-
Notifications
You must be signed in to change notification settings - Fork 2
/
jshash.cpp
477 lines (421 loc) · 13 KB
/
jshash.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator client code, released
* March 31, 1998.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* PR hash table package.
*/
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsstdint.h"
#include "jsbit.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jshash.h" /* Added by JSIFY */
/* Compute the number of buckets in ht */
#define NBUCKETS(ht) JS_BIT(JS_HASH_BITS - (ht)->shift)
/* The smallest table has 16 buckets */
#define MINBUCKETSLOG2 4
#define MINBUCKETS JS_BIT(MINBUCKETSLOG2)
/* Compute the maximum entries given n buckets that we will tolerate, ~90% */
#define OVERLOADED(n) ((n) - ((n) >> 3))
/* Compute the number of entries below which we shrink the table by half */
#define UNDERLOADED(n) (((n) > MINBUCKETS) ? ((n) >> 2) : 0)
/*
** Stubs for default hash allocator ops.
*/
static void *
DefaultAllocTable(void *pool, size_t size)
{
return malloc(size);
}
static void
DefaultFreeTable(void *pool, void *item, size_t size)
{
js_free(item);
}
static JSHashEntry *
DefaultAllocEntry(void *pool, const void *key)
{
return (JSHashEntry*) malloc(sizeof(JSHashEntry));
}
static void
DefaultFreeEntry(void *pool, JSHashEntry *he, uintN flag)
{
if (flag == HT_FREE_ENTRY)
js_free(he);
}
static JSHashAllocOps defaultHashAllocOps = {
DefaultAllocTable, DefaultFreeTable,
DefaultAllocEntry, DefaultFreeEntry
};
JS_PUBLIC_API(JSHashTable *)
JS_NewHashTable(uint32 n, JSHashFunction keyHash,
JSHashComparator keyCompare, JSHashComparator valueCompare,
JSHashAllocOps *allocOps, void *allocPriv)
{
JSHashTable *ht;
size_t nb;
if (n <= MINBUCKETS) {
n = MINBUCKETSLOG2;
} else {
n = JS_CeilingLog2(n);
if ((int32)n < 0)
return NULL;
}
if (!allocOps) allocOps = &defaultHashAllocOps;
ht = (JSHashTable*) allocOps->allocTable(allocPriv, sizeof *ht);
if (!ht)
return NULL;
memset(ht, 0, sizeof *ht);
ht->shift = JS_HASH_BITS - n;
n = JS_BIT(n);
nb = n * sizeof(JSHashEntry *);
ht->buckets = (JSHashEntry**) allocOps->allocTable(allocPriv, nb);
if (!ht->buckets) {
allocOps->freeTable(allocPriv, ht, nb);
return NULL;
}
memset(ht->buckets, 0, nb);
ht->keyHash = keyHash;
ht->keyCompare = keyCompare;
ht->valueCompare = valueCompare;
ht->allocOps = allocOps;
ht->allocPriv = allocPriv;
return ht;
}
JS_PUBLIC_API(void)
JS_HashTableDestroy(JSHashTable *ht)
{
uint32 i, n;
JSHashEntry *he, **hep;
JSHashAllocOps *allocOps = ht->allocOps;
void *allocPriv = ht->allocPriv;
n = NBUCKETS(ht);
for (i = 0; i < n; i++) {
hep = &ht->buckets[i];
while ((he = *hep) != NULL) {
*hep = he->next;
allocOps->freeEntry(allocPriv, he, HT_FREE_ENTRY);
}
}
#ifdef DEBUG
memset(ht->buckets, 0xDB, n * sizeof ht->buckets[0]);
#endif
allocOps->freeTable(allocPriv, ht->buckets, n * sizeof ht->buckets[0]);
#ifdef DEBUG
memset(ht, 0xDB, sizeof *ht);
#endif
allocOps->freeTable(allocPriv, ht, sizeof *ht);
}
/*
* Multiplicative hash, from Knuth 6.4.
*/
#define BUCKET_HEAD(ht, keyHash) \
(&(ht)->buckets[((keyHash) * JS_GOLDEN_RATIO) >> (ht)->shift])
JS_PUBLIC_API(JSHashEntry **)
JS_HashTableRawLookup(JSHashTable *ht, JSHashNumber keyHash, const void *key)
{
JSHashEntry *he, **hep, **hep0;
#ifdef JS_HASHMETER
ht->nlookups++;
#endif
hep = hep0 = BUCKET_HEAD(ht, keyHash);
while ((he = *hep) != NULL) {
if (he->keyHash == keyHash && ht->keyCompare(key, he->key)) {
/* Move to front of chain if not already there */
if (hep != hep0) {
*hep = he->next;
he->next = *hep0;
*hep0 = he;
}
return hep0;
}
hep = &he->next;
#ifdef JS_HASHMETER
ht->nsteps++;
#endif
}
return hep;
}
static JSBool
Resize(JSHashTable *ht, uint32 newshift)
{
size_t nb, nentries, i;
JSHashEntry **oldbuckets, *he, *next, **hep;
size_t nold = NBUCKETS(ht);
JS_ASSERT(newshift < JS_HASH_BITS);
nb = (size_t)1 << (JS_HASH_BITS - newshift);
/* Integer overflow protection. */
if (nb > (size_t)-1 / sizeof(JSHashEntry*))
return JS_FALSE;
nb *= sizeof(JSHashEntry*);
oldbuckets = ht->buckets;
ht->buckets = (JSHashEntry**)ht->allocOps->allocTable(ht->allocPriv, nb);
if (!ht->buckets) {
ht->buckets = oldbuckets;
return JS_FALSE;
}
memset(ht->buckets, 0, nb);
ht->shift = newshift;
nentries = ht->nentries;
for (i = 0; nentries != 0; i++) {
for (he = oldbuckets[i]; he; he = next) {
JS_ASSERT(nentries != 0);
--nentries;
next = he->next;
hep = BUCKET_HEAD(ht, he->keyHash);
/*
* We do not require unique entries, instead appending he to the
* chain starting at hep.
*/
while (*hep)
hep = &(*hep)->next;
he->next = NULL;
*hep = he;
}
}
#ifdef DEBUG
memset(oldbuckets, 0xDB, nold * sizeof oldbuckets[0]);
#endif
ht->allocOps->freeTable(ht->allocPriv, oldbuckets,
nold * sizeof oldbuckets[0]);
return JS_TRUE;
}
JS_PUBLIC_API(JSHashEntry *)
JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **&hep,
JSHashNumber keyHash, const void *key, void *value)
{
uint32 n;
JSHashEntry *he;
/* Grow the table if it is overloaded */
n = NBUCKETS(ht);
if (ht->nentries >= OVERLOADED(n)) {
if (!Resize(ht, ht->shift - 1))
return NULL;
#ifdef JS_HASHMETER
ht->ngrows++;
#endif
hep = JS_HashTableRawLookup(ht, keyHash, key);
}
/* Make a new key value entry */
he = ht->allocOps->allocEntry(ht->allocPriv, key);
if (!he)
return NULL;
he->keyHash = keyHash;
he->key = key;
he->value = value;
he->next = *hep;
*hep = he;
ht->nentries++;
return he;
}
JS_PUBLIC_API(JSHashEntry *)
JS_HashTableAdd(JSHashTable *ht, const void *key, void *value)
{
JSHashNumber keyHash;
JSHashEntry *he, **hep;
keyHash = ht->keyHash(key);
hep = JS_HashTableRawLookup(ht, keyHash, key);
if ((he = *hep) != NULL) {
/* Hit; see if values match */
if (ht->valueCompare(he->value, value)) {
/* key,value pair is already present in table */
return he;
}
if (he->value)
ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_VALUE);
he->value = value;
return he;
}
return JS_HashTableRawAdd(ht, hep, keyHash, key, value);
}
JS_PUBLIC_API(void)
JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he)
{
uint32 n;
*hep = he->next;
ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
/* Shrink table if it's underloaded */
n = NBUCKETS(ht);
if (--ht->nentries < UNDERLOADED(n)) {
Resize(ht, ht->shift + 1);
#ifdef JS_HASHMETER
ht->nshrinks++;
#endif
}
}
JS_PUBLIC_API(JSBool)
JS_HashTableRemove(JSHashTable *ht, const void *key)
{
JSHashNumber keyHash;
JSHashEntry *he, **hep;
keyHash = ht->keyHash(key);
hep = JS_HashTableRawLookup(ht, keyHash, key);
if ((he = *hep) == NULL)
return JS_FALSE;
/* Hit; remove element */
JS_HashTableRawRemove(ht, hep, he);
return JS_TRUE;
}
JS_PUBLIC_API(void *)
JS_HashTableLookup(JSHashTable *ht, const void *key)
{
JSHashNumber keyHash;
JSHashEntry *he, **hep;
keyHash = ht->keyHash(key);
hep = JS_HashTableRawLookup(ht, keyHash, key);
if ((he = *hep) != NULL) {
return he->value;
}
return NULL;
}
/*
** Iterate over the entries in the hash table calling func for each
** entry found. Stop if "f" says to (return value & JS_ENUMERATE_STOP).
** Return a count of the number of elements scanned.
*/
JS_PUBLIC_API(int)
JS_HashTableEnumerateEntries(JSHashTable *ht, JSHashEnumerator f, void *arg)
{
JSHashEntry *he, **hep, **bucket;
uint32 nlimit, n, nbuckets, newlog2;
int rv;
nlimit = ht->nentries;
n = 0;
for (bucket = ht->buckets; n != nlimit; ++bucket) {
hep = bucket;
while ((he = *hep) != NULL) {
JS_ASSERT(n < nlimit);
rv = f(he, n, arg);
n++;
if (rv & HT_ENUMERATE_REMOVE) {
*hep = he->next;
ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
--ht->nentries;
} else {
hep = &he->next;
}
if (rv & HT_ENUMERATE_STOP) {
goto out;
}
}
}
out:
/* Shrink table if removal of entries made it underloaded */
if (ht->nentries != nlimit) {
JS_ASSERT(ht->nentries < nlimit);
nbuckets = NBUCKETS(ht);
if (MINBUCKETS < nbuckets && ht->nentries < UNDERLOADED(nbuckets)) {
newlog2 = JS_CeilingLog2(ht->nentries);
if (newlog2 < MINBUCKETSLOG2)
newlog2 = MINBUCKETSLOG2;
/* Check that we really shrink the table. */
JS_ASSERT(JS_HASH_BITS - ht->shift > newlog2);
Resize(ht, JS_HASH_BITS - newlog2);
}
}
return (int)n;
}
#ifdef JS_HASHMETER
#include <stdio.h>
JS_PUBLIC_API(void)
JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
{
double sqsum, mean, sigma;
uint32 nchains, nbuckets;
uint32 i, n, maxChain, maxChainLen;
JSHashEntry *he;
sqsum = 0;
nchains = 0;
maxChain = maxChainLen = 0;
nbuckets = NBUCKETS(ht);
for (i = 0; i < nbuckets; i++) {
he = ht->buckets[i];
if (!he)
continue;
nchains++;
for (n = 0; he; he = he->next)
n++;
sqsum += n * n;
if (n > maxChainLen) {
maxChainLen = n;
maxChain = i;
}
}
mean = JS_MeanAndStdDev(nchains, ht->nentries, sqsum, &sigma);
fprintf(fp, "\nHash table statistics:\n");
fprintf(fp, " number of lookups: %u\n", ht->nlookups);
fprintf(fp, " number of entries: %u\n", ht->nentries);
fprintf(fp, " number of grows: %u\n", ht->ngrows);
fprintf(fp, " number of shrinks: %u\n", ht->nshrinks);
fprintf(fp, " mean steps per hash: %g\n", (double)ht->nsteps
/ ht->nlookups);
fprintf(fp, "mean hash chain length: %g\n", mean);
fprintf(fp, " standard deviation: %g\n", sigma);
fprintf(fp, " max hash chain length: %u\n", maxChainLen);
fprintf(fp, " max hash chain: [%u]\n", maxChain);
for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
if (dump(he, i, fp) != HT_ENUMERATE_NEXT)
break;
}
#endif /* JS_HASHMETER */
JS_PUBLIC_API(int)
JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
{
int count;
count = JS_HashTableEnumerateEntries(ht, dump, fp);
#ifdef JS_HASHMETER
JS_HashTableDumpMeter(ht, dump, fp);
#endif
return count;
}
JS_PUBLIC_API(JSHashNumber)
JS_HashString(const void *key)
{
JSHashNumber h;
const unsigned char *s;
h = 0;
for (s = (const unsigned char *)key; *s; s++)
h = JS_ROTATE_LEFT32(h, 4) ^ *s;
return h;
}
JS_PUBLIC_API(int)
JS_CompareValues(const void *v1, const void *v2)
{
return v1 == v2;
}