1 /*
2 * Copyright (c) 1998, 2002, 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 // All classes in the virtual machine must be subclassed
26 // by one of the following allocation classes:
27 //
28 //
29 // For objects allocated in the C-heap (managed by: free & malloc).
30 // - CHeapObj
31 //
32 //
33 // For embedded objects.
34 // - ValueObj
35 //
36 // For classes used as name spaces.
37 // - AllStatic
38 //
39
40 class CHeapObj {
41 public:
42 void* operator new(size_t size);
43 void operator delete(void* p);
44 void* new_array(size_t size);
45 };
46
47
48 // Base class for objects used as value objects.
49 // Calling new or delete will result in fatal error.
50
51 class ValueObj {
52 public:
53 void* operator new(size_t size);
54 void operator delete(void* p);
55 };
56
57 // Base class for classes that constitute name spaces.
58
59 class AllStatic {
60 public:
61 void* operator new(size_t size);
62 void operator delete(void* p);
63 };
64
65
66 //------------------------------Chunk------------------------------------------
67 // Linked list of raw memory chunks
68 class Chunk: public CHeapObj {
69 public:
70 void* operator new(size_t size, size_t length);
71 void operator delete(void* p, size_t length);
72 Chunk(size_t length);
73
74 enum {
75 init_size = 1*1024, // Size of first chunk
76 size = 32*1024 // Default size of an Arena chunk (following the first)
77 };
78 Chunk* _next; // Next Chunk in list
79 size_t _len; // Size of this Chunk
80
81 void chop(); // Chop this chunk
82 void next_chop(); // Chop next chunk
83
84 // Boundaries of data area (possibly unused)
85 char* bottom() const { return ((char*) this) + sizeof(Chunk); }
86 char* top() const { return bottom() + _len; }
87 };
88
89
90 //------------------------------Arena------------------------------------------
91 // Fast allocation of memory
92 class Arena: public CHeapObj {
93 protected:
94 friend class ResourceMark;
95 friend class HandleMark;
96 friend class NoHandleMark;
97 Chunk *_first; // First chunk
98 Chunk *_chunk; // current chunk
99 char *_hwm, *_max; // High water mark and max in current chunk
100 void* grow(size_t x); // Get a new Chunk of at least size x
101 size_t _size_in_bytes; // Size of arena (used for memory usage tracing)
102 public:
103 Arena();
104 Arena(size_t init_size);
105 Arena(Arena *old);
106 ~Arena() { _first->chop(); }
107 char* hwm() const { return _hwm; }
108
109 // Fast allocate in the arena. Common case is: pointer test + increment.
110 void* Amalloc(size_t x) {
111 #ifdef _LP64
112 x = (x + (8-1)) & ((unsigned)(-8));
113 #else
114 x = (x + (4-1)) & ((unsigned)(-4));
115 #endif
116 if (_hwm + x > _max) {
117 return grow(x);
118 } else {
119 char *old = _hwm;
120 _hwm += x;
121 return old;
122 }
123 }
124 // Further assume size is padded out to words
125 // Warning: in LP64, Amalloc_4 is really Amalloc_8
126 void *Amalloc_4(size_t x) {
127 assert( (x&(sizeof(char*)-1)) == 0, "misaligned size" );
128 if (_hwm + x > _max) {
129 return grow(x);
130 } else {
131 char *old = _hwm;
132 _hwm += x;
133 return old;
134 }
135 }
136
137 // Fast delete in area. Common case is: NOP (except for storage reclaimed)
138 void Afree(void *ptr, size_t size) {
139 if (((char*)ptr) + size == _hwm) _hwm = (char*)ptr;
140 }
141
142 void *Acalloc( size_t items, size_t x );
143 void *Arealloc( void *old_ptr, size_t old_size, size_t new_size );
144
145 // Reset this Arena to empty, and return this Arenas guts in a new Arena.
146 Arena *reset(void);
147
148 // Determine if pointer belongs to this Arena or not.
149 bool contains( const void *ptr ) const;
150
151 // Total of all chunks in use (not thread-safe)
152 size_t used() const;
153
154 // Total # of bytes used
155 size_t size_in_bytes() const { return _size_in_bytes; }
156 void set_size_in_bytes(size_t size) { _size_in_bytes = size; }
157 };