1 /* 2 * Copyright (c) 2001, 2012, 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 "memory/allocation.hpp" 30 #include "memory/barrierSet.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 BarrierSet; 42 class ThreadClosure; 43 class AdaptiveSizePolicy; 44 class Thread; 45 class CollectorPolicy; 46 47 class GCMessage : public FormatBuffer<1024> { 48 public: 49 bool is_before; 50 51 public: 52 GCMessage() {} 53 }; 54 55 class GCHeapLog : public EventLogBase<GCMessage> { 56 private: 57 void log_heap(bool before); 58 59 public: 60 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {} 61 62 void log_heap_before() { 63 log_heap(true); 64 } 65 void log_heap_after() { 66 log_heap(false); 67 } 68 }; 69 70 // 71 // CollectedHeap 72 // SharedHeap 73 // GenCollectedHeap 74 // G1CollectedHeap 75 // ParallelScavengeHeap 76 // 77 class CollectedHeap : public CHeapObj { 78 friend class VMStructs; 79 friend class IsGCActiveMark; // Block structured external access to _is_gc_active 80 friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe 81 82 #ifdef ASSERT 83 static int _fire_out_of_memory_count; 84 #endif 85 86 // Used for filler objects (static, but initialized in ctor). 87 static size_t _filler_array_max_size; 88 89 GCHeapLog* _gc_heap_log; 90 91 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used 92 bool _defer_initial_card_mark; 93 94 protected: 95 MemRegion _reserved; 96 BarrierSet* _barrier_set; 97 bool _is_gc_active; 98 uint _n_par_threads; 99 100 unsigned int _total_collections; // ... started 101 unsigned int _total_full_collections; // ... started 102 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;) 103 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;) 104 105 // Reason for current garbage collection. Should be set to 106 // a value reflecting no collection between collections. 107 GCCause::Cause _gc_cause; 108 GCCause::Cause _gc_lastcause; 109 PerfStringVariable* _perf_gc_cause; 110 PerfStringVariable* _perf_gc_lastcause; 111 112 // Constructor 113 CollectedHeap(); 114 115 // Do common initializations that must follow instance construction, 116 // for example, those needing virtual calls. 117 // This code could perhaps be moved into initialize() but would 118 // be slightly more awkward because we want the latter to be a 119 // pure virtual. 120 void pre_initialize(); 121 122 // Create a new tlab. All TLAB allocations must go through this. 123 virtual HeapWord* allocate_new_tlab(size_t size); 124 125 // Accumulate statistics on all tlabs. 126 virtual void accumulate_statistics_all_tlabs(); 127 128 // Reinitialize tlabs before resuming mutators. 129 virtual void resize_all_tlabs(); 130 131 // Allocate from the current thread's TLAB, with broken-out slow path. 132 inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size); 133 static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size); 134 135 // Allocate an uninitialized block of the given size, or returns NULL if 136 // this is impossible. 137 inline static HeapWord* common_mem_allocate_noinit(size_t size, TRAPS); 138 139 // Like allocate_init, but the block returned by a successful allocation 140 // is guaranteed initialized to zeros. 141 inline static HeapWord* common_mem_allocate_init(size_t size, TRAPS); 142 143 // Same as common_mem version, except memory is allocated in the permanent area 144 // If there is no permanent area, revert to common_mem_allocate_noinit 145 inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS); 146 147 // Same as common_mem version, except memory is allocated in the permanent area 148 // If there is no permanent area, revert to common_mem_allocate_init 149 inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS); 150 151 // Helper functions for (VM) allocation. 152 inline static void post_allocation_setup_common(KlassHandle klass, 153 HeapWord* obj, size_t size); 154 inline static void post_allocation_setup_no_klass_install(KlassHandle klass, 155 HeapWord* objPtr, 156 size_t size); 157 158 inline static void post_allocation_setup_obj(KlassHandle klass, 159 HeapWord* obj, size_t size); 160 161 inline static void post_allocation_setup_array(KlassHandle klass, 162 HeapWord* obj, size_t size, 163 int length); 164 165 // Clears an allocated object. 166 inline static void init_obj(HeapWord* obj, size_t size); 167 168 // Filler object utilities. 169 static inline size_t filler_array_hdr_size(); 170 static inline size_t filler_array_min_size(); 171 172 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);) 173 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);) 174 175 // Fill with a single array; caller must ensure filler_array_min_size() <= 176 // words <= filler_array_max_size(). 177 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true); 178 179 // Fill with a single object (either an int array or a java.lang.Object). 180 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true); 181 182 // Verification functions 183 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size) 184 PRODUCT_RETURN; 185 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) 186 PRODUCT_RETURN; 187 debug_only(static void check_for_valid_allocation_state();) 188 189 public: 190 enum Name { 191 Abstract, 192 SharedHeap, 193 GenCollectedHeap, 194 ParallelScavengeHeap, 195 G1CollectedHeap 196 }; 197 198 static inline size_t filler_array_max_size() { 199 return _filler_array_max_size; 200 } 201 202 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; } 203 204 /** 205 * Returns JNI error code JNI_ENOMEM if memory could not be allocated, 206 * and JNI_OK on success. 207 */ 208 virtual jint initialize() = 0; 209 210 // In many heaps, there will be a need to perform some initialization activities 211 // after the Universe is fully formed, but before general heap allocation is allowed. 212 // This is the correct place to place such initialization methods. 213 virtual void post_initialize() = 0; 214 215 MemRegion reserved_region() const { return _reserved; } 216 address base() const { return (address)reserved_region().start(); } 217 218 // Future cleanup here. The following functions should specify bytes or 219 // heapwords as part of their signature. 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 virtual size_t permanent_capacity() const = 0; 229 virtual size_t permanent_used() 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 (e.g., 235 // perm gen space or, 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 // Since this method can be expensive in general, we restrict its 250 // use to assertion checking only. 251 virtual bool is_in(const void* p) const = 0; 252 253 bool is_in_or_null(const void* p) const { 254 return p == NULL || is_in(p); 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 // XXX is_permanent() and is_in_permanent() should be better named 290 // to distinguish one from the other. 291 292 // Returns "TRUE" if "p" is allocated as "permanent" data. 293 // If the heap does not use "permanent" data, returns the same 294 // value is_in_reserved() would return. 295 // NOTE: this actually returns true if "p" is in reserved space 296 // for the space not that it is actually allocated (i.e. in committed 297 // space). If you need the more conservative answer use is_permanent(). 298 virtual bool is_in_permanent(const void *p) const = 0; 299 300 301 #ifdef ASSERT 302 // Returns true if "p" is in the part of the 303 // heap being collected. 304 virtual bool is_in_partial_collection(const void *p) = 0; 305 #endif 306 307 bool is_in_permanent_or_null(const void *p) const { 308 return p == NULL || is_in_permanent(p); 309 } 310 311 // Returns "TRUE" if "p" is in the committed area of "permanent" data. 312 // If the heap does not use "permanent" data, returns the same 313 // value is_in() would return. 314 virtual bool is_permanent(const void *p) const = 0; 315 316 bool is_permanent_or_null(const void *p) const { 317 return p == NULL || is_permanent(p); 318 } 319 320 // An object is scavengable if its location may move during a scavenge. 321 // (A scavenge is a GC which is not a full GC.) 322 virtual bool is_scavengable(const void *p) = 0; 323 324 // Returns "TRUE" if "p" is a method oop in the 325 // current heap, with high probability. This predicate 326 // is not stable, in general. 327 bool is_valid_method(oop p) const; 328 329 void set_gc_cause(GCCause::Cause v) { 330 if (UsePerfData) { 331 _gc_lastcause = _gc_cause; 332 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 333 _perf_gc_cause->set_value(GCCause::to_string(v)); 334 } 335 _gc_cause = v; 336 } 337 GCCause::Cause gc_cause() { return _gc_cause; } 338 339 // Number of threads currently working on GC tasks. 340 uint n_par_threads() { return _n_par_threads; } 341 342 // May be overridden to set additional parallelism. 343 virtual void set_par_threads(uint t) { _n_par_threads = t; }; 344 345 // Preload classes into the shared portion of the heap, and then dump 346 // that data to a file so that it can be loaded directly by another 347 // VM (then terminate). 348 virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); } 349 350 // Allocate and initialize instances of Class 351 static oop Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS); 352 353 // General obj/array allocation facilities. 354 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS); 355 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS); 356 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS); 357 358 // Special obj/array allocation facilities. 359 // Some heaps may want to manage "permanent" data uniquely. These default 360 // to the general routines if the heap does not support such handling. 361 inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS); 362 // permanent_obj_allocate_no_klass_install() does not do the installation of 363 // the klass pointer in the newly created object (as permanent_obj_allocate() 364 // above does). This allows for a delay in the installation of the klass 365 // pointer that is needed during the create of klassKlass's. The 366 // method post_allocation_install_obj_klass() is used to install the 367 // klass pointer. 368 inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass, 369 int size, 370 TRAPS); 371 inline static void post_allocation_install_obj_klass(KlassHandle klass, 372 oop obj, 373 int size); 374 inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS); 375 376 // Raw memory allocation facilities 377 // The obj and array allocate methods are covers for these methods. 378 // The permanent allocation method should default to mem_allocate if 379 // permanent memory isn't supported. mem_allocate() should never be 380 // called to allocate TLABs, only individual objects. 381 virtual HeapWord* mem_allocate(size_t size, 382 bool* gc_overhead_limit_was_exceeded) = 0; 383 virtual HeapWord* permanent_mem_allocate(size_t size) = 0; 384 385 // Utilities for turning raw memory into filler objects. 386 // 387 // min_fill_size() is the smallest region that can be filled. 388 // fill_with_objects() can fill arbitrary-sized regions of the heap using 389 // multiple objects. fill_with_object() is for regions known to be smaller 390 // than the largest array of integers; it uses a single object to fill the 391 // region and has slightly less overhead. 392 static size_t min_fill_size() { 393 return size_t(align_object_size(oopDesc::header_size())); 394 } 395 396 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true); 397 398 static void fill_with_object(HeapWord* start, size_t words, bool zap = true); 399 static void fill_with_object(MemRegion region, bool zap = true) { 400 fill_with_object(region.start(), region.word_size(), zap); 401 } 402 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) { 403 fill_with_object(start, pointer_delta(end, start), zap); 404 } 405 406 // Some heaps may offer a contiguous region for shared non-blocking 407 // allocation, via inlined code (by exporting the address of the top and 408 // end fields defining the extent of the contiguous allocation region.) 409 410 // This function returns "true" iff the heap supports this kind of 411 // allocation. (Default is "no".) 412 virtual bool supports_inline_contig_alloc() const { 413 return false; 414 } 415 // These functions return the addresses of the fields that define the 416 // boundaries of the contiguous allocation area. (These fields should be 417 // physically near to one another.) 418 virtual HeapWord** top_addr() const { 419 guarantee(false, "inline contiguous allocation not supported"); 420 return NULL; 421 } 422 virtual HeapWord** end_addr() const { 423 guarantee(false, "inline contiguous allocation not supported"); 424 return NULL; 425 } 426 427 // Some heaps may be in an unparseable state at certain times between 428 // collections. This may be necessary for efficient implementation of 429 // certain allocation-related activities. Calling this function before 430 // attempting to parse a heap ensures that the heap is in a parsable 431 // state (provided other concurrent activity does not introduce 432 // unparsability). It is normally expected, therefore, that this 433 // method is invoked with the world stopped. 434 // NOTE: if you override this method, make sure you call 435 // super::ensure_parsability so that the non-generational 436 // part of the work gets done. See implementation of 437 // CollectedHeap::ensure_parsability and, for instance, 438 // that of GenCollectedHeap::ensure_parsability(). 439 // The argument "retire_tlabs" controls whether existing TLABs 440 // are merely filled or also retired, thus preventing further 441 // allocation from them and necessitating allocation of new TLABs. 442 virtual void ensure_parsability(bool retire_tlabs); 443 444 // Return an estimate of the maximum allocation that could be performed 445 // without triggering any collection or expansion activity. In a 446 // generational collector, for example, this is probably the largest 447 // allocation that could be supported (without expansion) in the youngest 448 // generation. It is "unsafe" because no locks are taken; the result 449 // should be treated as an approximation, not a guarantee, for use in 450 // heuristic resizing decisions. 451 virtual size_t unsafe_max_alloc() = 0; 452 453 // Section on thread-local allocation buffers (TLABs) 454 // If the heap supports thread-local allocation buffers, it should override 455 // the following methods: 456 // Returns "true" iff the heap supports thread-local allocation buffers. 457 // The default is "no". 458 virtual bool supports_tlab_allocation() const { 459 return false; 460 } 461 // The amount of space available for thread-local allocation buffers. 462 virtual size_t tlab_capacity(Thread *thr) const { 463 guarantee(false, "thread-local allocation buffers not supported"); 464 return 0; 465 } 466 // An estimate of the maximum allocation that could be performed 467 // for thread-local allocation buffers without triggering any 468 // collection or expansion activity. 469 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const { 470 guarantee(false, "thread-local allocation buffers not supported"); 471 return 0; 472 } 473 474 // Can a compiler initialize a new object without store barriers? 475 // This permission only extends from the creation of a new object 476 // via a TLAB up to the first subsequent safepoint. If such permission 477 // is granted for this heap type, the compiler promises to call 478 // defer_store_barrier() below on any slow path allocation of 479 // a new object for which such initializing store barriers will 480 // have been elided. 481 virtual bool can_elide_tlab_store_barriers() const = 0; 482 483 // If a compiler is eliding store barriers for TLAB-allocated objects, 484 // there is probably a corresponding slow path which can produce 485 // an object allocated anywhere. The compiler's runtime support 486 // promises to call this function on such a slow-path-allocated 487 // object before performing initializations that have elided 488 // store barriers. Returns new_obj, or maybe a safer copy thereof. 489 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj); 490 491 // Answers whether an initializing store to a new object currently 492 // allocated at the given address doesn't need a store 493 // barrier. Returns "true" if it doesn't need an initializing 494 // store barrier; answers "false" if it does. 495 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0; 496 497 // If a compiler is eliding store barriers for TLAB-allocated objects, 498 // we will be informed of a slow-path allocation by a call 499 // to new_store_pre_barrier() above. Such a call precedes the 500 // initialization of the object itself, and no post-store-barriers will 501 // be issued. Some heap types require that the barrier strictly follows 502 // the initializing stores. (This is currently implemented by deferring the 503 // barrier until the next slow-path allocation or gc-related safepoint.) 504 // This interface answers whether a particular heap type needs the card 505 // mark to be thus strictly sequenced after the stores. 506 virtual bool card_mark_must_follow_store() const = 0; 507 508 // If the CollectedHeap was asked to defer a store barrier above, 509 // this informs it to flush such a deferred store barrier to the 510 // remembered set. 511 virtual void flush_deferred_store_barrier(JavaThread* thread); 512 513 // Can a compiler elide a store barrier when it writes 514 // a permanent oop into the heap? Applies when the compiler 515 // is storing x to the heap, where x->is_perm() is true. 516 virtual bool can_elide_permanent_oop_store_barriers() const = 0; 517 518 // Does this heap support heap inspection (+PrintClassHistogram?) 519 virtual bool supports_heap_inspection() const = 0; 520 521 // Perform a collection of the heap; intended for use in implementing 522 // "System.gc". This probably implies as full a collection as the 523 // "CollectedHeap" supports. 524 virtual void collect(GCCause::Cause cause) = 0; 525 526 // This interface assumes that it's being called by the 527 // vm thread. It collects the heap assuming that the 528 // heap lock is already held and that we are executing in 529 // the context of the vm thread. 530 virtual void collect_as_vm_thread(GCCause::Cause cause) = 0; 531 532 // Returns the barrier set for this heap 533 BarrierSet* barrier_set() { return _barrier_set; } 534 535 // Returns "true" iff there is a stop-world GC in progress. (I assume 536 // that it should answer "false" for the concurrent part of a concurrent 537 // collector -- dld). 538 bool is_gc_active() const { return _is_gc_active; } 539 540 // Total number of GC collections (started) 541 unsigned int total_collections() const { return _total_collections; } 542 unsigned int total_full_collections() const { return _total_full_collections;} 543 544 // Increment total number of GC collections (started) 545 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2 546 void increment_total_collections(bool full = false) { 547 _total_collections++; 548 if (full) { 549 increment_total_full_collections(); 550 } 551 } 552 553 void increment_total_full_collections() { _total_full_collections++; } 554 555 // Return the AdaptiveSizePolicy for the heap. 556 virtual AdaptiveSizePolicy* size_policy() = 0; 557 558 // Return the CollectorPolicy for the heap 559 virtual CollectorPolicy* collector_policy() const = 0; 560 561 // Iterate over all the ref-containing fields of all objects, calling 562 // "cl.do_oop" on each. This includes objects in permanent memory. 563 virtual void oop_iterate(OopClosure* cl) = 0; 564 565 // Iterate over all objects, calling "cl.do_object" on each. 566 // This includes objects in permanent memory. 567 virtual void object_iterate(ObjectClosure* cl) = 0; 568 569 // Similar to object_iterate() except iterates only 570 // over live objects. 571 virtual void safe_object_iterate(ObjectClosure* cl) = 0; 572 573 // Behaves the same as oop_iterate, except only traverses 574 // interior pointers contained in permanent memory. If there 575 // is no permanent memory, does nothing. 576 virtual void permanent_oop_iterate(OopClosure* cl) = 0; 577 578 // Behaves the same as object_iterate, except only traverses 579 // object contained in permanent memory. If there is no 580 // permanent memory, does nothing. 581 virtual void permanent_object_iterate(ObjectClosure* cl) = 0; 582 583 // NOTE! There is no requirement that a collector implement these 584 // functions. 585 // 586 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 587 // each address in the (reserved) heap is a member of exactly 588 // one block. The defining characteristic of a block is that it is 589 // possible to find its size, and thus to progress forward to the next 590 // block. (Blocks may be of different sizes.) Thus, blocks may 591 // represent Java objects, or they might be free blocks in a 592 // free-list-based heap (or subheap), as long as the two kinds are 593 // distinguishable and the size of each is determinable. 594 595 // Returns the address of the start of the "block" that contains the 596 // address "addr". We say "blocks" instead of "object" since some heaps 597 // may not pack objects densely; a chunk may either be an object or a 598 // non-object. 599 virtual HeapWord* block_start(const void* addr) const = 0; 600 601 // Requires "addr" to be the start of a chunk, and returns its size. 602 // "addr + size" is required to be the start of a new chunk, or the end 603 // of the active area of the heap. 604 virtual size_t block_size(const HeapWord* addr) const = 0; 605 606 // Requires "addr" to be the start of a block, and returns "TRUE" iff 607 // the block is an object. 608 virtual bool block_is_obj(const HeapWord* addr) const = 0; 609 610 // Returns the longest time (in ms) that has elapsed since the last 611 // time that any part of the heap was examined by a garbage collection. 612 virtual jlong millis_since_last_gc() = 0; 613 614 // Perform any cleanup actions necessary before allowing a verification. 615 virtual void prepare_for_verify() = 0; 616 617 // Generate any dumps preceding or following a full gc 618 void pre_full_gc_dump(); 619 void post_full_gc_dump(); 620 621 // Print heap information on the given outputStream. 622 virtual void print_on(outputStream* st) const = 0; 623 // The default behavior is to call print_on() on tty. 624 virtual void print() const { 625 print_on(tty); 626 } 627 // Print more detailed heap information on the given 628 // outputStream. The default behaviour is to call print_on(). It is 629 // up to each subclass to override it and add any additional output 630 // it needs. 631 virtual void print_extended_on(outputStream* st) const { 632 print_on(st); 633 } 634 635 // Print all GC threads (other than the VM thread) 636 // used by this heap. 637 virtual void print_gc_threads_on(outputStream* st) const = 0; 638 // The default behavior is to call print_gc_threads_on() on tty. 639 void print_gc_threads() { 640 print_gc_threads_on(tty); 641 } 642 // Iterator for all GC threads (other than VM thread) 643 virtual void gc_threads_do(ThreadClosure* tc) const = 0; 644 645 // Print any relevant tracing info that flags imply. 646 // Default implementation does nothing. 647 virtual void print_tracing_info() const = 0; 648 649 // If PrintHeapAtGC is set call the appropriate routi 650 void print_heap_before_gc() { 651 if (PrintHeapAtGC) { 652 Universe::print_heap_before_gc(); 653 } 654 if (_gc_heap_log != NULL) { 655 _gc_heap_log->log_heap_before(); 656 } 657 } 658 void print_heap_after_gc() { 659 if (PrintHeapAtGC) { 660 Universe::print_heap_after_gc(); 661 } 662 if (_gc_heap_log != NULL) { 663 _gc_heap_log->log_heap_after(); 664 } 665 } 666 667 // Allocate GCHeapLog during VM startup 668 static void initialize_heap_log(); 669 670 // Heap verification 671 virtual void verify(bool allow_dirty, bool silent, VerifyOption option) = 0; 672 673 // Non product verification and debugging. 674 #ifndef PRODUCT 675 // Support for PromotionFailureALot. Return true if it's time to cause a 676 // promotion failure. The no-argument version uses 677 // this->_promotion_failure_alot_count as the counter. 678 inline bool promotion_should_fail(volatile size_t* count); 679 inline bool promotion_should_fail(); 680 681 // Reset the PromotionFailureALot counters. Should be called at the end of a 682 // GC in which promotion failure ocurred. 683 inline void reset_promotion_should_fail(volatile size_t* count); 684 inline void reset_promotion_should_fail(); 685 #endif // #ifndef PRODUCT 686 687 #ifdef ASSERT 688 static int fired_fake_oom() { 689 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt); 690 } 691 #endif 692 693 public: 694 // This is a convenience method that is used in cases where 695 // the actual number of GC worker threads is not pertinent but 696 // only whether there more than 0. Use of this method helps 697 // reduce the occurrence of ParallelGCThreads to uses where the 698 // actual number may be germane. 699 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; } 700 701 /////////////// Unit tests /////////////// 702 703 NOT_PRODUCT(static void test_is_in();) 704 }; 705 706 // Class to set and reset the GC cause for a CollectedHeap. 707 708 class GCCauseSetter : StackObj { 709 CollectedHeap* _heap; 710 GCCause::Cause _previous_cause; 711 public: 712 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) { 713 assert(SafepointSynchronize::is_at_safepoint(), 714 "This method manipulates heap state without locking"); 715 _heap = heap; 716 _previous_cause = _heap->gc_cause(); 717 _heap->set_gc_cause(cause); 718 } 719 720 ~GCCauseSetter() { 721 assert(SafepointSynchronize::is_at_safepoint(), 722 "This method manipulates heap state without locking"); 723 _heap->set_gc_cause(_previous_cause); 724 } 725 }; 726 727 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP