1 /*
   2  * Copyright (c) 2001, 2019, 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_GC_SHARED_COLLECTEDHEAP_HPP
  26 #define SHARE_GC_SHARED_COLLECTEDHEAP_HPP
  27 
  28 #include "gc/shared/gcCause.hpp"
  29 #include "gc/shared/gcWhen.hpp"
  30 #include "gc/shared/verifyOption.hpp"
  31 #include "memory/allocation.hpp"
  32 #include "runtime/handles.hpp"
  33 #include "runtime/perfData.hpp"
  34 #include "runtime/safepoint.hpp"
  35 #include "services/memoryUsage.hpp"
  36 #include "utilities/debug.hpp"
  37 #include "utilities/events.hpp"
  38 #include "utilities/formatBuffer.hpp"
  39 #include "utilities/growableArray.hpp"
  40 
  41 // A "CollectedHeap" is an implementation of a java heap for HotSpot.  This
  42 // is an abstract class: there may be many different kinds of heaps.  This
  43 // class defines the functions that a heap must implement, and contains
  44 // infrastructure common to all heaps.
  45 
  46 class AdaptiveSizePolicy;
  47 class BarrierSet;
  48 class GCHeapSummary;
  49 class GCTimer;
  50 class GCTracer;
  51 class GCMemoryManager;
  52 class MemoryPool;
  53 class MetaspaceSummary;
  54 class SoftRefPolicy;
  55 class Thread;
  56 class ThreadClosure;
  57 class VirtualSpaceSummary;
  58 class WorkGang;
  59 class nmethod;
  60 
  61 class GCMessage : public FormatBuffer<1024> {
  62  public:
  63   bool is_before;
  64 
  65  public:
  66   GCMessage() {}
  67 };
  68 
  69 class CollectedHeap;
  70 
  71 class GCHeapLog : public EventLogBase<GCMessage> {
  72  private:
  73   void log_heap(CollectedHeap* heap, bool before);
  74 
  75  public:
  76   GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
  77 
  78   void log_heap_before(CollectedHeap* heap) {
  79     log_heap(heap, true);
  80   }
  81   void log_heap_after(CollectedHeap* heap) {
  82     log_heap(heap, false);
  83   }
  84 };
  85 
  86 //
  87 // CollectedHeap
  88 //   GenCollectedHeap
  89 //     SerialHeap
  90 //     CMSHeap
  91 //   G1CollectedHeap
  92 //   ParallelScavengeHeap
  93 //   ShenandoahHeap
  94 //   ZCollectedHeap
  95 //
  96 class CollectedHeap : public CHeapObj<mtInternal> {
  97   friend class VMStructs;
  98   friend class JVMCIVMStructs;
  99   friend class IsGCActiveMark; // Block structured external access to _is_gc_active
 100   friend class MemAllocator;
 101 
 102  private:
 103   GCHeapLog* _gc_heap_log;
 104 
 105   MemRegion _reserved;
 106 
 107  protected:
 108   bool _is_gc_active;
 109 
 110   // Used for filler objects (static, but initialized in ctor).
 111   static size_t _filler_array_max_size;
 112 
 113   unsigned int _total_collections;          // ... started
 114   unsigned int _total_full_collections;     // ... started
 115   NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
 116   NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
 117 
 118   // Reason for current garbage collection.  Should be set to
 119   // a value reflecting no collection between collections.
 120   GCCause::Cause _gc_cause;
 121   GCCause::Cause _gc_lastcause;
 122   PerfStringVariable* _perf_gc_cause;
 123   PerfStringVariable* _perf_gc_lastcause;
 124 
 125   // Constructor
 126   CollectedHeap();
 127 
 128   // Create a new tlab. All TLAB allocations must go through this.
 129   // To allow more flexible TLAB allocations min_size specifies
 130   // the minimum size needed, while requested_size is the requested
 131   // size based on ergonomics. The actually allocated size will be
 132   // returned in actual_size.
 133   virtual HeapWord* allocate_new_tlab(size_t min_size,
 134                                       size_t requested_size,
 135                                       size_t* actual_size);
 136 
 137   // Reinitialize tlabs before resuming mutators.
 138   virtual void resize_all_tlabs();
 139 
 140   // Raw memory allocation facilities
 141   // The obj and array allocate methods are covers for these methods.
 142   // mem_allocate() should never be
 143   // called to allocate TLABs, only individual objects.
 144   virtual HeapWord* mem_allocate(size_t size,
 145                                  bool* gc_overhead_limit_was_exceeded) = 0;
 146 
 147   // Filler object utilities.
 148   static inline size_t filler_array_hdr_size();
 149   static inline size_t filler_array_min_size();
 150 
 151   DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
 152   DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
 153 
 154   // Fill with a single array; caller must ensure filler_array_min_size() <=
 155   // words <= filler_array_max_size().
 156   static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
 157 
 158   // Fill with a single object (either an int array or a java.lang.Object).
 159   static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
 160 
 161   virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 162 
 163   // Verification functions
 164   virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
 165     PRODUCT_RETURN;
 166   debug_only(static void check_for_valid_allocation_state();)
 167 
 168  public:
 169   enum Name {
 170     None,
 171     Serial,
 172     Parallel,
 173     CMS,
 174     G1,
 175     Epsilon,
 176     Z,
 177     Shenandoah
 178   };
 179 
 180   static inline size_t filler_array_max_size() {
 181     return _filler_array_max_size;
 182   }
 183 
 184   virtual Name kind() const = 0;
 185 
 186   virtual const char* name() const = 0;
 187 
 188   /**
 189    * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
 190    * and JNI_OK on success.
 191    */
 192   virtual jint initialize() = 0;
 193 
 194   // In many heaps, there will be a need to perform some initialization activities
 195   // after the Universe is fully formed, but before general heap allocation is allowed.
 196   // This is the correct place to place such initialization methods.
 197   virtual void post_initialize();
 198 
 199   // Stop any onging concurrent work and prepare for exit.
 200   virtual void stop() {}
 201 
 202   // Stop and resume concurrent GC threads interfering with safepoint operations
 203   virtual void safepoint_synchronize_begin() {}
 204   virtual void safepoint_synchronize_end() {}
 205 
 206   void initialize_reserved_region(HeapWord *start, HeapWord *end);
 207   MemRegion reserved_region() const { return _reserved; }
 208   address base() const { return (address)reserved_region().start(); }
 209 
 210   virtual size_t capacity() const = 0;
 211   virtual size_t used() const = 0;
 212 
 213   // Returns unused capacity.
 214   virtual size_t unused() const;
 215 
 216   // Return "true" if the part of the heap that allocates Java
 217   // objects has reached the maximal committed limit that it can
 218   // reach, without a garbage collection.
 219   virtual bool is_maximal_no_gc() const = 0;
 220 
 221   // Support for java.lang.Runtime.maxMemory():  return the maximum amount of
 222   // memory that the vm could make available for storing 'normal' java objects.
 223   // This is based on the reserved address space, but should not include space
 224   // that the vm uses internally for bookkeeping or temporary storage
 225   // (e.g., in the case of the young gen, one of the survivor
 226   // spaces).
 227   virtual size_t max_capacity() const = 0;
 228 
 229   // Returns "TRUE" if "p" points into the reserved area of the heap.
 230   bool is_in_reserved(const void* p) const {
 231     return _reserved.contains(p);
 232   }
 233 
 234   bool is_in_reserved_or_null(const void* p) const {
 235     return p == NULL || is_in_reserved(p);
 236   }
 237 
 238   // Returns "TRUE" iff "p" points into the committed areas of the heap.
 239   // This method can be expensive so avoid using it in performance critical
 240   // code.
 241   virtual bool is_in(const void* p) const = 0;
 242 
 243   DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
 244 
 245   virtual uint32_t hash_oop(oop obj) const;
 246 
 247   void set_gc_cause(GCCause::Cause v) {
 248      if (UsePerfData) {
 249        _gc_lastcause = _gc_cause;
 250        _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
 251        _perf_gc_cause->set_value(GCCause::to_string(v));
 252      }
 253     _gc_cause = v;
 254   }
 255   GCCause::Cause gc_cause() { return _gc_cause; }
 256 
 257   virtual oop obj_allocate(Klass* klass, int size, TRAPS);
 258   virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
 259   virtual oop class_allocate(Klass* klass, int size, TRAPS);
 260 
 261   // Utilities for turning raw memory into filler objects.
 262   //
 263   // min_fill_size() is the smallest region that can be filled.
 264   // fill_with_objects() can fill arbitrary-sized regions of the heap using
 265   // multiple objects.  fill_with_object() is for regions known to be smaller
 266   // than the largest array of integers; it uses a single object to fill the
 267   // region and has slightly less overhead.
 268   static size_t min_fill_size() {
 269     return size_t(align_object_size(oopDesc::header_size()));
 270   }
 271 
 272   static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
 273 
 274   static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
 275   static void fill_with_object(MemRegion region, bool zap = true) {
 276     fill_with_object(region.start(), region.word_size(), zap);
 277   }
 278   static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
 279     fill_with_object(start, pointer_delta(end, start), zap);
 280   }
 281 
 282   virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
 283   virtual size_t min_dummy_object_size() const;
 284   size_t tlab_alloc_reserve() const;
 285 
 286   // Return the address "addr" aligned by "alignment_in_bytes" if such
 287   // an address is below "end".  Return NULL otherwise.
 288   inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
 289                                                    HeapWord* end,
 290                                                    unsigned short alignment_in_bytes);
 291 
 292   // Some heaps may offer a contiguous region for shared non-blocking
 293   // allocation, via inlined code (by exporting the address of the top and
 294   // end fields defining the extent of the contiguous allocation region.)
 295 
 296   // This function returns "true" iff the heap supports this kind of
 297   // allocation.  (Default is "no".)
 298   virtual bool supports_inline_contig_alloc() const {
 299     return false;
 300   }
 301   // These functions return the addresses of the fields that define the
 302   // boundaries of the contiguous allocation area.  (These fields should be
 303   // physically near to one another.)
 304   virtual HeapWord* volatile* top_addr() const {
 305     guarantee(false, "inline contiguous allocation not supported");
 306     return NULL;
 307   }
 308   virtual HeapWord** end_addr() const {
 309     guarantee(false, "inline contiguous allocation not supported");
 310     return NULL;
 311   }
 312 
 313   // Some heaps may be in an unparseable state at certain times between
 314   // collections. This may be necessary for efficient implementation of
 315   // certain allocation-related activities. Calling this function before
 316   // attempting to parse a heap ensures that the heap is in a parsable
 317   // state (provided other concurrent activity does not introduce
 318   // unparsability). It is normally expected, therefore, that this
 319   // method is invoked with the world stopped.
 320   // NOTE: if you override this method, make sure you call
 321   // super::ensure_parsability so that the non-generational
 322   // part of the work gets done. See implementation of
 323   // CollectedHeap::ensure_parsability and, for instance,
 324   // that of GenCollectedHeap::ensure_parsability().
 325   // The argument "retire_tlabs" controls whether existing TLABs
 326   // are merely filled or also retired, thus preventing further
 327   // allocation from them and necessitating allocation of new TLABs.
 328   virtual void ensure_parsability(bool retire_tlabs);
 329 
 330   // Section on thread-local allocation buffers (TLABs)
 331   // If the heap supports thread-local allocation buffers, it should override
 332   // the following methods:
 333   // Returns "true" iff the heap supports thread-local allocation buffers.
 334   // The default is "no".
 335   virtual bool supports_tlab_allocation() const = 0;
 336 
 337   // The amount of space available for thread-local allocation buffers.
 338   virtual size_t tlab_capacity(Thread *thr) const = 0;
 339 
 340   // The amount of used space for thread-local allocation buffers for the given thread.
 341   virtual size_t tlab_used(Thread *thr) const = 0;
 342 
 343   virtual size_t max_tlab_size() const;
 344 
 345   // An estimate of the maximum allocation that could be performed
 346   // for thread-local allocation buffers without triggering any
 347   // collection or expansion activity.
 348   virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
 349     guarantee(false, "thread-local allocation buffers not supported");
 350     return 0;
 351   }
 352 
 353   // Perform a collection of the heap; intended for use in implementing
 354   // "System.gc".  This probably implies as full a collection as the
 355   // "CollectedHeap" supports.
 356   virtual void collect(GCCause::Cause cause) = 0;
 357 
 358   // Perform a full collection
 359   virtual void do_full_collection(bool clear_all_soft_refs) = 0;
 360 
 361   // This interface assumes that it's being called by the
 362   // vm thread. It collects the heap assuming that the
 363   // heap lock is already held and that we are executing in
 364   // the context of the vm thread.
 365   virtual void collect_as_vm_thread(GCCause::Cause cause);
 366 
 367   virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 368                                                        size_t size,
 369                                                        Metaspace::MetadataType mdtype);
 370 
 371   // Returns "true" iff there is a stop-world GC in progress.  (I assume
 372   // that it should answer "false" for the concurrent part of a concurrent
 373   // collector -- dld).
 374   bool is_gc_active() const { return _is_gc_active; }
 375 
 376   // Total number of GC collections (started)
 377   unsigned int total_collections() const { return _total_collections; }
 378   unsigned int total_full_collections() const { return _total_full_collections;}
 379 
 380   // Increment total number of GC collections (started)
 381   // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
 382   void increment_total_collections(bool full = false) {
 383     _total_collections++;
 384     if (full) {
 385       increment_total_full_collections();
 386     }
 387   }
 388 
 389   void increment_total_full_collections() { _total_full_collections++; }
 390 
 391   // Return the SoftRefPolicy for the heap;
 392   virtual SoftRefPolicy* soft_ref_policy() = 0;
 393 
 394   virtual MemoryUsage memory_usage();
 395   virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
 396   virtual GrowableArray<MemoryPool*> memory_pools() = 0;
 397 
 398   // Iterate over all objects, calling "cl.do_object" on each.
 399   virtual void object_iterate(ObjectClosure* cl) = 0;
 400 
 401   // Similar to object_iterate() except iterates only
 402   // over live objects.
 403   virtual void safe_object_iterate(ObjectClosure* cl) = 0;
 404 
 405   // NOTE! There is no requirement that a collector implement these
 406   // functions.
 407   //
 408   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
 409   // each address in the (reserved) heap is a member of exactly
 410   // one block.  The defining characteristic of a block is that it is
 411   // possible to find its size, and thus to progress forward to the next
 412   // block.  (Blocks may be of different sizes.)  Thus, blocks may
 413   // represent Java objects, or they might be free blocks in a
 414   // free-list-based heap (or subheap), as long as the two kinds are
 415   // distinguishable and the size of each is determinable.
 416 
 417   // Returns the address of the start of the "block" that contains the
 418   // address "addr".  We say "blocks" instead of "object" since some heaps
 419   // may not pack objects densely; a chunk may either be an object or a
 420   // non-object.
 421   virtual HeapWord* block_start(const void* addr) const = 0;
 422 
 423   // Requires "addr" to be the start of a block, and returns "TRUE" iff
 424   // the block is an object.
 425   virtual bool block_is_obj(const HeapWord* addr) const = 0;
 426 
 427   // Returns the longest time (in ms) that has elapsed since the last
 428   // time that any part of the heap was examined by a garbage collection.
 429   virtual jlong millis_since_last_gc() = 0;
 430 
 431   // Perform any cleanup actions necessary before allowing a verification.
 432   virtual void prepare_for_verify() = 0;
 433 
 434   // Generate any dumps preceding or following a full gc
 435  private:
 436   void full_gc_dump(GCTimer* timer, bool before);
 437 
 438   virtual void initialize_serviceability() = 0;
 439 
 440  public:
 441   void pre_full_gc_dump(GCTimer* timer);
 442   void post_full_gc_dump(GCTimer* timer);
 443 
 444   virtual VirtualSpaceSummary create_heap_space_summary();
 445   GCHeapSummary create_heap_summary();
 446 
 447   MetaspaceSummary create_metaspace_summary();
 448 
 449   // Print heap information on the given outputStream.
 450   virtual void print_on(outputStream* st) const = 0;
 451   // The default behavior is to call print_on() on tty.
 452   virtual void print() const;
 453 
 454   // Print more detailed heap information on the given
 455   // outputStream. The default behavior is to call print_on(). It is
 456   // up to each subclass to override it and add any additional output
 457   // it needs.
 458   virtual void print_extended_on(outputStream* st) const {
 459     print_on(st);
 460   }
 461 
 462   virtual void print_on_error(outputStream* st) const;
 463 
 464   // Print all GC threads (other than the VM thread)
 465   // used by this heap.
 466   virtual void print_gc_threads_on(outputStream* st) const = 0;
 467   // The default behavior is to call print_gc_threads_on() on tty.
 468   void print_gc_threads() {
 469     print_gc_threads_on(tty);
 470   }
 471   // Iterator for all GC threads (other than VM thread)
 472   virtual void gc_threads_do(ThreadClosure* tc) const = 0;
 473 
 474   // Print any relevant tracing info that flags imply.
 475   // Default implementation does nothing.
 476   virtual void print_tracing_info() const = 0;
 477 
 478   void print_heap_before_gc();
 479   void print_heap_after_gc();
 480 
 481   // Registering and unregistering an nmethod (compiled code) with the heap.
 482   virtual void register_nmethod(nmethod* nm) = 0;
 483   virtual void unregister_nmethod(nmethod* nm) = 0;
 484   // Callback for when nmethod is about to be deleted.
 485   virtual void flush_nmethod(nmethod* nm) = 0;
 486   virtual void verify_nmethod(nmethod* nm) = 0;
 487 
 488   void trace_heap_before_gc(const GCTracer* gc_tracer);
 489   void trace_heap_after_gc(const GCTracer* gc_tracer);
 490 
 491   // Heap verification
 492   virtual void verify(VerifyOption option) = 0;
 493 
 494   // Return true if concurrent phase control (via
 495   // request_concurrent_phase_control) is supported by this collector.
 496   // The default implementation returns false.
 497   virtual bool supports_concurrent_phase_control() const;
 498 
 499   // Request the collector enter the indicated concurrent phase, and
 500   // wait until it does so.  Supports WhiteBox testing.  Only one
 501   // request may be active at a time.  Phases are designated by name;
 502   // the set of names and their meaning is GC-specific.  Once the
 503   // requested phase has been reached, the collector will attempt to
 504   // avoid transitioning to a new phase until a new request is made.
 505   // [Note: A collector might not be able to remain in a given phase.
 506   // For example, a full collection might cancel an in-progress
 507   // concurrent collection.]
 508   //
 509   // Returns true when the phase is reached.  Returns false for an
 510   // unknown phase.  The default implementation returns false.
 511   virtual bool request_concurrent_phase(const char* phase);
 512 
 513   // Provides a thread pool to SafepointSynchronize to use
 514   // for parallel safepoint cleanup.
 515   // GCs that use a GC worker thread pool may want to share
 516   // it for use during safepoint cleanup. This is only possible
 517   // if the GC can pause and resume concurrent work (e.g. G1
 518   // concurrent marking) for an intermittent non-GC safepoint.
 519   // If this method returns NULL, SafepointSynchronize will
 520   // perform cleanup tasks serially in the VMThread.
 521   virtual WorkGang* get_safepoint_workers() { return NULL; }
 522 
 523   // Support for object pinning. This is used by JNI Get*Critical()
 524   // and Release*Critical() family of functions. If supported, the GC
 525   // must guarantee that pinned objects never move.
 526   virtual bool supports_object_pinning() const;
 527   virtual oop pin_object(JavaThread* thread, oop obj);
 528   virtual void unpin_object(JavaThread* thread, oop obj);
 529 
 530   // Deduplicate the string, iff the GC supports string deduplication.
 531   virtual void deduplicate_string(oop str);
 532 
 533   virtual bool is_oop(oop object) const;
 534 
 535   virtual size_t obj_size(oop obj) const;
 536 
 537   // Cells are memory slices allocated by the allocator. Objects are initialized
 538   // in cells. The cell itself may have a header, found at a negative offset of
 539   // oops. Usually, the size of the cell header is 0, but it may be larger.
 540   virtual ptrdiff_t cell_header_size() const { return 0; }
 541 
 542   // Non product verification and debugging.
 543 #ifndef PRODUCT
 544   // Support for PromotionFailureALot.  Return true if it's time to cause a
 545   // promotion failure.  The no-argument version uses
 546   // this->_promotion_failure_alot_count as the counter.
 547   bool promotion_should_fail(volatile size_t* count);
 548   bool promotion_should_fail();
 549 
 550   // Reset the PromotionFailureALot counters.  Should be called at the end of a
 551   // GC in which promotion failure occurred.
 552   void reset_promotion_should_fail(volatile size_t* count);
 553   void reset_promotion_should_fail();
 554 #endif  // #ifndef PRODUCT
 555 };
 556 
 557 // Class to set and reset the GC cause for a CollectedHeap.
 558 
 559 class GCCauseSetter : StackObj {
 560   CollectedHeap* _heap;
 561   GCCause::Cause _previous_cause;
 562  public:
 563   GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
 564     _heap = heap;
 565     _previous_cause = _heap->gc_cause();
 566     _heap->set_gc_cause(cause);
 567   }
 568 
 569   ~GCCauseSetter() {
 570     _heap->set_gc_cause(_previous_cause);
 571   }
 572 };
 573 
 574 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP