Tue, 09 Oct 2012 10:09:34 -0700
7197424: update copyright year to match last edit in jdk8 hotspot repository
Summary: Update copyright year to 2012 for relevant files
Reviewed-by: dholmes, coleenp
1 /*
2 * Copyright (c) 1997, 2012, 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 */
25 #ifndef SHARE_VM_RUNTIME_HANDLES_HPP
26 #define SHARE_VM_RUNTIME_HANDLES_HPP
28 #include "oops/klass.hpp"
30 //------------------------------------------------------------------------------------------------------------------------
31 // In order to preserve oops during garbage collection, they should be
32 // allocated and passed around via Handles within the VM. A handle is
33 // simply an extra indirection allocated in a thread local handle area.
34 //
35 // A handle is a ValueObj, so it can be passed around as a value, can
36 // be used as a parameter w/o using &-passing, and can be returned as a
37 // return value.
38 //
39 // oop parameters and return types should be Handles whenever feasible.
40 //
41 // Handles are declared in a straight-forward manner, e.g.
42 //
43 // oop obj = ...;
44 // Handle h1(obj); // allocate new handle
45 // Handle h2(thread, obj); // faster allocation when current thread is known
46 // Handle h3; // declare handle only, no allocation occurs
47 // ...
48 // h3 = h1; // make h3 refer to same indirection as h1
49 // oop obj2 = h2(); // get handle value
50 // h1->print(); // invoking operation on oop
51 //
52 // Handles are specialized for different oop types to provide extra type
53 // information and avoid unnecessary casting. For each oop type xxxOop
54 // there is a corresponding handle called xxxHandle, e.g.
55 //
56 // oop Handle
57 // Method* methodHandle
58 // instanceOop instanceHandle
60 //------------------------------------------------------------------------------------------------------------------------
61 // Base class for all handles. Provides overloading of frequently
62 // used operators for ease of use.
64 class Handle VALUE_OBJ_CLASS_SPEC {
65 private:
66 oop* _handle;
68 protected:
69 oop obj() const { return _handle == NULL ? (oop)NULL : *_handle; }
70 oop non_null_obj() const { assert(_handle != NULL, "resolving NULL handle"); return *_handle; }
72 public:
73 // Constructors
74 Handle() { _handle = NULL; }
75 Handle(oop obj);
76 Handle(Thread* thread, oop obj);
78 // General access
79 oop operator () () const { return obj(); }
80 oop operator -> () const { return non_null_obj(); }
81 bool operator == (oop o) const { return obj() == o; }
82 bool operator == (const Handle& h) const { return obj() == h.obj(); }
84 // Null checks
85 bool is_null() const { return _handle == NULL; }
86 bool not_null() const { return _handle != NULL; }
88 // Debugging
89 void print() { obj()->print(); }
91 // Direct interface, use very sparingly.
92 // Used by JavaCalls to quickly convert handles and to create handles static data structures.
93 // Constructor takes a dummy argument to prevent unintentional type conversion in C++.
94 Handle(oop *handle, bool dummy) { _handle = handle; }
96 // Raw handle access. Allows easy duplication of Handles. This can be very unsafe
97 // since duplicates is only valid as long as original handle is alive.
98 oop* raw_value() { return _handle; }
99 static oop raw_resolve(oop *handle) { return handle == NULL ? (oop)NULL : *handle; }
100 };
102 // Specific Handles for different oop types
103 #define DEF_HANDLE(type, is_a) \
104 class type##Handle: public Handle { \
105 protected: \
106 type##Oop obj() const { return (type##Oop)Handle::obj(); } \
107 type##Oop non_null_obj() const { return (type##Oop)Handle::non_null_obj(); } \
108 \
109 public: \
110 /* Constructors */ \
111 type##Handle () : Handle() {} \
112 type##Handle (type##Oop obj) : Handle((oop)obj) { \
113 assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), \
114 "illegal type"); \
115 } \
116 type##Handle (Thread* thread, type##Oop obj) : Handle(thread, (oop)obj) { \
117 assert(SharedSkipVerify || is_null() || ((oop)obj)->is_a(), "illegal type"); \
118 } \
119 \
120 /* Operators for ease of use */ \
121 type##Oop operator () () const { return obj(); } \
122 type##Oop operator -> () const { return non_null_obj(); } \
123 };
126 DEF_HANDLE(instance , is_instance )
127 DEF_HANDLE(array , is_array )
128 DEF_HANDLE(objArray , is_objArray )
129 DEF_HANDLE(typeArray , is_typeArray )
131 //------------------------------------------------------------------------------------------------------------------------
133 // Metadata Handles. Unlike oop Handles these are needed to prevent metadata
134 // from being reclaimed by RedefineClasses.
136 // Specific Handles for different oop types
137 #define DEF_METADATA_HANDLE(name, type) \
138 class name##Handle; \
139 class name##Handle { \
140 type* _value; \
141 Thread* _thread; \
142 protected: \
143 type* obj() const { return _value; } \
144 type* non_null_obj() const { assert(_value != NULL, "resolving NULL _value"); return _value; } \
145 \
146 public: \
147 /* Constructors */ \
148 name##Handle () : _value(NULL), _thread(NULL) {} \
149 name##Handle (type* obj); \
150 name##Handle (Thread* thread, type* obj); \
151 \
152 name##Handle (const name##Handle &h); \
153 name##Handle& operator=(const name##Handle &s); \
154 \
155 /* Destructor */ \
156 ~name##Handle (); \
157 void remove(); \
158 \
159 /* Operators for ease of use */ \
160 type* operator () () const { return obj(); } \
161 type* operator -> () const { return non_null_obj(); } \
162 \
163 bool operator == (type* o) const { return obj() == o; } \
164 bool operator == (const name##Handle& h) const { return obj() == h.obj(); } \
165 \
166 /* Null checks */ \
167 bool is_null() const { return _value == NULL; } \
168 bool not_null() const { return _value != NULL; } \
169 };
172 DEF_METADATA_HANDLE(method, Method)
173 DEF_METADATA_HANDLE(constantPool, ConstantPool)
175 // Writing this class explicitly, since DEF_METADATA_HANDLE(klass) doesn't
176 // provide the necessary Klass* <-> Klass* conversions. This Klass
177 // could be removed when we don't have the Klass* typedef anymore.
178 class KlassHandle {
179 Klass* _value;
180 protected:
181 Klass* obj() const { return _value; }
182 Klass* non_null_obj() const { assert(_value != NULL, "resolving NULL _value"); return _value; }
184 public:
185 KlassHandle() : _value(NULL) {}
186 KlassHandle(const Klass* obj) : _value(const_cast<Klass *>(obj)) {};
187 KlassHandle(Thread* thread, const Klass* obj) : _value(const_cast<Klass *>(obj)) {};
189 Klass* operator () () const { return obj(); }
190 Klass* operator -> () const { return non_null_obj(); }
192 bool operator == (Klass* o) const { return obj() == o; }
193 bool operator == (const KlassHandle& h) const { return obj() == h.obj(); }
195 bool is_null() const { return _value == NULL; }
196 bool not_null() const { return _value != NULL; }
197 };
199 class instanceKlassHandle : public KlassHandle {
200 public:
201 /* Constructors */
202 instanceKlassHandle () : KlassHandle() {}
203 instanceKlassHandle (const Klass* k) : KlassHandle(k) {
204 assert(SharedSkipVerify || k == NULL || k->oop_is_instance(),
205 "illegal type");
206 }
207 instanceKlassHandle (Thread* thread, const Klass* k) : KlassHandle(thread, k) {
208 assert(SharedSkipVerify || k == NULL || k->oop_is_instance(),
209 "illegal type");
210 }
211 /* Access to klass part */
212 InstanceKlass* operator () () const { return (InstanceKlass*)obj(); }
213 InstanceKlass* operator -> () const { return (InstanceKlass*)obj(); }
214 };
217 //------------------------------------------------------------------------------------------------------------------------
218 // Thread local handle area
219 class HandleArea: public Arena {
220 friend class HandleMark;
221 friend class NoHandleMark;
222 friend class ResetNoHandleMark;
223 #ifdef ASSERT
224 int _handle_mark_nesting;
225 int _no_handle_mark_nesting;
226 #endif
227 HandleArea* _prev; // link to outer (older) area
228 public:
229 // Constructor
230 HandleArea(HandleArea* prev) {
231 debug_only(_handle_mark_nesting = 0);
232 debug_only(_no_handle_mark_nesting = 0);
233 _prev = prev;
234 }
236 // Handle allocation
237 private:
238 oop* real_allocate_handle(oop obj) {
239 #ifdef ASSERT
240 oop* handle = (oop*) (UseMallocOnly ? internal_malloc_4(oopSize) : Amalloc_4(oopSize));
241 #else
242 oop* handle = (oop*) Amalloc_4(oopSize);
243 #endif
244 *handle = obj;
245 return handle;
246 }
247 public:
248 #ifdef ASSERT
249 oop* allocate_handle(oop obj);
250 #else
251 oop* allocate_handle(oop obj) { return real_allocate_handle(obj); }
252 #endif
254 // Garbage collection support
255 void oops_do(OopClosure* f);
257 // Number of handles in use
258 size_t used() const { return Arena::used() / oopSize; }
260 debug_only(bool no_handle_mark_active() { return _no_handle_mark_nesting > 0; })
261 };
264 //------------------------------------------------------------------------------------------------------------------------
265 // Handles are allocated in a (growable) thread local handle area. Deallocation
266 // is managed using a HandleMark. It should normally not be necessary to use
267 // HandleMarks manually.
268 //
269 // A HandleMark constructor will record the current handle area top, and the
270 // desctructor will reset the top, destroying all handles allocated in between.
271 // The following code will therefore NOT work:
272 //
273 // Handle h;
274 // {
275 // HandleMark hm;
276 // h = Handle(obj);
277 // }
278 // h()->print(); // WRONG, h destroyed by HandleMark destructor.
279 //
280 // If h has to be preserved, it can be converted to an oop or a local JNI handle
281 // across the HandleMark boundary.
283 // The base class of HandleMark should have been StackObj but we also heap allocate
284 // a HandleMark when a thread is created.
286 class HandleMark {
287 private:
288 Thread *_thread; // thread that owns this mark
289 HandleArea *_area; // saved handle area
290 Chunk *_chunk; // saved arena chunk
291 char *_hwm, *_max; // saved arena info
292 size_t _size_in_bytes; // size of handle area
293 // Link to previous active HandleMark in thread
294 HandleMark* _previous_handle_mark;
296 void initialize(Thread* thread); // common code for constructors
297 void set_previous_handle_mark(HandleMark* mark) { _previous_handle_mark = mark; }
298 HandleMark* previous_handle_mark() const { return _previous_handle_mark; }
300 public:
301 HandleMark(); // see handles_inline.hpp
302 HandleMark(Thread* thread) { initialize(thread); }
303 ~HandleMark();
305 // Functions used by HandleMarkCleaner
306 // called in the constructor of HandleMarkCleaner
307 void push();
308 // called in the destructor of HandleMarkCleaner
309 void pop_and_restore();
310 };
312 //------------------------------------------------------------------------------------------------------------------------
313 // A NoHandleMark stack object will verify that no handles are allocated
314 // in its scope. Enabled in debug mode only.
316 class NoHandleMark: public StackObj {
317 public:
318 #ifdef ASSERT
319 NoHandleMark();
320 ~NoHandleMark();
321 #else
322 NoHandleMark() {}
323 ~NoHandleMark() {}
324 #endif
325 };
328 class ResetNoHandleMark: public StackObj {
329 int _no_handle_mark_nesting;
330 public:
331 #ifdef ASSERT
332 ResetNoHandleMark();
333 ~ResetNoHandleMark();
334 #else
335 ResetNoHandleMark() {}
336 ~ResetNoHandleMark() {}
337 #endif
338 };
340 #endif // SHARE_VM_RUNTIME_HANDLES_HPP