1 /*
2 * Copyright (c) 1997, 2016, 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
26 #include "precompiled.hpp"
27 #include "classfile/altHashing.hpp"
28 #include "classfile/classLoaderData.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/symbol.hpp"
32 #include "runtime/atomic.hpp"
33 #include "runtime/os.hpp"
34
35 Symbol::Symbol(const u1* name, int length, int refcount) {
36 _refcount = refcount;
37 _length = length;
38 _identity_hash = (short)os::random();
39 for (int i = 0; i < _length; i++) {
40 byte_at_put(i, name[i]);
41 }
42 }
43
44 void* Symbol::operator new(size_t sz, int len, TRAPS) throw() {
45 int alloc_size = size(len)*wordSize;
46 address res = (address) AllocateHeap(alloc_size, mtSymbol);
47 return res;
48 }
49
50 void* Symbol::operator new(size_t sz, int len, Arena* arena, TRAPS) throw() {
51 int alloc_size = size(len)*wordSize;
52 address res = (address)arena->Amalloc_4(alloc_size);
53 return res;
54 }
55
56 void* Symbol::operator new(size_t sz, int len, ClassLoaderData* loader_data, TRAPS) throw() {
57 address res;
58 res = (address) Metaspace::allocate(loader_data, size(len), true,
59 MetaspaceObj::SymbolType, CHECK_NULL);
60 return res;
61 }
62
63 void Symbol::operator delete(void *p) {
64 assert(((Symbol*)p)->refcount() == 0, "should not call this");
65 FreeHeap(p);
66 }
67
68 // ------------------------------------------------------------------
69 // Symbol::equals
70 //
71 // Compares the symbol with a string of the given length.
72 bool Symbol::equals(const char* str, int len) const {
73 int l = utf8_length();
74 if (l != len) return false;
75 while (l-- > 0) {
76 if (str[l] != (char) byte_at(l))
77 return false;
78 }
79 assert(l == -1, "we should be at the beginning");
80 return true;
81 }
82
83
84 // ------------------------------------------------------------------
85 // Symbol::starts_with
86 //
87 // Tests if the symbol starts with the specified prefix of the given
88 // length.
89 bool Symbol::starts_with(const char* prefix, int len) const {
90 if (len > utf8_length()) return false;
91 while (len-- > 0) {
92 if (prefix[len] != (char) byte_at(len))
93 return false;
94 }
95 assert(len == -1, "we should be at the beginning");
96 return true;
97 }
98
99
100 // ------------------------------------------------------------------
101 // Symbol::ends_with
102 //
103 // Tests if the symbol ends with the specified suffix of the given
104 // length.
105 bool Symbol::ends_with(const char* suffix, int len) const {
106 const int utf8_len = utf8_length();
107 if (len > utf8_len) return false;
108 int pos = utf8_len;
109 while (len-- > 0) {
110 pos--;
111 if (suffix[len] != (char) byte_at(pos))
112 return false;
113 }
114 assert(len == -1, "we should be at the beginning");
115 return true;
116 }
117
118
119 // ------------------------------------------------------------------
120 // Symbol::index_of
121 //
122 // Finds if the given string is a substring of this symbol's utf8 bytes.
123 // Return -1 on failure. Otherwise return the first index where str occurs.
124 int Symbol::index_of_at(int i, const char* str, int len) const {
125 assert(i >= 0 && i <= utf8_length(), "oob");
126 if (len <= 0) return 0;
127 char first_char = str[0];
128 address bytes = (address) ((Symbol*)this)->base();
129 address limit = bytes + utf8_length() - len; // inclusive limit
130 address scan = bytes + i;
131 if (scan > limit)
132 return -1;
133 for (; scan <= limit; scan++) {
134 scan = (address) memchr(scan, first_char, (limit + 1 - scan));
135 if (scan == NULL)
136 return -1; // not found
137 assert(scan >= bytes+i && scan <= limit, "scan oob");
138 if (memcmp(scan, str, len) == 0)
139 return (int)(scan - bytes);
140 }
141 return -1;
142 }
143
144
145 char* Symbol::as_C_string(char* buf, int size) const {
146 if (size > 0) {
147 int len = MIN2(size - 1, utf8_length());
148 for (int i = 0; i < len; i++) {
149 buf[i] = byte_at(i);
150 }
151 buf[len] = '\0';
152 }
153 return buf;
154 }
155
156 char* Symbol::as_C_string() const {
157 int len = utf8_length();
158 char* str = NEW_RESOURCE_ARRAY(char, len + 1);
159 return as_C_string(str, len + 1);
160 }
161
162 char* Symbol::as_C_string_flexible_buffer(Thread* t,
163 char* buf, int size) const {
164 char* str;
165 int len = utf8_length();
166 int buf_len = len + 1;
167 if (size < buf_len) {
168 str = NEW_RESOURCE_ARRAY(char, buf_len);
169 } else {
170 str = buf;
171 }
172 return as_C_string(str, buf_len);
173 }
174
175 void Symbol::print_utf8_on(outputStream* st) const {
176 st->print("%s", as_C_string());
177 }
178
179 void Symbol::print_symbol_on(outputStream* st) const {
180 char *s;
181 st = st ? st : tty;
182 {
183 // ResourceMark may not affect st->print(). If st is a string
184 // stream it could resize, using the same resource arena.
185 ResourceMark rm;
186 s = as_quoted_ascii();
187 s = os::strdup(s);
188 }
189 if (s == NULL) {
190 st->print("(null)");
191 } else {
192 st->print("%s", s);
193 os::free(s);
194 }
195 }
196
197 char* Symbol::as_quoted_ascii() const {
198 const char *ptr = (const char *)&_body[0];
199 int quoted_length = UTF8::quoted_ascii_length(ptr, utf8_length());
200 char* result = NEW_RESOURCE_ARRAY(char, quoted_length + 1);
201 UTF8::as_quoted_ascii(ptr, utf8_length(), result, quoted_length + 1);
202 return result;
203 }
204
205 jchar* Symbol::as_unicode(int& length) const {
206 Symbol* this_ptr = (Symbol*)this;
207 length = UTF8::unicode_length((char*)this_ptr->bytes(), utf8_length());
208 jchar* result = NEW_RESOURCE_ARRAY(jchar, length);
209 if (length > 0) {
210 UTF8::convert_to_unicode((char*)this_ptr->bytes(), result, length);
211 }
212 return result;
213 }
214
215 const char* Symbol::as_klass_external_name(char* buf, int size) const {
216 if (size > 0) {
217 char* str = as_C_string(buf, size);
218 int length = (int)strlen(str);
219 // Turn all '/'s into '.'s (also for array klasses)
220 for (int index = 0; index < length; index++) {
221 if (str[index] == '/') {
222 str[index] = '.';
223 }
224 }
225 return str;
226 } else {
227 return buf;
228 }
229 }
230
231 const char* Symbol::as_klass_external_name() const {
232 char* str = as_C_string();
233 int length = (int)strlen(str);
234 // Turn all '/'s into '.'s (also for array klasses)
235 for (int index = 0; index < length; index++) {
236 if (str[index] == '/') {
237 str[index] = '.';
238 }
239 }
240 return str;
241 }
242
243 // Alternate hashing for unbalanced symbol tables.
244 unsigned int Symbol::new_hash(juint seed) {
245 ResourceMark rm;
246 // Use alternate hashing algorithm on this symbol.
247 return AltHashing::murmur3_32(seed, (const jbyte*)as_C_string(), utf8_length());
248 }
249
250 void Symbol::increment_refcount() {
251 // Only increment the refcount if non-negative. If negative either
252 // overflow has occurred or it is a permanent symbol in a read only
253 // shared archive.
254 if (_refcount >= 0) { // not a permanent symbol
255 Atomic::inc(&_refcount);
256 NOT_PRODUCT(Atomic::inc(&_total_count);)
257 }
258 }
259
260 void Symbol::decrement_refcount() {
261 if (_refcount >= 0) { // not a permanent symbol
262 jshort new_value = Atomic::add(-1, &_refcount);
263 #ifdef ASSERT
264 if (new_value == -1) { // we have transitioned from 0 -> -1
265 print();
266 assert(false, "reference count underflow for symbol");
267 }
268 #endif
269 (void)new_value;
270 }
271 }
272
273 void Symbol::print_on(outputStream* st) const {
274 if (this == NULL) {
275 st->print_cr("NULL");
276 } else {
277 st->print("Symbol: '");
278 print_symbol_on(st);
279 st->print("'");
280 st->print(" count %d", refcount());
281 }
282 }
283
284 // The print_value functions are present in all builds, to support the
285 // disassembler and error reporting.
286 void Symbol::print_value_on(outputStream* st) const {
287 if (this == NULL) {
288 st->print("NULL");
289 } else {
290 st->print("'");
291 for (int i = 0; i < utf8_length(); i++) {
292 st->print("%c", byte_at(i));
293 }
294 st->print("'");
295 }
296 }
297
298 // SymbolTable prints this in its statistics
299 NOT_PRODUCT(int Symbol::_total_count = 0;)