1 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 *
3 * ***** BEGIN LICENSE BLOCK *****
4 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
5 *
6 * The contents of this file are subject to the Mozilla Public License Version
7 * 1.1 (the "License"); you may not use this file except in compliance with
8 * the License. You may obtain a copy of the License at
9 * http://www.mozilla.org/MPL/
10 *
11 * Software distributed under the License is distributed on an "AS IS" basis,
12 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13 * for the specific language governing rights and limitations under the
14 * License.
15 *
16 * The Original Code is Mozilla Communicator client code, released
17 * March 31, 1998.
18 *
19 * The Initial Developer of the Original Code is
20 * Netscape Communications Corporation.
21 * Portions created by the Initial Developer are Copyright (C) 1998
22 * the Initial Developer. All Rights Reserved.
23 *
24 * Contributor(s):
25 *
26 * Alternatively, the contents of this file may be used under the terms of
27 * either of the GNU General Public License Version 2 or later (the "GPL"),
28 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
29 * in which case the provisions of the GPL or the LGPL are applicable instead
30 * of those above. If you wish to allow use of your version of this file only
31 * under the terms of either the GPL or the LGPL, and not to allow others to
32 * use your version of this file under the terms of the MPL, indicate your
33 * decision by deleting the provisions above and replace them with the notice
34 * and other provisions required by the GPL or the LGPL. If you do not delete
35 * the provisions above, a recipient may use your version of this file under
36 * the terms of any one of the MPL, the GPL or the LGPL.
37 *
38 * ***** END LICENSE BLOCK ***** */
40 /*
41 * PR hash table package.
42 */
43 #include "jsstddef.h"
44 #include <stdlib.h>
45 #include <string.h>
46 #include "jstypes.h"
47 #include "jsbit.h"
48 #include "jsutil.h" /* Added by JSIFY */
49 #include "jshash.h" /* Added by JSIFY */
51 /* Compute the number of buckets in ht */
52 #define NBUCKETS(ht) JS_BIT(JS_HASH_BITS - (ht)->shift)
54 /* The smallest table has 16 buckets */
55 #define MINBUCKETSLOG2 4
56 #define MINBUCKETS JS_BIT(MINBUCKETSLOG2)
58 /* Compute the maximum entries given n buckets that we will tolerate, ~90% */
59 #define OVERLOADED(n) ((n) - ((n) >> 3))
61 /* Compute the number of entries below which we shrink the table by half */
62 #define UNDERLOADED(n) (((n) > MINBUCKETS) ? ((n) >> 2) : 0)
64 /*
65 ** Stubs for default hash allocator ops.
66 */
67 static void *
68 DefaultAllocTable(void *pool, size_t size)
69 {
70 return malloc(size);
71 }
73 static void
74 DefaultFreeTable(void *pool, void *item)
75 {
76 free(item);
77 }
79 static JSHashEntry *
80 DefaultAllocEntry(void *pool, const void *key)
81 {
82 return (JSHashEntry*) malloc(sizeof(JSHashEntry));
83 }
85 static void
86 DefaultFreeEntry(void *pool, JSHashEntry *he, uintN flag)
87 {
88 if (flag == HT_FREE_ENTRY)
89 free(he);
90 }
92 static JSHashAllocOps defaultHashAllocOps = {
93 DefaultAllocTable, DefaultFreeTable,
94 DefaultAllocEntry, DefaultFreeEntry
95 };
97 JS_PUBLIC_API(JSHashTable *)
98 JS_NewHashTable(uint32 n, JSHashFunction keyHash,
99 JSHashComparator keyCompare, JSHashComparator valueCompare,
100 JSHashAllocOps *allocOps, void *allocPriv)
101 {
102 JSHashTable *ht;
103 size_t nb;
105 if (n <= MINBUCKETS) {
106 n = MINBUCKETSLOG2;
107 } else {
108 n = JS_CeilingLog2(n);
109 if ((int32)n < 0)
110 return NULL;
111 }
113 if (!allocOps) allocOps = &defaultHashAllocOps;
115 ht = (JSHashTable*) allocOps->allocTable(allocPriv, sizeof *ht);
116 if (!ht)
117 return NULL;
118 memset(ht, 0, sizeof *ht);
119 ht->shift = JS_HASH_BITS - n;
120 n = JS_BIT(n);
121 nb = n * sizeof(JSHashEntry *);
122 ht->buckets = (JSHashEntry**) allocOps->allocTable(allocPriv, nb);
123 if (!ht->buckets) {
124 allocOps->freeTable(allocPriv, ht);
125 return NULL;
126 }
127 memset(ht->buckets, 0, nb);
129 ht->keyHash = keyHash;
130 ht->keyCompare = keyCompare;
131 ht->valueCompare = valueCompare;
132 ht->allocOps = allocOps;
133 ht->allocPriv = allocPriv;
134 return ht;
135 }
137 JS_PUBLIC_API(void)
138 JS_HashTableDestroy(JSHashTable *ht)
139 {
140 uint32 i, n;
141 JSHashEntry *he, **hep;
142 JSHashAllocOps *allocOps = ht->allocOps;
143 void *allocPriv = ht->allocPriv;
145 n = NBUCKETS(ht);
146 for (i = 0; i < n; i++) {
147 hep = &ht->buckets[i];
148 while ((he = *hep) != NULL) {
149 *hep = he->next;
150 allocOps->freeEntry(allocPriv, he, HT_FREE_ENTRY);
151 }
152 }
153 #ifdef DEBUG
154 memset(ht->buckets, 0xDB, n * sizeof ht->buckets[0]);
155 #endif
156 allocOps->freeTable(allocPriv, ht->buckets);
157 #ifdef DEBUG
158 memset(ht, 0xDB, sizeof *ht);
159 #endif
160 allocOps->freeTable(allocPriv, ht);
161 }
163 /*
164 ** Multiplicative hash, from Knuth 6.4.
165 */
166 JS_PUBLIC_API(JSHashEntry **)
167 JS_HashTableRawLookup(JSHashTable *ht, JSHashNumber keyHash, const void *key)
168 {
169 JSHashEntry *he, **hep, **hep0;
170 JSHashNumber h;
172 #ifdef HASHMETER
173 ht->nlookups++;
174 #endif
175 h = keyHash * JS_GOLDEN_RATIO;
176 h >>= ht->shift;
177 hep = hep0 = &ht->buckets[h];
178 while ((he = *hep) != NULL) {
179 if (he->keyHash == keyHash && ht->keyCompare(key, he->key)) {
180 /* Move to front of chain if not already there */
181 if (hep != hep0) {
182 *hep = he->next;
183 he->next = *hep0;
184 *hep0 = he;
185 }
186 return hep0;
187 }
188 hep = &he->next;
189 #ifdef HASHMETER
190 ht->nsteps++;
191 #endif
192 }
193 return hep;
194 }
196 JS_PUBLIC_API(JSHashEntry *)
197 JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **hep,
198 JSHashNumber keyHash, const void *key, void *value)
199 {
200 uint32 i, n;
201 JSHashEntry *he, *next, **oldbuckets;
202 size_t nb;
204 /* Grow the table if it is overloaded */
205 n = NBUCKETS(ht);
206 if (ht->nentries >= OVERLOADED(n)) {
207 oldbuckets = ht->buckets;
208 nb = 2 * n * sizeof(JSHashEntry *);
209 ht->buckets = (JSHashEntry**)
210 ht->allocOps->allocTable(ht->allocPriv, nb);
211 if (!ht->buckets) {
212 ht->buckets = oldbuckets;
213 return NULL;
214 }
215 memset(ht->buckets, 0, nb);
216 #ifdef HASHMETER
217 ht->ngrows++;
218 #endif
219 ht->shift--;
221 for (i = 0; i < n; i++) {
222 for (he = oldbuckets[i]; he; he = next) {
223 next = he->next;
224 hep = JS_HashTableRawLookup(ht, he->keyHash, he->key);
225 JS_ASSERT(*hep == NULL);
226 he->next = NULL;
227 *hep = he;
228 }
229 }
230 #ifdef DEBUG
231 memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
232 #endif
233 ht->allocOps->freeTable(ht->allocPriv, oldbuckets);
234 hep = JS_HashTableRawLookup(ht, keyHash, key);
235 }
237 /* Make a new key value entry */
238 he = ht->allocOps->allocEntry(ht->allocPriv, key);
239 if (!he)
240 return NULL;
241 he->keyHash = keyHash;
242 he->key = key;
243 he->value = value;
244 he->next = *hep;
245 *hep = he;
246 ht->nentries++;
247 return he;
248 }
250 JS_PUBLIC_API(JSHashEntry *)
251 JS_HashTableAdd(JSHashTable *ht, const void *key, void *value)
252 {
253 JSHashNumber keyHash;
254 JSHashEntry *he, **hep;
256 keyHash = ht->keyHash(key);
257 hep = JS_HashTableRawLookup(ht, keyHash, key);
258 if ((he = *hep) != NULL) {
259 /* Hit; see if values match */
260 if (ht->valueCompare(he->value, value)) {
261 /* key,value pair is already present in table */
262 return he;
263 }
264 if (he->value)
265 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_VALUE);
266 he->value = value;
267 return he;
268 }
269 return JS_HashTableRawAdd(ht, hep, keyHash, key, value);
270 }
272 JS_PUBLIC_API(void)
273 JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he)
274 {
275 uint32 i, n;
276 JSHashEntry *next, **oldbuckets;
277 size_t nb;
279 *hep = he->next;
280 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
282 /* Shrink table if it's underloaded */
283 n = NBUCKETS(ht);
284 if (--ht->nentries < UNDERLOADED(n)) {
285 oldbuckets = ht->buckets;
286 nb = n * sizeof(JSHashEntry*) / 2;
287 ht->buckets = (JSHashEntry**)
288 ht->allocOps->allocTable(ht->allocPriv, nb);
289 if (!ht->buckets) {
290 ht->buckets = oldbuckets;
291 return;
292 }
293 memset(ht->buckets, 0, nb);
294 #ifdef HASHMETER
295 ht->nshrinks++;
296 #endif
297 ht->shift++;
299 for (i = 0; i < n; i++) {
300 for (he = oldbuckets[i]; he; he = next) {
301 next = he->next;
302 hep = JS_HashTableRawLookup(ht, he->keyHash, he->key);
303 JS_ASSERT(*hep == NULL);
304 he->next = NULL;
305 *hep = he;
306 }
307 }
308 #ifdef DEBUG
309 memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
310 #endif
311 ht->allocOps->freeTable(ht->allocPriv, oldbuckets);
312 }
313 }
315 JS_PUBLIC_API(JSBool)
316 JS_HashTableRemove(JSHashTable *ht, const void *key)
317 {
318 JSHashNumber keyHash;
319 JSHashEntry *he, **hep;
321 keyHash = ht->keyHash(key);
322 hep = JS_HashTableRawLookup(ht, keyHash, key);
323 if ((he = *hep) == NULL)
324 return JS_FALSE;
326 /* Hit; remove element */
327 JS_HashTableRawRemove(ht, hep, he);
328 return JS_TRUE;
329 }
331 JS_PUBLIC_API(void *)
332 JS_HashTableLookup(JSHashTable *ht, const void *key)
333 {
334 JSHashNumber keyHash;
335 JSHashEntry *he, **hep;
337 keyHash = ht->keyHash(key);
338 hep = JS_HashTableRawLookup(ht, keyHash, key);
339 if ((he = *hep) != NULL) {
340 return he->value;
341 }
342 return NULL;
343 }
345 /*
346 ** Iterate over the entries in the hash table calling func for each
347 ** entry found. Stop if "f" says to (return value & JS_ENUMERATE_STOP).
348 ** Return a count of the number of elements scanned.
349 */
350 JS_PUBLIC_API(int)
351 JS_HashTableEnumerateEntries(JSHashTable *ht, JSHashEnumerator f, void *arg)
352 {
353 JSHashEntry *he, **hep;
354 uint32 i, nbuckets;
355 int rv, n = 0;
356 JSHashEntry *todo = NULL;
358 nbuckets = NBUCKETS(ht);
359 for (i = 0; i < nbuckets; i++) {
360 hep = &ht->buckets[i];
361 while ((he = *hep) != NULL) {
362 rv = f(he, n, arg);
363 n++;
364 if (rv & (HT_ENUMERATE_REMOVE | HT_ENUMERATE_UNHASH)) {
365 *hep = he->next;
366 if (rv & HT_ENUMERATE_REMOVE) {
367 he->next = todo;
368 todo = he;
369 }
370 } else {
371 hep = &he->next;
372 }
373 if (rv & HT_ENUMERATE_STOP) {
374 goto out;
375 }
376 }
377 }
379 out:
380 hep = &todo;
381 while ((he = *hep) != NULL) {
382 JS_HashTableRawRemove(ht, hep, he);
383 }
384 return n;
385 }
387 #ifdef HASHMETER
388 #include <math.h>
389 #include <stdio.h>
391 JS_PUBLIC_API(void)
392 JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
393 {
394 double sqsum, mean, variance, sigma;
395 uint32 nchains, nbuckets, nentries;
396 uint32 i, n, maxChain, maxChainLen;
397 JSHashEntry *he;
399 sqsum = 0;
400 nchains = 0;
401 maxChainLen = 0;
402 nbuckets = NBUCKETS(ht);
403 for (i = 0; i < nbuckets; i++) {
404 he = ht->buckets[i];
405 if (!he)
406 continue;
407 nchains++;
408 for (n = 0; he; he = he->next)
409 n++;
410 sqsum += n * n;
411 if (n > maxChainLen) {
412 maxChainLen = n;
413 maxChain = i;
414 }
415 }
416 nentries = ht->nentries;
417 mean = (double)nentries / nchains;
418 variance = nchains * sqsum - nentries * nentries;
419 if (variance < 0 || nchains == 1)
420 variance = 0;
421 else
422 variance /= nchains * (nchains - 1);
423 sigma = sqrt(variance);
425 fprintf(fp, "\nHash table statistics:\n");
426 fprintf(fp, " number of lookups: %u\n", ht->nlookups);
427 fprintf(fp, " number of entries: %u\n", ht->nentries);
428 fprintf(fp, " number of grows: %u\n", ht->ngrows);
429 fprintf(fp, " number of shrinks: %u\n", ht->nshrinks);
430 fprintf(fp, " mean steps per hash: %g\n", (double)ht->nsteps
431 / ht->nlookups);
432 fprintf(fp, "mean hash chain length: %g\n", mean);
433 fprintf(fp, " standard deviation: %g\n", sigma);
434 fprintf(fp, " max hash chain length: %u\n", maxChainLen);
435 fprintf(fp, " max hash chain: [%u]\n", maxChain);
437 for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
438 if (dump(he, i, fp) != HT_ENUMERATE_NEXT)
439 break;
440 }
441 #endif /* HASHMETER */
443 JS_PUBLIC_API(int)
444 JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
445 {
446 int count;
448 count = JS_HashTableEnumerateEntries(ht, dump, fp);
449 #ifdef HASHMETER
450 JS_HashTableDumpMeter(ht, dump, fp);
451 #endif
452 return count;
453 }
455 JS_PUBLIC_API(JSHashNumber)
456 JS_HashString(const void *key)
457 {
458 JSHashNumber h;
459 const unsigned char *s;
461 h = 0;
462 for (s = (const unsigned char *)key; *s; s++)
463 h = (h >> (JS_HASH_BITS - 4)) ^ (h << 4) ^ *s;
464 return h;
465 }
467 JS_PUBLIC_API(int)
468 JS_CompareValues(const void *v1, const void *v2)
469 {
470 return v1 == v2;
471 }