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/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(m != NULL, "No module to lookup in this package's qualified exports list");
41 MutexLocker m1(Module_lock);
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
100 if (m == NULL) {
101 // NULL indicates the package is being unqualifiedly exported
102 if (has_qual_exports_list()) {
103 // Legit to transition a package from being qualifiedly exported
104 // to unqualified. Clean up the qualified lists at the next
105 // safepoint.
106 _exported_pending_delete = _qualified_exports;
107 }
108
109 // Mark package as unqualifiedly exported
110 set_unqual_exported();
111
112 } else {
113 // Add the exported module
114 add_qexport(m);
115 }
116 }
117
118 void PackageEntry::set_is_exported_allUnnamed() {
119 MutexLocker m1(Module_lock);
120 if (!is_unqual_exported()) {
121 _is_exported_allUnnamed = true;
122 }
123 }
124
125 // Remove dead module entries within the package's exported list.
126 void PackageEntry::purge_qualified_exports() {
127 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
128 if (_must_walk_exports &&
129 _qualified_exports != NULL &&
130 !_qualified_exports->is_empty()) {
131 ModuleEntry* pkg_module = module();
132
133 // This package's _must_walk_exports flag will be reset based
134 // on the remaining live modules on the exports list.
135 _must_walk_exports = false;
136
137 if (log_is_enabled(Trace, modules)) {
138 ResourceMark rm;
139 assert(name() != NULL, "PackageEntry without a valid name");
140 ModuleEntry* pkg_mod = module();
141 log_trace(modules)("PackageEntry::purge_qualified_exports(): package %s defined in module %s, exports list being walked",
142 name()->as_C_string(),
143 (pkg_mod == NULL || pkg_mod->name() == NULL) ? UNNAMED_MODULE : pkg_mod->name()->as_C_string());
144 }
145
146 // Go backwards because this removes entries that are dead.
147 int len = _qualified_exports->length();
148 for (int idx = len - 1; idx >= 0; idx--) {
149 ModuleEntry* module_idx = _qualified_exports->at(idx);
150 ClassLoaderData* cld_idx = module_idx->loader_data();
151 if (cld_idx->is_unloading()) {
152 _qualified_exports->delete_at(idx);
153 } else {
154 // Update the need to walk this package's exports based on live modules
155 set_export_walk_required(cld_idx);
156 }
157 }
158 }
159 }
160
161 void PackageEntry::delete_qualified_exports() {
162 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
163 if (_exported_pending_delete != NULL) {
164 // If a transition occurred from qualified to unqualified, the _qualified_exports
165 // field should have been NULL'ed out.
166 assert(_qualified_exports == NULL, "Package's exported pending delete, exported list should not be active");
167 delete _exported_pending_delete;
168 }
169
170 if (_qualified_exports != NULL) {
171 delete _qualified_exports;
172 }
173
174 _exported_pending_delete = NULL;
175 _qualified_exports = NULL;
176 }
177
178 PackageEntryTable::PackageEntryTable(int table_size)
179 : Hashtable<Symbol*, mtModule>(table_size, sizeof(PackageEntry))
180 {
181 }
182
183 PackageEntryTable::~PackageEntryTable() {
184 assert_locked_or_safepoint(Module_lock);
185
186 // Walk through all buckets and all entries in each bucket,
187 // freeing each entry.
188 for (int i = 0; i < table_size(); ++i) {
189 for (PackageEntry* p = bucket(i); p != NULL;) {
190 PackageEntry* to_remove = p;
191 // read next before freeing.
192 p = p->next();
193
194 // Clean out the C heap allocated qualified exports list first before freeing the entry
195 to_remove->delete_qualified_exports();
196 to_remove->name()->decrement_refcount();
197
198 // Unlink from the Hashtable prior to freeing
199 unlink_entry(to_remove);
200 FREE_C_HEAP_ARRAY(char, to_remove);
201 }
202 }
203 assert(number_of_entries() == 0, "should have removed all entries");
204 assert(new_entry_free_list() == NULL, "entry present on PackageEntryTable's free list");
205 free_buckets();
206 }
207
208 PackageEntry* PackageEntryTable::new_entry(unsigned int hash, Symbol* name, ModuleEntry* module) {
209 assert(Module_lock->owned_by_self(), "should have the Module_lock");
210 PackageEntry* entry = (PackageEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
211
212 // Initialize everything BasicHashtable would
213 entry->set_next(NULL);
214 entry->set_hash(hash);
215 entry->set_literal(name);
216
217 TRACE_INIT_PACKAGE_ID(entry);
218
219 // Initialize fields specific to a PackageEntry
220 entry->init();
221 entry->name()->increment_refcount();
222 if (!module->is_named()) {
223 // Set the exported state to true because all packages
224 // within the unnamed module are unqualifiedly exported
225 entry->set_unqual_exported();
226 }
227 entry->set_module(module);
228 return entry;
229 }
230
231 void PackageEntryTable::add_entry(int index, PackageEntry* new_entry) {
232 assert(Module_lock->owned_by_self(), "should have the Module_lock");
233 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
234 }
235
236 // Create package in loader's package entry table and return the entry.
237 // If entry already exists, return null. Assume Module lock was taken by caller.
238 PackageEntry* PackageEntryTable::locked_create_entry_or_null(Symbol* name, ModuleEntry* module) {
239 assert(Module_lock->owned_by_self(), "should have the Module_lock");
240 // Check if package already exists. Return NULL if it does.
241 if (lookup_only(name) != NULL) {
242 return NULL;
243 } else {
244 PackageEntry* entry = new_entry(compute_hash(name), name, module);
245 add_entry(index_for(name), entry);
246 return entry;
247 }
248 }
249
250 PackageEntry* PackageEntryTable::lookup(Symbol* name, ModuleEntry* module) {
251 PackageEntry* p = lookup_only(name);
252 if (p != NULL) {
253 return p;
254 } else {
255 // If not found, add to table. Grab the PackageEntryTable lock first.
256 MutexLocker ml(Module_lock);
257
258 // Since look-up was done lock-free, we need to check if another thread beat
259 // us in the race to insert the package.
260 PackageEntry* test = lookup_only(name);
261 if (test != NULL) {
262 // A race occurred and another thread introduced the package.
263 return test;
264 } else {
265 assert(module != NULL, "module should never be null");
266 PackageEntry* entry = new_entry(compute_hash(name), name, module);
267 add_entry(index_for(name), entry);
268 return entry;
269 }
270 }
271 }
272
273 PackageEntry* PackageEntryTable::lookup_only(Symbol* name) {
274 int index = index_for(name);
275 for (PackageEntry* p = bucket(index); p != NULL; p = p->next()) {
276 if (p->name()->fast_compare(name) == 0) {
277 return p;
278 }
279 }
280 return NULL;
281 }
282
283 // Called when a define module for java.base is being processed.
284 // Verify the packages loaded thus far are in java.base's package list.
285 void PackageEntryTable::verify_javabase_packages(GrowableArray<Symbol*> *pkg_list) {
286 for (int i = 0; i < table_size(); i++) {
287 for (PackageEntry* entry = bucket(i);
288 entry != NULL;
289 entry = entry->next()) {
290 ModuleEntry* m = entry->module();
291 Symbol* module_name = (m == NULL ? NULL : m->name());
292 if (module_name != NULL &&
293 (module_name->fast_compare(vmSymbols::java_base()) == 0) &&
294 !pkg_list->contains(entry->name())) {
295 ResourceMark rm;
296 vm_exit_during_initialization("A non-java.base package was loaded prior to module system initialization", entry->name()->as_C_string());
297 }
298 }
299 }
300
301 }
302
303 // iteration of qualified exports
304 void PackageEntry::package_exports_do(ModuleClosure* const f) {
305 assert_locked_or_safepoint(Module_lock);
306 assert(f != NULL, "invariant");
307
308 if (has_qual_exports_list()) {
309 int qe_len = _qualified_exports->length();
310
311 for (int i = 0; i < qe_len; ++i) {
312 f->do_module(_qualified_exports->at(i));
313 }
314 }
315 }
316
317 // Remove dead entries from all packages' exported list
318 void PackageEntryTable::purge_all_package_exports() {
319 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
320 for (int i = 0; i < table_size(); i++) {
321 for (PackageEntry* entry = bucket(i);
322 entry != NULL;
323 entry = entry->next()) {
324 if (entry->exported_pending_delete()) {
325 // exported list is pending deletion due to a transition
326 // from qualified to unqualified
327 entry->delete_qualified_exports();
328 } else if (entry->is_qual_exported()) {
329 entry->purge_qualified_exports();
330 }
331 }
332 }
333 }
334
335 void PackageEntryTable::print(outputStream* st) {
336 st->print_cr("Package Entry Table (table_size=%d, entries=%d)",
337 table_size(), number_of_entries());
338 for (int i = 0; i < table_size(); i++) {
339 for (PackageEntry* probe = bucket(i);
340 probe != NULL;
341 probe = probe->next()) {
342 probe->print(st);
343 }
344 }
345 }
346
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, _is_exported_unqualified, _is_exported_allUnnamed, p2i(next()));
354 }
355
356 void PackageEntryTable::verify() {
357 int element_count = 0;
358 for (int index = 0; index < table_size(); index++) {
359 for (PackageEntry* probe = bucket(index);
360 probe != NULL;
361 probe = probe->next()) {
362 probe->verify();
363 element_count++;
364 }
365 }
366 guarantee(number_of_entries() == element_count,
367 "Verify of Package Entry Table failed");
368 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Package Entry Table"));
369 }
370
371 void PackageEntry::verify() {
372 guarantee(name() != NULL, "A package entry must have a corresponding symbol name.");
373 }