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#ifndef SHARE_VM_CLASSFILE_MODULEENTRY_HPP
26#define SHARE_VM_CLASSFILE_MODULEENTRY_HPP
27
28#include "classfile/classLoaderData.hpp"
29#include "classfile/vmSymbols.hpp"
30#include "oops/oopHandle.hpp"
31#include "oops/symbol.hpp"
32#include "prims/jni.h"
33#include "runtime/jniHandles.hpp"
34#include "runtime/mutexLocker.hpp"
35#include "trace/traceMacros.hpp"
36#include "utilities/growableArray.hpp"
37#include "utilities/hashtable.hpp"
38#include "utilities/ostream.hpp"
39
40#define UNNAMED_MODULE "Unnamed Module"
41#define JAVAPKG "java"
42#define JAVAPKG_LEN 4
43#define JAVA_BASE_NAME "java.base"
44
45class ModuleClosure;
46
47// A ModuleEntry describes a module that has been defined by a call to JVM_DefineModule.
48// It contains:
49//   - Symbol* containing the module's name.
50//   - pointer to the java.lang.Module for this module.
51//   - pointer to the java.security.ProtectionDomain shared by classes defined to this module.
52//   - ClassLoaderData*, class loader of this module.
53//   - a growable array containg other module entries that this module can read.
54//   - a flag indicating if this module can read all unnamed modules.
55//
56// The Mutex Module_lock is shared between ModuleEntry and PackageEntry, to lock either
57// data structure.
58class ModuleEntry : public HashtableEntry<Symbol*, mtModule> {
59private:
60  OopHandle _module;                   // java.lang.Module
61  OopHandle _pd;                       // java.security.ProtectionDomain, cached
62                                       // for shared classes from this module
63  ClassLoaderData* _loader_data;
64  GrowableArray<ModuleEntry*>* _reads; // list of modules that are readable by this module
65  Symbol* _version;                    // module version number
66  Symbol* _location;                   // module location
67  bool _can_read_all_unnamed;
68  bool _has_default_read_edges;        // JVMTI redefine/retransform support
69  bool _must_walk_reads;               // walk module's reads list at GC safepoints to purge out dead modules
70  bool _is_open;                       // whether the packages in the module are all unqualifiedly exported
71  bool _is_patched;                    // whether the module is patched via --patch-module
72  TRACE_DEFINE_TRACE_ID_FIELD;
73  enum {MODULE_READS_SIZE = 101};      // Initial size of list of modules that the module can read.
74
75public:
76  void init() {
77    _module = NULL;
78    _loader_data = NULL;
79    _pd = NULL;
80    _reads = NULL;
81    _version = NULL;
82    _location = NULL;
83    _can_read_all_unnamed = false;
84    _has_default_read_edges = false;
85    _must_walk_reads = false;
86    _is_patched = false;
87    _is_open = false;
88  }
89
90  Symbol*          name() const                        { return literal(); }
91  void             set_name(Symbol* n)                 { set_literal(n); }
92
93  oop              module() const                      { return _module.resolve(); }
94  OopHandle        module_handle() const               { return _module; }
95  void             set_module(OopHandle j)             { _module = j; }
96
97  // The shared ProtectionDomain reference is set once the VM loads a shared class
98  // originated from the current Module. The referenced ProtectionDomain object is
99  // created by the ClassLoader when loading a class (shared or non-shared) from the
100  // Module for the first time. This ProtectionDomain object is used for all
101  // classes from the Module loaded by the same ClassLoader.
102  oop              shared_protection_domain();
103  void             set_shared_protection_domain(ClassLoaderData *loader_data, Handle pd);
104
105  ClassLoaderData* loader_data() const                 { return _loader_data; }
106  void             set_loader_data(ClassLoaderData* l) { _loader_data = l; }
107
108  Symbol*          version() const                     { return _version; }
109  void             set_version(Symbol* version);
110
111  Symbol*          location() const                    { return _location; }
112  void             set_location(Symbol* location);
113  bool             is_non_jdk_module();
114
115  bool             can_read(ModuleEntry* m) const;
116  bool             has_reads_list() const;
117  void             add_read(ModuleEntry* m);
118  void             set_read_walk_required(ClassLoaderData* m_loader_data);
119
120  bool             is_open() const                     { return _is_open; }
121  void             set_is_open(bool is_open);
122
123  bool             is_named() const                    { return (name() != NULL); }
124
125  bool can_read_all_unnamed() const {
126    assert(is_named() || _can_read_all_unnamed == true,
127           "unnamed modules can always read all unnamed modules");
128    return _can_read_all_unnamed;
129  }
130
131  // Modules can only go from strict to loose.
132  void set_can_read_all_unnamed() { _can_read_all_unnamed = true; }
133
134  bool has_default_read_edges() const {
135    return _has_default_read_edges;
136  }
137
138  // Sets true and returns the previous value.
139  bool set_has_default_read_edges() {
140    MutexLocker ml(Module_lock);
141    bool prev = _has_default_read_edges;
142    _has_default_read_edges = true;
143    return prev;
144  }
145
146  void set_is_patched() {
147      _is_patched = true;
148  }
149  bool is_patched() {
150      return _is_patched;
151  }
152
153  ModuleEntry* next() const {
154    return (ModuleEntry*)HashtableEntry<Symbol*, mtModule>::next();
155  }
156  ModuleEntry** next_addr() {
157    return (ModuleEntry**)HashtableEntry<Symbol*, mtModule>::next_addr();
158  }
159
160  // iteration support for readability
161  void module_reads_do(ModuleClosure* const f);
162
163  TRACE_DEFINE_TRACE_ID_METHODS;
164
165  // Purge dead weak references out of reads list when any given class loader is unloaded.
166  void purge_reads();
167  void delete_reads();
168
169  // Special handling for unnamed module, one per class loader
170  static ModuleEntry* create_unnamed_module(ClassLoaderData* cld);
171  static ModuleEntry* create_boot_unnamed_module(ClassLoaderData* cld);
172  static ModuleEntry* new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld);
173  void delete_unnamed_module();
174
175  void print(outputStream* st = tty);
176  void verify();
177};
178
179// Iterator interface
180class ModuleClosure: public StackObj {
181 public:
182  virtual void do_module(ModuleEntry* const module) = 0;
183};
184
185
186// The ModuleEntryTable is a Hashtable containing a list of all modules defined
187// by a particular class loader.  Each module is represented as a ModuleEntry node.
188//
189// Each ModuleEntryTable contains a _javabase_module field which allows for the
190// creation of java.base's ModuleEntry very early in bootstrapping before the
191// corresponding JVM_DefineModule call for java.base occurs during module system
192// initialization.  Setting up java.base's ModuleEntry early enables classes,
193// loaded prior to the module system being initialized to be created with their
194// PackageEntry node's correctly pointing at java.base's ModuleEntry.  No class
195// outside of java.base is allowed to be loaded pre-module system initialization.
196//
197// The ModuleEntryTable's lookup is lock free.
198//
199class ModuleEntryTable : public Hashtable<Symbol*, mtModule> {
200  friend class VMStructs;
201public:
202  enum Constants {
203    _moduletable_entry_size  = 109 // number of entries in module entry table
204  };
205
206private:
207  static ModuleEntry* _javabase_module;
208
209  ModuleEntry* new_entry(unsigned int hash, Handle module_handle, bool is_open,
210                         Symbol* name, Symbol* version, Symbol* location, ClassLoaderData* loader_data);
211  void add_entry(int index, ModuleEntry* new_entry);
212
213  int entry_size() const { return BasicHashtable<mtModule>::entry_size(); }
214
215  ModuleEntry** bucket_addr(int i) {
216    return (ModuleEntry**)Hashtable<Symbol*, mtModule>::bucket_addr(i);
217  }
218
219  static unsigned int compute_hash(Symbol* name) { return ((name == NULL) ? 0 : (unsigned int)(name->identity_hash())); }
220  int index_for(Symbol* name) const              { return hash_to_index(compute_hash(name)); }
221
222public:
223  ModuleEntryTable(int table_size);
224  ~ModuleEntryTable();
225
226  ModuleEntry* bucket(int i) {
227    return (ModuleEntry*)Hashtable<Symbol*, mtModule>::bucket(i);
228  }
229
230  // Create module in loader's module entry table, if already exists then
231  // return null.  Assume Module_lock has been locked by caller.
232  ModuleEntry* locked_create_entry_or_null(Handle module_handle,
233                                           bool is_open,
234                                           Symbol* module_name,
235                                           Symbol* module_version,
236                                           Symbol* module_location,
237                                           ClassLoaderData* loader_data);
238
239  // Only lookup module within loader's module entry table.  The table read is lock-free.
240  ModuleEntry* lookup_only(Symbol* name);
241
242  // purge dead weak references out of reads list
243  void purge_all_module_reads();
244
245  // Special handling for java.base
246  static ModuleEntry* javabase_moduleEntry()                   { return _javabase_module; }
247  static void set_javabase_moduleEntry(ModuleEntry* java_base) { _javabase_module = java_base; }
248
249  static bool javabase_defined() { return ((_javabase_module != NULL) &&
250                                           (_javabase_module->module() != NULL)); }
251  static void finalize_javabase(Handle module_handle, Symbol* version, Symbol* location);
252  static void patch_javabase_entries(Handle module_handle);
253
254  void print(outputStream* st = tty);
255  void verify();
256};
257
258#endif // SHARE_VM_CLASSFILE_MODULEENTRY_HPP
259