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