Mercurial > jdk8-mips64-public > hotspot / file revision
src/share/vm/classfile/loaderConstraints.cpp@b099aaf51bf8
src/share/vm/classfile/loaderConstraints.cpp
Tue, 22 Mar 2011 13:36:33 -0700
- author
- jcoomes
- date
- Tue, 22 Mar 2011 13:36:33 -0700
- changeset 2661
- b099aaf51bf8
- parent 2551
- 4f26f535a225
- child 2708
- 1d1603768966
- permissions
- -rw-r--r--
6962931: move interned strings out of the perm gen
Reviewed-by: never, coleenp, ysr, jwilhelm
1 /*
2 * Copyright (c) 2003, 2010, 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 #include "precompiled.hpp"
26 #include "classfile/loaderConstraints.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "oops/oop.inline.hpp"
29 #include "runtime/handles.inline.hpp"
30 #include "runtime/safepoint.hpp"
31 #include "utilities/hashtable.inline.hpp"
33 LoaderConstraintTable::LoaderConstraintTable(int nof_buckets)
34 : Hashtable<klassOop>(nof_buckets, sizeof(LoaderConstraintEntry)) {};
37 LoaderConstraintEntry* LoaderConstraintTable::new_entry(
38 unsigned int hash, Symbol* name,
39 klassOop klass, int num_loaders,
40 int max_loaders) {
41 LoaderConstraintEntry* entry;
42 entry = (LoaderConstraintEntry*)Hashtable<klassOop>::new_entry(hash, klass);
43 entry->set_name(name);
44 entry->set_num_loaders(num_loaders);
45 entry->set_max_loaders(max_loaders);
46 return entry;
47 }
49 void LoaderConstraintTable::free_entry(LoaderConstraintEntry *entry) {
50 // decrement name refcount before freeing
51 entry->name()->decrement_refcount();
52 Hashtable<klassOop>::free_entry(entry);
53 }
56 void LoaderConstraintTable::oops_do(OopClosure* f) {
57 for (int index = 0; index < table_size(); index++) {
58 for (LoaderConstraintEntry* probe = bucket(index);
59 probe != NULL;
60 probe = probe->next()) {
61 if (probe->klass() != NULL) {
62 f->do_oop((oop*)probe->klass_addr());
63 }
64 for (int n = 0; n < probe->num_loaders(); n++) {
65 if (probe->loader(n) != NULL) {
66 f->do_oop(probe->loader_addr(n));
67 }
68 }
69 }
70 }
71 }
74 // The loaderConstraintTable must always be accessed with the
75 // SystemDictionary lock held. This is true even for readers as
76 // entries in the table could be being dynamically resized.
78 LoaderConstraintEntry** LoaderConstraintTable::find_loader_constraint(
79 Symbol* name, Handle loader) {
81 unsigned int hash = compute_hash(name);
82 int index = hash_to_index(hash);
83 LoaderConstraintEntry** pp = bucket_addr(index);
84 while (*pp) {
85 LoaderConstraintEntry* p = *pp;
86 if (p->hash() == hash) {
87 if (p->name() == name) {
88 for (int i = p->num_loaders() - 1; i >= 0; i--) {
89 if (p->loader(i) == loader()) {
90 return pp;
91 }
92 }
93 }
94 }
95 pp = p->next_addr();
96 }
97 return pp;
98 }
101 void LoaderConstraintTable::purge_loader_constraints(BoolObjectClosure* is_alive) {
102 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
103 // Remove unloaded entries from constraint table
104 for (int index = 0; index < table_size(); index++) {
105 LoaderConstraintEntry** p = bucket_addr(index);
106 while(*p) {
107 LoaderConstraintEntry* probe = *p;
108 klassOop klass = probe->klass();
109 // Remove klass that is no longer alive
110 if (klass != NULL && !is_alive->do_object_b(klass)) {
111 probe->set_klass(NULL);
112 if (TraceLoaderConstraints) {
113 ResourceMark rm;
114 tty->print_cr("[Purging class object from constraint for name %s,"
115 " loader list:",
116 probe->name()->as_C_string());
117 for (int i = 0; i < probe->num_loaders(); i++) {
118 tty->print_cr("[ [%d]: %s", i,
119 SystemDictionary::loader_name(probe->loader(i)));
120 }
121 }
122 }
123 // Remove entries no longer alive from loader array
124 int n = 0;
125 while (n < probe->num_loaders()) {
126 if (probe->loader(n) != NULL) {
127 if (!is_alive->do_object_b(probe->loader(n))) {
128 if (TraceLoaderConstraints) {
129 ResourceMark rm;
130 tty->print_cr("[Purging loader %s from constraint for name %s",
131 SystemDictionary::loader_name(probe->loader(n)),
132 probe->name()->as_C_string()
133 );
134 }
136 // Compact array
137 int num = probe->num_loaders() - 1;
138 probe->set_num_loaders(num);
139 probe->set_loader(n, probe->loader(num));
140 probe->set_loader(num, NULL);
142 if (TraceLoaderConstraints) {
143 ResourceMark rm;
144 tty->print_cr("[New loader list:");
145 for (int i = 0; i < probe->num_loaders(); i++) {
146 tty->print_cr("[ [%d]: %s", i,
147 SystemDictionary::loader_name(probe->loader(i)));
148 }
149 }
151 continue; // current element replaced, so restart without
152 // incrementing n
153 }
154 }
155 n++;
156 }
157 // Check whether entry should be purged
158 if (probe->num_loaders() < 2) {
159 if (TraceLoaderConstraints) {
160 ResourceMark rm;
161 tty->print("[Purging complete constraint for name %s\n",
162 probe->name()->as_C_string());
163 }
165 // Purge entry
166 *p = probe->next();
167 FREE_C_HEAP_ARRAY(oop, probe->loaders());
168 free_entry(probe);
169 } else {
170 #ifdef ASSERT
171 if (probe->klass() != NULL) {
172 assert(is_alive->do_object_b(probe->klass()), "klass should be live");
173 }
174 for (n = 0; n < probe->num_loaders(); n++) {
175 if (probe->loader(n) != NULL) {
176 assert(is_alive->do_object_b(probe->loader(n)), "loader should be live");
177 }
178 }
179 #endif
180 // Go to next entry
181 p = probe->next_addr();
182 }
183 }
184 }
185 }
187 bool LoaderConstraintTable::add_entry(Symbol* class_name,
188 klassOop klass1, Handle class_loader1,
189 klassOop klass2, Handle class_loader2) {
190 int failure_code = 0; // encode different reasons for failing
192 if (klass1 != NULL && klass2 != NULL && klass1 != klass2) {
193 failure_code = 1;
194 } else {
195 klassOop klass = klass1 != NULL ? klass1 : klass2;
197 LoaderConstraintEntry** pp1 = find_loader_constraint(class_name,
198 class_loader1);
199 if (*pp1 != NULL && (*pp1)->klass() != NULL) {
200 if (klass != NULL) {
201 if (klass != (*pp1)->klass()) {
202 failure_code = 2;
203 }
204 } else {
205 klass = (*pp1)->klass();
206 }
207 }
209 LoaderConstraintEntry** pp2 = find_loader_constraint(class_name,
210 class_loader2);
211 if (*pp2 != NULL && (*pp2)->klass() != NULL) {
212 if (klass != NULL) {
213 if (klass != (*pp2)->klass()) {
214 failure_code = 3;
215 }
216 } else {
217 klass = (*pp2)->klass();
218 }
219 }
221 if (failure_code == 0) {
222 if (*pp1 == NULL && *pp2 == NULL) {
223 unsigned int hash = compute_hash(class_name);
224 int index = hash_to_index(hash);
225 LoaderConstraintEntry* p;
226 p = new_entry(hash, class_name, klass, 2, 2);
227 p->set_loaders(NEW_C_HEAP_ARRAY(oop, 2));
228 p->set_loader(0, class_loader1());
229 p->set_loader(1, class_loader2());
230 p->set_klass(klass);
231 p->set_next(bucket(index));
232 set_entry(index, p);
233 if (TraceLoaderConstraints) {
234 ResourceMark rm;
235 tty->print("[Adding new constraint for name: %s, loader[0]: %s,"
236 " loader[1]: %s ]\n",
237 class_name->as_C_string(),
238 SystemDictionary::loader_name(class_loader1()),
239 SystemDictionary::loader_name(class_loader2())
240 );
241 }
242 } else if (*pp1 == *pp2) {
243 /* constraint already imposed */
244 if ((*pp1)->klass() == NULL) {
245 (*pp1)->set_klass(klass);
246 if (TraceLoaderConstraints) {
247 ResourceMark rm;
248 tty->print("[Setting class object in existing constraint for"
249 " name: %s and loader %s ]\n",
250 class_name->as_C_string(),
251 SystemDictionary::loader_name(class_loader1())
252 );
253 }
254 } else {
255 assert((*pp1)->klass() == klass, "loader constraints corrupted");
256 }
257 } else if (*pp1 == NULL) {
258 extend_loader_constraint(*pp2, class_loader1, klass);
259 } else if (*pp2 == NULL) {
260 extend_loader_constraint(*pp1, class_loader2, klass);
261 } else {
262 merge_loader_constraints(pp1, pp2, klass);
263 }
264 }
265 }
267 if (failure_code != 0 && TraceLoaderConstraints) {
268 ResourceMark rm;
269 const char* reason = "";
270 switch(failure_code) {
271 case 1: reason = "the class objects presented by loader[0] and loader[1]"
272 " are different"; break;
273 case 2: reason = "the class object presented by loader[0] does not match"
274 " the stored class object in the constraint"; break;
275 case 3: reason = "the class object presented by loader[1] does not match"
276 " the stored class object in the constraint"; break;
277 default: reason = "unknown reason code";
278 }
279 tty->print("[Failed to add constraint for name: %s, loader[0]: %s,"
280 " loader[1]: %s, Reason: %s ]\n",
281 class_name->as_C_string(),
282 SystemDictionary::loader_name(class_loader1()),
283 SystemDictionary::loader_name(class_loader2()),
284 reason
285 );
286 }
288 return failure_code == 0;
289 }
292 // return true if the constraint was updated, false if the constraint is
293 // violated
294 bool LoaderConstraintTable::check_or_update(instanceKlassHandle k,
295 Handle loader,
296 Symbol* name) {
297 LoaderConstraintEntry* p = *(find_loader_constraint(name, loader));
298 if (p && p->klass() != NULL && p->klass() != k()) {
299 if (TraceLoaderConstraints) {
300 ResourceMark rm;
301 tty->print("[Constraint check failed for name %s, loader %s: "
302 "the presented class object differs from that stored ]\n",
303 name->as_C_string(),
304 SystemDictionary::loader_name(loader()));
305 }
306 return false;
307 } else {
308 if (p && p->klass() == NULL) {
309 p->set_klass(k());
310 if (TraceLoaderConstraints) {
311 ResourceMark rm;
312 tty->print("[Updating constraint for name %s, loader %s, "
313 "by setting class object ]\n",
314 name->as_C_string(),
315 SystemDictionary::loader_name(loader()));
316 }
317 }
318 return true;
319 }
320 }
322 klassOop LoaderConstraintTable::find_constrained_klass(Symbol* name,
323 Handle loader) {
324 LoaderConstraintEntry *p = *(find_loader_constraint(name, loader));
325 if (p != NULL && p->klass() != NULL) {
326 if (Klass::cast(p->klass())->oop_is_instance() && !instanceKlass::cast(p->klass())->is_loaded()) {
327 // Only return fully loaded classes. Classes found through the
328 // constraints might still be in the process of loading.
329 return NULL;
330 }
331 return p->klass();
332 }
334 // No constraints, or else no klass loaded yet.
335 return NULL;
336 }
338 void LoaderConstraintTable::ensure_loader_constraint_capacity(
339 LoaderConstraintEntry *p,
340 int nfree) {
341 if (p->max_loaders() - p->num_loaders() < nfree) {
342 int n = nfree + p->num_loaders();
343 oop* new_loaders = NEW_C_HEAP_ARRAY(oop, n);
344 memcpy(new_loaders, p->loaders(), sizeof(oop) * p->num_loaders());
345 p->set_max_loaders(n);
346 FREE_C_HEAP_ARRAY(oop, p->loaders());
347 p->set_loaders(new_loaders);
348 }
349 }
352 void LoaderConstraintTable::extend_loader_constraint(LoaderConstraintEntry* p,
353 Handle loader,
354 klassOop klass) {
355 ensure_loader_constraint_capacity(p, 1);
356 int num = p->num_loaders();
357 p->set_loader(num, loader());
358 p->set_num_loaders(num + 1);
359 if (TraceLoaderConstraints) {
360 ResourceMark rm;
361 tty->print("[Extending constraint for name %s by adding loader[%d]: %s %s",
362 p->name()->as_C_string(),
363 num,
364 SystemDictionary::loader_name(loader()),
365 (p->klass() == NULL ? " and setting class object ]\n" : " ]\n")
366 );
367 }
368 if (p->klass() == NULL) {
369 p->set_klass(klass);
370 } else {
371 assert(klass == NULL || p->klass() == klass, "constraints corrupted");
372 }
373 }
376 void LoaderConstraintTable::merge_loader_constraints(
377 LoaderConstraintEntry** pp1,
378 LoaderConstraintEntry** pp2,
379 klassOop klass) {
380 // make sure *pp1 has higher capacity
381 if ((*pp1)->max_loaders() < (*pp2)->max_loaders()) {
382 LoaderConstraintEntry** tmp = pp2;
383 pp2 = pp1;
384 pp1 = tmp;
385 }
387 LoaderConstraintEntry* p1 = *pp1;
388 LoaderConstraintEntry* p2 = *pp2;
390 ensure_loader_constraint_capacity(p1, p2->num_loaders());
392 for (int i = 0; i < p2->num_loaders(); i++) {
393 int num = p1->num_loaders();
394 p1->set_loader(num, p2->loader(i));
395 p1->set_num_loaders(num + 1);
396 }
398 if (TraceLoaderConstraints) {
399 ResourceMark rm;
400 tty->print_cr("[Merged constraints for name %s, new loader list:",
401 p1->name()->as_C_string()
402 );
404 for (int i = 0; i < p1->num_loaders(); i++) {
405 tty->print_cr("[ [%d]: %s", i,
406 SystemDictionary::loader_name(p1->loader(i)));
407 }
408 if (p1->klass() == NULL) {
409 tty->print_cr("[... and setting class object]");
410 }
411 }
413 // p1->klass() will hold NULL if klass, p2->klass(), and old
414 // p1->klass() are all NULL. In addition, all three must have
415 // matching non-NULL values, otherwise either the constraints would
416 // have been violated, or the constraints had been corrupted (and an
417 // assertion would fail).
418 if (p2->klass() != NULL) {
419 assert(p2->klass() == klass, "constraints corrupted");
420 }
421 if (p1->klass() == NULL) {
422 p1->set_klass(klass);
423 } else {
424 assert(p1->klass() == klass, "constraints corrupted");
425 }
427 *pp2 = p2->next();
428 FREE_C_HEAP_ARRAY(oop, p2->loaders());
429 free_entry(p2);
430 return;
431 }
434 void LoaderConstraintTable::verify(Dictionary* dictionary,
435 PlaceholderTable* placeholders) {
436 Thread *thread = Thread::current();
437 for (int cindex = 0; cindex < _loader_constraint_size; cindex++) {
438 for (LoaderConstraintEntry* probe = bucket(cindex);
439 probe != NULL;
440 probe = probe->next()) {
441 if (probe->klass() != NULL) {
442 instanceKlass* ik = instanceKlass::cast(probe->klass());
443 guarantee(ik->name() == probe->name(), "name should match");
444 Symbol* name = ik->name();
445 Handle loader(thread, ik->class_loader());
446 unsigned int d_hash = dictionary->compute_hash(name, loader);
447 int d_index = dictionary->hash_to_index(d_hash);
448 klassOop k = dictionary->find_class(d_index, d_hash, name, loader);
449 if (k != NULL) {
450 // We found the class in the system dictionary, so we should
451 // make sure that the klassOop matches what we already have.
452 guarantee(k == probe->klass(), "klass should be in dictionary");
453 } else {
454 // If we don't find the class in the system dictionary, it
455 // has to be in the placeholders table.
456 unsigned int p_hash = placeholders->compute_hash(name, loader);
457 int p_index = placeholders->hash_to_index(p_hash);
458 PlaceholderEntry* entry = placeholders->get_entry(p_index, p_hash,
459 name, loader);
461 // The instanceKlass might not be on the entry, so the only
462 // thing we can check here is whether we were successful in
463 // finding the class in the placeholders table.
464 guarantee(entry != NULL, "klass should be in the placeholders");
465 }
466 }
467 for (int n = 0; n< probe->num_loaders(); n++) {
468 guarantee(probe->loader(n)->is_oop_or_null(), "should be oop");
469 }
470 }
471 }
472 }
474 #ifndef PRODUCT
476 // Called with the system dictionary lock held
477 void LoaderConstraintTable::print() {
478 ResourceMark rm;
480 assert_locked_or_safepoint(SystemDictionary_lock);
481 tty->print_cr("Java loader constraints (entries=%d)", _loader_constraint_size);
482 for (int cindex = 0; cindex < _loader_constraint_size; cindex++) {
483 for (LoaderConstraintEntry* probe = bucket(cindex);
484 probe != NULL;
485 probe = probe->next()) {
486 tty->print("%4d: ", cindex);
487 probe->name()->print();
488 tty->print(" , loaders:");
489 for (int n = 0; n < probe->num_loaders(); n++) {
490 probe->loader(n)->print_value();
491 tty->print(", ");
492 }
493 tty->cr();
494 }
495 }
496 }
497 #endif
