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 
 100   if (m == NULL) {
 101     // NULL indicates the package is being unqualifiedly exported.  Clean up
 102     // the qualified list at the next safepoint.
 103     set_unqual_exported();
 104   } else {
 105     // Add the exported module
 106     add_qexport(m);
 107   }
 108 }
 109 
 110 // Set the package as exported to all unnamed modules unless the package is
 111 // already unqualifiedly exported.
 112 void PackageEntry::set_is_exported_allUnnamed() {
 113   if (module()->is_open()) {
 114     // No-op for open modules since all packages are unqualifiedly exported
 115     return;
 116   }
 117 
 118   MutexLocker m1(Module_lock);
 119   if (!is_unqual_exported()) {
 120    _export_flags = PKG_EXP_ALLUNNAMED;
 121   }
 122 }
 123 
 124 // Remove dead module entries within the package's exported list.  Note that
 125 // if all of the modules on the _qualified_exports get purged the list does not
 126 // get deleted.  This prevents the package from illegally transitioning from
 127 // exported to non-exported.
 128 void PackageEntry::purge_qualified_exports() {
 129   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 130   if (_must_walk_exports &&
 131       _qualified_exports != NULL &&
 132       !_qualified_exports->is_empty()) {
 133     ModuleEntry* pkg_module = module();
 134 
 135     // This package's _must_walk_exports flag will be reset based
 136     // on the remaining live modules on the exports list.
 137     _must_walk_exports = false;
 138 
 139     if (log_is_enabled(Trace, modules)) {
 140       ResourceMark rm;
 141       assert(name() != NULL, "PackageEntry without a valid name");
 142       ModuleEntry* pkg_mod = module();
 143       log_trace(modules)("PackageEntry::purge_qualified_exports(): package %s defined in module %s, exports list being walked",
 144                          name()->as_C_string(),
 145                          (pkg_mod == NULL || pkg_mod->name() == NULL) ? UNNAMED_MODULE : pkg_mod->name()->as_C_string());
 146     }
 147 
 148     // Go backwards because this removes entries that are dead.
 149     int len = _qualified_exports->length();
 150     for (int idx = len - 1; idx >= 0; idx--) {
 151       ModuleEntry* module_idx = _qualified_exports->at(idx);
 152       ClassLoaderData* cld_idx = module_idx->loader_data();
 153       if (cld_idx->is_unloading()) {
 154         _qualified_exports->delete_at(idx);
 155       } else {
 156         // Update the need to walk this package's exports based on live modules
 157         set_export_walk_required(cld_idx);
 158       }
 159     }
 160   }
 161 }
 162 
 163 void PackageEntry::delete_qualified_exports() {
 164   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 165   if (_qualified_exports != NULL) {
 166     delete _qualified_exports;
 167   }
 168   _qualified_exports = NULL;
 169 }
 170 
 171 PackageEntryTable::PackageEntryTable(int table_size)
 172   : Hashtable<Symbol*, mtModule>(table_size, sizeof(PackageEntry))
 173 {
 174 }
 175 
 176 PackageEntryTable::~PackageEntryTable() {
 177   assert_locked_or_safepoint(Module_lock);
 178 
 179   // Walk through all buckets and all entries in each bucket,
 180   // freeing each entry.
 181   for (int i = 0; i < table_size(); ++i) {
 182     for (PackageEntry* p = bucket(i); p != NULL;) {
 183       PackageEntry* to_remove = p;
 184       // read next before freeing.
 185       p = p->next();
 186 
 187       // Clean out the C heap allocated qualified exports list first before freeing the entry
 188       to_remove->delete_qualified_exports();
 189       to_remove->name()->decrement_refcount();
 190 
 191       // Unlink from the Hashtable prior to freeing
 192       unlink_entry(to_remove);
 193       FREE_C_HEAP_ARRAY(char, to_remove);
 194     }
 195   }
 196   assert(number_of_entries() == 0, "should have removed all entries");
 197   assert(new_entry_free_list() == NULL, "entry present on PackageEntryTable's free list");
 198   free_buckets();
 199 }
 200 
 201 PackageEntry* PackageEntryTable::new_entry(unsigned int hash, Symbol* name, ModuleEntry* module) {
 202   assert(Module_lock->owned_by_self(), "should have the Module_lock");
 203   PackageEntry* entry = (PackageEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
 204 
 205   // Initialize everything BasicHashtable would
 206   entry->set_next(NULL);
 207   entry->set_hash(hash);
 208   entry->set_literal(name);
 209 
 210   TRACE_INIT_ID(entry);
 211 
 212   // Initialize fields specific to a PackageEntry
 213   entry->init();
 214   entry->name()->increment_refcount();
 215   entry->set_module(module);
 216   return entry;
 217 }
 218 
 219 void PackageEntryTable::add_entry(int index, PackageEntry* new_entry) {
 220   assert(Module_lock->owned_by_self(), "should have the Module_lock");
 221   Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
 222 }
 223 
 224 // Create package in loader's package entry table and return the entry.
 225 // If entry already exists, return null.  Assume Module lock was taken by caller.
 226 PackageEntry* PackageEntryTable::locked_create_entry_or_null(Symbol* name, ModuleEntry* module) {
 227   assert(Module_lock->owned_by_self(), "should have the Module_lock");
 228   // Check if package already exists.  Return NULL if it does.
 229   if (lookup_only(name) != NULL) {
 230     return NULL;
 231   } else {
 232     PackageEntry* entry = new_entry(compute_hash(name), name, module);
 233     add_entry(index_for(name), entry);
 234     return entry;
 235   }
 236 }
 237 
 238 PackageEntry* PackageEntryTable::lookup(Symbol* name, ModuleEntry* module) {
 239   PackageEntry* p = lookup_only(name);
 240   if (p != NULL) {
 241     return p;
 242   } else {
 243     // If not found, add to table. Grab the PackageEntryTable lock first.
 244     MutexLocker ml(Module_lock);
 245 
 246     // Since look-up was done lock-free, we need to check if another thread beat
 247     // us in the race to insert the package.
 248     PackageEntry* test = lookup_only(name);
 249     if (test != NULL) {
 250       // A race occurred and another thread introduced the package.
 251       return test;
 252     } else {
 253       assert(module != NULL, "module should never be null");
 254       PackageEntry* entry = new_entry(compute_hash(name), name, module);
 255       add_entry(index_for(name), entry);
 256       return entry;
 257     }
 258   }
 259 }
 260 
 261 PackageEntry* PackageEntryTable::lookup_only(Symbol* name) {
 262   int index = index_for(name);
 263   for (PackageEntry* p = bucket(index); p != NULL; p = p->next()) {
 264     if (p->name()->fast_compare(name) == 0) {
 265       return p;
 266     }
 267   }
 268   return NULL;
 269 }
 270 
 271 // Called when a define module for java.base is being processed.
 272 // Verify the packages loaded thus far are in java.base's package list.
 273 void PackageEntryTable::verify_javabase_packages(GrowableArray<Symbol*> *pkg_list) {
 274   for (int i = 0; i < table_size(); i++) {
 275     for (PackageEntry* entry = bucket(i);
 276                        entry != NULL;
 277                        entry = entry->next()) {
 278       ModuleEntry* m = entry->module();
 279       Symbol* module_name = (m == NULL ? NULL : m->name());
 280       if (module_name != NULL &&
 281           (module_name->fast_compare(vmSymbols::java_base()) == 0) &&
 282           !pkg_list->contains(entry->name())) {
 283         ResourceMark rm;
 284         vm_exit_during_initialization("A non-" JAVA_BASE_NAME " package was loaded prior to module system initialization", entry->name()->as_C_string());
 285       }
 286     }
 287   }
 288 
 289 }
 290 
 291 // iteration of qualified exports
 292 void PackageEntry::package_exports_do(ModuleClosure* const f) {
 293   assert_locked_or_safepoint(Module_lock);
 294   assert(f != NULL, "invariant");
 295 
 296   if (has_qual_exports_list()) {
 297     int qe_len = _qualified_exports->length();
 298 
 299     for (int i = 0; i < qe_len; ++i) {
 300       f->do_module(_qualified_exports->at(i));
 301     }
 302   }
 303 }
 304 
 305 bool PackageEntry::exported_pending_delete() const {
 306   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 307   return (is_unqual_exported() && _qualified_exports != NULL);
 308 }
 309 
 310 // Remove dead entries from all packages' exported list
 311 void PackageEntryTable::purge_all_package_exports() {
 312   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 313   for (int i = 0; i < table_size(); i++) {
 314     for (PackageEntry* entry = bucket(i);
 315                        entry != NULL;
 316                        entry = entry->next()) {
 317       if (entry->exported_pending_delete()) {
 318         // exported list is pending deletion due to a transition
 319         // from qualified to unqualified
 320         entry->delete_qualified_exports();
 321       } else if (entry->is_qual_exported()) {
 322         entry->purge_qualified_exports();
 323       }
 324     }
 325   }
 326 }
 327 
 328 void PackageEntryTable::print(outputStream* st) {
 329   st->print_cr("Package Entry Table (table_size=%d, entries=%d)",
 330                table_size(), number_of_entries());
 331   for (int i = 0; i < table_size(); i++) {
 332     for (PackageEntry* probe = bucket(i);
 333                        probe != NULL;
 334                        probe = probe->next()) {
 335       probe->print(st);
 336     }
 337   }
 338 }
 339 
 340 // This function may be called from debuggers so access private fields directly
 341 // to prevent triggering locking-related asserts that could result from calling
 342 // getter methods.
 343 void PackageEntry::print(outputStream* st) {
 344   ResourceMark rm;
 345   st->print_cr("package entry " PTR_FORMAT " name %s module %s classpath_index "
 346                INT32_FORMAT " is_exported_unqualified %d is_exported_allUnnamed %d " "next " PTR_FORMAT,
 347                p2i(this), name()->as_C_string(),
 348                (module()->is_named() ? module()->name()->as_C_string() : UNNAMED_MODULE),
 349                _classpath_index, _export_flags == PKG_EXP_UNQUALIFIED,
 350                _export_flags == PKG_EXP_ALLUNNAMED, p2i(next()));
 351 }
 352 
 353 void PackageEntryTable::verify() {
 354   int element_count = 0;
 355   for (int index = 0; index < table_size(); index++) {
 356     for (PackageEntry* probe = bucket(index);
 357                               probe != NULL;
 358                               probe = probe->next()) {
 359       probe->verify();
 360       element_count++;
 361     }
 362   }
 363   guarantee(number_of_entries() == element_count,
 364             "Verify of Package Entry Table failed");
 365   DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Package Entry Table"));
 366 }
 367 
 368 void PackageEntry::verify() {
 369   guarantee(name() != NULL, "A package entry must have a corresponding symbol name.");
 370 }