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
45 class 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.
58 class ModuleEntry : public HashtableEntry<Symbol*, mtModule> {
59 private:
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
75 public:
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
180 class 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 //
199 class ModuleEntryTable : public Hashtable<Symbol*, mtModule> {
200 friend class VMStructs;
201 public:
202 enum Constants {
203 _moduletable_entry_size = 109 // number of entries in module entry table
204 };
205
206 private:
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
222 public:
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