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#ifndef SHARE_VM_MEMORY_SPACE_HPP

#define SHARE_VM_MEMORY_SPACE_HPP

#include "memory/allocation.hpp"

#include "memory/blockOffsetTable.hpp"

#include "memory/cardTableModRefBS.hpp"

#include "memory/iterator.hpp"

#include "memory/memRegion.hpp"

#include "memory/watermark.hpp"

#include "oops/markOop.hpp"

#include "runtime/mutexLocker.hpp"

#include "utilities/macros.hpp"

#include "utilities/workgroup.hpp"

// A space is an abstraction for the "storage units" backing

// up the generation abstraction. It includes specific

// implementations for keeping track of free and used space,

// for iterating over objects and free blocks, etc.

// Here's the Space hierarchy:

//

// - Space               -- an abstract base class describing a heap area

//   - CompactibleSpace  -- a space supporting compaction

//     - CompactibleFreeListSpace -- (used for CMS generation)

//     - ContiguousSpace -- a compactible space in which all free space

//                          is contiguous

//       - EdenSpace     -- contiguous space used as nursery

//         - ConcEdenSpace -- contiguous space with a 'soft end safe' allocation

//       - OffsetTableContigSpace -- contiguous space with a block offset array

//                          that allows "fast" block_start calls

//         - TenuredSpace -- (used for TenuredGeneration)

// Forward decls.

class Space;

class BlockOffsetArray;

class BlockOffsetArrayContigSpace;

class Generation;

class CompactibleSpace;

class BlockOffsetTable;

class GenRemSet;

class CardTableRS;

class DirtyCardToOopClosure;

// A Space describes a heap area. Class Space is an abstract

// base class.

//

// Space supports allocation, size computation and GC support is provided.

//

// Invariant: bottom() and end() are on page_size boundaries and

// bottom() <= top() <= end()

// top() is inclusive and end() is exclusive.

class Space: public CHeapObj<mtGC> {

  friend class VMStructs;

 protected:

  HeapWord* _bottom;

  HeapWord* _end;

  // Used in support of save_marks()

  HeapWord* _saved_mark_word;

  MemRegionClosure* _preconsumptionDirtyCardClosure;

  // A sequential tasks done structure. This supports

  // parallel GC, where we have threads dynamically

  // claiming sub-tasks from a larger parallel task.

  SequentialSubTasksDone _par_seq_tasks;

  Space():

    _bottom(NULL), _end(NULL), _preconsumptionDirtyCardClosure(NULL) { }

 public:

  // Accessors

  HeapWord* bottom() const         { return _bottom; }

  HeapWord* end() const            { return _end;    }

  virtual void set_bottom(HeapWord* value) { _bottom = value; }

  virtual void set_end(HeapWord* value)    { _end = value; }

  virtual HeapWord* saved_mark_word() const  { return _saved_mark_word; }

  void set_saved_mark_word(HeapWord* p) { _saved_mark_word = p; }

  // Returns true if this object has been allocated since a

  // generation's "save_marks" call.

  virtual bool obj_allocated_since_save_marks(const oop obj) const {

    return (HeapWord*)obj >= saved_mark_word();

  }

  MemRegionClosure* preconsumptionDirtyCardClosure() const {

    return _preconsumptionDirtyCardClosure;

  }

  void setPreconsumptionDirtyCardClosure(MemRegionClosure* cl) {

    _preconsumptionDirtyCardClosure = cl;

  }

  // Returns a subregion of the space containing only the allocated objects in

  // the space.

  virtual MemRegion used_region() const = 0;

  // Returns a region that is guaranteed to contain (at least) all objects

  // allocated at the time of the last call to "save_marks".  If the space

  // initializes its DirtyCardToOopClosure's specifying the "contig" option

  // (that is, if the space is contiguous), then this region must contain only

  // such objects: the memregion will be from the bottom of the region to the

  // saved mark.  Otherwise, the "obj_allocated_since_save_marks" method of

  // the space must distinguish between objects in the region allocated before

  // and after the call to save marks.

  MemRegion used_region_at_save_marks() const {

    return MemRegion(bottom(), saved_mark_word());

  }

  // Initialization.

  // "initialize" should be called once on a space, before it is used for

  // any purpose.  The "mr" arguments gives the bounds of the space, and

  // the "clear_space" argument should be true unless the memory in "mr" is

  // known to be zeroed.

  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);

  // The "clear" method must be called on a region that may have

  // had allocation performed in it, but is now to be considered empty.

  virtual void clear(bool mangle_space);

  // For detecting GC bugs.  Should only be called at GC boundaries, since

  // some unused space may be used as scratch space during GC's.

  // Default implementation does nothing. We also call this when expanding

  // a space to satisfy an allocation request. See bug #4668531

  virtual void mangle_unused_area() {}

  virtual void mangle_unused_area_complete() {}

  virtual void mangle_region(MemRegion mr) {}

  // Testers

  bool is_empty() const              { return used() == 0; }

  bool not_empty() const             { return used() > 0; }

  // Returns true iff the given the space contains the

  // given address as part of an allocated object. For

  // certain kinds of spaces, this might be a potentially

  // expensive operation. To prevent performance problems

  // on account of its inadvertent use in product jvm's,

  // we restrict its use to assertion checks only.

  bool is_in(const void* p) const {

    return used_region().contains(p);

  }

  // Returns true iff the given reserved memory of the space contains the

  // given address.

  bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; }

  // Returns true iff the given block is not allocated.

  virtual bool is_free_block(const HeapWord* p) const = 0;

  // Test whether p is double-aligned

  static bool is_aligned(void* p) {

    return ((intptr_t)p & (sizeof(double)-1)) == 0;

  }

  // Size computations.  Sizes are in bytes.

  size_t capacity()     const { return byte_size(bottom(), end()); }

  virtual size_t used() const = 0;

  virtual size_t free() const = 0;

  // Iterate over all the ref-containing fields of all objects in the

  // space, calling "cl.do_oop" on each.  Fields in objects allocated by

  // applications of the closure are not included in the iteration.

  virtual void oop_iterate(ExtendedOopClosure* cl);

  // Iterate over all objects in the space, calling "cl.do_object" on

  // each.  Objects allocated by applications of the closure are not

  // included in the iteration.

  virtual void object_iterate(ObjectClosure* blk) = 0;

  // Similar to object_iterate() except only iterates over

  // objects whose internal references point to objects in the space.

  virtual void safe_object_iterate(ObjectClosure* blk) = 0;

  // Create and return a new dirty card to oop closure. Can be

  // overridden to return the appropriate type of closure

  // depending on the type of space in which the closure will

  // operate. ResourceArea allocated.

  virtual DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,

                                             CardTableModRefBS::PrecisionStyle precision,

                                             HeapWord* boundary = NULL);

  // If "p" is in the space, returns the address of the start of the

  // "block" that contains "p".  We say "block" instead of "object" since

  // some heaps may not pack objects densely; a chunk may either be an

  // object or a non-object.  If "p" is not in the space, return NULL.

  virtual HeapWord* block_start_const(const void* p) const = 0;

  // The non-const version may have benevolent side effects on the data

  // structure supporting these calls, possibly speeding up future calls.

  // The default implementation, however, is simply to call the const

  // version.

  inline virtual HeapWord* block_start(const void* p);

  // Requires "addr" to be the start of a chunk, and returns its size.

  // "addr + size" is required to be the start of a new chunk, or the end

  // of the active area of the heap.

  virtual size_t block_size(const HeapWord* addr) const = 0;

  // Requires "addr" to be the start of a block, and returns "TRUE" iff

  // the block is an object.

  virtual bool block_is_obj(const HeapWord* addr) const = 0;

  // Requires "addr" to be the start of a block, and returns "TRUE" iff

  // the block is an object and the object is alive.

  virtual bool obj_is_alive(const HeapWord* addr) const;

  // Allocation (return NULL if full).  Assumes the caller has established

  // mutually exclusive access to the space.

  virtual HeapWord* allocate(size_t word_size) = 0;

  // Allocation (return NULL if full).  Enforces mutual exclusion internally.

  virtual HeapWord* par_allocate(size_t word_size) = 0;

  // Mark-sweep-compact support: all spaces can update pointers to objects

  // moving as a part of compaction.

  virtual void adjust_pointers();

  // PrintHeapAtGC support

  virtual void print() const;

  virtual void print_on(outputStream* st) const;

  virtual void print_short() const;

  virtual void print_short_on(outputStream* st) const;

  // Accessor for parallel sequential tasks.

  SequentialSubTasksDone* par_seq_tasks() { return &_par_seq_tasks; }

  // IF "this" is a ContiguousSpace, return it, else return NULL.

  virtual ContiguousSpace* toContiguousSpace() {

    return NULL;

  }

  // Debugging

  virtual void verify() const = 0;

};

// A MemRegionClosure (ResourceObj) whose "do_MemRegion" function applies an

// OopClosure to (the addresses of) all the ref-containing fields that could

// be modified by virtue of the given MemRegion being dirty. (Note that

// because of the imprecise nature of the write barrier, this may iterate

// over oops beyond the region.)

// This base type for dirty card to oop closures handles memory regions

// in non-contiguous spaces with no boundaries, and should be sub-classed

// to support other space types. See ContiguousDCTOC for a sub-class

// that works with ContiguousSpaces.

class DirtyCardToOopClosure: public MemRegionClosureRO {

protected:

  ExtendedOopClosure* _cl;

  Space* _sp;

  CardTableModRefBS::PrecisionStyle _precision;

  HeapWord* _boundary;          // If non-NULL, process only non-NULL oops

                                // pointing below boundary.

  HeapWord* _min_done;          // ObjHeadPreciseArray precision requires

                                // a downwards traversal; this is the

                                // lowest location already done (or,

                                // alternatively, the lowest address that

                                // shouldn't be done again.  NULL means infinity.)

  NOT_PRODUCT(HeapWord* _last_bottom;)

  NOT_PRODUCT(HeapWord* _last_explicit_min_done;)

  // Get the actual top of the area on which the closure will

  // operate, given where the top is assumed to be (the end of the

  // memory region passed to do_MemRegion) and where the object

  // at the top is assumed to start. For example, an object may

  // start at the top but actually extend past the assumed top,

  // in which case the top becomes the end of the object.

  virtual HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);

  // Walk the given memory region from bottom to (actual) top

  // looking for objects and applying the oop closure (_cl) to

  // them. The base implementation of this treats the area as

  // blocks, where a block may or may not be an object. Sub-

  // classes should override this to provide more accurate

  // or possibly more efficient walking.

  virtual void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);

public:

  DirtyCardToOopClosure(Space* sp, ExtendedOopClosure* cl,

                        CardTableModRefBS::PrecisionStyle precision,

                        HeapWord* boundary) :

    _sp(sp), _cl(cl), _precision(precision), _boundary(boundary),

    _min_done(NULL) {

    NOT_PRODUCT(_last_bottom = NULL);

    NOT_PRODUCT(_last_explicit_min_done = NULL);

  }

  void do_MemRegion(MemRegion mr);

  void set_min_done(HeapWord* min_done) {

    _min_done = min_done;

    NOT_PRODUCT(_last_explicit_min_done = _min_done);

  }

#ifndef PRODUCT

  void set_last_bottom(HeapWord* last_bottom) {

    _last_bottom = last_bottom;

  }

#endif

};

// A structure to represent a point at which objects are being copied

// during compaction.

class CompactPoint : public StackObj {

public:

  Generation* gen;

  CompactibleSpace* space;

  HeapWord* threshold;

  CompactPoint(Generation* _gen) :

    gen(_gen), space(NULL), threshold(0) {}

};

// A space that supports compaction operations.  This is usually, but not

// necessarily, a space that is normally contiguous.  But, for example, a

// free-list-based space whose normal collection is a mark-sweep without

// compaction could still support compaction in full GC's.

class CompactibleSpace: public Space {

  friend class VMStructs;

  friend class CompactibleFreeListSpace;

private:

  HeapWord* _compaction_top;

  CompactibleSpace* _next_compaction_space;

public:

  CompactibleSpace() :

   _compaction_top(NULL), _next_compaction_space(NULL) {}

  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);

  virtual void clear(bool mangle_space);

  // Used temporarily during a compaction phase to hold the value

  // top should have when compaction is complete.

  HeapWord* compaction_top() const { return _compaction_top;    }

  void set_compaction_top(HeapWord* value) {

    assert(value == NULL || (value >= bottom() && value <= end()),

      "should point inside space");

    _compaction_top = value;

  }

  // Perform operations on the space needed after a compaction

  // has been performed.

  virtual void reset_after_compaction() = 0;

  // Returns the next space (in the current generation) to be compacted in

  // the global compaction order.  Also is used to select the next

  // space into which to compact.

  virtual CompactibleSpace* next_compaction_space() const {

    return _next_compaction_space;

  }

  void set_next_compaction_space(CompactibleSpace* csp) {

    _next_compaction_space = csp;

  }

  // MarkSweep support phase2

  // Start the process of compaction of the current space: compute

  // post-compaction addresses, and insert forwarding pointers.  The fields

  // "cp->gen" and "cp->compaction_space" are the generation and space into

  // which we are currently compacting.  This call updates "cp" as necessary,

  // and leaves the "compaction_top" of the final value of

  // "cp->compaction_space" up-to-date.  Offset tables may be updated in

  // this phase as if the final copy had occurred; if so, "cp->threshold"

  // indicates when the next such action should be taken.

  virtual void prepare_for_compaction(CompactPoint* cp);

  // MarkSweep support phase3

  virtual void adjust_pointers();

  // MarkSweep support phase4

  virtual void compact();

  // The maximum percentage of objects that can be dead in the compacted

  // live part of a compacted space ("deadwood" support.)

  virtual size_t allowed_dead_ratio() const { return 0; };

  // Some contiguous spaces may maintain some data structures that should

  // be updated whenever an allocation crosses a boundary.  This function

  // returns the first such boundary.

  // (The default implementation returns the end of the space, so the

  // boundary is never crossed.)

  virtual HeapWord* initialize_threshold() { return end(); }

  // "q" is an object of the given "size" that should be forwarded;

  // "cp" names the generation ("gen") and containing "this" (which must

  // also equal "cp->space").  "compact_top" is where in "this" the

  // next object should be forwarded to.  If there is room in "this" for

  // the object, insert an appropriate forwarding pointer in "q".

  // If not, go to the next compaction space (there must

  // be one, since compaction must succeed -- we go to the first space of

  // the previous generation if necessary, updating "cp"), reset compact_top

  // and then forward.  In either case, returns the new value of "compact_top".

  // If the forwarding crosses "cp->threshold", invokes the "cross_threshold"

  // function of the then-current compaction space, and updates "cp->threshold

  // accordingly".

  virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp,

                    HeapWord* compact_top);

  // Return a size with adjustments as required of the space.

  virtual size_t adjust_object_size_v(size_t size) const { return size; }

protected:

  // Used during compaction.

  HeapWord* _first_dead;

  HeapWord* _end_of_live;

  // Minimum size of a free block.

  virtual size_t minimum_free_block_size() const { return 0; }

  // This the function is invoked when an allocation of an object covering

  // "start" to "end occurs crosses the threshold; returns the next

  // threshold.  (The default implementation does nothing.)

  virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* the_end) {

    return end();

  }

  // Requires "allowed_deadspace_words > 0", that "q" is the start of a

  // free block of the given "word_len", and that "q", were it an object,

  // would not move if forwarded.  If the size allows, fill the free

  // block with an object, to prevent excessive compaction.  Returns "true"

  // iff the free region was made deadspace, and modifies

  // "allowed_deadspace_words" to reflect the number of available deadspace

  // words remaining after this operation.

  bool insert_deadspace(size_t& allowed_deadspace_words, HeapWord* q,

                        size_t word_len);

};

class GenSpaceMangler;

// A space in which the free area is contiguous.  It therefore supports

// faster allocation, and compaction.

class ContiguousSpace: public CompactibleSpace {

  friend class OneContigSpaceCardGeneration;

  friend class VMStructs;

 protected:

  HeapWord* _top;

  HeapWord* _concurrent_iteration_safe_limit;

  // A helper for mangling the unused area of the space in debug builds.

  GenSpaceMangler* _mangler;

  GenSpaceMangler* mangler() { return _mangler; }

  // Allocation helpers (return NULL if full).

  inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);

  inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);

 public:

  ContiguousSpace();

  ~ContiguousSpace();

  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);

  virtual void clear(bool mangle_space);

  // Accessors

  HeapWord* top() const            { return _top;    }

  void set_top(HeapWord* value)    { _top = value; }

  void set_saved_mark()            { _saved_mark_word = top();    }

  void reset_saved_mark()          { _saved_mark_word = bottom(); }

  WaterMark bottom_mark()     { return WaterMark(this, bottom()); }

  WaterMark top_mark()        { return WaterMark(this, top()); }

  WaterMark saved_mark()      { return WaterMark(this, saved_mark_word()); }

  bool saved_mark_at_top() const { return saved_mark_word() == top(); }

  // In debug mode mangle (write it with a particular bit

  // pattern) the unused part of a space.

  // Used to save the an address in a space for later use during mangling.

  void set_top_for_allocations(HeapWord* v) PRODUCT_RETURN;

  // Used to save the space's current top for later use during mangling.

  void set_top_for_allocations() PRODUCT_RETURN;

  // Mangle regions in the space from the current top up to the

  // previously mangled part of the space.

  void mangle_unused_area() PRODUCT_RETURN;

  // Mangle [top, end)

  void mangle_unused_area_complete() PRODUCT_RETURN;

  // Mangle the given MemRegion.

  void mangle_region(MemRegion mr) PRODUCT_RETURN;

  // Do some sparse checking on the area that should have been mangled.

  void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;

  // Check the complete area that should have been mangled.

  // This code may be NULL depending on the macro DEBUG_MANGLING.

  void check_mangled_unused_area_complete() PRODUCT_RETURN;

  // Size computations: sizes in bytes.