8142968: Module System implementation

Initial integration of JEP 200, JEP 260, JEP 261, and JEP 282

Co-authored-by: Alex Buckley <alex.buckley@oracle.com>
Co-authored-by: Jonathan Gibbons <jonathan.gibbons@oracle.com>
Co-authored-by: Karen Kinnear <karen.kinnear@oracle.com>
Co-authored-by: Mandy Chung <mandy.chung@oracle.com>
Co-authored-by: Mark Reinhold <mark.reinhold@oracle.com>
Co-authored-by: Harold Seigel <harold.seigel@oracle.com>
Co-authored-by: Lois Foltan <lois.foltan@oracle.com>
Co-authored-by: Calvin Cheung <calvin.cheung@oracle.com>
Co-authored-by: Christian Tornqvist <christian.tornqvist@oracle.com>
Co-authored-by: Erik Joelsson <erik.joelsson@oracle.com>
Co-authored-by: George Triantafillou <george.triantafillou@oracle.com>
Co-authored-by: Igor Ignatyev <igor.ignatyev@oracle.com>
Co-authored-by: Ioi Lam <ioi.lam@oracle.com>
Co-authored-by: James Laskey <james.laskey@oracle.com>
Co-authored-by: Jean-Francois Denise <jean-francois.denise@oracle.com>
Co-authored-by: Jiangli Zhou <jiangli.zhou@oracle.com>
Co-authored-by: Markus Gronlund <markus.gronlund@oracle.com>
Co-authored-by: Serguei Spitsyn <serguei.spitsyn@oracle.com>
Co-authored-by: Staffan Larsen <staffan.larsen@oracle.com>
Co-authored-by: Sundararajan Athijegannathan <sundararajan.athijegannathan@oracle.com>
Reviewed-by: acorn, ccheung, coleenp, ctornqvi, dholmes, dsimms, gtriantafill, iklam, jiangli, mgronlun, mseledtsov, cjplummer, sspitsyn, stefank, twisti, hseigel, lfoltan, alanb, mchung, dfazunen

hotspot/src/share/vm/classfile/moduleEntry.cpp

@@ -0,0 +1,405 @@
+/*
+ * Copyright (c) 2016, 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/classLoaderData.hpp"
+#include "classfile/javaClasses.hpp"
+#include "classfile/moduleEntry.hpp"
+#include "logging/log.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/symbol.hpp"
+#include "prims/jni.h"
+#include "runtime/handles.inline.hpp"
+#include "runtime/safepoint.hpp"
+#include "trace/traceMacros.hpp"
+#include "utilities/events.hpp"
+#include "utilities/growableArray.hpp"
+#include "utilities/hashtable.inline.hpp"
+
+ModuleEntry* ModuleEntryTable::_javabase_module = NULL;
+
+
+void ModuleEntry::set_location(Symbol* location) {
+  if (_location != NULL) {
+    // _location symbol's refcounts are managed by ModuleEntry,
+    // must decrement the old one before updating.
+    _location->decrement_refcount();
+  }
+
+  _location = location;
+
+  if (location != NULL) {
+    location->increment_refcount();
+  }
+}
+
+void ModuleEntry::set_version(Symbol* version) {
+  if (_version != NULL) {
+    // _version symbol's refcounts are managed by ModuleEntry,
+    // must decrement the old one before updating.
+    _version->decrement_refcount();
+  }
+
+  _version = version;
+
+  if (version != NULL) {
+    version->increment_refcount();
+  }
+}
+
+// Returns the shared ProtectionDomain
+Handle ModuleEntry::shared_protection_domain() {
+  return Handle(JNIHandles::resolve(_pd));
+}
+
+// Set the shared ProtectionDomain atomically
+void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
+                                               Handle pd_h) {
+  // Create a JNI handle for the shared ProtectionDomain and save it atomically.
+  // If someone beats us setting the _pd cache, the created JNI handle is destroyed.
+  jobject obj = loader_data->add_handle(pd_h);
+  if (Atomic::cmpxchg_ptr(obj, &_pd, NULL) != NULL) {
+    loader_data->remove_handle(obj);
+  }
+}
+
+// Returns true if this module can read module m
+bool ModuleEntry::can_read(ModuleEntry* m) const {
+  assert(m != NULL, "No module to lookup in this module's reads list");
+
+  // Unnamed modules read everyone and all modules
+  // read java.base.  If either of these conditions
+  // hold, readability has been established.
+  if (!this->is_named() ||
+      (m == ModuleEntryTable::javabase_module())) {
+    return true;
+  }
+
+  MutexLocker m1(Module_lock);
+  if (!has_reads()) {
+    return false;
+  } else {
+    return _reads->contains(m);
+  }
+}
+
+// Add a new module to this module's reads list
+void ModuleEntry::add_read(ModuleEntry* m) {
+  MutexLocker m1(Module_lock);
+  if (m == NULL) {
+    set_can_read_all_unnamed();
+  } else {
+    if (_reads == NULL) {
+      // Lazily create a module's reads list
+      _reads = new (ResourceObj::C_HEAP, mtClass)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
+    }
+    _reads->append_if_missing(m);
+  }
+}
+
+bool ModuleEntry::has_reads() const {
+  assert_locked_or_safepoint(Module_lock);
+  return ((_reads != NULL) && !_reads->is_empty());
+}
+
+// Purge dead module entries out of reads list.
+void ModuleEntry::purge_reads() {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+  if (has_reads()) {
+    // Go backwards because this removes entries that are dead.
+    int len = _reads->length();
+    for (int idx = len - 1; idx >= 0; idx--) {
+      ModuleEntry* module_idx = _reads->at(idx);
+      ClassLoaderData* cld = module_idx->loader();
+      if (cld->is_unloading()) {
+        _reads->delete_at(idx);
+      }
+    }
+  }
+}
+
+void ModuleEntry::module_reads_do(ModuleClosure* const f) {
+  assert_locked_or_safepoint(Module_lock);
+  assert(f != NULL, "invariant");
+
+  if (has_reads()) {
+    int reads_len = _reads->length();
+    for (int i = 0; i < reads_len; ++i) {
+      f->do_module(_reads->at(i));
+    }
+  }
+}
+
+void ModuleEntry::delete_reads() {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+  delete _reads;
+  _reads = NULL;
+}
+
+ModuleEntryTable::ModuleEntryTable(int table_size)
+  : Hashtable<Symbol*, mtClass>(table_size, sizeof(ModuleEntry)), _unnamed_module(NULL)
+{
+}
+
+ModuleEntryTable::~ModuleEntryTable() {
+  assert_locked_or_safepoint(Module_lock);
+
+  // Walk through all buckets and all entries in each bucket,
+  // freeing each entry.
+  for (int i = 0; i < table_size(); ++i) {
+    for (ModuleEntry* m = bucket(i); m != NULL;) {
+      ModuleEntry* to_remove = m;
+      // read next before freeing.
+      m = m->next();
+
+      ResourceMark rm;
+      log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
+                         to_remove->name()->as_C_string() : UNNAMED_MODULE);
+
+      // Clean out the C heap allocated reads list first before freeing the entry
+      to_remove->delete_reads();
+      if (to_remove->name() != NULL) {
+        to_remove->name()->decrement_refcount();
+      }
+      if (to_remove->version() != NULL) {
+        to_remove->version()->decrement_refcount();
+      }
+      if (to_remove->location() != NULL) {
+        to_remove->location()->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 ModuleEntryTable's free list");
+  free_buckets();
+}
+
+void ModuleEntryTable::create_unnamed_module(ClassLoaderData* loader_data) {
+  assert_locked_or_safepoint(Module_lock);
+
+  // Each ModuleEntryTable has exactly one unnamed module
+  if (loader_data->is_the_null_class_loader_data()) {
+    // For the boot loader, the java.lang.reflect.Module for the unnamed module
+    // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
+    // this point initially create the ModuleEntry for the unnamed module.
+    _unnamed_module = new_entry(0, Handle(NULL), NULL, NULL, NULL, loader_data);
+  } else {
+    // For all other class loaders the java.lang.reflect.Module for their
+    // corresponding unnamed module can be found in the java.lang.ClassLoader object.
+    oop module = java_lang_ClassLoader::unnamedModule(loader_data->class_loader());
+    _unnamed_module = new_entry(0, Handle(module), NULL, NULL, NULL, loader_data);
+
+    // Store pointer to the ModuleEntry in the unnamed module's java.lang.reflect.Module
+    // object.
+    java_lang_reflect_Module::set_module_entry(module, _unnamed_module);
+  }
+
+  // Add to bucket 0, no name to hash on
+  add_entry(0, _unnamed_module);
+}
+
+ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle, Symbol* name,
+                                         Symbol* version, Symbol* location,
+                                         ClassLoaderData* loader_data) {
+  assert_locked_or_safepoint(Module_lock);
+  ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtClass);
+
+  // Initialize everything BasicHashtable would
+  entry->set_next(NULL);
+  entry->set_hash(hash);
+  entry->set_literal(name);
+
+  // Initialize fields specific to a ModuleEntry
+  entry->init();
+  if (name != NULL) {
+    name->increment_refcount();
+  } else {
+    // Unnamed modules can read all other unnamed modules.
+    entry->set_can_read_all_unnamed();
+  }
+
+  if (!module_handle.is_null()) {
+    entry->set_module(loader_data->add_handle(module_handle));
+  }
+
+  entry->set_loader(loader_data);
+  entry->set_version(version);
+  entry->set_location(location);
+
+  TRACE_INIT_MODULE_ID(entry);
+
+  return entry;
+}
+
+void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
+  assert_locked_or_safepoint(Module_lock);
+  Hashtable<Symbol*, mtClass>::add_entry(index, (HashtableEntry<Symbol*, mtClass>*)new_entry);
+}
+
+ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
+                                                           Symbol* module_name,
+                                                           Symbol* module_version,
+                                                           Symbol* module_location,
+                                                           ClassLoaderData* loader_data) {
+  assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
+  assert_locked_or_safepoint(Module_lock);
+  // Check if module already exists.
+  if (lookup_only(module_name) != NULL) {
+    return NULL;
+  } else {
+    ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, module_name,
+                                   module_version, module_location, loader_data);
+    add_entry(index_for(module_name), entry);
+    return entry;
+  }
+}
+
+// lookup_only by Symbol* to find a ModuleEntry.
+ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
+  if (name == NULL) {
+    // Return this table's unnamed module
+    return unnamed_module();
+  }
+  int index = index_for(name);
+  for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
+    if (m->name()->fast_compare(name) == 0) {
+      return m;
+    }
+  }
+  return NULL;
+}
+
+// Remove dead modules from all other alive modules' reads list.
+// This should only occur at class unloading.
+void ModuleEntryTable::purge_all_module_reads() {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+  for (int i = 0; i < table_size(); i++) {
+    for (ModuleEntry* entry = bucket(i);
+                      entry != NULL;
+                      entry = entry->next()) {
+      entry->purge_reads();
+    }
+  }
+}
+
+void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
+  assert_locked_or_safepoint(Module_lock);
+  ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
+  ModuleEntryTable* module_table = boot_loader_data->modules();
+
+  assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
+
+  if (module_handle.is_null()) {
+    fatal("Unable to finalize module definition for java.base");
+  }
+
+  // Set java.lang.reflect.Module, version and location for java.base
+  ModuleEntry* jb_module = javabase_module();
+  assert(jb_module != NULL, "java.base ModuleEntry not defined");
+  jb_module->set_module(boot_loader_data->add_handle(module_handle));
+  jb_module->set_version(version);
+  jb_module->set_location(location);
+  // Store pointer to the ModuleEntry for java.base in the java.lang.reflect.Module object.
+  java_lang_reflect_Module::set_module_entry(module_handle(), jb_module);
+}
+
+void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
+  if (module_handle.is_null()) {
+    fatal("Unable to patch the module field of classes loaded prior to java.base's definition, invalid java.lang.reflect.Module");
+  }
+
+  // Do the fixups for the basic primitive types
+  java_lang_Class::set_module(Universe::int_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::float_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::double_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::char_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::long_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::short_mirror(), module_handle());
+  java_lang_Class::set_module(Universe::void_mirror(), module_handle());
+
+  // Do the fixups for classes that have already been created.
+  GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
+  int list_length = list->length();
+  for (int i = 0; i < list_length; i++) {
+    Klass* k = list->at(i);
+    assert(k->is_klass(), "List should only hold classes");
+    Thread* THREAD = Thread::current();
+    KlassHandle kh(THREAD, k);
+    java_lang_Class::fixup_module_field(kh, module_handle);
+  }
+
+  delete java_lang_Class::fixup_module_field_list();
+  java_lang_Class::set_fixup_module_field_list(NULL);
+}
+
+#ifndef PRODUCT
+void ModuleEntryTable::print() {
+  tty->print_cr("Module Entry Table (table_size=%d, entries=%d)",
+                table_size(), number_of_entries());
+  for (int i = 0; i < table_size(); i++) {
+    for (ModuleEntry* probe = bucket(i);
+                              probe != NULL;
+                              probe = probe->next()) {
+      probe->print();
+    }
+  }
+}
+
+void ModuleEntry::print() {
+  ResourceMark rm;
+  tty->print_cr("entry "PTR_FORMAT" name %s module "PTR_FORMAT" loader %s version %s location %s strict %s next "PTR_FORMAT,
+                p2i(this),
+                name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
+                p2i(module()),
+                loader()->loader_name(),
+                version() != NULL ? version()->as_C_string() : "NULL",
+                location() != NULL ? location()->as_C_string() : "NULL",
+                BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
+}
+#endif
+
+void ModuleEntryTable::verify() {
+  int element_count = 0;
+  for (int i = 0; i < table_size(); i++) {
+    for (ModuleEntry* probe = bucket(i);
+                              probe != NULL;
+                              probe = probe->next()) {
+      probe->verify();
+      element_count++;
+    }
+  }
+  guarantee(number_of_entries() == element_count,
+            "Verify of Module Entry Table failed");
+  debug_only(verify_lookup_length((double)number_of_entries() / table_size()));
+}
+
+void ModuleEntry::verify() {
+  guarantee(loader() != NULL, "A module entry must be associated with a loader.");
+}