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.
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  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 ReservedHeapSpace;
  55 class SoftRefPolicy;
  56 class Thread;
  57 class ThreadClosure;
  58 class VirtualSpaceSummary;
  59 class WorkGang;
  60 class nmethod;
  61 
  62 class GCMessage : public FormatBuffer<1024> {
  63  public:
  64   bool is_before;
  65 
  66  public:
  67   GCMessage() {}
  68 };
  69 
  70 class CollectedHeap;
  71 
  72 class GCHeapLog : public EventLogBase<GCMessage> {
  73  private:
  74   void log_heap(CollectedHeap* heap, bool before);
  75 
  76  public:
  77   GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
  78 
  79   void log_heap_before(CollectedHeap* heap) {
  80     log_heap(heap, true);
  81   }
  82   void log_heap_after(CollectedHeap* heap) {
  83     log_heap(heap, false);
  84   }
  85 };
  86 
  87 //
  88 // CollectedHeap
  89 //   GenCollectedHeap
  90 //     SerialHeap
  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  protected:
 106   // Not used by all GCs
 107   MemRegion _reserved;
 108 
 109   bool _is_gc_active;
 110 
 111   // Used for filler objects (static, but initialized in ctor).
 112   static size_t _filler_array_max_size;
 113 
 114   unsigned int _total_collections;          // ... started
 115   unsigned int _total_full_collections;     // ... started
 116   NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
 117   NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
 118 
 119   // Reason for current garbage collection.  Should be set to
 120   // a value reflecting no collection between collections.
 121   GCCause::Cause _gc_cause;
 122   GCCause::Cause _gc_lastcause;
 123   PerfStringVariable* _perf_gc_cause;
 124   PerfStringVariable* _perf_gc_lastcause;
 125 
 126   // Constructor
 127   CollectedHeap();
 128 
 129   // Create a new tlab. All TLAB allocations must go through this.
 130   // To allow more flexible TLAB allocations min_size specifies
 131   // the minimum size needed, while requested_size is the requested
 132   // size based on ergonomics. The actually allocated size will be
 133   // returned in actual_size.
 134   virtual HeapWord* allocate_new_tlab(size_t min_size,
 135                                       size_t requested_size,
 136                                       size_t* actual_size);
 137 
 138   // Reinitialize tlabs before resuming mutators.
 139   virtual void resize_all_tlabs();
 140 
 141   // Raw memory allocation facilities
 142   // The obj and array allocate methods are covers for these methods.
 143   // mem_allocate() should never be
 144   // called to allocate TLABs, only individual objects.
 145   virtual HeapWord* mem_allocate(size_t size,
 146                                  bool* gc_overhead_limit_was_exceeded) = 0;
 147 
 148   // Filler object utilities.
 149   static inline size_t filler_array_hdr_size();
 150   static inline size_t filler_array_min_size();
 151 
 152   DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
 153   DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
 154 
 155   // Fill with a single array; caller must ensure filler_array_min_size() <=
 156   // words <= filler_array_max_size().
 157   static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
 158 
 159   // Fill with a single object (either an int array or a java.lang.Object).
 160   static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
 161 
 162   virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
 163 
 164   // Verification functions
 165   virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
 166     PRODUCT_RETURN;
 167   debug_only(static void check_for_valid_allocation_state();)
 168 
 169  public:
 170   enum Name {
 171     None,
 172     Serial,
 173     Parallel,
 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(const ReservedHeapSpace& rs);
 207 
 208   virtual size_t capacity() const = 0;
 209   virtual size_t used() const = 0;
 210 
 211   // Returns unused capacity.
 212   virtual size_t unused() const;
 213 
 214   // Return "true" if the part of the heap that allocates Java
 215   // objects has reached the maximal committed limit that it can
 216   // reach, without a garbage collection.
 217   virtual bool is_maximal_no_gc() const = 0;
 218 
 219   // Support for java.lang.Runtime.maxMemory():  return the maximum amount of
 220   // memory that the vm could make available for storing 'normal' java objects.
 221   // This is based on the reserved address space, but should not include space
 222   // that the vm uses internally for bookkeeping or temporary storage
 223   // (e.g., in the case of the young gen, one of the survivor
 224   // spaces).
 225   virtual size_t max_capacity() const = 0;
 226 
 227   // Returns "TRUE" iff "p" points into the committed areas of the heap.
 228   // This method can be expensive so avoid using it in performance critical
 229   // code.
 230   virtual bool is_in(const void* p) const = 0;
 231 
 232   DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
 233 
 234   virtual uint32_t hash_oop(oop obj) const;
 235 
 236   void set_gc_cause(GCCause::Cause v) {
 237      if (UsePerfData) {
 238        _gc_lastcause = _gc_cause;
 239        _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
 240        _perf_gc_cause->set_value(GCCause::to_string(v));
 241      }
 242     _gc_cause = v;
 243   }
 244   GCCause::Cause gc_cause() { return _gc_cause; }
 245 
 246   oop obj_allocate(Klass* klass, int size, TRAPS);
 247   virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
 248   oop class_allocate(Klass* klass, int size, TRAPS);
 249 
 250   // Utilities for turning raw memory into filler objects.
 251   //
 252   // min_fill_size() is the smallest region that can be filled.
 253   // fill_with_objects() can fill arbitrary-sized regions of the heap using
 254   // multiple objects.  fill_with_object() is for regions known to be smaller
 255   // than the largest array of integers; it uses a single object to fill the
 256   // region and has slightly less overhead.
 257   static size_t min_fill_size() {
 258     return size_t(align_object_size(oopDesc::header_size()));
 259   }
 260 
 261   static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
 262 
 263   static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
 264   static void fill_with_object(MemRegion region, bool zap = true) {
 265     fill_with_object(region.start(), region.word_size(), zap);
 266   }
 267   static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
 268     fill_with_object(start, pointer_delta(end, start), zap);
 269   }
 270 
 271   virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
 272   virtual size_t min_dummy_object_size() const;
 273   size_t tlab_alloc_reserve() const;
 274 
 275   // Return the address "addr" aligned by "alignment_in_bytes" if such
 276   // an address is below "end".  Return NULL otherwise.
 277   inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
 278                                                    HeapWord* end,
 279                                                    unsigned short alignment_in_bytes);
 280 
 281   // Some heaps may offer a contiguous region for shared non-blocking
 282   // allocation, via inlined code (by exporting the address of the top and
 283   // end fields defining the extent of the contiguous allocation region.)
 284 
 285   // This function returns "true" iff the heap supports this kind of
 286   // allocation.  (Default is "no".)
 287   virtual bool supports_inline_contig_alloc() const {
 288     return false;
 289   }
 290   // These functions return the addresses of the fields that define the
 291   // boundaries of the contiguous allocation area.  (These fields should be
 292   // physically near to one another.)
 293   virtual HeapWord* volatile* top_addr() const {
 294     guarantee(false, "inline contiguous allocation not supported");
 295     return NULL;
 296   }
 297   virtual HeapWord** end_addr() const {
 298     guarantee(false, "inline contiguous allocation not supported");
 299     return NULL;
 300   }
 301 
 302   // Some heaps may be in an unparseable state at certain times between
 303   // collections. This may be necessary for efficient implementation of
 304   // certain allocation-related activities. Calling this function before
 305   // attempting to parse a heap ensures that the heap is in a parsable
 306   // state (provided other concurrent activity does not introduce
 307   // unparsability). It is normally expected, therefore, that this
 308   // method is invoked with the world stopped.
 309   // NOTE: if you override this method, make sure you call
 310   // super::ensure_parsability so that the non-generational
 311   // part of the work gets done. See implementation of
 312   // CollectedHeap::ensure_parsability and, for instance,
 313   // that of GenCollectedHeap::ensure_parsability().
 314   // The argument "retire_tlabs" controls whether existing TLABs
 315   // are merely filled or also retired, thus preventing further
 316   // allocation from them and necessitating allocation of new TLABs.
 317   virtual void ensure_parsability(bool retire_tlabs);
 318 
 319   // Section on thread-local allocation buffers (TLABs)
 320   // If the heap supports thread-local allocation buffers, it should override
 321   // the following methods:
 322   // Returns "true" iff the heap supports thread-local allocation buffers.
 323   // The default is "no".
 324   virtual bool supports_tlab_allocation() const = 0;
 325 
 326   // The amount of space available for thread-local allocation buffers.
 327   virtual size_t tlab_capacity(Thread *thr) const = 0;
 328 
 329   // The amount of used space for thread-local allocation buffers for the given thread.
 330   virtual size_t tlab_used(Thread *thr) const = 0;
 331 
 332   virtual size_t max_tlab_size() const;
 333 
 334   // An estimate of the maximum allocation that could be performed
 335   // for thread-local allocation buffers without triggering any
 336   // collection or expansion activity.
 337   virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
 338     guarantee(false, "thread-local allocation buffers not supported");
 339     return 0;
 340   }
 341 
 342   // Perform a collection of the heap; intended for use in implementing
 343   // "System.gc".  This probably implies as full a collection as the
 344   // "CollectedHeap" supports.
 345   virtual void collect(GCCause::Cause cause) = 0;
 346 
 347   // Perform a full collection
 348   virtual void do_full_collection(bool clear_all_soft_refs) = 0;
 349 
 350   // This interface assumes that it's being called by the
 351   // vm thread. It collects the heap assuming that the
 352   // heap lock is already held and that we are executing in
 353   // the context of the vm thread.
 354   virtual void collect_as_vm_thread(GCCause::Cause cause);
 355 
 356   virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 357                                                        size_t size,
 358                                                        Metaspace::MetadataType mdtype);
 359 
 360   // Returns "true" iff there is a stop-world GC in progress.  (I assume
 361   // that it should answer "false" for the concurrent part of a concurrent
 362   // collector -- dld).
 363   bool is_gc_active() const { return _is_gc_active; }
 364 
 365   // Total number of GC collections (started)
 366   unsigned int total_collections() const { return _total_collections; }
 367   unsigned int total_full_collections() const { return _total_full_collections;}
 368 
 369   // Increment total number of GC collections (started)
 370   void increment_total_collections(bool full = false) {
 371     _total_collections++;
 372     if (full) {
 373       increment_total_full_collections();
 374     }
 375   }
 376 
 377   void increment_total_full_collections() { _total_full_collections++; }
 378 
 379   // Return the SoftRefPolicy for the heap;
 380   virtual SoftRefPolicy* soft_ref_policy() = 0;
 381 
 382   virtual MemoryUsage memory_usage();
 383   virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
 384   virtual GrowableArray<MemoryPool*> memory_pools() = 0;



 385 
 386   // Iterate over all objects, calling "cl.do_object" on each.
 387   virtual void object_iterate(ObjectClosure* cl) = 0;
 388 
 389   // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
 390   virtual void keep_alive(oop obj) {}
 391 
 392   // Returns the longest time (in ms) that has elapsed since the last
 393   // time that any part of the heap was examined by a garbage collection.
 394   virtual jlong millis_since_last_gc() = 0;
 395 
 396   // Perform any cleanup actions necessary before allowing a verification.
 397   virtual void prepare_for_verify() = 0;
 398 
 399   // Generate any dumps preceding or following a full gc
 400  private:
 401   void full_gc_dump(GCTimer* timer, bool before);
 402 
 403   virtual void initialize_serviceability() = 0;
 404 
 405  public:
 406   void pre_full_gc_dump(GCTimer* timer);
 407   void post_full_gc_dump(GCTimer* timer);
 408 
 409   virtual VirtualSpaceSummary create_heap_space_summary();
 410   GCHeapSummary create_heap_summary();
 411 
 412   MetaspaceSummary create_metaspace_summary();
 413 
 414   // Print heap information on the given outputStream.
 415   virtual void print_on(outputStream* st) const = 0;
 416   // The default behavior is to call print_on() on tty.
 417   virtual void print() const;
 418 
 419   // Print more detailed heap information on the given
 420   // outputStream. The default behavior is to call print_on(). It is
 421   // up to each subclass to override it and add any additional output
 422   // it needs.
 423   virtual void print_extended_on(outputStream* st) const {
 424     print_on(st);
 425   }
 426 
 427   virtual void print_on_error(outputStream* st) const;
 428 
 429   // Used to print information about locations in the hs_err file.
 430   virtual bool print_location(outputStream* st, void* addr) const = 0;
 431 
 432   // Print all GC threads (other than the VM thread)
 433   // used by this heap.
 434   virtual void print_gc_threads_on(outputStream* st) const = 0;
 435   // The default behavior is to call print_gc_threads_on() on tty.
 436   void print_gc_threads() {
 437     print_gc_threads_on(tty);
 438   }
 439   // Iterator for all GC threads (other than VM thread)
 440   virtual void gc_threads_do(ThreadClosure* tc) const = 0;
 441 
 442   // Print any relevant tracing info that flags imply.
 443   // Default implementation does nothing.
 444   virtual void print_tracing_info() const = 0;
 445 
 446   void print_heap_before_gc();
 447   void print_heap_after_gc();
 448 
 449   // Registering and unregistering an nmethod (compiled code) with the heap.
 450   virtual void register_nmethod(nmethod* nm) = 0;
 451   virtual void unregister_nmethod(nmethod* nm) = 0;
 452   // Callback for when nmethod is about to be deleted.
 453   virtual void flush_nmethod(nmethod* nm) = 0;
 454   virtual void verify_nmethod(nmethod* nm) = 0;
 455 
 456   void trace_heap_before_gc(const GCTracer* gc_tracer);
 457   void trace_heap_after_gc(const GCTracer* gc_tracer);
 458 
 459   // Heap verification
 460   virtual void verify(VerifyOption option) = 0;
 461 
 462   // Return true if concurrent phase control (via
 463   // request_concurrent_phase_control) is supported by this collector.
 464   // The default implementation returns false.
 465   virtual bool supports_concurrent_phase_control() const;
 466 
 467   // Request the collector enter the indicated concurrent phase, and
 468   // wait until it does so.  Supports WhiteBox testing.  Only one
 469   // request may be active at a time.  Phases are designated by name;
 470   // the set of names and their meaning is GC-specific.  Once the
 471   // requested phase has been reached, the collector will attempt to
 472   // avoid transitioning to a new phase until a new request is made.
 473   // [Note: A collector might not be able to remain in a given phase.
 474   // For example, a full collection might cancel an in-progress
 475   // concurrent collection.]
 476   //
 477   // Returns true when the phase is reached.  Returns false for an
 478   // unknown phase.  The default implementation returns false.
 479   virtual bool request_concurrent_phase(const char* phase);
 480 
 481   // Provides a thread pool to SafepointSynchronize to use
 482   // for parallel safepoint cleanup.
 483   // GCs that use a GC worker thread pool may want to share
 484   // it for use during safepoint cleanup. This is only possible
 485   // if the GC can pause and resume concurrent work (e.g. G1
 486   // concurrent marking) for an intermittent non-GC safepoint.
 487   // If this method returns NULL, SafepointSynchronize will
 488   // perform cleanup tasks serially in the VMThread.
 489   virtual WorkGang* get_safepoint_workers() { return NULL; }
 490 
 491   // Support for object pinning. This is used by JNI Get*Critical()
 492   // and Release*Critical() family of functions. If supported, the GC
 493   // must guarantee that pinned objects never move.
 494   virtual bool supports_object_pinning() const;
 495   virtual oop pin_object(JavaThread* thread, oop obj);
 496   virtual void unpin_object(JavaThread* thread, oop obj);
 497 
 498   // Deduplicate the string, iff the GC supports string deduplication.
 499   virtual void deduplicate_string(oop str);
 500 
 501   virtual bool is_oop(oop object) const;
 502 
 503   virtual size_t obj_size(oop obj) const;
 504 
 505   // Non product verification and debugging.
 506 #ifndef PRODUCT
 507   // Support for PromotionFailureALot.  Return true if it's time to cause a
 508   // promotion failure.  The no-argument version uses
 509   // this->_promotion_failure_alot_count as the counter.
 510   bool promotion_should_fail(volatile size_t* count);
 511   bool promotion_should_fail();
 512 
 513   // Reset the PromotionFailureALot counters.  Should be called at the end of a
 514   // GC in which promotion failure occurred.
 515   void reset_promotion_should_fail(volatile size_t* count);
 516   void reset_promotion_should_fail();
 517 #endif  // #ifndef PRODUCT
 518 };
 519 
 520 // Class to set and reset the GC cause for a CollectedHeap.
 521 
 522 class GCCauseSetter : StackObj {
 523   CollectedHeap* _heap;
 524   GCCause::Cause _previous_cause;
 525  public:
 526   GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
 527     _heap = heap;
 528     _previous_cause = _heap->gc_cause();
 529     _heap->set_gc_cause(cause);
 530   }
 531 
 532   ~GCCauseSetter() {
 533     _heap->set_gc_cause(_previous_cause);
 534   }
 535 };
 536 
 537 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP
--- EOF ---