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, module)) {

    81       ResourceMark rm;

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

    83       log_trace(module)("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, module)) {

   140       ResourceMark rm;

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

   142       ModuleEntry* pkg_mod = module();

   143       log_trace(module)("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   // Walk through all buckets and all entries in each bucket,

   178   // freeing each entry.

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

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

   181       PackageEntry* to_remove = p;

   182       // read next before freeing.

   183       p = p->next();

   184 

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

   186       to_remove->delete_qualified_exports();

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

   188 

   189       // Unlink from the Hashtable prior to freeing

   190       unlink_entry(to_remove);

   191       FREE_C_HEAP_ARRAY(char, to_remove);

   192     }

   193   }

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

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

   196   free_buckets();

   197 }

   198 

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

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

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

   202 

   203   TRACE_INIT_ID(entry);

   204 

   205   // Initialize fields specific to a PackageEntry

   206   entry->init();

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

   208   entry->set_module(module);

   209   return entry;

   210 }

   211 

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

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

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

   215 }

   216 

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

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

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

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

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

   222   if (lookup_only(name) != NULL) {

   223     return NULL;

   224   } else {

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

   226     add_entry(index_for(name), entry);

   227     return entry;

   228   }

   229 }

   230 

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

   232   PackageEntry* p = lookup_only(name);

   233   if (p != NULL) {

   234     return p;

   235   } else {

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

   237     MutexLocker ml(Module_lock);

   238 

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

   240     // us in the race to insert the package.

   241     PackageEntry* test = lookup_only(name);

   242     if (test != NULL) {

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

   244       return test;

   245     } else {

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

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

   248       add_entry(index_for(name), entry);

   249       return entry;

   250     }

   251   }

   252 }

   253 

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

   255   int index = index_for(name);

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

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

   258       return p;

   259     }

   260   }

   261   return NULL;

   262 }

   263 

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

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

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

   267   assert_lock_strong(Module_lock);

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

   269     for (PackageEntry* entry = bucket(i);

   270                        entry != NULL;

   271                        entry = entry->next()) {

   272       ModuleEntry* m = entry->module();

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

   274       if (module_name != NULL &&

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

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

   277         ResourceMark rm;

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

   279       }

   280     }

   281   }

   282 

   283 }

   284 

   285 // iteration of qualified exports

   286 void PackageEntry::package_exports_do(ModuleClosure* const f) {

   287   assert_locked_or_safepoint(Module_lock);

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

   289 

   290   if (has_qual_exports_list()) {

   291     int qe_len = _qualified_exports->length();

   292 

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

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

   295     }

   296   }

   297 }

   298 

   299 bool PackageEntry::exported_pending_delete() const {

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

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

   302 }

   303 

   304 // Remove dead entries from all packages' exported list

   305 void PackageEntryTable::purge_all_package_exports() {

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

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

   308     for (PackageEntry* entry = bucket(i);

   309                        entry != NULL;

   310                        entry = entry->next()) {

   311       if (entry->exported_pending_delete()) {

   312         // exported list is pending deletion due to a transition

   313         // from qualified to unqualified

   314         entry->delete_qualified_exports();

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

   316         entry->purge_qualified_exports();

   317       }

   318     }

   319   }

   320 }

   321 

   322 void PackageEntryTable::print(outputStream* st) {

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

   324                table_size(), number_of_entries());

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

   326     for (PackageEntry* probe = bucket(i);

   327                        probe != NULL;

   328                        probe = probe->next()) {

   329       probe->print(st);

   330     }

   331   }

   332 }

   333 

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

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

   336 // getter methods.

   337 void PackageEntry::print(outputStream* st) {

   338   ResourceMark rm;

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

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

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

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

   343                _classpath_index, _export_flags == PKG_EXP_UNQUALIFIED,

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

   345 }

   346 

   347 void PackageEntryTable::verify() {

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

   349 }

   350 

   351 void PackageEntry::verify() {

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

   353 }