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

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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-1:000000000000 0:a61af66fc99e
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 # include "incls/_precompiled.incl"
26 # include "incls/_mutableSpace.cpp.incl"
27
28 void MutableSpace::initialize(MemRegion mr, bool clear_space) {
29 HeapWord* bottom = mr.start();
30 HeapWord* end = mr.end();
31
32 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
33 "invalid space boundaries");
34 set_bottom(bottom);
35 set_end(end);
36
37 if (clear_space) clear();
38 }
39
40 void MutableSpace::clear() {
41 set_top(bottom());
42 if (ZapUnusedHeapArea) mangle_unused_area();
43 }
44
45 // This version requires locking. */
46 HeapWord* MutableSpace::allocate(size_t size) {
47 assert(Heap_lock->owned_by_self() ||
48 (SafepointSynchronize::is_at_safepoint() &&
49 Thread::current()->is_VM_thread()),
50 "not locked");
51 HeapWord* obj = top();
52 if (pointer_delta(end(), obj) >= size) {
53 HeapWord* new_top = obj + size;
54 set_top(new_top);
55 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
56 "checking alignment");
57 return obj;
58 } else {
59 return NULL;
60 }
61 }
62
63 // This version is lock-free.
64 HeapWord* MutableSpace::cas_allocate(size_t size) {
65 do {
66 HeapWord* obj = top();
67 if (pointer_delta(end(), obj) >= size) {
68 HeapWord* new_top = obj + size;
69 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
70 // result can be one of two:
71 // the old top value: the exchange succeeded
72 // otherwise: the new value of the top is returned.
73 if (result != obj) {
74 continue; // another thread beat us to the allocation, try again
75 }
76 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
77 "checking alignment");
78 return obj;
79 } else {
80 return NULL;
81 }
82 } while (true);
83 }
84
85 // Try to deallocate previous allocation. Returns true upon success.
86 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
87 HeapWord* expected_top = obj + size;
88 return (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top;
89 }
90
91 void MutableSpace::oop_iterate(OopClosure* cl) {
92 HeapWord* obj_addr = bottom();
93 HeapWord* t = top();
94 // Could call objects iterate, but this is easier.
95 while (obj_addr < t) {
96 obj_addr += oop(obj_addr)->oop_iterate(cl);
97 }
98 }
99
100 void MutableSpace::object_iterate(ObjectClosure* cl) {
101 HeapWord* p = bottom();
102 while (p < top()) {
103 cl->do_object(oop(p));
104 p += oop(p)->size();
105 }
106 }
107
108 void MutableSpace::print_short() const { print_short_on(tty); }
109 void MutableSpace::print_short_on( outputStream* st) const {
110 st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
111 (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
112 }
113
114 void MutableSpace::print() const { print_on(tty); }
115 void MutableSpace::print_on(outputStream* st) const {
116 MutableSpace::print_short_on(st);
117 st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",
118 bottom(), top(), end());
119 }
120
121 void MutableSpace::verify(bool allow_dirty) const {
122 HeapWord* p = bottom();
123 HeapWord* t = top();
124 HeapWord* prev_p = NULL;
125 while (p < t) {
126 oop(p)->verify();
127 prev_p = p;
128 p += oop(p)->size();
129 }
130 guarantee(p == top(), "end of last object must match end of space");
131 }