1 /*
2 * Copyright (c) 1997, 2003, 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 // The resource area holds temporary data structures in the VM.
26 // The actual allocation areas are thread local. Typical usage:
27 //
28 // ...
29 // {
30 // ResourceMark rm;
31 // int foo[] = NEW_RESOURCE_ARRAY(int, 64);
32 // ...
33 // }
34 // ...
35
36 //------------------------------ResourceArea-----------------------------------
37 // A ResourceArea is an Arena that supports safe usage of ResourceMark.
38 class ResourceArea: public Arena {
39 friend class ResourceMark;
40 friend class DeoptResourceMark;
41 debug_only(int _nesting;) // current # of nested ResourceMarks
42 debug_only(static int _warned;) // to suppress multiple warnings
43
44 public:
45 ResourceArea() {
46 debug_only(_nesting = 0;)
47 }
48
49 ResourceArea(size_t init_size) : Arena(init_size) {
50 debug_only(_nesting = 0;);
51 }
52
53 char* allocate_bytes(size_t size) {
54 #ifdef ASSERT
55 if (_nesting < 1 && !_warned++)
56 fatal("memory leak: allocating without ResourceMark");
57 if (UseMallocOnly) {
58 // use malloc, but save pointer in res. area for later freeing
59 char** save = (char**)internal_malloc_4(sizeof(char*));
60 return (*save = (char*)os::malloc(size));
61 }
62 #endif
63 return (char*)Amalloc(size);
64 }
65
66 debug_only(int nesting() const { return _nesting; });
67 };
68
69
70 //------------------------------ResourceMark-----------------------------------
71 // A resource mark releases all resources allocated after it was constructed
72 // when the destructor is called. Typically used as a local variable.
73 class ResourceMark: public StackObj {
74 protected:
75 ResourceArea *_area; // Resource area to stack allocate
76 Chunk *_chunk; // saved arena chunk
77 char *_hwm, *_max;
78 NOT_PRODUCT(size_t _size_in_bytes;)
79
80 void initialize(Thread *thread) {
81 _area = thread->resource_area();
82 _chunk = _area->_chunk;
83 _hwm = _area->_hwm;
84 _max= _area->_max;
85 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
86 debug_only(_area->_nesting++;)
87 assert( _area->_nesting > 0, "must stack allocate RMs" );
88 }
89
90 public:
91
92 #ifndef ASSERT
93 ResourceMark(Thread *thread) {
94 assert(thread == Thread::current(), "not the current thread");
95 initialize(thread);
96 }
97 #else
98 ResourceMark(Thread *thread);
99 #endif // ASSERT
100
101 ResourceMark() { initialize(Thread::current()); }
102
103 ResourceMark( ResourceArea *r ) :
104 _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {
105 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
106 debug_only(_area->_nesting++;)
107 assert( _area->_nesting > 0, "must stack allocate RMs" );
108 }
109
110 void reset_to_mark() {
111 if (UseMallocOnly) free_malloced_objects();
112
113 if( _chunk->next() ) // Delete later chunks
114 _chunk->next_chop();
115 _area->_chunk = _chunk; // Roll back arena to saved chunk
116 _area->_hwm = _hwm;
117 _area->_max = _max;
118
119 // clear out this chunk (to detect allocation bugs)
120 if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);
121 _area->set_size_in_bytes(size_in_bytes());
122 }
123
124 ~ResourceMark() {
125 assert( _area->_nesting > 0, "must stack allocate RMs" );
126 debug_only(_area->_nesting--;)
127 reset_to_mark();
128 }
129
130
131 private:
132 void free_malloced_objects() PRODUCT_RETURN;
133 size_t size_in_bytes() NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;
134 };
135
136 //------------------------------DeoptResourceMark-----------------------------------
137 // A deopt resource mark releases all resources allocated after it was constructed
138 // when the destructor is called. Typically used as a local variable. It differs
139 // from a typical resource more in that it is C-Heap allocated so that deoptimization
140 // can use data structures that are arena based but are not amenable to vanilla
141 // ResourceMarks because deoptimization can not use a stack allocated mark. During
142 // deoptimization we go thru the following steps:
143 //
144 // 0: start in assembly stub and call either uncommon_trap/fetch_unroll_info
145 // 1: create the vframeArray (contains pointers to Resource allocated structures)
146 // This allocates the DeoptResourceMark.
147 // 2: return to assembly stub and remove stub frame and deoptee frame and create
148 // the new skeletal frames.
149 // 3: push new stub frame and call unpack_frames
150 // 4: retrieve information from the vframeArray to populate the skeletal frames
151 // 5: release the DeoptResourceMark
152 // 6: return to stub and eventually to interpreter
153 //
154 // With old style eager deoptimization the vframeArray was created by the vmThread there
155 // was no way for the vframeArray to contain resource allocated objects and so
156 // a complex set of data structures to simulate an array of vframes in CHeap memory
157 // was used. With new style lazy deoptimization the vframeArray is created in the
158 // the thread that will use it and we can use a much simpler scheme for the vframeArray
159 // leveraging existing data structures if we simply create a way to manage this one
160 // special need for a ResourceMark. If ResourceMark simply inherited from CHeapObj
161 // then existing ResourceMarks would work fine since no one use new to allocate them
162 // and they would be stack allocated. This leaves open the possibilty of accidental
163 // misuse so we simple duplicate the ResourceMark functionality here.
164
165 class DeoptResourceMark: public CHeapObj {
166 protected:
167 ResourceArea *_area; // Resource area to stack allocate
168 Chunk *_chunk; // saved arena chunk
169 char *_hwm, *_max;
170 NOT_PRODUCT(size_t _size_in_bytes;)
171
172 void initialize(Thread *thread) {
173 _area = thread->resource_area();
174 _chunk = _area->_chunk;
175 _hwm = _area->_hwm;
176 _max= _area->_max;
177 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
178 debug_only(_area->_nesting++;)
179 assert( _area->_nesting > 0, "must stack allocate RMs" );
180 }
181
182 public:
183
184 #ifndef ASSERT
185 DeoptResourceMark(Thread *thread) {
186 assert(thread == Thread::current(), "not the current thread");
187 initialize(thread);
188 }
189 #else
190 DeoptResourceMark(Thread *thread);
191 #endif // ASSERT
192
193 DeoptResourceMark() { initialize(Thread::current()); }
194
195 DeoptResourceMark( ResourceArea *r ) :
196 _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {
197 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
198 debug_only(_area->_nesting++;)
199 assert( _area->_nesting > 0, "must stack allocate RMs" );
200 }
201
202 void reset_to_mark() {
203 if (UseMallocOnly) free_malloced_objects();
204
205 if( _chunk->next() ) // Delete later chunks
206 _chunk->next_chop();
207 _area->_chunk = _chunk; // Roll back arena to saved chunk
208 _area->_hwm = _hwm;
209 _area->_max = _max;
210
211 // clear out this chunk (to detect allocation bugs)
212 if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);
213 _area->set_size_in_bytes(size_in_bytes());
214 }
215
216 ~DeoptResourceMark() {
217 assert( _area->_nesting > 0, "must stack allocate RMs" );
218 debug_only(_area->_nesting--;)
219 reset_to_mark();
220 }
221
222
223 private:
224 void free_malloced_objects() PRODUCT_RETURN;
225 size_t size_in_bytes() NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;
226 };