1 /*
2 * Copyright (c) 1997, 2010, 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_CLASSFILE_SYMBOLTABLE_HPP
26 #define SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP
27
28 #include "memory/allocation.inline.hpp"
29 #include "oops/symbolOop.hpp"
30 #include "utilities/hashtable.hpp"
31
32 // The symbol table holds all symbolOops and corresponding interned strings.
33 // symbolOops and literal strings should be canonicalized.
34 //
35 // The interned strings are created lazily.
36 //
37 // It is implemented as an open hash table with a fixed number of buckets.
38 //
39 // %note:
40 // - symbolTableEntrys are allocated in blocks to reduce the space overhead.
41
42 class BoolObjectClosure;
43
44
45 class SymbolTable : public Hashtable {
46 friend class VMStructs;
47
48 private:
49 // The symbol table
50 static SymbolTable* _the_table;
51
52 // Adding elements
53 symbolOop basic_add(int index, u1* name, int len,
54 unsigned int hashValue, TRAPS);
55 bool basic_add(constantPoolHandle cp, int names_count,
56 const char** names, int* lengths, int* cp_indices,
57 unsigned int* hashValues, TRAPS);
58
59 // Table size
60 enum {
61 symbol_table_size = 20011
62 };
63
64 symbolOop lookup(int index, const char* name, int len, unsigned int hash);
65
66 SymbolTable()
67 : Hashtable(symbol_table_size, sizeof (HashtableEntry)) {}
68
69 SymbolTable(HashtableBucket* t, int number_of_entries)
70 : Hashtable(symbol_table_size, sizeof (HashtableEntry), t,
71 number_of_entries) {}
72
73
74 public:
75 enum {
76 symbol_alloc_batch_size = 8
77 };
78
79 // The symbol table
80 static SymbolTable* the_table() { return _the_table; }
81
82 static void create_table() {
83 assert(_the_table == NULL, "One symbol table allowed.");
84 _the_table = new SymbolTable();
85 }
86
87 static void create_table(HashtableBucket* t, int length,
88 int number_of_entries) {
89 assert(_the_table == NULL, "One symbol table allowed.");
90 assert(length == symbol_table_size * sizeof(HashtableBucket),
91 "bad shared symbol size.");
92 _the_table = new SymbolTable(t, number_of_entries);
93 }
94
95 static symbolOop lookup(const char* name, int len, TRAPS);
96 // lookup only, won't add. Also calculate hash.
97 static symbolOop lookup_only(const char* name, int len, unsigned int& hash);
98 // Only copy to C string to be added if lookup failed.
99 static symbolOop lookup(symbolHandle sym, int begin, int end, TRAPS);
100
101 // jchar (utf16) version of lookups
102 static symbolOop lookup_unicode(const jchar* name, int len, TRAPS);
103 static symbolOop lookup_only_unicode(const jchar* name, int len, unsigned int& hash);
104
105 static void add(constantPoolHandle cp, int names_count,
106 const char** names, int* lengths, int* cp_indices,
107 unsigned int* hashValues, TRAPS);
108
109 // GC support
110 // Delete pointers to otherwise-unreachable objects.
111 static void unlink(BoolObjectClosure* cl) {
112 the_table()->Hashtable::unlink(cl);
113 }
114
115 // Invoke "f->do_oop" on the locations of all oops in the table.
116 static void oops_do(OopClosure* f) {
117 the_table()->Hashtable::oops_do(f);
118 }
119
120 // Symbol lookup
121 static symbolOop lookup(int index, const char* name, int len, TRAPS);
122
123 // Needed for preloading classes in signatures when compiling.
124 // Returns the symbol is already present in symbol table, otherwise
125 // NULL. NO ALLOCATION IS GUARANTEED!
126 static symbolOop probe(const char* name, int len) {
127 unsigned int ignore_hash;
128 return lookup_only(name, len, ignore_hash);
129 }
130 static symbolOop probe_unicode(const jchar* name, int len) {
131 unsigned int ignore_hash;
132 return lookup_only_unicode(name, len, ignore_hash);
133 }
134
135 // Histogram
136 static void print_histogram() PRODUCT_RETURN;
137
138 // Debugging
139 static void verify();
140
141 // Sharing
142 static void copy_buckets(char** top, char*end) {
143 the_table()->Hashtable::copy_buckets(top, end);
144 }
145 static void copy_table(char** top, char*end) {
146 the_table()->Hashtable::copy_table(top, end);
147 }
148 static void reverse(void* boundary = NULL) {
149 ((Hashtable*)the_table())->reverse(boundary);
150 }
151 };
152
153
154 class StringTable : public Hashtable {
155 friend class VMStructs;
156
157 private:
158 // The string table
159 static StringTable* _the_table;
160
161 static oop intern(Handle string_or_null, jchar* chars, int length, TRAPS);
162 oop basic_add(int index, Handle string_or_null, jchar* name, int len,
163 unsigned int hashValue, TRAPS);
164
165 // Table size
166 enum {
167 string_table_size = 1009
168 };
169
170 oop lookup(int index, jchar* chars, int length, unsigned int hashValue);
171
172 StringTable() : Hashtable(string_table_size, sizeof (HashtableEntry)) {}
173
174 StringTable(HashtableBucket* t, int number_of_entries)
175 : Hashtable(string_table_size, sizeof (HashtableEntry), t,
176 number_of_entries) {}
177
178 public:
179 // The string table
180 static StringTable* the_table() { return _the_table; }
181
182 static void create_table() {
183 assert(_the_table == NULL, "One string table allowed.");
184 _the_table = new StringTable();
185 }
186
187 static void create_table(HashtableBucket* t, int length,
188 int number_of_entries) {
189 assert(_the_table == NULL, "One string table allowed.");
190 assert(length == string_table_size * sizeof(HashtableBucket),
191 "bad shared string size.");
192 _the_table = new StringTable(t, number_of_entries);
193 }
194
195
196 static int hash_string(jchar* s, int len);
197
198
199 // GC support
200 // Delete pointers to otherwise-unreachable objects.
201 static void unlink(BoolObjectClosure* cl) {
202 the_table()->Hashtable::unlink(cl);
203 }
204
205 // Invoke "f->do_oop" on the locations of all oops in the table.
206 static void oops_do(OopClosure* f) {
207 the_table()->Hashtable::oops_do(f);
208 }
209
210 // Probing
211 static oop lookup(symbolOop symbol);
212
213 // Interning
214 static oop intern(symbolOop symbol, TRAPS);
215 static oop intern(oop string, TRAPS);
216 static oop intern(const char *utf8_string, TRAPS);
217
218 // Debugging
219 static void verify();
220
221 // Sharing
222 static void copy_buckets(char** top, char*end) {
223 the_table()->Hashtable::copy_buckets(top, end);
224 }
225 static void copy_table(char** top, char*end) {
226 the_table()->Hashtable::copy_table(top, end);
227 }
228 static void reverse() {
229 ((BasicHashtable*)the_table())->reverse();
230 }
231 };
232
233 #endif // SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP