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Comparing deliantra/server/include/shstr.h (file contents):
Revision 1.2 by root, Sat Aug 26 23:36:32 2006 UTC vs.
Revision 1.27 by root, Wed Dec 31 18:29:44 2008 UTC

1/*
2 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
3 *
4 * Copyright (©) 2005,2006,2007,2008 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
5 *
6 * Deliantra is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 *
19 * The authors can be reached via e-mail to <support@deliantra.net>
20 */
21
1#ifndef SHSTR_H__ 22#ifndef SHSTR_H__
2#define SHSTR_H__ 23#define SHSTR_H__
3 24
4/* The size of the shared strings hashtable. This must be smaller than 25#include <cstring>
5 * 32767, but 947 ought to be plenty enough. 26#include <sstream>
6 */
7#define TABLESIZE 4133
8 27
9/* This specifies how many characters the hashing routine should look at. 28#include "traits.h"
10 * You may actually save CPU by increasing this number if the typical string 29
11 * is large. 30extern size_t shstr_alloc;
12 */ 31
13#ifndef MAXSTRING 32extern int buf_overflow (const char *buf1, const char *buf2, int bufsize);
14#define MAXSTRING 20 33
34template<int size>
35struct shstr_vec
36{
37 uint32_t len;
38 uint32_t refcnt;
39 char string[size];
40};
41
42// this class is a non-refcounted shared string
43// it cannot be used to create or store shared strings, but
44// it can be used to apss shared strings around, i.e. as function arguments
45// or return values. their lifetime must not span a gc () call, i.e.
46// they are only valid as temporary values within the same server tick.
47struct shstr_tmp
48{
49 static shstr_vec<sizeof ("(null)")> nullvec;
50 static const char *null () { return nullvec.string; } // this is the null pointer value
51
52 const char *s;
53
54 static unsigned int &length (const char *s)
55 {
56 return *((unsigned int *)s - 2);
57 }
58
59 int length () const
60 {
61 return length (s);
62 }
63
64 // returns whether this shared string begins with the given prefix,
65 // used mainly for searches when users give only the start of a name.
66 bool starts_with (const char *prefix) const
67 {
68 int plen = strlen (prefix);
69
70 return length () >= plen && !strncasecmp (s, prefix, plen);
71 }
72
73 bool contains (const char *substring) const
74 {
75 return strstr (s, substring);
76 }
77
78 shstr_tmp ()
79 : s (null ())
80 {
81 }
82
83 shstr_tmp (const shstr_tmp &sh)
84 : s (sh.s)
85 {
86 }
87
88 shstr_tmp operator =(const shstr_tmp &sh)
89 {
90 s = sh.s;
91
92 return *this;
93 }
94
95 // this is used for informational messages and the like
96 const char *operator &() const { return s; }
97
98 operator const char *() const { return s == null () ? 0 : s; }
99
100protected:
101 // dummy is there so it isn't used as type converter accidentally
102 shstr_tmp (int dummy, const char *s)
103 : s(s)
104 {
105 }
106};
107
108inline bool operator ==(const shstr_tmp &a, const shstr_tmp &b)
109{
110 return a.s == b.s;
111}
112
113inline bool operator !=(const shstr_tmp &a, const shstr_tmp &b)
114{
115 return a.s != b.s;
116}
117
118inline int strlen (const shstr_tmp &sh)
119{
120 return sh.length ();
121}
122
123// undefined external reference to catch people using strcmp when they shouldn't
124int strcmp (const shstr_tmp &a, const shstr_tmp &b);
125
126static std::ostream &operator <<(std::ostream &o, shstr_tmp sh)
127{
128 o.write (sh.s, sh.length ());
129
130 return o;
131}
132
133struct shstr : shstr_tmp
134{
135 static unsigned int &refcnt (const char *s)
136 {
137 return *((unsigned int *)s - 1);
138 }
139
140 unsigned int &refcnt () const
141 {
142 return refcnt (s);
143 }
144
145 shstr ()
146 {
147 }
148
149 static const char *find (const char *s);
150 static const char *intern (const char *s);
151
152 static void gc (); // garbage collect a few strings
153
154 shstr (const shstr &sh)
155 : shstr_tmp (sh)
156 {
157 ++refcnt ();
158 }
159
160 shstr (const shstr_tmp &sh)
161 : shstr_tmp (sh)
162 {
163 ++refcnt ();
164 }
165
166 explicit shstr (const char *str)
167 : shstr_tmp (0, is_constant (str) && !str ? null () : intern (str))
168 {
169 }
170
171 ~shstr ()
172 {
173 --refcnt ();
174 }
175
176 using shstr_tmp::operator &;
177 using shstr_tmp::operator const char *;
178
179 // (note: not the copy constructor)
180 shstr &operator =(const shstr_tmp &sh)
181 {
182 --refcnt ();
183 s = sh.s;
184 ++refcnt ();
185
186 return *this;
187 }
188
189 // here it comes
190 shstr &operator =(const shstr &sh)
191 {
192 return (*this) = (shstr_tmp)sh;
193 }
194
195 // shstr_tmp doesn't have this one
196 shstr &operator =(const char *str)
197 {
198 --refcnt ();
199 s = is_constant (str) && !str ? null () : intern (str);
200
201 return *this;
202 }
203};
204
205// only good for mass comparisons to shstr objects, or very
206// temporary passing, basically a non-refcounted shstr
207struct shstr_cmp
208{
209 const char *s;
210
211 explicit shstr_cmp (const char *str)
212 : s (shstr::find (str))
213 {
214 }
215
216 shstr_cmp (shstr_tmp sh)
217 : s (sh.s)
218 {
219 }
220
221 // this is used for informational messages and the like
222 const char *operator &() const { return s; }
223
224 operator const char *() const { return s; }
225};
226
227inline bool operator ==(const shstr_cmp &a, const shstr_tmp &b)
228{
229 return a.s == b.s;
230}
231
232inline bool operator ==(const shstr_tmp &a, const shstr_cmp &b)
233{
234 return a.s == b.s;
235}
236
237#define def(str) extern const shstr shstr_ ## str;
238# include "shstrinc.h"
239#undef def
240
15#endif 241#endif
16 242
17/* In the unlikely occurence that 16383 references to a string are too
18 * few, you can modify the below type to something bigger.
19 * (The top bit of "refcount" is used to signify that "u.array" points
20 * at the array entry.)
21 */
22#define REFCOUNT_TYPE int
23
24/* The offsetof macro is part of ANSI C, but many compilers lack it, for
25 * example "gcc -ansi"
26 */
27#if !defined (offsetof)
28#define offsetof(type, member) (int)&(((type *)0)->member)
29#endif
30
31/* SS(string) will return the address of the shared_string struct which
32 * contains "string".
33 */
34#define SS(x) ((shared_string *) ((x) - offsetof(shared_string, string)))
35
36#define SS_STATISTICS
37
38#define SS_DUMP_TABLE 1
39#define SS_DUMP_TOTALS 2
40
41#ifdef SS_STATISTICS
42static struct statistics {
43 int calls;
44 int hashed;
45 int strcmps;
46 int search;
47 int linked;
48} add_stats, add_ref_stats, free_stats, find_stats, hash_stats;
49#define GATHER(n) (++n)
50#else /* !SS_STATISTICS */
51#define GATHER(n)
52#endif /* SS_STATISTICS */
53
54#define TOPBIT ((unsigned REFCOUNT_TYPE) 1 << (sizeof(REFCOUNT_TYPE) * CHAR_BIT - 1))
55
56#define PADDING ((2 * sizeof(long) - sizeof(REFCOUNT_TYPE)) % sizeof(long)) + 1
57
58typedef struct _shared_string {
59 union {
60 struct _shared_string **array;
61 struct _shared_string *previous;
62 } u;
63 struct _shared_string *next;
64 /* The top bit of "refcount" is used to signify that "u.array" points
65 * at the array entry.
66 */
67 unsigned REFCOUNT_TYPE refcount;
68 /* Padding will be unused memory, since we can't know how large
69 * the padding when allocating memory. We assume here that
70 * sizeof(long) is a good boundary.
71 */
72 char string[PADDING];
73} shared_string;
74
75extern void init_hash_table(void);
76extern const char *add_string(const char *str);
77extern const char *add_refcount(const char *str);
78extern int query_refcount(const char *str);
79extern const char *find_string(const char *str);
80extern void free_string(const char *str);
81extern void ss_dump_statistics(void);
82extern const char *ss_dump_table(int what);
83extern int buf_overflow(const char *buf1, const char *buf2, int bufsize);
84
85#endif
86

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