--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/shared/space.hpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,792 @@
+/*
+ * Copyright (c) 1997, 2015, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_SPACE_HPP
+#define SHARE_VM_GC_SHARED_SPACE_HPP
+
+#include "gc/shared/blockOffsetTable.hpp"
+#include "gc/shared/cardTableModRefBS.hpp"
+#include "gc/shared/watermark.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/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 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;
+
+ // 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);
+ }
+
+ // 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.
+ 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() = 0;
+
+ // 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* 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 {
+ return oop(addr)->size();
+ }
+
+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) = 0;
+ // 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);
+
+ // 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.
+
+ // Frequently calls adjust_obj_size().
+ template <class SpaceType>
+ static inline void scan_and_adjust_pointers(SpaceType* space);
+
+ // 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 {
+ return oop(addr)->size();
+ }
+
+ 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(); }
+
+ 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;
+
+ // 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(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)
+ {}
+};
+
+// 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