1 /*
2 * Copyright (c) 1997, 2021, 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_MEMORY_ITERATOR_HPP
26 #define SHARE_MEMORY_ITERATOR_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/oopsHierarchy.hpp"
31
32 class CodeBlob;
33 class nmethod;
34 class ReferenceDiscoverer;
35 class DataLayout;
36 class KlassClosure;
37 class ClassLoaderData;
38 class Symbol;
39 class Metadata;
40 class Thread;
41
42 // The following classes are C++ `closures` for iterating over objects, roots and spaces
43
44 class Closure : public StackObj { };
45
46 // Thread iterator
47 class ThreadClosure {
48 public:
49 virtual void do_thread(Thread* thread) = 0;
50 };
51
52 // OopClosure is used for iterating through references to Java objects.
53 class OopClosure : public Closure {
54 public:
55 virtual void do_oop(oop* o) = 0;
56 virtual void do_oop(narrowOop* o) = 0;
57 virtual void do_oop_no_buffering(oop* o) { do_oop(o); }
58 virtual void do_oop_no_buffering(narrowOop* o) { do_oop(o); }
59 };
60
61 class DoNothingClosure : public OopClosure {
62 public:
63 virtual void do_oop(oop* p) {}
64 virtual void do_oop(narrowOop* p) {}
65 };
66 extern DoNothingClosure do_nothing_cl;
67
68 // OopIterateClosure adds extra code to be run during oop iterations.
69 // This is needed by the GC and is extracted to a separate type to not
70 // pollute the OopClosure interface.
71 class OopIterateClosure : public OopClosure {
72 private:
73 ReferenceDiscoverer* _ref_discoverer;
74
75 protected:
76 OopIterateClosure(ReferenceDiscoverer* rd) : _ref_discoverer(rd) { }
77 OopIterateClosure() : _ref_discoverer(NULL) { }
78 ~OopIterateClosure() { }
79
80 void set_ref_discoverer_internal(ReferenceDiscoverer* rd) { _ref_discoverer = rd; }
81
82 public:
83 ReferenceDiscoverer* ref_discoverer() const { return _ref_discoverer; }
84
85 // Iteration of InstanceRefKlasses differ depending on the closure,
86 // the below enum describes the different alternatives.
87 enum ReferenceIterationMode {
88 DO_DISCOVERY, // Apply closure and discover references
89 DO_DISCOVERED_AND_DISCOVERY, // Apply closure to discovered field and do discovery
90 DO_FIELDS, // Apply closure to all fields
91 DO_FIELDS_EXCEPT_REFERENT // Apply closure to all fields except the referent field
92 };
93
94 // The default iteration mode is to do discovery.
95 virtual ReferenceIterationMode reference_iteration_mode() { return DO_DISCOVERY; }
96
97 // If the do_metadata functions return "true",
98 // we invoke the following when running oop_iterate():
99 //
100 // 1) do_klass on the header klass pointer.
101 // 2) do_klass on the klass pointer in the mirrors.
102 // 3) do_cld on the class loader data in class loaders.
103
104 virtual bool do_metadata() = 0;
105 virtual void do_klass(Klass* k) = 0;
106 virtual void do_cld(ClassLoaderData* cld) = 0;
107 };
108
109 // An OopIterateClosure that can be used when there's no need to visit the Metadata.
110 class BasicOopIterateClosure : public OopIterateClosure {
111 public:
112 BasicOopIterateClosure(ReferenceDiscoverer* rd = NULL) : OopIterateClosure(rd) {}
113
114 virtual bool do_metadata() { return false; }
115 virtual void do_klass(Klass* k) { ShouldNotReachHere(); }
116 virtual void do_cld(ClassLoaderData* cld) { ShouldNotReachHere(); }
117 };
118
119 class BufferedValueClosure : public Closure {
120 public:
121 virtual void do_buffered_value(oop* p) = 0;
122 };
123
124 class KlassClosure : public Closure {
125 public:
126 virtual void do_klass(Klass* k) = 0;
127 };
128
129 class CLDClosure : public Closure {
130 public:
131 virtual void do_cld(ClassLoaderData* cld) = 0;
132 };
133
134 class MetadataClosure : public Closure {
135 public:
136 virtual void do_metadata(Metadata* md) = 0;
137 };
138
139
140 class CLDToOopClosure : public CLDClosure {
141 OopClosure* _oop_closure;
142 int _cld_claim;
143
144 public:
145 CLDToOopClosure(OopClosure* oop_closure,
146 int cld_claim) :
147 _oop_closure(oop_closure),
148 _cld_claim(cld_claim) {}
149
150 void do_cld(ClassLoaderData* cld);
151 };
152
153 template <int claim>
154 class ClaimingCLDToOopClosure : public CLDToOopClosure {
155 public:
156 ClaimingCLDToOopClosure(OopClosure* cl) : CLDToOopClosure(cl, claim) {}
157 };
158
159 class ClaimMetadataVisitingOopIterateClosure : public OopIterateClosure {
160 protected:
161 const int _claim;
162
163 public:
164 ClaimMetadataVisitingOopIterateClosure(int claim, ReferenceDiscoverer* rd = NULL) :
165 OopIterateClosure(rd),
166 _claim(claim) { }
167
168 virtual bool do_metadata() { return true; }
169 virtual void do_klass(Klass* k);
170 virtual void do_cld(ClassLoaderData* cld);
171 };
172
173 // The base class for all concurrent marking closures,
174 // that participates in class unloading.
175 // It's used to proxy through the metadata to the oops defined in them.
176 class MetadataVisitingOopIterateClosure: public ClaimMetadataVisitingOopIterateClosure {
177 public:
178 MetadataVisitingOopIterateClosure(ReferenceDiscoverer* rd = NULL);
179 };
180
181 // ObjectClosure is used for iterating through an object space
182
183 class ObjectClosure : public Closure {
184 public:
185 // Called for each object.
186 virtual void do_object(oop obj) = 0;
187 };
188
189
190 class BoolObjectClosure : public Closure {
191 public:
192 virtual bool do_object_b(oop obj) = 0;
193 };
194
195 class AlwaysTrueClosure: public BoolObjectClosure {
196 public:
197 bool do_object_b(oop p) { return true; }
198 };
199
200 class AlwaysFalseClosure : public BoolObjectClosure {
201 public:
202 bool do_object_b(oop p) { return false; }
203 };
204
205 // Applies an oop closure to all ref fields in objects iterated over in an
206 // object iteration.
207 class ObjectToOopClosure: public ObjectClosure {
208 OopIterateClosure* _cl;
209 public:
210 void do_object(oop obj);
211 ObjectToOopClosure(OopIterateClosure* cl) : _cl(cl) {}
212 };
213
214 // SpaceClosure is used for iterating over spaces
215
216 class Space;
217 class CompactibleSpace;
218
219 class SpaceClosure : public StackObj {
220 public:
221 // Called for each space
222 virtual void do_space(Space* s) = 0;
223 };
224
225 class CompactibleSpaceClosure : public StackObj {
226 public:
227 // Called for each compactible space
228 virtual void do_space(CompactibleSpace* s) = 0;
229 };
230
231
232 // CodeBlobClosure is used for iterating through code blobs
233 // in the code cache or on thread stacks
234
235 class CodeBlobClosure : public Closure {
236 public:
237 // Called for each code blob.
238 virtual void do_code_blob(CodeBlob* cb) = 0;
239 };
240
241 // Applies an oop closure to all ref fields in code blobs
242 // iterated over in an object iteration.
243 class CodeBlobToOopClosure : public CodeBlobClosure {
244 OopClosure* _cl;
245 bool _fix_relocations;
246 protected:
247 void do_nmethod(nmethod* nm);
248 public:
249 // If fix_relocations(), then cl must copy objects to their new location immediately to avoid
250 // patching nmethods with the old locations.
251 CodeBlobToOopClosure(OopClosure* cl, bool fix_relocations) : _cl(cl), _fix_relocations(fix_relocations) {}
252 virtual void do_code_blob(CodeBlob* cb);
253
254 bool fix_relocations() const { return _fix_relocations; }
255 const static bool FixRelocations = true;
256 };
257
258 class MarkingCodeBlobClosure : public CodeBlobToOopClosure {
259 public:
260 MarkingCodeBlobClosure(OopClosure* cl, bool fix_relocations) : CodeBlobToOopClosure(cl, fix_relocations) {}
261 // Called for each code blob, but at most once per unique blob.
262
263 virtual void do_code_blob(CodeBlob* cb);
264 };
265
266 class NMethodClosure : public Closure {
267 public:
268 virtual void do_nmethod(nmethod* n) = 0;
269 };
270
271 class CodeBlobToNMethodClosure : public CodeBlobClosure {
272 NMethodClosure* const _nm_cl;
273
274 public:
275 CodeBlobToNMethodClosure(NMethodClosure* nm_cl) : _nm_cl(nm_cl) {}
276
277 virtual void do_code_blob(CodeBlob* cb);
278 };
279
280 // MonitorClosure is used for iterating over monitors in the monitors cache
281
282 class ObjectMonitor;
283
284 class MonitorClosure : public StackObj {
285 public:
286 // called for each monitor in cache
287 virtual void do_monitor(ObjectMonitor* m) = 0;
288 };
289
290 // A closure that is applied without any arguments.
291 class VoidClosure : public StackObj {
292 public:
293 virtual void do_void() = 0;
294 };
295
296
297 // YieldClosure is intended for use by iteration loops
298 // to incrementalize their work, allowing interleaving
299 // of an interruptable task so as to allow other
300 // threads to run (which may not otherwise be able to access
301 // exclusive resources, for instance). Additionally, the
302 // closure also allows for aborting an ongoing iteration
303 // by means of checking the return value from the polling
304 // call.
305 class YieldClosure : public StackObj {
306 public:
307 virtual bool should_return() = 0;
308
309 // Yield on a fine-grain level. The check in case of not yielding should be very fast.
310 virtual bool should_return_fine_grain() { return false; }
311 };
312
313 // Abstract closure for serializing data (read or write).
314
315 class SerializeClosure : public Closure {
316 public:
317 // Return bool indicating whether closure implements read or write.
318 virtual bool reading() const = 0;
319
320 // Read/write the void pointer pointed to by p.
321 virtual void do_ptr(void** p) = 0;
322
323 // Read/write the 32-bit unsigned integer pointed to by p.
324 virtual void do_u4(u4* p) = 0;
325
326 // Read/write the bool pointed to by p.
327 virtual void do_bool(bool* p) = 0;
328
329 // Read/write the region specified.
330 virtual void do_region(u_char* start, size_t size) = 0;
331
332 // Check/write the tag. If reading, then compare the tag against
333 // the passed in value and fail is they don't match. This allows
334 // for verification that sections of the serialized data are of the
335 // correct length.
336 virtual void do_tag(int tag) = 0;
337
338 // Read/write the oop
339 virtual void do_oop(oop* o) = 0;
340
341 bool writing() {
342 return !reading();
343 }
344 };
345
346 class SymbolClosure : public StackObj {
347 public:
348 virtual void do_symbol(Symbol**) = 0;
349 };
350
351 template <typename E>
352 class CompareClosure : public Closure {
353 public:
354 virtual int do_compare(const E&, const E&) = 0;
355 };
356
357 // Dispatches to the non-virtual functions if OopClosureType has
358 // a concrete implementation, otherwise a virtual call is taken.
359 class Devirtualizer {
360 public:
361 template <typename OopClosureType, typename T> static void do_oop(OopClosureType* closure, T* p);
362 template <typename OopClosureType> static void do_klass(OopClosureType* closure, Klass* k);
363 template <typename OopClosureType> static void do_cld(OopClosureType* closure, ClassLoaderData* cld);
364 template <typename OopClosureType> static bool do_metadata(OopClosureType* closure);
365 };
366
367 class OopIteratorClosureDispatch {
368 public:
369 template <typename OopClosureType> static void oop_oop_iterate(OopClosureType* cl, oop obj, Klass* klass);
370 template <typename OopClosureType> static void oop_oop_iterate(OopClosureType* cl, oop obj, Klass* klass, MemRegion mr);
371 template <typename OopClosureType> static void oop_oop_iterate_backwards(OopClosureType* cl, oop obj, Klass* klass);
372 };
373
374 #endif // SHARE_MEMORY_ITERATOR_HPP