| /* |
| * Copyright (c) 1997, 2018, 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_SHARED_SPACE_HPP |
| #define SHARE_VM_GC_SHARED_SPACE_HPP |
| |
| #include "gc/shared/blockOffsetTable.hpp" |
| #include "gc/shared/cardTable.hpp" |
| #include "gc/shared/workgroup.hpp" |
| #include "memory/allocation.hpp" |
| #include "memory/iterator.hpp" |
| #include "memory/memRegion.hpp" |
| #include "oops/markOop.hpp" |
| #include "runtime/mutexLocker.hpp" |
| #include "utilities/align.hpp" |
| #include "utilities/macros.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. |
| |
| // Forward decls. |
| class Space; |
| class BlockOffsetArray; |
| class BlockOffsetArrayContigSpace; |
| class Generation; |
| class CompactibleSpace; |
| class BlockOffsetTable; |
| 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; |
| |
| // 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) { } |
| |
| 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(); |
| } |
| |
| virtual MemRegionClosure* preconsumptionDirtyCardClosure() const { |
| return NULL; |
| } |
| |
| // 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. |
| // We also call this when expanding a space to satisfy an allocation |
| // request. See bug #4668531 |
| virtual void mangle_unused_area() = 0; |
| virtual void mangle_unused_area_complete() = 0; |
| |
| // 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); |
| } |
| bool is_in(oop obj) const { |
| return is_in((void*)obj); |
| } |
| |
| // 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 ::is_aligned(p, sizeof(double)); |
| } |
| |
| // 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(OopIterateClosure* 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(OopIterateClosure* cl, |
| CardTable::PrecisionStyle precision, |
| HeapWord* boundary, |
| bool parallel); |
| |
| // 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. |
| 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; |
| |
| #if INCLUDE_SERIALGC |
| // Mark-sweep-compact support: all spaces can update pointers to objects |
| // moving as a part of compaction. |
| virtual void adjust_pointers() = 0; |
| #endif |
| |
| 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: |
| OopIterateClosure* _cl; |
| Space* _sp; |
| CardTable::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, OopIterateClosure* cl, |
| CardTable::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* g = NULL) : |
| gen(g), 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. |
| // |
| // The compaction operations are implemented by the |
| // scan_and_{adjust_pointers,compact,forward} function templates. |
| // The following are, non-virtual, auxiliary functions used by these function templates: |
| // - scan_limit() |
| // - scanned_block_is_obj() |
| // - scanned_block_size() |
| // - adjust_obj_size() |
| // - obj_size() |
| // These functions are to be used exclusively by the scan_and_* function templates, |
| // and must be defined for all (non-abstract) subclasses of CompactibleSpace. |
| // |
| // NOTE: Any subclasses to CompactibleSpace wanting to change/define the behavior |
| // in any of the auxiliary functions must also override the corresponding |
| // prepare_for_compaction/adjust_pointers/compact functions using them. |
| // If not, such changes will not be used or have no effect on the compaction operations. |
| // |
| // This translates to the following dependencies: |
| // Overrides/definitions of |
| // - scan_limit |
| // - scanned_block_is_obj |
| // - scanned_block_size |
| // require override/definition of prepare_for_compaction(). |
| // Similar dependencies exist between |
| // - adjust_obj_size and adjust_pointers() |
| // - obj_size and compact(). |
| // |
| // Additionally, this also means that changes to block_size() or block_is_obj() that |
| // should be effective during the compaction operations must provide a corresponding |
| // definition of scanned_block_size/scanned_block_is_obj respectively. |
| class CompactibleSpace: public Space { |
| friend class VMStructs; |
| friend class CompactibleFreeListSpace; |
| private: |
| HeapWord* _compaction_top; |
| CompactibleSpace* _next_compaction_space; |
| |
| // Auxiliary functions for scan_and_{forward,adjust_pointers,compact} support. |
| inline size_t adjust_obj_size(size_t size) const { |
| return size; |
| } |
| |
| inline size_t obj_size(const HeapWord* addr) const; |
| |
| template <class SpaceType> |
| static inline void verify_up_to_first_dead(SpaceType* space) NOT_DEBUG_RETURN; |
| |
| template <class SpaceType> |
| static inline void clear_empty_region(SpaceType* 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; |
| } |
| |
| #if INCLUDE_SERIALGC |
| // 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) = 0; |
| // MarkSweep support phase3 |
| virtual void adjust_pointers(); |
| // MarkSweep support phase4 |
| virtual void compact(); |
| #endif // INCLUDE_SERIALGC |
| |
| // 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; } |
| |
| void set_first_dead(HeapWord* value) { _first_dead = value; } |
| void set_end_of_live(HeapWord* value) { _end_of_live = value; } |
| |
| 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(); |
| } |
| |
| // Below are template functions for scan_and_* algorithms (avoiding virtual calls). |
| // The space argument should be a subclass of CompactibleSpace, implementing |
| // scan_limit(), scanned_block_is_obj(), and scanned_block_size(), |
| // and possibly also overriding obj_size(), and adjust_obj_size(). |
| // These functions should avoid virtual calls whenever possible. |
| |
| #if INCLUDE_SERIALGC |
| // Frequently calls adjust_obj_size(). |
| template <class SpaceType> |
| static inline void scan_and_adjust_pointers(SpaceType* space); |
| #endif |
| |
| // Frequently calls obj_size(). |
| template <class SpaceType> |
| static inline void scan_and_compact(SpaceType* space); |
| |
| // Frequently calls scanned_block_is_obj() and scanned_block_size(). |
| // Requires the scan_limit() function. |
| template <class SpaceType> |
| static inline void scan_and_forward(SpaceType* space, CompactPoint* cp); |
| }; |
| |
| class GenSpaceMangler; |
| |
| // A space in which the free area is contiguous. It therefore supports |
| // faster allocation, and compaction. |
| class ContiguousSpace: public CompactibleSpace { |
| friend class VMStructs; |
| // Allow scan_and_forward function to call (private) overrides for auxiliary functions on this class |
| template <typename SpaceType> |
| friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp); |
| |
| private: |
| // Auxiliary functions for scan_and_forward support. |
| // See comments for CompactibleSpace for more information. |
| inline HeapWord* scan_limit() const { |
| return top(); |
| } |
| |
| inline bool scanned_block_is_obj(const HeapWord* addr) const { |
| return true; // Always true, since scan_limit is top |
| } |
| |
| inline size_t scanned_block_size(const HeapWord* addr) const; |
| |
| 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); |
| inline HeapWord* par_allocate_impl(size_t word_size); |
| |
| 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(); } |
| |
| 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; |
| |
| // 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); |
| HeapWord* allocate_aligned(size_t word_size); |
| |
| // Iteration |
| void oop_iterate(OopIterateClosure* 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; |
| } |
| |
| // In support of parallel oop_iterate. |
| template <typename OopClosureType> |
| void par_oop_iterate(MemRegion mr, OopClosureType* blk); |
| |
| // 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(OopIterateClosure* cl, |
| CardTable::PrecisionStyle precision, |
| HeapWord* boundary, |
| bool parallel); |
| |
| // 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. |
| template <typename OopClosureType> |
| void oop_since_save_marks_iterate(OopClosureType* blk); |
| |
| // 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(HeapWord* 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; } |
| |
| #if INCLUDE_SERIALGC |
| // Overrides for more efficient compaction support. |
| void prepare_for_compaction(CompactPoint* cp); |
| #endif |
| |
| 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 FilteringDCTOC : 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, |
| OopIterateClosure* cl) = 0; |
| virtual void walk_mem_region_with_cl(MemRegion mr, |
| HeapWord* bottom, HeapWord* top, |
| FilteringClosure* cl) = 0; |
| |
| public: |
| FilteringDCTOC(Space* sp, OopIterateClosure* cl, |
| CardTable::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 FilteringDCTOC { |
| protected: |
| // Overrides. |
| HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj); |
| |
| virtual void walk_mem_region_with_cl(MemRegion mr, |
| HeapWord* bottom, HeapWord* top, |
| OopIterateClosure* cl); |
| virtual void walk_mem_region_with_cl(MemRegion mr, |
| HeapWord* bottom, HeapWord* top, |
| FilteringClosure* cl); |
| |
| public: |
| ContiguousSpaceDCTOC(ContiguousSpace* sp, OopIterateClosure* cl, |
| CardTable::PrecisionStyle precision, |
| HeapWord* boundary) : |
| FilteringDCTOC(sp, cl, precision, boundary) |
| {} |
| }; |
| |
| // 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_GC_SHARED_SPACE_HPP |