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::starts_with
70 //
71 // Tests if the symbol starts with the specified prefix of the given
72 // length.
73 bool Symbol::starts_with(const char* prefix, int len) const {
74 if (len > utf8_length()) return false;
75 while (len-- > 0) {
76 if (prefix[len] != (char) byte_at(len))
77 return false;
78 }
79 assert(len == -1, "we should be at the beginning");
80 return true;
81 }
82
83
84 // ------------------------------------------------------------------
85 // Symbol::index_of
86 //
87 // Finds if the given string is a substring of this symbol's utf8 bytes.
88 // Return -1 on failure. Otherwise return the first index where str occurs.
89 int Symbol::index_of_at(int i, const char* str, int len) const {
90 assert(i >= 0 && i <= utf8_length(), "oob");
91 if (len <= 0) return 0;
92 char first_char = str[0];
93 address bytes = (address) ((Symbol*)this)->base();
94 address limit = bytes + utf8_length() - len; // inclusive limit
95 address scan = bytes + i;
96 if (scan > limit)
97 return -1;
98 for (; scan <= limit; scan++) {
99 scan = (address) memchr(scan, first_char, (limit + 1 - scan));
100 if (scan == NULL)
101 return -1; // not found
102 assert(scan >= bytes+i && scan <= limit, "scan oob");
103 if (memcmp(scan, str, len) == 0)
104 return (int)(scan - bytes);
105 }
106 return -1;
107 }
108
109
110 char* Symbol::as_C_string(char* buf, int size) const {
111 if (size > 0) {
112 int len = MIN2(size - 1, utf8_length());
113 for (int i = 0; i < len; i++) {
114 buf[i] = byte_at(i);
115 }
116 buf[len] = '\0';
117 }
118 return buf;
119 }
120
121 char* Symbol::as_C_string() const {
122 int len = utf8_length();
123 char* str = NEW_RESOURCE_ARRAY(char, len + 1);
124 return as_C_string(str, len + 1);
125 }
126
127 char* Symbol::as_C_string_flexible_buffer(Thread* t,
128 char* buf, int size) const {
129 char* str;
130 int len = utf8_length();
131 int buf_len = len + 1;
132 if (size < buf_len) {
133 str = NEW_RESOURCE_ARRAY(char, buf_len);
134 } else {
135 str = buf;
136 }
137 return as_C_string(str, buf_len);
138 }
139
140 void Symbol::print_utf8_on(outputStream* st) const {
141 st->print("%s", as_C_string());
142 }
143
144 void Symbol::print_symbol_on(outputStream* st) const {
145 char *s;
146 st = st ? st : tty;
147 {
148 // ResourceMark may not affect st->print(). If st is a string
149 // stream it could resize, using the same resource arena.
150 ResourceMark rm;
151 s = as_quoted_ascii();
152 s = os::strdup(s);
153 }
154 if (s == NULL) {
155 st->print("(null)");
156 } else {
157 st->print("%s", s);
158 os::free(s);
159 }
160 }
161
162 char* Symbol::as_quoted_ascii() const {
163 const char *ptr = (const char *)&_body[0];
164 int quoted_length = UTF8::quoted_ascii_length(ptr, utf8_length());
165 char* result = NEW_RESOURCE_ARRAY(char, quoted_length + 1);
166 UTF8::as_quoted_ascii(ptr, utf8_length(), result, quoted_length + 1);
167 return result;
168 }
169
170 jchar* Symbol::as_unicode(int& length) const {
171 Symbol* this_ptr = (Symbol*)this;
172 length = UTF8::unicode_length((char*)this_ptr->bytes(), utf8_length());
173 jchar* result = NEW_RESOURCE_ARRAY(jchar, length);
174 if (length > 0) {
175 UTF8::convert_to_unicode((char*)this_ptr->bytes(), result, length);
176 }
177 return result;
178 }
179
180 const char* Symbol::as_klass_external_name(char* buf, int size) const {
181 if (size > 0) {
182 char* str = as_C_string(buf, size);
183 int length = (int)strlen(str);
184 // Turn all '/'s into '.'s (also for array klasses)
185 for (int index = 0; index < length; index++) {
186 if (str[index] == '/') {
187 str[index] = '.';
188 }
189 }
190 return str;
191 } else {
192 return buf;
193 }
194 }
195
196 const char* Symbol::as_klass_external_name() const {
197 char* str = as_C_string();
198 int length = (int)strlen(str);
199 // Turn all '/'s into '.'s (also for array klasses)
200 for (int index = 0; index < length; index++) {
201 if (str[index] == '/') {
202 str[index] = '.';
203 }
204 }
205 return str;
206 }
207
208 // Alternate hashing for unbalanced symbol tables.
209 unsigned int Symbol::new_hash(juint seed) {
210 ResourceMark rm;
211 // Use alternate hashing algorithm on this symbol.
212 return AltHashing::murmur3_32(seed, (const jbyte*)as_C_string(), utf8_length());
213 }
214
215 void Symbol::increment_refcount() {
216 // Only increment the refcount if non-negative. If negative either
217 // overflow has occurred or it is a permanent symbol in a read only
218 // shared archive.
219 if (_refcount >= 0) { // not a permanent symbol
220 Atomic::inc(&_refcount);
221 NOT_PRODUCT(Atomic::inc(&_total_count);)
222 }
223 }
224
225 void Symbol::decrement_refcount() {
226 if (_refcount >= 0) { // not a permanent symbol
227 jshort new_value = Atomic::add(-1, &_refcount);
228 #ifdef ASSERT
229 if (new_value == -1) { // we have transitioned from 0 -> -1
230 print();
231 assert(false, "reference count underflow for symbol");
232 }
233 #endif
234 (void)new_value;
235 }
236 }
237
238 void Symbol::print_on(outputStream* st) const {
239 if (this == NULL) {
240 st->print_cr("NULL");
241 } else {
242 st->print("Symbol: '");
243 print_symbol_on(st);
244 st->print("'");
245 st->print(" count %d", refcount());
246 }
247 }
248
249 // The print_value functions are present in all builds, to support the
250 // disassembler and error reporting.
251 void Symbol::print_value_on(outputStream* st) const {
252 if (this == NULL) {
253 st->print("NULL");
254 } else {
255 st->print("'");
256 for (int i = 0; i < utf8_length(); i++) {
257 st->print("%c", byte_at(i));
258 }
259 st->print("'");
260 }
261 }
262
263 // SymbolTable prints this in its statistics
264 NOT_PRODUCT(int Symbol::_total_count = 0;)