xref: /freebsd/contrib/elftoolchain/common/uthash.h (revision e0c4386e7e71d93b0edc0c8fa156263fc4a8b0b6)
1 /*
2 Copyright (c) 2003-2013, Troy D. Hanson     http://uthash.sourceforge.net
3 All rights reserved.
4 
5 Redistribution and use in source and binary forms, with or without
6 modification, are permitted provided that the following conditions are met:
7 
8     * Redistributions of source code must retain the above copyright
9       notice, this list of conditions and the following disclaimer.
10 
11 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
12 IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
13 TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
14 PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
15 OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
16 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
17 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
18 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
19 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
20 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
21 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
22 */
23 
24 /* $Id: uthash.h 2682 2012-11-23 22:04:22Z kaiwang27 $ */
25 
26 #ifndef UTHASH_H
27 #define UTHASH_H
28 
29 #include <string.h>   /* memcmp,strlen */
30 #include <stddef.h>   /* ptrdiff_t */
31 #include <stdlib.h>   /* exit() */
32 
33 /* These macros use decltype or the earlier __typeof GNU extension.
34    As decltype is only available in newer compilers (VS2010 or gcc 4.3+
35    when compiling c++ source) this code uses whatever method is needed
36    or, for VS2008 where neither is available, uses casting workarounds. */
37 #ifdef _MSC_VER         /* MS compiler */
38 #if _MSC_VER >= 1600 && defined(__cplusplus)  /* VS2010 or newer in C++ mode */
39 #define DECLTYPE(x) (decltype(x))
40 #else                   /* VS2008 or older (or VS2010 in C mode) */
41 #define NO_DECLTYPE
42 #define DECLTYPE(x)
43 #endif
44 #else                   /* GNU, Sun and other compilers */
45 #define DECLTYPE(x) (__typeof(x))
46 #endif
47 
48 #ifdef NO_DECLTYPE
49 #define DECLTYPE_ASSIGN(dst,src)                                                 \
50 do {                                                                             \
51   char **_da_dst = (char**)(&(dst));                                             \
52   *_da_dst = (char*)(src);                                                       \
53 } while(0)
54 #else
55 #define DECLTYPE_ASSIGN(dst,src)                                                 \
56 do {                                                                             \
57   (dst) = DECLTYPE(dst)(src);                                                    \
58 } while(0)
59 #endif
60 
61 /* a number of the hash function use uint32_t which isn't defined on win32 */
62 #ifdef _MSC_VER
63 typedef unsigned int uint32_t;
64 typedef unsigned char uint8_t;
65 #else
66 #include <inttypes.h>   /* uint32_t */
67 #endif
68 
69 #define UTHASH_VERSION 1.9.7
70 
71 #ifndef uthash_fatal
72 #define uthash_fatal(msg) exit(-1)        /* fatal error (out of memory,etc) */
73 #endif
74 #ifndef uthash_malloc
75 #define uthash_malloc(sz) malloc(sz)      /* malloc fcn                      */
76 #endif
77 #ifndef uthash_free
78 #define uthash_free(ptr,sz) free(ptr)     /* free fcn                        */
79 #endif
80 
81 #ifndef uthash_noexpand_fyi
82 #define uthash_noexpand_fyi(tbl)          /* can be defined to log noexpand  */
83 #endif
84 #ifndef uthash_expand_fyi
85 #define uthash_expand_fyi(tbl)            /* can be defined to log expands   */
86 #endif
87 
88 /* initial number of buckets */
89 #define HASH_INITIAL_NUM_BUCKETS 32      /* initial number of buckets        */
90 #define HASH_INITIAL_NUM_BUCKETS_LOG2 5  /* lg2 of initial number of buckets */
91 #define HASH_BKT_CAPACITY_THRESH 10      /* expand when bucket count reaches */
92 
93 /* calculate the element whose hash handle address is hhe */
94 #define ELMT_FROM_HH(tbl,hhp) ((void*)(((char*)(hhp)) - ((tbl)->hho)))
95 
96 #define HASH_FIND(hh,head,keyptr,keylen,out)                                     \
97 do {                                                                             \
98   unsigned _hf_bkt,_hf_hashv;                                                    \
99   out=NULL;                                                                      \
100   if (head) {                                                                    \
101      HASH_FCN(keyptr,keylen, (head)->hh.tbl->num_buckets, _hf_hashv, _hf_bkt);   \
102      if (HASH_BLOOM_TEST((head)->hh.tbl, _hf_hashv)) {                           \
103        HASH_FIND_IN_BKT((head)->hh.tbl, hh, (head)->hh.tbl->buckets[ _hf_bkt ],  \
104                         keyptr,keylen,out);                                      \
105      }                                                                           \
106   }                                                                              \
107 } while (0)
108 
109 #ifdef HASH_BLOOM
110 #define HASH_BLOOM_BITLEN (1ULL << HASH_BLOOM)
111 #define HASH_BLOOM_BYTELEN (HASH_BLOOM_BITLEN/8) + ((HASH_BLOOM_BITLEN%8) ? 1:0)
112 #define HASH_BLOOM_MAKE(tbl)                                                     \
113 do {                                                                             \
114   (tbl)->bloom_nbits = HASH_BLOOM;                                               \
115   (tbl)->bloom_bv = (uint8_t*)uthash_malloc(HASH_BLOOM_BYTELEN);                 \
116   if (!((tbl)->bloom_bv))  { uthash_fatal( "out of memory"); }                   \
117   memset((tbl)->bloom_bv, 0, HASH_BLOOM_BYTELEN);                                \
118   (tbl)->bloom_sig = HASH_BLOOM_SIGNATURE;                                       \
119 } while (0)
120 
121 #define HASH_BLOOM_FREE(tbl)                                                     \
122 do {                                                                             \
123   uthash_free((tbl)->bloom_bv, HASH_BLOOM_BYTELEN);                              \
124 } while (0)
125 
126 #define HASH_BLOOM_BITSET(bv,idx) (bv[(idx)/8] |= (1U << ((idx)%8)))
127 #define HASH_BLOOM_BITTEST(bv,idx) (bv[(idx)/8] & (1U << ((idx)%8)))
128 
129 #define HASH_BLOOM_ADD(tbl,hashv)                                                \
130   HASH_BLOOM_BITSET((tbl)->bloom_bv, (hashv & (uint32_t)((1ULL << (tbl)->bloom_nbits) - 1)))
131 
132 #define HASH_BLOOM_TEST(tbl,hashv)                                               \
133   HASH_BLOOM_BITTEST((tbl)->bloom_bv, (hashv & (uint32_t)((1ULL << (tbl)->bloom_nbits) - 1)))
134 
135 #else
136 #define HASH_BLOOM_MAKE(tbl)
137 #define HASH_BLOOM_FREE(tbl)
138 #define HASH_BLOOM_ADD(tbl,hashv)
139 #define HASH_BLOOM_TEST(tbl,hashv) (1)
140 #endif
141 
142 #define HASH_MAKE_TABLE(hh,head)                                                 \
143 do {                                                                             \
144   (head)->hh.tbl = (UT_hash_table*)uthash_malloc(                                \
145                   sizeof(UT_hash_table));                                        \
146   if (!((head)->hh.tbl))  { uthash_fatal( "out of memory"); }                    \
147   memset((head)->hh.tbl, 0, sizeof(UT_hash_table));                              \
148   (head)->hh.tbl->tail = &((head)->hh);                                          \
149   (head)->hh.tbl->num_buckets = HASH_INITIAL_NUM_BUCKETS;                        \
150   (head)->hh.tbl->log2_num_buckets = HASH_INITIAL_NUM_BUCKETS_LOG2;              \
151   (head)->hh.tbl->hho = (char*)(&(head)->hh) - (char*)(head);                    \
152   (head)->hh.tbl->buckets = (UT_hash_bucket*)uthash_malloc(                      \
153           HASH_INITIAL_NUM_BUCKETS*sizeof(struct UT_hash_bucket));               \
154   if (! (head)->hh.tbl->buckets) { uthash_fatal( "out of memory"); }             \
155   memset((head)->hh.tbl->buckets, 0,                                             \
156           HASH_INITIAL_NUM_BUCKETS*sizeof(struct UT_hash_bucket));               \
157   HASH_BLOOM_MAKE((head)->hh.tbl);                                               \
158   (head)->hh.tbl->signature = HASH_SIGNATURE;                                    \
159 } while(0)
160 
161 #define HASH_ADD(hh,head,fieldname,keylen_in,add)                                \
162         HASH_ADD_KEYPTR(hh,head,&((add)->fieldname),keylen_in,add)
163 
164 #define HASH_ADD_KEYPTR(hh,head,keyptr,keylen_in,add)                            \
165 do {                                                                             \
166  unsigned _ha_bkt;                                                               \
167  (add)->hh.next = NULL;                                                          \
168  (add)->hh.key = (char*)keyptr;                                                  \
169  (add)->hh.keylen = (unsigned)keylen_in;                                                   \
170  if (!(head)) {                                                                  \
171     head = (add);                                                                \
172     (head)->hh.prev = NULL;                                                      \
173     HASH_MAKE_TABLE(hh,head);                                                    \
174  } else {                                                                        \
175     (head)->hh.tbl->tail->next = (add);                                          \
176     (add)->hh.prev = ELMT_FROM_HH((head)->hh.tbl, (head)->hh.tbl->tail);         \
177     (head)->hh.tbl->tail = &((add)->hh);                                         \
178  }                                                                               \
179  (head)->hh.tbl->num_items++;                                                    \
180  (add)->hh.tbl = (head)->hh.tbl;                                                 \
181  HASH_FCN(keyptr,keylen_in, (head)->hh.tbl->num_buckets,                         \
182          (add)->hh.hashv, _ha_bkt);                                              \
183  HASH_ADD_TO_BKT((head)->hh.tbl->buckets[_ha_bkt],&(add)->hh);                   \
184  HASH_BLOOM_ADD((head)->hh.tbl,(add)->hh.hashv);                                 \
185  HASH_EMIT_KEY(hh,head,keyptr,keylen_in);                                        \
186  HASH_FSCK(hh,head);                                                             \
187 } while(0)
188 
189 #define HASH_TO_BKT( hashv, num_bkts, bkt )                                      \
190 do {                                                                             \
191   bkt = ((hashv) & ((num_bkts) - 1));                                            \
192 } while(0)
193 
194 /* delete "delptr" from the hash table.
195  * "the usual" patch-up process for the app-order doubly-linked-list.
196  * The use of _hd_hh_del below deserves special explanation.
197  * These used to be expressed using (delptr) but that led to a bug
198  * if someone used the same symbol for the head and deletee, like
199  *  HASH_DELETE(hh,users,users);
200  * We want that to work, but by changing the head (users) below
201  * we were forfeiting our ability to further refer to the deletee (users)
202  * in the patch-up process. Solution: use scratch space to
203  * copy the deletee pointer, then the latter references are via that
204  * scratch pointer rather than through the repointed (users) symbol.
205  */
206 #define HASH_DELETE(hh,head,delptr)                                              \
207 do {                                                                             \
208     unsigned _hd_bkt;                                                            \
209     struct UT_hash_handle *_hd_hh_del;                                           \
210     if ( ((delptr)->hh.prev == NULL) && ((delptr)->hh.next == NULL) )  {         \
211         uthash_free((head)->hh.tbl->buckets,                                     \
212                     (head)->hh.tbl->num_buckets*sizeof(struct UT_hash_bucket) ); \
213         HASH_BLOOM_FREE((head)->hh.tbl);                                         \
214         uthash_free((head)->hh.tbl, sizeof(UT_hash_table));                      \
215         head = NULL;                                                             \
216     } else {                                                                     \
217         _hd_hh_del = &((delptr)->hh);                                            \
218         if ((delptr) == ELMT_FROM_HH((head)->hh.tbl,(head)->hh.tbl->tail)) {     \
219             (head)->hh.tbl->tail =                                               \
220                 (UT_hash_handle*)((ptrdiff_t)((delptr)->hh.prev) +               \
221                 (head)->hh.tbl->hho);                                            \
222         }                                                                        \
223         if ((delptr)->hh.prev) {                                                 \
224             ((UT_hash_handle*)((ptrdiff_t)((delptr)->hh.prev) +                  \
225                     (head)->hh.tbl->hho))->next = (delptr)->hh.next;             \
226         } else {                                                                 \
227             DECLTYPE_ASSIGN(head,(delptr)->hh.next);                             \
228         }                                                                        \
229         if (_hd_hh_del->next) {                                                  \
230             ((UT_hash_handle*)((ptrdiff_t)_hd_hh_del->next +                     \
231                     (head)->hh.tbl->hho))->prev =                                \
232                     _hd_hh_del->prev;                                            \
233         }                                                                        \
234         HASH_TO_BKT( _hd_hh_del->hashv, (head)->hh.tbl->num_buckets, _hd_bkt);   \
235         HASH_DEL_IN_BKT(hh,(head)->hh.tbl->buckets[_hd_bkt], _hd_hh_del);        \
236         (head)->hh.tbl->num_items--;                                             \
237     }                                                                            \
238     HASH_FSCK(hh,head);                                                          \
239 } while (0)
240 
241 
242 /* convenience forms of HASH_FIND/HASH_ADD/HASH_DEL */
243 #define HASH_FIND_STR(head,findstr,out)                                          \
244     HASH_FIND(hh,head,findstr,strlen(findstr),out)
245 #define HASH_ADD_STR(head,strfield,add)                                          \
246     HASH_ADD(hh,head,strfield,strlen(add->strfield),add)
247 #define HASH_FIND_INT(head,findint,out)                                          \
248     HASH_FIND(hh,head,findint,sizeof(int),out)
249 #define HASH_ADD_INT(head,intfield,add)                                          \
250     HASH_ADD(hh,head,intfield,sizeof(int),add)
251 #define HASH_FIND_PTR(head,findptr,out)                                          \
252     HASH_FIND(hh,head,findptr,sizeof(void *),out)
253 #define HASH_ADD_PTR(head,ptrfield,add)                                          \
254     HASH_ADD(hh,head,ptrfield,sizeof(void *),add)
255 #define HASH_DEL(head,delptr)                                                    \
256     HASH_DELETE(hh,head,delptr)
257 
258 /* HASH_FSCK checks hash integrity on every add/delete when HASH_DEBUG is defined.
259  * This is for uthash developer only; it compiles away if HASH_DEBUG isn't defined.
260  */
261 #ifdef HASH_DEBUG
262 #define HASH_OOPS(...) do { fprintf(stderr,__VA_ARGS__); exit(-1); } while (0)
263 #define HASH_FSCK(hh,head)                                                       \
264 do {                                                                             \
265     unsigned _bkt_i;                                                             \
266     unsigned _count, _bkt_count;                                                 \
267     char *_prev;                                                                 \
268     struct UT_hash_handle *_thh;                                                 \
269     if (head) {                                                                  \
270         _count = 0;                                                              \
271         for( _bkt_i = 0; _bkt_i < (head)->hh.tbl->num_buckets; _bkt_i++) {       \
272             _bkt_count = 0;                                                      \
273             _thh = (head)->hh.tbl->buckets[_bkt_i].hh_head;                      \
274             _prev = NULL;                                                        \
275             while (_thh) {                                                       \
276                if (_prev != (char*)(_thh->hh_prev)) {                            \
277                    HASH_OOPS("invalid hh_prev %p, actual %p\n",                  \
278                     _thh->hh_prev, _prev );                                      \
279                }                                                                 \
280                _bkt_count++;                                                     \
281                _prev = (char*)(_thh);                                            \
282                _thh = _thh->hh_next;                                             \
283             }                                                                    \
284             _count += _bkt_count;                                                \
285             if ((head)->hh.tbl->buckets[_bkt_i].count !=  _bkt_count) {          \
286                HASH_OOPS("invalid bucket count %d, actual %d\n",                 \
287                 (head)->hh.tbl->buckets[_bkt_i].count, _bkt_count);              \
288             }                                                                    \
289         }                                                                        \
290         if (_count != (head)->hh.tbl->num_items) {                               \
291             HASH_OOPS("invalid hh item count %d, actual %d\n",                   \
292                 (head)->hh.tbl->num_items, _count );                             \
293         }                                                                        \
294         /* traverse hh in app order; check next/prev integrity, count */         \
295         _count = 0;                                                              \
296         _prev = NULL;                                                            \
297         _thh =  &(head)->hh;                                                     \
298         while (_thh) {                                                           \
299            _count++;                                                             \
300            if (_prev !=(char*)(_thh->prev)) {                                    \
301               HASH_OOPS("invalid prev %p, actual %p\n",                          \
302                     _thh->prev, _prev );                                         \
303            }                                                                     \
304            _prev = (char*)ELMT_FROM_HH((head)->hh.tbl, _thh);                    \
305            _thh = ( _thh->next ?  (UT_hash_handle*)((char*)(_thh->next) +        \
306                                   (head)->hh.tbl->hho) : NULL );                 \
307         }                                                                        \
308         if (_count != (head)->hh.tbl->num_items) {                               \
309             HASH_OOPS("invalid app item count %d, actual %d\n",                  \
310                 (head)->hh.tbl->num_items, _count );                             \
311         }                                                                        \
312     }                                                                            \
313 } while (0)
314 #else
315 #define HASH_FSCK(hh,head)
316 #endif
317 
318 /* When compiled with -DHASH_EMIT_KEYS, length-prefixed keys are emitted to
319  * the descriptor to which this macro is defined for tuning the hash function.
320  * The app can #include <unistd.h> to get the prototype for write(2). */
321 #ifdef HASH_EMIT_KEYS
322 #define HASH_EMIT_KEY(hh,head,keyptr,fieldlen)                                   \
323 do {                                                                             \
324     unsigned _klen = fieldlen;                                                   \
325     write(HASH_EMIT_KEYS, &_klen, sizeof(_klen));                                \
326     write(HASH_EMIT_KEYS, keyptr, fieldlen);                                     \
327 } while (0)
328 #else
329 #define HASH_EMIT_KEY(hh,head,keyptr,fieldlen)
330 #endif
331 
332 /* default to Jenkin's hash unless overridden e.g. DHASH_FUNCTION=HASH_SAX */
333 #ifdef HASH_FUNCTION
334 #define HASH_FCN HASH_FUNCTION
335 #else
336 #define HASH_FCN HASH_JEN
337 #endif
338 
339 /* The Bernstein hash function, used in Perl prior to v5.6 */
340 #define HASH_BER(key,keylen,num_bkts,hashv,bkt)                                  \
341 do {                                                                             \
342   unsigned _hb_keylen=keylen;                                                    \
343   char *_hb_key=(char*)(key);                                                    \
344   (hashv) = 0;                                                                   \
345   while (_hb_keylen--)  { (hashv) = ((hashv) * 33) + *_hb_key++; }               \
346   bkt = (hashv) & (num_bkts-1);                                                  \
347 } while (0)
348 
349 
350 /* SAX/FNV/OAT/JEN hash functions are macro variants of those listed at
351  * http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx */
352 #define HASH_SAX(key,keylen,num_bkts,hashv,bkt)                                  \
353 do {                                                                             \
354   unsigned _sx_i;                                                                \
355   char *_hs_key=(char*)(key);                                                    \
356   hashv = 0;                                                                     \
357   for(_sx_i=0; _sx_i < keylen; _sx_i++)                                          \
358       hashv ^= (hashv << 5) + (hashv >> 2) + _hs_key[_sx_i];                     \
359   bkt = hashv & (num_bkts-1);                                                    \
360 } while (0)
361 
362 #define HASH_FNV(key,keylen,num_bkts,hashv,bkt)                                  \
363 do {                                                                             \
364   unsigned _fn_i;                                                                \
365   char *_hf_key=(char*)(key);                                                    \
366   hashv = 2166136261UL;                                                          \
367   for(_fn_i=0; _fn_i < keylen; _fn_i++)                                          \
368       hashv = (hashv * 16777619) ^ _hf_key[_fn_i];                               \
369   bkt = hashv & (num_bkts-1);                                                    \
370 } while(0)
371 
372 #define HASH_OAT(key,keylen,num_bkts,hashv,bkt)                                  \
373 do {                                                                             \
374   unsigned _ho_i;                                                                \
375   char *_ho_key=(char*)(key);                                                    \
376   hashv = 0;                                                                     \
377   for(_ho_i=0; _ho_i < keylen; _ho_i++) {                                        \
378       hashv += _ho_key[_ho_i];                                                   \
379       hashv += (hashv << 10);                                                    \
380       hashv ^= (hashv >> 6);                                                     \
381   }                                                                              \
382   hashv += (hashv << 3);                                                         \
383   hashv ^= (hashv >> 11);                                                        \
384   hashv += (hashv << 15);                                                        \
385   bkt = hashv & (num_bkts-1);                                                    \
386 } while(0)
387 
388 #define HASH_JEN_MIX(a,b,c)                                                      \
389 do {                                                                             \
390   a -= b; a -= c; a ^= ( c >> 13 );                                              \
391   b -= c; b -= a; b ^= ( a << 8 );                                               \
392   c -= a; c -= b; c ^= ( b >> 13 );                                              \
393   a -= b; a -= c; a ^= ( c >> 12 );                                              \
394   b -= c; b -= a; b ^= ( a << 16 );                                              \
395   c -= a; c -= b; c ^= ( b >> 5 );                                               \
396   a -= b; a -= c; a ^= ( c >> 3 );                                               \
397   b -= c; b -= a; b ^= ( a << 10 );                                              \
398   c -= a; c -= b; c ^= ( b >> 15 );                                              \
399 } while (0)
400 
401 #define HASH_JEN(key,keylen,num_bkts,hashv,bkt)                                  \
402 do {                                                                             \
403   unsigned _hj_i,_hj_j,_hj_k;                                                    \
404   char *_hj_key=(char*)(key);                                                    \
405   hashv = 0xfeedbeef;                                                            \
406   _hj_i = _hj_j = 0x9e3779b9;                                                    \
407   _hj_k = (unsigned)keylen;                                                                \
408   while (_hj_k >= 12) {                                                          \
409     _hj_i +=    (_hj_key[0] + ( (unsigned)_hj_key[1] << 8 )                      \
410         + ( (unsigned)_hj_key[2] << 16 )                                         \
411         + ( (unsigned)_hj_key[3] << 24 ) );                                      \
412     _hj_j +=    (_hj_key[4] + ( (unsigned)_hj_key[5] << 8 )                      \
413         + ( (unsigned)_hj_key[6] << 16 )                                         \
414         + ( (unsigned)_hj_key[7] << 24 ) );                                      \
415     hashv += (_hj_key[8] + ( (unsigned)_hj_key[9] << 8 )                         \
416         + ( (unsigned)_hj_key[10] << 16 )                                        \
417         + ( (unsigned)_hj_key[11] << 24 ) );                                     \
418                                                                                  \
419      HASH_JEN_MIX(_hj_i, _hj_j, hashv);                                          \
420                                                                                  \
421      _hj_key += 12;                                                              \
422      _hj_k -= 12;                                                                \
423   }                                                                              \
424   hashv += keylen;                                                               \
425   switch ( _hj_k ) {                                                             \
426      case 11: hashv += ( (unsigned)_hj_key[10] << 24 );                          \
427      case 10: hashv += ( (unsigned)_hj_key[9] << 16 );                           \
428      case 9:  hashv += ( (unsigned)_hj_key[8] << 8 );                            \
429      case 8:  _hj_j += ( (unsigned)_hj_key[7] << 24 );                           \
430      case 7:  _hj_j += ( (unsigned)_hj_key[6] << 16 );                           \
431      case 6:  _hj_j += ( (unsigned)_hj_key[5] << 8 );                            \
432      case 5:  _hj_j += _hj_key[4];                                               \
433      case 4:  _hj_i += ( (unsigned)_hj_key[3] << 24 );                           \
434      case 3:  _hj_i += ( (unsigned)_hj_key[2] << 16 );                           \
435      case 2:  _hj_i += ( (unsigned)_hj_key[1] << 8 );                            \
436      case 1:  _hj_i += _hj_key[0];                                               \
437   }                                                                              \
438   HASH_JEN_MIX(_hj_i, _hj_j, hashv);                                             \
439   bkt = hashv & (num_bkts-1);                                                    \
440 } while(0)
441 
442 /* The Paul Hsieh hash function */
443 #undef get16bits
444 #if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__)             \
445   || defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
446 #define get16bits(d) (*((const uint16_t *) (d)))
447 #endif
448 
449 #if !defined (get16bits)
450 #define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)             \
451                        +(uint32_t)(((const uint8_t *)(d))[0]) )
452 #endif
453 #define HASH_SFH(key,keylen,num_bkts,hashv,bkt)                                  \
454 do {                                                                             \
455   char *_sfh_key=(char*)(key);                                                   \
456   uint32_t _sfh_tmp, _sfh_len = keylen;                                          \
457                                                                                  \
458   int _sfh_rem = _sfh_len & 3;                                                   \
459   _sfh_len >>= 2;                                                                \
460   hashv = 0xcafebabe;                                                            \
461                                                                                  \
462   /* Main loop */                                                                \
463   for (;_sfh_len > 0; _sfh_len--) {                                              \
464     hashv    += get16bits (_sfh_key);                                            \
465     _sfh_tmp       = (get16bits (_sfh_key+2) << 11) ^ hashv;                     \
466     hashv     = (hashv << 16) ^ _sfh_tmp;                                        \
467     _sfh_key += 2*sizeof (uint16_t);                                             \
468     hashv    += hashv >> 11;                                                     \
469   }                                                                              \
470                                                                                  \
471   /* Handle end cases */                                                         \
472   switch (_sfh_rem) {                                                            \
473     case 3: hashv += get16bits (_sfh_key);                                       \
474             hashv ^= hashv << 16;                                                \
475             hashv ^= _sfh_key[sizeof (uint16_t)] << 18;                          \
476             hashv += hashv >> 11;                                                \
477             break;                                                               \
478     case 2: hashv += get16bits (_sfh_key);                                       \
479             hashv ^= hashv << 11;                                                \
480             hashv += hashv >> 17;                                                \
481             break;                                                               \
482     case 1: hashv += *_sfh_key;                                                  \
483             hashv ^= hashv << 10;                                                \
484             hashv += hashv >> 1;                                                 \
485   }                                                                              \
486                                                                                  \
487     /* Force "avalanching" of final 127 bits */                                  \
488     hashv ^= hashv << 3;                                                         \
489     hashv += hashv >> 5;                                                         \
490     hashv ^= hashv << 4;                                                         \
491     hashv += hashv >> 17;                                                        \
492     hashv ^= hashv << 25;                                                        \
493     hashv += hashv >> 6;                                                         \
494     bkt = hashv & (num_bkts-1);                                                  \
495 } while(0)
496 
497 #ifdef HASH_USING_NO_STRICT_ALIASING
498 /* The MurmurHash exploits some CPU's (x86,x86_64) tolerance for unaligned reads.
499  * For other types of CPU's (e.g. Sparc) an unaligned read causes a bus error.
500  * MurmurHash uses the faster approach only on CPU's where we know it's safe.
501  *
502  * Note the preprocessor built-in defines can be emitted using:
503  *
504  *   gcc -m64 -dM -E - < /dev/null                  (on gcc)
505  *   cc -## a.c (where a.c is a simple test file)   (Sun Studio)
506  */
507 #if (defined(__i386__) || defined(__x86_64__)  || defined(_M_IX86))
508 #define MUR_GETBLOCK(p,i) p[i]
509 #else /* non intel */
510 #define MUR_PLUS0_ALIGNED(p) (((unsigned long)p & 0x3) == 0)
511 #define MUR_PLUS1_ALIGNED(p) (((unsigned long)p & 0x3) == 1)
512 #define MUR_PLUS2_ALIGNED(p) (((unsigned long)p & 0x3) == 2)
513 #define MUR_PLUS3_ALIGNED(p) (((unsigned long)p & 0x3) == 3)
514 #define WP(p) ((uint32_t*)((unsigned long)(p) & ~3UL))
515 #if (defined(__BIG_ENDIAN__) || defined(SPARC) || defined(__ppc__) || defined(__ppc64__))
516 #define MUR_THREE_ONE(p) ((((*WP(p))&0x00ffffff) << 8) | (((*(WP(p)+1))&0xff000000) >> 24))
517 #define MUR_TWO_TWO(p)   ((((*WP(p))&0x0000ffff) <<16) | (((*(WP(p)+1))&0xffff0000) >> 16))
518 #define MUR_ONE_THREE(p) ((((*WP(p))&0x000000ff) <<24) | (((*(WP(p)+1))&0xffffff00) >>  8))
519 #else /* assume little endian non-intel */
520 #define MUR_THREE_ONE(p) ((((*WP(p))&0xffffff00) >> 8) | (((*(WP(p)+1))&0x000000ff) << 24))
521 #define MUR_TWO_TWO(p)   ((((*WP(p))&0xffff0000) >>16) | (((*(WP(p)+1))&0x0000ffff) << 16))
522 #define MUR_ONE_THREE(p) ((((*WP(p))&0xff000000) >>24) | (((*(WP(p)+1))&0x00ffffff) <<  8))
523 #endif
524 #define MUR_GETBLOCK(p,i) (MUR_PLUS0_ALIGNED(p) ? ((p)[i]) :           \
525                             (MUR_PLUS1_ALIGNED(p) ? MUR_THREE_ONE(p) : \
526                              (MUR_PLUS2_ALIGNED(p) ? MUR_TWO_TWO(p) :  \
527                                                       MUR_ONE_THREE(p))))
528 #endif
529 #define MUR_ROTL32(x,r) (((x) << (r)) | ((x) >> (32 - (r))))
530 #define MUR_FMIX(_h) \
531 do {                 \
532   _h ^= _h >> 16;    \
533   _h *= 0x85ebca6b;  \
534   _h ^= _h >> 13;    \
535   _h *= 0xc2b2ae35l; \
536   _h ^= _h >> 16;    \
537 } while(0)
538 
539 #define HASH_MUR(key,keylen,num_bkts,hashv,bkt)                        \
540 do {                                                                   \
541   const uint8_t *_mur_data = (const uint8_t*)(key);                    \
542   const int _mur_nblocks = (keylen) / 4;                               \
543   uint32_t _mur_h1 = 0xf88D5353;                                       \
544   uint32_t _mur_c1 = 0xcc9e2d51;                                       \
545   uint32_t _mur_c2 = 0x1b873593;                                       \
546   uint32_t _mur_k1 = 0;                                                \
547   const uint8_t *_mur_tail;                                            \
548   const uint32_t *_mur_blocks = (const uint32_t*)(_mur_data+_mur_nblocks*4); \
549   int _mur_i;                                                          \
550   for(_mur_i = -_mur_nblocks; _mur_i; _mur_i++) {                      \
551     _mur_k1 = MUR_GETBLOCK(_mur_blocks,_mur_i);                        \
552     _mur_k1 *= _mur_c1;                                                \
553     _mur_k1 = MUR_ROTL32(_mur_k1,15);                                  \
554     _mur_k1 *= _mur_c2;                                                \
555                                                                        \
556     _mur_h1 ^= _mur_k1;                                                \
557     _mur_h1 = MUR_ROTL32(_mur_h1,13);                                  \
558     _mur_h1 = _mur_h1*5+0xe6546b64;                                    \
559   }                                                                    \
560   _mur_tail = (const uint8_t*)(_mur_data + _mur_nblocks*4);            \
561   _mur_k1=0;                                                           \
562   switch((keylen) & 3) {                                               \
563     case 3: _mur_k1 ^= _mur_tail[2] << 16;                             \
564     case 2: _mur_k1 ^= _mur_tail[1] << 8;                              \
565     case 1: _mur_k1 ^= _mur_tail[0];                                   \
566     _mur_k1 *= _mur_c1;                                                \
567     _mur_k1 = MUR_ROTL32(_mur_k1,15);                                  \
568     _mur_k1 *= _mur_c2;                                                \
569     _mur_h1 ^= _mur_k1;                                                \
570   }                                                                    \
571   _mur_h1 ^= (keylen);                                                 \
572   MUR_FMIX(_mur_h1);                                                   \
573   hashv = _mur_h1;                                                     \
574   bkt = hashv & (num_bkts-1);                                          \
575 } while(0)
576 #endif  /* HASH_USING_NO_STRICT_ALIASING */
577 
578 /* key comparison function; return 0 if keys equal */
579 #define HASH_KEYCMP(a,b,len) memcmp(a,b,len)
580 
581 /* iterate over items in a known bucket to find desired item */
582 #define HASH_FIND_IN_BKT(tbl,hh,head,keyptr,keylen_in,out)                       \
583 do {                                                                             \
584  if (head.hh_head) DECLTYPE_ASSIGN(out,ELMT_FROM_HH(tbl,head.hh_head));          \
585  else out=NULL;                                                                  \
586  while (out) {                                                                   \
587     if ((out)->hh.keylen == keylen_in) {                                           \
588         if ((HASH_KEYCMP((out)->hh.key,keyptr,keylen_in)) == 0) break;             \
589     }                                                                            \
590     if ((out)->hh.hh_next) DECLTYPE_ASSIGN(out,ELMT_FROM_HH(tbl,(out)->hh.hh_next)); \
591     else out = NULL;                                                             \
592  }                                                                               \
593 } while(0)
594 
595 /* add an item to a bucket  */
596 #define HASH_ADD_TO_BKT(head,addhh)                                              \
597 do {                                                                             \
598  head.count++;                                                                   \
599  (addhh)->hh_next = head.hh_head;                                                \
600  (addhh)->hh_prev = NULL;                                                        \
601  if (head.hh_head) { (head).hh_head->hh_prev = (addhh); }                        \
602  (head).hh_head=addhh;                                                           \
603  if (head.count >= ((head.expand_mult+1) * HASH_BKT_CAPACITY_THRESH)             \
604      && (addhh)->tbl->noexpand != 1) {                                           \
605        HASH_EXPAND_BUCKETS((addhh)->tbl);                                        \
606  }                                                                               \
607 } while(0)
608 
609 /* remove an item from a given bucket */
610 #define HASH_DEL_IN_BKT(hh,head,hh_del)                                          \
611     (head).count--;                                                              \
612     if ((head).hh_head == hh_del) {                                              \
613       (head).hh_head = hh_del->hh_next;                                          \
614     }                                                                            \
615     if (hh_del->hh_prev) {                                                       \
616         hh_del->hh_prev->hh_next = hh_del->hh_next;                              \
617     }                                                                            \
618     if (hh_del->hh_next) {                                                       \
619         hh_del->hh_next->hh_prev = hh_del->hh_prev;                              \
620     }
621 
622 /* Bucket expansion has the effect of doubling the number of buckets
623  * and redistributing the items into the new buckets. Ideally the
624  * items will distribute more or less evenly into the new buckets
625  * (the extent to which this is true is a measure of the quality of
626  * the hash function as it applies to the key domain).
627  *
628  * With the items distributed into more buckets, the chain length
629  * (item count) in each bucket is reduced. Thus by expanding buckets
630  * the hash keeps a bound on the chain length. This bounded chain
631  * length is the essence of how a hash provides constant time lookup.
632  *
633  * The calculation of tbl->ideal_chain_maxlen below deserves some
634  * explanation. First, keep in mind that we're calculating the ideal
635  * maximum chain length based on the *new* (doubled) bucket count.
636  * In fractions this is just n/b (n=number of items,b=new num buckets).
637  * Since the ideal chain length is an integer, we want to calculate
638  * ceil(n/b). We don't depend on floating point arithmetic in this
639  * hash, so to calculate ceil(n/b) with integers we could write
640  *
641  *      ceil(n/b) = (n/b) + ((n%b)?1:0)
642  *
643  * and in fact a previous version of this hash did just that.
644  * But now we have improved things a bit by recognizing that b is
645  * always a power of two. We keep its base 2 log handy (call it lb),
646  * so now we can write this with a bit shift and logical AND:
647  *
648  *      ceil(n/b) = (n>>lb) + ( (n & (b-1)) ? 1:0)
649  *
650  */
651 #define HASH_EXPAND_BUCKETS(tbl)                                                 \
652 do {                                                                             \
653     unsigned _he_bkt;                                                            \
654     unsigned _he_bkt_i;                                                          \
655     struct UT_hash_handle *_he_thh, *_he_hh_nxt;                                 \
656     UT_hash_bucket *_he_new_buckets, *_he_newbkt;                                \
657     _he_new_buckets = (UT_hash_bucket*)uthash_malloc(                            \
658              2 * tbl->num_buckets * sizeof(struct UT_hash_bucket));              \
659     if (!_he_new_buckets) { uthash_fatal( "out of memory"); }                    \
660     memset(_he_new_buckets, 0,                                                   \
661             2 * tbl->num_buckets * sizeof(struct UT_hash_bucket));               \
662     tbl->ideal_chain_maxlen =                                                    \
663        (tbl->num_items >> (tbl->log2_num_buckets+1)) +                           \
664        ((tbl->num_items & ((tbl->num_buckets*2)-1)) ? 1 : 0);                    \
665     tbl->nonideal_items = 0;                                                     \
666     for(_he_bkt_i = 0; _he_bkt_i < tbl->num_buckets; _he_bkt_i++)                \
667     {                                                                            \
668         _he_thh = tbl->buckets[ _he_bkt_i ].hh_head;                             \
669         while (_he_thh) {                                                        \
670            _he_hh_nxt = _he_thh->hh_next;                                        \
671            HASH_TO_BKT( _he_thh->hashv, tbl->num_buckets*2, _he_bkt);            \
672            _he_newbkt = &(_he_new_buckets[ _he_bkt ]);                           \
673            if (++(_he_newbkt->count) > tbl->ideal_chain_maxlen) {                \
674              tbl->nonideal_items++;                                              \
675              _he_newbkt->expand_mult = _he_newbkt->count /                       \
676                                         tbl->ideal_chain_maxlen;                 \
677            }                                                                     \
678            _he_thh->hh_prev = NULL;                                              \
679            _he_thh->hh_next = _he_newbkt->hh_head;                               \
680            if (_he_newbkt->hh_head) _he_newbkt->hh_head->hh_prev =               \
681                 _he_thh;                                                         \
682            _he_newbkt->hh_head = _he_thh;                                        \
683            _he_thh = _he_hh_nxt;                                                 \
684         }                                                                        \
685     }                                                                            \
686     uthash_free( tbl->buckets, tbl->num_buckets*sizeof(struct UT_hash_bucket) ); \
687     tbl->num_buckets *= 2;                                                       \
688     tbl->log2_num_buckets++;                                                     \
689     tbl->buckets = _he_new_buckets;                                              \
690     tbl->ineff_expands = (tbl->nonideal_items > (tbl->num_items >> 1)) ?         \
691         (tbl->ineff_expands+1) : 0;                                              \
692     if (tbl->ineff_expands > 1) {                                                \
693         tbl->noexpand=1;                                                         \
694         uthash_noexpand_fyi(tbl);                                                \
695     }                                                                            \
696     uthash_expand_fyi(tbl);                                                      \
697 } while(0)
698 
699 
700 /* This is an adaptation of Simon Tatham's O(n log(n)) mergesort */
701 /* Note that HASH_SORT assumes the hash handle name to be hh.
702  * HASH_SRT was added to allow the hash handle name to be passed in. */
703 #define HASH_SORT(head,cmpfcn) HASH_SRT(hh,head,cmpfcn)
704 #define HASH_SRT(hh,head,cmpfcn)                                                 \
705 do {                                                                             \
706   unsigned _hs_i;                                                                \
707   unsigned _hs_looping,_hs_nmerges,_hs_insize,_hs_psize,_hs_qsize;               \
708   struct UT_hash_handle *_hs_p, *_hs_q, *_hs_e, *_hs_list, *_hs_tail;            \
709   if (head) {                                                                    \
710       _hs_insize = 1;                                                            \
711       _hs_looping = 1;                                                           \
712       _hs_list = &((head)->hh);                                                  \
713       while (_hs_looping) {                                                      \
714           _hs_p = _hs_list;                                                      \
715           _hs_list = NULL;                                                       \
716           _hs_tail = NULL;                                                       \
717           _hs_nmerges = 0;                                                       \
718           while (_hs_p) {                                                        \
719               _hs_nmerges++;                                                     \
720               _hs_q = _hs_p;                                                     \
721               _hs_psize = 0;                                                     \
722               for ( _hs_i = 0; _hs_i  < _hs_insize; _hs_i++ ) {                  \
723                   _hs_psize++;                                                   \
724                   _hs_q = (UT_hash_handle*)((_hs_q->next) ?                      \
725                           ((void*)((char*)(_hs_q->next) +                        \
726                           (head)->hh.tbl->hho)) : NULL);                         \
727                   if (! (_hs_q) ) break;                                         \
728               }                                                                  \
729               _hs_qsize = _hs_insize;                                            \
730               while ((_hs_psize > 0) || ((_hs_qsize > 0) && _hs_q )) {           \
731                   if (_hs_psize == 0) {                                          \
732                       _hs_e = _hs_q;                                             \
733                       _hs_q = (UT_hash_handle*)((_hs_q->next) ?                  \
734                               ((void*)((char*)(_hs_q->next) +                    \
735                               (head)->hh.tbl->hho)) : NULL);                     \
736                       _hs_qsize--;                                               \
737                   } else if ( (_hs_qsize == 0) || !(_hs_q) ) {                   \
738                       _hs_e = _hs_p;                                             \
739                       _hs_p = (UT_hash_handle*)((_hs_p->next) ?                  \
740                               ((void*)((char*)(_hs_p->next) +                    \
741                               (head)->hh.tbl->hho)) : NULL);                     \
742                       _hs_psize--;                                               \
743                   } else if ((                                                   \
744                       cmpfcn(DECLTYPE(head)(ELMT_FROM_HH((head)->hh.tbl,_hs_p)), \
745                              DECLTYPE(head)(ELMT_FROM_HH((head)->hh.tbl,_hs_q))) \
746                              ) <= 0) {                                           \
747                       _hs_e = _hs_p;                                             \
748                       _hs_p = (UT_hash_handle*)((_hs_p->next) ?                  \
749                               ((void*)((char*)(_hs_p->next) +                    \
750                               (head)->hh.tbl->hho)) : NULL);                     \
751                       _hs_psize--;                                               \
752                   } else {                                                       \
753                       _hs_e = _hs_q;                                             \
754                       _hs_q = (UT_hash_handle*)((_hs_q->next) ?                  \
755                               ((void*)((char*)(_hs_q->next) +                    \
756                               (head)->hh.tbl->hho)) : NULL);                     \
757                       _hs_qsize--;                                               \
758                   }                                                              \
759                   if ( _hs_tail ) {                                              \
760                       _hs_tail->next = ((_hs_e) ?                                \
761                             ELMT_FROM_HH((head)->hh.tbl,_hs_e) : NULL);          \
762                   } else {                                                       \
763                       _hs_list = _hs_e;                                          \
764                   }                                                              \
765                   _hs_e->prev = ((_hs_tail) ?                                    \
766                      ELMT_FROM_HH((head)->hh.tbl,_hs_tail) : NULL);              \
767                   _hs_tail = _hs_e;                                              \
768               }                                                                  \
769               _hs_p = _hs_q;                                                     \
770           }                                                                      \
771           _hs_tail->next = NULL;                                                 \
772           if ( _hs_nmerges <= 1 ) {                                              \
773               _hs_looping=0;                                                     \
774               (head)->hh.tbl->tail = _hs_tail;                                   \
775               DECLTYPE_ASSIGN(head,ELMT_FROM_HH((head)->hh.tbl, _hs_list));      \
776           }                                                                      \
777           _hs_insize *= 2;                                                       \
778       }                                                                          \
779       HASH_FSCK(hh,head);                                                        \
780  }                                                                               \
781 } while (0)
782 
783 /* This function selects items from one hash into another hash.
784  * The end result is that the selected items have dual presence
785  * in both hashes. There is no copy of the items made; rather
786  * they are added into the new hash through a secondary hash
787  * hash handle that must be present in the structure. */
788 #define HASH_SELECT(hh_dst, dst, hh_src, src, cond)                              \
789 do {                                                                             \
790   unsigned _src_bkt, _dst_bkt;                                                   \
791   void *_last_elt=NULL, *_elt;                                                   \
792   UT_hash_handle *_src_hh, *_dst_hh, *_last_elt_hh=NULL;                         \
793   ptrdiff_t _dst_hho = ((char*)(&(dst)->hh_dst) - (char*)(dst));                 \
794   if (src) {                                                                     \
795     for(_src_bkt=0; _src_bkt < (src)->hh_src.tbl->num_buckets; _src_bkt++) {     \
796       for(_src_hh = (src)->hh_src.tbl->buckets[_src_bkt].hh_head;                \
797           _src_hh;                                                               \
798           _src_hh = _src_hh->hh_next) {                                          \
799           _elt = ELMT_FROM_HH((src)->hh_src.tbl, _src_hh);                       \
800           if (cond(_elt)) {                                                      \
801             _dst_hh = (UT_hash_handle*)(((char*)_elt) + _dst_hho);               \
802             _dst_hh->key = _src_hh->key;                                         \
803             _dst_hh->keylen = _src_hh->keylen;                                   \
804             _dst_hh->hashv = _src_hh->hashv;                                     \
805             _dst_hh->prev = _last_elt;                                           \
806             _dst_hh->next = NULL;                                                \
807             if (_last_elt_hh) { _last_elt_hh->next = _elt; }                     \
808             if (!dst) {                                                          \
809               DECLTYPE_ASSIGN(dst,_elt);                                         \
810               HASH_MAKE_TABLE(hh_dst,dst);                                       \
811             } else {                                                             \
812               _dst_hh->tbl = (dst)->hh_dst.tbl;                                  \
813             }                                                                    \
814             HASH_TO_BKT(_dst_hh->hashv, _dst_hh->tbl->num_buckets, _dst_bkt);    \
815             HASH_ADD_TO_BKT(_dst_hh->tbl->buckets[_dst_bkt],_dst_hh);            \
816             (dst)->hh_dst.tbl->num_items++;                                      \
817             _last_elt = _elt;                                                    \
818             _last_elt_hh = _dst_hh;                                              \
819           }                                                                      \
820       }                                                                          \
821     }                                                                            \
822   }                                                                              \
823   HASH_FSCK(hh_dst,dst);                                                         \
824 } while (0)
825 
826 #define HASH_CLEAR(hh,head)                                                      \
827 do {                                                                             \
828   if (head) {                                                                    \
829     uthash_free((head)->hh.tbl->buckets,                                         \
830                 (head)->hh.tbl->num_buckets*sizeof(struct UT_hash_bucket));      \
831     HASH_BLOOM_FREE((head)->hh.tbl);                                             \
832     uthash_free((head)->hh.tbl, sizeof(UT_hash_table));                          \
833     (head)=NULL;                                                                 \
834   }                                                                              \
835 } while(0)
836 
837 #ifdef NO_DECLTYPE
838 #define HASH_ITER(hh,head,el,tmp)                                                \
839 for((el)=(head), (*(char**)(&(tmp)))=(char*)((head)?(head)->hh.next:NULL);       \
840   el; (el)=(tmp),(*(char**)(&(tmp)))=(char*)((tmp)?(tmp)->hh.next:NULL))
841 #else
842 #define HASH_ITER(hh,head,el,tmp)                                                \
843 for((el)=(head),(tmp)=DECLTYPE(el)((head)?(head)->hh.next:NULL);                 \
844   el; (el)=(tmp),(tmp)=DECLTYPE(el)((tmp)?(tmp)->hh.next:NULL))
845 #endif
846 
847 /* obtain a count of items in the hash */
848 #define HASH_COUNT(head) HASH_CNT(hh,head)
849 #define HASH_CNT(hh,head) ((head)?((head)->hh.tbl->num_items):0)
850 
851 typedef struct UT_hash_bucket {
852    struct UT_hash_handle *hh_head;
853    unsigned count;
854 
855    /* expand_mult is normally set to 0. In this situation, the max chain length
856     * threshold is enforced at its default value, HASH_BKT_CAPACITY_THRESH. (If
857     * the bucket's chain exceeds this length, bucket expansion is triggered).
858     * However, setting expand_mult to a non-zero value delays bucket expansion
859     * (that would be triggered by additions to this particular bucket)
860     * until its chain length reaches a *multiple* of HASH_BKT_CAPACITY_THRESH.
861     * (The multiplier is simply expand_mult+1). The whole idea of this
862     * multiplier is to reduce bucket expansions, since they are expensive, in
863     * situations where we know that a particular bucket tends to be overused.
864     * It is better to let its chain length grow to a longer yet-still-bounded
865     * value, than to do an O(n) bucket expansion too often.
866     */
867    unsigned expand_mult;
868 
869 } UT_hash_bucket;
870 
871 /* random signature used only to find hash tables in external analysis */
872 #define HASH_SIGNATURE 0xa0111fe1
873 #define HASH_BLOOM_SIGNATURE 0xb12220f2
874 
875 typedef struct UT_hash_table {
876    UT_hash_bucket *buckets;
877    unsigned num_buckets, log2_num_buckets;
878    unsigned num_items;
879    struct UT_hash_handle *tail; /* tail hh in app order, for fast append    */
880    ptrdiff_t hho; /* hash handle offset (byte pos of hash handle in element */
881 
882    /* in an ideal situation (all buckets used equally), no bucket would have
883     * more than ceil(#items/#buckets) items. that's the ideal chain length. */
884    unsigned ideal_chain_maxlen;
885 
886    /* nonideal_items is the number of items in the hash whose chain position
887     * exceeds the ideal chain maxlen. these items pay the penalty for an uneven
888     * hash distribution; reaching them in a chain traversal takes >ideal steps */
889    unsigned nonideal_items;
890 
891    /* ineffective expands occur when a bucket doubling was performed, but
892     * afterward, more than half the items in the hash had nonideal chain
893     * positions. If this happens on two consecutive expansions we inhibit any
894     * further expansion, as it's not helping; this happens when the hash
895     * function isn't a good fit for the key domain. When expansion is inhibited
896     * the hash will still work, albeit no longer in constant time. */
897    unsigned ineff_expands, noexpand;
898 
899    uint32_t signature; /* used only to find hash tables in external analysis */
900 #ifdef HASH_BLOOM
901    uint32_t bloom_sig; /* used only to test bloom exists in external analysis */
902    uint8_t *bloom_bv;
903    char bloom_nbits;
904 #endif
905 
906 } UT_hash_table;
907 
908 typedef struct UT_hash_handle {
909    struct UT_hash_table *tbl;
910    void *prev;                       /* prev element in app order      */
911    void *next;                       /* next element in app order      */
912    struct UT_hash_handle *hh_prev;   /* previous hh in bucket order    */
913    struct UT_hash_handle *hh_next;   /* next hh in bucket order        */
914    void *key;                        /* ptr to enclosing struct's key  */
915    unsigned keylen;                  /* enclosing struct's key len     */
916    unsigned hashv;                   /* result of hash-fcn(key)        */
917 } UT_hash_handle;
918 
919 #endif /* UTHASH_H */
920