1 /*
2 * Copyright (c) 1997, 2009, 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 // The symbol table holds all symbolOops and corresponding interned strings.
26 // symbolOops and literal strings should be canonicalized.
27 //
28 // The interned strings are created lazily.
29 //
30 // It is implemented as an open hash table with a fixed number of buckets.
31 //
32 // %note:
33 // - symbolTableEntrys are allocated in blocks to reduce the space overhead.
34
35 class BoolObjectClosure;
36
37
38 class SymbolTable : public Hashtable {
39 friend class VMStructs;
40
41 private:
42 // The symbol table
43 static SymbolTable* _the_table;
44
45 // Adding elements
46 symbolOop basic_add(int index, u1* name, int len,
47 unsigned int hashValue, TRAPS);
48 bool basic_add(constantPoolHandle cp, int names_count,
49 const char** names, int* lengths, int* cp_indices,
50 unsigned int* hashValues, TRAPS);
51
52 // Table size
53 enum {
54 symbol_table_size = 20011
55 };
56
57 symbolOop lookup(int index, const char* name, int len, unsigned int hash);
58
59 SymbolTable()
60 : Hashtable(symbol_table_size, sizeof (HashtableEntry)) {}
61
62 SymbolTable(HashtableBucket* t, int number_of_entries)
63 : Hashtable(symbol_table_size, sizeof (HashtableEntry), t,
64 number_of_entries) {}
65
66
67 public:
68 enum {
69 symbol_alloc_batch_size = 8
70 };
71
72 // The symbol table
73 static SymbolTable* the_table() { return _the_table; }
74
75 static void create_table() {
76 assert(_the_table == NULL, "One symbol table allowed.");
77 _the_table = new SymbolTable();
78 }
79
80 static void create_table(HashtableBucket* t, int length,
81 int number_of_entries) {
82 assert(_the_table == NULL, "One symbol table allowed.");
83 assert(length == symbol_table_size * sizeof(HashtableBucket),
84 "bad shared symbol size.");
85 _the_table = new SymbolTable(t, number_of_entries);
86 }
87
88 static symbolOop lookup(const char* name, int len, TRAPS);
89 // lookup only, won't add. Also calculate hash.
90 static symbolOop lookup_only(const char* name, int len, unsigned int& hash);
91 // Only copy to C string to be added if lookup failed.
92 static symbolOop lookup(symbolHandle sym, int begin, int end, TRAPS);
93
94 // jchar (utf16) version of lookups
95 static symbolOop lookup_unicode(const jchar* name, int len, TRAPS);
96 static symbolOop lookup_only_unicode(const jchar* name, int len, unsigned int& hash);
97
98 static void add(constantPoolHandle cp, int names_count,
99 const char** names, int* lengths, int* cp_indices,
100 unsigned int* hashValues, TRAPS);
101
102 // GC support
103 // Delete pointers to otherwise-unreachable objects.
104 static void unlink(BoolObjectClosure* cl) {
105 the_table()->Hashtable::unlink(cl);
106 }
107
108 // Invoke "f->do_oop" on the locations of all oops in the table.
109 static void oops_do(OopClosure* f) {
110 the_table()->Hashtable::oops_do(f);
111 }
112
113 // Symbol lookup
114 static symbolOop lookup(int index, const char* name, int len, TRAPS);
115
116 // Needed for preloading classes in signatures when compiling.
117 // Returns the symbol is already present in symbol table, otherwise
118 // NULL. NO ALLOCATION IS GUARANTEED!
119 static symbolOop probe(const char* name, int len) {
120 unsigned int ignore_hash;
121 return lookup_only(name, len, ignore_hash);
122 }
123 static symbolOop probe_unicode(const jchar* name, int len) {
124 unsigned int ignore_hash;
125 return lookup_only_unicode(name, len, ignore_hash);
126 }
127
128 // Histogram
129 static void print_histogram() PRODUCT_RETURN;
130
131 // Debugging
132 static void verify();
133
134 // Sharing
135 static void copy_buckets(char** top, char*end) {
136 the_table()->Hashtable::copy_buckets(top, end);
137 }
138 static void copy_table(char** top, char*end) {
139 the_table()->Hashtable::copy_table(top, end);
140 }
141 static void reverse(void* boundary = NULL) {
142 ((Hashtable*)the_table())->reverse(boundary);
143 }
144 };
145
146
147 class StringTable : public Hashtable {
148 friend class VMStructs;
149
150 private:
151 // The string table
152 static StringTable* _the_table;
153
154 static oop intern(Handle string_or_null, jchar* chars, int length, TRAPS);
155 oop basic_add(int index, Handle string_or_null, jchar* name, int len,
156 unsigned int hashValue, TRAPS);
157
158 // Table size
159 enum {
160 string_table_size = 1009
161 };
162
163 oop lookup(int index, jchar* chars, int length, unsigned int hashValue);
164
165 StringTable() : Hashtable(string_table_size, sizeof (HashtableEntry)) {}
166
167 StringTable(HashtableBucket* t, int number_of_entries)
168 : Hashtable(string_table_size, sizeof (HashtableEntry), t,
169 number_of_entries) {}
170
171 public:
172 // The string table
173 static StringTable* the_table() { return _the_table; }
174
175 static void create_table() {
176 assert(_the_table == NULL, "One string table allowed.");
177 _the_table = new StringTable();
178 }
179
180 static void create_table(HashtableBucket* t, int length,
181 int number_of_entries) {
182 assert(_the_table == NULL, "One string table allowed.");
183 assert(length == string_table_size * sizeof(HashtableBucket),
184 "bad shared string size.");
185 _the_table = new StringTable(t, number_of_entries);
186 }
187
188
189 static int hash_string(jchar* s, int len);
190
191
192 // GC support
193 // Delete pointers to otherwise-unreachable objects.
194 static void unlink(BoolObjectClosure* cl) {
195 the_table()->Hashtable::unlink(cl);
196 }
197
198 // Invoke "f->do_oop" on the locations of all oops in the table.
199 static void oops_do(OopClosure* f) {
200 the_table()->Hashtable::oops_do(f);
201 }
202
203 // Probing
204 static oop lookup(symbolOop symbol);
205
206 // Interning
207 static oop intern(symbolOop symbol, TRAPS);
208 static oop intern(oop string, TRAPS);
209 static oop intern(const char *utf8_string, TRAPS);
210
211 // Debugging
212 static void verify();
213
214 // Sharing
215 static void copy_buckets(char** top, char*end) {
216 the_table()->Hashtable::copy_buckets(top, end);
217 }
218 static void copy_table(char** top, char*end) {
219 the_table()->Hashtable::copy_table(top, end);
220 }
221 static void reverse() {
222 ((BasicHashtable*)the_table())->reverse();
223 }
224 };