1 /*
2 * Copyright (c) 2016, 2017, 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/moduleEntry.hpp"
27 #include "classfile/packageEntry.hpp"
28 #include "logging/log.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/symbol.hpp"
31 #include "runtime/handles.inline.hpp"
32 #include "trace/traceMacros.hpp"
33 #include "utilities/events.hpp"
34 #include "utilities/growableArray.hpp"
35 #include "utilities/hashtable.inline.hpp"
36 #include "utilities/ostream.hpp"
37
38 // Returns true if this package specifies m as a qualified export, including through an unnamed export
39 bool PackageEntry::is_qexported_to(ModuleEntry* m) const {
40 assert(Module_lock->owned_by_self(), "should have the Module_lock");
41 assert(m != NULL, "No module to lookup in this package's qualified exports list");
42 if (is_exported_allUnnamed() && !m->is_named()) {
43 return true;
44 } else if (!has_qual_exports_list()) {
45 return false;
46 } else {
47 return _qualified_exports->contains(m);
48 }
49 }
50
51 // Add a module to the package's qualified export list.
52 void PackageEntry::add_qexport(ModuleEntry* m) {
53 assert(Module_lock->owned_by_self(), "should have the Module_lock");
54 if (!has_qual_exports_list()) {
55 // Lazily create a package's qualified exports list.
56 // Initial size is small, do not anticipate export lists to be large.
57 _qualified_exports = new (ResourceObj::C_HEAP, mtModule) GrowableArray<ModuleEntry*>(QUAL_EXP_SIZE, true);
58 }
59
60 // Determine, based on this newly established export to module m,
61 // if this package's export list should be walked at a GC safepoint.
62 set_export_walk_required(m->loader_data());
63
64 // Establish exportability to module m
65 _qualified_exports->append_if_missing(m);
66 }
67
68 // If the module's loader, that an export is being established to, is
69 // not the same loader as this module's and is not one of the 3 builtin
70 // class loaders, then this package's export list must be walked at GC
71 // safepoint. Modules have the same life cycle as their defining class
72 // loaders and should be removed if dead.
73 void PackageEntry::set_export_walk_required(ClassLoaderData* m_loader_data) {
74 assert_locked_or_safepoint(Module_lock);
75 ModuleEntry* this_pkg_mod = module();
76 if (!_must_walk_exports &&
77 (this_pkg_mod == NULL || this_pkg_mod->loader_data() != m_loader_data) &&
78 !m_loader_data->is_builtin_class_loader_data()) {
79 _must_walk_exports = true;
80 if (log_is_enabled(Trace, modules)) {
81 ResourceMark rm;
82 assert(name() != NULL, "PackageEntry without a valid name");
83 log_trace(modules)("PackageEntry::set_export_walk_required(): package %s defined in module %s, exports list must be walked",
84 name()->as_C_string(),
85 (this_pkg_mod == NULL || this_pkg_mod->name() == NULL) ?
86 UNNAMED_MODULE : this_pkg_mod->name()->as_C_string());
87 }
88 }
89 }
90
91 // Set the package's exported states based on the value of the ModuleEntry.
92 void PackageEntry::set_exported(ModuleEntry* m) {
93 MutexLocker m1(Module_lock);
94 if (is_unqual_exported()) {
95 // An exception could be thrown, but choose to simply ignore.
96 // Illegal to convert an unqualified exported package to be qualifiedly exported
97 return;
98 }
99 if (module()->is_open()) {
100 // No-op for open modules since all packages are unqualifiedly exported
101 return;
102 }
103
104 if (m == NULL) {
105 // NULL indicates the package is being unqualifiedly exported. Clean up
106 // the qualified list at the next safepoint.
107 set_unqual_exported();
108 } else {
109 // Add the exported module
110 add_qexport(m);
111 }
112 }
113
114 // Set the package as exported to all unnamed modules unless the package is
115 // already unqualifiedly exported.
116 void PackageEntry::set_is_exported_allUnnamed() {
117 if (module()->is_open()) {
118 // No-op for open modules since all packages are unqualifiedly exported
119 return;
120 }
121
122 MutexLocker m1(Module_lock);
123 if (!is_unqual_exported()) {
124 _export_flags = PKG_EXP_ALLUNNAMED;
125 }
126 }
127
128 // Remove dead module entries within the package's exported list. Note that
129 // if all of the modules on the _qualified_exports get purged the list does not
130 // get deleted. This prevents the package from illegally transitioning from
131 // exported to non-exported.
132 void PackageEntry::purge_qualified_exports() {
133 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
134 if (_must_walk_exports &&
135 _qualified_exports != NULL &&
136 !_qualified_exports->is_empty()) {
137 ModuleEntry* pkg_module = module();
138
139 // This package's _must_walk_exports flag will be reset based
140 // on the remaining live modules on the exports list.
141 _must_walk_exports = false;
142
143 if (log_is_enabled(Trace, modules)) {
144 ResourceMark rm;
145 assert(name() != NULL, "PackageEntry without a valid name");
146 ModuleEntry* pkg_mod = module();
147 log_trace(modules)("PackageEntry::purge_qualified_exports(): package %s defined in module %s, exports list being walked",
148 name()->as_C_string(),
149 (pkg_mod == NULL || pkg_mod->name() == NULL) ? UNNAMED_MODULE : pkg_mod->name()->as_C_string());
150 }
151
152 // Go backwards because this removes entries that are dead.
153 int len = _qualified_exports->length();
154 for (int idx = len - 1; idx >= 0; idx--) {
155 ModuleEntry* module_idx = _qualified_exports->at(idx);
156 ClassLoaderData* cld_idx = module_idx->loader_data();
157 if (cld_idx->is_unloading()) {
158 _qualified_exports->delete_at(idx);
159 } else {
160 // Update the need to walk this package's exports based on live modules
161 set_export_walk_required(cld_idx);
162 }
163 }
164 }
165 }
166
167 void PackageEntry::delete_qualified_exports() {
168 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
169 if (_qualified_exports != NULL) {
170 delete _qualified_exports;
171 }
172 _qualified_exports = NULL;
173 }
174
175 PackageEntryTable::PackageEntryTable(int table_size)
176 : Hashtable<Symbol*, mtModule>(table_size, sizeof(PackageEntry))
177 {
178 }
179
180 PackageEntryTable::~PackageEntryTable() {
181 assert_locked_or_safepoint(Module_lock);
182
183 // Walk through all buckets and all entries in each bucket,
184 // freeing each entry.
185 for (int i = 0; i < table_size(); ++i) {
186 for (PackageEntry* p = bucket(i); p != NULL;) {
187 PackageEntry* to_remove = p;
188 // read next before freeing.
189 p = p->next();
190
191 // Clean out the C heap allocated qualified exports list first before freeing the entry
192 to_remove->delete_qualified_exports();
193 to_remove->name()->decrement_refcount();
194
195 // Unlink from the Hashtable prior to freeing
196 unlink_entry(to_remove);
197 FREE_C_HEAP_ARRAY(char, to_remove);
198 }
199 }
200 assert(number_of_entries() == 0, "should have removed all entries");
201 assert(new_entry_free_list() == NULL, "entry present on PackageEntryTable's free list");
202 free_buckets();
203 }
204
205 PackageEntry* PackageEntryTable::new_entry(unsigned int hash, Symbol* name, ModuleEntry* module) {
206 assert(Module_lock->owned_by_self(), "should have the Module_lock");
207 PackageEntry* entry = (PackageEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
208
209 // Initialize everything BasicHashtable would
210 entry->set_next(NULL);
211 entry->set_hash(hash);
212 entry->set_literal(name);
213
214 TRACE_INIT_ID(entry);
215
216 // Initialize fields specific to a PackageEntry
217 entry->init();
218 entry->name()->increment_refcount();
219 entry->set_module(module);
220 return entry;
221 }
222
223 void PackageEntryTable::add_entry(int index, PackageEntry* new_entry) {
224 assert(Module_lock->owned_by_self(), "should have the Module_lock");
225 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
226 }
227
228 // Create package in loader's package entry table and return the entry.
229 // If entry already exists, return null. Assume Module lock was taken by caller.
230 PackageEntry* PackageEntryTable::locked_create_entry_or_null(Symbol* name, ModuleEntry* module) {
231 assert(Module_lock->owned_by_self(), "should have the Module_lock");
232 // Check if package already exists. Return NULL if it does.
233 if (lookup_only(name) != NULL) {
234 return NULL;
235 } else {
236 PackageEntry* entry = new_entry(compute_hash(name), name, module);
237 add_entry(index_for(name), entry);
238 return entry;
239 }
240 }
241
242 PackageEntry* PackageEntryTable::lookup(Symbol* name, ModuleEntry* module) {
243 PackageEntry* p = lookup_only(name);
244 if (p != NULL) {
245 return p;
246 } else {
247 // If not found, add to table. Grab the PackageEntryTable lock first.
248 MutexLocker ml(Module_lock);
249
250 // Since look-up was done lock-free, we need to check if another thread beat
251 // us in the race to insert the package.
252 PackageEntry* test = lookup_only(name);
253 if (test != NULL) {
254 // A race occurred and another thread introduced the package.
255 return test;
256 } else {
257 assert(module != NULL, "module should never be null");
258 PackageEntry* entry = new_entry(compute_hash(name), name, module);
259 add_entry(index_for(name), entry);
260 return entry;
261 }
262 }
263 }
264
265 PackageEntry* PackageEntryTable::lookup_only(Symbol* name) {
266 int index = index_for(name);
267 for (PackageEntry* p = bucket(index); p != NULL; p = p->next()) {
268 if (p->name()->fast_compare(name) == 0) {
269 return p;
270 }
271 }
272 return NULL;
273 }
274
275 // Called when a define module for java.base is being processed.
276 // Verify the packages loaded thus far are in java.base's package list.
277 void PackageEntryTable::verify_javabase_packages(GrowableArray<Symbol*> *pkg_list) {
278 for (int i = 0; i < table_size(); i++) {
279 for (PackageEntry* entry = bucket(i);
280 entry != NULL;
281 entry = entry->next()) {
282 ModuleEntry* m = entry->module();
283 Symbol* module_name = (m == NULL ? NULL : m->name());
284 if (module_name != NULL &&
285 (module_name->fast_compare(vmSymbols::java_base()) == 0) &&
286 !pkg_list->contains(entry->name())) {
287 ResourceMark rm;
288 vm_exit_during_initialization("A non-" JAVA_BASE_NAME " package was loaded prior to module system initialization", entry->name()->as_C_string());
289 }
290 }
291 }
292
293 }
294
295 // iteration of qualified exports
296 void PackageEntry::package_exports_do(ModuleClosure* const f) {
297 assert_locked_or_safepoint(Module_lock);
298 assert(f != NULL, "invariant");
299
300 if (has_qual_exports_list()) {
301 int qe_len = _qualified_exports->length();
302
303 for (int i = 0; i < qe_len; ++i) {
304 f->do_module(_qualified_exports->at(i));
305 }
306 }
307 }
308
309 bool PackageEntry::exported_pending_delete() const {
310 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
311 return (is_unqual_exported() && _qualified_exports != NULL);
312 }
313
314 // Remove dead entries from all packages' exported list
315 void PackageEntryTable::purge_all_package_exports() {
316 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
317 for (int i = 0; i < table_size(); i++) {
318 for (PackageEntry* entry = bucket(i);
319 entry != NULL;
320 entry = entry->next()) {
321 if (entry->exported_pending_delete()) {
322 // exported list is pending deletion due to a transition
323 // from qualified to unqualified
324 entry->delete_qualified_exports();
325 } else if (entry->is_qual_exported()) {
326 entry->purge_qualified_exports();
327 }
328 }
329 }
330 }
331
332 void PackageEntryTable::print(outputStream* st) {
333 st->print_cr("Package Entry Table (table_size=%d, entries=%d)",
334 table_size(), number_of_entries());
335 for (int i = 0; i < table_size(); i++) {
336 for (PackageEntry* probe = bucket(i);
337 probe != NULL;
338 probe = probe->next()) {
339 probe->print(st);
340 }
341 }
342 }
343
344 // This function may be called from debuggers so access private fields directly
345 // to prevent triggering locking-related asserts that could result from calling
346 // getter methods.
347 void PackageEntry::print(outputStream* st) {
348 ResourceMark rm;
349 st->print_cr("package entry " PTR_FORMAT " name %s module %s classpath_index "
350 INT32_FORMAT " is_exported_unqualified %d is_exported_allUnnamed %d " "next " PTR_FORMAT,
351 p2i(this), name()->as_C_string(),
352 (module()->is_named() ? module()->name()->as_C_string() : UNNAMED_MODULE),
353 _classpath_index, _export_flags == PKG_EXP_UNQUALIFIED,
354 _export_flags == PKG_EXP_ALLUNNAMED, p2i(next()));
355 }
356
357 void PackageEntryTable::verify() {
358 int element_count = 0;
359 for (int index = 0; index < table_size(); index++) {
360 for (PackageEntry* probe = bucket(index);
361 probe != NULL;
362 probe = probe->next()) {
363 probe->verify();
364 element_count++;
365 }
366 }
367 guarantee(number_of_entries() == element_count,
368 "Verify of Package Entry Table failed");
369 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Package Entry Table"));
370 }
371
372 void PackageEntry::verify() {
373 guarantee(name() != NULL, "A package entry must have a corresponding symbol name.");
374 }