Wed, 01 May 2013 08:07:59 -0700
8013418: assert(i == total_args_passed) in AdapterHandlerLibrary::get_adapter since 8-b87
Summary: Do not treat static methods as miranda methods.
Reviewed-by: dholmes, acorn
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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.
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23 */
25 #ifndef SHARE_VM_OOPS_SYMBOL_HPP
26 #define SHARE_VM_OOPS_SYMBOL_HPP
28 #include "utilities/utf8.hpp"
29 #include "memory/allocation.hpp"
31 // A Symbol is a canonicalized string.
32 // All Symbols reside in global SymbolTable and are reference counted.
34 // Reference counting
35 //
36 // All Symbols are allocated and added to the SymbolTable.
37 // When a class is unloaded, the reference counts of the Symbol pointers in
38 // the ConstantPool and in InstanceKlass (see release_C_heap_structures) are
39 // decremented. When the reference count for a Symbol goes to 0, the garbage
40 // collector can free the Symbol and remove it from the SymbolTable.
41 //
42 // 0) Symbols need to be reference counted when a pointer to the Symbol is
43 // saved in persistent storage. This does not include the pointer
44 // in the SymbolTable bucket (the _literal field in HashtableEntry)
45 // that points to the Symbol. All other stores of a Symbol*
46 // to a field of a persistent variable (e.g., the _name filed in
47 // FieldAccessInfo or _ptr in a CPSlot) is reference counted.
48 //
49 // 1) The lookup of a "name" in the SymbolTable either creates a Symbol F for
50 // "name" and returns a pointer to F or finds a pre-existing Symbol F for
51 // "name" and returns a pointer to it. In both cases the reference count for F
52 // is incremented under the assumption that a pointer to F will be created from
53 // the return value. Thus the increment of the reference count is on the lookup
54 // and not on the assignment to the new Symbol*. That is
55 // Symbol* G = lookup()
56 // ^ increment on lookup()
57 // and not
58 // Symbol* G = lookup()
59 // ^ increment on assignmnet
60 // The reference count must be decremented manually when the copy of the
61 // pointer G is destroyed.
62 //
63 // 2) For a local Symbol* A that is a copy of an existing Symbol* B, the
64 // reference counting is elided when the scope of B is greater than the scope
65 // of A. For example, in the code fragment
66 // below "klass" is passed as a parameter to the method. Symbol* "kn"
67 // is a copy of the name in "klass".
68 //
69 // Symbol* kn = klass->name();
70 // unsigned int d_hash = dictionary()->compute_hash(kn, class_loader);
71 //
72 // The scope of "klass" is greater than the scope of "kn" so the reference
73 // counting for "kn" is elided.
74 //
75 // Symbol* copied from ConstantPool entries are good candidates for reference
76 // counting elision. The ConstantPool entries for a class C exist until C is
77 // unloaded. If a Symbol* is copied out of the ConstantPool into Symbol* X,
78 // the Symbol* in the ConstantPool will in general out live X so the reference
79 // counting on X can be elided.
80 //
81 // For cases where the scope of A is not greater than the scope of B,
82 // the reference counting is explicitly done. See ciSymbol,
83 // ResolutionErrorEntry and ClassVerifier for examples.
84 //
85 // 3) When a Symbol K is created for temporary use, generally for substrings of
86 // an existing symbol or to create a new symbol, assign it to a
87 // TempNewSymbol. The SymbolTable methods new_symbol(), lookup()
88 // and probe() all potentially return a pointer to a new Symbol.
89 // The allocation (or lookup) of K increments the reference count for K
90 // and the destructor decrements the reference count.
91 //
92 // Another example of TempNewSymbol usage is parsed_name used in
93 // ClassFileParser::parseClassFile() where parsed_name is used in the cleanup
94 // after a failed attempt to load a class. Here parsed_name is a
95 // TempNewSymbol (passed in as a parameter) so the reference count on its symbol
96 // will be decremented when it goes out of scope.
99 // This cannot be inherited from ResourceObj because it cannot have a vtable.
100 // Since sometimes this is allocated from Metadata, pick a base allocation
101 // type without virtual functions.
102 class ClassLoaderData;
104 class Symbol : public MetaspaceObj {
105 friend class VMStructs;
106 friend class SymbolTable;
107 friend class MoveSymbols;
108 private:
109 volatile int _refcount;
110 int _identity_hash;
111 unsigned short _length; // number of UTF8 characters in the symbol
112 jbyte _body[1];
114 enum {
115 // max_symbol_length is constrained by type of _length
116 max_symbol_length = (1 << 16) -1
117 };
119 static int size(int length) {
120 size_t sz = heap_word_size(sizeof(Symbol) + (length > 0 ? length - 1 : 0));
121 return align_object_size(sz);
122 }
124 void byte_at_put(int index, int value) {
125 assert(index >=0 && index < _length, "symbol index overflow");
126 _body[index] = value;
127 }
129 Symbol(const u1* name, int length, int refcount);
130 void* operator new(size_t size, int len, TRAPS);
131 void* operator new(size_t size, int len, Arena* arena, TRAPS);
132 void* operator new(size_t size, int len, ClassLoaderData* loader_data, TRAPS);
134 void operator delete(void* p);
136 public:
137 // Low-level access (used with care, since not GC-safe)
138 const jbyte* base() const { return &_body[0]; }
140 int size() { return size(utf8_length()); }
142 // Returns the largest size symbol we can safely hold.
143 static int max_length() { return max_symbol_length; }
145 int identity_hash() { return _identity_hash; }
147 // For symbol table alternate hashing
148 unsigned int new_hash(jint seed);
150 // Reference counting. See comments above this class for when to use.
151 int refcount() const { return _refcount; }
152 void increment_refcount();
153 void decrement_refcount();
155 int byte_at(int index) const {
156 assert(index >=0 && index < _length, "symbol index overflow");
157 return base()[index];
158 }
160 const jbyte* bytes() const { return base(); }
162 int utf8_length() const { return _length; }
164 // Compares the symbol with a string.
165 bool equals(const char* str, int len) const;
166 bool equals(const char* str) const { return equals(str, (int) strlen(str)); }
168 // Tests if the symbol starts with the given prefix.
169 bool starts_with(const char* prefix, int len) const;
170 bool starts_with(const char* prefix) const {
171 return starts_with(prefix, (int) strlen(prefix));
172 }
174 // Tests if the symbol starts with the given prefix.
175 int index_of_at(int i, const char* str, int len) const;
176 int index_of_at(int i, const char* str) const {
177 return index_of_at(i, str, (int) strlen(str));
178 }
180 // Three-way compare for sorting; returns -1/0/1 if receiver is </==/> than arg
181 // note that the ordering is not alfabetical
182 inline int fast_compare(Symbol* other) const;
184 // Returns receiver converted to null-terminated UTF-8 string; string is
185 // allocated in resource area, or in the char buffer provided by caller.
186 char* as_C_string() const;
187 char* as_C_string(char* buf, int size) const;
188 // Use buf if needed buffer length is <= size.
189 char* as_C_string_flexible_buffer(Thread* t, char* buf, int size) const;
191 // Returns an escaped form of a Java string.
192 char* as_quoted_ascii() const;
194 // Returns a null terminated utf8 string in a resource array
195 char* as_utf8() const { return as_C_string(); }
196 char* as_utf8_flexible_buffer(Thread* t, char* buf, int size) const {
197 return as_C_string_flexible_buffer(t, buf, size);
198 }
200 jchar* as_unicode(int& length) const;
202 // Treating this symbol as a class name, returns the Java name for the class.
203 // String is allocated in resource area if buffer is not provided.
204 // See Klass::external_name()
205 const char* as_klass_external_name() const;
206 const char* as_klass_external_name(char* buf, int size) const;
208 // Printing
209 void print_symbol_on(outputStream* st = NULL) const;
210 void print_on(outputStream* st) const; // First level print
211 void print_value_on(outputStream* st) const; // Second level print.
213 // printing on default output stream
214 void print() { print_on(tty); }
215 void print_value() { print_value_on(tty); }
217 #ifndef PRODUCT
218 // Empty constructor to create a dummy symbol object on stack
219 // only for getting its vtable pointer.
220 Symbol() { }
222 static int _total_count;
223 #endif
224 };
226 // Note: this comparison is used for vtable sorting only; it doesn't matter
227 // what order it defines, as long as it is a total, time-invariant order
228 // Since Symbol*s are in C_HEAP, their relative order in memory never changes,
229 // so use address comparison for speed
230 int Symbol::fast_compare(Symbol* other) const {
231 return (((uintptr_t)this < (uintptr_t)other) ? -1
232 : ((uintptr_t)this == (uintptr_t) other) ? 0 : 1);
233 }
234 #endif // SHARE_VM_OOPS_SYMBOL_HPP