Mon, 24 Dec 2012 11:46:38 -0800
Merge
1 /*
2 * Copyright (c) 2003, 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_CLASSFILE_PLACEHOLDERS_HPP
26 #define SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP
28 #include "runtime/thread.hpp"
29 #include "utilities/hashtable.hpp"
31 class PlaceholderEntry;
33 // Placeholder objects. These represent classes currently
34 // being loaded, as well as arrays of primitives.
35 //
37 class PlaceholderTable : public TwoOopHashtable<Symbol*, mtClass> {
38 friend class VMStructs;
40 public:
41 PlaceholderTable(int table_size);
43 PlaceholderEntry* new_entry(int hash, Symbol* name, ClassLoaderData* loader_data, bool havesupername, Symbol* supername);
44 void free_entry(PlaceholderEntry* entry);
46 PlaceholderEntry* bucket(int i) {
47 return (PlaceholderEntry*)Hashtable<Symbol*, mtClass>::bucket(i);
48 }
50 PlaceholderEntry** bucket_addr(int i) {
51 return (PlaceholderEntry**)Hashtable<Symbol*, mtClass>::bucket_addr(i);
52 }
54 void add_entry(int index, PlaceholderEntry* new_entry) {
55 Hashtable<Symbol*, mtClass>::add_entry(index, (HashtableEntry<Symbol*, mtClass>*)new_entry);
56 }
58 void add_entry(int index, unsigned int hash, Symbol* name,
59 ClassLoaderData* loader_data, bool havesupername, Symbol* supername);
61 // This returns a Symbol* to match type for SystemDictionary
62 Symbol* find_entry(int index, unsigned int hash,
63 Symbol* name, ClassLoaderData* loader_data);
65 PlaceholderEntry* get_entry(int index, unsigned int hash,
66 Symbol* name, ClassLoaderData* loader_data);
68 // caller to create a placeholder entry must enumerate an action
69 // caller claims ownership of that action
70 // For parallel classloading:
71 // multiple LOAD_INSTANCE threads can proceed in parallel
72 // multiple LOAD_SUPER threads can proceed in parallel
73 // LOAD_SUPER needed to check for class circularity
74 // DEFINE_CLASS: ultimately define class must be single threaded
75 // on a class/classloader basis
76 // so the head of that queue owns the token
77 // and the rest of the threads return the result the first thread gets
78 enum classloadAction {
79 LOAD_INSTANCE = 1, // calling load_instance_class
80 LOAD_SUPER = 2, // loading superclass for this class
81 DEFINE_CLASS = 3 // find_or_define class
82 };
84 // find_and_add returns probe pointer - old or new
85 // If no entry exists, add a placeholder entry and push SeenThread
86 // If entry exists, reuse entry and push SeenThread for classloadAction
87 PlaceholderEntry* find_and_add(int index, unsigned int hash,
88 Symbol* name, ClassLoaderData* loader_data,
89 classloadAction action, Symbol* supername,
90 Thread* thread);
92 void remove_entry(int index, unsigned int hash,
93 Symbol* name, ClassLoaderData* loader_data);
95 // Remove placeholder information
96 void find_and_remove(int index, unsigned int hash,
97 Symbol* name, ClassLoaderData* loader_data, Thread* thread);
99 // GC support.
100 void classes_do(KlassClosure* f);
102 // JVMTI support
103 void entries_do(void f(Symbol*));
105 #ifndef PRODUCT
106 void print();
107 #endif
108 void verify();
109 };
111 // SeenThread objects represent list of threads that are
112 // currently performing a load action on a class.
113 // For class circularity, set before loading a superclass.
114 // For bootclasssearchpath, set before calling load_instance_class.
115 // Defining must be single threaded on a class/classloader basis
116 // For DEFINE_CLASS, the head of the queue owns the
117 // define token and the rest of the threads wait to return the
118 // result the first thread gets.
119 class SeenThread: public CHeapObj<mtInternal> {
120 private:
121 Thread *_thread;
122 SeenThread* _stnext;
123 SeenThread* _stprev;
124 public:
125 SeenThread(Thread *thread) {
126 _thread = thread;
127 _stnext = NULL;
128 _stprev = NULL;
129 }
130 Thread* thread() const { return _thread;}
131 void set_thread(Thread *thread) { _thread = thread; }
133 SeenThread* next() const { return _stnext;}
134 void set_next(SeenThread *seen) { _stnext = seen; }
135 void set_prev(SeenThread *seen) { _stprev = seen; }
137 #ifndef PRODUCT
138 void printActionQ() {
139 SeenThread* seen = this;
140 while (seen != NULL) {
141 seen->thread()->print_value();
142 tty->print(", ");
143 seen = seen->next();
144 }
145 }
146 #endif // PRODUCT
147 };
149 // Placeholder objects represent classes currently being loaded.
150 // All threads examining the placeholder table must hold the
151 // SystemDictionary_lock, so we don't need special precautions
152 // on store ordering here.
153 // The system dictionary is the only user of this class.
155 class PlaceholderEntry : public HashtableEntry<Symbol*, mtClass> {
156 friend class VMStructs;
159 private:
160 ClassLoaderData* _loader_data; // initiating loader
161 bool _havesupername; // distinguish between null supername, and unknown
162 Symbol* _supername;
163 Thread* _definer; // owner of define token
164 Klass* _instanceKlass; // InstanceKlass from successful define
165 SeenThread* _superThreadQ; // doubly-linked queue of Threads loading a superclass for this class
166 SeenThread* _loadInstanceThreadQ; // loadInstance thread
167 // can be multiple threads if classloader object lock broken by application
168 // or if classloader supports parallel classloading
170 SeenThread* _defineThreadQ; // queue of Threads trying to define this class
171 // including _definer
172 // _definer owns token
173 // queue waits for and returns results from _definer
175 public:
176 // Simple accessors, used only by SystemDictionary
177 Symbol* klassname() const { return literal(); }
179 ClassLoaderData* loader_data() const { return _loader_data; }
180 void set_loader_data(ClassLoaderData* loader_data) { _loader_data = loader_data; }
182 bool havesupername() const { return _havesupername; }
183 void set_havesupername(bool havesupername) { _havesupername = havesupername; }
185 Symbol* supername() const { return _supername; }
186 void set_supername(Symbol* supername) {
187 _supername = supername;
188 if (_supername != NULL) _supername->increment_refcount();
189 }
191 Thread* definer() const {return _definer; }
192 void set_definer(Thread* definer) { _definer = definer; }
194 Klass* instance_klass() const {return _instanceKlass; }
195 void set_instance_klass(Klass* ik) { _instanceKlass = ik; }
197 SeenThread* superThreadQ() const { return _superThreadQ; }
198 void set_superThreadQ(SeenThread* SeenThread) { _superThreadQ = SeenThread; }
200 SeenThread* loadInstanceThreadQ() const { return _loadInstanceThreadQ; }
201 void set_loadInstanceThreadQ(SeenThread* SeenThread) { _loadInstanceThreadQ = SeenThread; }
203 SeenThread* defineThreadQ() const { return _defineThreadQ; }
204 void set_defineThreadQ(SeenThread* SeenThread) { _defineThreadQ = SeenThread; }
206 PlaceholderEntry* next() const {
207 return (PlaceholderEntry*)HashtableEntry<Symbol*, mtClass>::next();
208 }
210 PlaceholderEntry** next_addr() {
211 return (PlaceholderEntry**)HashtableEntry<Symbol*, mtClass>::next_addr();
212 }
214 // Test for equality
215 // Entries are unique for class/classloader name pair
216 bool equals(Symbol* class_name, ClassLoaderData* loader) const {
217 return (klassname() == class_name && loader_data() == loader);
218 }
220 SeenThread* actionToQueue(PlaceholderTable::classloadAction action) {
221 SeenThread* queuehead;
222 switch (action) {
223 case PlaceholderTable::LOAD_INSTANCE:
224 queuehead = _loadInstanceThreadQ;
225 break;
226 case PlaceholderTable::LOAD_SUPER:
227 queuehead = _superThreadQ;
228 break;
229 case PlaceholderTable::DEFINE_CLASS:
230 queuehead = _defineThreadQ;
231 break;
232 default: Unimplemented();
233 }
234 return queuehead;
235 }
237 void set_threadQ(SeenThread* seenthread, PlaceholderTable::classloadAction action) {
238 switch (action) {
239 case PlaceholderTable::LOAD_INSTANCE:
240 _loadInstanceThreadQ = seenthread;
241 break;
242 case PlaceholderTable::LOAD_SUPER:
243 _superThreadQ = seenthread;
244 break;
245 case PlaceholderTable::DEFINE_CLASS:
246 _defineThreadQ = seenthread;
247 break;
248 default: Unimplemented();
249 }
250 return;
251 }
253 bool super_load_in_progress() {
254 return (_superThreadQ != NULL);
255 }
257 bool instance_load_in_progress() {
258 return (_loadInstanceThreadQ != NULL);
259 }
261 bool define_class_in_progress() {
262 return (_defineThreadQ != NULL);
263 }
265 // Doubly-linked list of Threads per action for class/classloader pair
266 // Class circularity support: links in thread before loading superclass
267 // bootstrapsearchpath support: links in a thread before load_instance_class
268 // definers: use as queue of define requestors, including owner of
269 // define token. Appends for debugging of requestor order
270 void add_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
271 assert_lock_strong(SystemDictionary_lock);
272 SeenThread* threadEntry = new SeenThread(thread);
273 SeenThread* seen = actionToQueue(action);
275 if (seen == NULL) {
276 set_threadQ(threadEntry, action);
277 return;
278 }
279 SeenThread* next;
280 while ((next = seen->next()) != NULL) {
281 seen = next;
282 }
283 seen->set_next(threadEntry);
284 threadEntry->set_prev(seen);
285 return;
286 }
288 bool check_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
289 assert_lock_strong(SystemDictionary_lock);
290 SeenThread* threadQ = actionToQueue(action);
291 SeenThread* seen = threadQ;
292 while (seen) {
293 if (thread == seen->thread()) {
294 return true;
295 }
296 seen = seen->next();
297 }
298 return false;
299 }
301 // returns true if seenthreadQ is now empty
302 // Note, caller must ensure probe still exists while holding
303 // SystemDictionary_lock
304 // ignores if cleanup has already been done
305 // if found, deletes SeenThread
306 bool remove_seen_thread(Thread* thread, PlaceholderTable::classloadAction action) {
307 assert_lock_strong(SystemDictionary_lock);
308 SeenThread* threadQ = actionToQueue(action);
309 SeenThread* seen = threadQ;
310 SeenThread* prev = NULL;
311 while (seen) {
312 if (thread == seen->thread()) {
313 if (prev) {
314 prev->set_next(seen->next());
315 } else {
316 set_threadQ(seen->next(), action);
317 }
318 if (seen->next()) {
319 seen->next()->set_prev(prev);
320 }
321 delete seen;
322 break;
323 }
324 prev = seen;
325 seen = seen->next();
326 }
327 return (actionToQueue(action) == NULL);
328 }
330 // GC support
331 // Applies "f->do_oop" to all root oops in the placeholder table.
332 void classes_do(KlassClosure* closure);
334 // Print method doesn't append a cr
335 void print() const PRODUCT_RETURN;
336 void verify() const;
337 };
339 #endif // SHARE_VM_CLASSFILE_PLACEHOLDERS_HPP