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src/hotspot/share/prims/jvmtiTagMapTable.hpp

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  1 /*
  2  * Copyright (c) 2020, 2023, 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_VM_PRIMS_TAGMAPTABLE_HPP
 26 #define SHARE_VM_PRIMS_TAGMAPTABLE_HPP
 27 
 28 #include "gc/shared/collectedHeap.hpp"
 29 #include "memory/allocation.hpp"

 30 #include "oops/weakHandle.hpp"
 31 #include "utilities/resizeableResourceHash.hpp"
 32 
 33 class JvmtiEnv;
 34 class JvmtiTagMapKeyClosure;









































 35 
 36 // The oop is needed for lookup rather than creating a WeakHandle during
 37 // lookup because the HeapWalker may walk soon to be dead objects and
 38 // creating a WeakHandle for an otherwise dead object makes G1 unhappy.
 39 //
 40 // This class is the Key type for inserting in ResizeableResourceHashTable
 41 // Its get_hash() and equals() methods are also used for getting the hash
 42 // value of a Key and comparing two Keys, respectively.








 43 class JvmtiTagMapKey : public CHeapObj<mtServiceability> {
 44   WeakHandle _wh;
 45   oop _obj; // temporarily hold obj while searching






 46  public:
 47   JvmtiTagMapKey(oop obj);

 48   JvmtiTagMapKey(const JvmtiTagMapKey& src);

 49   JvmtiTagMapKey& operator=(const JvmtiTagMapKey&) = delete;
 50 


 51   oop object() const;
 52   oop object_no_keepalive() const;
 53   void release_weak_handle();
 54 
 55   static unsigned get_hash(const JvmtiTagMapKey& entry) {
 56     assert(entry._obj != nullptr, "must lookup obj to hash");
 57     return (unsigned)entry._obj->identity_hash();
 58   }
 59 
 60   static bool equals(const JvmtiTagMapKey& lhs, const JvmtiTagMapKey& rhs) {
 61     oop lhs_obj = lhs._obj != nullptr ? lhs._obj : lhs.object_no_keepalive();
 62     oop rhs_obj = rhs._obj != nullptr ? rhs._obj : rhs.object_no_keepalive();
 63     return lhs_obj == rhs_obj;
 64   }
 65 };
 66 
 67 typedef
 68 ResizeableResourceHashtable <JvmtiTagMapKey, jlong,
 69                               AnyObj::C_HEAP, mtServiceability,
 70                               JvmtiTagMapKey::get_hash,
 71                               JvmtiTagMapKey::equals> ResizableResourceHT;






 72 
 73 class JvmtiTagMapTable : public CHeapObj<mtServiceability> {
 74  private:
 75   ResizableResourceHT _table;
 76 


 77  public:
 78   JvmtiTagMapTable();
 79   ~JvmtiTagMapTable();
 80 
 81   jlong find(oop obj);
 82   void add(oop obj, jlong tag);





 83 
 84   void remove(oop obj);
 85 
 86   // iterate over all entries in the hashmap
 87   void entry_iterate(JvmtiTagMapKeyClosure* closure);
 88 
 89   bool is_empty() const { return _table.number_of_entries() == 0; }
 90 
 91   // Cleanup cleared entries and store dead object tags in objects array
 92   void remove_dead_entries(GrowableArray<jlong>* objects);
 93   void clear();
 94 };
 95 
 96 // A supporting class for iterating over all entries in Hashmap
 97 class JvmtiTagMapKeyClosure {
 98  public:
 99   virtual bool do_entry(JvmtiTagMapKey& key, jlong& value) = 0;
































































100 };
101 
102 #endif // SHARE_VM_PRIMS_TAGMAPTABLE_HPP

  1 /*
  2  * Copyright (c) 2020, 2024, 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_VM_PRIMS_TAGMAPTABLE_HPP
 26 #define SHARE_VM_PRIMS_TAGMAPTABLE_HPP
 27 
 28 #include "gc/shared/collectedHeap.hpp"
 29 #include "memory/allocation.hpp"
 30 #include "oops/layoutKind.hpp"
 31 #include "oops/weakHandle.hpp"
 32 #include "utilities/resizeableResourceHash.hpp"
 33 
 34 class JvmtiEnv;
 35 
 36 // Describes an object which can be tagged during heap walk operation.
 37 // - generic heap object: _obj: oop, offset == 0, _inline_klass == nullptr;
 38 // - value heap object: _obj: oop, offset == 0, _inline_klass == _obj.klass();
 39 // - flat value object: _obj: holder object, offset == offset in the holder, _inline_klass == klass of the flattened object;
 40 class JvmtiHeapwalkObject {
 41   oop _obj;                   // for flattened value object this is holder object
 42   int _offset;                // == 0 for heap objects
 43   InlineKlass* _inline_klass; // for value object, nullptr otherwise
 44   LayoutKind _layout_kind;    // layout kind in holder object, used only for flat->heap conversion
 45 
 46   static InlineKlass* inline_klass_or_null(oop obj) {
 47     Klass* k = obj->klass();
 48     return k->is_inline_klass() ? InlineKlass::cast(k) : nullptr;
 49   }
 50 public:
 51   JvmtiHeapwalkObject(): _obj(nullptr), _offset(0), _inline_klass(nullptr), _layout_kind(LayoutKind::UNKNOWN) {}
 52   JvmtiHeapwalkObject(oop obj): _obj(obj), _offset(0), _inline_klass(inline_klass_or_null(obj)), _layout_kind(LayoutKind::REFERENCE) {}
 53   JvmtiHeapwalkObject(oop obj, int offset, InlineKlass* ik, LayoutKind lk): _obj(obj), _offset(offset), _inline_klass(ik), _layout_kind(lk) {}
 54 
 55   inline bool is_empty() const { return _obj == nullptr; }
 56   inline bool is_value() const { return _inline_klass != nullptr; }
 57   inline bool is_flat() const { return _offset != 0; }
 58 
 59   inline oop obj() const { return _obj; }
 60   inline int offset() const { return _offset; }
 61   inline InlineKlass* inline_klass() const { return _inline_klass; }
 62   inline LayoutKind layout_kind() const { return _layout_kind; }
 63 
 64   inline Klass* klass() const { return is_value() ? _inline_klass : obj()->klass(); }
 65 
 66   static bool equals(const JvmtiHeapwalkObject& obj1, const JvmtiHeapwalkObject& obj2);
 67 
 68   bool operator==(const JvmtiHeapwalkObject& other) const {
 69     // need to compare inline_klass too to handle the case when flat object has flat field at offset 0
 70     return _obj == other._obj && _offset == other._offset && _inline_klass == other._inline_klass;
 71   }
 72   bool operator!=(const JvmtiHeapwalkObject& other) const {
 73     return !(*this == other);
 74   }
 75 };
 76 
 77 
 78 // The oop is needed for lookup rather than creating a WeakHandle during
 79 // lookup because the HeapWalker may walk soon to be dead objects and
 80 // creating a WeakHandle for an otherwise dead object makes G1 unhappy.
 81 //
 82 // This class is the Key type for inserting in ResizeableResourceHashTable
 83 // Its get_hash() and equals() methods are also used for getting the hash
 84 // value of a Key and comparing two Keys, respectively.
 85 //
 86 // Value objects: keep just one tag for all equal value objects including heap allocated value objects.
 87 // We have to keep a strong reference to each unique value object with a non-zero tag.
 88 // During heap walking flattened value object tags stored in separate JvmtiFlatTagMapTable,
 89 // converted to standard strong entries in JvmtiTagMapTable outside of sefepoint.
 90 // All equal value objects should have the same tag.
 91 // Keep value objects alive (1 copy for each "value") until their tags are removed.
 92 
 93 class JvmtiTagMapKey : public CHeapObj<mtServiceability> {
 94   union {
 95     WeakHandle _wh;
 96     OopHandle _h; // for value objects (_is_weak == false)
 97   };
 98   bool _is_weak;
 99   // temporarily hold obj while searching
100   const JvmtiHeapwalkObject* _obj;
101 
102  public:
103   JvmtiTagMapKey(const JvmtiHeapwalkObject* obj);
104   // Copy ctor is called when we put entry to the hash table.
105   JvmtiTagMapKey(const JvmtiTagMapKey& src);
106 
107   JvmtiTagMapKey& operator=(const JvmtiTagMapKey&) = delete;
108 
109   JvmtiHeapwalkObject heapwalk_object() const;
110 
111   oop object() const;
112   oop object_no_keepalive() const;
113   void release_handle();





114 
115   static unsigned get_hash(const JvmtiTagMapKey& entry);
116   static bool equals(const JvmtiTagMapKey& lhs, const JvmtiTagMapKey& rhs);



117 };
118 
119 typedef
120 ResizeableResourceHashtable <JvmtiTagMapKey, jlong,
121                              AnyObj::C_HEAP, mtServiceability,
122                              JvmtiTagMapKey::get_hash,
123                              JvmtiTagMapKey::equals> ResizableResourceHT;
124 
125 // A supporting class for iterating over all entries in Hashmap
126 class JvmtiTagMapKeyClosure {
127 public:
128   virtual bool do_entry(JvmtiTagMapKey& key, jlong& value) = 0;
129 };
130 
131 class JvmtiTagMapTable : public CHeapObj<mtServiceability> {
132  private:
133   ResizableResourceHT _table;
134 
135   jlong* lookup(const JvmtiHeapwalkObject& obj) const;
136 
137  public:
138   JvmtiTagMapTable();
139   ~JvmtiTagMapTable();
140 
141   int number_of_entries() const { return _table.number_of_entries(); }
142 
143   jlong find(const JvmtiHeapwalkObject& obj) const;
144   // obj cannot be flat
145   void add(const JvmtiHeapwalkObject& obj, jlong tag);
146   // update the tag if the entry exists, returns false otherwise
147   bool update(const JvmtiHeapwalkObject& obj, jlong tag);
148 
149   bool remove(const JvmtiHeapwalkObject& obj);
150 
151   // iterate over all entries in the hashmap
152   void entry_iterate(JvmtiTagMapKeyClosure* closure);
153 
154   bool is_empty() const { return _table.number_of_entries() == 0; }
155 
156   // Cleanup cleared entries and store dead object tags in objects array
157   void remove_dead_entries(GrowableArray<jlong>* objects);
158   void clear();
159 };
160 
161 
162 // This class is the Key type for hash table to keep flattened value objects during heap walk operations.
163 // The objects needs to be moved to JvmtiTagMapTable outside of safepoint.
164 class JvmtiFlatTagMapKey: public CHeapObj<mtServiceability> {
165 private:
166   // holder object
167   OopHandle _h;
168   // temporarily holds holder object while searching
169   oop _holder;
170   int _offset;
171   InlineKlass* _inline_klass;
172   LayoutKind _layout_kind;
173 public:
174   JvmtiFlatTagMapKey(const JvmtiHeapwalkObject& obj);
175   // Copy ctor is called when we put entry to the hash table.
176   JvmtiFlatTagMapKey(const JvmtiFlatTagMapKey& src);
177 
178   JvmtiFlatTagMapKey& operator=(const JvmtiFlatTagMapKey&) = delete;
179 
180   JvmtiHeapwalkObject heapwalk_object() const;
181 
182   oop holder() const;
183   oop holder_no_keepalive() const;
184   int offset() const { return _offset; }
185   InlineKlass* inline_klass() const { return _inline_klass; }
186   LayoutKind layout_kind() const { return _layout_kind; }
187 
188   void release_handle();
189 
190   static unsigned get_hash(const JvmtiFlatTagMapKey& entry);
191   static bool equals(const JvmtiFlatTagMapKey& lhs, const JvmtiFlatTagMapKey& rhs);
192 };
193 
194 typedef
195 ResizeableResourceHashtable <JvmtiFlatTagMapKey, jlong,
196                              AnyObj::C_HEAP, mtServiceability,
197                              JvmtiFlatTagMapKey::get_hash,
198                              JvmtiFlatTagMapKey::equals> FlatObjectHashtable;
199 
200 // A supporting class for iterating over all entries in JvmtiFlatTagMapTable.
201 class JvmtiFlatTagMapKeyClosure {
202 public:
203   virtual bool do_entry(JvmtiFlatTagMapKey& key, jlong& value) = 0;
204 };
205 
206 class JvmtiFlatTagMapTable: public CHeapObj<mtServiceability> {
207 private:
208   FlatObjectHashtable _table;
209 
210 public:
211   JvmtiFlatTagMapTable();
212   ~JvmtiFlatTagMapTable();
213 
214   int number_of_entries() const { return _table.number_of_entries(); }
215 
216   jlong find(const JvmtiHeapwalkObject& obj) const;
217   // obj must be flat
218   void add(const JvmtiHeapwalkObject& obj, jlong tag);
219 
220   // returns tag for the entry, 0 is not found
221   jlong remove(const JvmtiHeapwalkObject& obj);
222 
223   // iterate over entries in the hashmap
224   void entry_iterate(JvmtiFlatTagMapKeyClosure* closure);
225 
226   bool is_empty() const { return _table.number_of_entries() == 0; }
227 
228   void clear();
229 };
230 
231 #endif // SHARE_VM_PRIMS_TAGMAPTABLE_HPP
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