/js/lib/Socket.IO-node/support/expresso/deps/jscoverage/js/jshash.cpp

  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
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 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*/
 67static void *
 68DefaultAllocTable(void *pool, size_t size)
 69{
 70    return malloc(size);
 71}
 72
 73static void
 74DefaultFreeTable(void *pool, void *item)
 75{
 76    free(item);
 77}
 78
 79static JSHashEntry *
 80DefaultAllocEntry(void *pool, const void *key)
 81{
 82    return (JSHashEntry*) malloc(sizeof(JSHashEntry));
 83}
 84
 85static void
 86DefaultFreeEntry(void *pool, JSHashEntry *he, uintN flag)
 87{
 88    if (flag == HT_FREE_ENTRY)
 89        free(he);
 90}
 91
 92static JSHashAllocOps defaultHashAllocOps = {
 93    DefaultAllocTable, DefaultFreeTable,
 94    DefaultAllocEntry, DefaultFreeEntry
 95};
 96
 97JS_PUBLIC_API(JSHashTable *)
 98JS_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
137JS_PUBLIC_API(void)
138JS_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
169JS_PUBLIC_API(JSHashEntry **)
170JS_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
196static JSBool
197Resize(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
247JS_PUBLIC_API(JSHashEntry *)
248JS_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
278JS_PUBLIC_API(JSHashEntry *)
279JS_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
300JS_PUBLIC_API(void)
301JS_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
318JS_PUBLIC_API(JSBool)
319JS_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
334JS_PUBLIC_API(void *)
335JS_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*/
353JS_PUBLIC_API(int)
354JS_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
381out:
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
402JS_PUBLIC_API(void)
403JS_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
448JS_PUBLIC_API(int)
449JS_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
460JS_PUBLIC_API(JSHashNumber)
461JS_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
472JS_PUBLIC_API(int)
473JS_CompareValues(const void *v1, const void *v2)
474{
475    return v1 == v2;
476}