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 (this->has_default_read_edges() && !m->is_named()) {
112 ClassLoaderData* cld = m->loader_data();
113 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
114 return true; //default read edge
115 }
116 }
117 if (!has_reads()) {
118 return false;
119 } else {
120 return _reads->contains(m);
121 }
122 }
123
124 // Add a new module to this module's reads list
125 void ModuleEntry::add_read(ModuleEntry* m) {
126 MutexLocker m1(Module_lock);
127 if (m == NULL) {
128 set_can_read_all_unnamed();
129 } else {
130 if (_reads == NULL) {
131 // Lazily create a module's reads list
132 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
133 }
134
135 // Determine, based on this newly established read edge to module m,
136 // if this module's read list should be walked at a GC safepoint.
137 set_read_walk_required(m->loader_data());
138
139 // Establish readability to module m
140 _reads->append_if_missing(m);
141 }
142 }
143
144 // If the module's loader, that a read edge is being established to, is
145 // not the same loader as this module's and is not one of the 3 builtin
146 // class loaders, then this module's reads list must be walked at GC
147 // safepoint. Modules have the same life cycle as their defining class
148 // loaders and should be removed if dead.
149 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
150 assert_locked_or_safepoint(Module_lock);
151 if (!_must_walk_reads &&
152 loader_data() != m_loader_data &&
153 !m_loader_data->is_builtin_class_loader_data()) {
154 _must_walk_reads = true;
155 if (log_is_enabled(Trace, modules)) {
156 ResourceMark rm;
157 log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
158 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
159 }
160 }
161 }
162
163 bool ModuleEntry::has_reads() const {
164 assert_locked_or_safepoint(Module_lock);
165 return ((_reads != NULL) && !_reads->is_empty());
166 }
167
168 // Purge dead module entries out of reads list.
169 void ModuleEntry::purge_reads() {
170 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
171
172 if (_must_walk_reads && has_reads()) {
173 // This module's _must_walk_reads flag will be reset based
174 // on the remaining live modules on the reads list.
175 _must_walk_reads = false;
176
177 if (log_is_enabled(Trace, modules)) {
178 ResourceMark rm;
179 log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked",
180 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
181 }
182
183 // Go backwards because this removes entries that are dead.
184 int len = _reads->length();
185 for (int idx = len - 1; idx >= 0; idx--) {
186 ModuleEntry* module_idx = _reads->at(idx);
187 ClassLoaderData* cld_idx = module_idx->loader_data();
188 if (cld_idx->is_unloading()) {
189 _reads->delete_at(idx);
190 } else {
191 // Update the need to walk this module's reads based on live modules
192 set_read_walk_required(cld_idx);
193 }
194 }
195 }
196 }
197
198 void ModuleEntry::module_reads_do(ModuleClosure* const f) {
199 assert_locked_or_safepoint(Module_lock);
200 assert(f != NULL, "invariant");
201
202 if (has_reads()) {
203 int reads_len = _reads->length();
204 for (int i = 0; i < reads_len; ++i) {
205 f->do_module(_reads->at(i));
206 }
207 }
208 }
209
210 void ModuleEntry::delete_reads() {
211 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
212 delete _reads;
213 _reads = NULL;
214 }
215
216 ModuleEntryTable::ModuleEntryTable(int table_size)
217 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry)), _unnamed_module(NULL)
218 {
219 }
220
221 ModuleEntryTable::~ModuleEntryTable() {
222 assert_locked_or_safepoint(Module_lock);
223
224 // Walk through all buckets and all entries in each bucket,
225 // freeing each entry.
226 for (int i = 0; i < table_size(); ++i) {
227 for (ModuleEntry* m = bucket(i); m != NULL;) {
228 ModuleEntry* to_remove = m;
229 // read next before freeing.
230 m = m->next();
231
232 ResourceMark rm;
233 log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
234 to_remove->name()->as_C_string() : UNNAMED_MODULE);
235
236 // Clean out the C heap allocated reads list first before freeing the entry
237 to_remove->delete_reads();
238 if (to_remove->name() != NULL) {
239 to_remove->name()->decrement_refcount();
240 }
241 if (to_remove->version() != NULL) {
242 to_remove->version()->decrement_refcount();
243 }
244 if (to_remove->location() != NULL) {
245 to_remove->location()->decrement_refcount();
246 }
247
248 // Unlink from the Hashtable prior to freeing
249 unlink_entry(to_remove);
250 FREE_C_HEAP_ARRAY(char, to_remove);
251 }
252 }
253 assert(number_of_entries() == 0, "should have removed all entries");
254 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
255 free_buckets();
256 }
257
258 void ModuleEntryTable::create_unnamed_module(ClassLoaderData* loader_data) {
259 assert(Module_lock->owned_by_self(), "should have the Module_lock");
260
261 // Each ModuleEntryTable has exactly one unnamed module
262 if (loader_data->is_the_null_class_loader_data()) {
263 // For the boot loader, the java.lang.reflect.Module for the unnamed module
264 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
265 // this point initially create the ModuleEntry for the unnamed module.
266 _unnamed_module = new_entry(0, Handle(NULL), NULL, NULL, NULL, loader_data);
267 } else {
268 // For all other class loaders the java.lang.reflect.Module for their
269 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
270 oop module = java_lang_ClassLoader::unnamedModule(loader_data->class_loader());
271 _unnamed_module = new_entry(0, Handle(module), NULL, NULL, NULL, loader_data);
272
273 // Store pointer to the ModuleEntry in the unnamed module's java.lang.reflect.Module
274 // object.
275 java_lang_reflect_Module::set_module_entry(module, _unnamed_module);
276 }
277
278 // Add to bucket 0, no name to hash on
279 add_entry(0, _unnamed_module);
280 }
281
282 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle, Symbol* name,
283 Symbol* version, Symbol* location,
284 ClassLoaderData* loader_data) {
285 assert(Module_lock->owned_by_self(), "should have the Module_lock");
286 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
287
288 // Initialize everything BasicHashtable would
289 entry->set_next(NULL);
290 entry->set_hash(hash);
291 entry->set_literal(name);
292
293 // Initialize fields specific to a ModuleEntry
294 entry->init();
295 if (name != NULL) {
296 name->increment_refcount();
297 } else {
298 // Unnamed modules can read all other unnamed modules.
299 entry->set_can_read_all_unnamed();
300 }
301
302 if (!module_handle.is_null()) {
303 entry->set_module(loader_data->add_handle(module_handle));
304 }
305
306 entry->set_loader_data(loader_data);
307 entry->set_version(version);
308 entry->set_location(location);
309
310 TRACE_INIT_MODULE_ID(entry);
311
312 return entry;
313 }
314
315 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
316 assert(Module_lock->owned_by_self(), "should have the Module_lock");
317 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
318 }
319
320 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
321 Symbol* module_name,
322 Symbol* module_version,
323 Symbol* module_location,
324 ClassLoaderData* loader_data) {
325 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
326 assert(Module_lock->owned_by_self(), "should have the Module_lock");
327 // Check if module already exists.
328 if (lookup_only(module_name) != NULL) {
329 return NULL;
330 } else {
331 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, module_name,
332 module_version, module_location, loader_data);
333 add_entry(index_for(module_name), entry);
334 return entry;
335 }
336 }
337
338 // lookup_only by Symbol* to find a ModuleEntry.
339 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
340 if (name == NULL) {
341 // Return this table's unnamed module
342 return unnamed_module();
343 }
344 int index = index_for(name);
345 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
346 if (m->name()->fast_compare(name) == 0) {
347 return m;
348 }
349 }
350 return NULL;
351 }
352
353 // Remove dead modules from all other alive modules' reads list.
354 // This should only occur at class unloading.
355 void ModuleEntryTable::purge_all_module_reads() {
356 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
357 for (int i = 0; i < table_size(); i++) {
358 for (ModuleEntry* entry = bucket(i);
359 entry != NULL;
360 entry = entry->next()) {
361 entry->purge_reads();
362 }
363 }
364 }
365
366 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
367 assert(Module_lock->owned_by_self(), "should have the Module_lock");
368 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
369 ModuleEntryTable* module_table = boot_loader_data->modules();
370
371 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
372
373 if (module_handle.is_null()) {
374 fatal("Unable to finalize module definition for java.base");
375 }
376
377 // Set java.lang.reflect.Module, version and location for java.base
378 ModuleEntry* jb_module = javabase_moduleEntry();
379 assert(jb_module != NULL, "java.base ModuleEntry not defined");
380 jb_module->set_version(version);
381 jb_module->set_location(location);
382 // Once java.base's ModuleEntry _module field is set with the known
383 // java.lang.reflect.Module, java.base is considered "defined" to the VM.
384 jb_module->set_module(boot_loader_data->add_handle(module_handle));
385
386 // Store pointer to the ModuleEntry for java.base in the java.lang.reflect.Module object.
387 java_lang_reflect_Module::set_module_entry(module_handle(), jb_module);
388 }
389
390 // Within java.lang.Class instances there is a java.lang.reflect.Module field
391 // that must be set with the defining module. During startup, prior to java.base's
392 // definition, classes needing their module field set are added to the fixup_module_list.
393 // Their module field is set once java.base's java.lang.reflect.Module is known to the VM.
394 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
395 if (module_handle.is_null()) {
396 fatal("Unable to patch the module field of classes loaded prior to java.base's definition, invalid java.lang.reflect.Module");
397 }
398
399 // Do the fixups for the basic primitive types
400 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
401 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
402 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
403 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
404 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
405 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
406 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
407 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
408 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
409
410 // Do the fixups for classes that have already been created.
411 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
412 int list_length = list->length();
413 for (int i = 0; i < list_length; i++) {
414 Klass* k = list->at(i);
415 assert(k->is_klass(), "List should only hold classes");
416 java_lang_Class::fixup_module_field(KlassHandle(k), module_handle);
417 k->class_loader_data()->dec_keep_alive();
418 }
419
420 delete java_lang_Class::fixup_module_field_list();
421 java_lang_Class::set_fixup_module_field_list(NULL);
422 }
423
424 void ModuleEntryTable::print(outputStream* st) {
425 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
426 table_size(), number_of_entries());
427 for (int i = 0; i < table_size(); i++) {
428 for (ModuleEntry* probe = bucket(i);
429 probe != NULL;
430 probe = probe->next()) {
431 probe->print(st);
432 }
433 }
434 }
435
436 void ModuleEntry::print(outputStream* st) {
437 ResourceMark rm;
438 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
439 p2i(this),
440 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
441 p2i(module()),
442 loader_data()->loader_name(),
443 version() != NULL ? version()->as_C_string() : "NULL",
444 location() != NULL ? location()->as_C_string() : "NULL",
445 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
446 }
447
448 void ModuleEntryTable::verify() {
449 int element_count = 0;
450 for (int i = 0; i < table_size(); i++) {
451 for (ModuleEntry* probe = bucket(i);
452 probe != NULL;
453 probe = probe->next()) {
454 probe->verify();
455 element_count++;
456 }
457 }
458 guarantee(number_of_entries() == element_count,
459 "Verify of Module Entry Table failed");
460 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Module Entry Table"));
461 }
462
463 void ModuleEntry::verify() {
464 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
465 }