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