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Comparing deliantra/server/common/shstr.C (file contents):
Revision 1.2 by root, Tue Aug 29 08:01:36 2006 UTC vs.
Revision 1.3 by root, Sun Sep 3 00:18:40 2006 UTC

1/* 1/*
2 * static char *rcsid_shstr_c =
3 * "$Id: shstr.C,v 1.2 2006/08/29 08:01:36 root Exp $";
4 *
5 * shstr.c 2 * shstr.C
6 *
7 * This is a simple shared strings package with a simple interface.
8 *
9 * char *find_string(const char *str)
10 * char *add_string(const char *str)
11 * char *add_refcount(char *str)
12 * void free_string(char *str)
13 * char *ss_dump_table(int what)
14 * void ss_dump_statistics()
15 *
16 * Author: Kjetil T. Homme, Oslo 1992.
17 */ 3 */
18 4
19#include <stdio.h>
20#include <stddef.h>
21#include <stdlib.h>
22#include <sys/types.h>
23#include <limits.h>
24#include <string.h> 5#include <cstring>
6#include <cstdlib>
25 7
26#if defined (__sun__) && defined (StupidSunHeaders) 8#include <tr1/unordered_set>
27#include <sys/time.h>
28#include "sunos.h"
29#endif
30 9
31#include "shstr.h" 10#include "shstr.h"
32 11
33#ifndef WIN32 12struct hash
34#include <autoconf.h> 13{
35#endif 14 std::size_t operator ()(const char *s) const
36#ifdef HAVE_LIBDMALLOC 15 {
37#include <dmalloc.h> 16 unsigned long hash = 0;
38#endif 17 unsigned int i = 0;
39 18
40static shared_string *hash_table[TABLESIZE]; 19 /* use the one-at-a-time hash function, which supposedly is
20 * better than the djb2-like one used by perl5.005, but
21 * certainly is better then the bug used here before.
22 * see http://burtleburtle.net/bob/hash/doobs.html
23 */
24 while (*s)
25 {
26 hash += *s++;
27 hash += hash << 10;
28 hash ^= hash >> 6;
29 }
41 30
42/* 31 hash += hash << 3;
43 * Initialises the hash-table used by the shared string library. 32 hash ^= hash >> 11;
44 */ 33 hash += hash << 15;
45 34
46void 35 return hash;
47init_hash_table(void) { 36 }
48 /* A static object should be zeroed out always */ 37};
49#if !defined(__STDC__) 38
50 (void) memset((void *)hash_table, 0, TABLESIZE * sizeof(shared_string *)); 39struct equal
51#endif 40{
41 bool operator ()(const char *a, const char *b) const
42 {
43 return !strcmp (a, b);
44 }
45};
46
47typedef std::tr1::unordered_set<const char *, hash, equal> HT;
48
49static HT ht;
50
51const char *
52shstr::find (const char *s)
53{
54 HT::iterator i = ht.find (s);
55
56 return i != ht.end ()
57 ? (char *)*i
58 : 0;
52} 59}
53 60
54/* 61const char *
55 * Hashing-function used by the shared string library. 62shstr::intern (const char *s)
56 */ 63{
64 HT::iterator i = ht.find (s);
57 65
58static int 66 if (i != ht.end ())
59hashstr(const char *str) { 67 return (char *)*i;
60 unsigned long hash = 0;
61 int i = 0;
62 unsigned rot = 0;
63 const char *p;
64 68
65 GATHER(hash_stats.calls); 69 int len = strlen (s);
66 70
67 for (p = str; i < MAXSTRING && *p; p++, i++) { 71 int *v = (int *)malloc (sizeof (int) * 2 + len + 1);
68 hash ^= (unsigned long) *p << rot; 72
69 rot += 2; 73 v [0] = len;
70 if (rot >= (sizeof(long) - sizeof(char)) * CHAR_BIT) 74 v [1] = 0;
71 rot = 0; 75
72 } 76 v += 2;
73 return (hash % TABLESIZE); 77
78 memcpy (v, s, len + 1);
79
80 ht.insert ((char *)v);
81
82 return (char *)v;
74} 83}
75 84
76/* 85// TODO: periodically test refcounts == 0 for a few strings (e.g. one hash bucket,
77 * Allocates and initialises a new shared_string structure, containing 86// exploiting the fatc that iterators stay valid for unordered_set).
78 * the string str.
79 */
80
81static shared_string *
82new_shared_string(const char *str) {
83 shared_string *ss;
84
85 /* Allocate room for a struct which can hold str. Note
86 * that some bytes for the string are already allocated in the
87 * shared_string struct.
88 */
89 ss = (shared_string *) malloc(sizeof(shared_string) - PADDING +
90 strlen(str) + 1);
91 ss->u.previous = NULL;
92 ss->next = NULL;
93 ss->refcount = 1;
94 strcpy(ss->string, str);
95
96 return ss;
97}
98
99/*
100 * Description:
101 * This will add 'str' to the hash table. If there's no entry for this
102 * string, a copy will be allocated, and a pointer to that is returned.
103 * Return values:
104 * - pointer to string identical to str
105 */
106
107const char *
108add_string(const char *str) {
109 shared_string *ss;
110 int ind;
111
112 GATHER(add_stats.calls);
113
114 /* Should really core dump here, since functions should not be calling
115 * add_string with a null parameter. But this will prevent a few
116 * core dumps.
117 */
118 if (str==NULL) {
119#ifdef MANY_CORES
120 abort();
121#else
122 return NULL;
123#endif
124 }
125
126 ind = hashstr(str);
127 ss = hash_table[ind];
128
129 /* Is there an entry for that hash?
130 */
131 if (ss) {
132 /* Simple case first: See if the first pointer matches.
133 */
134 if (str != ss->string) {
135 GATHER(add_stats.strcmps);
136 if (strcmp(ss->string, str)) {
137 /* Apparantly, a string with the same hash value has this
138 * slot. We must see in the list if "str" has been
139 * registered earlier.
140 */
141 while (ss->next) {
142 GATHER(add_stats.search);
143 ss = ss->next;
144 if (ss->string != str) {
145 GATHER(add_stats.strcmps);
146 if (strcmp(ss->string, str)) {
147 /* This wasn't the right string...
148 */
149 continue;
150 }
151 }
152 /* We found an entry for this string. Fix the
153 * refcount and exit.
154 */
155 GATHER(add_stats.linked);
156 ++(ss->refcount);
157
158 return ss->string;
159 }
160 /* There are no occurences of this string in the hash table.
161 */
162 {
163 shared_string *new_ss;
164
165 GATHER(add_stats.linked);
166 new_ss = new_shared_string(str);
167 ss->next = new_ss;
168 new_ss->u.previous = ss;
169 return new_ss->string;
170 }
171 }
172 /* Fall through.
173 */
174 }
175 GATHER(add_stats.hashed);
176 ++(ss->refcount);
177 return ss->string;
178 } else {
179 /* The string isn't registered, and the slot is empty.
180 */
181 GATHER(add_stats.hashed);
182 hash_table[ind] = new_shared_string(str);
183
184 /* One bit in refcount is used to keep track of the union.
185 */
186 hash_table[ind]->refcount |= TOPBIT;
187 hash_table[ind]->u.array = &(hash_table[ind]);
188
189 return hash_table[ind]->string;
190 }
191}
192
193/*
194 * Description:
195 * This will increase the refcount of the string str, which *must*
196 * have been returned from a previous add_string().
197 * Return values:
198 * - str
199 */
200
201const char *
202add_refcount(const char *str) {
203 GATHER(add_ref_stats.calls);
204 ++(SS(str)->refcount);
205 /* This function should be declared
206 * const char *add_refcount(const char *)
207 * Unfortunately, that would require changing a lot of structs
208 *
209 * Yup, many changes, but may have make some bugs more visible :)
210 * -- Ryo 2005-08-12
211 */
212 return (char*)str;
213}
214
215/*
216 * Description:
217 * This will return the refcount of the string str, which *must*
218 * have been returned from a previous add_string().
219 * Return values:
220 * - length
221 */
222
223int
224query_refcount(const char *str) {
225 return (SS(str)->refcount) & ~TOPBIT;
226}
227
228/*
229 * Description:
230 * This will see if str is in the hash table, and return the address
231 * of that string if it exists.
232 * Return values:
233 * - pointer to identical string or NULL
234 */
235
236const char *
237find_string(const char *str) {
238 shared_string *ss;
239 int ind;
240
241 GATHER(find_stats.calls);
242
243 ind = hashstr(str);
244 ss = hash_table[ind];
245
246 /* Is there an entry for that hash?
247 */
248 if (ss) {
249 /* Simple case first: Is the first string the right one?
250 */
251 GATHER(find_stats.strcmps);
252 if (!strcmp(ss->string, str)) {
253 GATHER(find_stats.hashed);
254 return ss->string;
255 } else {
256 /* Recurse through the linked list, if there's one.
257 */
258 while (ss->next) {
259 GATHER(find_stats.search);
260 GATHER(find_stats.strcmps);
261 ss = ss->next;
262 if (!strcmp(ss->string, str)) {
263 GATHER(find_stats.linked);
264 return ss->string;
265 }
266 }
267 /* No match. Fall through.
268 */
269 }
270 }
271 return NULL;
272}
273
274/*
275 * Description:
276 * This will reduce the refcount, and if it has reached 0, str will
277 * be freed.
278 * Return values:
279 * None
280 */
281
282void 87void
283free_string(const char *str) { 88shstr::gc ()
284 shared_string *ss; 89{
285
286 GATHER(free_stats.calls);
287
288 ss = SS(str);
289
290 if ((--ss->refcount & ~TOPBIT) == 0) {
291 /* Remove this entry.
292 */
293 if (ss->refcount & TOPBIT) {
294 /* We must put a new value into the hash_table[].
295 */
296 if (ss->next) {
297 *(ss->u.array) = ss->next;
298 ss->next->u.array = ss->u.array;
299 ss->next->refcount |= TOPBIT;
300 } else {
301 *(ss->u.array) = NULL;
302 }
303 free(ss);
304 } else {
305 /* Relink and free this struct.
306 */
307 if (ss->next)
308 ss->next->u.previous = ss->u.previous;
309 ss->u.previous->next = ss->next;
310 free(ss);
311 }
312 }
313}
314
315#ifdef SS_STATISTICS
316
317extern char errmsg[];
318
319/*
320 * Description:
321 * The routines will gather statistics if SS_STATISTICS is defined.
322 * A call to this function will cause the statistics to be dumped
323 * into an external string errmsg, which must be large.
324 * Return values:
325 * None
326 */
327
328void
329ss_dump_statistics(void) {
330 static char line[80];
331
332 sprintf(errmsg, "%-13s %6s %6s %6s %6s %6s\n",
333 "", "calls", "hashed", "strcmp", "search", "linked");
334 sprintf(line, "%-13s %6d %6d %6d %6d %6d\n",
335 "add_string:", add_stats.calls, add_stats.hashed,
336 add_stats.strcmps, add_stats.search, add_stats.linked);
337 strcat(errmsg, line);
338 sprintf(line, "%-13s %6d\n",
339 "add_refcount:", add_ref_stats.calls);
340 strcat(errmsg, line);
341 sprintf(line, "%-13s %6d\n",
342 "free_string:", free_stats.calls);
343 strcat(errmsg, line);
344 sprintf(line, "%-13s %6d %6d %6d %6d %6d\n",
345 "find_string:", find_stats.calls, find_stats.hashed,
346 find_stats.strcmps, find_stats.search, find_stats.linked);
347 strcat(errmsg, line);
348 sprintf(line, "%-13s %6d\n",
349 "hashstr:", hash_stats.calls);
350 strcat(errmsg, line);
351}
352#endif /* SS_STATISTICS */
353
354/*
355 * Description:
356 * If (what & SS_DUMP_TABLE) dump the contents of the hash table to
357 * stderr. If (what & SS_DUMP_TOTALS) return a string which
358 * says how many entries etc. there are in the table.
359 * Return values:
360 * - a string or NULL
361 */
362
363const char *
364ss_dump_table(int what) {
365 static char totals[80];
366 int entries = 0, refs = 0, links = 0;
367 int i;
368
369 for (i = 0; i < TABLESIZE; i++) {
370 shared_string *ss;
371
372 if ((ss = hash_table[i])!=NULL) {
373 ++entries;
374 refs += (ss->refcount & ~TOPBIT);
375#if 1 /* Can't use stderr any longer, need to include global.h and
376 if (what & SS_DUMP_TABLE)
377 * use logfile. */
378 fprintf(stderr, "%4d -- %4d refs '%s' %c\n",
379 i, (ss->refcount & ~TOPBIT), ss->string,
380 (ss->refcount & TOPBIT ? ' ' : '#'));
381#endif
382 while (ss->next) {
383 ss = ss->next;
384 ++links;
385 refs += (ss->refcount & ~TOPBIT);
386#if 1
387 if (what & SS_DUMP_TABLE)
388 fprintf(stderr, " -- %4d refs '%s' %c\n",
389 (ss->refcount & ~TOPBIT), ss->string,
390 (ss->refcount & TOPBIT ? '*' : ' '));
391#endif
392 }
393 }
394 }
395
396 if (what & SS_DUMP_TOTALS) {
397 sprintf(totals, "\n%d entries, %d refs, %d links.",
398 entries, refs, links);
399 return totals;
400 }
401 return NULL;
402} 90}
403 91
404/* buf_overflow() - we don't want to exceed the buffer size of 92/* buf_overflow() - we don't want to exceed the buffer size of
405 * buf1 by adding on buf2! Returns true if overflow will occur. 93 * buf1 by adding on buf2! Returns true if overflow will occur.
406 */ 94 */
407 95
408int 96int
409buf_overflow (const char *buf1, const char *buf2, int bufsize) 97buf_overflow (const char *buf1, const char *buf2, int bufsize)
410{ 98{
411 int len1 = 0, len2 = 0; 99 int len1 = 0, len2 = 0;
412 100
413 if (buf1) 101 if (buf1)
414 len1 = strlen (buf1); 102 len1 = strlen (buf1);
415 if (buf2) 103 if (buf2)
416 len2 = strlen (buf2); 104 len2 = strlen (buf2);

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