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