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