1 /*
2 * Copyright (c) 1997, 2013, 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
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23 */
24
25 #ifndef SHARE_VM_MEMORY_ITERATOR_HPP
26 #define SHARE_VM_MEMORY_ITERATOR_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "utilities/top.hpp"
31
32 class CodeBlob;
33 class nmethod;
34 class ReferenceProcessor;
35 class DataLayout;
36 class KlassClosure;
37 class ClassLoaderData;
38
39 // The following classes are C++ `closures` for iterating over objects, roots and spaces
40
41 class Closure : public StackObj { };
42
43 // OopClosure is used for iterating through references to Java objects.
44 class OopClosure : public Closure {
45 public:
46 virtual void do_oop(oop* o) = 0;
47 virtual void do_oop_v(oop* o) { do_oop(o); }
48 virtual void do_oop(narrowOop* o) = 0;
49 virtual void do_oop_v(narrowOop* o) { do_oop(o); }
50 };
51
52 // ExtendedOopClosure adds extra code to be run during oop iterations.
53 // This is needed by the GC and is extracted to a separate type to not
54 // pollute the OopClosure interface.
55 class ExtendedOopClosure : public OopClosure {
56 public:
57 ReferenceProcessor* _ref_processor;
58 ExtendedOopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
59 ExtendedOopClosure() : OopClosure(), _ref_processor(NULL) { }
60
61 // If the do_metadata functions return "true",
62 // we invoke the following when running oop_iterate():
63 //
64 // 1) do_klass on the header klass pointer.
65 // 2) do_klass on the klass pointer in the mirrors.
66 // 3) do_class_loader_data on the class loader data in class loaders.
67 //
68 // The virtual (without suffix) and the non-virtual (with _nv suffix) need
69 // to be updated together, or else the devirtualization will break.
70 //
71 // Providing default implementations of the _nv functions unfortunately
72 // removes the compile-time safeness, but reduces the clutter for the
73 // ExtendedOopClosures that don't need to walk the metadata. Currently,
74 // only CMS needs these.
75
76 virtual bool do_metadata() { return do_metadata_nv(); }
77 bool do_metadata_v() { return do_metadata(); }
78 bool do_metadata_nv() { return false; }
79
80 virtual void do_klass(Klass* k) { do_klass_nv(k); }
81 void do_klass_v(Klass* k) { do_klass(k); }
82 void do_klass_nv(Klass* k) { ShouldNotReachHere(); }
83
84 virtual void do_class_loader_data(ClassLoaderData* cld) { ShouldNotReachHere(); }
85
86 // True iff this closure may be safely applied more than once to an oop
87 // location without an intervening "major reset" (like the end of a GC).
88 virtual bool idempotent() { return false; }
89 virtual bool apply_to_weak_ref_discovered_field() { return false; }
90 };
91
92 // Wrapper closure only used to implement oop_iterate_no_header().
93 class NoHeaderExtendedOopClosure : public ExtendedOopClosure {
94 OopClosure* _wrapped_closure;
95 public:
96 NoHeaderExtendedOopClosure(OopClosure* cl) : _wrapped_closure(cl) {}
97 // Warning: this calls the virtual version do_oop in the the wrapped closure.
98 void do_oop_nv(oop* p) { _wrapped_closure->do_oop(p); }
99 void do_oop_nv(narrowOop* p) { _wrapped_closure->do_oop(p); }
100
101 void do_oop(oop* p) { assert(false, "Only the _nv versions should be used");
102 _wrapped_closure->do_oop(p); }
103 void do_oop(narrowOop* p) { assert(false, "Only the _nv versions should be used");
104 _wrapped_closure->do_oop(p);}
105 };
106
107 class KlassClosure : public Closure {
108 public:
109 virtual void do_klass(Klass* k) = 0;
110 };
111
112 class CLDClosure : public Closure {
113 public:
114 virtual void do_cld(ClassLoaderData* cld) = 0;
115 };
116
117 class KlassToOopClosure : public KlassClosure {
118 friend class MetadataAwareOopClosure;
119 friend class MetadataAwareOopsInGenClosure;
120
121 OopClosure* _oop_closure;
122
123 // Used when _oop_closure couldn't be set in an initialization list.
124 void initialize(OopClosure* oop_closure) {
125 assert(_oop_closure == NULL, "Should only be called once");
126 _oop_closure = oop_closure;
127 }
128
129 public:
130 KlassToOopClosure(OopClosure* oop_closure = NULL) : _oop_closure(oop_closure) {}
131 virtual void do_klass(Klass* k);
132 };
133
134 class CLDToOopClosure : public CLDClosure {
135 OopClosure* _oop_closure;
136 KlassToOopClosure _klass_closure;
137 bool _must_claim_cld;
138
139 public:
140 CLDToOopClosure(OopClosure* oop_closure, bool must_claim_cld = true) :
141 _oop_closure(oop_closure),
142 _klass_closure(oop_closure),
143 _must_claim_cld(must_claim_cld) {}
144
145 void do_cld(ClassLoaderData* cld);
146 };
147
148 // The base class for all concurrent marking closures,
149 // that participates in class unloading.
150 // It's used to proxy through the metadata to the oops defined in them.
151 class MetadataAwareOopClosure: public ExtendedOopClosure {
152 KlassToOopClosure _klass_closure;
153
154 public:
155 MetadataAwareOopClosure() : ExtendedOopClosure() {
156 _klass_closure.initialize(this);
157 }
158 MetadataAwareOopClosure(ReferenceProcessor* rp) : ExtendedOopClosure(rp) {
159 _klass_closure.initialize(this);
160 }
161
162 virtual bool do_metadata() { return do_metadata_nv(); }
163 inline bool do_metadata_nv() { return true; }
164
165 virtual void do_klass(Klass* k);
166 void do_klass_nv(Klass* k);
167
168 virtual void do_class_loader_data(ClassLoaderData* cld);
169 };
170
171 // ObjectClosure is used for iterating through an object space
172
173 class ObjectClosure : public Closure {
174 public:
175 // Called for each object.
176 virtual void do_object(oop obj) = 0;
177 };
178
179
180 class BoolObjectClosure : public Closure {
181 public:
182 virtual bool do_object_b(oop obj) = 0;
183 };
184
185 // Applies an oop closure to all ref fields in objects iterated over in an
186 // object iteration.
187 class ObjectToOopClosure: public ObjectClosure {
188 ExtendedOopClosure* _cl;
189 public:
190 void do_object(oop obj);
191 ObjectToOopClosure(ExtendedOopClosure* cl) : _cl(cl) {}
192 };
193
194 // A version of ObjectClosure that is expected to be robust
195 // in the face of possibly uninitialized objects.
196 class ObjectClosureCareful : public ObjectClosure {
197 public:
198 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
199 virtual size_t do_object_careful(oop p) = 0;
200 };
201
202 // The following are used in CompactibleFreeListSpace and
203 // ConcurrentMarkSweepGeneration.
204
205 // Blk closure (abstract class)
206 class BlkClosure : public StackObj {
207 public:
208 virtual size_t do_blk(HeapWord* addr) = 0;
209 };
210
211 // A version of BlkClosure that is expected to be robust
212 // in the face of possibly uninitialized objects.
213 class BlkClosureCareful : public BlkClosure {
214 public:
215 size_t do_blk(HeapWord* addr) {
216 guarantee(false, "call do_blk_careful instead");
217 return 0;
218 }
219 virtual size_t do_blk_careful(HeapWord* addr) = 0;
220 };
221
222 // SpaceClosure is used for iterating over spaces
223
224 class Space;
225 class CompactibleSpace;
226
227 class SpaceClosure : public StackObj {
228 public:
229 // Called for each space
230 virtual void do_space(Space* s) = 0;
231 };
232
233 class CompactibleSpaceClosure : public StackObj {
234 public:
235 // Called for each compactible space
236 virtual void do_space(CompactibleSpace* s) = 0;
237 };
238
239
240 // CodeBlobClosure is used for iterating through code blobs
241 // in the code cache or on thread stacks
242
243 class CodeBlobClosure : public Closure {
244 public:
245 // Called for each code blob.
246 virtual void do_code_blob(CodeBlob* cb) = 0;
247 };
248
249
250 class MarkingCodeBlobClosure : public CodeBlobClosure {
251 public:
252 // Called for each code blob, but at most once per unique blob.
253 virtual void do_newly_marked_nmethod(nmethod* nm) = 0;
254
255 virtual void do_code_blob(CodeBlob* cb);
256 // = { if (!nmethod(cb)->test_set_oops_do_mark()) do_newly_marked_nmethod(cb); }
257
258 class MarkScope : public StackObj {
259 protected:
260 bool _active;
261 public:
262 MarkScope(bool activate = true);
263 // = { if (active) nmethod::oops_do_marking_prologue(); }
264 ~MarkScope();
265 // = { if (active) nmethod::oops_do_marking_epilogue(); }
266 };
267 };
268
269
270 // Applies an oop closure to all ref fields in code blobs
271 // iterated over in an object iteration.
272 class CodeBlobToOopClosure: public MarkingCodeBlobClosure {
273 OopClosure* _cl;
274 bool _do_marking;
275 public:
276 virtual void do_newly_marked_nmethod(nmethod* cb);
277 // = { cb->oops_do(_cl); }
278 virtual void do_code_blob(CodeBlob* cb);
279 // = { if (_do_marking) super::do_code_blob(cb); else cb->oops_do(_cl); }
280 CodeBlobToOopClosure(OopClosure* cl, bool do_marking)
281 : _cl(cl), _do_marking(do_marking) {}
282 };
283
284
285
286 // MonitorClosure is used for iterating over monitors in the monitors cache
287
288 class ObjectMonitor;
289
290 class MonitorClosure : public StackObj {
291 public:
292 // called for each monitor in cache
293 virtual void do_monitor(ObjectMonitor* m) = 0;
294 };
295
296 // A closure that is applied without any arguments.
297 class VoidClosure : public StackObj {
298 public:
299 // I would have liked to declare this a pure virtual, but that breaks
300 // in mysterious ways, for unknown reasons.
301 virtual void do_void();
302 };
303
304
305 // YieldClosure is intended for use by iteration loops
306 // to incrementalize their work, allowing interleaving
307 // of an interruptable task so as to allow other
308 // threads to run (which may not otherwise be able to access
309 // exclusive resources, for instance). Additionally, the
310 // closure also allows for aborting an ongoing iteration
311 // by means of checking the return value from the polling
312 // call.
313 class YieldClosure : public StackObj {
314 public:
315 virtual bool should_return() = 0;
316 };
317
318 // Abstract closure for serializing data (read or write).
319
320 class SerializeClosure : public Closure {
321 public:
322 // Return bool indicating whether closure implements read or write.
323 virtual bool reading() const = 0;
324
325 // Read/write the void pointer pointed to by p.
326 virtual void do_ptr(void** p) = 0;
327
328 // Read/write the region specified.
329 virtual void do_region(u_char* start, size_t size) = 0;
330
331 // Check/write the tag. If reading, then compare the tag against
332 // the passed in value and fail is they don't match. This allows
333 // for verification that sections of the serialized data are of the
334 // correct length.
335 virtual void do_tag(int tag) = 0;
336 };
337
338 class SymbolClosure : public StackObj {
339 public:
340 virtual void do_symbol(Symbol**) = 0;
341
342 // Clear LSB in symbol address; it can be set by CPSlot.
343 static Symbol* load_symbol(Symbol** p) {
344 return (Symbol*)(intptr_t(*p) & ~1);
345 }
346
347 // Store symbol, adjusting new pointer if the original pointer was adjusted
348 // (symbol references in constant pool slots have their LSB set to 1).
349 static void store_symbol(Symbol** p, Symbol* sym) {
350 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1));
351 }
352 };
353
354
355 // Helper defines for ExtendOopClosure
356
357 #define if_do_metadata_checked(closure, nv_suffix) \
358 /* Make sure the non-virtual and the virtual versions match. */ \
359 assert(closure->do_metadata##nv_suffix() == closure->do_metadata(), \
360 "Inconsistency in do_metadata"); \
361 if (closure->do_metadata##nv_suffix())
362
363 #define assert_should_ignore_metadata(closure, nv_suffix) \
364 assert(!closure->do_metadata##nv_suffix(), "Code to handle metadata is not implemented")
365
366 #endif // SHARE_VM_MEMORY_ITERATOR_HPP