loaderConstraints.cpp revision 2273:1d1603768966
1/* 2 * Copyright (c) 2003, 2011, 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 "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" 32 33LoaderConstraintTable::LoaderConstraintTable(int nof_buckets) 34 : Hashtable<klassOop>(nof_buckets, sizeof(LoaderConstraintEntry)) {}; 35 36 37LoaderConstraintEntry* 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} 48 49void LoaderConstraintTable::free_entry(LoaderConstraintEntry *entry) { 50 // decrement name refcount before freeing 51 entry->name()->decrement_refcount(); 52 Hashtable<klassOop>::free_entry(entry); 53} 54 55 56void 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} 72 73 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. 77 78LoaderConstraintEntry** LoaderConstraintTable::find_loader_constraint( 79 Symbol* name, Handle loader) { 80 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} 99 100 101void 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 } 135 136 // 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); 141 142 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 } 150 151 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 } 164 165 // 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} 186 187bool 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 191 192 if (klass1 != NULL && klass2 != NULL && klass1 != klass2) { 193 failure_code = 1; 194 } else { 195 klassOop klass = klass1 != NULL ? klass1 : klass2; 196 197 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 } 208 209 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 } 220 221 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 } 266 267 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 } 287 288 return failure_code == 0; 289} 290 291 292// return true if the constraint was updated, false if the constraint is 293// violated 294bool 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} 321 322klassOop 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 } 333 334 // No constraints, or else no klass loaded yet. 335 return NULL; 336} 337 338void 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} 350 351 352void 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} 374 375 376void 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 } 386 387 LoaderConstraintEntry* p1 = *pp1; 388 LoaderConstraintEntry* p2 = *pp2; 389 390 ensure_loader_constraint_capacity(p1, p2->num_loaders()); 391 392 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 } 397 398 if (TraceLoaderConstraints) { 399 ResourceMark rm; 400 tty->print_cr("[Merged constraints for name %s, new loader list:", 401 p1->name()->as_C_string() 402 ); 403 404 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 } 412 413 // 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 } 426 427 *pp2 = p2->next(); 428 FREE_C_HEAP_ARRAY(oop, p2->loaders()); 429 free_entry(p2); 430 return; 431} 432 433 434void 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); 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 477void 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 498