1 /*
   2  * Copyright (c) 2016, 2018, 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 "utilities/events.hpp"
  33 #include "utilities/growableArray.hpp"
  34 #include "utilities/hashtable.inline.hpp"
  35 #include "utilities/ostream.hpp"
  36 
  37 // Returns true if this package specifies m as a qualified export, including through an unnamed export
  38 bool PackageEntry::is_qexported_to(ModuleEntry* m) const {
  39   assert(Module_lock->owned_by_self(), "should have the Module_lock");
  40   assert(m != NULL, "No module to lookup in this package's qualified exports list");
  41   if (is_exported_allUnnamed() && !m->is_named()) {
  42     return true;
  43   } else if (!has_qual_exports_list()) {
  44     return false;
  45   } else {
  46     return _qualified_exports->contains(m);
  47   }
  48 }
  49 
  50 // Add a module to the package's qualified export list.
  51 void PackageEntry::add_qexport(ModuleEntry* m) {
  52   assert(Module_lock->owned_by_self(), "should have the Module_lock");
  53   if (!has_qual_exports_list()) {
  54     // Lazily create a package's qualified exports list.
  55     // Initial size is small, do not anticipate export lists to be large.
  56     _qualified_exports = new (ResourceObj::C_HEAP, mtModule) GrowableArray<ModuleEntry*>(QUAL_EXP_SIZE, true);
  57   }
  58 
  59   // Determine, based on this newly established export to module m,
  60   // if this package's export list should be walked at a GC safepoint.
  61   set_export_walk_required(m->loader_data());
  62 
  63   // Establish exportability to module m
  64   _qualified_exports->append_if_missing(m);
  65 }
  66 
  67 // If the module's loader, that an export is being established to, is
  68 // not the same loader as this module's and is not one of the 3 builtin
  69 // class loaders, then this package's export list must be walked at GC
  70 // safepoint. Modules have the same life cycle as their defining class
  71 // loaders and should be removed if dead.
  72 void PackageEntry::set_export_walk_required(ClassLoaderData* m_loader_data) {
  73   assert_locked_or_safepoint(Module_lock);
  74   ModuleEntry* this_pkg_mod = module();
  75   if (!_must_walk_exports &&
  76       (this_pkg_mod == NULL || this_pkg_mod->loader_data() != m_loader_data) &&
  77       !m_loader_data->is_builtin_class_loader_data()) {
  78     _must_walk_exports = true;
  79     if (log_is_enabled(Trace, module)) {
  80       ResourceMark rm;
  81       assert(name() != NULL, "PackageEntry without a valid name");
  82       log_trace(module)("PackageEntry::set_export_walk_required(): package %s defined in module %s, exports list must be walked",
  83                         name()->as_C_string(),
  84                         (this_pkg_mod == NULL || this_pkg_mod->name() == NULL) ?
  85                           UNNAMED_MODULE : this_pkg_mod->name()->as_C_string());
  86     }
  87   }
  88 }
  89 
  90 // Set the package's exported states based on the value of the ModuleEntry.
  91 void PackageEntry::set_exported(ModuleEntry* m) {
  92   MutexLocker m1(Module_lock);
  93   if (is_unqual_exported()) {
  94     // An exception could be thrown, but choose to simply ignore.
  95     // Illegal to convert an unqualified exported package to be qualifiedly exported
  96     return;
  97   }
  98 
  99   if (m == NULL) {
 100     // NULL indicates the package is being unqualifiedly exported.  Clean up
 101     // the qualified list at the next safepoint.
 102     set_unqual_exported();
 103   } else {
 104     // Add the exported module
 105     add_qexport(m);
 106   }
 107 }
 108 
 109 // Set the package as exported to all unnamed modules unless the package is
 110 // already unqualifiedly exported.
 111 void PackageEntry::set_is_exported_allUnnamed() {
 112   if (module()->is_open()) {
 113     // No-op for open modules since all packages are unqualifiedly exported
 114     return;
 115   }
 116 
 117   MutexLocker m1(Module_lock);
 118   if (!is_unqual_exported()) {
 119    _export_flags = PKG_EXP_ALLUNNAMED;
 120   }
 121 }
 122 
 123 // Remove dead module entries within the package's exported list.  Note that
 124 // if all of the modules on the _qualified_exports get purged the list does not
 125 // get deleted.  This prevents the package from illegally transitioning from
 126 // exported to non-exported.
 127 void PackageEntry::purge_qualified_exports() {
 128   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 129   if (_must_walk_exports &&
 130       _qualified_exports != NULL &&
 131       !_qualified_exports->is_empty()) {
 132     ModuleEntry* pkg_module = module();
 133 
 134     // This package's _must_walk_exports flag will be reset based
 135     // on the remaining live modules on the exports list.
 136     _must_walk_exports = false;
 137 
 138     if (log_is_enabled(Trace, module)) {
 139       ResourceMark rm;
 140       assert(name() != NULL, "PackageEntry without a valid name");
 141       ModuleEntry* pkg_mod = module();
 142       log_trace(module)("PackageEntry::purge_qualified_exports(): package %s defined in module %s, exports list being walked",
 143                         name()->as_C_string(),
 144                         (pkg_mod == NULL || pkg_mod->name() == NULL) ? UNNAMED_MODULE : pkg_mod->name()->as_C_string());
 145     }
 146 
 147     // Go backwards because this removes entries that are dead.
 148     int len = _qualified_exports->length();
 149     for (int idx = len - 1; idx >= 0; idx--) {
 150       ModuleEntry* module_idx = _qualified_exports->at(idx);
 151       ClassLoaderData* cld_idx = module_idx->loader_data();
 152       if (cld_idx->is_unloading()) {
 153         _qualified_exports->delete_at(idx);
 154       } else {
 155         // Update the need to walk this package's exports based on live modules
 156         set_export_walk_required(cld_idx);
 157       }
 158     }
 159   }
 160 }
 161 
 162 void PackageEntry::delete_qualified_exports() {
 163   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 164   if (_qualified_exports != NULL) {
 165     delete _qualified_exports;
 166   }
 167   _qualified_exports = NULL;
 168 }
 169 
 170 PackageEntryTable::PackageEntryTable(int table_size)
 171   : Hashtable<Symbol*, mtModule>(table_size, sizeof(PackageEntry))
 172 {
 173 }
 174 
 175 PackageEntryTable::~PackageEntryTable() {
 176   // Walk through all buckets and all entries in each bucket,
 177   // freeing each entry.
 178   for (int i = 0; i < table_size(); ++i) {
 179     for (PackageEntry* p = bucket(i); p != NULL;) {
 180       PackageEntry* to_remove = p;
 181       // read next before freeing.
 182       p = p->next();
 183 
 184       // Clean out the C heap allocated qualified exports list first before freeing the entry
 185       to_remove->delete_qualified_exports();
 186       to_remove->name()->decrement_refcount();
 187 
 188       // Unlink from the Hashtable prior to freeing
 189       unlink_entry(to_remove);
 190       FREE_C_HEAP_ARRAY(char, to_remove);
 191     }
 192   }
 193   assert(number_of_entries() == 0, "should have removed all entries");
 194   assert(new_entry_free_list() == NULL, "entry present on PackageEntryTable's free list");
 195   free_buckets();
 196 }
 197 
 198 PackageEntry* PackageEntryTable::new_entry(unsigned int hash, Symbol* name, ModuleEntry* module) {
 199   assert(Module_lock->owned_by_self(), "should have the Module_lock");
 200   PackageEntry* entry = (PackageEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name);
 201 
 202   JFR_ONLY(INIT_ID(entry);)
 203 
 204   // Initialize fields specific to a PackageEntry
 205   entry->init();
 206   entry->name()->increment_refcount();
 207   entry->set_module(module);
 208   return entry;
 209 }
 210 
 211 void PackageEntryTable::add_entry(int index, PackageEntry* new_entry) {
 212   assert(Module_lock->owned_by_self(), "should have the Module_lock");
 213   Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
 214 }
 215 
 216 // Create package in loader's package entry table and return the entry.
 217 // If entry already exists, return null.  Assume Module lock was taken by caller.
 218 PackageEntry* PackageEntryTable::locked_create_entry_or_null(Symbol* name, ModuleEntry* module) {
 219   assert(Module_lock->owned_by_self(), "should have the Module_lock");
 220   // Check if package already exists.  Return NULL if it does.
 221   if (lookup_only(name) != NULL) {
 222     return NULL;
 223   } else {
 224     PackageEntry* entry = new_entry(compute_hash(name), name, module);
 225     add_entry(index_for(name), entry);
 226     return entry;
 227   }
 228 }
 229 
 230 PackageEntry* PackageEntryTable::lookup(Symbol* name, ModuleEntry* module) {

 231   PackageEntry* p = lookup_only(name);
 232   if (p != NULL) {
 233     return p;
 234   } else {
 235     // If not found, add to table. Grab the PackageEntryTable lock first.
 236     MutexLocker ml(Module_lock);
 237 
 238     // Since look-up was done lock-free, we need to check if another thread beat
 239     // us in the race to insert the package.
 240     PackageEntry* test = lookup_only(name);
 241     if (test != NULL) {
 242       // A race occurred and another thread introduced the package.
 243       return test;
 244     } else {
 245       assert(module != NULL, "module should never be null");
 246       PackageEntry* entry = new_entry(compute_hash(name), name, module);
 247       add_entry(index_for(name), entry);
 248       return entry;
 249     }
 250   }
 251 }
 252 
 253 PackageEntry* PackageEntryTable::lookup_only(Symbol* name) {

 254   int index = index_for(name);
 255   for (PackageEntry* p = bucket(index); p != NULL; p = p->next()) {
 256     if (p->name()->fast_compare(name) == 0) {
 257       return p;
 258     }
 259   }
 260   return NULL;
 261 }
 262 
 263 // Called when a define module for java.base is being processed.
 264 // Verify the packages loaded thus far are in java.base's package list.
 265 void PackageEntryTable::verify_javabase_packages(GrowableArray<Symbol*> *pkg_list) {
 266   assert_lock_strong(Module_lock);
 267   for (int i = 0; i < table_size(); i++) {
 268     for (PackageEntry* entry = bucket(i);
 269                        entry != NULL;
 270                        entry = entry->next()) {
 271       ModuleEntry* m = entry->module();
 272       Symbol* module_name = (m == NULL ? NULL : m->name());
 273       if (module_name != NULL &&
 274           (module_name->fast_compare(vmSymbols::java_base()) == 0) &&
 275           !pkg_list->contains(entry->name())) {
 276         ResourceMark rm;
 277         vm_exit_during_initialization("A non-" JAVA_BASE_NAME " package was loaded prior to module system initialization", entry->name()->as_C_string());
 278       }
 279     }
 280   }
 281 
 282 }
 283 
 284 // iteration of qualified exports
 285 void PackageEntry::package_exports_do(ModuleClosure* f) {
 286   assert_locked_or_safepoint(Module_lock);
 287   assert(f != NULL, "invariant");
 288 
 289   if (has_qual_exports_list()) {
 290     int qe_len = _qualified_exports->length();
 291 
 292     for (int i = 0; i < qe_len; ++i) {
 293       f->do_module(_qualified_exports->at(i));
 294     }
 295   }
 296 }
 297 
 298 bool PackageEntry::exported_pending_delete() const {
 299   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 300   return (is_unqual_exported() && _qualified_exports != NULL);
 301 }
 302 
 303 // Remove dead entries from all packages' exported list
 304 void PackageEntryTable::purge_all_package_exports() {
 305   assert_locked_or_safepoint(Module_lock);
 306   for (int i = 0; i < table_size(); i++) {
 307     for (PackageEntry* entry = bucket(i);
 308                        entry != NULL;
 309                        entry = entry->next()) {
 310       if (entry->exported_pending_delete()) {
 311         // exported list is pending deletion due to a transition
 312         // from qualified to unqualified
 313         entry->delete_qualified_exports();
 314       } else if (entry->is_qual_exported()) {
 315         entry->purge_qualified_exports();
 316       }
 317     }
 318   }
 319 }
 320 
 321 void PackageEntryTable::print(outputStream* st) {
 322   st->print_cr("Package Entry Table (table_size=%d, entries=%d)",
 323                table_size(), number_of_entries());
 324   for (int i = 0; i < table_size(); i++) {
 325     for (PackageEntry* probe = bucket(i);
 326                        probe != NULL;
 327                        probe = probe->next()) {
 328       probe->print(st);
 329     }
 330   }
 331 }
 332 
 333 // This function may be called from debuggers so access private fields directly
 334 // to prevent triggering locking-related asserts that could result from calling
 335 // getter methods.
 336 void PackageEntry::print(outputStream* st) {
 337   ResourceMark rm;
 338   st->print_cr("package entry " PTR_FORMAT " name %s module %s classpath_index "
 339                INT32_FORMAT " is_exported_unqualified %d is_exported_allUnnamed %d " "next " PTR_FORMAT,
 340                p2i(this), name()->as_C_string(),
 341                (module()->is_named() ? module()->name()->as_C_string() : UNNAMED_MODULE),
 342                _classpath_index, _export_flags == PKG_EXP_UNQUALIFIED,
 343                _export_flags == PKG_EXP_ALLUNNAMED, p2i(next()));
 344 }
 345 
 346 void PackageEntryTable::verify() {
 347   verify_table<PackageEntry>("Package Entry Table");
 348 }
 349 
 350 void PackageEntry::verify() {
 351   guarantee(name() != NULL, "A package entry must have a corresponding symbol name.");
 352 }
--- EOF ---