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
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  23  */
  24 
  25 #ifndef SHARE_VM_CLASSFILE_PACKAGEENTRY_HPP
  26 #define SHARE_VM_CLASSFILE_PACKAGEENTRY_HPP
  27 
  28 #include "classfile/moduleEntry.hpp"
  29 #include "oops/symbol.hpp"
  30 #include "utilities/growableArray.hpp"
  31 #include "utilities/hashtable.hpp"
  32 #include "utilities/macros.hpp"
  33 #include "utilities/ostream.hpp"
  34 #if INCLUDE_JFR
  35 #include "jfr/support/jfrTraceIdExtension.hpp"
  36 #endif
  37 
  38 
  39 // A PackageEntry basically represents a Java package.  It contains:
  40 //   - Symbol* containing the package's name.
  41 //   - ModuleEntry* for this package's containing module.
  42 //   - a field indicating if the package is exported unqualifiedly or to all
  43 //     unnamed modules.
  44 //   - a growable array containing other module entries that this
  45 //     package is exported to.
  46 //
  47 // Packages can be exported in the following 3 ways:
  48 //   - not exported:        the package does not have qualified or unqualified exports.
  49 //   - qualified exports:   the package has been explicitly qualified to at least
  50 //                            one particular module or has been qualifiedly exported
  51 //                            to all unnamed modules.
  52 //                            Note: being exported to all unnamed is a form of a qualified
  53 //                            export. It is equivalent to the package being explicitly
  54 //                            exported to all current and future unnamed modules.
  55 //   - unqualified exports: the package is exported to all modules.
  56 //
  57 // A package can transition from:
  58 //   - being not exported, to being exported either in a qualified or unqualified manner
  59 //   - being qualifiedly exported, to unqualifiedly exported. Its exported scope is widened.
  60 //
  61 // A package cannot transition from:
  62 //   - being unqualifiedly exported, to exported qualifiedly to a specific module.
  63 //       This transition attempt is silently ignored in set_exported.
  64 //   - being qualifiedly exported to not exported.
  65 //       Because transitions are only allowed from less exposure to greater exposure,
  66 //       the transition from qualifiedly exported to not exported would be considered
  67 //       a backward direction.  Therefore the implementation considers a package as
  68 //       qualifiedly exported even if its export-list exists but is empty.
  69 //
  70 // The Mutex Module_lock is shared between ModuleEntry and PackageEntry, to lock either
  71 // data structure.
  72 
  73 // PKG_EXP_UNQUALIFIED and PKG_EXP_ALLUNNAMED indicate whether the package is
  74 // exported unqualifiedly or exported to all unnamed modules.  They are used to
  75 // set the value of _export_flags.  Field _export_flags and the _qualified_exports
  76 // list are used to determine a package's export state.
  77 // Valid states are:
  78 //
  79 //   1. Package is not exported
  80 //      _export_flags is zero and _qualified_exports is null
  81 //   2. Package is unqualifiedly exported
  82 //      _export_flags is set to PKG_EXP_UNQUALIFIED
  83 //      _qualified_exports may or may not be null depending on whether the package
  84 //        transitioned from qualifiedly exported to unqualifiedly exported.
  85 //   3. Package is qualifiedly exported
  86 //      _export_flags may be set to PKG_EXP_ALLUNNAMED if the package is also
  87 //        exported to all unnamed modules
  88 //      _qualified_exports will be non-null
  89 //   4. Package is exported to all unnamed modules
  90 //      _export_flags is set to PKG_EXP_ALLUNNAMED
  91 //      _qualified_exports may or may not be null depending on whether the package
  92 //        is also qualifiedly exported to one or more named modules.
  93 #define PKG_EXP_UNQUALIFIED  0x0001
  94 #define PKG_EXP_ALLUNNAMED   0x0002
  95 #define PKG_EXP_UNQUALIFIED_OR_ALL_UNAMED (PKG_EXP_UNQUALIFIED | PKG_EXP_ALLUNNAMED)
  96 
  97 class PackageEntry : public HashtableEntry<Symbol*, mtModule> {
  98 private:
  99   ModuleEntry* _module;
 100   // Indicates if package is exported unqualifiedly or to all unnamed. Access to
 101   // this field is protected by the Module_lock.
 102   int _export_flags;
 103   // Used to indicate for packages with classes loaded by the boot loader that
 104   // a class in that package has been loaded.  And, for packages with classes
 105   // loaded by the boot loader from -Xbootclasspath/a in an unnamed module, it
 106   // indicates from which class path entry.
 107   s2 _classpath_index;
 108   bool _must_walk_exports;
 109   // Contains list of modules this package is qualifiedly exported to.  Access
 110   // to this list is protected by the Module_lock.
 111   GrowableArray<ModuleEntry*>* _qualified_exports;
 112   JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
 113 
 114   // Initial size of a package entry's list of qualified exports.
 115   enum {QUAL_EXP_SIZE = 43};
 116 
 117 public:
 118   void init() {
 119     _module = NULL;
 120     _export_flags = 0;
 121     _classpath_index = -1;
 122     _must_walk_exports = false;
 123     _qualified_exports = NULL;
 124   }
 125 
 126   // package name
 127   Symbol*            name() const               { return literal(); }
 128 
 129   // the module containing the package definition
 130   ModuleEntry*       module() const             { return _module; }
 131   void               set_module(ModuleEntry* m) { _module = m; }
 132 
 133   // package's export state
 134   bool is_exported() const { // qualifiedly or unqualifiedly exported
 135     assert_locked_or_safepoint(Module_lock);
 136     return module()->is_open() ||
 137             ((_export_flags & PKG_EXP_UNQUALIFIED_OR_ALL_UNAMED) != 0) ||
 138             has_qual_exports_list();
 139   }
 140   // Returns true if the package has any explicit qualified exports or is exported to all unnamed
 141   bool is_qual_exported() const {
 142     assert_locked_or_safepoint(Module_lock);
 143     return (has_qual_exports_list() || is_exported_allUnnamed());
 144   }
 145   // Returns true if there are any explicit qualified exports.  Note that even
 146   // if the _qualified_exports list is now empty (because the modules that were
 147   // on the list got gc-ed and deleted from the list) this method may still
 148   // return true.
 149   bool has_qual_exports_list() const {
 150     assert_locked_or_safepoint(Module_lock);
 151     return (!is_unqual_exported() && _qualified_exports != NULL);
 152   }
 153   bool is_exported_allUnnamed() const {
 154     assert_locked_or_safepoint(Module_lock);
 155     return (module()->is_open() || _export_flags == PKG_EXP_ALLUNNAMED);
 156   }
 157   bool is_unqual_exported() const {
 158     assert_locked_or_safepoint(Module_lock);
 159     return (module()->is_open() || _export_flags == PKG_EXP_UNQUALIFIED);
 160   }
 161 
 162   // Explicitly set _export_flags to PKG_EXP_UNQUALIFIED and clear
 163   // PKG_EXP_ALLUNNAMED, if it was set.
 164   void set_unqual_exported() {
 165     if (module()->is_open()) {
 166         // No-op for open modules since all packages are unqualifiedly exported
 167         return;
 168     }
 169     assert(Module_lock->owned_by_self(), "should have the Module_lock");
 170     _export_flags = PKG_EXP_UNQUALIFIED;
 171   }
 172 
 173   bool exported_pending_delete() const;
 174 
 175   void set_exported(ModuleEntry* m);
 176 
 177   void set_is_exported_allUnnamed();
 178 
 179   void set_classpath_index(s2 classpath_index) {
 180     _classpath_index = classpath_index;
 181   }
 182   s2 classpath_index() const { return _classpath_index; }
 183 
 184   bool has_loaded_class() const { return _classpath_index != -1; }
 185 
 186   // returns true if the package is defined in the unnamed module
 187   bool in_unnamed_module() const  { return !_module->is_named(); }
 188 
 189   // returns true if the package specifies m as a qualified export, including through an unnamed export
 190   bool is_qexported_to(ModuleEntry* m) const;
 191 
 192   // add the module to the package's qualified exports
 193   void add_qexport(ModuleEntry* m);
 194   void set_export_walk_required(ClassLoaderData* m_loader_data);
 195 
 196   PackageEntry* next() const {
 197     return (PackageEntry*)HashtableEntry<Symbol*, mtModule>::next();
 198   }
 199 
 200   PackageEntry** next_addr() {
 201     return (PackageEntry**)HashtableEntry<Symbol*, mtModule>::next_addr();
 202   }
 203 
 204   // iteration of qualified exports
 205   void package_exports_do(ModuleClosure* f);
 206 
 207   JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
 208 
 209   // Purge dead weak references out of exported list when any given class loader is unloaded.
 210   void purge_qualified_exports();
 211   void delete_qualified_exports();
 212 
 213   void print(outputStream* st = tty);
 214   void verify();
 215 };
 216 
 217 // The PackageEntryTable is a Hashtable containing a list of all packages defined
 218 // by a particular class loader.  Each package is represented as a PackageEntry node.
 219 // The PackageEntryTable's lookup is lock free.
 220 //
 221 class PackageEntryTable : public Hashtable<Symbol*, mtModule> {
 222   friend class VMStructs;
 223 public:
 224   enum Constants {
 225     _packagetable_entry_size = 109  // number of entries in package entry table
 226   };
 227 
 228 private:
 229   PackageEntry* new_entry(unsigned int hash, Symbol* name, ModuleEntry* module);
 230   void add_entry(int index, PackageEntry* new_entry);
 231 
 232   int entry_size() const { return BasicHashtable<mtModule>::entry_size(); }
 233 
 234   PackageEntry** bucket_addr(int i) {
 235     return (PackageEntry**)Hashtable<Symbol*, mtModule>::bucket_addr(i);
 236   }
 237 
 238   static unsigned int compute_hash(Symbol* name) { return (unsigned int)(name->identity_hash()); }
 239   int index_for(Symbol* name) const { return hash_to_index(compute_hash(name)); }
 240 
 241 public:
 242   PackageEntryTable(int table_size);
 243   ~PackageEntryTable();
 244 
 245   PackageEntry* bucket(int i) {
 246     return (PackageEntry*)Hashtable<Symbol*, mtModule>::bucket(i);
 247   }
 248 
 249   // Create package in loader's package entry table and return the entry.
 250   // If entry already exists, return null.  Assume Module lock was taken by caller.
 251   PackageEntry* locked_create_entry_or_null(Symbol* name, ModuleEntry* module);
 252 
 253   // lookup Package with loader's package entry table, if not found add
 254   PackageEntry* lookup(Symbol* name, ModuleEntry* module);
 255 
 256   // Only lookup Package within loader's package entry table.
 257   PackageEntry* lookup_only(Symbol* Package);
 258 
 259   void verify_javabase_packages(GrowableArray<Symbol*> *pkg_list);
 260 
 261   // purge dead weak references out of exported list
 262   void purge_all_package_exports();
 263 
 264   void print(outputStream* st = tty);
 265   void verify();
 266 };
 267 
 268 #endif // SHARE_VM_CLASSFILE_PACKAGEENTRY_HPP
--- EOF ---