1 /*
2 * Copyright (c) 2012, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "memory/allocation.hpp"
27 #include "memory/metachunk.hpp"
28 #include "utilities/copy.hpp"
29 #include "utilities/debug.hpp"
30
31 class VirtualSpaceNode;
32
33 const size_t metadata_chunk_initialize = 0xf7f7f7f7;
34
35 size_t Metachunk::object_alignment() {
36 // Must align pointers and sizes to 8,
37 // so that 64 bit types get correctly aligned.
38 const size_t alignment = 8;
39
40 // Make sure that the Klass alignment also agree.
41 STATIC_ASSERT(alignment == (size_t)KlassAlignmentInBytes);
42
43 return alignment;
44 }
45
46 size_t Metachunk::overhead() {
47 return align_size_up(sizeof(Metachunk), object_alignment()) / BytesPerWord;
48 }
49
50 // Metachunk methods
51
52 Metachunk::Metachunk(size_t word_size,
53 VirtualSpaceNode* container)
54 : Metabase<Metachunk>(word_size),
55 _top(NULL),
56 _container(container)
57 {
58 _top = initial_top();
59 #ifdef ASSERT
60 set_is_tagged_free(false);
61 size_t data_word_size = pointer_delta(end(),
62 _top,
63 sizeof(MetaWord));
64 Copy::fill_to_words((HeapWord*)_top,
65 data_word_size,
66 metadata_chunk_initialize);
67 #endif
68 }
69
70 MetaWord* Metachunk::allocate(size_t word_size) {
71 MetaWord* result = NULL;
72 // If available, bump the pointer to allocate.
73 if (free_word_size() >= word_size) {
74 result = _top;
75 _top = _top + word_size;
76 }
77 return result;
78 }
79
80 // _bottom points to the start of the chunk including the overhead.
81 size_t Metachunk::used_word_size() const {
82 return pointer_delta(_top, bottom(), sizeof(MetaWord));
83 }
84
85 size_t Metachunk::free_word_size() const {
86 return pointer_delta(end(), _top, sizeof(MetaWord));
87 }
88
89 void Metachunk::print_on(outputStream* st) const {
90 st->print_cr("Metachunk:"
91 " bottom " PTR_FORMAT " top " PTR_FORMAT
92 " end " PTR_FORMAT " size " SIZE_FORMAT,
93 p2i(bottom()), p2i(_top), p2i(end()), word_size());
94 if (Verbose) {
95 st->print_cr(" used " SIZE_FORMAT " free " SIZE_FORMAT,
96 used_word_size(), free_word_size());
97 }
98 }
99
100 #ifndef PRODUCT
101 static void overwrite_chunk_payload(Metachunk* chunk, juint wordValue) {
102 // Mangle the payload of the chunk and not the links that
103 // maintain list of chunks.
104 HeapWord* start = (HeapWord*)(chunk->bottom() + chunk->overhead());
105 size_t size = chunk->word_size() - chunk->overhead();
106 Copy::fill_to_words(start, size, wordValue);
107 }
108
109 void Metachunk::mangle() {
110 overwrite_chunk_payload(this, metadata_chunk_initialize);
111 }
112
113 void Metachunk::zap() {
114 overwrite_chunk_payload(this, badMetaWordVal);
115 }
116 #endif // PRODUCT
117
118 void Metachunk::verify() {
119 #ifdef ASSERT
120 // Cannot walk through the blocks unless the blocks have
121 // headers with sizes.
122 assert(bottom() <= _top &&
123 _top <= (MetaWord*)end(),
124 "Chunk has been smashed");
125 #endif
126 return;
127 }
128
129 /////////////// Unit tests ///////////////
130
131 #ifndef PRODUCT
132
133 class TestMetachunk {
134 public:
135 static void test() {
136 size_t size = 2 * 1024 * 1024;
137 void* memory = malloc(size);
138 assert(memory != NULL, "Failed to malloc 2MB");
139
140 Metachunk* metachunk = ::new (memory) Metachunk(size / BytesPerWord, NULL);
141
142 assert(metachunk->bottom() == (MetaWord*)metachunk, "assert");
143 assert(metachunk->end() == (uintptr_t*)metachunk + metachunk->size(), "assert");
144
145 // Check sizes
146 assert(metachunk->size() == metachunk->word_size(), "assert");
147 assert(metachunk->word_size() == pointer_delta(metachunk->end(), metachunk->bottom(),
148 sizeof(MetaWord*)), "assert");
149
150 // Check usage
151 assert(metachunk->used_word_size() == metachunk->overhead(), "assert");
152 assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
153 assert(metachunk->top() == metachunk->initial_top(), "assert");
154 assert(metachunk->is_empty(), "assert");
155
156 // Allocate
157 size_t alloc_size = 64; // Words
158 assert(is_size_aligned(alloc_size, Metachunk::object_alignment()), "assert");
159
160 MetaWord* mem = metachunk->allocate(alloc_size);
161
162 // Check post alloc
163 assert(mem == metachunk->initial_top(), "assert");
164 assert(mem + alloc_size == metachunk->top(), "assert");
165 assert(metachunk->used_word_size() == metachunk->overhead() + alloc_size, "assert");
166 assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
167 assert(!metachunk->is_empty(), "assert");
168
169 // Clear chunk
170 metachunk->reset_empty();
171
172 // Check post clear
173 assert(metachunk->used_word_size() == metachunk->overhead(), "assert");
174 assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
175 assert(metachunk->top() == metachunk->initial_top(), "assert");
176 assert(metachunk->is_empty(), "assert");
177
178 free(memory);
179 }
180 };
181
182 void TestMetachunk_test() {
183 TestMetachunk::test();
184 }
185
186 #endif