1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)mutableSpace.cpp 1.22 07/05/05 17:05:35 JVM"
3 #endif
4 /*
5 * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 # include "incls/_precompiled.incl"
29 # include "incls/_mutableSpace.cpp.incl"
30
31 MutableSpace::MutableSpace(): ImmutableSpace(), _top(NULL) {
32 _mangler = new MutableSpaceMangler(this);
33 }
34
35 MutableSpace::~MutableSpace() {
36 delete _mangler;
37 }
38
39 void MutableSpace::initialize(MemRegion mr,
40 bool clear_space,
41 bool mangle_space) {
42 HeapWord* bottom = mr.start();
43 HeapWord* end = mr.end();
44
45 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
46 "invalid space boundaries");
47 set_bottom(bottom);
48 set_end(end);
49
50 if (clear_space) {
51 clear(mangle_space);
52 }
53 }
54
55 void MutableSpace::clear(bool mangle_space) {
56 set_top(bottom());
57 if (ZapUnusedHeapArea && mangle_space) {
58 mangle_unused_area();
59 }
60 }
61
62 #ifndef PRODUCT
63 void MutableSpace::check_mangled_unused_area(HeapWord* limit) {
64 mangler()->check_mangled_unused_area(limit);
65 }
66
67 void MutableSpace::check_mangled_unused_area_complete() {
68 mangler()->check_mangled_unused_area_complete();
69 }
70
71 // Mangle only the unused space that has not previously
72 // been mangled and that has not been allocated since being
73 // mangled.
74 void MutableSpace::mangle_unused_area() {
75 mangler()->mangle_unused_area();
76 }
77
78 void MutableSpace::mangle_unused_area_complete() {
79 mangler()->mangle_unused_area_complete();
80 }
81
82 void MutableSpace::mangle_region(MemRegion mr) {
83 SpaceMangler::mangle_region(mr);
84 }
85
86 void MutableSpace::set_top_for_allocations(HeapWord* v) {
87 mangler()->set_top_for_allocations(v);
88 }
89
90 void MutableSpace::set_top_for_allocations() {
91 mangler()->set_top_for_allocations(top());
92 }
93 #endif
94
95 // This version requires locking. */
96 HeapWord* MutableSpace::allocate(size_t size) {
97 assert(Heap_lock->owned_by_self() ||
98 (SafepointSynchronize::is_at_safepoint() &&
99 Thread::current()->is_VM_thread()),
100 "not locked");
101 HeapWord* obj = top();
102 if (pointer_delta(end(), obj) >= size) {
103 HeapWord* new_top = obj + size;
104 set_top(new_top);
105 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
106 "checking alignment");
107 return obj;
108 } else {
109 return NULL;
110 }
111 }
112
113 // This version is lock-free.
114 HeapWord* MutableSpace::cas_allocate(size_t size) {
115 do {
116 HeapWord* obj = top();
117 if (pointer_delta(end(), obj) >= size) {
118 HeapWord* new_top = obj + size;
119 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
120 // result can be one of two:
121 // the old top value: the exchange succeeded
122 // otherwise: the new value of the top is returned.
123 if (result != obj) {
124 continue; // another thread beat us to the allocation, try again
125 }
126 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
127 "checking alignment");
128 return obj;
129 } else {
130 return NULL;
131 }
132 } while (true);
133 }
134
135 // Try to deallocate previous allocation. Returns true upon success.
136 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
137 HeapWord* expected_top = obj + size;
138 return (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top;
139 }
140
141 void MutableSpace::oop_iterate(OopClosure* cl) {
142 HeapWord* obj_addr = bottom();
143 HeapWord* t = top();
144 // Could call objects iterate, but this is easier.
145 while (obj_addr < t) {
146 obj_addr += oop(obj_addr)->oop_iterate(cl);
147 }
148 }
149
150 void MutableSpace::object_iterate(ObjectClosure* cl) {
151 HeapWord* p = bottom();
152 while (p < top()) {
153 cl->do_object(oop(p));
154 p += oop(p)->size();
155 }
156 }
157
158 void MutableSpace::print_short() const { print_short_on(tty); }
159 void MutableSpace::print_short_on( outputStream* st) const {
160 st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
161 (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
162 }
163
164 void MutableSpace::print() const { print_on(tty); }
165 void MutableSpace::print_on(outputStream* st) const {
166 MutableSpace::print_short_on(st);
167 st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",
168 bottom(), top(), end());
169 }
170
171 void MutableSpace::verify(bool allow_dirty) {
172 HeapWord* p = bottom();
173 HeapWord* t = top();
174 HeapWord* prev_p = NULL;
175 while (p < t) {
176 oop(p)->verify();
177 prev_p = p;
178 p += oop(p)->size();
179 }
180 guarantee(p == top(), "end of last object must match end of space");
181 }