1 /*
2 * Copyright (c) 1997, 2011, 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 #ifndef SHARE_VM_MEMORY_RESOURCEAREA_HPP
26 #define SHARE_VM_MEMORY_RESOURCEAREA_HPP
27
28 #include "memory/allocation.hpp"
29 #ifdef TARGET_OS_FAMILY_linux
30 # include "thread_linux.inline.hpp"
31 #endif
32 #ifdef TARGET_OS_FAMILY_solaris
33 # include "thread_solaris.inline.hpp"
34 #endif
35 #ifdef TARGET_OS_FAMILY_windows
36 # include "thread_windows.inline.hpp"
37 #endif
38 #ifdef TARGET_OS_FAMILY_bsd
39 # include "thread_bsd.inline.hpp"
40 #endif
41
42 // The resource area holds temporary data structures in the VM.
43 // The actual allocation areas are thread local. Typical usage:
44 //
45 // ...
46 // {
47 // ResourceMark rm;
48 // int foo[] = NEW_RESOURCE_ARRAY(int, 64);
49 // ...
50 // }
51 // ...
52
53 //------------------------------ResourceArea-----------------------------------
54 // A ResourceArea is an Arena that supports safe usage of ResourceMark.
55 class ResourceArea: public Arena {
56 friend class ResourceMark;
57 friend class DeoptResourceMark;
58 friend class VMStructs;
59 debug_only(int _nesting;) // current # of nested ResourceMarks
60 debug_only(static int _warned;) // to suppress multiple warnings
61
62 public:
63 ResourceArea() {
64 debug_only(_nesting = 0;)
65 }
66
67 ResourceArea(size_t init_size) : Arena(init_size) {
68 debug_only(_nesting = 0;);
69 }
70
71 char* allocate_bytes(size_t size) {
72 #ifdef ASSERT
73 if (_nesting < 1 && !_warned++)
74 fatal("memory leak: allocating without ResourceMark");
75 if (UseMallocOnly) {
76 // use malloc, but save pointer in res. area for later freeing
77 char** save = (char**)internal_malloc_4(sizeof(char*));
78 return (*save = (char*)os::malloc(size));
79 }
80 #endif
81 return (char*)Amalloc(size);
82 }
83
84 debug_only(int nesting() const { return _nesting; });
85 };
86
87
88 //------------------------------ResourceMark-----------------------------------
89 // A resource mark releases all resources allocated after it was constructed
90 // when the destructor is called. Typically used as a local variable.
91 class ResourceMark: public StackObj {
92 protected:
93 ResourceArea *_area; // Resource area to stack allocate
94 Chunk *_chunk; // saved arena chunk
95 char *_hwm, *_max;
96 NOT_PRODUCT(size_t _size_in_bytes;)
97
98 void initialize(Thread *thread) {
99 _area = thread->resource_area();
100 _chunk = _area->_chunk;
101 _hwm = _area->_hwm;
102 _max= _area->_max;
103 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
104 debug_only(_area->_nesting++;)
105 assert( _area->_nesting > 0, "must stack allocate RMs" );
106 }
107
108 public:
109
110 #ifndef ASSERT
111 ResourceMark(Thread *thread) {
112 assert(thread == Thread::current(), "not the current thread");
113 initialize(thread);
114 }
115 #else
116 ResourceMark(Thread *thread);
117 #endif // ASSERT
118
119 ResourceMark() { initialize(Thread::current()); }
120
121 ResourceMark( ResourceArea *r ) :
122 _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {
123 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
124 debug_only(_area->_nesting++;)
125 assert( _area->_nesting > 0, "must stack allocate RMs" );
126 }
127
128 void reset_to_mark() {
129 if (UseMallocOnly) free_malloced_objects();
130
131 if( _chunk->next() ) // Delete later chunks
132 _chunk->next_chop();
133 _area->_chunk = _chunk; // Roll back arena to saved chunk
134 _area->_hwm = _hwm;
135 _area->_max = _max;
136
137 // clear out this chunk (to detect allocation bugs)
138 if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);
139 _area->set_size_in_bytes(size_in_bytes());
140 }
141
142 ~ResourceMark() {
143 assert( _area->_nesting > 0, "must stack allocate RMs" );
144 debug_only(_area->_nesting--;)
145 reset_to_mark();
146 }
147
148
149 private:
150 void free_malloced_objects() PRODUCT_RETURN;
151 size_t size_in_bytes() NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;
152 };
153
154 //------------------------------DeoptResourceMark-----------------------------------
155 // A deopt resource mark releases all resources allocated after it was constructed
156 // when the destructor is called. Typically used as a local variable. It differs
157 // from a typical resource more in that it is C-Heap allocated so that deoptimization
158 // can use data structures that are arena based but are not amenable to vanilla
159 // ResourceMarks because deoptimization can not use a stack allocated mark. During
160 // deoptimization we go thru the following steps:
161 //
162 // 0: start in assembly stub and call either uncommon_trap/fetch_unroll_info
163 // 1: create the vframeArray (contains pointers to Resource allocated structures)
164 // This allocates the DeoptResourceMark.
165 // 2: return to assembly stub and remove stub frame and deoptee frame and create
166 // the new skeletal frames.
167 // 3: push new stub frame and call unpack_frames
168 // 4: retrieve information from the vframeArray to populate the skeletal frames
169 // 5: release the DeoptResourceMark
170 // 6: return to stub and eventually to interpreter
171 //
172 // With old style eager deoptimization the vframeArray was created by the vmThread there
173 // was no way for the vframeArray to contain resource allocated objects and so
174 // a complex set of data structures to simulate an array of vframes in CHeap memory
175 // was used. With new style lazy deoptimization the vframeArray is created in the
176 // the thread that will use it and we can use a much simpler scheme for the vframeArray
177 // leveraging existing data structures if we simply create a way to manage this one
178 // special need for a ResourceMark. If ResourceMark simply inherited from CHeapObj
179 // then existing ResourceMarks would work fine since no one use new to allocate them
180 // and they would be stack allocated. This leaves open the possibilty of accidental
181 // misuse so we simple duplicate the ResourceMark functionality here.
182
183 class DeoptResourceMark: public CHeapObj {
184 protected:
185 ResourceArea *_area; // Resource area to stack allocate
186 Chunk *_chunk; // saved arena chunk
187 char *_hwm, *_max;
188 NOT_PRODUCT(size_t _size_in_bytes;)
189
190 void initialize(Thread *thread) {
191 _area = thread->resource_area();
192 _chunk = _area->_chunk;
193 _hwm = _area->_hwm;
194 _max= _area->_max;
195 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
196 debug_only(_area->_nesting++;)
197 assert( _area->_nesting > 0, "must stack allocate RMs" );
198 }
199
200 public:
201
202 #ifndef ASSERT
203 DeoptResourceMark(Thread *thread) {
204 assert(thread == Thread::current(), "not the current thread");
205 initialize(thread);
206 }
207 #else
208 DeoptResourceMark(Thread *thread);
209 #endif // ASSERT
210
211 DeoptResourceMark() { initialize(Thread::current()); }
212
213 DeoptResourceMark( ResourceArea *r ) :
214 _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {
215 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
216 debug_only(_area->_nesting++;)
217 assert( _area->_nesting > 0, "must stack allocate RMs" );
218 }
219
220 void reset_to_mark() {
221 if (UseMallocOnly) free_malloced_objects();
222
223 if( _chunk->next() ) // Delete later chunks
224 _chunk->next_chop();
225 _area->_chunk = _chunk; // Roll back arena to saved chunk
226 _area->_hwm = _hwm;
227 _area->_max = _max;
228
229 // clear out this chunk (to detect allocation bugs)
230 if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);
231 _area->set_size_in_bytes(size_in_bytes());
232 }
233
234 ~DeoptResourceMark() {
235 assert( _area->_nesting > 0, "must stack allocate RMs" );
236 debug_only(_area->_nesting--;)
237 reset_to_mark();
238 }
239
240
241 private:
242 void free_malloced_objects() PRODUCT_RETURN;
243 size_t size_in_bytes() NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;
244 };
245
246 #endif // SHARE_VM_MEMORY_RESOURCEAREA_HPP