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 ;->
32 # define PMANGLE(pre) pre##_pset
33 # define MANGLEP(post) pset_##post
34 # define MANGLE(pre, post) pre##pset##post
35 # define EQUAL(cmp, elt, key, siz) (!(cmp) ((elt)->entry.dptr, (key)))
38 # define PMANGLE(pre) pre##_set
39 # define MANGLEP(post) set_##post
40 # define MANGLE(pre, post) pre##set##post
41 # define EQUAL(cmp, elt, key, siz) \
42 (((elt)->entry.size == (siz)) && !(cmp) ((elt)->entry.dptr, (key), (siz)))
56 #define TOBSTACK_ID MANGLEP(tag)
60 #define SEGMENT_SIZE_SHIFT 8
61 #define SEGMENT_SIZE (1 << SEGMENT_SIZE_SHIFT)
62 #define DIRECTORY_SIZE_SHIFT 8
63 #define DIRECTORY_SIZE (1 << DIRECTORY_SIZE_SHIFT)
64 #define MAX_LOAD_FACTOR 4
67 typedef struct element {
68 struct element *chain;
69 MANGLEP (entry) entry;
74 short p; /* Next bucket to be split */
75 short maxp; /* upper bound on p during expansion */
76 int nkey; /* current # keys */
77 short nseg; /* current # segments */
78 Segment *dir[DIRECTORY_SIZE];
79 MANGLEP(cmp_fun) cmp; /* function comparing entries */
81 Element *iter_tail; /* non-NULL while iterating over elts */
87 int naccess, ncollision, ndups;
99 MANGLEP(stats) (SET *table)
103 Element *q = table->free_list;
104 while (q) { q = q->chain; ++nfree; }
106 printf (" accesses collisions keys duplicates longest wasted\n%12d%12d%12d%12d%12d%12d\n",
107 table->naccess, table->ncollision, table->nkey, table->ndups, table->max_chain_len, nfree);
111 stat_chain_len (SET *table, int chain_len)
113 table->ncollision += chain_len;
114 if (table->max_chain_len < chain_len) table->max_chain_len = chain_len;
117 # define stat_access(table) (++(table)->naccess)
118 # define stat_dup(table) (++(table)->ndups)
122 # define stat_chain_len(table, chain_len) ((void)0)
123 # define stat_access(table) ((void)0)
124 # define stat_dup(table) ((void)0)
130 const char *MANGLEP(tag);
134 MANGLEP(describe) (SET *table)
140 printf ("p=%d maxp=%d nkey=%d nseg=%d\n",
141 table->p, table->maxp, table->nkey, table->nseg);
142 for (i = 0; i < table->nseg; i++) {
144 for (j = 0; j < SEGMENT_SIZE; j++) {
148 if (collide) printf ("<%3d>", collide);
149 else printf ("table");
150 printf ("[%d][%3d]: %u %p\n", i, j, ptr->entry.hash, ptr->entry.dptr);
162 (PMANGLE(new)) (MANGLEP(cmp_fun) cmp, int nslots)
165 SET *table = xmalloc (sizeof (SET));
167 /* Adjust nslots up to next power of 2, minimum SEGMENT_SIZE */
168 assert (nslots >= 0);
169 for (i = SEGMENT_SIZE; i < nslots; i <<= 1) assert (i < (i << 1));
170 nslots = i >> SEGMENT_SIZE_SHIFT;
172 table->nseg = table->p = table->nkey = 0;
173 table->maxp = nslots << SEGMENT_SIZE_SHIFT;
175 table->iter_tail = NULL;
177 table->free_list = NULL;
179 obstack_init (&table->obst);
182 for (i = 0; i < nslots; ++i) {
183 table->dir[i] = (Segment *)obstack_alloc (&table->obst,
184 sizeof (Segment) * SEGMENT_SIZE);
186 memset (table->dir[i], 0, sizeof (Segment) * SEGMENT_SIZE);
191 table->naccess = table->ncollision = table->ndups = 0;
192 table->max_chain_len = 0;
195 table->tag = MANGLEP(tag);
202 PMANGLE(del) (SET *table)
205 MANGLEP(tag) = table->tag;
207 obstack_free (&table->obst, NULL);
213 iter_step (SET *table)
215 if (++table->iter_j >= SEGMENT_SIZE) {
217 if (++table->iter_i >= table->nseg) {
227 MANGLEP(first) (SET *table)
229 assert (!table->iter_tail);
232 while (!table->dir[table->iter_i][table->iter_j]) {
233 if (!iter_step (table)) return NULL;
235 table->iter_tail = table->dir[table->iter_i][table->iter_j];
236 assert (table->iter_tail->entry.dptr);
237 return table->iter_tail->entry.dptr;
242 MANGLEP(next) (SET *table)
244 assert (table->iter_tail);
245 table->iter_tail = table->iter_tail->chain;
246 if (!table->iter_tail) {
248 if (!iter_step (table)) return NULL;
249 } while (!table->dir[table->iter_i][table->iter_j]);
250 table->iter_tail = table->dir[table->iter_i][table->iter_j];
252 assert (table->iter_tail->entry.dptr);
253 return table->iter_tail->entry.dptr;
257 MANGLEP(break) (SET *table)
259 assert (table->iter_tail);
260 table->iter_tail = NULL;
264 static inline unsigned
265 Hash (SET *table, unsigned h)
269 address = h & (table->maxp - 1);
270 if (address < (unsigned)table->p)
271 address = h & ((table->maxp << 1) - 1); /* h % (2*table->maxp) */
279 return ( ++table->nkey
280 > (table->nseg << SEGMENT_SIZE_SHIFT) * MAX_LOAD_FACTOR);
285 expand_table (SET *table)
288 int OldSegmentIndex, NewSegmentIndex;
289 int OldSegmentDir, NewSegmentDir;
296 if (table->maxp + table->p < (DIRECTORY_SIZE << SEGMENT_SIZE_SHIFT)) {
297 /* Locate the bucket to be split */
298 OldSegmentDir = table->p >> SEGMENT_SIZE_SHIFT;
299 OldSegment = table->dir[OldSegmentDir];
300 OldSegmentIndex = table->p & (SEGMENT_SIZE-1);
302 /* Expand address space; if necessary create a new segment */
303 NewAddress = table->maxp + table->p;
304 NewSegmentDir = NewAddress >> SEGMENT_SIZE_SHIFT;
305 NewSegmentIndex = NewAddress & (SEGMENT_SIZE-1);
306 if (NewSegmentIndex == 0) {
307 table->dir[NewSegmentDir] =
308 (Segment *)obstack_alloc (&table->obst,
309 sizeof(Segment) * SEGMENT_SIZE);
311 NewSegment = table->dir[NewSegmentDir];
313 /* Adjust state variables */
315 if (table->p == table->maxp) {
316 table->maxp <<= 1; /* table->maxp *= 2 */
321 /* Relocate records to the new bucket */
322 Previous = &OldSegment[OldSegmentIndex];
324 LastOfNew = &NewSegment[NewSegmentIndex];
326 while (Current != NULL) {
327 if (Hash (table, Current->entry.hash) == NewAddress) {
328 /* move to new chain */
329 *LastOfNew = Current;
330 *Previous = Current->chain;
331 LastOfNew = &Current->chain;
332 Current = Current->chain;
335 /* leave on old chain */
336 Previous = &Current->chain;
337 Current = Current->chain;
345 MANGLE(_,_search) (SET *table,
351 MANGLE(_,_action) action)
354 Segment *CurrentSegment;
356 MANGLEP(cmp_fun) cmp = table->cmp;
361 assert (!table->iter_tail);
364 MANGLEP(tag) = table->tag;
368 /* Find collision chain */
369 h = Hash (table, hash);
370 SegmentIndex = h & (SEGMENT_SIZE-1);
371 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
372 assert (CurrentSegment != NULL);
373 q = CurrentSegment[SegmentIndex];
375 /* Follow collision chain */
376 while (q && !EQUAL (cmp, q, key, size)) {
381 stat_chain_len (table, chain_len);
383 if (!q && (action != MANGLE(_,_find))) { /* not found, insert */
384 if (CurrentSegment[SegmentIndex]) stat_dup (table);
387 if (table->free_list) {
388 q = table->free_list;
389 table->free_list = table->free_list->chain;
391 q = obstack_alloc (&table->obst, sizeof (Element));
393 q->entry.dptr = (void *)key;
395 obstack_blank (&table->obst, offsetof (Element, entry.dptr));
396 obstack_grow (&table->obst, key, size);
397 q = obstack_finish (&table->obst);
398 q->entry.size = size;
400 q->chain = CurrentSegment[SegmentIndex];
401 q->entry.hash = hash;
402 CurrentSegment[SegmentIndex] = q;
404 if (loaded (table)) {
405 expand_table(table); /* doesn't affect q */
410 if (action == MANGLE(_,_hinsert)) return &q->entry;
411 return q->entry.dptr;
418 pset_remove (SET *table, const void *key, unsigned hash)
421 Segment *CurrentSegment;
423 pset_cmp_fun cmp = table->cmp;
428 assert (table && !table->iter_tail);
431 /* Find collision chain */
432 h = Hash (table, hash);
433 SegmentIndex = h & (SEGMENT_SIZE-1);
434 CurrentSegment = table->dir[h >> SEGMENT_SIZE_SHIFT];
435 assert (CurrentSegment != NULL);
436 p = &CurrentSegment[SegmentIndex];
438 /* Follow collision chain */
439 while (!EQUAL (cmp, *p, key, size)) {
445 stat_chain_len (table, chain_len);
449 q->chain = table->free_list;
450 table->free_list = q;
452 return q->entry.dptr;
457 (pset_find) (SET *se, const void *key, unsigned hash)
459 return pset_find (se, key, hash);
464 (pset_insert) (SET *se, const void *key, unsigned hash)
466 return pset_insert (se, key, hash);
471 (pset_hinsert) (SET *se, const void *key, unsigned hash)
473 return pset_hinsert (se, key, hash);
479 (set_find) (set *se, const void *key, size_t size, unsigned hash)
481 return set_find (se, key, size, hash);
486 (set_insert) (set *se, const void *key, size_t size, unsigned hash)
488 return set_insert (se, key, size, hash);
493 (set_hinsert) (set *se, const void *key, size_t size, unsigned hash)
495 return set_hinsert (se, key, size, hash);