/*

 * Copyright (c) 2016, 2018, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "classfile/moduleEntry.hpp"

#include "classfile/packageEntry.hpp"

#include "logging/log.hpp"

#include "memory/resourceArea.hpp"

#include "oops/symbol.hpp"

#include "runtime/handles.inline.hpp"

#include "utilities/events.hpp"

#include "utilities/growableArray.hpp"

#include "utilities/hashtable.inline.hpp"

#include "utilities/ostream.hpp"

// Returns true if this package specifies m as a qualified export, including through an unnamed export

bool PackageEntry::is_qexported_to(ModuleEntry* m) const {

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

  assert(m != NULL, "No module to lookup in this package's qualified exports list");

  if (is_exported_allUnnamed() && !m->is_named()) {

    return true;

  } else if (!has_qual_exports_list()) {

    return false;

  } else {

    return _qualified_exports->contains(m);

  }

}

// Add a module to the package's qualified export list.

void PackageEntry::add_qexport(ModuleEntry* m) {

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

  if (!has_qual_exports_list()) {

    // Lazily create a package's qualified exports list.

    // Initial size is small, do not anticipate export lists to be large.

    _qualified_exports = new (ResourceObj::C_HEAP, mtModule) GrowableArray<ModuleEntry*>(QUAL_EXP_SIZE, true);

  }

  // Determine, based on this newly established export to module m,

  // if this package's export list should be walked at a GC safepoint.

  set_export_walk_required(m->loader_data());

  // Establish exportability to module m

  _qualified_exports->append_if_missing(m);

}

// If the module's loader, that an export is being established to, is

// not the same loader as this module's and is not one of the 3 builtin

// class loaders, then this package's export list must be walked at GC

// safepoint. Modules have the same life cycle as their defining class

// loaders and should be removed if dead.

void PackageEntry::set_export_walk_required(ClassLoaderData* m_loader_data) {

  assert_locked_or_safepoint(Module_lock);

  ModuleEntry* this_pkg_mod = module();

  if (!_must_walk_exports &&

      (this_pkg_mod == NULL || this_pkg_mod->loader_data() != m_loader_data) &&

      !m_loader_data->is_builtin_class_loader_data()) {

    _must_walk_exports = true;

    if (log_is_enabled(Trace, module)) {

      ResourceMark rm;

      assert(name() != NULL, "PackageEntry without a valid name");

      log_trace(module)("PackageEntry::set_export_walk_required(): package %s defined in module %s, exports list must be walked",

                        name()->as_C_string(),

                        (this_pkg_mod == NULL || this_pkg_mod->name() == NULL) ?

                          UNNAMED_MODULE : this_pkg_mod->name()->as_C_string());

    }

  }

}

// Set the package's exported states based on the value of the ModuleEntry.

void PackageEntry::set_exported(ModuleEntry* m) {

  MutexLocker m1(Module_lock);

  if (is_unqual_exported()) {

    // An exception could be thrown, but choose to simply ignore.

    // Illegal to convert an unqualified exported package to be qualifiedly exported

    return;

  }

  if (m == NULL) {

    // NULL indicates the package is being unqualifiedly exported.  Clean up

    // the qualified list at the next safepoint.

    set_unqual_exported();

  } else {

    // Add the exported module

    add_qexport(m);

  }

}

// Set the package as exported to all unnamed modules unless the package is

// already unqualifiedly exported.

void PackageEntry::set_is_exported_allUnnamed() {

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

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

    return;

  }

  MutexLocker m1(Module_lock);

  if (!is_unqual_exported()) {

   _export_flags = PKG_EXP_ALLUNNAMED;

  }

}

// Remove dead module entries within the package's exported list.  Note that

// if all of the modules on the _qualified_exports get purged the list does not

// get deleted.  This prevents the package from illegally transitioning from

// exported to non-exported.

void PackageEntry::purge_qualified_exports() {

  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");

  if (_must_walk_exports &&

      _qualified_exports != NULL &&

      !_qualified_exports->is_empty()) {

    ModuleEntry* pkg_module = module();

    // This package's _must_walk_exports flag will be reset based

    // on the remaining live modules on the exports list.

    _must_walk_exports = false;

    if (log_is_enabled(Trace, module)) {

      ResourceMark rm;

      assert(name() != NULL, "PackageEntry without a valid name");

      ModuleEntry* pkg_mod = module();

      log_trace(module)("PackageEntry::purge_qualified_exports(): package %s defined in module %s, exports list being walked",

                        name()->as_C_string(),

                        (pkg_mod == NULL || pkg_mod->name() == NULL) ? UNNAMED_MODULE : pkg_mod->name()->as_C_string());

    }

    // Go backwards because this removes entries that are dead.

    int len = _qualified_exports->length();

    for (int idx = len - 1; idx >= 0; idx--) {

      ModuleEntry* module_idx = _qualified_exports->at(idx);

      ClassLoaderData* cld_idx = module_idx->loader_data();

      if (cld_idx->is_unloading()) {

        _qualified_exports->delete_at(idx);

      } else {

        // Update the need to walk this package's exports based on live modules

        set_export_walk_required(cld_idx);

      }

    }

  }

}

void PackageEntry::delete_qualified_exports() {

  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");

  if (_qualified_exports != NULL) {

    delete _qualified_exports;

  }

  _qualified_exports = NULL;

}

PackageEntryTable::PackageEntryTable(int table_size)

  : Hashtable<Symbol*, mtModule>(table_size, sizeof(PackageEntry))

{

}

PackageEntryTable::~PackageEntryTable() {

  // Walk through all buckets and all entries in each bucket,

  // freeing each entry.

  for (int i = 0; i < table_size(); ++i) {

    for (PackageEntry* p = bucket(i); p != NULL;) {

      PackageEntry* to_remove = p;

      // read next before freeing.

      p = p->next();

      // Clean out the C heap allocated qualified exports list first before freeing the entry

      to_remove->delete_qualified_exports();

      to_remove->name()->decrement_refcount();

      // Unlink from the Hashtable prior to freeing

      unlink_entry(to_remove);

      FREE_C_HEAP_ARRAY(char, to_remove);

    }

  }

  assert(number_of_entries() == 0, "should have removed all entries");

  assert(new_entry_free_list() == NULL, "entry present on PackageEntryTable's free list");

  free_buckets();

}

PackageEntry* PackageEntryTable::new_entry(unsigned int hash, Symbol* name, ModuleEntry* module) {

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

  PackageEntry* entry = (PackageEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name);

  JFR_ONLY(INIT_ID(entry);)

  // Initialize fields specific to a PackageEntry

  entry->init();

  entry->name()->increment_refcount();

  entry->set_module(module);

  return entry;

}

void PackageEntryTable::add_entry(int index, PackageEntry* new_entry) {

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

  Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);

}

// 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* PackageEntryTable::locked_create_entry_or_null(Symbol* name, ModuleEntry* module) {

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

  // Check if package already exists.  Return NULL if it does.

  if (lookup_only(name) != NULL) {

    return NULL;

  } else {

    PackageEntry* entry = new_entry(compute_hash(name), name, module);

    add_entry(index_for(name), entry);

    return entry;

  }

}

PackageEntry* PackageEntryTable::lookup(Symbol* name, ModuleEntry* module) {

  PackageEntry* p = lookup_only(name);

  if (p != NULL) {

    return p;

  } else {

    // If not found, add to table. Grab the PackageEntryTable lock first.

    MutexLocker ml(Module_lock);

    // Since look-up was done lock-free, we need to check if another thread beat

    // us in the race to insert the package.

    PackageEntry* test = lookup_only(name);

    if (test != NULL) {

      // A race occurred and another thread introduced the package.

      return test;

    } else {

      assert(module != NULL, "module should never be null");

      PackageEntry* entry = new_entry(compute_hash(name), name, module);

      add_entry(index_for(name), entry);

      return entry;

    }

  }

}

PackageEntry* PackageEntryTable::lookup_only(Symbol* name) {

  int index = index_for(name);

  for (PackageEntry* p = bucket(index); p != NULL; p = p->next()) {

    if (p->name()->fast_compare(name) == 0) {

      return p;

    }

  }

  return NULL;

}

// Called when a define module for java.base is being processed.

// Verify the packages loaded thus far are in java.base's package list.

void PackageEntryTable::verify_javabase_packages(GrowableArray<Symbol*> *pkg_list) {

  assert_lock_strong(Module_lock);

  for (int i = 0; i < table_size(); i++) {

    for (PackageEntry* entry = bucket(i);

                       entry != NULL;

                       entry = entry->next()) {

      ModuleEntry* m = entry->module();

      Symbol* module_name = (m == NULL ? NULL : m->name());

      if (module_name != NULL &&

          (module_name->fast_compare(vmSymbols::java_base()) == 0) &&

          !pkg_list->contains(entry->name())) {

        ResourceMark rm;

        vm_exit_during_initialization("A non-" JAVA_BASE_NAME " package was loaded prior to module system initialization", entry->name()->as_C_string());

      }

    }

  }

}

// iteration of qualified exports

void PackageEntry::package_exports_do(ModuleClosure* f) {

  assert_locked_or_safepoint(Module_lock);

  assert(f != NULL, "invariant");

  if (has_qual_exports_list()) {

    int qe_len = _qualified_exports->length();

    for (int i = 0; i < qe_len; ++i) {

      f->do_module(_qualified_exports->at(i));

    }

  }

}

bool PackageEntry::exported_pending_delete() const {

  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");

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

}

// Remove dead entries from all packages' exported list

void PackageEntryTable::purge_all_package_exports() {

  assert_locked_or_safepoint(Module_lock);

  for (int i = 0; i < table_size(); i++) {

    for (PackageEntry* entry = bucket(i);

                       entry != NULL;

                       entry = entry->next()) {

      if (entry->exported_pending_delete()) {

        // exported list is pending deletion due to a transition

        // from qualified to unqualified

        entry->delete_qualified_exports();

      } else if (entry->is_qual_exported()) {

        entry->purge_qualified_exports();

      }

    }

  }

}

void PackageEntryTable::print(outputStream* st) {

  st->print_cr("Package Entry Table (table_size=%d, entries=%d)",

               table_size(), number_of_entries());

  for (int i = 0; i < table_size(); i++) {

    for (PackageEntry* probe = bucket(i);

                       probe != NULL;

                       probe = probe->next()) {

      probe->print(st);

    }

  }

}

// This function may be called from debuggers so access private fields directly

// to prevent triggering locking-related asserts that could result from calling

// getter methods.

void PackageEntry::print(outputStream* st) {

  ResourceMark rm;

  st->print_cr("package entry " PTR_FORMAT " name %s module %s classpath_index "

               INT32_FORMAT " is_exported_unqualified %d is_exported_allUnnamed %d " "next " PTR_FORMAT,

               p2i(this), name()->as_C_string(),

               (module()->is_named() ? module()->name()->as_C_string() : UNNAMED_MODULE),

               _classpath_index, _export_flags == PKG_EXP_UNQUALIFIED,

               _export_flags == PKG_EXP_ALLUNNAMED, p2i(next()));

}

void PackageEntryTable::verify() {

  verify_table<PackageEntry>("Package Entry Table");

}

void PackageEntry::verify() {

  guarantee(name() != NULL, "A package entry must have a corresponding symbol name.");

}