Thu, 31 Mar 2016 14:23:12 -0700
Merge
1 /*
2 * Copyright (c) 2012, 2014, 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 */
25 #ifndef SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP
26 #define SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "memory/metaspace.hpp"
31 #include "memory/metaspaceCounters.hpp"
32 #include "runtime/mutex.hpp"
33 #include "utilities/growableArray.hpp"
34 #include "utilities/macros.hpp"
35 #if INCLUDE_TRACE
36 #include "utilities/ticks.hpp"
37 #endif
39 //
40 // A class loader represents a linkset. Conceptually, a linkset identifies
41 // the complete transitive closure of resolved links that a dynamic linker can
42 // produce.
43 //
44 // A ClassLoaderData also encapsulates the allocation space, called a metaspace,
45 // used by the dynamic linker to allocate the runtime representation of all
46 // the types it defines.
47 //
48 // ClassLoaderData are stored in the runtime representation of classes and the
49 // system dictionary, are roots of garbage collection, and provides iterators
50 // for root tracing and other GC operations.
52 class ClassLoaderData;
53 class JNIMethodBlock;
54 class JNIHandleBlock;
55 class Metadebug;
57 // GC root for walking class loader data created
59 class ClassLoaderDataGraph : public AllStatic {
60 friend class ClassLoaderData;
61 friend class ClassLoaderDataGraphMetaspaceIterator;
62 friend class ClassLoaderDataGraphKlassIteratorAtomic;
63 friend class VMStructs;
64 private:
65 // All CLDs (except the null CLD) can be reached by walking _head->_next->...
66 static ClassLoaderData* _head;
67 static ClassLoaderData* _unloading;
68 // CMS support.
69 static ClassLoaderData* _saved_head;
70 static ClassLoaderData* _saved_unloading;
71 static bool _should_purge;
73 static ClassLoaderData* add(Handle class_loader, bool anonymous, TRAPS);
74 static void post_class_unload_events(void);
75 static void clean_metaspaces();
76 public:
77 static ClassLoaderData* find_or_create(Handle class_loader, TRAPS);
78 static void purge();
79 static void clear_claimed_marks();
80 // oops do
81 static void oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim);
82 static void keep_alive_oops_do(OopClosure* blk, KlassClosure* klass_closure, bool must_claim);
83 static void always_strong_oops_do(OopClosure* blk, KlassClosure* klass_closure, bool must_claim);
84 // cld do
85 static void cld_do(CLDClosure* cl);
86 static void roots_cld_do(CLDClosure* strong, CLDClosure* weak);
87 static void keep_alive_cld_do(CLDClosure* cl);
88 static void always_strong_cld_do(CLDClosure* cl);
89 // klass do
90 static void classes_do(KlassClosure* klass_closure);
91 static void classes_do(void f(Klass* const));
92 static void loaded_classes_do(KlassClosure* klass_closure);
93 static void classes_unloading_do(void f(Klass* const));
94 static bool do_unloading(BoolObjectClosure* is_alive, bool clean_alive);
96 // CMS support.
97 static void remember_new_clds(bool remember) { _saved_head = (remember ? _head : NULL); }
98 static GrowableArray<ClassLoaderData*>* new_clds();
100 static void set_should_purge(bool b) { _should_purge = b; }
101 static void purge_if_needed() {
102 // Only purge the CLDG for CMS if concurrent sweep is complete.
103 if (_should_purge) {
104 purge();
105 // reset for next time.
106 set_should_purge(false);
107 }
108 }
110 static void free_deallocate_lists();
112 static void dump_on(outputStream * const out) PRODUCT_RETURN;
113 static void dump() { dump_on(tty); }
114 static void verify();
116 static bool unload_list_contains(const void* x);
117 #ifndef PRODUCT
118 static bool contains_loader_data(ClassLoaderData* loader_data);
119 #endif
121 #if INCLUDE_TRACE
122 private:
123 static Ticks _class_unload_time;
124 static void class_unload_event(Klass* const k);
125 #endif
126 };
128 // ClassLoaderData class
130 class ClassLoaderData : public CHeapObj<mtClass> {
131 friend class VMStructs;
132 private:
133 class Dependencies VALUE_OBJ_CLASS_SPEC {
134 objArrayOop _list_head;
135 void locked_add(objArrayHandle last,
136 objArrayHandle new_dependency,
137 Thread* THREAD);
138 public:
139 Dependencies() : _list_head(NULL) {}
140 Dependencies(TRAPS) : _list_head(NULL) {
141 init(CHECK);
142 }
143 void add(Handle dependency, TRAPS);
144 void init(TRAPS);
145 void oops_do(OopClosure* f);
146 };
148 friend class ClassLoaderDataGraph;
149 friend class ClassLoaderDataGraphKlassIteratorAtomic;
150 friend class ClassLoaderDataGraphMetaspaceIterator;
151 friend class MetaDataFactory;
152 friend class Method;
154 static ClassLoaderData * _the_null_class_loader_data;
156 oop _class_loader; // oop used to uniquely identify a class loader
157 // class loader or a canonical class path
158 Dependencies _dependencies; // holds dependencies from this class loader
159 // data to others.
161 Metaspace * _metaspace; // Meta-space where meta-data defined by the
162 // classes in the class loader are allocated.
163 Mutex* _metaspace_lock; // Locks the metaspace for allocations and setup.
164 bool _unloading; // true if this class loader goes away
165 bool _keep_alive; // if this CLD is kept alive without a keep_alive_object().
166 bool _is_anonymous; // if this CLD is for an anonymous class
167 volatile int _claimed; // true if claimed, for example during GC traces.
168 // To avoid applying oop closure more than once.
169 // Has to be an int because we cas it.
170 Klass* _klasses; // The classes defined by the class loader.
172 JNIHandleBlock* _handles; // Handles to constant pool arrays
174 // These method IDs are created for the class loader and set to NULL when the
175 // class loader is unloaded. They are rarely freed, only for redefine classes
176 // and if they lose a data race in InstanceKlass.
177 JNIMethodBlock* _jmethod_ids;
179 // Metadata to be deallocated when it's safe at class unloading, when
180 // this class loader isn't unloaded itself.
181 GrowableArray<Metadata*>* _deallocate_list;
183 // Support for walking class loader data objects
184 ClassLoaderData* _next; /// Next loader_datas created
186 // ReadOnly and ReadWrite metaspaces (static because only on the null
187 // class loader for now).
188 static Metaspace* _ro_metaspace;
189 static Metaspace* _rw_metaspace;
191 void set_next(ClassLoaderData* next) { _next = next; }
192 ClassLoaderData* next() const { return _next; }
194 ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies);
195 ~ClassLoaderData();
197 void set_metaspace(Metaspace* m) { _metaspace = m; }
199 JNIHandleBlock* handles() const;
200 void set_handles(JNIHandleBlock* handles);
202 Mutex* metaspace_lock() const { return _metaspace_lock; }
204 // GC interface.
205 void clear_claimed() { _claimed = 0; }
206 bool claimed() const { return _claimed == 1; }
207 bool claim();
209 void unload();
210 bool keep_alive() const { return _keep_alive; }
211 void classes_do(void f(Klass*));
212 void loaded_classes_do(KlassClosure* klass_closure);
213 void classes_do(void f(InstanceKlass*));
215 // Deallocate free list during class unloading.
216 void free_deallocate_list();
218 // Allocate out of this class loader data
219 MetaWord* allocate(size_t size);
221 public:
223 bool is_alive(BoolObjectClosure* is_alive_closure) const;
225 // Accessors
226 Metaspace* metaspace_or_null() const { return _metaspace; }
228 static ClassLoaderData* the_null_class_loader_data() {
229 return _the_null_class_loader_data;
230 }
232 bool is_anonymous() const { return _is_anonymous; }
234 static void init_null_class_loader_data() {
235 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
236 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
238 // We explicitly initialize the Dependencies object at a later phase in the initialization
239 _the_null_class_loader_data = new ClassLoaderData((oop)NULL, false, Dependencies());
240 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
241 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
242 if (DumpSharedSpaces) {
243 _the_null_class_loader_data->initialize_shared_metaspaces();
244 }
245 }
247 bool is_the_null_class_loader_data() const {
248 return this == _the_null_class_loader_data;
249 }
250 bool is_ext_class_loader_data() const;
252 // The Metaspace is created lazily so may be NULL. This
253 // method will allocate a Metaspace if needed.
254 Metaspace* metaspace_non_null();
256 oop class_loader() const { return _class_loader; }
258 // The object the GC is using to keep this ClassLoaderData alive.
259 oop keep_alive_object() const;
261 // Returns true if this class loader data is for a loader going away.
262 bool is_unloading() const {
263 assert(!(is_the_null_class_loader_data() && _unloading), "The null class loader can never be unloaded");
264 return _unloading;
265 }
267 // Used to make sure that this CLD is not unloaded.
268 void set_keep_alive(bool value) { _keep_alive = value; }
270 unsigned int identity_hash() {
271 return _class_loader == NULL ? 0 : _class_loader->identity_hash();
272 }
274 // Used when tracing from klasses.
275 void oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim);
277 void classes_do(KlassClosure* klass_closure);
279 JNIMethodBlock* jmethod_ids() const { return _jmethod_ids; }
280 void set_jmethod_ids(JNIMethodBlock* new_block) { _jmethod_ids = new_block; }
282 void print_value() { print_value_on(tty); }
283 void print_value_on(outputStream* out) const;
284 void dump(outputStream * const out) PRODUCT_RETURN;
285 void verify();
286 const char* loader_name();
288 jobject add_handle(Handle h);
289 void add_class(Klass* k);
290 void remove_class(Klass* k);
291 bool contains_klass(Klass* k);
292 void record_dependency(Klass* to, TRAPS);
293 void init_dependencies(TRAPS);
295 void add_to_deallocate_list(Metadata* m);
297 static ClassLoaderData* class_loader_data(oop loader);
298 static ClassLoaderData* class_loader_data_or_null(oop loader);
299 static ClassLoaderData* anonymous_class_loader_data(oop loader, TRAPS);
300 static void print_loader(ClassLoaderData *loader_data, outputStream *out);
302 // CDS support
303 Metaspace* ro_metaspace();
304 Metaspace* rw_metaspace();
305 void initialize_shared_metaspaces();
306 };
308 // An iterator that distributes Klasses to parallel worker threads.
309 class ClassLoaderDataGraphKlassIteratorAtomic : public StackObj {
310 Klass* volatile _next_klass;
311 public:
312 ClassLoaderDataGraphKlassIteratorAtomic();
313 Klass* next_klass();
314 private:
315 static Klass* next_klass_in_cldg(Klass* klass);
316 };
318 class ClassLoaderDataGraphMetaspaceIterator : public StackObj {
319 ClassLoaderData* _data;
320 public:
321 ClassLoaderDataGraphMetaspaceIterator();
322 ~ClassLoaderDataGraphMetaspaceIterator();
323 bool repeat() { return _data != NULL; }
324 Metaspace* get_next() {
325 assert(_data != NULL, "Should not be NULL in call to the iterator");
326 Metaspace* result = _data->metaspace_or_null();
327 _data = _data->next();
328 // This result might be NULL for class loaders without metaspace
329 // yet. It would be nice to return only non-null results but
330 // there is no guarantee that there will be a non-null result
331 // down the list so the caller is going to have to check.
332 return result;
333 }
334 };
335 #endif // SHARE_VM_CLASSFILE_CLASSLOADERDATA_HPP