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 ***** */
39
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 */
50
51 /* Compute the number of buckets in ht */
52 #define NBUCKETS(ht) JS_BIT(JS_HASH_BITS - (ht)->shift)
53
54 /* The smallest table has 16 buckets */
55 #define MINBUCKETSLOG2 4
56 #define MINBUCKETS JS_BIT(MINBUCKETSLOG2)
57
58 /* Compute the maximum entries given n buckets that we will tolerate, ~90% */
59 #define OVERLOADED(n) ((n) - ((n) >> 3))
60
61 /* Compute the number of entries below which we shrink the table by half */
62 #define UNDERLOADED(n) (((n) > MINBUCKETS) ? ((n) >> 2) : 0)
63
64 /*
65 ** Stubs for default hash allocator ops.
66 */
67 static void *
68 DefaultAllocTable(void *pool, size_t size)
69 580 {
70 580 return malloc(size);
71 }
72
73 static void
74 DefaultFreeTable(void *pool, void *item)
75 512 {
76 512 free(item);
77 512 }
78
79 static JSHashEntry *
80 DefaultAllocEntry(void *pool, const void *key)
81 72277 {
82 72277 return (JSHashEntry*) malloc(sizeof(JSHashEntry));
83 }
84
85 static void
86 DefaultFreeEntry(void *pool, JSHashEntry *he, uintN flag)
87 72277 {
88 72277 if (flag == HT_FREE_ENTRY)
89 72277 free(he);
90 72277 }
91
92 static JSHashAllocOps defaultHashAllocOps = {
93 DefaultAllocTable, DefaultFreeTable,
94 DefaultAllocEntry, DefaultFreeEntry
95 };
96
97 JS_PUBLIC_API(JSHashTable *)
98 JS_NewHashTable(uint32 n, JSHashFunction keyHash,
99 JSHashComparator keyCompare, JSHashComparator valueCompare,
100 JSHashAllocOps *allocOps, void *allocPriv)
101 5668 {
102 JSHashTable *ht;
103 size_t nb;
104
105 5668 if (n <= MINBUCKETS) {
106 5634 n = MINBUCKETSLOG2;
107 } else {
108 34 n = JS_CeilingLog2(n);
109 34 if ((int32)n < 0)
110 0 return NULL;
111 }
112
113 5668 if (!allocOps) allocOps = &defaultHashAllocOps;
114
115 5668 ht = (JSHashTable*) allocOps->allocTable(allocPriv, sizeof *ht);
116 5668 if (!ht)
117 0 return NULL;
118 5668 memset(ht, 0, sizeof *ht);
119 5668 ht->shift = JS_HASH_BITS - n;
120 5668 n = JS_BIT(n);
121 5668 nb = n * sizeof(JSHashEntry *);
122 5668 ht->buckets = (JSHashEntry**) allocOps->allocTable(allocPriv, nb);
123 5668 if (!ht->buckets) {
124 0 allocOps->freeTable(allocPriv, ht);
125 0 return NULL;
126 }
127 5668 memset(ht->buckets, 0, nb);
128
129 5668 ht->keyHash = keyHash;
130 5668 ht->keyCompare = keyCompare;
131 5668 ht->valueCompare = valueCompare;
132 5668 ht->allocOps = allocOps;
133 5668 ht->allocPriv = allocPriv;
134 5668 return ht;
135 }
136
137 JS_PUBLIC_API(void)
138 JS_HashTableDestroy(JSHashTable *ht)
139 68 {
140 uint32 i, n;
141 JSHashEntry *he, **hep;
142 68 JSHashAllocOps *allocOps = ht->allocOps;
143 68 void *allocPriv = ht->allocPriv;
144
145 68 n = NBUCKETS(ht);
146 59636 for (i = 0; i < n; i++) {
147 59568 hep = &ht->buckets[i];
148 138324 while ((he = *hep) != NULL) {
149 19188 *hep = he->next;
150 19188 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 68 allocOps->freeTable(allocPriv, ht->buckets);
157 #ifdef DEBUG
158 memset(ht, 0xDB, sizeof *ht);
159 #endif
160 68 allocOps->freeTable(allocPriv, ht);
161 68 }
162
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 7667381 {
169 JSHashEntry *he, **hep, **hep0;
170 JSHashNumber h;
171
172 #ifdef HASHMETER
173 ht->nlookups++;
174 #endif
175 7667381 h = keyHash * JS_GOLDEN_RATIO;
176 7667381 h >>= ht->shift;
177 7667381 hep = hep0 = &ht->buckets[h];
178 16019305 while ((he = *hep) != NULL) {
179 6856623 if (he->keyHash == keyHash && ht->keyCompare(key, he->key)) {
180 /* Move to front of chain if not already there */
181 6172080 if (hep != hep0) {
182 229031 *hep = he->next;
183 229031 he->next = *hep0;
184 229031 *hep0 = he;
185 }
186 6172080 return hep0;
187 }
188 684543 hep = &he->next;
189 #ifdef HASHMETER
190 ht->nsteps++;
191 #endif
192 }
193 1495301 return hep;
194 }
195
196 JS_PUBLIC_API(JSHashEntry *)
197 JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **hep,
198 JSHashNumber keyHash, const void *key, void *value)
199 446549 {
200 uint32 i, n;
201 JSHashEntry *he, *next, **oldbuckets;
202 size_t nb;
203
204 /* Grow the table if it is overloaded */
205 446549 n = NBUCKETS(ht);
206 446549 if (ht->nentries >= OVERLOADED(n)) {
207 10289 oldbuckets = ht->buckets;
208 10289 nb = 2 * n * sizeof(JSHashEntry *);
209 10289 ht->buckets = (JSHashEntry**)
210 ht->allocOps->allocTable(ht->allocPriv, nb);
211 10289 if (!ht->buckets) {
212 0 ht->buckets = oldbuckets;
213 0 return NULL;
214 }
215 10289 memset(ht->buckets, 0, nb);
216 #ifdef HASHMETER
217 ht->ngrows++;
218 #endif
219 10289 ht->shift--;
220
221 745697 for (i = 0; i < n; i++) {
222 1378890 for (he = oldbuckets[i]; he; he = next) {
223 643482 next = he->next;
224 643482 hep = JS_HashTableRawLookup(ht, he->keyHash, he->key);
225 JS_ASSERT(*hep == NULL);
226 643482 he->next = NULL;
227 643482 *hep = he;
228 }
229 }
230 #ifdef DEBUG
231 memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
232 #endif
233 10289 ht->allocOps->freeTable(ht->allocPriv, oldbuckets);
234 10289 hep = JS_HashTableRawLookup(ht, keyHash, key);
235 }
236
237 /* Make a new key value entry */
238 446549 he = ht->allocOps->allocEntry(ht->allocPriv, key);
239 446549 if (!he)
240 0 return NULL;
241 446549 he->keyHash = keyHash;
242 446549 he->key = key;
243 446549 he->value = value;
244 446549 he->next = *hep;
245 446549 *hep = he;
246 446549 ht->nentries++;
247 446549 return he;
248 }
249
250 JS_PUBLIC_API(JSHashEntry *)
251 JS_HashTableAdd(JSHashTable *ht, const void *key, void *value)
252 0 {
253 JSHashNumber keyHash;
254 JSHashEntry *he, **hep;
255
256 0 keyHash = ht->keyHash(key);
257 0 hep = JS_HashTableRawLookup(ht, keyHash, key);
258 0 if ((he = *hep) != NULL) {
259 /* Hit; see if values match */
260 0 if (ht->valueCompare(he->value, value)) {
261 /* key,value pair is already present in table */
262 0 return he;
263 }
264 0 if (he->value)
265 0 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_VALUE);
266 0 he->value = value;
267 0 return he;
268 }
269 0 return JS_HashTableRawAdd(ht, hep, keyHash, key, value);
270 }
271
272 JS_PUBLIC_API(void)
273 JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he)
274 162724 {
275 uint32 i, n;
276 JSHashEntry *next, **oldbuckets;
277 size_t nb;
278
279 162724 *hep = he->next;
280 162724 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
281
282 /* Shrink table if it's underloaded */
283 162724 n = NBUCKETS(ht);
284 162724 if (--ht->nentries < UNDERLOADED(n)) {
285 359 oldbuckets = ht->buckets;
286 359 nb = n * sizeof(JSHashEntry*) / 2;
287 359 ht->buckets = (JSHashEntry**)
288 ht->allocOps->allocTable(ht->allocPriv, nb);
289 359 if (!ht->buckets) {
290 0 ht->buckets = oldbuckets;
291 0 return;
292 }
293 359 memset(ht->buckets, 0, nb);
294 #ifdef HASHMETER
295 ht->nshrinks++;
296 #endif
297 359 ht->shift++;
298
299 490183 for (i = 0; i < n; i++) {
300 576007 for (he = oldbuckets[i]; he; he = next) {
301 86183 next = he->next;
302 86183 hep = JS_HashTableRawLookup(ht, he->keyHash, he->key);
303 JS_ASSERT(*hep == NULL);
304 86183 he->next = NULL;
305 86183 *hep = he;
306 }
307 }
308 #ifdef DEBUG
309 memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
310 #endif
311 359 ht->allocOps->freeTable(ht->allocPriv, oldbuckets);
312 }
313 }
314
315 JS_PUBLIC_API(JSBool)
316 JS_HashTableRemove(JSHashTable *ht, const void *key)
317 0 {
318 JSHashNumber keyHash;
319 JSHashEntry *he, **hep;
320
321 0 keyHash = ht->keyHash(key);
322 0 hep = JS_HashTableRawLookup(ht, keyHash, key);
323 0 if ((he = *hep) == NULL)
324 0 return JS_FALSE;
325
326 /* Hit; remove element */
327 0 JS_HashTableRawRemove(ht, hep, he);
328 0 return JS_TRUE;
329 }
330
331 JS_PUBLIC_API(void *)
332 JS_HashTableLookup(JSHashTable *ht, const void *key)
333 0 {
334 JSHashNumber keyHash;
335 JSHashEntry *he, **hep;
336
337 0 keyHash = ht->keyHash(key);
338 0 hep = JS_HashTableRawLookup(ht, keyHash, key);
339 0 if ((he = *hep) != NULL) {
340 0 return he->value;
341 }
342 0 return NULL;
343 }
344
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 5379 {
353 JSHashEntry *he, **hep;
354 uint32 i, nbuckets;
355 5379 int rv, n = 0;
356 5379 JSHashEntry *todo = NULL;
357
358 5379 nbuckets = NBUCKETS(ht);
359 1516243 for (i = 0; i < nbuckets; i++) {
360 1510864 hep = &ht->buckets[i];
361 3801756 while ((he = *hep) != NULL) {
362 780028 rv = f(he, n, arg);
363 780028 n++;
364 780028 if (rv & (HT_ENUMERATE_REMOVE | HT_ENUMERATE_UNHASH)) {
365 90447 *hep = he->next;
366 90447 if (rv & HT_ENUMERATE_REMOVE) {
367 90447 he->next = todo;
368 90447 todo = he;
369 }
370 } else {
371 689581 hep = &he->next;
372 }
373 780028 if (rv & HT_ENUMERATE_STOP) {
374 0 goto out;
375 }
376 }
377 }
378
379 5379 out:
380 5379 hep = &todo;
381 101205 while ((he = *hep) != NULL) {
382 90447 JS_HashTableRawRemove(ht, hep, he);
383 }
384 5379 return n;
385 }
386
387 #ifdef HASHMETER
388 #include <math.h>
389 #include <stdio.h>
390
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;
398
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);
424
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);
436
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 */
442
443 JS_PUBLIC_API(int)
444 JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
445 0 {
446 int count;
447
448 0 count = JS_HashTableEnumerateEntries(ht, dump, fp);
449 #ifdef HASHMETER
450 JS_HashTableDumpMeter(ht, dump, fp);
451 #endif
452 0 return count;
453 }
454
455 JS_PUBLIC_API(JSHashNumber)
456 JS_HashString(const void *key)
457 9914 {
458 JSHashNumber h;
459 const unsigned char *s;
460
461 9914 h = 0;
462 684196 for (s = (const unsigned char *)key; *s; s++)
463 674282 h = (h >> (JS_HASH_BITS - 4)) ^ (h << 4) ^ *s;
464 9914 return h;
465 }
466
467 JS_PUBLIC_API(int)
468 JS_CompareValues(const void *v1, const void *v2)
469 1511287 {
470 1511287 return v1 == v2;