|
/*
* Copyright (c) 1997, 2022, 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_GC_SHARED_SPACE_HPP
#define SHARE_GC_SHARED_SPACE_HPP
#include "gc/shared/blockOffsetTable.hpp"
#include "gc/shared/cardTable.hpp"
#include "gc/shared/workerThread.hpp"
#include "memory/allocation.hpp"
#include "memory/iterator.hpp"
#include "memory/memRegion.hpp"
#include "oops/markWord.hpp"
#include "runtime/mutexLocker.hpp"
#include "utilities/align.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_SERIALGC
#include "gc/serial/serialBlockOffsetTable.hpp"
#endif
// 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 ContiguousSpace;
#if INCLUDE_SERIALGC
class BlockOffsetArray;
class BlockOffsetArrayContigSpace;
class BlockOffsetTable;
#endif
class Generation;
class CompactibleSpace;
class CardTableRS;
class DirtyCardToOopClosure;
class FilteringClosure;
// 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;
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 cast_from_oop<HeapWord*>(obj) >= saved_mark_word();
}
// 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; }
// 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;
// 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);
// 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;
// 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;)
// 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) :
_cl(cl), _sp(sp), _precision(precision), _boundary(boundary),
_min_done(NULL) {
NOT_PRODUCT(_last_bottom = NULL);
}
void do_MemRegion(MemRegion mr) override;
};
// A structure to represent a point at which objects are being copied
// during compaction.
class CompactPoint : public StackObj {
public:
Generation* gen;
CompactibleSpace* space;
CompactPoint(Generation* g = NULL) :
gen(g), space(NULL) {}
};
// 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;
private:
HeapWord* _compaction_top;
CompactibleSpace* _next_compaction_space;
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) {}
void initialize(MemRegion mr, bool clear_space, bool mangle_space) override;
void clear(bool mangle_space) override;
// 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
void adjust_pointers() override;
// 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
// initializes these data structures for further updates.
virtual void initialize_threshold() { }
// "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".
// Invokes the "alloc_block" function of the then-current compaction
// space.
virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp,
HeapWord* compact_top);
protected:
// Used during compaction.
HeapWord* _first_dead;
HeapWord* _end_of_live;
// This the function to invoke when an allocation of an object covering
// "start" to "end" occurs to update other internal data structures.
virtual void alloc_block(HeapWord* start, HeapWord* the_end) { }
};
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;
protected:
HeapWord* _top;
// 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();
void initialize(MemRegion mr, bool clear_space, bool mangle_space) override;
void clear(bool mangle_space) override;
// 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 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() override PRODUCT_RETURN;
// Mangle [top, end)
void mangle_unused_area_complete() override 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 used() const override { return byte_size(bottom(), top()); }
size_t free() const override { return byte_size(top(), end()); }
bool is_free_block(const HeapWord* p) const override;
// In a contiguous space we have a more obvious bound on what parts
// contain objects.
MemRegion used_region() const override { return MemRegion(bottom(), top()); }
// Allocation (return NULL if full)
HeapWord* allocate(size_t word_size) override;
HeapWord* par_allocate(size_t word_size) override;
// Iteration
void oop_iterate(OopIterateClosure* cl) override;
void object_iterate(ObjectClosure* blk) override;
// Compaction support
void reset_after_compaction() override {
assert(compaction_top() >= bottom() && compaction_top() <= end(), "should point inside space");
set_top(compaction_top());
}
// Override.
DirtyCardToOopClosure* new_dcto_cl(OopIterateClosure* cl,
CardTable::PrecisionStyle precision,
HeapWord* boundary) override;
// 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.
HeapWord* block_start_const(const void* p) const override;
size_t block_size(const HeapWord* p) const override;
// If a block is in the allocated area, it is an object.
bool block_is_obj(const HeapWord* p) const override { 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) override;
#endif
void print_on(outputStream* st) const override;
// Checked dynamic downcasts.
ContiguousSpace* toContiguousSpace() override {
return this;
}
// Debugging
void verify() const override;
};
// A dirty card to oop closure for contiguous spaces (ContiguousSpace and
// sub-classes). It knows how to filter out objects that are outside of the
// _boundary.
//
// Assumptions:
// 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 DirtyCardToOopClosure {
// Overrides.
void walk_mem_region(MemRegion mr,
HeapWord* bottom, HeapWord* top) override;
HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj) override;
// 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.
void walk_mem_region_with_cl(MemRegion mr,
HeapWord* bottom, HeapWord* top,
OopIterateClosure* cl);
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) :
DirtyCardToOopClosure(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.
#if INCLUDE_SERIALGC
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) override;
void set_end(HeapWord* value) override;
void clear(bool mangle_space) override;
inline HeapWord* block_start_const(const void* p) const override;
// Add offset table update.
inline HeapWord* allocate(size_t word_size) override;
inline HeapWord* par_allocate(size_t word_size) override;
// MarkSweep support phase3
void initialize_threshold() override;
void alloc_block(HeapWord* start, HeapWord* end) override;
void print_on(outputStream* st) const override;
// Debugging
void verify() const override;
};
// Class TenuredSpace is used by TenuredGeneration
class TenuredSpace: public OffsetTableContigSpace {
friend class VMStructs;
protected:
// Mark sweep support
size_t allowed_dead_ratio() const override;
public:
// Constructor
TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray,
MemRegion mr) :
OffsetTableContigSpace(sharedOffsetArray, mr) {}
};
#endif //INCLUDE_SERIALGC
#endif // SHARE_GC_SHARED_SPACE_HPP
¤ Dauer der Verarbeitung: 0.21 Sekunden
(vorverarbeitet)
¤
|
Haftungshinweis
Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.
Bemerkung:
Die farbliche Syntaxdarstellung ist noch experimentell.
|
