| /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- |
| * vim: set ts=8 sts=4 et sw=4 tw=99: |
| * This Source Code Form is subject to the terms of the Mozilla Public |
| * License, v. 2.0. If a copy of the MPL was not distributed with this |
| * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| |
| /* |
| * PR hash table package. |
| */ |
| #include <stdlib.h> |
| #include <string.h> |
| #include "jstypes.h" |
| #include "jsutil.h" |
| #include "jshash.h" |
| |
| using namespace js; |
| |
| /* 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 js_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*) js_malloc(sizeof(JSHashEntry)); |
| } |
| |
| static void |
| DefaultFreeEntry(void *pool, JSHashEntry *he, unsigned flag) |
| { |
| if (flag == HT_FREE_ENTRY) |
| js_free(he); |
| } |
| |
| static JSHashAllocOps defaultHashAllocOps = { |
| DefaultAllocTable, DefaultFreeTable, |
| DefaultAllocEntry, DefaultFreeEntry |
| }; |
| |
| JSHashTable * |
| JS_NewHashTable(uint32_t n, JSHashFunction keyHash, |
| JSHashComparator keyCompare, JSHashComparator valueCompare, |
| JSHashAllocOps *allocOps, void *allocPriv) |
| { |
| JSHashTable *ht; |
| size_t nb; |
| |
| if (n <= MINBUCKETS) { |
| n = MINBUCKETSLOG2; |
| } else { |
| n = JS_CEILING_LOG2W(n); |
| if (int32_t(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; |
| } |
| |
| void |
| JS_HashTableDestroy(JSHashTable *ht) |
| { |
| uint32_t 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]) |
| |
| 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_t 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; |
| } |
| |
| JSHashEntry * |
| JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **&hep, |
| JSHashNumber keyHash, const void *key, void *value) |
| { |
| uint32_t 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; |
| } |
| |
| 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); |
| } |
| |
| void |
| JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he) |
| { |
| uint32_t 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 |
| } |
| } |
| |
| 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; |
| } |
| |
| 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. |
| */ |
| int |
| JS_HashTableEnumerateEntries(JSHashTable *ht, JSHashEnumerator f, void *arg) |
| { |
| JSHashEntry *he, **hep, **bucket; |
| uint32_t 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_CEILING_LOG2W(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> |
| |
| void |
| JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp) |
| { |
| double sqsum, mean, sigma; |
| uint32_t nchains, nbuckets; |
| uint32_t 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 */ |
| |
| 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; |
| } |
| |
| 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; |
| } |
| |
| int |
| JS_CompareValues(const void *v1, const void *v2) |
| { |
| return v1 == v2; |
| } |