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comparison src/share/vm/memory/iterator.hpp @ 6725:da91efe96a93

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6964458: Reimplement class meta-data storage to use native memory Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland Contributed-by: jmasa <jon.masamitsu@oracle.com>, stefank <stefan.karlsson@oracle.com>, mgerdin <mikael.gerdin@oracle.com>, never <tom.rodriguez@oracle.com>
author coleenp
date Sat, 01 Sep 2012 13:25:18 -0400
parents 1d1603768966
children ec98e58952b2
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6724:36d1d483d5d6 6725:da91efe96a93
1 /* 1 /*
2 * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved. 2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 * 4 *
5 * This code is free software; you can redistribute it and/or modify it 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 6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. 7 * published by the Free Software Foundation.
34 34
35 class CodeBlob; 35 class CodeBlob;
36 class nmethod; 36 class nmethod;
37 class ReferenceProcessor; 37 class ReferenceProcessor;
38 class DataLayout; 38 class DataLayout;
39 class KlassClosure;
40 class ClassLoaderData;
39 41
40 // Closure provides abortability. 42 // Closure provides abortability.
41 43
42 class Closure : public StackObj { 44 class Closure : public StackObj {
43 protected: 45 protected:
49 // functions that the iteration should cease. 51 // functions that the iteration should cease.
50 bool abort() { return _abort; } 52 bool abort() { return _abort; }
51 void clear_abort() { _abort = false; } 53 void clear_abort() { _abort = false; }
52 }; 54 };
53 55
54 // OopClosure is used for iterating through roots (oop*) 56 // OopClosure is used for iterating through references to Java objects.
55 57
56 class OopClosure : public Closure { 58 class OopClosure : public Closure {
57 public: 59 public:
58 ReferenceProcessor* _ref_processor;
59 OopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
60 OopClosure() : _ref_processor(NULL) { }
61 virtual void do_oop(oop* o) = 0; 60 virtual void do_oop(oop* o) = 0;
62 virtual void do_oop_v(oop* o) { do_oop(o); } 61 virtual void do_oop_v(oop* o) { do_oop(o); }
63 virtual void do_oop(narrowOop* o) = 0; 62 virtual void do_oop(narrowOop* o) = 0;
64 virtual void do_oop_v(narrowOop* o) { do_oop(o); } 63 virtual void do_oop_v(narrowOop* o) { do_oop(o); }
65 64 };
66 // In support of post-processing of weak links of KlassKlass objects; 65
67 // see KlassKlass::oop_oop_iterate(). 66 // ExtendedOopClosure adds extra code to be run during oop iterations.
68 67 // This is needed by the GC and is extracted to a separate type to not
69 virtual const bool should_remember_klasses() const { 68 // pollute the OopClosure interface.
70 assert(!must_remember_klasses(), "Should have overriden this method."); 69 class ExtendedOopClosure : public OopClosure {
71 return false; 70 public:
72 } 71 ReferenceProcessor* _ref_processor;
73 72 ExtendedOopClosure(ReferenceProcessor* rp) : _ref_processor(rp) { }
74 virtual void remember_klass(Klass* k) { /* do nothing */ } 73 ExtendedOopClosure() : OopClosure(), _ref_processor(NULL) { }
75 74
76 // In support of post-processing of weak references in 75 // If the do_metadata functions return "true",
77 // ProfileData (MethodDataOop) objects; see, for example, 76 // we invoke the following when running oop_iterate():
78 // VirtualCallData::oop_iterate(). 77 //
79 virtual const bool should_remember_mdo() const { return false; } 78 // 1) do_klass on the header klass pointer.
80 virtual void remember_mdo(DataLayout* v) { /* do nothing */ } 79 // 2) do_klass on the klass pointer in the mirrors.
81 80 // 3) do_class_loader_data on the class loader data in class loaders.
82 // The methods below control how object iterations invoking this closure 81 //
83 // should be performed: 82 // The virtual (without suffix) and the non-virtual (with _nv suffix) need
84 83 // to be updated together, or else the devirtualization will break.
85 // If "true", invoke on header klass field. 84 //
86 bool do_header() { return true; } // Note that this is non-virtual. 85 // Providing default implementations of the _nv functions unfortunately
86 // removes the compile-time safeness, but reduces the clutter for the
87 // ExtendedOopClosures that don't need to walk the metadata. Currently,
88 // only CMS needs these.
89
90 virtual bool do_metadata() { return do_metadata_nv(); }
91 bool do_metadata_v() { return do_metadata(); }
92 bool do_metadata_nv() { return false; }
93
94 virtual void do_klass(Klass* k) { do_klass_nv(k); }
95 void do_klass_v(Klass* k) { do_klass(k); }
96 void do_klass_nv(Klass* k) { ShouldNotReachHere(); }
97
98 virtual void do_class_loader_data(ClassLoaderData* cld) { ShouldNotReachHere(); }
99
87 // Controls how prefetching is done for invocations of this closure. 100 // Controls how prefetching is done for invocations of this closure.
88 Prefetch::style prefetch_style() { // Note that this is non-virtual. 101 Prefetch::style prefetch_style() { // Note that this is non-virtual.
89 return Prefetch::do_none; 102 return Prefetch::do_none;
90 } 103 }
91 104
92 // True iff this closure may be safely applied more than once to an oop 105 // 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). 106 // location without an intervening "major reset" (like the end of a GC).
94 virtual bool idempotent() { return false; } 107 virtual bool idempotent() { return false; }
95 virtual bool apply_to_weak_ref_discovered_field() { return false; } 108 virtual bool apply_to_weak_ref_discovered_field() { return false; }
96 109 };
97 #ifdef ASSERT 110
98 static bool _must_remember_klasses; 111 // Wrapper closure only used to implement oop_iterate_no_header().
99 static bool must_remember_klasses(); 112 class NoHeaderExtendedOopClosure : public ExtendedOopClosure {
100 static void set_must_remember_klasses(bool v); 113 OopClosure* _wrapped_closure;
101 #endif 114 public:
115 NoHeaderExtendedOopClosure(OopClosure* cl) : _wrapped_closure(cl) {}
116 // Warning: this calls the virtual version do_oop in the the wrapped closure.
117 void do_oop_nv(oop* p) { _wrapped_closure->do_oop(p); }
118 void do_oop_nv(narrowOop* p) { _wrapped_closure->do_oop(p); }
119
120 void do_oop(oop* p) { assert(false, "Only the _nv versions should be used");
121 _wrapped_closure->do_oop(p); }
122 void do_oop(narrowOop* p) { assert(false, "Only the _nv versions should be used");
123 _wrapped_closure->do_oop(p);}
124 };
125
126 class KlassClosure : public Closure {
127 public:
128 virtual void do_klass(Klass* k) = 0;
102 }; 129 };
103 130
104 // ObjectClosure is used for iterating through an object space 131 // ObjectClosure is used for iterating through an object space
105 132
106 class ObjectClosure : public Closure { 133 class ObjectClosure : public Closure {
116 }; 143 };
117 144
118 // Applies an oop closure to all ref fields in objects iterated over in an 145 // Applies an oop closure to all ref fields in objects iterated over in an
119 // object iteration. 146 // object iteration.
120 class ObjectToOopClosure: public ObjectClosure { 147 class ObjectToOopClosure: public ObjectClosure {
121 OopClosure* _cl; 148 ExtendedOopClosure* _cl;
122 public: 149 public:
123 void do_object(oop obj); 150 void do_object(oop obj);
124 ObjectToOopClosure(OopClosure* cl) : _cl(cl) {} 151 ObjectToOopClosure(ExtendedOopClosure* cl) : _cl(cl) {}
125 }; 152 };
126 153
127 // A version of ObjectClosure with "memory" (see _previous_address below) 154 // A version of ObjectClosure with "memory" (see _previous_address below)
128 class UpwardsObjectClosure: public BoolObjectClosure { 155 class UpwardsObjectClosure: public BoolObjectClosure {
129 HeapWord* _previous_address; 156 HeapWord* _previous_address;
261 virtual bool should_return() = 0; 288 virtual bool should_return() = 0;
262 }; 289 };
263 290
264 // Abstract closure for serializing data (read or write). 291 // Abstract closure for serializing data (read or write).
265 292
266 class SerializeOopClosure : public OopClosure { 293 class SerializeClosure : public Closure {
267 public: 294 public:
268 // Return bool indicating whether closure implements read or write. 295 // Return bool indicating whether closure implements read or write.
269 virtual bool reading() const = 0; 296 virtual bool reading() const = 0;
270 297
271 // Read/write the int pointed to by i.
272 virtual void do_int(int* i) = 0;
273
274 // Read/write the size_t pointed to by i.
275 virtual void do_size_t(size_t* i) = 0;
276
277 // Read/write the void pointer pointed to by p. 298 // Read/write the void pointer pointed to by p.
278 virtual void do_ptr(void** p) = 0; 299 virtual void do_ptr(void** p) = 0;
279
280 // Read/write the HeapWord pointer pointed to be p.
281 virtual void do_ptr(HeapWord** p) = 0;
282 300
283 // Read/write the region specified. 301 // Read/write the region specified.
284 virtual void do_region(u_char* start, size_t size) = 0; 302 virtual void do_region(u_char* start, size_t size) = 0;
285 303
286 // Check/write the tag. If reading, then compare the tag against 304 // Check/write the tag. If reading, then compare the tag against
304 static void store_symbol(Symbol** p, Symbol* sym) { 322 static void store_symbol(Symbol** p, Symbol* sym) {
305 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1)); 323 *p = (Symbol*)(intptr_t(sym) | (intptr_t(*p) & 1));
306 } 324 }
307 }; 325 };
308 326
309 #ifdef ASSERT
310 // This class is used to flag phases of a collection that
311 // can unload classes and which should override the
312 // should_remember_klasses() and remember_klass() of OopClosure.
313 // The _must_remember_klasses is set in the contructor and restored
314 // in the destructor. _must_remember_klasses is checked in assertions
315 // in the OopClosure implementations of should_remember_klasses() and
316 // remember_klass() and the expectation is that the OopClosure
317 // implementation should not be in use if _must_remember_klasses is set.
318 // Instances of RememberKlassesChecker can be place in
319 // marking phases of collections which can do class unloading.
320 // RememberKlassesChecker can be passed "false" to turn off checking.
321 // It is used by CMS when CMS yields to a different collector.
322 class RememberKlassesChecker: StackObj {
323 bool _saved_state;
324 bool _do_check;
325 public:
326 RememberKlassesChecker(bool checking_on) : _saved_state(false),
327 _do_check(true) {
328 // The ClassUnloading unloading flag affects the collectors except
329 // for CMS.
330 // CMS unloads classes if CMSClassUnloadingEnabled is true or
331 // if ExplicitGCInvokesConcurrentAndUnloadsClasses is true and
332 // the current collection is an explicit collection. Turning
333 // on the checking in general for
334 // ExplicitGCInvokesConcurrentAndUnloadsClasses and
335 // UseConcMarkSweepGC should not lead to false positives.
336 _do_check =
337 ClassUnloading && !UseConcMarkSweepGC ||
338 CMSClassUnloadingEnabled && UseConcMarkSweepGC ||
339 ExplicitGCInvokesConcurrentAndUnloadsClasses && UseConcMarkSweepGC;
340 if (_do_check) {
341 _saved_state = OopClosure::must_remember_klasses();
342 OopClosure::set_must_remember_klasses(checking_on);
343 }
344 }
345 ~RememberKlassesChecker() {
346 if (_do_check) {
347 OopClosure::set_must_remember_klasses(_saved_state);
348 }
349 }
350 };
351 #endif // ASSERT
352
353 #endif // SHARE_VM_MEMORY_ITERATOR_HPP 327 #endif // SHARE_VM_MEMORY_ITERATOR_HPP