/*

 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

#ifndef SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP

#define SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP

#include "gc_interface/gcCause.hpp"

#include "memory/allocation.hpp"

#include "memory/barrierSet.hpp"

#include "runtime/handles.hpp"

#include "runtime/perfData.hpp"

#include "runtime/safepoint.hpp"

#include "utilities/events.hpp"

// A "CollectedHeap" is an implementation of a java heap for HotSpot.  This

// is an abstract class: there may be many different kinds of heaps.  This

// class defines the functions that a heap must implement, and contains

// infrastructure common to all heaps.

class BarrierSet;

class ThreadClosure;

class AdaptiveSizePolicy;

class Thread;

class CollectorPolicy;

class GCMessage : public FormatBuffer<1024> {

 public:

  bool is_before;

 public:

  GCMessage() {}

};

class GCHeapLog : public EventLogBase<GCMessage> {

 private:

  void log_heap(bool before);

 public:

  GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}

  void log_heap_before() {

    log_heap(true);

  }

  void log_heap_after() {

    log_heap(false);

  }

};

//

// CollectedHeap

//   SharedHeap

//     GenCollectedHeap

//     G1CollectedHeap

//   ParallelScavengeHeap

//

class CollectedHeap : public CHeapObj {

  friend class VMStructs;

  friend class IsGCActiveMark; // Block structured external access to _is_gc_active

  friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe

#ifdef ASSERT

  static int       _fire_out_of_memory_count;

#endif

  // Used for filler objects (static, but initialized in ctor).

  static size_t _filler_array_max_size;

  GCHeapLog* _gc_heap_log;

  // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used

  bool _defer_initial_card_mark;

 protected:

  MemRegion _reserved;

  BarrierSet* _barrier_set;

  bool _is_gc_active;

  uint _n_par_threads;

  unsigned int _total_collections;          // ... started

  unsigned int _total_full_collections;     // ... started

  NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)

  NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)

  // Reason for current garbage collection.  Should be set to

  // a value reflecting no collection between collections.

  GCCause::Cause _gc_cause;

  GCCause::Cause _gc_lastcause;

  PerfStringVariable* _perf_gc_cause;

  PerfStringVariable* _perf_gc_lastcause;

  // Constructor

  CollectedHeap();

  // Do common initializations that must follow instance construction,

  // for example, those needing virtual calls.

  // This code could perhaps be moved into initialize() but would

  // be slightly more awkward because we want the latter to be a

  // pure virtual.

  void pre_initialize();

  // Create a new tlab. All TLAB allocations must go through this.

  virtual HeapWord* allocate_new_tlab(size_t size);

  // Accumulate statistics on all tlabs.

  virtual void accumulate_statistics_all_tlabs();

  // Reinitialize tlabs before resuming mutators.

  virtual void resize_all_tlabs();

  // Allocate from the current thread's TLAB, with broken-out slow path.

  inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);

  static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);

  // Allocate an uninitialized block of the given size, or returns NULL if

  // this is impossible.

  inline static HeapWord* common_mem_allocate_noinit(size_t size, TRAPS);

  // Like allocate_init, but the block returned by a successful allocation

  // is guaranteed initialized to zeros.

  inline static HeapWord* common_mem_allocate_init(size_t size, TRAPS);

  // Same as common_mem version, except memory is allocated in the permanent area

  // If there is no permanent area, revert to common_mem_allocate_noinit

  inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);

  // Same as common_mem version, except memory is allocated in the permanent area

  // If there is no permanent area, revert to common_mem_allocate_init

  inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);

  // Helper functions for (VM) allocation.

  inline static void post_allocation_setup_common(KlassHandle klass, HeapWord* obj);

  inline static void post_allocation_setup_no_klass_install(KlassHandle klass,

                                                            HeapWord* objPtr);

  inline static void post_allocation_setup_obj(KlassHandle klass, HeapWord* obj);

  inline static void post_allocation_setup_array(KlassHandle klass,

                                                 HeapWord* obj, int length);

  // Clears an allocated object.

  inline static void init_obj(HeapWord* obj, size_t size);

  // Filler object utilities.

  static inline size_t filler_array_hdr_size();

  static inline size_t filler_array_min_size();

  DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)

  DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)

  // Fill with a single array; caller must ensure filler_array_min_size() <=

  // words <= filler_array_max_size().

  static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);

  // Fill with a single object (either an int array or a java.lang.Object).

  static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);

  // Verification functions

  virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)

    PRODUCT_RETURN;

  virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)

    PRODUCT_RETURN;

  debug_only(static void check_for_valid_allocation_state();)

 public:

  enum Name {

    Abstract,

    SharedHeap,

    GenCollectedHeap,

    ParallelScavengeHeap,

    G1CollectedHeap

  };

  static inline size_t filler_array_max_size() {

    return _filler_array_max_size;

  }

  virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }

  /**

   * Returns JNI error code JNI_ENOMEM if memory could not be allocated,

   * and JNI_OK on success.

   */

  virtual jint initialize() = 0;

  // In many heaps, there will be a need to perform some initialization activities

  // after the Universe is fully formed, but before general heap allocation is allowed.

  // This is the correct place to place such initialization methods.

  virtual void post_initialize() = 0;

  MemRegion reserved_region() const { return _reserved; }

  address base() const { return (address)reserved_region().start(); }

  // Future cleanup here. The following functions should specify bytes or

  // heapwords as part of their signature.

  virtual size_t capacity() const = 0;

  virtual size_t used() const = 0;

  // Return "true" if the part of the heap that allocates Java

  // objects has reached the maximal committed limit that it can

  // reach, without a garbage collection.

  virtual bool is_maximal_no_gc() const = 0;

  virtual size_t permanent_capacity() const = 0;

  virtual size_t permanent_used() const = 0;

  // Support for java.lang.Runtime.maxMemory():  return the maximum amount of

  // memory that the vm could make available for storing 'normal' java objects.

  // This is based on the reserved address space, but should not include space

  // that the vm uses internally for bookkeeping or temporary storage (e.g.,

  // perm gen space or, in the case of the young gen, one of the survivor

  // spaces).

  virtual size_t max_capacity() const = 0;

  // Returns "TRUE" if "p" points into the reserved area of the heap.

  bool is_in_reserved(const void* p) const {

    return _reserved.contains(p);

  }

  bool is_in_reserved_or_null(const void* p) const {

    return p == NULL || is_in_reserved(p);

  }

  // Returns "TRUE" iff "p" points into the committed areas of the heap.

  // Since this method can be expensive in general, we restrict its

  // use to assertion checking only.

  virtual bool is_in(const void* p) const = 0;

  bool is_in_or_null(const void* p) const {

    return p == NULL || is_in(p);

  }

  // Let's define some terms: a "closed" subset of a heap is one that

  //

  // 1) contains all currently-allocated objects, and

  //

  // 2) is closed under reference: no object in the closed subset

  //    references one outside the closed subset.

  //

  // Membership in a heap's closed subset is useful for assertions.

  // Clearly, the entire heap is a closed subset, so the default

  // implementation is to use "is_in_reserved".  But this may not be too

  // liberal to perform useful checking.  Also, the "is_in" predicate

  // defines a closed subset, but may be too expensive, since "is_in"

  // verifies that its argument points to an object head.  The

  // "closed_subset" method allows a heap to define an intermediate

  // predicate, allowing more precise checking than "is_in_reserved" at

  // lower cost than "is_in."

  // One important case is a heap composed of disjoint contiguous spaces,

  // such as the Garbage-First collector.  Such heaps have a convenient

  // closed subset consisting of the allocated portions of those

  // contiguous spaces.

  // Return "TRUE" iff the given pointer points into the heap's defined

  // closed subset (which defaults to the entire heap).

  virtual bool is_in_closed_subset(const void* p) const {

    return is_in_reserved(p);

  }

  bool is_in_closed_subset_or_null(const void* p) const {

    return p == NULL || is_in_closed_subset(p);

  }

  // XXX is_permanent() and is_in_permanent() should be better named

  // to distinguish one from the other.

  // Returns "TRUE" if "p" is allocated as "permanent" data.

  // If the heap does not use "permanent" data, returns the same

  // value is_in_reserved() would return.

  // NOTE: this actually returns true if "p" is in reserved space

  // for the space not that it is actually allocated (i.e. in committed

  // space). If you need the more conservative answer use is_permanent().

  virtual bool is_in_permanent(const void *p) const = 0;

#ifdef ASSERT

  // Returns true if "p" is in the part of the

  // heap being collected.

  virtual bool is_in_partial_collection(const void *p) = 0;

#endif

  bool is_in_permanent_or_null(const void *p) const {

    return p == NULL || is_in_permanent(p);

  }

  // Returns "TRUE" if "p" is in the committed area of  "permanent" data.

  // If the heap does not use "permanent" data, returns the same

  // value is_in() would return.

  virtual bool is_permanent(const void *p) const = 0;

  bool is_permanent_or_null(const void *p) const {

    return p == NULL || is_permanent(p);

  }

  // An object is scavengable if its location may move during a scavenge.

  // (A scavenge is a GC which is not a full GC.)

  virtual bool is_scavengable(const void *p) = 0;

  // Returns "TRUE" if "p" is a method oop in the

  // current heap, with high probability. This predicate

  // is not stable, in general.

  bool is_valid_method(oop p) const;

  void set_gc_cause(GCCause::Cause v) {

     if (UsePerfData) {

       _gc_lastcause = _gc_cause;

       _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));

       _perf_gc_cause->set_value(GCCause::to_string(v));

     }

    _gc_cause = v;

  }

  GCCause::Cause gc_cause() { return _gc_cause; }

  // Number of threads currently working on GC tasks.

  uint n_par_threads() { return _n_par_threads; }

  // May be overridden to set additional parallelism.

  virtual void set_par_threads(uint t) { _n_par_threads = t; };

  // Preload classes into the shared portion of the heap, and then dump

  // that data to a file so that it can be loaded directly by another

  // VM (then terminate).

  virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }

  // Allocate and initialize instances of Class

  static oop Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS);

  // General obj/array allocation facilities.

  inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);

  inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);

  inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS);

  // Special obj/array allocation facilities.

  // Some heaps may want to manage "permanent" data uniquely. These default

  // to the general routines if the heap does not support such handling.

  inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);

  // permanent_obj_allocate_no_klass_install() does not do the installation of

  // the klass pointer in the newly created object (as permanent_obj_allocate()

  // above does).  This allows for a delay in the installation of the klass

  // pointer that is needed during the create of klassKlass's.  The

  // method post_allocation_install_obj_klass() is used to install the

  // klass pointer.

  inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,

                                                            int size,

                                                            TRAPS);

  inline static void post_allocation_install_obj_klass(KlassHandle klass, oop obj);

  inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);

  // Raw memory allocation facilities

  // The obj and array allocate methods are covers for these methods.

  // The permanent allocation method should default to mem_allocate if

  // permanent memory isn't supported. mem_allocate() should never be

  // called to allocate TLABs, only individual objects.

  virtual HeapWord* mem_allocate(size_t size,

                                 bool* gc_overhead_limit_was_exceeded) = 0;

  virtual HeapWord* permanent_mem_allocate(size_t size) = 0;

  // Utilities for turning raw memory into filler objects.

  //

  // min_fill_size() is the smallest region that can be filled.

  // fill_with_objects() can fill arbitrary-sized regions of the heap using

  // multiple objects.  fill_with_object() is for regions known to be smaller

  // than the largest array of integers; it uses a single object to fill the

  // region and has slightly less overhead.

  static size_t min_fill_size() {

    return size_t(align_object_size(oopDesc::header_size()));

  }

  static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);

  static void fill_with_object(HeapWord* start, size_t words, bool zap = true);

  static void fill_with_object(MemRegion region, bool zap = true) {

    fill_with_object(region.start(), region.word_size(), zap);

  }

  static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {

    fill_with_object(start, pointer_delta(end, start), zap);

  }

  // Some heaps may offer a contiguous region for shared non-blocking

  // allocation, via inlined code (by exporting the address of the top and

  // end fields defining the extent of the contiguous allocation region.)

  // This function returns "true" iff the heap supports this kind of

  // allocation.  (Default is "no".)

  virtual bool supports_inline_contig_alloc() const {

    return false;

  }

  // These functions return the addresses of the fields that define the

  // boundaries of the contiguous allocation area.  (These fields should be

  // physically near to one another.)

  virtual HeapWord** top_addr() const {

    guarantee(false, "inline contiguous allocation not supported");

    return NULL;

  }

  virtual HeapWord** end_addr() const {

    guarantee(false, "inline contiguous allocation not supported");

    return NULL;

  }

  // Some heaps may be in an unparseable state at certain times between

  // collections. This may be necessary for efficient implementation of

  // certain allocation-related activities. Calling this function before

  // attempting to parse a heap ensures that the heap is in a parsable

  // state (provided other concurrent activity does not introduce

  // unparsability). It is normally expected, therefore, that this

  // method is invoked with the world stopped.

  // NOTE: if you override this method, make sure you call

  // super::ensure_parsability so that the non-generational

  // part of the work gets done. See implementation of

  // CollectedHeap::ensure_parsability and, for instance,

  // that of GenCollectedHeap::ensure_parsability().

  // The argument "retire_tlabs" controls whether existing TLABs

  // are merely filled or also retired, thus preventing further

  // allocation from them and necessitating allocation of new TLABs.

  virtual void ensure_parsability(bool retire_tlabs);

  // Return an estimate of the maximum allocation that could be performed

  // without triggering any collection or expansion activity.  In a

  // generational collector, for example, this is probably the largest

  // allocation that could be supported (without expansion) in the youngest

  // generation.  It is "unsafe" because no locks are taken; the result

  // should be treated as an approximation, not a guarantee, for use in

  // heuristic resizing decisions.

  virtual size_t unsafe_max_alloc() = 0;

  // Section on thread-local allocation buffers (TLABs)

  // If the heap supports thread-local allocation buffers, it should override

  // the following methods:

  // Returns "true" iff the heap supports thread-local allocation buffers.

  // The default is "no".

  virtual bool supports_tlab_allocation() const {

    return false;

  }

  // The amount of space available for thread-local allocation buffers.

  virtual size_t tlab_capacity(Thread *thr) const {

    guarantee(false, "thread-local allocation buffers not supported");

    return 0;

  }

  // An estimate of the maximum allocation that could be performed

  // for thread-local allocation buffers without triggering any

  // collection or expansion activity.

  virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {

    guarantee(false, "thread-local allocation buffers not supported");

    return 0;

  }

  // Can a compiler initialize a new object without store barriers?

  // This permission only extends from the creation of a new object

  // via a TLAB up to the first subsequent safepoint. If such permission

  // is granted for this heap type, the compiler promises to call

  // defer_store_barrier() below on any slow path allocation of

  // a new object for which such initializing store barriers will

  // have been elided.

  virtual bool can_elide_tlab_store_barriers() const = 0;

  // If a compiler is eliding store barriers for TLAB-allocated objects,

  // there is probably a corresponding slow path which can produce

  // an object allocated anywhere.  The compiler's runtime support

  // promises to call this function on such a slow-path-allocated

  // object before performing initializations that have elided

  // store barriers. Returns new_obj, or maybe a safer copy thereof.

  virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);

  // Answers whether an initializing store to a new object currently

  // allocated at the given address doesn't need a store

  // barrier. Returns "true" if it doesn't need an initializing

  // store barrier; answers "false" if it does.

  virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;

  // If a compiler is eliding store barriers for TLAB-allocated objects,

  // we will be informed of a slow-path allocation by a call

  // to new_store_pre_barrier() above. Such a call precedes the

  // initialization of the object itself, and no post-store-barriers will

  // be issued. Some heap types require that the barrier strictly follows

  // the initializing stores. (This is currently implemented by deferring the

  // barrier until the next slow-path allocation or gc-related safepoint.)

  // This interface answers whether a particular heap type needs the card

  // mark to be thus strictly sequenced after the stores.

  virtual bool card_mark_must_follow_store() const = 0;

  // If the CollectedHeap was asked to defer a store barrier above,

  // this informs it to flush such a deferred store barrier to the

  // remembered set.

  virtual void flush_deferred_store_barrier(JavaThread* thread);

  // Can a compiler elide a store barrier when it writes

  // a permanent oop into the heap?  Applies when the compiler

  // is storing x to the heap, where x->is_perm() is true.

  virtual bool can_elide_permanent_oop_store_barriers() const = 0;