1 /*
2 * Copyright (c) 2018, 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_CLASSLOADERDATAGRAPH_HPP
26 #define SHARE_VM_CLASSFILE_CLASSLOADERDATAGRAPH_HPP
27
28 #include "classfile/classLoaderData.hpp"
29 #include "memory/allocation.hpp"
30 #include "utilities/growableArray.hpp"
31 #include "utilities/macros.hpp"
32
33 // GC root for walking class loader data created
34
35 class ClassLoaderDataGraph : public AllStatic {
36 friend class ClassLoaderData;
37 friend class ClassLoaderDataGraphMetaspaceIterator;
38 friend class ClassLoaderDataGraphKlassIteratorAtomic;
39 friend class ClassLoaderDataGraphKlassIteratorStatic;
40 friend class ClassLoaderDataGraphIterator;
41 friend class VMStructs;
42 private:
43 // All CLDs (except the null CLD) can be reached by walking _head->_next->...
44 static ClassLoaderData* _head;
45 static ClassLoaderData* _unloading;
46 // CMS support.
47 static ClassLoaderData* _saved_head;
48 static ClassLoaderData* _saved_unloading;
49 static bool _should_purge;
50
51 // Set if there's anything to purge in the deallocate lists or previous versions
52 // during a safepoint after class unloading in a full GC.
53 static bool _should_clean_deallocate_lists;
54 static bool _safepoint_cleanup_needed;
55
56 // OOM has been seen in metaspace allocation. Used to prevent some
57 // allocations until class unloading
58 static bool _metaspace_oom;
59
60 static volatile size_t _num_instance_classes;
61 static volatile size_t _num_array_classes;
62
63 static ClassLoaderData* add_to_graph(Handle class_loader, bool is_unsafe_anonymous);
64 static ClassLoaderData* add(Handle class_loader, bool is_unsafe_anonymous);
65
66 public:
67 static ClassLoaderData* find_or_create(Handle class_loader);
68 static void clean_module_and_package_info();
69 static void purge();
70 static void clear_claimed_marks();
71 // Iteration through CLDG inside a safepoint; GC support
72 static void cld_do(CLDClosure* cl);
73 static void cld_unloading_do(CLDClosure* cl);
74 static void roots_cld_do(CLDClosure* strong, CLDClosure* weak);
75 static void always_strong_cld_do(CLDClosure* cl);
76 // klass do
77 // Walking classes through the ClassLoaderDataGraph include array classes. It also includes
78 // classes that are allocated but not loaded, classes that have errors, and scratch classes
79 // for redefinition. These classes are removed during the next class unloading.
80 // Walking the ClassLoaderDataGraph also includes unsafe anonymous classes.
81 static void classes_do(KlassClosure* klass_closure);
82 static void classes_do(void f(Klass* const));
83 static void methods_do(void f(Method*));
84 static void modules_do(void f(ModuleEntry*));
85 static void modules_unloading_do(void f(ModuleEntry*));
86 static void packages_do(void f(PackageEntry*));
87 static void packages_unloading_do(void f(PackageEntry*));
88 static void loaded_classes_do(KlassClosure* klass_closure);
89 static void unlocked_loaded_classes_do(KlassClosure* klass_closure);
90 static void classes_unloading_do(void f(Klass* const));
91 static bool do_unloading(bool do_cleaning);
92
93 // Expose state to avoid logging overhead in safepoint cleanup tasks.
94 static inline bool should_clean_metaspaces_and_reset();
95 static void set_should_clean_deallocate_lists() { _should_clean_deallocate_lists = true; }
96 static void clean_deallocate_lists(bool purge_previous_versions);
97 static void walk_metadata_and_clean_metaspaces();
98
99 // dictionary do
100 // Iterate over all klasses in dictionary, but
101 // just the classes from defining class loaders.
102 static void dictionary_classes_do(void f(InstanceKlass*));
103 // Added for initialize_itable_for_klass to handle exceptions.
104 static void dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS);
105
106 // VM_CounterDecay iteration support
107 static InstanceKlass* try_get_next_class();
108 static void adjust_saved_class(ClassLoaderData* cld);
109 static void adjust_saved_class(Klass* klass);
110
111 static void verify_dictionary();
112 static void print_dictionary(outputStream* st);
113 static void print_dictionary_statistics(outputStream* st);
114
115 // CMS support.
116 static void remember_new_clds(bool remember) { _saved_head = (remember ? _head : NULL); }
117 static GrowableArray<ClassLoaderData*>* new_clds();
118
119 static void set_should_purge(bool b) { _should_purge = b; }
120 static void purge_if_needed() {
121 // Only purge the CLDG for CMS if concurrent sweep is complete.
122 if (_should_purge) {
123 purge();
124 // reset for next time.
125 set_should_purge(false);
126 }
127 }
128
129 static int resize_if_needed();
130
131 static bool has_metaspace_oom() { return _metaspace_oom; }
132 static void set_metaspace_oom(bool value) { _metaspace_oom = value; }
133
134 static void print_on(outputStream * const out) PRODUCT_RETURN;
135 static void print() { print_on(tty); }
136 static void verify();
137
138 // instance and array class counters
139 static inline size_t num_instance_classes();
140 static inline size_t num_array_classes();
141 static inline void inc_instance_classes(size_t count);
142 static inline void dec_instance_classes(size_t count);
143 static inline void inc_array_classes(size_t count);
144 static inline void dec_array_classes(size_t count);
145
146 #ifndef PRODUCT
147 static bool contains_loader_data(ClassLoaderData* loader_data);
148 #endif
149
150 // Check if ClassLoaderData is part of the ClassLoaderDataGraph (not unloaded)
151 // Usage without lock only allowed during error reporting.
152 static bool is_valid(ClassLoaderData* loader_data);
153 };
154
155 class LockedClassesDo : public KlassClosure {
156 typedef void (*classes_do_func_t)(Klass*);
157 classes_do_func_t _function;
158 public:
159 LockedClassesDo(); // For callers who provide their own do_klass
160 LockedClassesDo(classes_do_func_t function);
161 ~LockedClassesDo();
162
163 void do_klass(Klass* k) {
164 (*_function)(k);
165 }
166 };
167
168 // An iterator that distributes Klasses to parallel worker threads.
169 class ClassLoaderDataGraphKlassIteratorAtomic : public StackObj {
170 Klass* volatile _next_klass;
171 public:
172 ClassLoaderDataGraphKlassIteratorAtomic();
173 Klass* next_klass();
174 private:
175 static Klass* next_klass_in_cldg(Klass* klass);
176 };
177
178 class ClassLoaderDataGraphMetaspaceIterator : public StackObj {
179 ClassLoaderData* _data;
180 public:
181 ClassLoaderDataGraphMetaspaceIterator();
182 ~ClassLoaderDataGraphMetaspaceIterator();
183 bool repeat() { return _data != NULL; }
184 ClassLoaderMetaspace* get_next();
185 };
186 #endif // SHARE_VM_CLASSFILE_CLASSLOADERDATAGRAPH_HPP