1 /*
2 * Copyright (c) 2016, 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/classLoaderData.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "logging/log.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/symbol.hpp"
32 #include "prims/jni.h"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "trace/traceMacros.hpp"
36 #include "utilities/events.hpp"
37 #include "utilities/growableArray.hpp"
38 #include "utilities/hashtable.inline.hpp"
39 #include "utilities/ostream.hpp"
40
41 ModuleEntry* ModuleEntryTable::_javabase_module = NULL;
42
43 void ModuleEntry::set_location(Symbol* location) {
44 if (_location != NULL) {
45 // _location symbol's refcounts are managed by ModuleEntry,
46 // must decrement the old one before updating.
47 _location->decrement_refcount();
48 }
49
50 _location = location;
51
52 if (location != NULL) {
53 location->increment_refcount();
54 }
55 }
56
57 bool ModuleEntry::is_non_jdk_module() {
58 ResourceMark rm;
59 if (location() != NULL) {
60 const char* loc = location()->as_C_string();
61 if (strncmp(loc, "jrt:/java.", 10) != 0 && strncmp(loc, "jrt:/jdk.", 9) != 0) {
62 return true;
63 }
64 }
65 return false;
66 }
67
68 void ModuleEntry::set_version(Symbol* version) {
69 if (_version != NULL) {
70 // _version symbol's refcounts are managed by ModuleEntry,
71 // must decrement the old one before updating.
72 _version->decrement_refcount();
73 }
74
75 _version = version;
76
77 if (version != NULL) {
78 version->increment_refcount();
79 }
80 }
81
82 // Returns the shared ProtectionDomain
83 Handle ModuleEntry::shared_protection_domain() {
84 return Handle(JNIHandles::resolve(_pd));
85 }
86
87 // Set the shared ProtectionDomain atomically
88 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
89 Handle pd_h) {
90 // Create a JNI handle for the shared ProtectionDomain and save it atomically.
91 // If someone beats us setting the _pd cache, the created JNI handle is destroyed.
92 jobject obj = loader_data->add_handle(pd_h);
93 if (Atomic::cmpxchg_ptr(obj, &_pd, NULL) != NULL) {
94 loader_data->remove_handle(obj);
95 }
96 }
97
98 // Returns true if this module can read module m
99 bool ModuleEntry::can_read(ModuleEntry* m) const {
100 assert(m != NULL, "No module to lookup in this module's reads list");
101
102 // Unnamed modules read everyone and all modules
103 // read java.base. If either of these conditions
104 // hold, readability has been established.
105 if (!this->is_named() ||
106 (m == ModuleEntryTable::javabase_moduleEntry())) {
107 return true;
108 }
109
110 MutexLocker m1(Module_lock);
111 if (!has_reads()) {
112 return false;
113 } else {
114 return _reads->contains(m);
115 }
116 }
117
118 // Add a new module to this module's reads list
119 void ModuleEntry::add_read(ModuleEntry* m) {
120 MutexLocker m1(Module_lock);
121 if (m == NULL) {
122 set_can_read_all_unnamed();
123 } else {
124 if (_reads == NULL) {
125 // Lazily create a module's reads list
126 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
127 }
128
129 // Determine, based on this newly established read edge to module m,
130 // if this module's read list should be walked at a GC safepoint.
131 set_read_walk_required(m->loader_data());
132
133 // Establish readability to module m
134 _reads->append_if_missing(m);
135 }
136 }
137
138 // If the module's loader, that a read edge is being established to, is
139 // not the same loader as this module's and is not one of the 3 builtin
140 // class loaders, then this module's reads list must be walked at GC
141 // safepoint. Modules have the same life cycle as their defining class
142 // loaders and should be removed if dead.
143 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
144 assert_locked_or_safepoint(Module_lock);
145 if (!_must_walk_reads &&
146 loader_data() != m_loader_data &&
147 !m_loader_data->is_builtin_class_loader_data()) {
148 _must_walk_reads = true;
149 if (log_is_enabled(Trace, modules)) {
150 ResourceMark rm;
151 log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
152 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
153 }
154 }
155 }
156
157 bool ModuleEntry::has_reads() const {
158 assert_locked_or_safepoint(Module_lock);
159 return ((_reads != NULL) && !_reads->is_empty());
160 }
161
162 // Purge dead module entries out of reads list.
163 void ModuleEntry::purge_reads() {
164 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
165
166 if (_must_walk_reads && has_reads()) {
167 // This module's _must_walk_reads flag will be reset based
168 // on the remaining live modules on the reads list.
169 _must_walk_reads = false;
170
171 if (log_is_enabled(Trace, modules)) {
172 ResourceMark rm;
173 log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked",
174 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
175 }
176
177 // Go backwards because this removes entries that are dead.
178 int len = _reads->length();
179 for (int idx = len - 1; idx >= 0; idx--) {
180 ModuleEntry* module_idx = _reads->at(idx);
181 ClassLoaderData* cld_idx = module_idx->loader_data();
182 if (cld_idx->is_unloading()) {
183 _reads->delete_at(idx);
184 } else {
185 // Update the need to walk this module's reads based on live modules
186 set_read_walk_required(cld_idx);
187 }
188 }
189 }
190 }
191
192 void ModuleEntry::module_reads_do(ModuleClosure* const f) {
193 assert_locked_or_safepoint(Module_lock);
194 assert(f != NULL, "invariant");
195
196 if (has_reads()) {
197 int reads_len = _reads->length();
198 for (int i = 0; i < reads_len; ++i) {
199 f->do_module(_reads->at(i));
200 }
201 }
202 }
203
204 void ModuleEntry::delete_reads() {
205 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
206 delete _reads;
207 _reads = NULL;
208 }
209
210 ModuleEntryTable::ModuleEntryTable(int table_size)
211 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry)), _unnamed_module(NULL)
212 {
213 }
214
215 ModuleEntryTable::~ModuleEntryTable() {
216 assert_locked_or_safepoint(Module_lock);
217
218 // Walk through all buckets and all entries in each bucket,
219 // freeing each entry.
220 for (int i = 0; i < table_size(); ++i) {
221 for (ModuleEntry* m = bucket(i); m != NULL;) {
222 ModuleEntry* to_remove = m;
223 // read next before freeing.
224 m = m->next();
225
226 ResourceMark rm;
227 log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
228 to_remove->name()->as_C_string() : UNNAMED_MODULE);
229
230 // Clean out the C heap allocated reads list first before freeing the entry
231 to_remove->delete_reads();
232 if (to_remove->name() != NULL) {
233 to_remove->name()->decrement_refcount();
234 }
235 if (to_remove->version() != NULL) {
236 to_remove->version()->decrement_refcount();
237 }
238 if (to_remove->location() != NULL) {
239 to_remove->location()->decrement_refcount();
240 }
241
242 // Unlink from the Hashtable prior to freeing
243 unlink_entry(to_remove);
244 FREE_C_HEAP_ARRAY(char, to_remove);
245 }
246 }
247 assert(number_of_entries() == 0, "should have removed all entries");
248 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
249 free_buckets();
250 }
251
252 void ModuleEntryTable::create_unnamed_module(ClassLoaderData* loader_data) {
253 assert(Module_lock->owned_by_self(), "should have the Module_lock");
254
255 // Each ModuleEntryTable has exactly one unnamed module
256 if (loader_data->is_the_null_class_loader_data()) {
257 // For the boot loader, the java.lang.reflect.Module for the unnamed module
258 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
259 // this point initially create the ModuleEntry for the unnamed module.
260 _unnamed_module = new_entry(0, Handle(NULL), NULL, NULL, NULL, loader_data);
261 } else {
262 // For all other class loaders the java.lang.reflect.Module for their
263 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
264 oop module = java_lang_ClassLoader::unnamedModule(loader_data->class_loader());
265 _unnamed_module = new_entry(0, Handle(module), NULL, NULL, NULL, loader_data);
266
267 // Store pointer to the ModuleEntry in the unnamed module's java.lang.reflect.Module
268 // object.
269 java_lang_reflect_Module::set_module_entry(module, _unnamed_module);
270 }
271
272 // Add to bucket 0, no name to hash on
273 add_entry(0, _unnamed_module);
274 }
275
276 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle, Symbol* name,
277 Symbol* version, Symbol* location,
278 ClassLoaderData* loader_data) {
279 assert(Module_lock->owned_by_self(), "should have the Module_lock");
280 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
281
282 // Initialize everything BasicHashtable would
283 entry->set_next(NULL);
284 entry->set_hash(hash);
285 entry->set_literal(name);
286
287 // Initialize fields specific to a ModuleEntry
288 entry->init();
289 if (name != NULL) {
290 name->increment_refcount();
291 } else {
292 // Unnamed modules can read all other unnamed modules.
293 entry->set_can_read_all_unnamed();
294 }
295
296 if (!module_handle.is_null()) {
297 entry->set_module(loader_data->add_handle(module_handle));
298 }
299
300 entry->set_loader_data(loader_data);
301 entry->set_version(version);
302 entry->set_location(location);
303
304 TRACE_INIT_ID(entry);
305
306 return entry;
307 }
308
309 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
310 assert(Module_lock->owned_by_self(), "should have the Module_lock");
311 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
312 }
313
314 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
315 Symbol* module_name,
316 Symbol* module_version,
317 Symbol* module_location,
318 ClassLoaderData* loader_data) {
319 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
320 assert(Module_lock->owned_by_self(), "should have the Module_lock");
321 // Check if module already exists.
322 if (lookup_only(module_name) != NULL) {
323 return NULL;
324 } else {
325 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, module_name,
326 module_version, module_location, loader_data);
327 add_entry(index_for(module_name), entry);
328 return entry;
329 }
330 }
331
332 // lookup_only by Symbol* to find a ModuleEntry.
333 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
334 if (name == NULL) {
335 // Return this table's unnamed module
336 return unnamed_module();
337 }
338 int index = index_for(name);
339 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
340 if (m->name()->fast_compare(name) == 0) {
341 return m;
342 }
343 }
344 return NULL;
345 }
346
347 // Remove dead modules from all other alive modules' reads list.
348 // This should only occur at class unloading.
349 void ModuleEntryTable::purge_all_module_reads() {
350 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
351 for (int i = 0; i < table_size(); i++) {
352 for (ModuleEntry* entry = bucket(i);
353 entry != NULL;
354 entry = entry->next()) {
355 entry->purge_reads();
356 }
357 }
358 }
359
360 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
361 assert(Module_lock->owned_by_self(), "should have the Module_lock");
362 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
363 ModuleEntryTable* module_table = boot_loader_data->modules();
364
365 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
366
367 if (module_handle.is_null()) {
368 fatal("Unable to finalize module definition for java.base");
369 }
370
371 // Set java.lang.reflect.Module, version and location for java.base
372 ModuleEntry* jb_module = javabase_moduleEntry();
373 assert(jb_module != NULL, "java.base ModuleEntry not defined");
374 jb_module->set_version(version);
375 jb_module->set_location(location);
376 // Once java.base's ModuleEntry _module field is set with the known
377 // java.lang.reflect.Module, java.base is considered "defined" to the VM.
378 jb_module->set_module(boot_loader_data->add_handle(module_handle));
379
380 // Store pointer to the ModuleEntry for java.base in the java.lang.reflect.Module object.
381 java_lang_reflect_Module::set_module_entry(module_handle(), jb_module);
382 }
383
384 // Within java.lang.Class instances there is a java.lang.reflect.Module field
385 // that must be set with the defining module. During startup, prior to java.base's
386 // definition, classes needing their module field set are added to the fixup_module_list.
387 // Their module field is set once java.base's java.lang.reflect.Module is known to the VM.
388 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
389 if (module_handle.is_null()) {
390 fatal("Unable to patch the module field of classes loaded prior to java.base's definition, invalid java.lang.reflect.Module");
391 }
392
393 // Do the fixups for the basic primitive types
394 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
395 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
396 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
397 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
398 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
399 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
400 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
401 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
402 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
403
404 // Do the fixups for classes that have already been created.
405 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
406 int list_length = list->length();
407 for (int i = 0; i < list_length; i++) {
408 Klass* k = list->at(i);
409 assert(k->is_klass(), "List should only hold classes");
410 java_lang_Class::fixup_module_field(KlassHandle(k), module_handle);
411 k->class_loader_data()->dec_keep_alive();
412 }
413
414 delete java_lang_Class::fixup_module_field_list();
415 java_lang_Class::set_fixup_module_field_list(NULL);
416 }
417
418 void ModuleEntryTable::print(outputStream* st) {
419 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
420 table_size(), number_of_entries());
421 for (int i = 0; i < table_size(); i++) {
422 for (ModuleEntry* probe = bucket(i);
423 probe != NULL;
424 probe = probe->next()) {
425 probe->print(st);
426 }
427 }
428 }
429
430 void ModuleEntry::print(outputStream* st) {
431 ResourceMark rm;
432 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
433 p2i(this),
434 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
435 p2i(module()),
436 loader_data()->loader_name(),
437 version() != NULL ? version()->as_C_string() : "NULL",
438 location() != NULL ? location()->as_C_string() : "NULL",
439 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
440 }
441
442 void ModuleEntryTable::verify() {
443 int element_count = 0;
444 for (int i = 0; i < table_size(); i++) {
445 for (ModuleEntry* probe = bucket(i);
446 probe != NULL;
447 probe = probe->next()) {
448 probe->verify();
449 element_count++;
450 }
451 }
452 guarantee(number_of_entries() == element_count,
453 "Verify of Module Entry Table failed");
454 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Module Entry Table"));
455 }
456
457 void ModuleEntry::verify() {
458 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
459 }