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src/share/vm/memory/space.hpp@6aae2f9d0294 (annotated)

src/share/vm/memory/space.hpp

Thu, 12 Jun 2008 13:50:55 -0700

author

ysr

date

Thu, 12 Jun 2008 13:50:55 -0700

changeset 779

6aae2f9d0294

parent 777

37f87013dfd8

child 782

60fb9c4db4e6

permissions

-rw-r--r--

Merge

duke@435	1	/*
duke@435	2	* Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	// A space is an abstraction for the "storage units" backing
duke@435	26	// up the generation abstraction. It includes specific
duke@435	27	// implementations for keeping track of free and used space,
duke@435	28	// for iterating over objects and free blocks, etc.
duke@435	29
duke@435	30	// Here's the Space hierarchy:
duke@435	31	//
duke@435	32	// - Space -- an asbtract base class describing a heap area
duke@435	33	// - CompactibleSpace -- a space supporting compaction
duke@435	34	// - CompactibleFreeListSpace -- (used for CMS generation)
duke@435	35	// - ContiguousSpace -- a compactible space in which all free space
duke@435	36	// is contiguous
duke@435	37	// - EdenSpace -- contiguous space used as nursery
duke@435	38	// - ConcEdenSpace -- contiguous space with a 'soft end safe' allocation
duke@435	39	// - OffsetTableContigSpace -- contiguous space with a block offset array
duke@435	40	// that allows "fast" block_start calls
duke@435	41	// - TenuredSpace -- (used for TenuredGeneration)
duke@435	42	// - ContigPermSpace -- an offset table contiguous space for perm gen
duke@435	43
duke@435	44	// Forward decls.
duke@435	45	class Space;
duke@435	46	class BlockOffsetArray;
duke@435	47	class BlockOffsetArrayContigSpace;
duke@435	48	class Generation;
duke@435	49	class CompactibleSpace;
duke@435	50	class BlockOffsetTable;
duke@435	51	class GenRemSet;
duke@435	52	class CardTableRS;
duke@435	53	class DirtyCardToOopClosure;
duke@435	54
duke@435	55	// An oop closure that is circumscribed by a filtering memory region.
coleenp@548	56	class SpaceMemRegionOopsIterClosure: public OopClosure {
coleenp@548	57	private:
coleenp@548	58	OopClosure* _cl;
coleenp@548	59	MemRegion _mr;
coleenp@548	60	protected:
coleenp@548	61	template <class T> void do_oop_work(T* p) {
coleenp@548	62	if (_mr.contains(p)) {
coleenp@548	63	_cl->do_oop(p);
duke@435	64	}
duke@435	65	}
coleenp@548	66	public:
coleenp@548	67	SpaceMemRegionOopsIterClosure(OopClosure* cl, MemRegion mr):
coleenp@548	68	_cl(cl), _mr(mr) {}
coleenp@548	69	virtual void do_oop(oop* p);
coleenp@548	70	virtual void do_oop(narrowOop* p);
duke@435	71	};
duke@435	72
duke@435	73	// A Space describes a heap area. Class Space is an abstract
duke@435	74	// base class.
duke@435	75	//
duke@435	76	// Space supports allocation, size computation and GC support is provided.
duke@435	77	//
duke@435	78	// Invariant: bottom() and end() are on page_size boundaries and
duke@435	79	// bottom() <= top() <= end()
duke@435	80	// top() is inclusive and end() is exclusive.
duke@435	81
duke@435	82	class Space: public CHeapObj {
duke@435	83	friend class VMStructs;
duke@435	84	protected:
duke@435	85	HeapWord* _bottom;
duke@435	86	HeapWord* _end;
duke@435	87
duke@435	88	// Used in support of save_marks()
duke@435	89	HeapWord* _saved_mark_word;
duke@435	90
duke@435	91	MemRegionClosure* _preconsumptionDirtyCardClosure;
duke@435	92
duke@435	93	// A sequential tasks done structure. This supports
duke@435	94	// parallel GC, where we have threads dynamically
duke@435	95	// claiming sub-tasks from a larger parallel task.
duke@435	96	SequentialSubTasksDone _par_seq_tasks;
duke@435	97
duke@435	98	Space():
duke@435	99	_bottom(NULL), _end(NULL), _preconsumptionDirtyCardClosure(NULL) { }
duke@435	100
duke@435	101	public:
duke@435	102	// Accessors
duke@435	103	HeapWord* bottom() const { return _bottom; }
duke@435	104	HeapWord* end() const { return _end; }
duke@435	105	virtual void set_bottom(HeapWord* value) { _bottom = value; }
duke@435	106	virtual void set_end(HeapWord* value) { _end = value; }
duke@435	107
ysr@777	108	virtual HeapWord* saved_mark_word() const { return _saved_mark_word; }
duke@435	109	void set_saved_mark_word(HeapWord* p) { _saved_mark_word = p; }
duke@435	110
duke@435	111	MemRegionClosure* preconsumptionDirtyCardClosure() const {
duke@435	112	return _preconsumptionDirtyCardClosure;
duke@435	113	}
duke@435	114	void setPreconsumptionDirtyCardClosure(MemRegionClosure* cl) {
duke@435	115	_preconsumptionDirtyCardClosure = cl;
duke@435	116	}
duke@435	117
duke@435	118	// Returns a subregion of the space containing all the objects in
duke@435	119	// the space.
duke@435	120	virtual MemRegion used_region() const { return MemRegion(bottom(), end()); }
duke@435	121
duke@435	122	// Returns a region that is guaranteed to contain (at least) all objects
duke@435	123	// allocated at the time of the last call to "save_marks". If the space
duke@435	124	// initializes its DirtyCardToOopClosure's specifying the "contig" option
duke@435	125	// (that is, if the space is contiguous), then this region must contain only
duke@435	126	// such objects: the memregion will be from the bottom of the region to the
duke@435	127	// saved mark. Otherwise, the "obj_allocated_since_save_marks" method of
duke@435	128	// the space must distiguish between objects in the region allocated before
duke@435	129	// and after the call to save marks.
duke@435	130	virtual MemRegion used_region_at_save_marks() const {
duke@435	131	return MemRegion(bottom(), saved_mark_word());
duke@435	132	}
duke@435	133
ysr@777	134	// Initialization.
ysr@777	135	// "initialize" should be called once on a space, before it is used for
ysr@777	136	// any purpose. The "mr" arguments gives the bounds of the space, and
ysr@777	137	// the "clear_space" argument should be true unless the memory in "mr" is
ysr@777	138	// known to be zeroed.
duke@435	139	virtual void initialize(MemRegion mr, bool clear_space);
ysr@777	140
ysr@777	141	// Sets the bounds (bottom and end) of the current space to those of "mr."
ysr@777	142	void set_bounds(MemRegion mr);
ysr@777	143
ysr@777	144	// The "clear" method must be called on a region that may have
ysr@777	145	// had allocation performed in it, but is now to be considered empty.
duke@435	146	virtual void clear();
duke@435	147
duke@435	148	// For detecting GC bugs. Should only be called at GC boundaries, since
duke@435	149	// some unused space may be used as scratch space during GC's.
duke@435	150	// Default implementation does nothing. We also call this when expanding
duke@435	151	// a space to satisfy an allocation request. See bug #4668531
duke@435	152	virtual void mangle_unused_area() {}
duke@435	153	virtual void mangle_region(MemRegion mr) {}
duke@435	154
duke@435	155	// Testers
duke@435	156	bool is_empty() const { return used() == 0; }
duke@435	157	bool not_empty() const { return used() > 0; }
duke@435	158
duke@435	159	// Returns true iff the given the space contains the
duke@435	160	// given address as part of an allocated object. For
duke@435	161	// ceratin kinds of spaces, this might be a potentially
duke@435	162	// expensive operation. To prevent performance problems
duke@435	163	// on account of its inadvertent use in product jvm's,
duke@435	164	// we restrict its use to assertion checks only.
duke@435	165	virtual bool is_in(const void* p) const;
duke@435	166
duke@435	167	// Returns true iff the given reserved memory of the space contains the
duke@435	168	// given address.
duke@435	169	bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; }
duke@435	170
duke@435	171	// Returns true iff the given block is not allocated.
duke@435	172	virtual bool is_free_block(const HeapWord* p) const = 0;
duke@435	173
duke@435	174	// Test whether p is double-aligned
duke@435	175	static bool is_aligned(void* p) {
duke@435	176	return ((intptr_t)p & (sizeof(double)-1)) == 0;
duke@435	177	}
duke@435	178
duke@435	179	// Size computations. Sizes are in bytes.
duke@435	180	size_t capacity() const { return byte_size(bottom(), end()); }
duke@435	181	virtual size_t used() const = 0;
duke@435	182	virtual size_t free() const = 0;
duke@435	183
duke@435	184	// Iterate over all the ref-containing fields of all objects in the
duke@435	185	// space, calling "cl.do_oop" on each. Fields in objects allocated by
duke@435	186	// applications of the closure are not included in the iteration.
duke@435	187	virtual void oop_iterate(OopClosure* cl);
duke@435	188
duke@435	189	// Same as above, restricted to the intersection of a memory region and
duke@435	190	// the space. Fields in objects allocated by applications of the closure
duke@435	191	// are not included in the iteration.
duke@435	192	virtual void oop_iterate(MemRegion mr, OopClosure* cl) = 0;
duke@435	193
duke@435	194	// Iterate over all objects in the space, calling "cl.do_object" on
duke@435	195	// each. Objects allocated by applications of the closure are not
duke@435	196	// included in the iteration.
duke@435	197	virtual void object_iterate(ObjectClosure* blk) = 0;
duke@435	198
duke@435	199	// Iterate over all objects that intersect with mr, calling "cl->do_object"
duke@435	200	// on each. There is an exception to this: if this closure has already
duke@435	201	// been invoked on an object, it may skip such objects in some cases. This is
duke@435	202	// Most likely to happen in an "upwards" (ascending address) iteration of
duke@435	203	// MemRegions.
duke@435	204	virtual void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);
duke@435	205
duke@435	206	// Iterate over as many initialized objects in the space as possible,
duke@435	207	// calling "cl.do_object_careful" on each. Return NULL if all objects
duke@435	208	// in the space (at the start of the iteration) were iterated over.
duke@435	209	// Return an address indicating the extent of the iteration in the
duke@435	210	// event that the iteration had to return because of finding an
duke@435	211	// uninitialized object in the space, or if the closure "cl"
duke@435	212	// signalled early termination.
duke@435	213	virtual HeapWord* object_iterate_careful(ObjectClosureCareful* cl);
duke@435	214	virtual HeapWord* object_iterate_careful_m(MemRegion mr,
duke@435	215	ObjectClosureCareful* cl);
duke@435	216
duke@435	217	// Create and return a new dirty card to oop closure. Can be
duke@435	218	// overriden to return the appropriate type of closure
duke@435	219	// depending on the type of space in which the closure will
duke@435	220	// operate. ResourceArea allocated.
duke@435	221	virtual DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl,
duke@435	222	CardTableModRefBS::PrecisionStyle precision,
duke@435	223	HeapWord* boundary = NULL);
duke@435	224
duke@435	225	// If "p" is in the space, returns the address of the start of the
duke@435	226	// "block" that contains "p". We say "block" instead of "object" since
duke@435	227	// some heaps may not pack objects densely; a chunk may either be an
duke@435	228	// object or a non-object. If "p" is not in the space, return NULL.
ysr@777	229	virtual HeapWord* block_start_const(const void* p) const = 0;
ysr@777	230
ysr@777	231	// The non-const version may have benevolent side effects on the data
ysr@777	232	// structure supporting these calls, possibly speeding up future calls.
ysr@777	233	// The default implementation, however, is simply to call the const
ysr@777	234	// version.
ysr@777	235	inline virtual HeapWord* block_start(const void* p);
duke@435	236
duke@435	237	// Requires "addr" to be the start of a chunk, and returns its size.
duke@435	238	// "addr + size" is required to be the start of a new chunk, or the end
duke@435	239	// of the active area of the heap.
duke@435	240	virtual size_t block_size(const HeapWord* addr) const = 0;
duke@435	241
duke@435	242	// Requires "addr" to be the start of a block, and returns "TRUE" iff
duke@435	243	// the block is an object.
duke@435	244	virtual bool block_is_obj(const HeapWord* addr) const = 0;
duke@435	245
duke@435	246	// Requires "addr" to be the start of a block, and returns "TRUE" iff
duke@435	247	// the block is an object and the object is alive.
duke@435	248	virtual bool obj_is_alive(const HeapWord* addr) const;
duke@435	249
duke@435	250	// Allocation (return NULL if full). Assumes the caller has established
duke@435	251	// mutually exclusive access to the space.
duke@435	252	virtual HeapWord* allocate(size_t word_size) = 0;
duke@435	253
duke@435	254	// Allocation (return NULL if full). Enforces mutual exclusion internally.
duke@435	255	virtual HeapWord* par_allocate(size_t word_size) = 0;
duke@435	256
duke@435	257	// Returns true if this object has been allocated since a
duke@435	258	// generation's "save_marks" call.
duke@435	259	virtual bool obj_allocated_since_save_marks(const oop obj) const = 0;
duke@435	260
duke@435	261	// Mark-sweep-compact support: all spaces can update pointers to objects
duke@435	262	// moving as a part of compaction.
duke@435	263	virtual void adjust_pointers();
duke@435	264
duke@435	265	// PrintHeapAtGC support
duke@435	266	virtual void print() const;
duke@435	267	virtual void print_on(outputStream* st) const;
duke@435	268	virtual void print_short() const;
duke@435	269	virtual void print_short_on(outputStream* st) const;
duke@435	270
duke@435	271
duke@435	272	// Accessor for parallel sequential tasks.
duke@435	273	SequentialSubTasksDone* par_seq_tasks() { return &_par_seq_tasks; }
duke@435	274
duke@435	275	// IF "this" is a ContiguousSpace, return it, else return NULL.
duke@435	276	virtual ContiguousSpace* toContiguousSpace() {
duke@435	277	return NULL;
duke@435	278	}
duke@435	279
duke@435	280	// Debugging
duke@435	281	virtual void verify(bool allow_dirty) const = 0;
duke@435	282	};
duke@435	283
duke@435	284	// A MemRegionClosure (ResourceObj) whose "do_MemRegion" function applies an
duke@435	285	// OopClosure to (the addresses of) all the ref-containing fields that could
duke@435	286	// be modified by virtue of the given MemRegion being dirty. (Note that
duke@435	287	// because of the imprecise nature of the write barrier, this may iterate
duke@435	288	// over oops beyond the region.)
duke@435	289	// This base type for dirty card to oop closures handles memory regions
duke@435	290	// in non-contiguous spaces with no boundaries, and should be sub-classed
duke@435	291	// to support other space types. See ContiguousDCTOC for a sub-class
duke@435	292	// that works with ContiguousSpaces.
duke@435	293
duke@435	294	class DirtyCardToOopClosure: public MemRegionClosureRO {
duke@435	295	protected:
duke@435	296	OopClosure* _cl;
duke@435	297	Space* _sp;
duke@435	298	CardTableModRefBS::PrecisionStyle _precision;
duke@435	299	HeapWord* _boundary; // If non-NULL, process only non-NULL oops
duke@435	300	// pointing below boundary.
ysr@777	301	HeapWord* _min_done; // ObjHeadPreciseArray precision requires
duke@435	302	// a downwards traversal; this is the
duke@435	303	// lowest location already done (or,
duke@435	304	// alternatively, the lowest address that
duke@435	305	// shouldn't be done again. NULL means infinity.)
duke@435	306	NOT_PRODUCT(HeapWord* _last_bottom;)
ysr@777	307	NOT_PRODUCT(HeapWord* _last_explicit_min_done;)
duke@435	308
duke@435	309	// Get the actual top of the area on which the closure will
duke@435	310	// operate, given where the top is assumed to be (the end of the
duke@435	311	// memory region passed to do_MemRegion) and where the object
duke@435	312	// at the top is assumed to start. For example, an object may
duke@435	313	// start at the top but actually extend past the assumed top,
duke@435	314	// in which case the top becomes the end of the object.
duke@435	315	virtual HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);
duke@435	316
duke@435	317	// Walk the given memory region from bottom to (actual) top
duke@435	318	// looking for objects and applying the oop closure (_cl) to
duke@435	319	// them. The base implementation of this treats the area as
duke@435	320	// blocks, where a block may or may not be an object. Sub-
duke@435	321	// classes should override this to provide more accurate
duke@435	322	// or possibly more efficient walking.
duke@435	323	virtual void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
duke@435	324
duke@435	325	public:
duke@435	326	DirtyCardToOopClosure(Space* sp, OopClosure* cl,
duke@435	327	CardTableModRefBS::PrecisionStyle precision,
duke@435	328	HeapWord* boundary) :
duke@435	329	_sp(sp), _cl(cl), _precision(precision), _boundary(boundary),
duke@435	330	_min_done(NULL) {
ysr@777	331	NOT_PRODUCT(_last_bottom = NULL);
ysr@777	332	NOT_PRODUCT(_last_explicit_min_done = NULL);
duke@435	333	}
duke@435	334
duke@435	335	void do_MemRegion(MemRegion mr);
duke@435	336
duke@435	337	void set_min_done(HeapWord* min_done) {
duke@435	338	_min_done = min_done;
ysr@777	339	NOT_PRODUCT(_last_explicit_min_done = _min_done);
duke@435	340	}
duke@435	341	#ifndef PRODUCT
duke@435	342	void set_last_bottom(HeapWord* last_bottom) {
duke@435	343	_last_bottom = last_bottom;
duke@435	344	}
duke@435	345	#endif
duke@435	346	};
duke@435	347
duke@435	348	// A structure to represent a point at which objects are being copied
duke@435	349	// during compaction.
duke@435	350	class CompactPoint : public StackObj {
duke@435	351	public:
duke@435	352	Generation* gen;
duke@435	353	CompactibleSpace* space;
duke@435	354	HeapWord* threshold;
duke@435	355	CompactPoint(Generation* _gen, CompactibleSpace* _space,
duke@435	356	HeapWord* _threshold) :
duke@435	357	gen(_gen), space(_space), threshold(_threshold) {}
duke@435	358	};
duke@435	359
duke@435	360
duke@435	361	// A space that supports compaction operations. This is usually, but not
duke@435	362	// necessarily, a space that is normally contiguous. But, for example, a
duke@435	363	// free-list-based space whose normal collection is a mark-sweep without
duke@435	364	// compaction could still support compaction in full GC's.
duke@435	365
duke@435	366	class CompactibleSpace: public Space {
duke@435	367	friend class VMStructs;
duke@435	368	friend class CompactibleFreeListSpace;
duke@435	369	friend class CompactingPermGenGen;
duke@435	370	friend class CMSPermGenGen;
duke@435	371	private:
duke@435	372	HeapWord* _compaction_top;
duke@435	373	CompactibleSpace* _next_compaction_space;
duke@435	374
duke@435	375	public:
duke@435	376	virtual void initialize(MemRegion mr, bool clear_space);
ysr@777	377	virtual void clear();
duke@435	378
duke@435	379	// Used temporarily during a compaction phase to hold the value
duke@435	380	// top should have when compaction is complete.
duke@435	381	HeapWord* compaction_top() const { return _compaction_top; }
duke@435	382
duke@435	383	void set_compaction_top(HeapWord* value) {
duke@435	384	assert(value == NULL || (value >= bottom() && value <= end()),
duke@435	385	"should point inside space");
duke@435	386	_compaction_top = value;
duke@435	387	}
duke@435	388
duke@435	389	// Perform operations on the space needed after a compaction
duke@435	390	// has been performed.
duke@435	391	virtual void reset_after_compaction() {}
duke@435	392
duke@435	393	// Returns the next space (in the current generation) to be compacted in
duke@435	394	// the global compaction order. Also is used to select the next
duke@435	395	// space into which to compact.
duke@435	396
duke@435	397	virtual CompactibleSpace* next_compaction_space() const {
duke@435	398	return _next_compaction_space;
duke@435	399	}
duke@435	400
duke@435	401	void set_next_compaction_space(CompactibleSpace* csp) {
duke@435	402	_next_compaction_space = csp;
duke@435	403	}
duke@435	404
duke@435	405	// MarkSweep support phase2
duke@435	406
duke@435	407	// Start the process of compaction of the current space: compute
duke@435	408	// post-compaction addresses, and insert forwarding pointers. The fields
duke@435	409	// "cp->gen" and "cp->compaction_space" are the generation and space into
duke@435	410	// which we are currently compacting. This call updates "cp" as necessary,
duke@435	411	// and leaves the "compaction_top" of the final value of
duke@435	412	// "cp->compaction_space" up-to-date. Offset tables may be updated in
duke@435	413	// this phase as if the final copy had occurred; if so, "cp->threshold"
duke@435	414	// indicates when the next such action should be taken.
duke@435	415	virtual void prepare_for_compaction(CompactPoint* cp);
duke@435	416	// MarkSweep support phase3
duke@435	417	virtual void adjust_pointers();
duke@435	418	// MarkSweep support phase4
duke@435	419	virtual void compact();
duke@435	420
duke@435	421	// The maximum percentage of objects that can be dead in the compacted
duke@435	422	// live part of a compacted space ("deadwood" support.)
duke@435	423	virtual int allowed_dead_ratio() const { return 0; };
duke@435	424
duke@435	425	// Some contiguous spaces may maintain some data structures that should
duke@435	426	// be updated whenever an allocation crosses a boundary. This function
duke@435	427	// returns the first such boundary.
duke@435	428	// (The default implementation returns the end of the space, so the
duke@435	429	// boundary is never crossed.)
duke@435	430	virtual HeapWord* initialize_threshold() { return end(); }
duke@435	431
duke@435	432	// "q" is an object of the given "size" that should be forwarded;
duke@435	433	// "cp" names the generation ("gen") and containing "this" (which must
duke@435	434	// also equal "cp->space"). "compact_top" is where in "this" the
duke@435	435	// next object should be forwarded to. If there is room in "this" for
duke@435	436	// the object, insert an appropriate forwarding pointer in "q".
duke@435	437	// If not, go to the next compaction space (there must
duke@435	438	// be one, since compaction must succeed -- we go to the first space of
duke@435	439	// the previous generation if necessary, updating "cp"), reset compact_top
duke@435	440	// and then forward. In either case, returns the new value of "compact_top".
duke@435	441	// If the forwarding crosses "cp->threshold", invokes the "cross_threhold"
duke@435	442	// function of the then-current compaction space, and updates "cp->threshold
duke@435	443	// accordingly".
duke@435	444	virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp,
duke@435	445	HeapWord* compact_top);
duke@435	446
duke@435	447	// Return a size with adjusments as required of the space.
duke@435	448	virtual size_t adjust_object_size_v(size_t size) const { return size; }
duke@435	449
duke@435	450	protected:
duke@435	451	// Used during compaction.
duke@435	452	HeapWord* _first_dead;
duke@435	453	HeapWord* _end_of_live;
duke@435	454
duke@435	455	// Minimum size of a free block.
duke@435	456	virtual size_t minimum_free_block_size() const = 0;
duke@435	457
duke@435	458	// This the function is invoked when an allocation of an object covering
duke@435	459	// "start" to "end occurs crosses the threshold; returns the next
duke@435	460	// threshold. (The default implementation does nothing.)
duke@435	461	virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* the_end) {
duke@435	462	return end();
duke@435	463	}
duke@435	464
duke@435	465	// Requires "allowed_deadspace_words > 0", that "q" is the start of a
duke@435	466	// free block of the given "word_len", and that "q", were it an object,
duke@435	467	// would not move if forwared. If the size allows, fill the free
duke@435	468	// block with an object, to prevent excessive compaction. Returns "true"
duke@435	469	// iff the free region was made deadspace, and modifies
duke@435	470	// "allowed_deadspace_words" to reflect the number of available deadspace
duke@435	471	// words remaining after this operation.
duke@435	472	bool insert_deadspace(size_t& allowed_deadspace_words, HeapWord* q,
duke@435	473	size_t word_len);
duke@435	474	};
duke@435	475
duke@435	476	#define SCAN_AND_FORWARD(cp,scan_limit,block_is_obj,block_size) { \
duke@435	477	/* Compute the new addresses for the live objects and store it in the mark \
duke@435	478	* Used by universe::mark_sweep_phase2() \
duke@435	479	*/ \
duke@435	480	HeapWord* compact_top; /* This is where we are currently compacting to. */ \
duke@435	481	\
duke@435	482	/* We're sure to be here before any objects are compacted into this \
duke@435	483	* space, so this is a good time to initialize this: \
duke@435	484	*/ \
duke@435	485	set_compaction_top(bottom()); \
duke@435	486	\
duke@435	487	if (cp->space == NULL) { \
duke@435	488	assert(cp->gen != NULL, "need a generation"); \
duke@435	489	assert(cp->threshold == NULL, "just checking"); \
duke@435	490	assert(cp->gen->first_compaction_space() == this, "just checking"); \
duke@435	491	cp->space = cp->gen->first_compaction_space(); \
duke@435	492	compact_top = cp->space->bottom(); \
duke@435	493	cp->space->set_compaction_top(compact_top); \
duke@435	494	cp->threshold = cp->space->initialize_threshold(); \
duke@435	495	} else { \
duke@435	496	compact_top = cp->space->compaction_top(); \
duke@435	497	} \
duke@435	498	\
duke@435	499	/* We allow some amount of garbage towards the bottom of the space, so \
duke@435	500	* we don't start compacting before there is a significant gain to be made.\
duke@435	501	* Occasionally, we want to ensure a full compaction, which is determined \
duke@435	502	* by the MarkSweepAlwaysCompactCount parameter. \
duke@435	503	*/ \
duke@435	504	int invocations = SharedHeap::heap()->perm_gen()->stat_record()->invocations;\
duke@435	505	bool skip_dead = ((invocations % MarkSweepAlwaysCompactCount) != 0); \
duke@435	506	\
duke@435	507	size_t allowed_deadspace = 0; \
duke@435	508	if (skip_dead) { \
duke@435	509	int ratio = allowed_dead_ratio(); \
duke@435	510	allowed_deadspace = (capacity() * ratio / 100) / HeapWordSize; \
duke@435	511	} \
duke@435	512	\
duke@435	513	HeapWord* q = bottom(); \
duke@435	514	HeapWord* t = scan_limit(); \
duke@435	515	\
duke@435	516	HeapWord* end_of_live= q; /* One byte beyond the last byte of the last \
duke@435	517	live object. */ \
duke@435	518	HeapWord* first_dead = end();/* The first dead object. */ \
duke@435	519	LiveRange* liveRange = NULL; /* The current live range, recorded in the \
duke@435	520	first header of preceding free area. */ \
duke@435	521	_first_dead = first_dead; \
duke@435	522	\
duke@435	523	const intx interval = PrefetchScanIntervalInBytes; \
duke@435	524	\
duke@435	525	while (q < t) { \
duke@435	526	assert(!block_is_obj(q) || \
duke@435	527	oop(q)->mark()->is_marked() || oop(q)->mark()->is_unlocked() || \
duke@435	528	oop(q)->mark()->has_bias_pattern(), \
duke@435	529	"these are the only valid states during a mark sweep"); \
duke@435	530	if (block_is_obj(q) && oop(q)->is_gc_marked()) { \
duke@435	531	/* prefetch beyond q */ \
duke@435	532	Prefetch::write(q, interval); \
duke@435	533	/* size_t size = oop(q)->size(); changing this for cms for perm gen */\
ysr@777	534	size_t size = block_size(q); \
duke@435	535	compact_top = cp->space->forward(oop(q), size, cp, compact_top); \
duke@435	536	q += size; \
duke@435	537	end_of_live = q; \
duke@435	538	} else { \
duke@435	539	/* run over all the contiguous dead objects */ \
duke@435	540	HeapWord* end = q; \
duke@435	541	do { \
duke@435	542	/* prefetch beyond end */ \
duke@435	543	Prefetch::write(end, interval); \
duke@435	544	end += block_size(end); \
duke@435	545	} while (end < t && (!block_is_obj(end) || !oop(end)->is_gc_marked()));\
duke@435	546	\
duke@435	547	/* see if we might want to pretend this object is alive so that \
duke@435	548	* we don't have to compact quite as often. \
duke@435	549	*/ \
duke@435	550	if (allowed_deadspace > 0 && q == compact_top) { \
duke@435	551	size_t sz = pointer_delta(end, q); \
duke@435	552	if (insert_deadspace(allowed_deadspace, q, sz)) { \
duke@435	553	compact_top = cp->space->forward(oop(q), sz, cp, compact_top); \
duke@435	554	q = end; \
duke@435	555	end_of_live = end; \
duke@435	556	continue; \
duke@435	557	} \
duke@435	558	} \
duke@435	559	\
duke@435	560	/* otherwise, it really is a free region. */ \
duke@435	561	\
duke@435	562	/* for the previous LiveRange, record the end of the live objects. */ \
duke@435	563	if (liveRange) { \
duke@435	564	liveRange->set_end(q); \
duke@435	565	} \
duke@435	566	\
duke@435	567	/* record the current LiveRange object. \
duke@435	568	* liveRange->start() is overlaid on the mark word. \
duke@435	569	*/ \
duke@435	570	liveRange = (LiveRange*)q; \
duke@435	571	liveRange->set_start(end); \
duke@435	572	liveRange->set_end(end); \
duke@435	573	\
duke@435	574	/* see if this is the first dead region. */ \
duke@435	575	if (q < first_dead) { \
duke@435	576	first_dead = q; \
duke@435	577	} \
duke@435	578	\
duke@435	579	/* move on to the next object */ \
duke@435	580	q = end; \
duke@435	581	} \
duke@435	582	} \
duke@435	583	\
duke@435	584	assert(q == t, "just checking"); \
duke@435	585	if (liveRange != NULL) { \
duke@435	586	liveRange->set_end(q); \
duke@435	587	} \
duke@435	588	_end_of_live = end_of_live; \
duke@435	589	if (end_of_live < first_dead) { \
duke@435	590	first_dead = end_of_live; \
duke@435	591	} \
duke@435	592	_first_dead = first_dead; \
duke@435	593	\
duke@435	594	/* save the compaction_top of the compaction space. */ \
duke@435	595	cp->space->set_compaction_top(compact_top); \
duke@435	596	}
duke@435	597
ysr@777	598	#define SCAN_AND_ADJUST_POINTERS(adjust_obj_size) { \
ysr@777	599	/* adjust all the interior pointers to point at the new locations of objects \
ysr@777	600	* Used by MarkSweep::mark_sweep_phase3() */ \
duke@435	601	\
ysr@777	602	HeapWord* q = bottom(); \
ysr@777	603	HeapWord* t = _end_of_live; /* Established by "prepare_for_compaction". */ \
duke@435	604	\
ysr@777	605	assert(_first_dead <= _end_of_live, "Stands to reason, no?"); \
duke@435	606	\
ysr@777	607	if (q < t && _first_dead > q && \
duke@435	608	!oop(q)->is_gc_marked()) { \
duke@435	609	/* we have a chunk of the space which hasn't moved and we've \
duke@435	610	* reinitialized the mark word during the previous pass, so we can't \
ysr@777	611	* use is_gc_marked for the traversal. */ \
duke@435	612	HeapWord* end = _first_dead; \
duke@435	613	\
ysr@777	614	while (q < end) { \
ysr@777	615	/* I originally tried to conjoin "block_start(q) == q" to the \
ysr@777	616	* assertion below, but that doesn't work, because you can't \
ysr@777	617	* accurately traverse previous objects to get to the current one \
ysr@777	618	* after their pointers (including pointers into permGen) have been \
ysr@777	619	* updated, until the actual compaction is done. dld, 4/00 */ \
ysr@777	620	assert(block_is_obj(q), \
ysr@777	621	"should be at block boundaries, and should be looking at objs"); \
duke@435	622	\
coleenp@548	623	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q))); \
duke@435	624	\
ysr@777	625	/* point all the oops to the new location */ \
ysr@777	626	size_t size = oop(q)->adjust_pointers(); \
ysr@777	627	size = adjust_obj_size(size); \
duke@435	628	\
coleenp@548	629	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers()); \
ysr@777	630	\
coleenp@548	631	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size)); \
ysr@777	632	\
coleenp@548	633	q += size; \
ysr@777	634	} \
duke@435	635	\
ysr@777	636	if (_first_dead == t) { \
ysr@777	637	q = t; \
ysr@777	638	} else { \
ysr@777	639	/* $$$ This is funky. Using this to read the previously written \
ysr@777	640	* LiveRange. See also use below. */ \
duke@435	641	q = (HeapWord*)oop(_first_dead)->mark()->decode_pointer(); \
ysr@777	642	} \
ysr@777	643	} \
duke@435	644	\
duke@435	645	const intx interval = PrefetchScanIntervalInBytes; \
duke@435	646	\
ysr@777	647	debug_only(HeapWord* prev_q = NULL); \
ysr@777	648	while (q < t) { \
ysr@777	649	/* prefetch beyond q */ \
duke@435	650	Prefetch::write(q, interval); \
ysr@777	651	if (oop(q)->is_gc_marked()) { \
ysr@777	652	/* q is alive */ \
coleenp@548	653	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q))); \
ysr@777	654	/* point all the oops to the new location */ \
ysr@777	655	size_t size = oop(q)->adjust_pointers(); \
ysr@777	656	size = adjust_obj_size(size); \
ysr@777	657	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers()); \
coleenp@548	658	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size)); \
ysr@777	659	debug_only(prev_q = q); \
duke@435	660	q += size; \
coleenp@548	661	} else { \
coleenp@548	662	/* q is not a live object, so its mark should point at the next \
coleenp@548	663	* live object */ \
coleenp@548	664	debug_only(prev_q = q); \
coleenp@548	665	q = (HeapWord*) oop(q)->mark()->decode_pointer(); \
coleenp@548	666	assert(q > prev_q, "we should be moving forward through memory"); \
coleenp@548	667	} \
coleenp@548	668	} \
duke@435	669	\
coleenp@548	670	assert(q == t, "just checking"); \
duke@435	671	}
duke@435	672
coleenp@548	673	#define SCAN_AND_COMPACT(obj_size) { \
duke@435	674	/* Copy all live objects to their new location \
coleenp@548	675	* Used by MarkSweep::mark_sweep_phase4() */ \
duke@435	676	\
coleenp@548	677	HeapWord* q = bottom(); \
coleenp@548	678	HeapWord* const t = _end_of_live; \
coleenp@548	679	debug_only(HeapWord* prev_q = NULL); \
duke@435	680	\
coleenp@548	681	if (q < t && _first_dead > q && \
duke@435	682	!oop(q)->is_gc_marked()) { \
coleenp@548	683	debug_only( \
coleenp@548	684	/* we have a chunk of the space which hasn't moved and we've reinitialized \
coleenp@548	685	* the mark word during the previous pass, so we can't use is_gc_marked for \
coleenp@548	686	* the traversal. */ \
coleenp@548	687	HeapWord* const end = _first_dead; \
coleenp@548	688	\
coleenp@548	689	while (q < end) { \
coleenp@548	690	size_t size = obj_size(q); \
coleenp@548	691	assert(!oop(q)->is_gc_marked(), \
coleenp@548	692	"should be unmarked (special dense prefix handling)"); \
coleenp@548	693	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size, q)); \
coleenp@548	694	debug_only(prev_q = q); \
coleenp@548	695	q += size; \
coleenp@548	696	} \
coleenp@548	697	) /* debug_only */ \
coleenp@548	698	\
coleenp@548	699	if (_first_dead == t) { \
coleenp@548	700	q = t; \
coleenp@548	701	} else { \
coleenp@548	702	/* $$$ Funky */ \
coleenp@548	703	q = (HeapWord*) oop(_first_dead)->mark()->decode_pointer(); \
coleenp@548	704	} \
coleenp@548	705	} \
duke@435	706	\
coleenp@548	707	const intx scan_interval = PrefetchScanIntervalInBytes; \
coleenp@548	708	const intx copy_interval = PrefetchCopyIntervalInBytes; \
coleenp@548	709	while (q < t) { \
coleenp@548	710	if (!oop(q)->is_gc_marked()) { \
coleenp@548	711	/* mark is pointer to next marked oop */ \
coleenp@548	712	debug_only(prev_q = q); \
coleenp@548	713	q = (HeapWord*) oop(q)->mark()->decode_pointer(); \
coleenp@548	714	assert(q > prev_q, "we should be moving forward through memory"); \
coleenp@548	715	} else { \
coleenp@548	716	/* prefetch beyond q */ \
duke@435	717	Prefetch::read(q, scan_interval); \
duke@435	718	\
duke@435	719	/* size and destination */ \
duke@435	720	size_t size = obj_size(q); \
duke@435	721	HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee(); \
duke@435	722	\
coleenp@548	723	/* prefetch beyond compaction_top */ \
duke@435	724	Prefetch::write(compaction_top, copy_interval); \
duke@435	725	\
coleenp@548	726	/* copy object and reinit its mark */ \
coleenp@548	727	VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size, \
coleenp@548	728	compaction_top)); \
coleenp@548	729	assert(q != compaction_top, "everything in this pass should be moving"); \
coleenp@548	730	Copy::aligned_conjoint_words(q, compaction_top, size); \
coleenp@548	731	oop(compaction_top)->init_mark(); \
coleenp@548	732	assert(oop(compaction_top)->klass() != NULL, "should have a class"); \
duke@435	733	\
coleenp@548	734	debug_only(prev_q = q); \
duke@435	735	q += size; \
coleenp@548	736	} \
coleenp@548	737	} \
duke@435	738	\
ysr@777	739	/* Let's remember if we were empty before we did the compaction. */ \
ysr@777	740	bool was_empty = used_region().is_empty(); \
duke@435	741	/* Reset space after compaction is complete */ \
coleenp@548	742	reset_after_compaction(); \
duke@435	743	/* We do this clear, below, since it has overloaded meanings for some */ \
duke@435	744	/* space subtypes. For example, OffsetTableContigSpace's that were */ \
duke@435	745	/* compacted into will have had their offset table thresholds updated */ \
duke@435	746	/* continuously, but those that weren't need to have their thresholds */ \
duke@435	747	/* re-initialized. Also mangles unused area for debugging. */ \
ysr@777	748	if (used_region().is_empty()) { \
ysr@777	749	if (!was_empty) clear(); \
duke@435	750	} else { \
duke@435	751	if (ZapUnusedHeapArea) mangle_unused_area(); \
duke@435	752	} \
duke@435	753	}
duke@435	754
duke@435	755	// A space in which the free area is contiguous. It therefore supports
duke@435	756	// faster allocation, and compaction.
duke@435	757	class ContiguousSpace: public CompactibleSpace {
duke@435	758	friend class OneContigSpaceCardGeneration;
duke@435	759	friend class VMStructs;
duke@435	760	protected:
duke@435	761	HeapWord* _top;
duke@435	762	HeapWord* _concurrent_iteration_safe_limit;
duke@435	763
duke@435	764	// Allocation helpers (return NULL if full).
duke@435	765	inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
duke@435	766	inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
duke@435	767
duke@435	768	public:
duke@435	769	virtual void initialize(MemRegion mr, bool clear_space);
duke@435	770
duke@435	771	// Accessors
duke@435	772	HeapWord* top() const { return _top; }
duke@435	773	void set_top(HeapWord* value) { _top = value; }
duke@435	774
ysr@777	775	virtual void set_saved_mark() { _saved_mark_word = top(); }
ysr@777	776	void reset_saved_mark() { _saved_mark_word = bottom(); }
duke@435	777
duke@435	778	virtual void clear();
duke@435	779
duke@435	780	WaterMark bottom_mark() { return WaterMark(this, bottom()); }
duke@435	781	WaterMark top_mark() { return WaterMark(this, top()); }
duke@435	782	WaterMark saved_mark() { return WaterMark(this, saved_mark_word()); }
duke@435	783	bool saved_mark_at_top() const { return saved_mark_word() == top(); }
duke@435	784
duke@435	785	void mangle_unused_area();
duke@435	786	void mangle_region(MemRegion mr);
duke@435	787
duke@435	788	// Size computations: sizes in bytes.
duke@435	789	size_t capacity() const { return byte_size(bottom(), end()); }
duke@435	790	size_t used() const { return byte_size(bottom(), top()); }
duke@435	791	size_t free() const { return byte_size(top(), end()); }
duke@435	792
duke@435	793	// Override from space.
duke@435	794	bool is_in(const void* p) const;
duke@435	795
duke@435	796	virtual bool is_free_block(const HeapWord* p) const;
duke@435	797
duke@435	798	// In a contiguous space we have a more obvious bound on what parts
duke@435	799	// contain objects.
duke@435	800	MemRegion used_region() const { return MemRegion(bottom(), top()); }
duke@435	801
duke@435	802	MemRegion used_region_at_save_marks() const {
duke@435	803	return MemRegion(bottom(), saved_mark_word());
duke@435	804	}
duke@435	805
duke@435	806	// Allocation (return NULL if full)
duke@435	807	virtual HeapWord* allocate(size_t word_size);
duke@435	808	virtual HeapWord* par_allocate(size_t word_size);
duke@435	809
duke@435	810	virtual bool obj_allocated_since_save_marks(const oop obj) const {
duke@435	811	return (HeapWord*)obj >= saved_mark_word();
duke@435	812	}
duke@435	813
duke@435	814	// Iteration
duke@435	815	void oop_iterate(OopClosure* cl);
duke@435	816	void oop_iterate(MemRegion mr, OopClosure* cl);
duke@435	817	void object_iterate(ObjectClosure* blk);
duke@435	818	void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);
duke@435	819	// iterates on objects up to the safe limit
duke@435	820	HeapWord* object_iterate_careful(ObjectClosureCareful* cl);
duke@435	821	inline HeapWord* concurrent_iteration_safe_limit();
duke@435	822	// changes the safe limit, all objects from bottom() to the new
duke@435	823	// limit should be properly initialized
duke@435	824	inline void set_concurrent_iteration_safe_limit(HeapWord* new_limit);
duke@435	825
duke@435	826	#ifndef SERIALGC
duke@435	827	// In support of parallel oop_iterate.
duke@435	828	#define ContigSpace_PAR_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
duke@435	829	void par_oop_iterate(MemRegion mr, OopClosureType* blk);
duke@435	830
duke@435	831	ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DECL)
duke@435	832	#undef ContigSpace_PAR_OOP_ITERATE_DECL
duke@435	833	#endif // SERIALGC
duke@435	834
duke@435	835	// Compaction support
duke@435	836	virtual void reset_after_compaction() {
duke@435	837	assert(compaction_top() >= bottom() && compaction_top() <= end(), "should point inside space");
duke@435	838	set_top(compaction_top());
duke@435	839	// set new iteration safe limit
duke@435	840	set_concurrent_iteration_safe_limit(compaction_top());
duke@435	841	}
duke@435	842	virtual size_t minimum_free_block_size() const { return 0; }
duke@435	843
duke@435	844	// Override.
duke@435	845	DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl,
duke@435	846	CardTableModRefBS::PrecisionStyle precision,
duke@435	847	HeapWord* boundary = NULL);
duke@435	848
duke@435	849	// Apply "blk->do_oop" to the addresses of all reference fields in objects
duke@435	850	// starting with the _saved_mark_word, which was noted during a generation's
duke@435	851	// save_marks and is required to denote the head of an object.
duke@435	852	// Fields in objects allocated by applications of the closure
duke@435	853	// *are* included in the iteration.
duke@435	854	// Updates _saved_mark_word to point to just after the last object
duke@435	855	// iterated over.
duke@435	856	#define ContigSpace_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
duke@435	857	void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk);
duke@435	858
duke@435	859	ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DECL)
duke@435	860	#undef ContigSpace_OOP_SINCE_SAVE_MARKS_DECL
duke@435	861
duke@435	862	// Same as object_iterate, but starting from "mark", which is required
duke@435	863	// to denote the start of an object. Objects allocated by
duke@435	864	// applications of the closure *are* included in the iteration.
duke@435	865	virtual void object_iterate_from(WaterMark mark, ObjectClosure* blk);
duke@435	866
duke@435	867	// Very inefficient implementation.
ysr@777	868	virtual HeapWord* block_start_const(const void* p) const;
duke@435	869	size_t block_size(const HeapWord* p) const;
duke@435	870	// If a block is in the allocated area, it is an object.
duke@435	871	bool block_is_obj(const HeapWord* p) const { return p < top(); }
duke@435	872
duke@435	873	// Addresses for inlined allocation
duke@435	874	HeapWord** top_addr() { return &_top; }
duke@435	875	HeapWord** end_addr() { return &_end; }
duke@435	876
duke@435	877	// Overrides for more efficient compaction support.
duke@435	878	void prepare_for_compaction(CompactPoint* cp);
duke@435	879
duke@435	880	// PrintHeapAtGC support.
duke@435	881	virtual void print_on(outputStream* st) const;
duke@435	882
duke@435	883	// Checked dynamic downcasts.
duke@435	884	virtual ContiguousSpace* toContiguousSpace() {
duke@435	885	return this;
duke@435	886	}
duke@435	887
duke@435	888	// Debugging
duke@435	889	virtual void verify(bool allow_dirty) const;
duke@435	890
duke@435	891	// Used to increase collection frequency. "factor" of 0 means entire
duke@435	892	// space.
duke@435	893	void allocate_temporary_filler(int factor);
duke@435	894
duke@435	895	};
duke@435	896
duke@435	897
duke@435	898	// A dirty card to oop closure that does filtering.
duke@435	899	// It knows how to filter out objects that are outside of the _boundary.
duke@435	900	class Filtering_DCTOC : public DirtyCardToOopClosure {
duke@435	901	protected:
duke@435	902	// Override.
duke@435	903	void walk_mem_region(MemRegion mr,
duke@435	904	HeapWord* bottom, HeapWord* top);
duke@435	905
duke@435	906	// Walk the given memory region, from bottom to top, applying
duke@435	907	// the given oop closure to (possibly) all objects found. The
duke@435	908	// given oop closure may or may not be the same as the oop
duke@435	909	// closure with which this closure was created, as it may
duke@435	910	// be a filtering closure which makes use of the _boundary.
duke@435	911	// We offer two signatures, so the FilteringClosure static type is
duke@435	912	// apparent.
duke@435	913	virtual void walk_mem_region_with_cl(MemRegion mr,
duke@435	914	HeapWord* bottom, HeapWord* top,
duke@435	915	OopClosure* cl) = 0;
duke@435	916	virtual void walk_mem_region_with_cl(MemRegion mr,
duke@435	917	HeapWord* bottom, HeapWord* top,
duke@435	918	FilteringClosure* cl) = 0;
duke@435	919
duke@435	920	public:
duke@435	921	Filtering_DCTOC(Space* sp, OopClosure* cl,
duke@435	922	CardTableModRefBS::PrecisionStyle precision,
duke@435	923	HeapWord* boundary) :
duke@435	924	DirtyCardToOopClosure(sp, cl, precision, boundary) {}
duke@435	925	};
duke@435	926
duke@435	927	// A dirty card to oop closure for contiguous spaces
duke@435	928	// (ContiguousSpace and sub-classes).
duke@435	929	// It is a FilteringClosure, as defined above, and it knows:
duke@435	930	//
duke@435	931	// 1. That the actual top of any area in a memory region
duke@435	932	// contained by the space is bounded by the end of the contiguous
duke@435	933	// region of the space.
duke@435	934	// 2. That the space is really made up of objects and not just
duke@435	935	// blocks.
duke@435	936
duke@435	937	class ContiguousSpaceDCTOC : public Filtering_DCTOC {
duke@435	938	protected:
duke@435	939	// Overrides.
duke@435	940	HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);
duke@435	941
duke@435	942	virtual void walk_mem_region_with_cl(MemRegion mr,
duke@435	943	HeapWord* bottom, HeapWord* top,
duke@435	944	OopClosure* cl);
duke@435	945	virtual void walk_mem_region_with_cl(MemRegion mr,
duke@435	946	HeapWord* bottom, HeapWord* top,
duke@435	947	FilteringClosure* cl);
duke@435	948
duke@435	949	public:
duke@435	950	ContiguousSpaceDCTOC(ContiguousSpace* sp, OopClosure* cl,
duke@435	951	CardTableModRefBS::PrecisionStyle precision,
duke@435	952	HeapWord* boundary) :
duke@435	953	Filtering_DCTOC(sp, cl, precision, boundary)
duke@435	954	{}
duke@435	955	};
duke@435	956
duke@435	957
duke@435	958	// Class EdenSpace describes eden-space in new generation.
duke@435	959
duke@435	960	class DefNewGeneration;
duke@435	961
duke@435	962	class EdenSpace : public ContiguousSpace {
duke@435	963	friend class VMStructs;
duke@435	964	private:
duke@435	965	DefNewGeneration* _gen;
duke@435	966
duke@435	967	// _soft_end is used as a soft limit on allocation. As soft limits are
duke@435	968	// reached, the slow-path allocation code can invoke other actions and then
duke@435	969	// adjust _soft_end up to a new soft limit or to end().
duke@435	970	HeapWord* _soft_end;
duke@435	971
duke@435	972	public:
duke@435	973	EdenSpace(DefNewGeneration* gen) : _gen(gen) { _soft_end = NULL; }
duke@435	974
duke@435	975	// Get/set just the 'soft' limit.
duke@435	976	HeapWord* soft_end() { return _soft_end; }
duke@435	977	HeapWord** soft_end_addr() { return &_soft_end; }
duke@435	978	void set_soft_end(HeapWord* value) { _soft_end = value; }
duke@435	979
duke@435	980	// Override.
duke@435	981	void clear();
duke@435	982
duke@435	983	// Set both the 'hard' and 'soft' limits (_end and _soft_end).
duke@435	984	void set_end(HeapWord* value) {
duke@435	985	set_soft_end(value);
duke@435	986	ContiguousSpace::set_end(value);
duke@435	987	}
duke@435	988
duke@435	989	// Allocation (return NULL if full)
duke@435	990	HeapWord* allocate(size_t word_size);
duke@435	991	HeapWord* par_allocate(size_t word_size);
duke@435	992	};
duke@435	993
duke@435	994	// Class ConcEdenSpace extends EdenSpace for the sake of safe
duke@435	995	// allocation while soft-end is being modified concurrently
duke@435	996
duke@435	997	class ConcEdenSpace : public EdenSpace {
duke@435	998	public:
duke@435	999	ConcEdenSpace(DefNewGeneration* gen) : EdenSpace(gen) { }
duke@435	1000
duke@435	1001	// Allocation (return NULL if full)
duke@435	1002	HeapWord* par_allocate(size_t word_size);
duke@435	1003	};
duke@435	1004
duke@435	1005
duke@435	1006	// A ContigSpace that Supports an efficient "block_start" operation via
duke@435	1007	// a BlockOffsetArray (whose BlockOffsetSharedArray may be shared with
duke@435	1008	// other spaces.) This is the abstract base class for old generation
duke@435	1009	// (tenured, perm) spaces.
duke@435	1010
duke@435	1011	class OffsetTableContigSpace: public ContiguousSpace {
duke@435	1012	friend class VMStructs;
duke@435	1013	protected:
duke@435	1014	BlockOffsetArrayContigSpace _offsets;
duke@435	1015	Mutex _par_alloc_lock;
duke@435	1016
duke@435	1017	public:
duke@435	1018	// Constructor
duke@435	1019	OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
duke@435	1020	MemRegion mr);
duke@435	1021
duke@435	1022	void set_bottom(HeapWord* value);
duke@435	1023	void set_end(HeapWord* value);
duke@435	1024
ysr@777	1025	virtual void initialize(MemRegion mr, bool clear_space);
duke@435	1026	void clear();
duke@435	1027
ysr@777	1028	inline HeapWord* block_start_const(const void* p) const;
duke@435	1029
duke@435	1030	// Add offset table update.
duke@435	1031	virtual inline HeapWord* allocate(size_t word_size);
duke@435	1032	inline HeapWord* par_allocate(size_t word_size);
duke@435	1033
duke@435	1034	// MarkSweep support phase3
duke@435	1035	virtual HeapWord* initialize_threshold();
duke@435	1036	virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
duke@435	1037
duke@435	1038	virtual void print_on(outputStream* st) const;
duke@435	1039
duke@435	1040	// Debugging
duke@435	1041	void verify(bool allow_dirty) const;
duke@435	1042
duke@435	1043	// Shared space support
duke@435	1044	void serialize_block_offset_array_offsets(SerializeOopClosure* soc);
duke@435	1045	};
duke@435	1046
duke@435	1047
duke@435	1048	// Class TenuredSpace is used by TenuredGeneration
duke@435	1049
duke@435	1050	class TenuredSpace: public OffsetTableContigSpace {
duke@435	1051	friend class VMStructs;
duke@435	1052	protected:
duke@435	1053	// Mark sweep support
duke@435	1054	int allowed_dead_ratio() const;
duke@435	1055	public:
duke@435	1056	// Constructor
duke@435	1057	TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray,
duke@435	1058	MemRegion mr) :
duke@435	1059	OffsetTableContigSpace(sharedOffsetArray, mr) {}
duke@435	1060	};
duke@435	1061
duke@435	1062
duke@435	1063	// Class ContigPermSpace is used by CompactingPermGen
duke@435	1064
duke@435	1065	class ContigPermSpace: public OffsetTableContigSpace {
duke@435	1066	friend class VMStructs;
duke@435	1067	protected:
duke@435	1068	// Mark sweep support
duke@435	1069	int allowed_dead_ratio() const;
duke@435	1070	public:
duke@435	1071	// Constructor
duke@435	1072	ContigPermSpace(BlockOffsetSharedArray* sharedOffsetArray, MemRegion mr) :
duke@435	1073	OffsetTableContigSpace(sharedOffsetArray, mr) {}
duke@435	1074	};