diff options
Diffstat (limited to 'src/third_party/js-1.7/jshash.c')
-rw-r--r-- | src/third_party/js-1.7/jshash.c | 483 |
1 files changed, 483 insertions, 0 deletions
diff --git a/src/third_party/js-1.7/jshash.c b/src/third_party/js-1.7/jshash.c new file mode 100644 index 00000000000..8e25517d5c0 --- /dev/null +++ b/src/third_party/js-1.7/jshash.c @@ -0,0 +1,483 @@ +/* -*- 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 "jsstddef.h" +#include <stdlib.h> +#include <string.h> +#include "jstypes.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) +{ + 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) + 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); + 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); +#ifdef DEBUG + memset(ht, 0xDB, sizeof *ht); +#endif + allocOps->freeTable(allocPriv, 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 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 HASHMETER + ht->nsteps++; +#endif + } + return hep; +} + +static JSBool +Resize(JSHashTable *ht, uint32 newshift) +{ + size_t nb, nentries, i; + JSHashEntry **oldbuckets, *he, *next, **hep; +#ifdef DEBUG + size_t nold = NBUCKETS(ht); +#endif + + 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); + + /* + * Since he comes from the old table, it must be unique and we + * simply add it to the head of bucket chain without chain lookup. + */ + he->next = *hep; + *hep = he; + } + } +#ifdef DEBUG + memset(oldbuckets, 0xDB, nold * sizeof oldbuckets[0]); +#endif + ht->allocOps->freeTable(ht->allocPriv, oldbuckets); + 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 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 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 HASHMETER +#include <math.h> +#include <stdio.h> + +JS_PUBLIC_API(void) +JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp) +{ + double sqsum, mean, variance, sigma; + uint32 nchains, nbuckets, nentries; + uint32 i, n, maxChain, maxChainLen; + JSHashEntry *he; + + sqsum = 0; + nchains = 0; + 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; + } + } + nentries = ht->nentries; + mean = (double)nentries / nchains; + variance = nchains * sqsum - nentries * nentries; + if (variance < 0 || nchains == 1) + variance = 0; + else + variance /= nchains * (nchains - 1); + sigma = sqrt(variance); + + 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 /* HASHMETER */ + +JS_PUBLIC_API(int) +JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp) +{ + int count; + + count = JS_HashTableEnumerateEntries(ht, dump, fp); +#ifdef 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 = (h >> (JS_HASH_BITS - 4)) ^ (h << 4) ^ *s; + return h; +} + +JS_PUBLIC_API(int) +JS_CompareValues(const void *v1, const void *v2) +{ + return v1 == v2; +} |