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 void Metachunk::mangle() {
102 // Mangle the payload of the chunk and not the links that
103 // maintain list of chunks.
104 HeapWord* start = (HeapWord*)(bottom() + overhead());
105 size_t size = word_size() - overhead();
106 Copy::fill_to_words(start, size, metadata_chunk_initialize);
107 }
108 #endif // PRODUCT
109
110 void Metachunk::verify() {
111 #ifdef ASSERT
112 // Cannot walk through the blocks unless the blocks have
113 // headers with sizes.
114 assert(bottom() <= _top &&
115 _top <= (MetaWord*)end(),
116 "Chunk has been smashed");
117 #endif
118 return;
119 }
120
121 /////////////// Unit tests ///////////////
122
123 #ifndef PRODUCT
124
125 class TestMetachunk {
126 public:
127 static void test() {
128 size_t size = 2 * 1024 * 1024;
129 void* memory = malloc(size);
130 assert(memory != NULL, "Failed to malloc 2MB");
131
132 Metachunk* metachunk = ::new (memory) Metachunk(size / BytesPerWord, NULL);
133
134 assert(metachunk->bottom() == (MetaWord*)metachunk, "assert");
135 assert(metachunk->end() == (uintptr_t*)metachunk + metachunk->size(), "assert");
136
137 // Check sizes
138 assert(metachunk->size() == metachunk->word_size(), "assert");
139 assert(metachunk->word_size() == pointer_delta(metachunk->end(), metachunk->bottom(),
140 sizeof(MetaWord*)), "assert");
141
142 // Check usage
143 assert(metachunk->used_word_size() == metachunk->overhead(), "assert");
144 assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
145 assert(metachunk->top() == metachunk->initial_top(), "assert");
146 assert(metachunk->is_empty(), "assert");
147
148 // Allocate
149 size_t alloc_size = 64; // Words
150 assert(is_size_aligned(alloc_size, Metachunk::object_alignment()), "assert");
151
152 MetaWord* mem = metachunk->allocate(alloc_size);
153
154 // Check post alloc
155 assert(mem == metachunk->initial_top(), "assert");
156 assert(mem + alloc_size == metachunk->top(), "assert");
157 assert(metachunk->used_word_size() == metachunk->overhead() + alloc_size, "assert");
158 assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
159 assert(!metachunk->is_empty(), "assert");
160
161 // Clear chunk
162 metachunk->reset_empty();
163
164 // Check post clear
165 assert(metachunk->used_word_size() == metachunk->overhead(), "assert");
166 assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
167 assert(metachunk->top() == metachunk->initial_top(), "assert");
168 assert(metachunk->is_empty(), "assert");
169
170 free(memory);
171 }
172 };
173
174 void TestMetachunk_test() {
175 TestMetachunk::test();
176 }
177
178 #endif