/*

 * Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

#ifndef SHARE_VM_CLASSFILE_PACKAGEENTRY_HPP

#define SHARE_VM_CLASSFILE_PACKAGEENTRY_HPP

#include "classfile/moduleEntry.hpp"

#include "oops/symbol.hpp"

#include "utilities/growableArray.hpp"

#include "utilities/hashtable.hpp"

#include "utilities/ostream.hpp"

// A PackageEntry basically represents a Java package.  It contains:

//   - Symbol* containing the package's name.

//   - ModuleEntry* for this package's containing module.

//   - a field indicating if the package is exported unqualifiedly or to all

//     unnamed modules.

//   - a growable array containing other module entries that this

//     package is exported to.

//

// Packages can be exported in the following 3 ways:

//   - not exported:        the package does not have qualified or unqualified exports.

//   - qualified exports:   the package has been explicitly qualified to at least

//                            one particular module or has been qualifiedly exported

//                            to all unnamed modules.

//                            Note: being exported to all unnamed is a form of a qualified

//                            export. It is equivalent to the package being explicitly

//                            exported to all current and future unnamed modules.

//   - unqualified exports: the package is exported to all modules.

//

// A package can transition from:

//   - being not exported, to being exported either in a qualified or unqualified manner

//   - being qualifiedly exported, to unqualifiedly exported. Its exported scope is widened.

//

// A package cannot transition from:

//   - being unqualifiedly exported, to exported qualifiedly to a specific module.

//       This transition attempt is silently ignored in set_exported.

//   - being qualifiedly exported to not exported.

//       Because transitions are only allowed from less exposure to greater exposure,

//       the transition from qualifiedly exported to not exported would be considered

//       a backward direction.  Therefore the implementation considers a package as

//       qualifiedly exported even if its export-list exists but is empty.

//

// The Mutex Module_lock is shared between ModuleEntry and PackageEntry, to lock either

// data structure.

// PKG_EXP_UNQUALIFIED and PKG_EXP_ALLUNNAMED indicate whether the package is

// exported unqualifiedly or exported to all unnamed modules.  They are used to

// set the value of _export_flags.  Field _export_flags and the _qualified_exports

// list are used to determine a package's export state.

// Valid states are:

//

//   1. Package is not exported

//      _export_flags is zero and _qualified_exports is null

//   2. Package is unqualifiedly exported

//      _export_flags is set to PKG_EXP_UNQUALIFIED

//      _qualified_exports may or may not be null depending on whether the package

//        transitioned from qualifiedly exported to unqualifiedly exported.

//   3. Package is qualifiedly exported

//      _export_flags may be set to PKG_EXP_ALLUNNAMED if the package is also

//        exported to all unnamed modules

//      _qualified_exports will be non-null

//   4. Package is exported to all unnamed modules

//      _export_flags is set to PKG_EXP_ALLUNNAMED

//      _qualified_exports may or may not be null depending on whether the package

//        is also qualifiedly exported to one or more named modules.

#define PKG_EXP_UNQUALIFIED  0x0001

#define PKG_EXP_ALLUNNAMED   0x0002

#define PKG_EXP_UNQUALIFIED_OR_ALL_UNAMED (PKG_EXP_UNQUALIFIED | PKG_EXP_ALLUNNAMED)

class PackageEntry : public HashtableEntry<Symbol*, mtModule> {

private:

  ModuleEntry* _module;

  // Indicates if package is exported unqualifiedly or to all unnamed. Access to

  // this field is protected by the Module_lock.

  int _export_flags;

  // Used to indicate for packages with classes loaded by the boot loader that

  // a class in that package has been loaded.  And, for packages with classes

  // loaded by the boot loader from -Xbootclasspath/a in an unnamed module, it

  // indicates from which class path entry.

  s2 _classpath_index;

  bool _must_walk_exports;

  // Contains list of modules this package is qualifiedly exported to.  Access

  // to this list is protected by the Module_lock.

  GrowableArray<ModuleEntry*>* _qualified_exports;

  // Initial size of a package entry's list of qualified exports.

  enum {QUAL_EXP_SIZE = 43};

public:

  void init() {

    _module = NULL;

    _export_flags = 0;

    _classpath_index = -1;

    _must_walk_exports = false;

    _qualified_exports = NULL;

  }

  // package name

  Symbol*            name() const               { return literal(); }

  // the module containing the package definition

  ModuleEntry*       module() const             { return _module; }

  void               set_module(ModuleEntry* m) { _module = m; }

  // package's export state

  bool is_exported() const { // qualifiedly or unqualifiedly exported

    assert_locked_or_safepoint(Module_lock);

    return module()->is_open() ||

            ((_export_flags & PKG_EXP_UNQUALIFIED_OR_ALL_UNAMED) != 0) ||

            has_qual_exports_list();

  }

  // Returns true if the package has any explicit qualified exports or is exported to all unnamed

  bool is_qual_exported() const {

    assert_locked_or_safepoint(Module_lock);

    return (has_qual_exports_list() || is_exported_allUnnamed());

  }

  // Returns true if there are any explicit qualified exports.  Note that even

  // if the _qualified_exports list is now empty (because the modules that were

  // on the list got gc-ed and deleted from the list) this method may still

  // return true.

  bool has_qual_exports_list() const {

    assert_locked_or_safepoint(Module_lock);

    return (!is_unqual_exported() && _qualified_exports != NULL);

  }

  bool is_exported_allUnnamed() const {

    assert_locked_or_safepoint(Module_lock);

    return (module()->is_open() || _export_flags == PKG_EXP_ALLUNNAMED);

  }

  bool is_unqual_exported() const {

    assert_locked_or_safepoint(Module_lock);

    return (module()->is_open() || _export_flags == PKG_EXP_UNQUALIFIED);

  }

  // Explicitly set _export_flags to PKG_EXP_UNQUALIFIED and clear

  // PKG_EXP_ALLUNNAMED, if it was set.

  void set_unqual_exported() {

    if (module()->is_open()) {

        // No-op for open modules since all packages are unqualifiedly exported

        return;

    }

    assert(Module_lock->owned_by_self(), "should have the Module_lock");

    _export_flags = PKG_EXP_UNQUALIFIED;

  }

  bool exported_pending_delete() const;

  void set_exported(ModuleEntry* m);

  void set_is_exported_allUnnamed();

  void set_classpath_index(s2 classpath_index) {

    _classpath_index = classpath_index;

  }

  s2 classpath_index() const { return _classpath_index; }

  bool has_loaded_class() const { return _classpath_index != -1; }

  // returns true if the package is defined in the unnamed module

  bool in_unnamed_module() const  { return !_module->is_named(); }

  // returns true if the package specifies m as a qualified export, including through an unnamed export

  bool is_qexported_to(ModuleEntry* m) const;

  // add the module to the package's qualified exports

  void add_qexport(ModuleEntry* m);

  void set_export_walk_required(ClassLoaderData* m_loader_data);

  PackageEntry* next() const {

    return (PackageEntry*)HashtableEntry<Symbol*, mtModule>::next();

  }

  PackageEntry** next_addr() {

    return (PackageEntry**)HashtableEntry<Symbol*, mtModule>::next_addr();

  }

  // iteration of qualified exports

  // Purge dead weak references out of exported list when any given class loader is unloaded.

  void purge_qualified_exports();

  void delete_qualified_exports();

  void print(outputStream* st = tty);

  void verify();

};

// The PackageEntryTable is a Hashtable containing a list of all packages defined

// by a particular class loader.  Each package is represented as a PackageEntry node.

// The PackageEntryTable's lookup is lock free.

//

class PackageEntryTable : public Hashtable<Symbol*, mtModule> {

  friend class VMStructs;

public:

  enum Constants {

    _packagetable_entry_size = 109  // number of entries in package entry table

  };

private:

  PackageEntry* new_entry(unsigned int hash, Symbol* name, ModuleEntry* module);

  void add_entry(int index, PackageEntry* new_entry);

  int entry_size() const { return BasicHashtable<mtModule>::entry_size(); }

  PackageEntry** bucket_addr(int i) {

    return (PackageEntry**)Hashtable<Symbol*, mtModule>::bucket_addr(i);

  }

  static unsigned int compute_hash(Symbol* name) { return (unsigned int)(name->identity_hash()); }

  int index_for(Symbol* name) const { return hash_to_index(compute_hash(name)); }

public:

  PackageEntryTable(int table_size);

  ~PackageEntryTable();

  PackageEntry* bucket(int i) {

    return (PackageEntry*)Hashtable<Symbol*, mtModule>::bucket(i);

  }

  // Create package in loader's package entry table and return the entry.

  // If entry already exists, return null.  Assume Module lock was taken by caller.

  PackageEntry* locked_create_entry_or_null(Symbol* name, ModuleEntry* module);

  // lookup Package with loader's package entry table, if not found add

  PackageEntry* lookup(Symbol* name, ModuleEntry* module);

  // Only lookup Package within loader's package entry table.  The table read is lock-free.

  PackageEntry* lookup_only(Symbol* Package);

  void verify_javabase_packages(GrowableArray<Symbol*> *pkg_list);

  // purge dead weak references out of exported list

  void purge_all_package_exports();

  void print(outputStream* st = tty);

  void verify();

};

#endif // SHARE_VM_CLASSFILE_PACKAGEENTRY_HPP