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 = "";
61 loc = location()->as_C_string();
62 if (strncmp(loc, "jrt:/java.", 10) != 0 && strncmp(loc, "jrt:/jdk.", 9) != 0) {
63 return true;
64 }
65 }
66 return false;
67 }
68
69 void ModuleEntry::set_version(Symbol* version) {
70 if (_version != NULL) {
71 // _version symbol's refcounts are managed by ModuleEntry,
72 // must decrement the old one before updating.
73 _version->decrement_refcount();
74 }
75
76 _version = version;
77
78 if (version != NULL) {
79 version->increment_refcount();
80 }
81 }
82
83 // Returns the shared ProtectionDomain
84 Handle ModuleEntry::shared_protection_domain() {
85 return Handle(JNIHandles::resolve(_pd));
86 }
87
88 // Set the shared ProtectionDomain atomically
89 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
90 Handle pd_h) {
91 // Create a JNI handle for the shared ProtectionDomain and save it atomically.
92 // If someone beats us setting the _pd cache, the created JNI handle is destroyed.
93 jobject obj = loader_data->add_handle(pd_h);
94 if (Atomic::cmpxchg_ptr(obj, &_pd, NULL) != NULL) {
95 loader_data->remove_handle(obj);
96 }
97 }
98
99 // Returns true if this module can read module m
100 bool ModuleEntry::can_read(ModuleEntry* m) const {
101 assert(m != NULL, "No module to lookup in this module's reads list");
102
103 // Unnamed modules read everyone and all modules
104 // read java.base. If either of these conditions
105 // hold, readability has been established.
106 if (!this->is_named() ||
107 (m == ModuleEntryTable::javabase_moduleEntry())) {
108 return true;
109 }
110
111 MutexLocker m1(Module_lock);
112 if (!has_reads()) {
113 return false;
114 } else {
115 return _reads->contains(m);
116 }
117 }
118
119 // Add a new module to this module's reads list
120 void ModuleEntry::add_read(ModuleEntry* m) {
121 MutexLocker m1(Module_lock);
122 if (m == NULL) {
123 set_can_read_all_unnamed();
124 } else {
125 if (_reads == NULL) {
126 // Lazily create a module's reads list
127 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
128 }
129
130 // Determine, based on this newly established read edge to module m,
131 // if this module's read list should be walked at a GC safepoint.
132 set_read_walk_required(m->loader_data());
133
134 // Establish readability to module m
135 _reads->append_if_missing(m);
136 }
137 }
138
139 // If the module's loader, that a read edge is being established to, is
140 // not the same loader as this module's and is not one of the 3 builtin
141 // class loaders, then this module's reads list must be walked at GC
142 // safepoint. Modules have the same life cycle as their defining class
143 // loaders and should be removed if dead.
144 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
145 assert_locked_or_safepoint(Module_lock);
146 if (!_must_walk_reads &&
147 loader_data() != m_loader_data &&
148 !m_loader_data->is_builtin_class_loader_data()) {
149 _must_walk_reads = true;
150 if (log_is_enabled(Trace, modules)) {
151 ResourceMark rm;
152 log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
153 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
154 }
155 }
156 }
157
158 bool ModuleEntry::has_reads() const {
159 assert_locked_or_safepoint(Module_lock);
160 return ((_reads != NULL) && !_reads->is_empty());
161 }
162
163 // Purge dead module entries out of reads list.
164 void ModuleEntry::purge_reads() {
165 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
166
167 if (_must_walk_reads && has_reads()) {
168 // This module's _must_walk_reads flag will be reset based
169 // on the remaining live modules on the reads list.
170 _must_walk_reads = false;
171
172 if (log_is_enabled(Trace, modules)) {
173 ResourceMark rm;
174 log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked",
175 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
176 }
177
178 // Go backwards because this removes entries that are dead.
179 int len = _reads->length();
180 for (int idx = len - 1; idx >= 0; idx--) {
181 ModuleEntry* module_idx = _reads->at(idx);
182 ClassLoaderData* cld_idx = module_idx->loader_data();
183 if (cld_idx->is_unloading()) {
184 _reads->delete_at(idx);
185 } else {
186 // Update the need to walk this module's reads based on live modules
187 set_read_walk_required(cld_idx);
188 }
189 }
190 }
191 }
192
193 void ModuleEntry::module_reads_do(ModuleClosure* const f) {
194 assert_locked_or_safepoint(Module_lock);
195 assert(f != NULL, "invariant");
196
197 if (has_reads()) {
198 int reads_len = _reads->length();
199 for (int i = 0; i < reads_len; ++i) {
200 f->do_module(_reads->at(i));
201 }
202 }
203 }
204
205 void ModuleEntry::delete_reads() {
206 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
207 delete _reads;
208 _reads = NULL;
209 }
210
211 ModuleEntryTable::ModuleEntryTable(int table_size)
212 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry)), _unnamed_module(NULL)
213 {
214 }
215
216 ModuleEntryTable::~ModuleEntryTable() {
217 assert_locked_or_safepoint(Module_lock);
218
219 // Walk through all buckets and all entries in each bucket,
220 // freeing each entry.
221 for (int i = 0; i < table_size(); ++i) {
222 for (ModuleEntry* m = bucket(i); m != NULL;) {
223 ModuleEntry* to_remove = m;
224 // read next before freeing.
225 m = m->next();
226
227 ResourceMark rm;
228 log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
229 to_remove->name()->as_C_string() : UNNAMED_MODULE);
230
231 // Clean out the C heap allocated reads list first before freeing the entry
232 to_remove->delete_reads();
233 if (to_remove->name() != NULL) {
234 to_remove->name()->decrement_refcount();
235 }
236 if (to_remove->version() != NULL) {
237 to_remove->version()->decrement_refcount();
238 }
239 if (to_remove->location() != NULL) {
240 to_remove->location()->decrement_refcount();
241 }
242
243 // Unlink from the Hashtable prior to freeing
244 unlink_entry(to_remove);
245 FREE_C_HEAP_ARRAY(char, to_remove);
246 }
247 }
248 assert(number_of_entries() == 0, "should have removed all entries");
249 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
250 free_buckets();
251 }
252
253 void ModuleEntryTable::create_unnamed_module(ClassLoaderData* loader_data) {
254 assert(Module_lock->owned_by_self(), "should have the Module_lock");
255
256 // Each ModuleEntryTable has exactly one unnamed module
257 if (loader_data->is_the_null_class_loader_data()) {
258 // For the boot loader, the java.lang.reflect.Module for the unnamed module
259 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
260 // this point initially create the ModuleEntry for the unnamed module.
261 _unnamed_module = new_entry(0, Handle(NULL), NULL, NULL, NULL, loader_data);
262 } else {
263 // For all other class loaders the java.lang.reflect.Module for their
264 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
265 oop module = java_lang_ClassLoader::unnamedModule(loader_data->class_loader());
266 _unnamed_module = new_entry(0, Handle(module), NULL, NULL, NULL, loader_data);
267
268 // Store pointer to the ModuleEntry in the unnamed module's java.lang.reflect.Module
269 // object.
270 java_lang_reflect_Module::set_module_entry(module, _unnamed_module);
271 }
272
273 // Add to bucket 0, no name to hash on
274 add_entry(0, _unnamed_module);
275 }
276
277 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle, Symbol* name,
278 Symbol* version, Symbol* location,
279 ClassLoaderData* loader_data) {
280 assert(Module_lock->owned_by_self(), "should have the Module_lock");
281 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
282
283 // Initialize everything BasicHashtable would
284 entry->set_next(NULL);
285 entry->set_hash(hash);
286 entry->set_literal(name);
287
288 // Initialize fields specific to a ModuleEntry
289 entry->init();
290 if (name != NULL) {
291 name->increment_refcount();
292 } else {
293 // Unnamed modules can read all other unnamed modules.
294 entry->set_can_read_all_unnamed();
295 }
296
297 if (!module_handle.is_null()) {
298 entry->set_module(loader_data->add_handle(module_handle));
299 }
300
301 entry->set_loader_data(loader_data);
302 entry->set_version(version);
303 entry->set_location(location);
304
305 TRACE_INIT_MODULE_ID(entry);
306
307 return entry;
308 }
309
310 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
311 assert(Module_lock->owned_by_self(), "should have the Module_lock");
312 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
313 }
314
315 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
316 Symbol* module_name,
317 Symbol* module_version,
318 Symbol* module_location,
319 ClassLoaderData* loader_data) {
320 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
321 assert(Module_lock->owned_by_self(), "should have the Module_lock");
322 // Check if module already exists.
323 if (lookup_only(module_name) != NULL) {
324 return NULL;
325 } else {
326 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, module_name,
327 module_version, module_location, loader_data);
328 add_entry(index_for(module_name), entry);
329 return entry;
330 }
331 }
332
333 // lookup_only by Symbol* to find a ModuleEntry.
334 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
335 if (name == NULL) {
336 // Return this table's unnamed module
337 return unnamed_module();
338 }
339 int index = index_for(name);
340 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
341 if (m->name()->fast_compare(name) == 0) {
342 return m;
343 }
344 }
345 return NULL;
346 }
347
348 // Remove dead modules from all other alive modules' reads list.
349 // This should only occur at class unloading.
350 void ModuleEntryTable::purge_all_module_reads() {
351 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
352 for (int i = 0; i < table_size(); i++) {
353 for (ModuleEntry* entry = bucket(i);
354 entry != NULL;
355 entry = entry->next()) {
356 entry->purge_reads();
357 }
358 }
359 }
360
361 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
362 assert(Module_lock->owned_by_self(), "should have the Module_lock");
363 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
364 ModuleEntryTable* module_table = boot_loader_data->modules();
365
366 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
367
368 if (module_handle.is_null()) {
369 fatal("Unable to finalize module definition for java.base");
370 }
371
372 // Set java.lang.reflect.Module, version and location for java.base
373 ModuleEntry* jb_module = javabase_moduleEntry();
374 assert(jb_module != NULL, "java.base ModuleEntry not defined");
375 jb_module->set_version(version);
376 jb_module->set_location(location);
377 // Once java.base's ModuleEntry _module field is set with the known
378 // java.lang.reflect.Module, java.base is considered "defined" to the VM.
379 jb_module->set_module(boot_loader_data->add_handle(module_handle));
380
381 // Store pointer to the ModuleEntry for java.base in the java.lang.reflect.Module object.
382 java_lang_reflect_Module::set_module_entry(module_handle(), jb_module);
383 }
384
385 // Within java.lang.Class instances there is a java.lang.reflect.Module field
386 // that must be set with the defining module. During startup, prior to java.base's
387 // definition, classes needing their module field set are added to the fixup_module_list.
388 // Their module field is set once java.base's java.lang.reflect.Module is known to the VM.
389 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
390 if (module_handle.is_null()) {
391 fatal("Unable to patch the module field of classes loaded prior to java.base's definition, invalid java.lang.reflect.Module");
392 }
393
394 // Do the fixups for the basic primitive types
395 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
396 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
397 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
398 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
399 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
400 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
401 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
402 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
403 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
404
405 // Do the fixups for classes that have already been created.
406 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
407 int list_length = list->length();
408 for (int i = 0; i < list_length; i++) {
409 Klass* k = list->at(i);
410 assert(k->is_klass(), "List should only hold classes");
411 java_lang_Class::fixup_module_field(KlassHandle(k), module_handle);
412 k->class_loader_data()->dec_keep_alive();
413 }
414
415 delete java_lang_Class::fixup_module_field_list();
416 java_lang_Class::set_fixup_module_field_list(NULL);
417 }
418
419 void ModuleEntryTable::print(outputStream* st) {
420 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
421 table_size(), number_of_entries());
422 for (int i = 0; i < table_size(); i++) {
423 for (ModuleEntry* probe = bucket(i);
424 probe != NULL;
425 probe = probe->next()) {
426 probe->print(st);
427 }
428 }
429 }
430
431 void ModuleEntry::print(outputStream* st) {
432 ResourceMark rm;
433 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
434 p2i(this),
435 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
436 p2i(module()),
437 loader_data()->loader_name(),
438 version() != NULL ? version()->as_C_string() : "NULL",
439 location() != NULL ? location()->as_C_string() : "NULL",
440 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
441 }
442
443 void ModuleEntryTable::verify() {
444 int element_count = 0;
445 for (int i = 0; i < table_size(); i++) {
446 for (ModuleEntry* probe = bucket(i);
447 probe != NULL;
448 probe = probe->next()) {
449 probe->verify();
450 element_count++;
451 }
452 }
453 guarantee(number_of_entries() == element_count,
454 "Verify of Module Entry Table failed");
455 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Module Entry Table"));
456 }
457
458 void ModuleEntry::verify() {
459 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
460 }