1 /*
2 * Copyright (c) 2003, 2006, 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 # include "incls/_precompiled.incl"
26 # include "incls/_loaderConstraints.cpp.incl"
27
28 LoaderConstraintTable::LoaderConstraintTable(int nof_buckets)
29 : Hashtable(nof_buckets, sizeof(LoaderConstraintEntry)) {};
30
31
32 LoaderConstraintEntry* LoaderConstraintTable::new_entry(
33 unsigned int hash, symbolOop name,
34 klassOop klass, int num_loaders,
35 int max_loaders) {
36 LoaderConstraintEntry* entry;
37 entry = (LoaderConstraintEntry*)Hashtable::new_entry(hash, klass);
38 entry->set_name(name);
39 entry->set_num_loaders(num_loaders);
40 entry->set_max_loaders(max_loaders);
41 return entry;
42 }
43
44
45 void LoaderConstraintTable::oops_do(OopClosure* f) {
46 for (int index = 0; index < table_size(); index++) {
47 for (LoaderConstraintEntry* probe = bucket(index);
48 probe != NULL;
49 probe = probe->next()) {
50 f->do_oop((oop*)(probe->name_addr()));
51 if (probe->klass() != NULL) {
52 f->do_oop((oop*)probe->klass_addr());
53 }
54 for (int n = 0; n < probe->num_loaders(); n++) {
55 if (probe->loader(n) != NULL) {
56 f->do_oop(probe->loader_addr(n));
57 }
58 }
59 }
60 }
61 }
62
63 // We must keep the symbolOop used in the name alive. We'll use the
64 // loaders to decide if a particular entry can be purged.
65 void LoaderConstraintTable::always_strong_classes_do(OopClosure* blk) {
66 // We must keep the symbolOop used in the name alive.
67 for (int cindex = 0; cindex < table_size(); cindex++) {
68 for (LoaderConstraintEntry* lc_probe = bucket(cindex);
69 lc_probe != NULL;
70 lc_probe = lc_probe->next()) {
71 assert (lc_probe->name() != NULL, "corrupted loader constraint table");
72 blk->do_oop((oop*)lc_probe->name_addr());
73 }
74 }
75 }
76
77
78 // The loaderConstraintTable must always be accessed with the
79 // SystemDictionary lock held. This is true even for readers as
80 // entries in the table could be being dynamically resized.
81
82 LoaderConstraintEntry** LoaderConstraintTable::find_loader_constraint(
83 symbolHandle name, Handle loader) {
84
85 unsigned int hash = compute_hash(name);
86 int index = hash_to_index(hash);
87 LoaderConstraintEntry** pp = bucket_addr(index);
88 while (*pp) {
89 LoaderConstraintEntry* p = *pp;
90 if (p->hash() == hash) {
91 if (p->name() == name()) {
92 for (int i = p->num_loaders() - 1; i >= 0; i--) {
93 if (p->loader(i) == loader()) {
94 return pp;
95 }
96 }
97 }
98 }
99 pp = p->next_addr();
100 }
101 return pp;
102 }
103
104
105 void LoaderConstraintTable::purge_loader_constraints(BoolObjectClosure* is_alive) {
106 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
107 // Remove unloaded entries from constraint table
108 for (int index = 0; index < table_size(); index++) {
109 LoaderConstraintEntry** p = bucket_addr(index);
110 while(*p) {
111 LoaderConstraintEntry* probe = *p;
112 klassOop klass = probe->klass();
113 // Remove klass that is no longer alive
114 if (klass != NULL && !is_alive->do_object_b(klass)) {
115 probe->set_klass(NULL);
116 if (TraceLoaderConstraints) {
117 ResourceMark rm;
118 tty->print_cr("[Purging class object from constraint for name %s,"
119 " loader list:",
120 probe->name()->as_C_string());
121 for (int i = 0; i < probe->num_loaders(); i++) {
122 tty->print_cr("[ [%d]: %s", i,
123 SystemDictionary::loader_name(probe->loader(i)));
124 }
125 }
126 }
127 // Remove entries no longer alive from loader array
128 int n = 0;
129 while (n < probe->num_loaders()) {
130 if (probe->loader(n) != NULL) {
131 if (!is_alive->do_object_b(probe->loader(n))) {
132 if (TraceLoaderConstraints) {
133 ResourceMark rm;
134 tty->print_cr("[Purging loader %s from constraint for name %s",
135 SystemDictionary::loader_name(probe->loader(n)),
136 probe->name()->as_C_string()
137 );
138 }
139
140 // Compact array
141 int num = probe->num_loaders() - 1;
142 probe->set_num_loaders(num);
143 probe->set_loader(n, probe->loader(num));
144 probe->set_loader(num, NULL);
145
146 if (TraceLoaderConstraints) {
147 ResourceMark rm;
148 tty->print_cr("[New loader list:");
149 for (int i = 0; i < probe->num_loaders(); i++) {
150 tty->print_cr("[ [%d]: %s", i,
151 SystemDictionary::loader_name(probe->loader(i)));
152 }
153 }
154
155 continue; // current element replaced, so restart without
156 // incrementing n
157 }
158 }
159 n++;
160 }
161 // Check whether entry should be purged
162 if (probe->num_loaders() < 2) {
163 if (TraceLoaderConstraints) {
164 ResourceMark rm;
165 tty->print("[Purging complete constraint for name %s\n",
166 probe->name()->as_C_string());
167 }
168
169 // Purge entry
170 *p = probe->next();
171 FREE_C_HEAP_ARRAY(oop, probe->loaders());
172 free_entry(probe);
173 } else {
174 #ifdef ASSERT
175 assert(is_alive->do_object_b(probe->name()), "name should be live");
176 if (probe->klass() != NULL) {
177 assert(is_alive->do_object_b(probe->klass()), "klass should be live");
178 }
179 for (n = 0; n < probe->num_loaders(); n++) {
180 if (probe->loader(n) != NULL) {
181 assert(is_alive->do_object_b(probe->loader(n)), "loader should be live");
182 }
183 }
184 #endif
185 // Go to next entry
186 p = probe->next_addr();
187 }
188 }
189 }
190 }
191
192 bool LoaderConstraintTable::add_entry(symbolHandle class_name,
193 klassOop klass1, Handle class_loader1,
194 klassOop klass2, Handle class_loader2) {
195 int failure_code = 0; // encode different reasons for failing
196
197 if (klass1 != NULL && klass2 != NULL && klass1 != klass2) {
198 failure_code = 1;
199 } else {
200 klassOop klass = klass1 != NULL ? klass1 : klass2;
201
202 LoaderConstraintEntry** pp1 = find_loader_constraint(class_name,
203 class_loader1);
204 if (*pp1 != NULL && (*pp1)->klass() != NULL) {
205 if (klass != NULL) {
206 if (klass != (*pp1)->klass()) {
207 failure_code = 2;
208 }
209 } else {
210 klass = (*pp1)->klass();
211 }
212 }
213
214 LoaderConstraintEntry** pp2 = find_loader_constraint(class_name,
215 class_loader2);
216 if (*pp2 != NULL && (*pp2)->klass() != NULL) {
217 if (klass != NULL) {
218 if (klass != (*pp2)->klass()) {
219 failure_code = 3;
220 }
221 } else {
222 klass = (*pp2)->klass();
223 }
224 }
225
226 if (failure_code == 0) {
227 if (*pp1 == NULL && *pp2 == NULL) {
228 unsigned int hash = compute_hash(class_name);
229 int index = hash_to_index(hash);
230 LoaderConstraintEntry* p;
231 p = new_entry(hash, class_name(), klass, 2, 2);
232 p->set_loaders(NEW_C_HEAP_ARRAY(oop, 2));
233 p->set_loader(0, class_loader1());
234 p->set_loader(1, class_loader2());
235 p->set_klass(klass);
236 p->set_next(bucket(index));
237 set_entry(index, p);
238 if (TraceLoaderConstraints) {
239 ResourceMark rm;
240 tty->print("[Adding new constraint for name: %s, loader[0]: %s,"
241 " loader[1]: %s ]\n",
242 class_name()->as_C_string(),
243 SystemDictionary::loader_name(class_loader1()),
244 SystemDictionary::loader_name(class_loader2())
245 );
246 }
247 } else if (*pp1 == *pp2) {
248 /* constraint already imposed */
249 if ((*pp1)->klass() == NULL) {
250 (*pp1)->set_klass(klass);
251 if (TraceLoaderConstraints) {
252 ResourceMark rm;
253 tty->print("[Setting class object in existing constraint for"
254 " name: %s and loader %s ]\n",
255 class_name()->as_C_string(),
256 SystemDictionary::loader_name(class_loader1())
257 );
258 }
259 } else {
260 assert((*pp1)->klass() == klass, "loader constraints corrupted");
261 }
262 } else if (*pp1 == NULL) {
263 extend_loader_constraint(*pp2, class_loader1, klass);
264 } else if (*pp2 == NULL) {
265 extend_loader_constraint(*pp1, class_loader2, klass);
266 } else {
267 merge_loader_constraints(pp1, pp2, klass);
268 }
269 }
270 }
271
272 if (failure_code != 0 && TraceLoaderConstraints) {
273 ResourceMark rm;
274 const char* reason = "";
275 switch(failure_code) {
276 case 1: reason = "the class objects presented by loader[0] and loader[1]"
277 " are different"; break;
278 case 2: reason = "the class object presented by loader[0] does not match"
279 " the stored class object in the constraint"; break;
280 case 3: reason = "the class object presented by loader[1] does not match"
281 " the stored class object in the constraint"; break;
282 default: reason = "unknown reason code";
283 }
284 tty->print("[Failed to add constraint for name: %s, loader[0]: %s,"
285 " loader[1]: %s, Reason: %s ]\n",
286 class_name()->as_C_string(),
287 SystemDictionary::loader_name(class_loader1()),
288 SystemDictionary::loader_name(class_loader2()),
289 reason
290 );
291 }
292
293 return failure_code == 0;
294 }
295
296
297 // return true if the constraint was updated, false if the constraint is
298 // violated
299 bool LoaderConstraintTable::check_or_update(instanceKlassHandle k,
300 Handle loader,
301 symbolHandle name) {
302 LoaderConstraintEntry* p = *(find_loader_constraint(name, loader));
303 if (p && p->klass() != NULL && p->klass() != k()) {
304 if (TraceLoaderConstraints) {
305 ResourceMark rm;
306 tty->print("[Constraint check failed for name %s, loader %s: "
307 "the presented class object differs from that stored ]\n",
308 name()->as_C_string(),
309 SystemDictionary::loader_name(loader()));
310 }
311 return false;
312 } else {
313 if (p && p->klass() == NULL) {
314 p->set_klass(k());
315 if (TraceLoaderConstraints) {
316 ResourceMark rm;
317 tty->print("[Updating constraint for name %s, loader %s, "
318 "by setting class object ]\n",
319 name()->as_C_string(),
320 SystemDictionary::loader_name(loader()));
321 }
322 }
323 return true;
324 }
325 }
326
327 klassOop LoaderConstraintTable::find_constrained_klass(symbolHandle name,
328 Handle loader) {
329 LoaderConstraintEntry *p = *(find_loader_constraint(name, loader));
330 if (p != NULL && p->klass() != NULL)
331 return p->klass();
332
333 // No constraints, or else no klass loaded yet.
334 return NULL;
335 }
336
337 void LoaderConstraintTable::ensure_loader_constraint_capacity(
338 LoaderConstraintEntry *p,
339 int nfree) {
340 if (p->max_loaders() - p->num_loaders() < nfree) {
341 int n = nfree + p->num_loaders();
342 oop* new_loaders = NEW_C_HEAP_ARRAY(oop, n);
343 memcpy(new_loaders, p->loaders(), sizeof(oop) * p->num_loaders());
344 p->set_max_loaders(n);
345 FREE_C_HEAP_ARRAY(oop, p->loaders());
346 p->set_loaders(new_loaders);
347 }
348 }
349
350
351 void LoaderConstraintTable::extend_loader_constraint(LoaderConstraintEntry* p,
352 Handle loader,
353 klassOop klass) {
354 ensure_loader_constraint_capacity(p, 1);
355 int num = p->num_loaders();
356 p->set_loader(num, loader());
357 p->set_num_loaders(num + 1);
358 if (TraceLoaderConstraints) {
359 ResourceMark rm;
360 tty->print("[Extending constraint for name %s by adding loader[%d]: %s %s",
361 p->name()->as_C_string(),
362 num,
363 SystemDictionary::loader_name(loader()),
364 (p->klass() == NULL ? " and setting class object ]\n" : " ]\n")
365 );
366 }
367 if (p->klass() == NULL) {
368 p->set_klass(klass);
369 } else {
370 assert(klass == NULL || p->klass() == klass, "constraints corrupted");
371 }
372 }
373
374
375 void LoaderConstraintTable::merge_loader_constraints(
376 LoaderConstraintEntry** pp1,
377 LoaderConstraintEntry** pp2,
378 klassOop klass) {
379 // make sure *pp1 has higher capacity
380 if ((*pp1)->max_loaders() < (*pp2)->max_loaders()) {
381 LoaderConstraintEntry** tmp = pp2;
382 pp2 = pp1;
383 pp1 = tmp;
384 }
385
386 LoaderConstraintEntry* p1 = *pp1;
387 LoaderConstraintEntry* p2 = *pp2;
388
389 ensure_loader_constraint_capacity(p1, p2->num_loaders());
390
391 for (int i = 0; i < p2->num_loaders(); i++) {
392 int num = p1->num_loaders();
393 p1->set_loader(num, p2->loader(i));
394 p1->set_num_loaders(num + 1);
395 }
396
397 if (TraceLoaderConstraints) {
398 ResourceMark rm;
399 tty->print_cr("[Merged constraints for name %s, new loader list:",
400 p1->name()->as_C_string()
401 );
402
403 for (int i = 0; i < p1->num_loaders(); i++) {
404 tty->print_cr("[ [%d]: %s", i,
405 SystemDictionary::loader_name(p1->loader(i)));
406 }
407 if (p1->klass() == NULL) {
408 tty->print_cr("[... and setting class object]");
409 }
410 }
411
412 // p1->klass() will hold NULL if klass, p2->klass(), and old
413 // p1->klass() are all NULL. In addition, all three must have
414 // matching non-NULL values, otherwise either the constraints would
415 // have been violated, or the constraints had been corrupted (and an
416 // assertion would fail).
417 if (p2->klass() != NULL) {
418 assert(p2->klass() == klass, "constraints corrupted");
419 }
420 if (p1->klass() == NULL) {
421 p1->set_klass(klass);
422 } else {
423 assert(p1->klass() == klass, "constraints corrupted");
424 }
425
426 *pp2 = p2->next();
427 FREE_C_HEAP_ARRAY(oop, p2->loaders());
428 free_entry(p2);
429 return;
430 }
431
432
433 void LoaderConstraintTable::verify(Dictionary* dictionary,
434 PlaceholderTable* placeholders) {
435 Thread *thread = Thread::current();
436 for (int cindex = 0; cindex < _loader_constraint_size; cindex++) {
437 for (LoaderConstraintEntry* probe = bucket(cindex);
438 probe != NULL;
439 probe = probe->next()) {
440 guarantee(probe->name()->is_symbol(), "should be symbol");
441 if (probe->klass() != NULL) {
442 instanceKlass* ik = instanceKlass::cast(probe->klass());
443 guarantee(ik->name() == probe->name(), "name should match");
444 symbolHandle name (thread, 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);
460
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 }
473
474 #ifndef PRODUCT
475
476 // Called with the system dictionary lock held
477 void LoaderConstraintTable::print() {
478 ResourceMark rm;
479
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