jdk8-mips64-public/hotspot: src/share/vm/memory/space.hpp@3f2894c5052e (annotated)

src/share/vm/memory/space.hpp@3f2894c5052e (annotated)

src/share/vm/memory/space.hpp

Mon, 21 Jul 2014 10:00:31 +0200

author: tschatzl
date: Mon, 21 Jul 2014 10:00:31 +0200
changeset 7009: 3f2894c5052e
parent 6981: ff1e37e7eb83
child 7031: ee019285a52c
permissions: -rw-r--r--

8048112: G1 Full GC needs to support the case when the very first region is not available
Summary: Refactor preparation for compaction during Full GC so that it lazily initializes the first compaction point. This also avoids problems later when the first region may not be committed. Also reviewed by K. Barrett.
Reviewed-by: brutisso

 /*
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  * 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
  * or visit www.oracle.com if you need additional information or have any
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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 asbtract 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 distiguish 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
   // ceratin 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
   // overriden 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_threhold"
   // 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 adjusments 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 forwared.  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.
   size_t capacity() const        { return byte_size(bottom(), end()); }
   size_t used() const            { return byte_size(bottom(), top()); }
   size_t free() const            { return byte_size(top(),    end()); }
   virtual bool is_free_block(const HeapWord* p) const;
   // In a contiguous space we have a more obvious bound on what parts
   // contain objects.
   MemRegion used_region() const { return MemRegion(bottom(), top()); }
   // Allocation (return NULL if full)
   virtual HeapWord* allocate(size_t word_size);
   virtual HeapWord* par_allocate(size_t word_size);
   // Iteration
   void oop_iterate(ExtendedOopClosure* cl);
   void object_iterate(ObjectClosure* blk);
   // For contiguous spaces this method will iterate safely over objects
   // in the space (i.e., between bottom and top) when at a safepoint.
   void safe_object_iterate(ObjectClosure* blk);
   // Iterate over as many initialized objects in the space as possible,
   // calling "cl.do_object_careful" on each. Return NULL if all objects
   // in the space (at the start of the iteration) were iterated over.
   // Return an address indicating the extent of the iteration in the
   // event that the iteration had to return because of finding an
   // uninitialized object in the space, or if the closure "cl"
   // signaled early termination.
   HeapWord* object_iterate_careful(ObjectClosureCareful* cl);
   HeapWord* concurrent_iteration_safe_limit() {
     assert(_concurrent_iteration_safe_limit <= top(),
            "_concurrent_iteration_safe_limit update missed");
     return _concurrent_iteration_safe_limit;
   }
   // changes the safe limit, all objects from bottom() to the new
   // limit should be properly initialized
   void set_concurrent_iteration_safe_limit(HeapWord* new_limit) {
     assert(new_limit <= top(), "uninitialized objects in the safe range");
     _concurrent_iteration_safe_limit = new_limit;
   }
 #if INCLUDE_ALL_GCS
   // In support of parallel oop_iterate.
   #define ContigSpace_PAR_OOP_ITERATE_DECL(OopClosureType, nv_suffix)  \
     void par_oop_iterate(MemRegion mr, OopClosureType* blk);
     ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DECL)
   #undef ContigSpace_PAR_OOP_ITERATE_DECL
 #endif // INCLUDE_ALL_GCS
   // Compaction support
   virtual void reset_after_compaction() {
     assert(compaction_top() >= bottom() && compaction_top() <= end(), "should point inside space");
     set_top(compaction_top());
     // set new iteration safe limit
     set_concurrent_iteration_safe_limit(compaction_top());
   }
   // Override.
   DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,
                                      CardTableModRefBS::PrecisionStyle precision,
                                      HeapWord* boundary = NULL);
   // Apply "blk->do_oop" to the addresses of all reference fields in objects
   // starting with the _saved_mark_word, which was noted during a generation's
   // save_marks and is required to denote the head of an object.
   // Fields in objects allocated by applications of the closure
   // *are* included in the iteration.
   // Updates _saved_mark_word to point to just after the last object
   // iterated over.
 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)  \
   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk);
   ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DECL)
 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DECL
   // Same as object_iterate, but starting from "mark", which is required
   // to denote the start of an object.  Objects allocated by
   // applications of the closure *are* included in the iteration.
   virtual void object_iterate_from(WaterMark mark, ObjectClosure* blk);
   // Very inefficient implementation.
   virtual HeapWord* block_start_const(const void* p) const;
   size_t block_size(const HeapWord* p) const;
   // If a block is in the allocated area, it is an object.
   bool block_is_obj(const HeapWord* p) const { return p < top(); }
   // Addresses for inlined allocation
   HeapWord** top_addr() { return &_top; }
   HeapWord** end_addr() { return &_end; }
   // Overrides for more efficient compaction support.
   void prepare_for_compaction(CompactPoint* cp);
   // PrintHeapAtGC support.
   virtual void print_on(outputStream* st) const;
   // Checked dynamic downcasts.
   virtual ContiguousSpace* toContiguousSpace() {
     return this;
   }
   // Debugging
   virtual void verify() const;
   // Used to increase collection frequency.  "factor" of 0 means entire
   // space.
   void allocate_temporary_filler(int factor);
 };
 // A dirty card to oop closure that does filtering.
 // It knows how to filter out objects that are outside of the _boundary.
 class Filtering_DCTOC : public DirtyCardToOopClosure {
 protected:
   // Override.
   void walk_mem_region(MemRegion mr,
                        HeapWord* bottom, HeapWord* top);
   // Walk the given memory region, from bottom to top, applying
   // the given oop closure to (possibly) all objects found. The
   // given oop closure may or may not be the same as the oop
   // closure with which this closure was created, as it may
   // be a filtering closure which makes use of the _boundary.
   // We offer two signatures, so the FilteringClosure static type is
   // apparent.
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        ExtendedOopClosure* cl) = 0;
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        FilteringClosure* cl) = 0;
 public:
   Filtering_DCTOC(Space* sp, ExtendedOopClosure* cl,
                   CardTableModRefBS::PrecisionStyle precision,
                   HeapWord* boundary) :
     DirtyCardToOopClosure(sp, cl, precision, boundary) {}
 };
 // A dirty card to oop closure for contiguous spaces
 // (ContiguousSpace and sub-classes).
 // It is a FilteringClosure, as defined above, and it knows:
 //
 // 1. That the actual top of any area in a memory region
 //    contained by the space is bounded by the end of the contiguous
 //    region of the space.
 // 2. That the space is really made up of objects and not just
 //    blocks.
 class ContiguousSpaceDCTOC : public Filtering_DCTOC {
 protected:
   // Overrides.
   HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        ExtendedOopClosure* cl);
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        FilteringClosure* cl);
 public:
   ContiguousSpaceDCTOC(ContiguousSpace* sp, ExtendedOopClosure* cl,
                        CardTableModRefBS::PrecisionStyle precision,
                        HeapWord* boundary) :
     Filtering_DCTOC(sp, cl, precision, boundary)
   {}
 };
 // Class EdenSpace describes eden-space in new generation.
 class DefNewGeneration;
 class EdenSpace : public ContiguousSpace {
   friend class VMStructs;
  private:
   DefNewGeneration* _gen;
   // _soft_end is used as a soft limit on allocation.  As soft limits are
   // reached, the slow-path allocation code can invoke other actions and then
   // adjust _soft_end up to a new soft limit or to end().
   HeapWord* _soft_end;
  public:
   EdenSpace(DefNewGeneration* gen) :
    _gen(gen), _soft_end(NULL) {}
   // Get/set just the 'soft' limit.
   HeapWord* soft_end()               { return _soft_end; }
   HeapWord** soft_end_addr()         { return &_soft_end; }
   void set_soft_end(HeapWord* value) { _soft_end = value; }
   // Override.
   void clear(bool mangle_space);
   // Set both the 'hard' and 'soft' limits (_end and _soft_end).
   void set_end(HeapWord* value) {
     set_soft_end(value);
     ContiguousSpace::set_end(value);
   }
   // Allocation (return NULL if full)
   HeapWord* allocate(size_t word_size);
   HeapWord* par_allocate(size_t word_size);
 };
 // Class ConcEdenSpace extends EdenSpace for the sake of safe
 // allocation while soft-end is being modified concurrently
 class ConcEdenSpace : public EdenSpace {
  public:
   ConcEdenSpace(DefNewGeneration* gen) : EdenSpace(gen) { }
   // Allocation (return NULL if full)
   HeapWord* par_allocate(size_t word_size);
 };
 // A ContigSpace that Supports an efficient "block_start" operation via
 // a BlockOffsetArray (whose BlockOffsetSharedArray may be shared with
 // other spaces.)  This is the abstract base class for old generation
 // (tenured) spaces.
 class OffsetTableContigSpace: public ContiguousSpace {
   friend class VMStructs;
  protected:
   BlockOffsetArrayContigSpace _offsets;
   Mutex _par_alloc_lock;
  public:
   // Constructor
   OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
                          MemRegion mr);
   void set_bottom(HeapWord* value);
   void set_end(HeapWord* value);
   void clear(bool mangle_space);
   inline HeapWord* block_start_const(const void* p) const;
   // Add offset table update.
   virtual inline HeapWord* allocate(size_t word_size);
   inline HeapWord* par_allocate(size_t word_size);
   // MarkSweep support phase3
   virtual HeapWord* initialize_threshold();
   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
   virtual void print_on(outputStream* st) const;
   // Debugging
   void verify() const;
 };
 // Class TenuredSpace is used by TenuredGeneration
 class TenuredSpace: public OffsetTableContigSpace {
   friend class VMStructs;
  protected:
   // Mark sweep support
   size_t allowed_dead_ratio() const;
  public:
   // Constructor
   TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray,
                MemRegion mr) :
     OffsetTableContigSpace(sharedOffsetArray, mr) {}
 };
 #endif // SHARE_VM_MEMORY_SPACE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/space.hpp@3f2894c5052e (annotated)

src/share/vm/memory/space.hpp