1 /*
2 * Copyright (c) 1997, 2017, 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 "logging/log.hpp"
30 #include "logging/logStream.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "oops/symbol.hpp"
34 #include "runtime/atomic.hpp"
35 #include "runtime/os.hpp"
36
37 Symbol::Symbol(const u1* name, int length, int refcount) {
38 _refcount = refcount;
39 _length = length;
40 _identity_hash = (short)os::random();
41 for (int i = 0; i < _length; i++) {
42 byte_at_put(i, name[i]);
43 }
44 }
45
46 void* Symbol::operator new(size_t sz, int len, TRAPS) throw() {
47 int alloc_size = size(len)*wordSize;
48 address res = (address) AllocateHeap(alloc_size, mtSymbol);
49 return res;
50 }
51
52 void* Symbol::operator new(size_t sz, int len, Arena* arena, TRAPS) throw() {
53 int alloc_size = size(len)*wordSize;
54 address res = (address)arena->Amalloc_4(alloc_size);
55 return res;
56 }
57
58 void Symbol::operator delete(void *p) {
59 assert(((Symbol*)p)->refcount() == 0, "should not call this");
60 FreeHeap(p);
61 }
62
63 // ------------------------------------------------------------------
64 // Symbol::starts_with
65 //
66 // Tests if the symbol starts with the specified prefix of the given
67 // length.
68 bool Symbol::starts_with(const char* prefix, int len) const {
69 if (len > utf8_length()) return false;
70 while (len-- > 0) {
71 if (prefix[len] != (char) byte_at(len))
72 return false;
73 }
74 assert(len == -1, "we should be at the beginning");
75 return true;
76 }
77
78
79 // ------------------------------------------------------------------
80 // Symbol::index_of
81 //
82 // Finds if the given string is a substring of this symbol's utf8 bytes.
83 // Return -1 on failure. Otherwise return the first index where str occurs.
84 int Symbol::index_of_at(int i, const char* str, int len) const {
85 assert(i >= 0 && i <= utf8_length(), "oob");
86 if (len <= 0) return 0;
87 char first_char = str[0];
88 address bytes = (address) ((Symbol*)this)->base();
89 address limit = bytes + utf8_length() - len; // inclusive limit
90 address scan = bytes + i;
91 if (scan > limit)
92 return -1;
93 for (; scan <= limit; scan++) {
94 scan = (address) memchr(scan, first_char, (limit + 1 - scan));
95 if (scan == NULL)
96 return -1; // not found
97 assert(scan >= bytes+i && scan <= limit, "scan oob");
98 if (memcmp(scan, str, len) == 0)
99 return (int)(scan - bytes);
100 }
101 return -1;
102 }
103
104
105 char* Symbol::as_C_string(char* buf, int size) const {
106 if (size > 0) {
107 int len = MIN2(size - 1, utf8_length());
108 for (int i = 0; i < len; i++) {
109 buf[i] = byte_at(i);
110 }
111 buf[len] = '\0';
112 }
113 return buf;
114 }
115
116 char* Symbol::as_C_string() const {
117 int len = utf8_length();
118 char* str = NEW_RESOURCE_ARRAY(char, len + 1);
119 return as_C_string(str, len + 1);
120 }
121
122 char* Symbol::as_C_string_flexible_buffer(Thread* t,
123 char* buf, int size) const {
124 char* str;
125 int len = utf8_length();
126 int buf_len = len + 1;
127 if (size < buf_len) {
128 str = NEW_RESOURCE_ARRAY(char, buf_len);
129 } else {
130 str = buf;
131 }
132 return as_C_string(str, buf_len);
133 }
134
135 void Symbol::print_utf8_on(outputStream* st) const {
136 st->print("%s", as_C_string());
137 }
138
139 void Symbol::print_symbol_on(outputStream* st) const {
140 char *s;
141 st = st ? st : tty;
142 {
143 // ResourceMark may not affect st->print(). If st is a string
144 // stream it could resize, using the same resource arena.
145 ResourceMark rm;
146 s = as_quoted_ascii();
147 s = os::strdup(s);
148 }
149 if (s == NULL) {
150 st->print("(null)");
151 } else {
152 st->print("%s", s);
153 os::free(s);
154 }
155 }
156
157 char* Symbol::as_quoted_ascii() const {
158 const char *ptr = (const char *)&_body[0];
159 int quoted_length = UTF8::quoted_ascii_length(ptr, utf8_length());
160 char* result = NEW_RESOURCE_ARRAY(char, quoted_length + 1);
161 UTF8::as_quoted_ascii(ptr, utf8_length(), result, quoted_length + 1);
162 return result;
163 }
164
165 jchar* Symbol::as_unicode(int& length) const {
166 Symbol* this_ptr = (Symbol*)this;
167 length = UTF8::unicode_length((char*)this_ptr->bytes(), utf8_length());
168 jchar* result = NEW_RESOURCE_ARRAY(jchar, length);
169 if (length > 0) {
170 UTF8::convert_to_unicode((char*)this_ptr->bytes(), result, length);
171 }
172 return result;
173 }
174
175 const char* Symbol::as_klass_external_name(char* buf, int size) const {
176 if (size > 0) {
177 char* str = as_C_string(buf, size);
178 int length = (int)strlen(str);
179 // Turn all '/'s into '.'s (also for array klasses)
180 for (int index = 0; index < length; index++) {
181 if (str[index] == '/') {
182 str[index] = '.';
183 }
184 }
185 return str;
186 } else {
187 return buf;
188 }
189 }
190
191 const char* Symbol::as_klass_external_name() const {
192 char* str = as_C_string();
193 int length = (int)strlen(str);
194 // Turn all '/'s into '.'s (also for array klasses)
195 for (int index = 0; index < length; index++) {
196 if (str[index] == '/') {
197 str[index] = '.';
198 }
199 }
200 return str;
201 }
202
203 // Alternate hashing for unbalanced symbol tables.
204 unsigned int Symbol::new_hash(juint seed) {
205 ResourceMark rm;
206 // Use alternate hashing algorithm on this symbol.
207 return AltHashing::murmur3_32(seed, (const jbyte*)as_C_string(), utf8_length());
208 }
209
210 void Symbol::increment_refcount() {
211 // Only increment the refcount if non-negative. If negative either
212 // overflow has occurred or it is a permanent symbol in a read only
213 // shared archive.
214 if (_refcount >= 0) { // not a permanent symbol
215 Atomic::inc(&_refcount);
216 NOT_PRODUCT(Atomic::inc(&_total_count);)
217 }
218 }
219
220 void Symbol::decrement_refcount() {
221 if (_refcount >= 0) { // not a permanent symbol
222 short new_value = Atomic::add(short(-1), &_refcount);
223 #ifdef ASSERT
224 if (new_value == -1) { // we have transitioned from 0 -> -1
225 print();
226 assert(false, "reference count underflow for symbol");
227 }
228 #endif
229 (void)new_value;
230 }
231 }
232
233 void Symbol::metaspace_pointers_do(MetaspaceClosure* it) {
234 if (log_is_enabled(Trace, cds)) {
235 LogStream trace_stream(Log(cds)::trace());
236 trace_stream.print("Iter(Symbol): %p ", this);
237 print_value_on(&trace_stream);
238 trace_stream.cr();
239 }
240 }
241
242 void Symbol::print_on(outputStream* st) const {
243 if (this == NULL) {
244 st->print_cr("NULL");
245 } else {
246 st->print("Symbol: '");
247 print_symbol_on(st);
248 st->print("'");
249 st->print(" count %d", refcount());
250 }
251 }
252
253 // The print_value functions are present in all builds, to support the
254 // disassembler and error reporting.
255 void Symbol::print_value_on(outputStream* st) const {
256 if (this == NULL) {
257 st->print("NULL");
258 } else {
259 st->print("'");
260 for (int i = 0; i < utf8_length(); i++) {
261 st->print("%c", byte_at(i));
262 }
263 st->print("'");
264 }
265 }
266
267 // SymbolTable prints this in its statistics
268 NOT_PRODUCT(int Symbol::_total_count = 0;)