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