may not be too 265 // liberal to perform useful checking. Also, the "is_in" predicate 266 // defines a closed subset, but may be too expensive, since "is_in" 267 // verifies that its argument points to an object head. The 268 // "closed_subset" method allows a heap to define an intermediate 269 // predicate, allowing more precise checking than "is_in_reserved" at 270 // lower cost than "is_in." 271 272 // One important case is a heap composed of disjoint contiguous spaces, 273 // such as the Garbage-First collector. Such heaps have a convenient 274 // closed subset consisting of the allocated portions of those 275 // contiguous spaces. 276 277 // Return "TRUE" iff the given pointer points into the heap's defined 278 // closed subset (which defaults to the entire heap). 279 virtual bool is_in_closed_subset(const void* p) const { 280 return is_in_reserved(p); 281 } 282 283 bool is_in_closed_subset_or_null(const void* p) const { 284 return p == NULL || is_in_closed_subset(p); 285 } 286 287 // An object is scavengable if its location may move during a scavenge. 288 // (A scavenge is a GC which is not a full GC.) 289 virtual bool is_scavengable(const void *p) = 0; 290 291 void set_gc_cause(GCCause::Cause v) { 292 if (UsePerfData) { 293 _gc_lastcause = _gc_cause; 294 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 295 _perf_gc_cause->set_value(GCCause::to_string(v)); 296 } 297 _gc_cause = v; 298 } 299 GCCause::Cause gc_cause() { return _gc_cause; } 300 301 // General obj/array allocation facilities. 302 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS); 303 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS); 304 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS); 305 inline static oop class_allocate(KlassHandle klass, int size, TRAPS); 306 307 inline static void post_allocation_install_obj_klass(KlassHandle klass, 308 oop obj); 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** 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 AdaptiveSizePolicy for the heap. 483 virtual AdaptiveSizePolicy* size_policy() = 0; 484 485 // Return the CollectorPolicy for the heap 486 virtual CollectorPolicy* collector_policy() const = 0; 487 488 // Iterate over all objects, calling "cl.do_object" on each. 489 virtual void object_iterate(ObjectClosure* cl) = 0; 490 491 // Similar to object_iterate() except iterates only 492 // over live objects. 493 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 494 495 // NOTE! There is no requirement that a collector implement these 496 // functions. 497 // 498 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 499 // each address in the (reserved) heap is a member of exactly 500 // one block. The defining characteristic of a block is that it is 501 // possible to find its size, and thus to progress forward to the next 502 // block. (Blocks may be of different sizes.) Thus, blocks may 503 // represent Java objects, or they might be free blocks in a 504 // free-list-based heap (or subheap), as long as the two kinds are 505 // distinguishable and the size of each is determinable. 506 507 // Returns the address of the start of the "block" that contains the 508 // address "addr". We say "blocks" instead of "object" since some heaps 509 // may not pack objects densely; a chunk may either be an object or a 510 // non-object. 511 virtual HeapWord* block_start(const void* addr) const = 0; 512 513 // Requires "addr" to be the start of a chunk, and returns its size. 514 // "addr + size" is required to be the start of a new chunk, or the end 515 // of the active area of the heap. 516 virtual size_t block_size(const HeapWord* addr) const = 0; 517 518 // Requires "addr" to be the start of a block, and returns "TRUE" iff 519 // the block is an object. 520 virtual bool block_is_obj(const HeapWord* addr) const = 0; 521 522 // Returns the longest time (in ms) that has elapsed since the last 523 // time that any part of the heap was examined by a garbage collection. 524 virtual jlong millis_since_last_gc() = 0; 525 526 // Perform any cleanup actions necessary before allowing a verification. 527 virtual void prepare_for_verify() = 0; 528 529 // Generate any dumps preceding or following a full gc 530 private: 531 void full_gc_dump(GCTimer* timer, bool before); 532 public: 533 void pre_full_gc_dump(GCTimer* timer); 534 void post_full_gc_dump(GCTimer* timer); 535 536 VirtualSpaceSummary create_heap_space_summary(); 537 GCHeapSummary create_heap_summary(); 538 539 MetaspaceSummary create_metaspace_summary(); 540 541 // Print heap information on the given outputStream. 542 virtual void print_on(outputStream* st) const = 0; 543 // The default behavior is to call print_on() on tty. 544 virtual void print() const { 545 print_on(tty); 546 } 547 // Print more detailed heap information on the given 548 // outputStream. The default behavior is to call print_on(). It is 549 // up to each subclass to override it and add any additional output 550 // it needs. 551 virtual void print_extended_on(outputStream* st) const { 552 print_on(st); 553 } 554 555 virtual void print_on_error(outputStream* st) const; 556 557 // Print all GC threads (other than the VM thread) 558 // used by this heap. 559 virtual void print_gc_threads_on(outputStream* st) const = 0; 560 // The default behavior is to call print_gc_threads_on() on tty. 561 void print_gc_threads() { 562 print_gc_threads_on(tty); 563 } 564 // Iterator for all GC threads (other than VM thread) 565 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 566 567 // Print any relevant tracing info that flags imply. 568 // Default implementation does nothing. 569 virtual void print_tracing_info() const = 0; 570 571 void print_heap_before_gc(); 572 void print_heap_after_gc(); 573 574 // Registering and unregistering an nmethod (compiled code) with the heap. 575 // Override with specific mechanism for each specialized heap type. 576 virtual void register_nmethod(nmethod* nm); 577 virtual void unregister_nmethod(nmethod* nm); 578 579 void trace_heap_before_gc(const GCTracer* gc_tracer); 580 void trace_heap_after_gc(const GCTracer* gc_tracer); 581 582 // Heap verification 583 virtual void verify(VerifyOption option) = 0; 584 585 // Non product verification and debugging. 586 #ifndef PRODUCT 587 // Support for PromotionFailureALot. Return true if it's time to cause a 588 // promotion failure. The no-argument version uses 589 // this->_promotion_failure_alot_count as the counter. 590 inline bool promotion_should_fail(volatile size_t* count); 591 inline bool promotion_should_fail(); 592 593 // Reset the PromotionFailureALot counters. Should be called at the end of a 594 // GC in which promotion failure occurred. 595 inline void reset_promotion_should_fail(volatile size_t* count); 596 inline void reset_promotion_should_fail(); 597 #endif // #ifndef PRODUCT 598 599 #ifdef ASSERT 600 static int fired_fake_oom() { 601 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 602 } 603 #endif 604 605 public: 606 // Copy the current allocation context statistics for the specified contexts. 607 // For each context in contexts, set the corresponding entries in the totals 608 // and accuracy arrays to the current values held by the statistics. Each 609 // array should be of length len. 610 // Returns true if there are more stats available. 611 virtual bool copy_allocation_context_stats(const jint* contexts, 612 jlong* totals, 613 jbyte* accuracy, 614 jint len) { 615 return false; 616 } 617 618 /////////////// Unit tests /////////////// 619 620 NOT_PRODUCT(static void test_is_in();) 621 }; 622 623 // Class to set and reset the GC cause for a CollectedHeap. 624 625 class GCCauseSetter : StackObj { 626 CollectedHeap* _heap; 627 GCCause::Cause _previous_cause; 628 public: 629 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 630 assert(SafepointSynchronize::is_at_safepoint(), 631 "This method manipulates heap state without locking"); 632 _heap = heap; 633 _previous_cause = _heap->gc_cause(); 634 _heap->set_gc_cause(cause); 635 } 636 637 ~GCCauseSetter() { 638 assert(SafepointSynchronize::is_at_safepoint(), 639 "This method manipulates heap state without locking"); 640 _heap->set_gc_cause(_previous_cause); 641 } 642 }; 643 644 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP