/[jscoverage]/trunk/js/jshash.cpp
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Contents of /trunk/js/jshash.cpp

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Revision 507 - (show annotations)
Sun Jan 10 07:23:34 2010 UTC (9 years, 9 months ago) by siliconforks
File size: 13319 byte(s)
Update SpiderMonkey from Firefox 3.6rc1.

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 <stdlib.h>
44 #include <string.h>
45 #include "jstypes.h"
46 #include "jsstdint.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 {
70 return malloc(size);
71 }
72
73 static void
74 DefaultFreeTable(void *pool, void *item, size_t size)
75 {
76 js_free(item);
77 }
78
79 static JSHashEntry *
80 DefaultAllocEntry(void *pool, const void *key)
81 {
82 return (JSHashEntry*) malloc(sizeof(JSHashEntry));
83 }
84
85 static void
86 DefaultFreeEntry(void *pool, JSHashEntry *he, uintN flag)
87 {
88 if (flag == HT_FREE_ENTRY)
89 js_free(he);
90 }
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 {
102 JSHashTable *ht;
103 size_t nb;
104
105 if (n <= MINBUCKETS) {
106 n = MINBUCKETSLOG2;
107 } else {
108 n = JS_CeilingLog2(n);
109 if ((int32)n < 0)
110 return NULL;
111 }
112
113 if (!allocOps) allocOps = &defaultHashAllocOps;
114
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, nb);
125 return NULL;
126 }
127 memset(ht->buckets, 0, nb);
128
129 ht->keyHash = keyHash;
130 ht->keyCompare = keyCompare;
131 ht->valueCompare = valueCompare;
132 ht->allocOps = allocOps;
133 ht->allocPriv = allocPriv;
134 return ht;
135 }
136
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;
144
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, n * sizeof ht->buckets[0]);
157 #ifdef DEBUG
158 memset(ht, 0xDB, sizeof *ht);
159 #endif
160 allocOps->freeTable(allocPriv, ht, sizeof *ht);
161 }
162
163 /*
164 * Multiplicative hash, from Knuth 6.4.
165 */
166 #define BUCKET_HEAD(ht, keyHash) \
167 (&(ht)->buckets[((keyHash) * JS_GOLDEN_RATIO) >> (ht)->shift])
168
169 JS_PUBLIC_API(JSHashEntry **)
170 JS_HashTableRawLookup(JSHashTable *ht, JSHashNumber keyHash, const void *key)
171 {
172 JSHashEntry *he, **hep, **hep0;
173
174 #ifdef JS_HASHMETER
175 ht->nlookups++;
176 #endif
177 hep = hep0 = BUCKET_HEAD(ht, keyHash);
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 JS_HASHMETER
190 ht->nsteps++;
191 #endif
192 }
193 return hep;
194 }
195
196 static JSBool
197 Resize(JSHashTable *ht, uint32 newshift)
198 {
199 size_t nb, nentries, i;
200 JSHashEntry **oldbuckets, *he, *next, **hep;
201 size_t nold = NBUCKETS(ht);
202
203 JS_ASSERT(newshift < JS_HASH_BITS);
204
205 nb = (size_t)1 << (JS_HASH_BITS - newshift);
206
207 /* Integer overflow protection. */
208 if (nb > (size_t)-1 / sizeof(JSHashEntry*))
209 return JS_FALSE;
210 nb *= sizeof(JSHashEntry*);
211
212 oldbuckets = ht->buckets;
213 ht->buckets = (JSHashEntry**)ht->allocOps->allocTable(ht->allocPriv, nb);
214 if (!ht->buckets) {
215 ht->buckets = oldbuckets;
216 return JS_FALSE;
217 }
218 memset(ht->buckets, 0, nb);
219
220 ht->shift = newshift;
221 nentries = ht->nentries;
222
223 for (i = 0; nentries != 0; i++) {
224 for (he = oldbuckets[i]; he; he = next) {
225 JS_ASSERT(nentries != 0);
226 --nentries;
227 next = he->next;
228 hep = BUCKET_HEAD(ht, he->keyHash);
229
230 /*
231 * We do not require unique entries, instead appending he to the
232 * chain starting at hep.
233 */
234 while (*hep)
235 hep = &(*hep)->next;
236 he->next = NULL;
237 *hep = he;
238 }
239 }
240 #ifdef DEBUG
241 memset(oldbuckets, 0xDB, nold * sizeof oldbuckets[0]);
242 #endif
243 ht->allocOps->freeTable(ht->allocPriv, oldbuckets,
244 nold * sizeof oldbuckets[0]);
245 return JS_TRUE;
246 }
247
248 JS_PUBLIC_API(JSHashEntry *)
249 JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **&hep,
250 JSHashNumber keyHash, const void *key, void *value)
251 {
252 uint32 n;
253 JSHashEntry *he;
254
255 /* Grow the table if it is overloaded */
256 n = NBUCKETS(ht);
257 if (ht->nentries >= OVERLOADED(n)) {
258 if (!Resize(ht, ht->shift - 1))
259 return NULL;
260 #ifdef JS_HASHMETER
261 ht->ngrows++;
262 #endif
263 hep = JS_HashTableRawLookup(ht, keyHash, key);
264 }
265
266 /* Make a new key value entry */
267 he = ht->allocOps->allocEntry(ht->allocPriv, key);
268 if (!he)
269 return NULL;
270 he->keyHash = keyHash;
271 he->key = key;
272 he->value = value;
273 he->next = *hep;
274 *hep = he;
275 ht->nentries++;
276 return he;
277 }
278
279 JS_PUBLIC_API(JSHashEntry *)
280 JS_HashTableAdd(JSHashTable *ht, const void *key, void *value)
281 {
282 JSHashNumber keyHash;
283 JSHashEntry *he, **hep;
284
285 keyHash = ht->keyHash(key);
286 hep = JS_HashTableRawLookup(ht, keyHash, key);
287 if ((he = *hep) != NULL) {
288 /* Hit; see if values match */
289 if (ht->valueCompare(he->value, value)) {
290 /* key,value pair is already present in table */
291 return he;
292 }
293 if (he->value)
294 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_VALUE);
295 he->value = value;
296 return he;
297 }
298 return JS_HashTableRawAdd(ht, hep, keyHash, key, value);
299 }
300
301 JS_PUBLIC_API(void)
302 JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he)
303 {
304 uint32 n;
305
306 *hep = he->next;
307 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
308
309 /* Shrink table if it's underloaded */
310 n = NBUCKETS(ht);
311 if (--ht->nentries < UNDERLOADED(n)) {
312 Resize(ht, ht->shift + 1);
313 #ifdef JS_HASHMETER
314 ht->nshrinks++;
315 #endif
316 }
317 }
318
319 JS_PUBLIC_API(JSBool)
320 JS_HashTableRemove(JSHashTable *ht, const void *key)
321 {
322 JSHashNumber keyHash;
323 JSHashEntry *he, **hep;
324
325 keyHash = ht->keyHash(key);
326 hep = JS_HashTableRawLookup(ht, keyHash, key);
327 if ((he = *hep) == NULL)
328 return JS_FALSE;
329
330 /* Hit; remove element */
331 JS_HashTableRawRemove(ht, hep, he);
332 return JS_TRUE;
333 }
334
335 JS_PUBLIC_API(void *)
336 JS_HashTableLookup(JSHashTable *ht, const void *key)
337 {
338 JSHashNumber keyHash;
339 JSHashEntry *he, **hep;
340
341 keyHash = ht->keyHash(key);
342 hep = JS_HashTableRawLookup(ht, keyHash, key);
343 if ((he = *hep) != NULL) {
344 return he->value;
345 }
346 return NULL;
347 }
348
349 /*
350 ** Iterate over the entries in the hash table calling func for each
351 ** entry found. Stop if "f" says to (return value & JS_ENUMERATE_STOP).
352 ** Return a count of the number of elements scanned.
353 */
354 JS_PUBLIC_API(int)
355 JS_HashTableEnumerateEntries(JSHashTable *ht, JSHashEnumerator f, void *arg)
356 {
357 JSHashEntry *he, **hep, **bucket;
358 uint32 nlimit, n, nbuckets, newlog2;
359 int rv;
360
361 nlimit = ht->nentries;
362 n = 0;
363 for (bucket = ht->buckets; n != nlimit; ++bucket) {
364 hep = bucket;
365 while ((he = *hep) != NULL) {
366 JS_ASSERT(n < nlimit);
367 rv = f(he, n, arg);
368 n++;
369 if (rv & HT_ENUMERATE_REMOVE) {
370 *hep = he->next;
371 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
372 --ht->nentries;
373 } else {
374 hep = &he->next;
375 }
376 if (rv & HT_ENUMERATE_STOP) {
377 goto out;
378 }
379 }
380 }
381
382 out:
383 /* Shrink table if removal of entries made it underloaded */
384 if (ht->nentries != nlimit) {
385 JS_ASSERT(ht->nentries < nlimit);
386 nbuckets = NBUCKETS(ht);
387 if (MINBUCKETS < nbuckets && ht->nentries < UNDERLOADED(nbuckets)) {
388 newlog2 = JS_CeilingLog2(ht->nentries);
389 if (newlog2 < MINBUCKETSLOG2)
390 newlog2 = MINBUCKETSLOG2;
391
392 /* Check that we really shrink the table. */
393 JS_ASSERT(JS_HASH_BITS - ht->shift > newlog2);
394 Resize(ht, JS_HASH_BITS - newlog2);
395 }
396 }
397 return (int)n;
398 }
399
400 #ifdef JS_HASHMETER
401 #include <stdio.h>
402
403 JS_PUBLIC_API(void)
404 JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
405 {
406 double sqsum, mean, sigma;
407 uint32 nchains, nbuckets;
408 uint32 i, n, maxChain, maxChainLen;
409 JSHashEntry *he;
410
411 sqsum = 0;
412 nchains = 0;
413 maxChain = maxChainLen = 0;
414 nbuckets = NBUCKETS(ht);
415 for (i = 0; i < nbuckets; i++) {
416 he = ht->buckets[i];
417 if (!he)
418 continue;
419 nchains++;
420 for (n = 0; he; he = he->next)
421 n++;
422 sqsum += n * n;
423 if (n > maxChainLen) {
424 maxChainLen = n;
425 maxChain = i;
426 }
427 }
428
429 mean = JS_MeanAndStdDev(nchains, ht->nentries, sqsum, &sigma);
430
431 fprintf(fp, "\nHash table statistics:\n");
432 fprintf(fp, " number of lookups: %u\n", ht->nlookups);
433 fprintf(fp, " number of entries: %u\n", ht->nentries);
434 fprintf(fp, " number of grows: %u\n", ht->ngrows);
435 fprintf(fp, " number of shrinks: %u\n", ht->nshrinks);
436 fprintf(fp, " mean steps per hash: %g\n", (double)ht->nsteps
437 / ht->nlookups);
438 fprintf(fp, "mean hash chain length: %g\n", mean);
439 fprintf(fp, " standard deviation: %g\n", sigma);
440 fprintf(fp, " max hash chain length: %u\n", maxChainLen);
441 fprintf(fp, " max hash chain: [%u]\n", maxChain);
442
443 for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
444 if (dump(he, i, fp) != HT_ENUMERATE_NEXT)
445 break;
446 }
447 #endif /* JS_HASHMETER */
448
449 JS_PUBLIC_API(int)
450 JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
451 {
452 int count;
453
454 count = JS_HashTableEnumerateEntries(ht, dump, fp);
455 #ifdef JS_HASHMETER
456 JS_HashTableDumpMeter(ht, dump, fp);
457 #endif
458 return count;
459 }
460
461 JS_PUBLIC_API(JSHashNumber)
462 JS_HashString(const void *key)
463 {
464 JSHashNumber h;
465 const unsigned char *s;
466
467 h = 0;
468 for (s = (const unsigned char *)key; *s; s++)
469 h = JS_ROTATE_LEFT32(h, 4) ^ *s;
470 return h;
471 }
472
473 JS_PUBLIC_API(int)
474 JS_CompareValues(const void *v1, const void *v2)
475 {
476 return v1 == v2;
477 }

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