test-suite/hash.c

   1
   2 /*
   3  * DEBUG: section 00    Hash Tables
   4  * AUTHOR: Harvest Derived
   5  *
   6  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   7  * ----------------------------------------------------------
   8  *
   9  *  Squid is the result of efforts by numerous individuals from
  10  *  the Internet community; see the CONTRIBUTORS file for full
  11  *  details.   Many organizations have provided support for Squid's
  12  *  development; see the SPONSORS file for full details.  Squid is
  13  *  Copyrighted (C) 2001 by the Regents of the University of
  14  *  California; see the COPYRIGHT file for full details.  Squid
  15  *  incorporates software developed and/or copyrighted by other
  16  *  sources; see the CREDITS file for full details.
  17  *
  18  *  This program is free software; you can redistribute it and/or modify
  19  *  it under the terms of the GNU General Public License as published by
  20  *  the Free Software Foundation; either version 2 of the License, or
  21  *  (at your option) any later version.
  22  *
  23  *  This program is distributed in the hope that it will be useful,
  24  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  25  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26  *  GNU General Public License for more details.
  27  *
  28  *  You should have received a copy of the GNU General Public License
  29  *  along with this program; if not, write to the Free Software
  30  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  31  *
  32  */
  33 #include "squid.h"
  34
  35 #if HAVE_UNISTD_H
  36 #include <unistd.h>
  37 #endif
  38 #if HAVE_CTYPE_H
  39 #include <ctype.h>
  40 #endif
  41 #if HAVE_STRINGS_H
  42 #include <strings.h>
  43 #endif
  44 #if HAVE_ASSERT_H
  45 #include <assert.h>
  46 #endif
  47
  48 #include "hash.h"
  49
  50 #undef free
  51 extern void my_free(char *, int, void *);
  52
  53 #define free(a) my_free(__FILE__, __LINE__, a)
  54
  55 extern void print_stats();
  56 /*
  57  *  hash_url() - Returns a well-distributed hash function for URLs.
  58  *  The best way is to sum up the last half of the string.
  59  *  Adapted from code written by Mic Bowman.  -Darren
  60  *  Generates a standard deviation = 15.73
  61  */
  62 unsigned int
  63 hash_url(const void *data, unsigned int size)
  64 {
  65     const char *s = data;
  66     unsigned int i, j, n;
  67     j = strlen(s);
  68     for (i = j / 2, n = 0; i < j; i++)
  69         n ^= 271 * (unsigned) s[i];
  70     i = n ^ (j * 271);
  71     return i % size;
  72 }
  73
  74 unsigned int
  75 hash_string(const void *data, unsigned int size)
  76 {
  77     const char *s = data;
  78     unsigned int n = 0;
  79     unsigned int j = 0;
  80     unsigned int i = 0;
  81     while (*s) {
  82         j++;
  83         n ^= 271 * (unsigned) *s++;
  84     }
  85     i = n ^ (j * 271);
  86     return i % size;
  87 }
  88
  89 /* the following 4 functions were adapted from
  90  *    usr/src/lib/libc/db/hash_func.c, 4.4 BSD lite */
  91
  92 /*
  93  * HASH FUNCTIONS
  94  *
  95  * Assume that we've already split the bucket to which this key hashes,
  96  * calculate that bucket, and check that in fact we did already split it.
  97  *
  98  * This came from ejb's hsearch.
  99  */
 100
 101 #define PRIME1          37
 102 #define PRIME2          1048583
 103
 104 /* Hash function from Chris Torek. */
 105 unsigned int
 106 hash4(const void *data, unsigned int size)
 107 {
 108     const char *key = data;
 109     size_t loop;
 110     unsigned int h;
 111     size_t len;
 112
 113 #define HASH4a   h = (h << 5) - h + *key++;
 114 #define HASH4b   h = (h << 5) + h + *key++;
 115 #define HASH4 HASH4b
 116
 117     h = 0;
 118     len = strlen(key);
 119     loop = (len + 8 - 1) >> 3;
 120     switch (len & (8 - 1)) {
 121     case 0:
 122         do {
 123             HASH4;
 124             /* FALLTHROUGH */
 125         case 7:
 126             HASH4;
 127             /* FALLTHROUGH */
 128         case 6:
 129             HASH4;
 130             /* FALLTHROUGH */
 131         case 5:
 132             HASH4;
 133             /* FALLTHROUGH */
 134         case 4:
 135             HASH4;
 136             /* FALLTHROUGH */
 137         case 3:
 138             HASH4;
 139             /* FALLTHROUGH */
 140         case 2:
 141             HASH4;
 142             /* FALLTHROUGH */
 143         case 1:
 144             HASH4;
 145         } while (--loop);
 146     }
 147     return h % size;
 148 }
 149
 150 /*
 151  *  hash_create - creates a new hash table, uses the cmp_func
 152  *  to compare keys.  Returns the identification for the hash table;
 153  *  otherwise returns a negative number on error.
 154  */
 155 hash_table *
 156 hash_create(HASHCMP * cmp_func, int hash_sz, HASHHASH * hash_func)
 157 {
 158     hash_table *hid = calloc(1, sizeof(hash_table));
 159     if (!hash_sz)
 160         hid->size = (unsigned int) DEFAULT_HASH_SIZE;
 161     else
 162         hid->size = (unsigned int) hash_sz;
 163     /* allocate and null the buckets */
 164     hid->buckets = calloc(hid->size, sizeof(hash_link *));
 165     hid->cmp = cmp_func;
 166     hid->hash = hash_func;
 167     hid->current_ptr = NULL;
 168     hid->current_slot = 0;
 169     return hid;
 170 }
 171
 172 /*
 173  *  hash_insert - inserts the given item 'item' under the given key 'k'
 174  *  into the hash table 'hid'.  Returns non-zero on error; otherwise,
 175  *  returns 0 and inserts the item.
 176  *
 177  *  It does not copy any data into the hash table, only pointers.
 178  */
 179 void
 180 hash_insert(hash_table * hid, const char *k, void *item)
 181 {
 182     int i;
 183     hash_link *new;
 184     assert(k != NULL);
 185     /* Add to the given hash table 'hid' */
 186     new = calloc(1, sizeof(hash_link));
 187     if (!new) {
 188         fprintf(stderr, "calloc failed!\n");
 189         print_stats();
 190         exit(1);
 191     }
 192     new->item = item;
 193     new->key = (char *) k;
 194     i = hid->hash(k, hid->size);
 195     new->next = hid->buckets[i];
 196     hid->buckets[i] = new;
 197 }
 198
 199 /*
 200  *  hash_join - joins a hash_link under its key lnk->key
 201  *  into the hash table 'hid'.
 202  *
 203  *  It does not copy any data into the hash table, only links pointers.
 204  */
 205 void
 206 hash_join(hash_table * hid, hash_link * lnk)
 207 {
 208     int i;
 209     i = hid->hash(lnk->key, hid->size);
 210     lnk->next = hid->buckets[i];
 211     hid->buckets[i] = lnk;
 212 }
 213
 214 /*
 215  *  hash_lookup - locates the item under the key 'k' in the hash table
 216  *  'hid'.  Returns a pointer to the hash bucket on success; otherwise
 217  *  returns NULL.
 218  */
 219 hash_link *
 220 hash_lookup(hash_table * hid, const void *k)
 221 {
 222     hash_link *walker;
 223     int b;
 224     assert(k != NULL);
 225     b = hid->hash(k, hid->size);
 226     for (walker = hid->buckets[b]; walker != NULL; walker = walker->next) {
 227         if ((hid->cmp) (k, walker->key) == 0)
 228             return (walker);
 229         assert(walker != walker->next);
 230     }
 231     return NULL;
 232 }
 233
 234 /*
 235  *  hash_first - returns the first item in the hash table 'hid'.
 236  *  Otherwise, returns NULL on error.
 237  */
 238 hash_link *
 239 hash_first(hash_table * hid)
 240 {
 241     int i;
 242
 243     for (i = 0; i < hid->size; i++) {
 244         hid->current_slot = i;
 245         if (hid->buckets[i] != NULL)
 246             return (hid->current_ptr = hid->buckets[i]);
 247     }
 248     return NULL;
 249 }
 250
 251 /*
 252  *  hash_next - returns the next item in the hash table 'hid'.
 253  *  Otherwise, returns NULL on error or end of list.
 254  *
 255  *  MUST call hash_first() before hash_next().
 256  */
 257 hash_link *
 258 hash_next(hash_table * hid)
 259 {
 260     int i;
 261
 262     if (hid->current_ptr != NULL) {
 263         hid->current_ptr = hid->current_ptr->next;
 264         if (hid->current_ptr != NULL)
 265             return (hid->current_ptr);  /* next item */
 266     }
 267     /* find next bucket */
 268     for (i = hid->current_slot + 1; i < hid->size; i++) {
 269         hid->current_slot = i;
 270         if (hid->buckets[i] != NULL)
 271             return (hid->current_ptr = hid->buckets[i]);
 272     }
 273     return NULL;                /* end of list */
 274 }
 275
 276 int
 277 hash_delete(hash_table * hid, const char *key)
 278 {
 279     return hash_delete_link(hid, hash_lookup(hid, key));
 280 }
 281
 282 /*
 283  *  hash_delete_link - deletes the given hash_link node from the
 284  *  hash table 'hid'. If FreeLink then free the given hash_link.
 285  *
 286  *  On success, it returns 0 and deletes the link; otherwise,
 287  *  returns non-zero on error.
 288  */
 289 int
 290 hash_unlink(hash_table * hid, hash_link * hl, int FreeLink)
 291 {
 292     hash_link *walker, *prev;
 293     int i;
 294     if (hl == NULL)
 295         return -1;
 296     i = hid->hash(hl->key, hid->size);
 297     for (prev = NULL, walker = hid->buckets[i];
 298             walker != NULL; prev = walker, walker = walker->next) {
 299         if (walker == hl) {
 300             if (prev == NULL) { /* it's the head */
 301                 hid->buckets[i] = walker->next;
 302             } else {
 303                 prev->next = walker->next;      /* skip it */
 304             }
 305             /* fix walker state if needed */
 306             if (walker == hid->current_ptr)
 307                 hid->current_ptr = walker->next;
 308             if (FreeLink) {
 309                 if (walker) {
 310                     free(walker);
 311                 }
 312             }
 313             return 0;
 314         }
 315     }
 316     return 1;
 317 }
 318
 319 /* take link off and free link node */
 320 int
 321 hash_delete_link(hash_table * hid, hash_link * hl)
 322 {
 323     return (hash_unlink(hid, hl, 1));
 324 }
 325
 326 /* take link off only */
 327 int
 328 hash_remove_link(hash_table * hid, hash_link * hl)
 329 {
 330     return (hash_unlink(hid, hl, 0));
 331 }
 332
 333 /*
 334  *  hash_get_bucket - returns the head item of the bucket
 335  *  in the hash table 'hid'. Otherwise, returns NULL on error.
 336  */
 337 hash_link *
 338 hash_get_bucket(hash_table * hid, unsigned int bucket)
 339 {
 340     if (bucket >= hid->size)
 341         return NULL;
 342     return (hid->buckets[bucket]);
 343 }
 344
 345 void
 346 hashFreeMemory(hash_table * hid)
 347 {
 348     if (hid->buckets);
 349     free(hid->buckets);
 350     if (hid)
 351         free(hid);
 352 }
 353
 354 #if USE_HASH_DRIVER
 355 /*
 356  *  hash-driver - Run with a big file as stdin to insert each line into the
 357  *  hash table, then prints the whole hash table, then deletes a random item,
 358  *  and prints the table again...
 359  */
 360 int
 361 main(void)
 362 {
 363     hash_table *hid;
 364     int i;
 365     LOCAL_ARRAY(char, buf, BUFSIZ);
 366     LOCAL_ARRAY(char, todelete, BUFSIZ);
 367     hash_link *walker = NULL;
 368
 369     todelete[0] = '\0';
 370     printf("init\n");
 371
 372     printf("creating hash table\n");
 373     if ((hid = hash_create(strcmp, 229, hash_string)) < 0) {
 374         printf("hash_create error.\n");
 375         exit(1);
 376     }
 377     printf("done creating hash table: %d\n", hid);
 378
 379     while (fgets(buf, BUFSIZ, stdin)) {
 380         buf[strlen(buf) - 1] = '\0';
 381         printf("Inserting '%s' for item %p to hash table: %d\n",
 382                buf, buf, hid);
 383         hash_insert(hid, xstrdup(buf), (void *) 0x12345678);
 384         if (random() % 17 == 0)
 385             strcpy(todelete, buf);
 386     }
 387
 388     printf("walking hash table...\n");
 389     for (i = 0, walker = hash_first(hid); walker; walker = hash_next(hid)) {
 390         printf("item %5d: key: '%s' item: %p\n", i++, walker->key,
 391                walker->item);
 392     }
 393     printf("done walking hash table...\n");
 394
 395     if (todelete[0]) {
 396         printf("deleting %s from %d\n", todelete, hid);
 397         if (hash_delete(hid, todelete))
 398             printf("hash_delete error\n");
 399     }
 400     printf("walking hash table...\n");
 401     for (i = 0, walker = hash_first(hid); walker; walker = hash_next(hid)) {
 402         printf("item %5d: key: '%s' item: %p\n", i++, walker->key,
 403                walker->item);
 404     }
 405     printf("done walking hash table...\n");
 406
 407     printf("driver finished.\n");
 408     exit(0);
 409 }
 410 #endif