1 /*
2 * Copyright (c) 2016, 2020, 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_CLASSFILE_MODULEENTRY_HPP
26 #define SHARE_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 CDS_ONLY(int _shared_path_index;) // >=0 if classes in this module are in CDS archive
73 bool _can_read_all_unnamed;
74 bool _has_default_read_edges; // JVMTI redefine/retransform support
75 bool _must_walk_reads; // walk module's reads list at GC safepoints to purge out dead modules
76 bool _is_open; // whether the packages in the module are all unqualifiedly exported
77 bool _is_patched; // whether the module is patched via --patch-module
78 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
79 enum {MODULE_READS_SIZE = 101}; // Initial size of list of modules that the module can read.
80
81 public:
82 void init() {
83 _module = OopHandle();
84 _pd = OopHandle();
85 _loader_data = NULL;
86 _reads = NULL;
87 _version = NULL;
88 _location = NULL;
89 _can_read_all_unnamed = false;
90 _has_default_read_edges = false;
91 _must_walk_reads = false;
92 _is_patched = false;
93 _is_open = false;
94 CDS_ONLY(_shared_path_index = -1);
95 }
96
97 Symbol* name() const { return literal(); }
98 void set_name(Symbol* n) { set_literal(n); }
99
100 oop module() const;
101 OopHandle module_handle() const { return _module; }
102 void set_module(OopHandle j) { _module = j; }
103
104 // The shared ProtectionDomain reference is set once the VM loads a shared class
105 // originated from the current Module. The referenced ProtectionDomain object is
106 // created by the ClassLoader when loading a class (shared or non-shared) from the
107 // Module for the first time. This ProtectionDomain object is used for all
108 // classes from the Module loaded by the same ClassLoader.
109 oop shared_protection_domain();
110 void set_shared_protection_domain(ClassLoaderData *loader_data, Handle pd);
111
112 ClassLoaderData* loader_data() const { return _loader_data; }
113
114 void set_loader_data(ClassLoaderData* cld) {
115 assert(!cld->has_class_mirror_holder(), "Unexpected has_class_mirror_holder cld");
116 _loader_data = cld;
117 }
118
119 Symbol* version() const { return _version; }
120 void set_version(Symbol* version);
121
122 Symbol* location() const { return _location; }
123 void set_location(Symbol* location);
124 bool should_show_version();
125
126 bool can_read(ModuleEntry* m) const;
127 bool has_reads_list() const;
128 void add_read(ModuleEntry* m);
129 void set_read_walk_required(ClassLoaderData* m_loader_data);
130
131 bool is_open() const { return _is_open; }
132 void set_is_open(bool is_open);
133
134 bool is_named() const { return (name() != NULL); }
135
136 bool can_read_all_unnamed() const {
137 assert(is_named() || _can_read_all_unnamed == true,
138 "unnamed modules can always read all unnamed modules");
139 return _can_read_all_unnamed;
140 }
141
142 // Modules can only go from strict to loose.
143 void set_can_read_all_unnamed() { _can_read_all_unnamed = true; }
144
145 bool has_default_read_edges() const {
146 return _has_default_read_edges;
147 }
148
149 // Sets true and returns the previous value.
150 bool set_has_default_read_edges() {
151 MutexLocker ml(Module_lock);
152 bool prev = _has_default_read_edges;
153 _has_default_read_edges = true;
154 return prev;
155 }
156
157 void set_is_patched() {
158 _is_patched = true;
159 CDS_ONLY(_shared_path_index = -1); // Mark all shared classes in this module invisible.
160 }
161 bool is_patched() {
162 return _is_patched;
163 }
164
165 ModuleEntry* next() const {
166 return (ModuleEntry*)HashtableEntry<Symbol*, mtModule>::next();
167 }
168 ModuleEntry** next_addr() {
169 return (ModuleEntry**)HashtableEntry<Symbol*, mtModule>::next_addr();
170 }
171
172 // iteration support for readability
173 void module_reads_do(ModuleClosure* const f);
174
175 // Purge dead weak references out of reads list when any given class loader is unloaded.
176 void purge_reads();
177 void delete_reads();
178
179 // Special handling for unnamed module, one per class loader
180 static ModuleEntry* create_unnamed_module(ClassLoaderData* cld);
181 static ModuleEntry* create_boot_unnamed_module(ClassLoaderData* cld);
182 static ModuleEntry* new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld);
183 void delete_unnamed_module();
184
185 void print(outputStream* st = tty);
186 void verify();
187
188 CDS_ONLY(int shared_path_index() { return _shared_path_index;})
189
190 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
191 };
192
193 // Iterator interface
194 class ModuleClosure: public StackObj {
195 public:
196 virtual void do_module(ModuleEntry* module) = 0;
197 };
198
199
200 // The ModuleEntryTable is a Hashtable containing a list of all modules defined
201 // by a particular class loader. Each module is represented as a ModuleEntry node.
202 //
203 // Each ModuleEntryTable contains a _javabase_module field which allows for the
204 // creation of java.base's ModuleEntry very early in bootstrapping before the
205 // corresponding JVM_DefineModule call for java.base occurs during module system
206 // initialization. Setting up java.base's ModuleEntry early enables classes,
207 // loaded prior to the module system being initialized to be created with their
208 // PackageEntry node's correctly pointing at java.base's ModuleEntry. No class
209 // outside of java.base is allowed to be loaded pre-module system initialization.
210 //
211 // The ModuleEntryTable's lookup is lock free.
212 //
213 class ModuleEntryTable : public Hashtable<Symbol*, mtModule> {
214 friend class VMStructs;
215 public:
216 enum Constants {
217 _moduletable_entry_size = 109 // number of entries in module entry table
218 };
219
220 private:
221 static ModuleEntry* _javabase_module;
222
223 ModuleEntry* new_entry(unsigned int hash, Handle module_handle, bool is_open,
224 Symbol* name, Symbol* version, Symbol* location, ClassLoaderData* loader_data);
225 void add_entry(int index, ModuleEntry* new_entry);
226
227 int entry_size() const { return BasicHashtable<mtModule>::entry_size(); }
228
229 ModuleEntry** bucket_addr(int i) {
230 return (ModuleEntry**)Hashtable<Symbol*, mtModule>::bucket_addr(i);
231 }
232
233 static unsigned int compute_hash(Symbol* name) { return ((name == NULL) ? 0 : (unsigned int)(name->identity_hash())); }
234 int index_for(Symbol* name) const { return hash_to_index(compute_hash(name)); }
235
236 public:
237 ModuleEntryTable(int table_size);
238 ~ModuleEntryTable();
239
240 ModuleEntry* bucket(int i) {
241 return (ModuleEntry*)Hashtable<Symbol*, mtModule>::bucket(i);
242 }
243
244 // Create module in loader's module entry table. Assume Module_lock
245 // has been locked by caller.
246 ModuleEntry* locked_create_entry(Handle module_handle,
247 bool is_open,
248 Symbol* module_name,
249 Symbol* module_version,
250 Symbol* module_location,
251 ClassLoaderData* loader_data);
252
253 // Only lookup module within loader's module entry table. The table read is lock-free.
254 ModuleEntry* lookup_only(Symbol* name);
255
256 // purge dead weak references out of reads list
257 void purge_all_module_reads();
258
259 // Special handling for java.base
260 static ModuleEntry* javabase_moduleEntry() { return _javabase_module; }
261 static void set_javabase_moduleEntry(ModuleEntry* java_base) {
262 assert(_javabase_module == NULL, "_javabase_module is already defined");
263 _javabase_module = java_base;
264 }
265
266 static bool javabase_defined() { return ((_javabase_module != NULL) &&
267 (_javabase_module->module() != NULL)); }
268 static void finalize_javabase(Handle module_handle, Symbol* version, Symbol* location);
269 static void patch_javabase_entries(Handle module_handle);
270
271 void print(outputStream* st = tty);
272 void verify();
273 };
274
275 #endif // SHARE_CLASSFILE_MODULEENTRY_HPP