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src/share/vm/memory/cardTableRS.hpp@0bfd3fb24150 (annotated)

src/share/vm/memory/cardTableRS.hpp

Tue, 13 Apr 2010 13:52:10 -0700

author

jmasa

date

Tue, 13 Apr 2010 13:52:10 -0700

changeset 1822

0bfd3fb24150

parent 791

1ee8caae33af

child 1907

c18cbe5936b8

permissions

-rw-r--r--

6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
Summary: Ensure a full GC that clears SoftReferences before throwing an out-of-memory
Reviewed-by: ysr, jcoomes

duke@435	1	/*
xdono@631	2	* Copyright 2001-2008 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	class Space;
duke@435	26	class OopsInGenClosure;
duke@435	27	class DirtyCardToOopClosure;
duke@435	28
duke@435	29	// This kind of "GenRemSet" uses a card table both as shared data structure
duke@435	30	// for a mod ref barrier set and for the rem set information.
duke@435	31
duke@435	32	class CardTableRS: public GenRemSet {
duke@435	33	friend class VMStructs;
duke@435	34	// Below are private classes used in impl.
duke@435	35	friend class VerifyCTSpaceClosure;
duke@435	36	friend class ClearNoncleanCardWrapper;
duke@435	37
duke@435	38	static jbyte clean_card_val() {
duke@435	39	return CardTableModRefBS::clean_card;
duke@435	40	}
duke@435	41
duke@435	42	static bool
duke@435	43	card_is_dirty_wrt_gen_iter(jbyte cv) {
duke@435	44	return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv);
duke@435	45	}
duke@435	46
ysr@777	47	CardTableModRefBSForCTRS* _ct_bs;
duke@435	48
duke@435	49	virtual void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
duke@435	50
duke@435	51	void verify_space(Space* s, HeapWord* gen_start);
duke@435	52
duke@435	53	enum ExtendedCardValue {
duke@435	54	youngergen_card = CardTableModRefBS::CT_MR_BS_last_reserved + 1,
duke@435	55	// These are for parallel collection.
duke@435	56	// There are three P (parallel) youngergen card values. In general, this
duke@435	57	// needs to be more than the number of generations (including the perm
duke@435	58	// gen) that might have younger_refs_do invoked on them separately. So
duke@435	59	// if we add more gens, we have to add more values.
duke@435	60	youngergenP1_card = CardTableModRefBS::CT_MR_BS_last_reserved + 2,
duke@435	61	youngergenP2_card = CardTableModRefBS::CT_MR_BS_last_reserved + 3,
duke@435	62	youngergenP3_card = CardTableModRefBS::CT_MR_BS_last_reserved + 4,
duke@435	63	cur_youngergen_and_prev_nonclean_card =
duke@435	64	CardTableModRefBS::CT_MR_BS_last_reserved + 5
duke@435	65	};
duke@435	66
duke@435	67	// An array that contains, for each generation, the card table value last
duke@435	68	// used as the current value for a younger_refs_do iteration of that
duke@435	69	// portion of the table. (The perm gen is index 0; other gens are at
duke@435	70	// their level plus 1. They youngest gen is in the table, but will
duke@435	71	// always have the value "clean_card".)
duke@435	72	jbyte* _last_cur_val_in_gen;
duke@435	73
duke@435	74	jbyte _cur_youngergen_card_val;
duke@435	75
ysr@777	76	int _regions_to_iterate;
ysr@777	77
duke@435	78	jbyte cur_youngergen_card_val() {
duke@435	79	return _cur_youngergen_card_val;
duke@435	80	}
duke@435	81	void set_cur_youngergen_card_val(jbyte v) {
duke@435	82	_cur_youngergen_card_val = v;
duke@435	83	}
duke@435	84	bool is_prev_youngergen_card_val(jbyte v) {
duke@435	85	return
duke@435	86	youngergen_card <= v &&
duke@435	87	v < cur_youngergen_and_prev_nonclean_card &&
duke@435	88	v != _cur_youngergen_card_val;
duke@435	89	}
duke@435	90	// Return a youngergen_card_value that is not currently in use.
duke@435	91	jbyte find_unused_youngergenP_card_value();
duke@435	92
duke@435	93	public:
duke@435	94	CardTableRS(MemRegion whole_heap, int max_covered_regions);
duke@435	95
duke@435	96	// *** GenRemSet functions.
duke@435	97	GenRemSet::Name rs_kind() { return GenRemSet::CardTable; }
duke@435	98
duke@435	99	CardTableRS* as_CardTableRS() { return this; }
duke@435	100
ysr@777	101	CardTableModRefBS* ct_bs() { return _ct_bs; }
duke@435	102
duke@435	103	// Override.
duke@435	104	void prepare_for_younger_refs_iterate(bool parallel);
duke@435	105
duke@435	106	// Card table entries are cleared before application; "blk" is
duke@435	107	// responsible for dirtying if the oop is still older-to-younger after
duke@435	108	// closure application.
duke@435	109	void younger_refs_iterate(Generation* g, OopsInGenClosure* blk);
duke@435	110
coleenp@548	111	void inline_write_ref_field_gc(void* field, oop new_val) {
ysr@777	112	jbyte* byte = _ct_bs->byte_for(field);
duke@435	113	*byte = youngergen_card;
duke@435	114	}
coleenp@548	115	void write_ref_field_gc_work(void* field, oop new_val) {
duke@435	116	inline_write_ref_field_gc(field, new_val);
duke@435	117	}
duke@435	118
duke@435	119	// Override. Might want to devirtualize this in the same fashion as
duke@435	120	// above. Ensures that the value of the card for field says that it's
duke@435	121	// a younger card in the current collection.
coleenp@548	122	virtual void write_ref_field_gc_par(void* field, oop new_val);
duke@435	123
duke@435	124	void resize_covered_region(MemRegion new_region);
duke@435	125
duke@435	126	bool is_aligned(HeapWord* addr) {
ysr@777	127	return _ct_bs->is_card_aligned(addr);
duke@435	128	}
duke@435	129
duke@435	130	void verify();
jmasa@441	131	void verify_aligned_region_empty(MemRegion mr);
duke@435	132
ysr@777	133	void clear(MemRegion mr) { _ct_bs->clear(mr); }
duke@435	134	void clear_into_younger(Generation* gen, bool clear_perm);
duke@435	135
ysr@777	136	void invalidate(MemRegion mr, bool whole_heap = false) {
ysr@777	137	_ct_bs->invalidate(mr, whole_heap);
ysr@777	138	}
duke@435	139	void invalidate_or_clear(Generation* gen, bool younger, bool perm);
duke@435	140
duke@435	141	static uintx ct_max_alignment_constraint() {
duke@435	142	return CardTableModRefBS::ct_max_alignment_constraint();
duke@435	143	}
duke@435	144
ysr@777	145	jbyte* byte_for(void* p) { return _ct_bs->byte_for(p); }
ysr@777	146	jbyte* byte_after(void* p) { return _ct_bs->byte_after(p); }
ysr@777	147	HeapWord* addr_for(jbyte* p) { return _ct_bs->addr_for(p); }
duke@435	148
duke@435	149	bool is_prev_nonclean_card_val(jbyte v) {
duke@435	150	return
duke@435	151	youngergen_card <= v &&
duke@435	152	v <= cur_youngergen_and_prev_nonclean_card &&
duke@435	153	v != _cur_youngergen_card_val;
duke@435	154	}
duke@435	155
duke@435	156	static bool youngergen_may_have_been_dirty(jbyte cv) {
duke@435	157	return cv == CardTableRS::cur_youngergen_and_prev_nonclean_card;
duke@435	158	}
duke@435	159
duke@435	160	};