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