aboutsummaryrefslogtreecommitdiffstats
path: root/src/htable.h
blob: efd7cacd50ff4691866d8e8c7bb4cdbc7981683b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
/*
 * Copyright (c) 2004-2011 calcurse Development Team <misc@calcurse.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the
 *        following disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the
 *        following disclaimer in the documentation and/or other
 *        materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef HTABLE_H
#define HTABLE_H

#include <stdint.h>
#include <string.h>

/*
 * This file defines data structures for hash tables.
 *
 * Hash tables are ideal for applications with datasets needing lots of adding,
 * searching or removal, as those are normally constant-time operations.
 * The primary operation it supports efficiently is a lookup: given a key (e.g.
 * a person's name), find the corresponding value (e.g. that person's telephone
 * number). It works by transforming the key using a hash function into a hash,
 * a number that is used as an index in an array to locate the desired location
 * ("bucket") where the values should be.
 *
 * Hash tables support the efficient insertion of new entries, in expected O(1)
 * time. The time spent in searching depends on the hash function and the load
 * of the hash table; both insertion and search approach O(1) time with well
 * chosen values and hashes.
 *
 * The collision resolution technique used here is direct chaining, implemented
 * using singly linked lists (the worst-case time is O(n)).
 *
 * This was chosen because performance degradation is linear as the table
 * fills, so there is almost no need to resize table
 * (for example, a chaining hash table containing twice its recommended
 * capacity of data would only be about twice as slow on average as the same
 * table at its recommended capacity).
 */

#define HTABLE_HEAD(name, size, type)                                         \
struct name {                                                                 \
  uint32_t      noitems;     /* Number of items stored in hash table. */      \
  uint32_t      nosingle;    /* Number of items alone in their bucket. */     \
  uint32_t      nofreebkts;  /* Number of free buckets. */                    \
  struct type  *bkts[size];  /* Pointers to user-defined data structures. */  \
}

#define HTABLE_ENTRY(type)                                                    \
struct type   *next          /* To build the bucket chain list. */

#define HTABLE_SIZE(head)                                                     \
  (sizeof (*(head)->bkts) ? sizeof ((head)->bkts) / sizeof (*(head)->bkts) : 0)

#define HTABLE_COUNT(head)                                                    \
  ((head)->noitems ? (head)->noitems : 0)

#define HTABLE_EMPTY(head)                                                    \
  (HTABLE_COUNT((head)) == 0 ? 1 : 0)

#define HTABLE_COLLS(head)                                                    \
  ((head)->noitems ? 100.0 - 100 * (head)->nosingle / (head)->noitems : 0)

#define HTABLE_LOAD(head)                                                     \
  (HTABLE_SIZE((head)) ?                                                      \
   100.0 - 100.0 * (head)->nofreebkts / HTABLE_SIZE((head)) : 0)

#define HTABLE_INITIALIZER(head)                                              \
  { 0,                    /* noitems */                                       \
    0,                    /* nosingle */                                      \
    HTABLE_SIZE((head))   /* nofreebkts */                                    \
  }

#define HTABLE_INIT(head) do {                                                \
  bzero ((head), sizeof (*(head)));                                           \
  (head)->nofreebkts = HTABLE_SIZE((head));                                   \
} while (0)

/*
 * Generate prototypes.
 */
#define HTABLE_PROTOTYPE(name, type)                                          \
struct type *name##_HTABLE_INSERT(struct name *, struct type *);              \
struct type *name##_HTABLE_REMOVE(struct name *, struct type *);              \
struct type *name##_HTABLE_LOOKUP(struct name *, struct type *);

/*
 * Generate function bodies.
 */
#define HTABLE_GENERATE(name, type, key, cmp)                                 \
uint32_t                                                                      \
name##_HTABLE_FIND_BKT(struct name *head, struct type *elm)                   \
{                                                                             \
  uint32_t __bkt;                                                             \
  char *__key;                                                                \
  int __len;                                                                  \
                                                                              \
  (key) (elm, &__key, &__len);                                                \
  HTABLE_HASH(__key, __len, HTABLE_SIZE(head), __bkt);                        \
                                                                              \
  return __bkt;                                                               \
}                                                                             \
                                                                              \
int                                                                           \
name##_HTABLE_CHAIN_LEN(struct name *head, uint32_t bkt)                      \
{                                                                             \
  struct type *__bktp;                                                        \
  int __len;                                                                  \
                                                                              \
  __len = 0;                                                                  \
  for (__bktp = (head)->bkts[(bkt)]; __bktp != NULL; __bktp = __bktp->next)   \
    __len++;                                                                  \
                                                                              \
  return __len;                                                               \
}                                                                             \
                                                                              \
struct type *                                                                 \
name##_HTABLE_INSERT(struct name *head, struct type *elm)                     \
{                                                                             \
  struct type *__bktp, **__bktpp;                                             \
  uint32_t __bkt, __pos;                                                      \
                                                                              \
  __pos = 0;                                                                  \
  __bkt = name##_HTABLE_FIND_BKT(head, elm);                                  \
  __bktpp = &head->bkts[__bkt];                                               \
  while ((__bktp = *__bktpp))                                                 \
    {                                                                         \
      if (!(cmp)(elm, __bktp))                                                \
        return NULL;                                                          \
      else                                                                    \
        {                                                                     \
          __pos++;                                                            \
          __bktpp = &__bktp->next;                                            \
        }                                                                     \
    }                                                                         \
  __bktp = elm;                                                               \
  __bktp->next = NULL;                                                        \
  *__bktpp = __bktp;                                                          \
  head->noitems++;                                                            \
  switch (__pos)                                                              \
    {                                                                         \
    case 0:                                                                   \
      head->nosingle++;                                                       \
      head->nofreebkts--;                                                     \
      break;                                                                  \
    case 1:                                                                   \
      head->nosingle--;                                                       \
      break;                                                                  \
    default:                                                                  \
      break;                                                                  \
    }                                                                         \
                                                                              \
  return __bktp;                                                              \
}                                                                             \
                                                                              \
struct type *                                                                 \
name##_HTABLE_REMOVE(struct name *head, struct type *elm)                     \
{                                                                             \
  struct type *__bktp, **__bktpp;                                             \
  uint32_t __bkt, __pos;                                                      \
                                                                              \
  __pos = 0;                                                                  \
  __bkt = name##_HTABLE_FIND_BKT(head, elm);                                  \
  __bktpp = &head->bkts[__bkt];                                               \
  while ((__bktp = *__bktpp))                                                 \
    {                                                                         \
      if (!(cmp)(elm, __bktp))                                                \
        {                                                                     \
          *__bktpp = __bktp->next;                                            \
          elm = __bktp;                                                       \
          head->noitems--;                                                    \
          if (__pos <= 1)      /* Need to scan list to know if we have */     \
            {                  /* a free bucket or a single item.      */     \
              int __len;                                                      \
                                                                              \
              __len = name##_HTABLE_CHAIN_LEN(head, __bkt);                   \
              switch (__len)                                                  \
                {                                                             \
                case 0:                                                       \
                  head->nofreebkts++;                                         \
                  head->nosingle--;                                           \
                  break;                                                      \
                case 1:                                                       \
                  head->nosingle++;                                           \
                  break;                                                      \
                }                                                             \
            }                                                                 \
          return elm;                                                         \
        }                                                                     \
      __pos++;                                                                \
      __bktpp = &__bktp->next;                                                \
    }                                                                         \
  return NULL;                                                                \
}                                                                             \
                                                                              \
struct type *                                                                 \
name##_HTABLE_LOOKUP(struct name *head, struct type *elm)                     \
{                                                                             \
  struct type *__bktp, **__bktpp;                                             \
  uint32_t __bkt;                                                             \
                                                                              \
  __bkt = name##_HTABLE_FIND_BKT(head, elm);                                  \
  __bktpp = &head->bkts[__bkt];                                               \
  while ((__bktp = *__bktpp))                                                 \
    {                                                                         \
      if (!(cmp)(elm, __bktp))                                                \
        return __bktp;                                                        \
      else                                                                    \
        __bktpp = &__bktp->next;                                              \
    }                                                                         \
                                                                              \
  return NULL;                                                                \
}                                                                             \
                                                                              \
struct type *                                                                 \
name##_HTABLE_FIRST_FROM(struct name *head, int bkt)                          \
{                                                                             \
  struct type *__bktp;                                                        \
                                                                              \
  while (bkt < HTABLE_SIZE(head))                                             \
    {                                                                         \
      if ((__bktp = head->bkts[bkt]))                                         \
        return __bktp;                                                        \
      else                                                                    \
        bkt++;                                                                \
    }                                                                         \
                                                                              \
  return NULL;                                                                \
}                                                                             \
                                                                              \
struct type *                                                                 \
name##_HTABLE_NEXT(struct name *head, struct type *elm)                       \
{                                                                             \
  struct type *__elmp, *__bktp, **__bktpp;                                    \
  uint32_t __bkt;                                                             \
                                                                              \
  __elmp = NULL;                                                              \
  __bkt = name##_HTABLE_FIND_BKT(head, elm);                                  \
  __bktpp = &head->bkts[__bkt];                                               \
  while ((__bktp = *__bktpp))                                                 \
    {                                                                         \
      if (!(cmp)(elm, __bktp))                                                \
        {                                                                     \
          __elmp = __bktp;                                                    \
          break;                                                              \
        }                                                                     \
      else                                                                    \
        __bktpp = &__bktp->next;                                              \
    }                                                                         \
                                                                              \
  if (!__elmp)                                                                \
    return NULL;                                                              \
  else if (__elmp->next)                                                      \
    return __elmp->next;                                                      \
  else                                                                        \
    return name##_HTABLE_FIRST_FROM(head, ++__bkt);                           \
}

#define FIRST_BKT  0

#define HTABLE_INSERT(name, x, y)       name##_HTABLE_INSERT(x, y)
#define HTABLE_REMOVE(name, x, y)       name##_HTABLE_REMOVE(x, y)
#define HTABLE_LOOKUP(name, x, y)       name##_HTABLE_LOOKUP(x, y)
#define HTABLE_FIRST_FROM(name, x, y)   (HTABLE_EMPTY(x) ? NULL               \
                                         : name##_HTABLE_FIRST_FROM(x, y))
#define HTABLE_FIRST(name, x)           HTABLE_FIRST_FROM(name, x, FIRST_BKT)
#define HTABLE_NEXT(name, x, y)         (HTABLE_EMPTY(x) ? NULL               \
                                         : name##_HTABLE_NEXT(x, y))

#define HTABLE_FOREACH(x, name, head)                                         \
  for ((x) = HTABLE_FIRST(name, head);                                        \
       (x) != NULL;                                                           \
       (x) = HTABLE_NEXT(name, head, x))

/*
 * Hash functions.
 */
#ifdef HASH_FUNCTION
#define HTABLE_HASH HASH_FUNCTION
#else
#define HTABLE_HASH HASH_JEN
#endif

#define HASH_JEN_MIX(a, b, c) do {                                            \
  a -= b; a -= c; a ^= (c >> 13);                                             \
  b -= c; b -= a; b ^= (a << 8);                                              \
  c -= a; c -= b; c ^= (b >> 13);                                             \
  a -= b; a -= c; a ^= (c >> 12);                                             \
  b -= c; b -= a; b ^= (a << 16);                                             \
  c -= a; c -= b; c ^= (b >> 5);                                              \
  a -= b; a -= c; a ^= (c >> 3);                                              \
  b -= c; b -= a; b ^= (a << 10);                                             \
  c -= a; c -= b; c ^= (b >> 15);                                             \
} while (0)

#define HASH_JEN(key, keylen, num_bkts, bkt) do {                             \
  register uint32_t i, j, k, hash;                                            \
                                                                              \
  hash = 0xfeedbeef;                                                          \
  i = j = 0x9e3779b9;                                                         \
  k = keylen;                                                                 \
  while (k >= 12)                                                             \
    {                                                                         \
      i += (key[0] + ((unsigned)key[1] << 8)                                  \
            + ((unsigned)key[2] << 16)                                        \
            + ((unsigned)key[3] << 24));                                      \
      j += (key[4] + ((unsigned)key[5] << 8)                                  \
            + ((unsigned)key[6] << 16)                                        \
            + ((unsigned)key[7] << 24 ));                                     \
      hash += (key[8] + ((unsigned)key[9] << 8)                               \
               + ((unsigned)key[10] << 16)                                    \
               + ((unsigned)key[11] << 24));                                  \
                                                                              \
      HASH_JEN_MIX (i, j, hash);                                              \
                                                                              \
      key += 12;                                                              \
      k -= 12;                                                                \
    }                                                                         \
  hash += keylen;                                                             \
  switch (k)                                                                  \
    {                                                                         \
    case 11:                                                                  \
      hash += ((unsigned)key[10] << 24);                                      \
    case 10:                                                                  \
      hash += ((unsigned)key[9] << 16);                                       \
    case 9:                                                                   \
      hash += ((unsigned)key[8] << 8);                                        \
    case 8:                                                                   \
      j += ((unsigned)key[7] << 24);                                          \
    case 7:                                                                   \
      j += ((unsigned)key[6] << 16);                                          \
    case 6:                                                                   \
      j += ((unsigned)key[5] << 8);                                           \
    case 5:                                                                   \
      j += key[4];                                                            \
    case 4:                                                                   \
      i += ((unsigned)key[3] << 24);                                          \
    case 3:                                                                   \
      i += ((unsigned)key[2] << 16);                                          \
    case 2:                                                                   \
      i += ((unsigned)key[1] << 8);                                           \
    case 1:                                                                   \
      i += key[0];                                                            \
    }                                                                         \
  HASH_JEN_MIX (i, j, hash);                                                  \
  bkt = hash % (num_bkts);                                                    \
} while (0)

#define HASH_OAT(key, keylen, num_bkts, bkt) do {                             \
  register uint32_t hash;                                                     \
  int i;                                                                      \
                                                                              \
  hash = 0;                                                                   \
  for (i = 0; i < keylen; i++)                                                \
    {                                                                         \
      hash += key[i];                                                         \
      hash += (hash << 10);                                                   \
      hash ^= (hash >> 6);                                                    \
    }                                                                         \
  hash += (hash << 3);                                                        \
  hash ^= (hash >> 11);                                                       \
  hash += (hash << 15);                                                       \
  bkt = hash % (num_bkts);                                                    \
} while (0)

#endif /* !HTABLE_H */