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comparison src/share/vm/gc_implementation/shared/mutableSpace.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // A MutableSpace is a subtype of ImmutableSpace that supports the
26 // concept of allocation. This includes the concepts that a space may
27 // be only partially full, and the querry methods that go with such
28 // an assumption.
29 //
30 // Invariant: (ImmutableSpace +) bottom() <= top() <= end()
31 // top() is inclusive and end() is exclusive.
32
33 class MutableSpace: public ImmutableSpace {
34 friend class VMStructs;
35 protected:
36 HeapWord* _top;
37
38 public:
39 virtual ~MutableSpace() {}
40 MutableSpace() { _top = NULL; }
41 // Accessors
42 HeapWord* top() const { return _top; }
43 virtual void set_top(HeapWord* value) { _top = value; }
44
45 HeapWord** top_addr() { return &_top; }
46 HeapWord** end_addr() { return &_end; }
47
48 virtual void set_bottom(HeapWord* value) { _bottom = value; }
49 virtual void set_end(HeapWord* value) { _end = value; }
50
51 // Returns a subregion containing all objects in this space.
52 MemRegion used_region() { return MemRegion(bottom(), top()); }
53
54 // Initialization
55 virtual void initialize(MemRegion mr, bool clear_space);
56 virtual void clear();
57 virtual void update() { }
58 virtual void accumulate_statistics() { }
59
60 // Overwrites the unused portion of this space. Note that some collectors
61 // may use this "scratch" space during collections.
62 virtual void mangle_unused_area() {
63 mangle_region(MemRegion(_top, _end));
64 }
65 virtual void ensure_parsability() { }
66
67 void mangle_region(MemRegion mr) {
68 debug_only(Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord));
69 }
70
71 // Boolean querries.
72 bool is_empty() const { return used_in_words() == 0; }
73 bool not_empty() const { return used_in_words() > 0; }
74 bool contains(const void* p) const { return _bottom <= p && p < _end; }
75
76 // Size computations. Sizes are in bytes.
77 size_t used_in_bytes() const { return used_in_words() * HeapWordSize; }
78 size_t free_in_bytes() const { return free_in_words() * HeapWordSize; }
79
80 // Size computations. Sizes are in heapwords.
81 virtual size_t used_in_words() const { return pointer_delta(top(), bottom()); }
82 virtual size_t free_in_words() const { return pointer_delta(end(), top()); }
83 virtual size_t tlab_capacity(Thread* thr) const { return capacity_in_bytes(); }
84 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const { return free_in_bytes(); }
85
86 // Allocation (return NULL if full)
87 virtual HeapWord* allocate(size_t word_size);
88 virtual HeapWord* cas_allocate(size_t word_size);
89 // Optional deallocation. Used in NUMA-allocator.
90 bool cas_deallocate(HeapWord *obj, size_t size);
91
92 // Iteration.
93 void oop_iterate(OopClosure* cl);
94 void object_iterate(ObjectClosure* cl);
95
96 // Debugging
97 virtual void print() const;
98 virtual void print_on(outputStream* st) const;
99 virtual void print_short() const;
100 virtual void print_short_on(outputStream* st) const;
101 virtual void verify(bool allow_dirty) const;
102 };