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); 103 104 bool can_read(ModuleEntry* m) const; 105 bool has_reads() const; 106 void add_read(ModuleEntry* m); 107 void set_read_walk_required(ClassLoaderData* m_loader_data); 108 109 bool is_named() const { return (name() != NULL); } 110 111 bool can_read_all_unnamed() const { 112 assert(is_named() || _can_read_all_unnamed == true, 113 "unnamed modules can always read all unnamed modules"); 114 return _can_read_all_unnamed; 115 } 116 117 // Modules can only go from strict to loose. 118 void set_can_read_all_unnamed() { _can_read_all_unnamed = true; } 119 120 bool has_default_read_edges() const { 121 return _has_default_read_edges; 122 } 123 124 // Sets true and returns the previous value. 125 bool set_has_default_read_edges() { 126 MutexLocker ml(Module_lock); 127 bool prev = _has_default_read_edges; 128 _has_default_read_edges = true; 129 return prev; 130 } 131 132 ModuleEntry* next() const { 133 return (ModuleEntry*)HashtableEntry<Symbol*, mtModule>::next(); 134 } 135 ModuleEntry** next_addr() { 136 return (ModuleEntry**)HashtableEntry<Symbol*, mtModule>::next_addr(); 137 } 138 139 // iteration support for readability 140 void module_reads_do(ModuleClosure* const f); 141 142 TRACE_DEFINE_TRACE_ID_METHODS; 143 144 // Purge dead weak references out of reads list when any given class loader is unloaded. 145 void purge_reads(); 146 void delete_reads(); 147 148 void print(outputStream* st = tty); 149 void verify(); 150 }; 151 152 // Iterator interface 153 class ModuleClosure: public StackObj { 154 public: 155 virtual void do_module(ModuleEntry* const module) = 0; 156 }; 157 158 159 // The ModuleEntryTable is a Hashtable containing a list of all modules defined 160 // by a particular class loader. Each module is represented as a ModuleEntry node. 161 // 162 // Each ModuleEntryTable contains a _javabase_module field which allows for the 163 // creation of java.base's ModuleEntry very early in bootstrapping before the 164 // corresponding JVM_DefineModule call for java.base occurs during module system 165 // initialization. Setting up java.base's ModuleEntry early enables classes, 166 // loaded prior to the module system being initialized to be created with their 167 // PackageEntry node's correctly pointing at java.base's ModuleEntry. No class 168 // outside of java.base is allowed to be loaded pre-module system initialization. 169 // 170 // The ModuleEntryTable's lookup is lock free. 171 // 172 class ModuleEntryTable : public Hashtable<Symbol*, mtModule> { 173 friend class VMStructs; 174 public: 175 enum Constants { 176 _moduletable_entry_size = 109 // number of entries in module entry table 177 }; 178 179 private: 180 static ModuleEntry* _javabase_module; 181 ModuleEntry* _unnamed_module; 182 183 ModuleEntry* new_entry(unsigned int hash, Handle module_handle, Symbol* name, Symbol* version, 184 Symbol* location, ClassLoaderData* loader_data); 185 void add_entry(int index, ModuleEntry* new_entry); 186 187 int entry_size() const { return BasicHashtable<mtModule>::entry_size(); } 188 189 ModuleEntry** bucket_addr(int i) { 190 return (ModuleEntry**)Hashtable<Symbol*, mtModule>::bucket_addr(i); 191 } 192 193 static unsigned int compute_hash(Symbol* name) { return ((name == NULL) ? 0 : (unsigned int)(name->identity_hash())); } 194 int index_for(Symbol* name) const { return hash_to_index(compute_hash(name)); } 195 196 public: 197 ModuleEntryTable(int table_size); 198 ~ModuleEntryTable(); 199 200 ModuleEntry* bucket(int i) { 201 return (ModuleEntry*)Hashtable<Symbol*, mtModule>::bucket(i); 202 } 203 204 // Create module in loader's module entry table, if already exists then 205 // return null. Assume Module_lock has been locked by caller. 206 ModuleEntry* locked_create_entry_or_null(Handle module_handle, 207 Symbol* module_name, 208 Symbol* module_version, 209 Symbol* module_location, 210 ClassLoaderData* loader_data); 211 212 // Only lookup module within loader's module entry table. The table read is lock-free. 213 ModuleEntry* lookup_only(Symbol* name); 214 215 // purge dead weak references out of reads list 216 void purge_all_module_reads(); 217 218 // Special handling for unnamed module, one per class loader's ModuleEntryTable 219 void create_unnamed_module(ClassLoaderData* loader_data); 220 ModuleEntry* unnamed_module() { return _unnamed_module; } 221 222 // Special handling for java.base 223 static ModuleEntry* javabase_moduleEntry() { return _javabase_module; } 224 static void set_javabase_moduleEntry(ModuleEntry* java_base) { _javabase_module = java_base; } 225 static bool javabase_defined() { return ((_javabase_module != NULL) && 226 (_javabase_module->module() != NULL)); } 227 static void finalize_javabase(Handle module_handle, Symbol* version, Symbol* location); 228 static void patch_javabase_entries(Handle module_handle); 229 230 void print(outputStream* st = tty); 231 void verify(); 232 }; 233 234 #endif // SHARE_VM_CLASSFILE_MODULEENTRY_HPP