1 /* Set --- collection of entries that are unique wrt to a key.
2 Copyright (C) 1995, 1996 Markus Armbruster */
4 /* This code is derived from:
6 From: ejp@ausmelb.oz.AU (Esmond Pitt)
7 Date: Tue, 7 Mar 1989 22:06:26 GMT
8 Subject: v06i042: dynamic hashing version of hsearch(3)
9 Message-ID: <1821@basser.oz>
10 Newsgroups: comp.sources.misc
11 Sender: msgs@basser.oz
13 Posting-number: Volume 6, Issue 42
14 Submitted-By: Esmond Pitt <ejp@ausmelb.oz.AU>
15 Archive-name: dynamic-hash
17 * Dynamic hashing, after CACM April 1988 pp 446-457, by Per-Ake Larson.
18 * Coded into C, with minor code improvements, and with hsearch(3) interface,
19 * by ejp@ausmelb.oz, Jul 26, 1988: 13:16;
21 TODO: Fix Esmond's ugly MixedCapsIdentifiers ;->
36 /* bcopy is not ISO C *
37 #define bcopy(X, Y, Z) memcpy((Y), (X), (Z))
42 # define PMANGLE(pre) pre##_pset
43 # define MANGLEP(post) pset_##post
44 # define MANGLE(pre, post) pre##pset##post
45 # define EQUAL(cmp, elt, key, siz) (!(cmp) ((elt)->entry.dptr, (key)))
48 # define PMANGLE(pre) pre##_set
49 # define MANGLEP(post) set_##post
50 # define MANGLE(pre, post) pre##set##post
51 # define EQUAL(cmp, elt, key, siz) \
52 (((elt)->entry.size == (siz)) && !(cmp) ((elt)->entry.dptr, (key), (siz)))
66 #define TOBSTACK_ID MANGLEP(tag)
70 #define SEGMENT_SIZE_SHIFT 8
71 #define SEGMENT_SIZE (1 << SEGMENT_SIZE_SHIFT)
72 #define DIRECTORY_SIZE_SHIFT 8
73 #define DIRECTORY_SIZE (1 << DIRECTORY_SIZE_SHIFT)
74 #define MAX_LOAD_FACTOR 4
77 typedef struct element {
78 struct element *chain;
79 MANGLEP (entry) entry;
84 short p; /* Next bucket to be split */
85 short maxp; /* upper bound on p during expansion */
86 int nkey; /* current # keys */
87 short nseg; /* current # segments */
88 Segment *dir[DIRECTORY_SIZE];
89 MANGLEP(cmp_fun) cmp; /* function comparing entries */
91 Element *iter_tail; /* non-NULL while iterating over elts */
97 int naccess, ncollision, ndups;
109 MANGLEP(stats) (SET *table)
113 Element *q = table->free_list;
114 while (q) { q = q->chain; ++nfree; }
116 printf (" accesses collisions keys duplicates longest wasted\n%12d%12d%12d%12d%12d%12d\n",
117 table->naccess, table->ncollision, table->nkey, table->ndups, table->max_chain_len, nfree);
121 stat_chain_len (SET *table, int chain_len)
123 table->ncollision += chain_len;
124 if (table->max_chain_len < chain_len) table->max_chain_len = chain_len;
127 # define stat_access(table) (++(table)->naccess)
128 # define stat_dup(table) (++(table)->ndups)
132 # define stat_chain_len(table, chain_len) ((void)0)
133 # define stat_access(table) ((void)0)
134 # define stat_dup(table) ((void)0)
140 const char *MANGLEP(tag);
144 MANGLEP(describe) (SET *table)
150 printf ("p=%d maxp=%d nkey=%d nseg=%d\n",
151 table->p, table->maxp, table->nkey, table->nseg);
152 for (i = 0; i < table->nseg; i++) {
154 for (j = 0; j < SEGMENT_SIZE; j++) {
158 if (collide) printf ("<%3d>", collide);
159 else printf ("table");
160 printf ("[%d][%3d]: %u %p\n", i, j, ptr->entry.hash, ptr->entry.dptr);
172 (PMANGLE(new)) (MANGLEP(cmp_fun) cmp, int nslots)
175 SET *table = xmalloc (sizeof (SET));
177 /* Adjust nslots up to next power of 2, minimum SEGMENT_SIZE */
178 assert (nslots >= 0);
179 for (i = SEGMENT_SIZE; i < nslots; i <<= 1) assert (i < (i << 1));
180 nslots = i >> SEGMENT_SIZE_SHIFT;
182 table->nseg = table->p = table->nkey = 0;
183 table->maxp = nslots << SEGMENT_SIZE_SHIFT;
185 table->iter_tail = NULL;
187 table->free_list = NULL;
189 obstack_init (&table->obst);
192 for (i = 0; i < nslots; ++i) {
193 table->dir[i] = (Segment *)obstack_alloc (&table->obst,
194 sizeof (Segment) * SEGMENT_SIZE);
196 memset (table->dir[i], 0, sizeof (Segment) * SEGMENT_SIZE);
201 table->naccess = table->ncollision = table->ndups = 0;
202 table->max_chain_len = 0;
205 table->tag = MANGLEP(tag);
212 PMANGLE(del) (SET *table)
215 MANGLEP(tag) = table->tag;
217 obstack_free (&table->obst, NULL);
223 iter_step (SET *table)
225 if (++table->iter_j >= SEGMENT_SIZE) {
227 if (++table->iter_i >= table->nseg) {
237 MANGLEP(first) (SET *table)
239 assert (!table->iter_tail);
242 while (!table->dir[table->iter_i][table->iter_j]) {
243 if (!iter_step (table)) return NULL;
245 table->iter_tail = table->dir[table->iter_i][table->iter_j];
246 assert (table->iter_tail->entry.dptr);
247 return table->iter_tail->entry.dptr;
252 MANGLEP(next) (SET *table)
254 assert (table->iter_tail);
255 table->iter_tail = table->iter_tail->chain;
256 if (!table->iter_tail) {
258 if (!iter_step (table)) return NULL;
259 } while (!table->dir[table->iter_i][table->iter_j]);
260 table->iter_tail = table->dir[table->iter_i][table->iter_j];
262 assert (table->iter_tail->entry.dptr);
263 return table->iter_tail->entry.dptr;
267 MANGLEP(break) (SET *table)
269 assert (table->iter_tail);
270 table->iter_tail = NULL;
274 static INLINE unsigned
275 Hash (SET *table, unsigned h)
279 address = h & (table->maxp - 1);
280 if (address < (unsigned)table->p)
281 address = h & ((table->maxp << 1) - 1); /* h % (2*table->maxp) */
289 return ( ++table->nkey
290 > (table->nseg << SEGMENT_SIZE_SHIFT) * MAX_LOAD_FACTOR);
295 expand_table (SET *table)
298 int OldSegmentIndex, NewSegmentIndex;
299 int OldSegmentDir, NewSegmentDir;
306 if (table->maxp + table->p < (DIRECTORY_SIZE << SEGMENT_SIZE_SHIFT)) {
307 /* Locate the bucket to be split */
308 OldSegmentDir = table->p >> SEGMENT_SIZE_SHIFT;
309 OldSegment = table->dir[OldSegmentDir];
310 OldSegmentIndex = table->p & (SEGMENT_SIZE-1);
312 /* Expand address space; if necessary create a new segment */
313 NewAddress = table->maxp + table->p;
314 NewSegmentDir = NewAddress >> SEGMENT_SIZE_SHIFT;
315 NewSegmentIndex = NewAddress & (SEGMENT_SIZE-1);
316 if (NewSegmentIndex == 0) {
317 table->dir[NewSegmentDir] =
318 (Segment *)obstack_alloc (&table->obst,
319 sizeof(Segment) * SEGMENT_SIZE);
321 NewSegment = table->dir[NewSegmentDir];
323 /* Adjust state variables */
325 if (table->p == table->maxp) {
326 table->maxp <<= 1; /* table->maxp *= 2 */
331 /* Relocate records to the new bucket */
332 Previous = &OldSegment[OldSegmentIndex];
334 LastOfNew = &NewSegment[NewSegmentIndex];
336 while (Current != NULL) {
337 if (Hash (table, Current->entry.hash) == NewAddress) {
338 /* move to new chain */
339 *LastOfNew = Current;
340 *Previous = Current->chain;
341 LastOfNew = &Current->chain;
342 Current = Current->chain;
345 /* leave on old chain */
346 Previous = &Current->chain;
347 Current = Current->chain;
355 MANGLE(_,_search) (SET *table,
361 MANGLE(_,_action) action)
364 Segment *CurrentSegment;
366 MANGLEP(cmp_fun) cmp = table->cmp;
371 assert (!table->iter_tail);
374 MANGLEP(tag) = table->tag;
378 /* Find collision chain */
379 h = Hash (table, hash);
380 SegmentIndex = h & (SEGMENT_SIZE-1);
381 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
382 assert (CurrentSegment != NULL);
383 q = CurrentSegment[SegmentIndex];
385 /* Follow collision chain */
386 while (q && !EQUAL (cmp, q, key, size)) {
391 stat_chain_len (table, chain_len);
393 if (!q && (action != MANGLE(_,_find))) { /* not found, insert */
394 if (CurrentSegment[SegmentIndex]) stat_dup (table);
397 if (table->free_list) {
398 q = table->free_list;
399 table->free_list = table->free_list->chain;
401 q = obstack_alloc (&table->obst, sizeof (Element));
403 q->entry.dptr = (void *)key;
405 obstack_blank (&table->obst, offsetof (Element, entry.dptr));
406 obstack_grow (&table->obst, key, size);
407 q = obstack_finish (&table->obst);
408 q->entry.size = size;
410 q->chain = CurrentSegment[SegmentIndex];
411 q->entry.hash = hash;
412 CurrentSegment[SegmentIndex] = q;
414 if (loaded (table)) {
415 expand_table(table); /* doesn't affect q */
420 if (action == MANGLE(_,_hinsert)) return &q->entry;
421 return q->entry.dptr;
428 pset_remove (SET *table, const void *key, unsigned hash)
431 Segment *CurrentSegment;
433 pset_cmp_fun cmp = table->cmp;
438 assert (table && !table->iter_tail);
441 /* Find collision chain */
442 h = Hash (table, hash);
443 SegmentIndex = h & (SEGMENT_SIZE-1);
444 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
445 assert (CurrentSegment != NULL);
446 p = &CurrentSegment[SegmentIndex];
448 /* Follow collision chain */
449 while (!EQUAL (cmp, *p, key, size)) {
455 stat_chain_len (table, chain_len);
459 q->chain = table->free_list;
460 table->free_list = q;
462 return q->entry.dptr;
467 (pset_find) (SET *se, const void *key, unsigned hash)
469 return pset_find (se, key, hash);
474 (pset_insert) (SET *se, const void *key, unsigned hash)
476 return pset_insert (se, key, hash);
481 (pset_hinsert) (SET *se, const void *key, unsigned hash)
483 return pset_hinsert (se, key, hash);
489 (set_find) (set *se, const void *key, size_t size, unsigned hash)
491 return set_find (se, key, size, hash);
496 (set_insert) (set *se, const void *key, size_t size, unsigned hash)
498 return set_insert (se, key, size, hash);
503 (set_hinsert) (set *se, const void *key, size_t size, unsigned hash)
505 return set_hinsert (se, key, size, hash);