1 /*
2 * Copyright (c) 2016, 2018, 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 "jni.h"
29 #include "classfile/classLoaderData.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "oops/oopHandle.hpp"
32 #include "oops/symbol.hpp"
33 #include "runtime/jniHandles.hpp"
34 #include "runtime/mutexLocker.hpp"
35 #include "utilities/growableArray.hpp"
36 #include "utilities/hashtable.hpp"
37 #include "utilities/macros.hpp"
38 #include "utilities/ostream.hpp"
39 #if INCLUDE_JFR
40 #include "jfr/support/jfrTraceIdExtension.hpp"
41 #endif
42
43 #define UNNAMED_MODULE "unnamed Module"
44 #define UNNAMED_MODULE_LEN 14
45 #define JAVAPKG "java"
46 #define JAVAPKG_LEN 4
47 #define JAVA_BASE_NAME "java.base"
48 #define JAVA_BASE_NAME_LEN 9
49
50 class ModuleClosure;
51
52 // A ModuleEntry describes a module that has been defined by a call to JVM_DefineModule.
53 // It contains:
54 // - Symbol* containing the module's name.
55 // - pointer to the java.lang.Module for this module.
56 // - pointer to the java.security.ProtectionDomain shared by classes defined to this module.
57 // - ClassLoaderData*, class loader of this module.
58 // - a growable array containg other module entries that this module can read.
59 // - a flag indicating if this module can read all unnamed modules.
60 //
61 // The Mutex Module_lock is shared between ModuleEntry and PackageEntry, to lock either
62 // data structure.
63 class ModuleEntry : public HashtableEntry<Symbol*, mtModule> {
64 private:
65 OopHandle _module; // java.lang.Module
66 OopHandle _pd; // java.security.ProtectionDomain, cached
67 // for shared classes from this module
68 ClassLoaderData* _loader_data;
69 GrowableArray<ModuleEntry*>* _reads; // list of modules that are readable by this module
70 Symbol* _version; // module version number
71 Symbol* _location; // module location
72 bool _can_read_all_unnamed;
73 bool _has_default_read_edges; // JVMTI redefine/retransform support
74 bool _must_walk_reads; // walk module's reads list at GC safepoints to purge out dead modules
75 bool _is_open; // whether the packages in the module are all unqualifiedly exported
76 bool _is_patched; // whether the module is patched via --patch-module
77 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
78 enum {MODULE_READS_SIZE = 101}; // Initial size of list of modules that the module can read.
79
80 public:
81 void init() {
82 _module = NULL;
83 _loader_data = NULL;
84 _pd = NULL;
85 _reads = NULL;
86 _version = NULL;
87 _location = NULL;
88 _can_read_all_unnamed = false;
89 _has_default_read_edges = false;
90 _must_walk_reads = false;
91 _is_patched = false;
92 _is_open = false;
93 }
94
95 Symbol* name() const { return literal(); }
96 void set_name(Symbol* n) { set_literal(n); }
97
98 oop module() const;
99 OopHandle module_handle() const { return _module; }
100 void set_module(OopHandle j) { _module = j; }
101
102 // The shared ProtectionDomain reference is set once the VM loads a shared class
103 // originated from the current Module. The referenced ProtectionDomain object is
104 // created by the ClassLoader when loading a class (shared or non-shared) from the
105 // Module for the first time. This ProtectionDomain object is used for all
106 // classes from the Module loaded by the same ClassLoader.
107 oop shared_protection_domain();
108 void set_shared_protection_domain(ClassLoaderData *loader_data, Handle pd);
109
110 ClassLoaderData* loader_data() const { return _loader_data; }
111
112 void set_loader_data(ClassLoaderData* cld) {
113 assert(!cld->is_anonymous(), "Unexpected anonymous class loader data");
114 _loader_data = cld;
115 }
116
117 Symbol* version() const { return _version; }
118 void set_version(Symbol* version);
119
120 Symbol* location() const { return _location; }
121 void set_location(Symbol* location);
122 bool should_show_version();
123
124 bool can_read(ModuleEntry* m) const;
125 bool has_reads_list() const;
126 void add_read(ModuleEntry* m);
127 void set_read_walk_required(ClassLoaderData* m_loader_data);
128
129 bool is_open() const { return _is_open; }
130 void set_is_open(bool is_open);
131
132 bool is_named() const { return (name() != NULL); }
133
134 bool can_read_all_unnamed() const {
135 assert(is_named() || _can_read_all_unnamed == true,
136 "unnamed modules can always read all unnamed modules");
137 return _can_read_all_unnamed;
138 }
139
140 // Modules can only go from strict to loose.
141 void set_can_read_all_unnamed() { _can_read_all_unnamed = true; }
142
143 bool has_default_read_edges() const {
144 return _has_default_read_edges;
145 }
146
147 // Sets true and returns the previous value.
148 bool set_has_default_read_edges() {
149 MutexLocker ml(Module_lock);
150 bool prev = _has_default_read_edges;
151 _has_default_read_edges = true;
152 return prev;
153 }
154
155 void set_is_patched() {
156 _is_patched = true;
157 }
158 bool is_patched() {
159 return _is_patched;
160 }
161
162 ModuleEntry* next() const {
163 return (ModuleEntry*)HashtableEntry<Symbol*, mtModule>::next();
164 }
165 ModuleEntry** next_addr() {
166 return (ModuleEntry**)HashtableEntry<Symbol*, mtModule>::next_addr();
167 }
168
169 // iteration support for readability
170 void module_reads_do(ModuleClosure* const f);
171
172 // Purge dead weak references out of reads list when any given class loader is unloaded.
173 void purge_reads();
174 void delete_reads();
175
176 // Special handling for unnamed module, one per class loader
177 static ModuleEntry* create_unnamed_module(ClassLoaderData* cld);
178 static ModuleEntry* create_boot_unnamed_module(ClassLoaderData* cld);
179 static ModuleEntry* new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld);
180 void delete_unnamed_module();
181
182 void print(outputStream* st = tty);
183 void verify();
184
185 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
186 };
187
188 // Iterator interface
189 class ModuleClosure: public StackObj {
190 public:
191 virtual void do_module(ModuleEntry* module) = 0;
192 };
193
194
195 // The ModuleEntryTable is a Hashtable containing a list of all modules defined
196 // by a particular class loader. Each module is represented as a ModuleEntry node.
197 //
198 // Each ModuleEntryTable contains a _javabase_module field which allows for the
199 // creation of java.base's ModuleEntry very early in bootstrapping before the
200 // corresponding JVM_DefineModule call for java.base occurs during module system
201 // initialization. Setting up java.base's ModuleEntry early enables classes,
202 // loaded prior to the module system being initialized to be created with their
203 // PackageEntry node's correctly pointing at java.base's ModuleEntry. No class
204 // outside of java.base is allowed to be loaded pre-module system initialization.
205 //
206 // The ModuleEntryTable's lookup is lock free.
207 //
208 class ModuleEntryTable : public Hashtable<Symbol*, mtModule> {
209 friend class VMStructs;
210 public:
211 enum Constants {
212 _moduletable_entry_size = 109 // number of entries in module entry table
213 };
214
215 private:
216 static ModuleEntry* _javabase_module;
217
218 ModuleEntry* new_entry(unsigned int hash, Handle module_handle, bool is_open,
219 Symbol* name, Symbol* version, Symbol* location, ClassLoaderData* loader_data);
220 void add_entry(int index, ModuleEntry* new_entry);
221
222 int entry_size() const { return BasicHashtable<mtModule>::entry_size(); }
223
224 ModuleEntry** bucket_addr(int i) {
225 return (ModuleEntry**)Hashtable<Symbol*, mtModule>::bucket_addr(i);
226 }
227
228 static unsigned int compute_hash(Symbol* name) { return ((name == NULL) ? 0 : (unsigned int)(name->identity_hash())); }
229 int index_for(Symbol* name) const { return hash_to_index(compute_hash(name)); }
230
231 public:
232 ModuleEntryTable(int table_size);
233 ~ModuleEntryTable();
234
235 ModuleEntry* bucket(int i) {
236 return (ModuleEntry*)Hashtable<Symbol*, mtModule>::bucket(i);
237 }
238
239 // Create module in loader's module entry table, if already exists then
240 // return null. Assume Module_lock has been locked by caller.
241 ModuleEntry* locked_create_entry_or_null(Handle module_handle,
242 bool is_open,
243 Symbol* module_name,
244 Symbol* module_version,
245 Symbol* module_location,
246 ClassLoaderData* loader_data);
247
248 // Only lookup module within loader's module entry table. The table read is lock-free.
249 ModuleEntry* lookup_only(Symbol* name);
250
251 // purge dead weak references out of reads list
252 void purge_all_module_reads();
253
254 // Special handling for java.base
255 static ModuleEntry* javabase_moduleEntry() { return _javabase_module; }
256 static void set_javabase_moduleEntry(ModuleEntry* java_base) { _javabase_module = java_base; }
257
258 static bool javabase_defined() { return ((_javabase_module != NULL) &&
259 (_javabase_module->module() != NULL)); }
260 static void finalize_javabase(Handle module_handle, Symbol* version, Symbol* location);
261 static void patch_javabase_entries(Handle module_handle);
262
263 void print(outputStream* st = tty);
264 void verify();
265 };
266
267 #endif // SHARE_VM_CLASSFILE_MODULEENTRY_HPP