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

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Revision 332 - (show annotations)
Thu Oct 23 19:03:33 2008 UTC (11 years, 9 months ago) by siliconforks
File size: 13194 byte(s)
Add SpiderMonkey from Firefox 3.1b1.

The following directories and files were removed:
correct/, correct.js
liveconnect/
nanojit/
t/
v8/
vprof/
xpconnect/
all JavaScript files (Y.js, call.js, if.js, math-partial-sums.js, md5.js, perfect.js, trace-test.js, trace.js)


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 {
70 return malloc(size);
71 }
72
73 static void
74 DefaultFreeTable(void *pool, void *item)
75 {
76 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 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);
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);
157 #ifdef DEBUG
158 memset(ht, 0xDB, sizeof *ht);
159 #endif
160 allocOps->freeTable(allocPriv, 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 #ifdef DEBUG
202 size_t nold = NBUCKETS(ht);
203 #endif
204
205 JS_ASSERT(newshift < JS_HASH_BITS);
206
207 nb = (size_t)1 << (JS_HASH_BITS - newshift);
208
209 /* Integer overflow protection. */
210 if (nb > (size_t)-1 / sizeof(JSHashEntry*))
211 return JS_FALSE;
212 nb *= sizeof(JSHashEntry*);
213
214 oldbuckets = ht->buckets;
215 ht->buckets = (JSHashEntry**)ht->allocOps->allocTable(ht->allocPriv, nb);
216 if (!ht->buckets) {
217 ht->buckets = oldbuckets;
218 return JS_FALSE;
219 }
220 memset(ht->buckets, 0, nb);
221
222 ht->shift = newshift;
223 nentries = ht->nentries;
224
225 for (i = 0; nentries != 0; i++) {
226 for (he = oldbuckets[i]; he; he = next) {
227 JS_ASSERT(nentries != 0);
228 --nentries;
229 next = he->next;
230 hep = BUCKET_HEAD(ht, he->keyHash);
231
232 /*
233 * Since he comes from the old table, it must be unique and we
234 * simply add it to the head of bucket chain without chain lookup.
235 */
236 he->next = *hep;
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 return JS_TRUE;
245 }
246
247 JS_PUBLIC_API(JSHashEntry *)
248 JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **hep,
249 JSHashNumber keyHash, const void *key, void *value)
250 {
251 uint32 n;
252 JSHashEntry *he;
253
254 /* Grow the table if it is overloaded */
255 n = NBUCKETS(ht);
256 if (ht->nentries >= OVERLOADED(n)) {
257 if (!Resize(ht, ht->shift - 1))
258 return NULL;
259 #ifdef JS_HASHMETER
260 ht->ngrows++;
261 #endif
262 hep = JS_HashTableRawLookup(ht, keyHash, key);
263 }
264
265 /* Make a new key value entry */
266 he = ht->allocOps->allocEntry(ht->allocPriv, key);
267 if (!he)
268 return NULL;
269 he->keyHash = keyHash;
270 he->key = key;
271 he->value = value;
272 he->next = *hep;
273 *hep = he;
274 ht->nentries++;
275 return he;
276 }
277
278 JS_PUBLIC_API(JSHashEntry *)
279 JS_HashTableAdd(JSHashTable *ht, const void *key, void *value)
280 {
281 JSHashNumber keyHash;
282 JSHashEntry *he, **hep;
283
284 keyHash = ht->keyHash(key);
285 hep = JS_HashTableRawLookup(ht, keyHash, key);
286 if ((he = *hep) != NULL) {
287 /* Hit; see if values match */
288 if (ht->valueCompare(he->value, value)) {
289 /* key,value pair is already present in table */
290 return he;
291 }
292 if (he->value)
293 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_VALUE);
294 he->value = value;
295 return he;
296 }
297 return JS_HashTableRawAdd(ht, hep, keyHash, key, value);
298 }
299
300 JS_PUBLIC_API(void)
301 JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he)
302 {
303 uint32 n;
304
305 *hep = he->next;
306 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
307
308 /* Shrink table if it's underloaded */
309 n = NBUCKETS(ht);
310 if (--ht->nentries < UNDERLOADED(n)) {
311 Resize(ht, ht->shift + 1);
312 #ifdef JS_HASHMETER
313 ht->nshrinks++;
314 #endif
315 }
316 }
317
318 JS_PUBLIC_API(JSBool)
319 JS_HashTableRemove(JSHashTable *ht, const void *key)
320 {
321 JSHashNumber keyHash;
322 JSHashEntry *he, **hep;
323
324 keyHash = ht->keyHash(key);
325 hep = JS_HashTableRawLookup(ht, keyHash, key);
326 if ((he = *hep) == NULL)
327 return JS_FALSE;
328
329 /* Hit; remove element */
330 JS_HashTableRawRemove(ht, hep, he);
331 return JS_TRUE;
332 }
333
334 JS_PUBLIC_API(void *)
335 JS_HashTableLookup(JSHashTable *ht, const void *key)
336 {
337 JSHashNumber keyHash;
338 JSHashEntry *he, **hep;
339
340 keyHash = ht->keyHash(key);
341 hep = JS_HashTableRawLookup(ht, keyHash, key);
342 if ((he = *hep) != NULL) {
343 return he->value;
344 }
345 return NULL;
346 }
347
348 /*
349 ** Iterate over the entries in the hash table calling func for each
350 ** entry found. Stop if "f" says to (return value & JS_ENUMERATE_STOP).
351 ** Return a count of the number of elements scanned.
352 */
353 JS_PUBLIC_API(int)
354 JS_HashTableEnumerateEntries(JSHashTable *ht, JSHashEnumerator f, void *arg)
355 {
356 JSHashEntry *he, **hep, **bucket;
357 uint32 nlimit, n, nbuckets, newlog2;
358 int rv;
359
360 nlimit = ht->nentries;
361 n = 0;
362 for (bucket = ht->buckets; n != nlimit; ++bucket) {
363 hep = bucket;
364 while ((he = *hep) != NULL) {
365 JS_ASSERT(n < nlimit);
366 rv = f(he, n, arg);
367 n++;
368 if (rv & HT_ENUMERATE_REMOVE) {
369 *hep = he->next;
370 ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
371 --ht->nentries;
372 } else {
373 hep = &he->next;
374 }
375 if (rv & HT_ENUMERATE_STOP) {
376 goto out;
377 }
378 }
379 }
380
381 out:
382 /* Shrink table if removal of entries made it underloaded */
383 if (ht->nentries != nlimit) {
384 JS_ASSERT(ht->nentries < nlimit);
385 nbuckets = NBUCKETS(ht);
386 if (MINBUCKETS < nbuckets && ht->nentries < UNDERLOADED(nbuckets)) {
387 newlog2 = JS_CeilingLog2(ht->nentries);
388 if (newlog2 < MINBUCKETSLOG2)
389 newlog2 = MINBUCKETSLOG2;
390
391 /* Check that we really shrink the table. */
392 JS_ASSERT(JS_HASH_BITS - ht->shift > newlog2);
393 Resize(ht, JS_HASH_BITS - newlog2);
394 }
395 }
396 return (int)n;
397 }
398
399 #ifdef JS_HASHMETER
400 #include <stdio.h>
401
402 JS_PUBLIC_API(void)
403 JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
404 {
405 double sqsum, mean, sigma;
406 uint32 nchains, nbuckets;
407 uint32 i, n, maxChain, maxChainLen;
408 JSHashEntry *he;
409
410 sqsum = 0;
411 nchains = 0;
412 maxChain = maxChainLen = 0;
413 nbuckets = NBUCKETS(ht);
414 for (i = 0; i < nbuckets; i++) {
415 he = ht->buckets[i];
416 if (!he)
417 continue;
418 nchains++;
419 for (n = 0; he; he = he->next)
420 n++;
421 sqsum += n * n;
422 if (n > maxChainLen) {
423 maxChainLen = n;
424 maxChain = i;
425 }
426 }
427
428 mean = JS_MeanAndStdDev(nchains, ht->nentries, sqsum, &sigma);
429
430 fprintf(fp, "\nHash table statistics:\n");
431 fprintf(fp, " number of lookups: %u\n", ht->nlookups);
432 fprintf(fp, " number of entries: %u\n", ht->nentries);
433 fprintf(fp, " number of grows: %u\n", ht->ngrows);
434 fprintf(fp, " number of shrinks: %u\n", ht->nshrinks);
435 fprintf(fp, " mean steps per hash: %g\n", (double)ht->nsteps
436 / ht->nlookups);
437 fprintf(fp, "mean hash chain length: %g\n", mean);
438 fprintf(fp, " standard deviation: %g\n", sigma);
439 fprintf(fp, " max hash chain length: %u\n", maxChainLen);
440 fprintf(fp, " max hash chain: [%u]\n", maxChain);
441
442 for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
443 if (dump(he, i, fp) != HT_ENUMERATE_NEXT)
444 break;
445 }
446 #endif /* JS_HASHMETER */
447
448 JS_PUBLIC_API(int)
449 JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
450 {
451 int count;
452
453 count = JS_HashTableEnumerateEntries(ht, dump, fp);
454 #ifdef JS_HASHMETER
455 JS_HashTableDumpMeter(ht, dump, fp);
456 #endif
457 return count;
458 }
459
460 JS_PUBLIC_API(JSHashNumber)
461 JS_HashString(const void *key)
462 {
463 JSHashNumber h;
464 const unsigned char *s;
465
466 h = 0;
467 for (s = (const unsigned char *)key; *s; s++)
468 h = JS_ROTATE_LEFT32(h, 4) ^ *s;
469 return h;
470 }
471
472 JS_PUBLIC_API(int)
473 JS_CompareValues(const void *v1, const void *v2)
474 {
475 return v1 == v2;
476 }

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