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/symbol.hpp"
31 #include "prims/jni.h"
32 #include "runtime/mutexLocker.hpp"
33 #include "trace/traceMacros.hpp"
34 #include "utilities/growableArray.hpp"
35 #include "utilities/hashtable.hpp"
36 #include "utilities/ostream.hpp"
37
38 #define UNNAMED_MODULE "Unnamed Module"
39 #define JAVAPKG "java/"
40 #define JAVAPKG_LEN 5
41 #define JAVA_BASE_NAME "java.base"
42
43 class ModuleClosure;
44
45 // A ModuleEntry describes a module that has been defined by a call to JVM_DefineModule.
46 // It contains:
47 // - Symbol* containing the module's name.
48 // - pointer to the java.lang.reflect.Module for this module.
49 // - pointer to the java.security.ProtectionDomain shared by classes defined to this module.
50 // - ClassLoaderData*, class loader of this module.
51 // - a growable array containg other module entries that this module can read.
52 // - a flag indicating if this module can read all unnamed modules.
53 //
54 // The Mutex Module_lock is shared between ModuleEntry and PackageEntry, to lock either
55 // data structure.
56 class ModuleEntry : public HashtableEntry<Symbol*, mtModule> {
57 private:
58 jobject _module; // java.lang.reflect.Module
59 jobject _pd; // java.security.ProtectionDomain, cached
60 // for shared classes from this module
61 ClassLoaderData* _loader_data;
62 GrowableArray<ModuleEntry*>* _reads; // list of modules that are readable by this module
63 Symbol* _version; // module version number
64 Symbol* _location; // module location
65 bool _can_read_all_unnamed;
66 bool _has_default_read_edges; // JVMTI redefine/retransform support
67 bool _must_walk_reads; // walk module's reads list at GC safepoints to purge out dead modules
68 bool _is_open; // whether the packages in the module are all unqualifiedly exported
69 bool _is_patched; // whether the module is patched via --patch-module
70 TRACE_DEFINE_TRACE_ID_FIELD;
71 enum {MODULE_READS_SIZE = 101}; // Initial size of list of modules that the module can read.
72
73 public:
74 void init() {
75 _module = NULL;
76 _loader_data = NULL;
77 _pd = NULL;
78 _reads = NULL;
79 _version = NULL;
80 _location = NULL;
81 _can_read_all_unnamed = false;
82 _has_default_read_edges = false;
83 _must_walk_reads = false;
84 _is_patched = false;
85 _is_open = false;
86 }
87
88 Symbol* name() const { return literal(); }
89 void set_name(Symbol* n) { set_literal(n); }
90
91 jobject module() const { return _module; }
92 void set_module(jobject j) { _module = j; }
93
94 // The shared ProtectionDomain reference is set once the VM loads a shared class
95 // originated from the current Module. The referenced ProtectionDomain object is
96 // created by the ClassLoader when loading a class (shared or non-shared) from the
97 // Module for the first time. This ProtectionDomain object is used for all
98 // classes from the Module loaded by the same ClassLoader.
99 Handle shared_protection_domain();
100 void set_shared_protection_domain(ClassLoaderData *loader_data, Handle pd);
101
102 ClassLoaderData* loader_data() const { return _loader_data; }
103 void set_loader_data(ClassLoaderData* l) { _loader_data = l; }
104
105 Symbol* version() const { return _version; }
106 void set_version(Symbol* version);
107
108 Symbol* location() const { return _location; }
109 void set_location(Symbol* location);
110 bool is_non_jdk_module();
111
112 bool can_read(ModuleEntry* m) const;
113 bool has_reads() const;
114 void add_read(ModuleEntry* m);
115 void set_read_walk_required(ClassLoaderData* m_loader_data);
116
117 bool is_open() const { return _is_open; }
118 void set_is_open(bool is_open);
119
120 bool is_named() const { return (name() != NULL); }
121
122 bool can_read_all_unnamed() const {
123 assert(is_named() || _can_read_all_unnamed == true,
124 "unnamed modules can always read all unnamed modules");
125 return _can_read_all_unnamed;
126 }
127
128 // Modules can only go from strict to loose.
129 void set_can_read_all_unnamed() { _can_read_all_unnamed = true; }
130
131 bool has_default_read_edges() const {
132 return _has_default_read_edges;
133 }
134
135 // Sets true and returns the previous value.
136 bool set_has_default_read_edges() {
137 MutexLocker ml(Module_lock);
138 bool prev = _has_default_read_edges;
139 _has_default_read_edges = true;
140 return prev;
141 }
142
143 void set_is_patched() {
144 _is_patched = true;
145 }
146 bool is_patched() {
147 return _is_patched;
148 }
149
150 ModuleEntry* next() const {
151 return (ModuleEntry*)HashtableEntry<Symbol*, mtModule>::next();
152 }
153 ModuleEntry** next_addr() {
154 return (ModuleEntry**)HashtableEntry<Symbol*, mtModule>::next_addr();
155 }
156
157 // iteration support for readability
158 void module_reads_do(ModuleClosure* const f);
159
160 TRACE_DEFINE_TRACE_ID_METHODS;
161
162 // Purge dead weak references out of reads list when any given class loader is unloaded.
163 void purge_reads();
164 void delete_reads();
165
166 void print(outputStream* st = tty);
167 void verify();
168 };
169
170 // Iterator interface
171 class ModuleClosure: public StackObj {
172 public:
173 virtual void do_module(ModuleEntry* const module) = 0;
174 };
175
176
177 // The ModuleEntryTable is a Hashtable containing a list of all modules defined
178 // by a particular class loader. Each module is represented as a ModuleEntry node.
179 //
180 // Each ModuleEntryTable contains a _javabase_module field which allows for the
181 // creation of java.base's ModuleEntry very early in bootstrapping before the
182 // corresponding JVM_DefineModule call for java.base occurs during module system
183 // initialization. Setting up java.base's ModuleEntry early enables classes,
184 // loaded prior to the module system being initialized to be created with their
185 // PackageEntry node's correctly pointing at java.base's ModuleEntry. No class
186 // outside of java.base is allowed to be loaded pre-module system initialization.
187 //
188 // The ModuleEntryTable's lookup is lock free.
189 //
190 class ModuleEntryTable : public Hashtable<Symbol*, mtModule> {
191 friend class VMStructs;
192 public:
193 enum Constants {
194 _moduletable_entry_size = 109 // number of entries in module entry table
195 };
196
197 private:
198 static ModuleEntry* _javabase_module;
199 ModuleEntry* _unnamed_module;
200
201 ModuleEntry* new_entry(unsigned int hash, Handle module_handle, bool is_open,
202 Symbol* name, Symbol* version, Symbol* location, ClassLoaderData* loader_data);
203 void add_entry(int index, ModuleEntry* new_entry);
204
205 int entry_size() const { return BasicHashtable<mtModule>::entry_size(); }
206
207 ModuleEntry** bucket_addr(int i) {
208 return (ModuleEntry**)Hashtable<Symbol*, mtModule>::bucket_addr(i);
209 }
210
211 static unsigned int compute_hash(Symbol* name) { return ((name == NULL) ? 0 : (unsigned int)(name->identity_hash())); }
212 int index_for(Symbol* name) const { return hash_to_index(compute_hash(name)); }
213
214 public:
215 ModuleEntryTable(int table_size);
216 ~ModuleEntryTable();
217
218 ModuleEntry* bucket(int i) {
219 return (ModuleEntry*)Hashtable<Symbol*, mtModule>::bucket(i);
220 }
221
222 // Create module in loader's module entry table, if already exists then
223 // return null. Assume Module_lock has been locked by caller.
224 ModuleEntry* locked_create_entry_or_null(Handle module_handle,
225 bool is_open,
226 Symbol* module_name,
227 Symbol* module_version,
228 Symbol* module_location,
229 ClassLoaderData* loader_data);
230
231 // Only lookup module within loader's module entry table. The table read is lock-free.
232 ModuleEntry* lookup_only(Symbol* name);
233
234 // purge dead weak references out of reads list
235 void purge_all_module_reads();
236
237 // Special handling for unnamed module, one per class loader's ModuleEntryTable
238 void create_unnamed_module(ClassLoaderData* loader_data);
239 ModuleEntry* unnamed_module() { return _unnamed_module; }
240
241 // Special handling for java.base
242 static ModuleEntry* javabase_moduleEntry() { return _javabase_module; }
243 static void set_javabase_moduleEntry(ModuleEntry* java_base) { _javabase_module = java_base; }
244 static bool javabase_defined() { return ((_javabase_module != NULL) &&
245 (_javabase_module->module() != NULL)); }
246 static void finalize_javabase(Handle module_handle, Symbol* version, Symbol* location);
247 static void patch_javabase_entries(Handle module_handle);
248
249 void print(outputStream* st = tty);
250 void verify();
251 };
252
253 #endif // SHARE_VM_CLASSFILE_MODULEENTRY_HPP