1 #ifdef USE_PRAGMA_IDENT_HDR
2 #pragma ident "@(#)iterator.hpp 1.38 07/05/05 17:05:52 JVM"
3 #endif
4 /*
5 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
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25 *
26 */
27
28 // The following classes are C++ `closures` for iterating over objects, roots and spaces
29
30 class ReferenceProcessor;
31
32 // Closure provides abortability.
33
34 class Closure : public StackObj {
35 protected:
36 bool _abort;
37 void set_abort() { _abort = true; }
38 public:
39 Closure() : _abort(false) {}
40 // A subtype can use this mechanism to indicate to some iterator mapping
41 // functions that the iteration should cease.
42 bool abort() { return _abort; }
43 void clear_abort() { _abort = false; }
44 };
45
46 // OopClosure is used for iterating through roots (oop*)
47
48 class OopClosure : public Closure {
49 public:
50 ReferenceProcessor* _ref_processor;
51 OopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
52 OopClosure() : _ref_processor(NULL) { }
53 virtual void do_oop(oop* o) = 0;
54 virtual void do_oop_v(oop* o) { do_oop(o); }
55 virtual void do_oop(narrowOop* o) = 0;
56 virtual void do_oop_v(narrowOop* o) { do_oop(o); }
57
58 // In support of post-processing of weak links of KlassKlass objects;
59 // see KlassKlass::oop_oop_iterate().
60 virtual const bool should_remember_klasses() const { return false; }
61 virtual void remember_klass(Klass* k) { /* do nothing */ }
62
63 // If "true", invoke on nmethods (when scanning compiled frames).
64 virtual const bool do_nmethods() const { return false; }
65
66 // The methods below control how object iterations invoking this closure
67 // should be performed:
68
69 // If "true", invoke on header klass field.
70 bool do_header() { return true; } // Note that this is non-virtual.
71 // Controls how prefetching is done for invocations of this closure.
72 Prefetch::style prefetch_style() { // Note that this is non-virtual.
73 return Prefetch::do_none;
74 }
75
76 // True iff this closure may be safely applied more than once to an oop
77 // location without an intervening "major reset" (like the end of a GC).
78 virtual bool idempotent() { return false; }
79 virtual bool apply_to_weak_ref_discovered_field() { return false; }
80 };
81
82 // ObjectClosure is used for iterating through an object space
83
84 class ObjectClosure : public Closure {
85 public:
86 // Called for each object.
87 virtual void do_object(oop obj) = 0;
88 };
89
90
91 class BoolObjectClosure : public ObjectClosure {
92 public:
93 virtual bool do_object_b(oop obj) = 0;
94 };
95
96 // Applies an oop closure to all ref fields in objects iterated over in an
97 // object iteration.
98 class ObjectToOopClosure: public ObjectClosure {
99 OopClosure* _cl;
100 public:
101 void do_object(oop obj);
102 ObjectToOopClosure(OopClosure* cl) : _cl(cl) {}
103 };
104
105 // A version of ObjectClosure with "memory" (see _previous_address below)
106 class UpwardsObjectClosure: public BoolObjectClosure {
107 HeapWord* _previous_address;
108 public:
109 UpwardsObjectClosure() : _previous_address(NULL) { }
110 void set_previous(HeapWord* addr) { _previous_address = addr; }
111 HeapWord* previous() { return _previous_address; }
112 // A return value of "true" can be used by the caller to decide
113 // if this object's end should *NOT* be recorded in
114 // _previous_address above.
115 virtual bool do_object_bm(oop obj, MemRegion mr) = 0;
116 };
117
118 // A version of ObjectClosure that is expected to be robust
119 // in the face of possibly uninitialized objects.
120 class ObjectClosureCareful : public ObjectClosure {
121 public:
122 virtual size_t do_object_careful_m(oop p, MemRegion mr) = 0;
123 virtual size_t do_object_careful(oop p) = 0;
124 };
125
126 // The following are used in CompactibleFreeListSpace and
127 // ConcurrentMarkSweepGeneration.
128
129 // Blk closure (abstract class)
130 class BlkClosure : public StackObj {
131 public:
132 virtual size_t do_blk(HeapWord* addr) = 0;
133 };
134
135 // A version of BlkClosure that is expected to be robust
136 // in the face of possibly uninitialized objects.
137 class BlkClosureCareful : public BlkClosure {
138 public:
139 size_t do_blk(HeapWord* addr) {
140 guarantee(false, "call do_blk_careful instead");
141 return 0;
142 }
143 virtual size_t do_blk_careful(HeapWord* addr) = 0;
144 };
145
146 // SpaceClosure is used for iterating over spaces
147
148 class Space;
149 class CompactibleSpace;
150
151 class SpaceClosure : public StackObj {
152 public:
153 // Called for each space
154 virtual void do_space(Space* s) = 0;
155 };
156
157 class CompactibleSpaceClosure : public StackObj {
158 public:
159 // Called for each compactible space
160 virtual void do_space(CompactibleSpace* s) = 0;
161 };
162
163
164
165 // MonitorClosure is used for iterating over monitors in the monitors cache
166
167 class ObjectMonitor;
168
169 class MonitorClosure : public StackObj {
170 public:
171 // called for each monitor in cache
172 virtual void do_monitor(ObjectMonitor* m) = 0;
173 };
174
175 // A closure that is applied without any arguments.
176 class VoidClosure : public StackObj {
177 public:
178 // I would have liked to declare this a pure virtual, but that breaks
179 // in mysterious ways, for unknown reasons.
180 virtual void do_void();
181 };
182
183
184 // YieldClosure is intended for use by iteration loops
185 // to incrementalize their work, allowing interleaving
186 // of an interruptable task so as to allow other
187 // threads to run (which may not otherwise be able to access
188 // exclusive resources, for instance). Additionally, the
189 // closure also allows for aborting an ongoing iteration
190 // by means of checking the return value from the polling
191 // call.
192 class YieldClosure : public StackObj {
193 public:
194 virtual bool should_return() = 0;
195 };
196
197 // Abstract closure for serializing data (read or write).
198
199 class SerializeOopClosure : public OopClosure {
200 public:
201 // Return bool indicating whether closure implements read or write.
202 virtual bool reading() const = 0;
203
204 // Read/write the int pointed to by i.
205 virtual void do_int(int* i) = 0;
206
207 // Read/write the size_t pointed to by i.
208 virtual void do_size_t(size_t* i) = 0;
209
210 // Read/write the void pointer pointed to by p.
211 virtual void do_ptr(void** p) = 0;
212
213 // Read/write the HeapWord pointer pointed to be p.
214 virtual void do_ptr(HeapWord** p) = 0;
215
216 // Read/write the region specified.
217 virtual void do_region(u_char* start, size_t size) = 0;
218
219 // Check/write the tag. If reading, then compare the tag against
220 // the passed in value and fail is they don't match. This allows
221 // for verification that sections of the serialized data are of the
222 // correct length.
223 virtual void do_tag(int tag) = 0;
224 };