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Diffstat (limited to 'runtime/hashtable.c')
| -rw-r--r-- | runtime/hashtable.c | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/runtime/hashtable.c b/runtime/hashtable.c new file mode 100644 index 0000000..4673a50 --- /dev/null +++ b/runtime/hashtable.c @@ -0,0 +1,341 @@ +/* Copyright (C) 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */ +/* taken from http://www.cl.cam.ac.uk/~cwc22/hashtable/ */ + +#include "hashtable_private.h" +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <math.h> + +/* this code has several warnings, but we ignore them because + * this seems to work and we do not want to engage in that code body. If + * we really run into troubles, it is better to change to libfastjson, which + * we should do in the medium to long term anyhow... + */ +#ifdef __GNUC__ +#pragma GCC diagnostic ignored "-Wredundant-decls" +#endif + +/* +Credit for primes table: Aaron Krowne +http://br.endernet.org/~akrowne/ +http://planetmath.org/encyclopedia/GoodHashTablePrimes.html +*/ +static const unsigned int primes[] = { +53, 97, 193, 389, +769, 1543, 3079, 6151, +12289, 24593, 49157, 98317, +196613, 393241, 786433, 1572869, +3145739, 6291469, 12582917, 25165843, +50331653, 100663319, 201326611, 402653189, +805306457, 1610612741 +}; +const unsigned int prime_table_length = sizeof(primes)/sizeof(primes[0]); + +#define MAX_LOAD_FACTOR 65 /* to get real factor, divide by 100! */ + +/* compute max load. We use a constant factor of 0.65, but do + * everything times 100, so that we do not need floats. + */ +static inline unsigned +getLoadLimit(unsigned size) +{ + return (unsigned int) ((unsigned long long) size * MAX_LOAD_FACTOR) / 100; +} + +/*****************************************************************************/ +struct hashtable * +create_hashtable(unsigned int minsize, + unsigned int (*hashf) (void*), + int (*eqf) (void*,void*), void (*dest)(void*)) +{ + struct hashtable *h; + unsigned int pindex, size = primes[0]; + /* Check requested hashtable isn't too large */ + if (minsize > (1u << 30)) return NULL; + /* Enforce size as prime */ + for (pindex=0; pindex < prime_table_length; pindex++) { + if (primes[pindex] > minsize) { size = primes[pindex]; break; } + } + h = (struct hashtable *)malloc(sizeof(struct hashtable)); + if (NULL == h) return NULL; /*oom*/ + h->table = (struct entry **)malloc(sizeof(struct entry*) * size); + if (NULL == h->table) { free(h); return NULL; } /*oom*/ + memset(h->table, 0, size * sizeof(struct entry *)); + h->tablelength = size; + h->primeindex = pindex; + h->entrycount = 0; + h->hashfn = hashf; + h->eqfn = eqf; + h->dest = dest; + h->loadlimit = getLoadLimit(size); + return h; +} + +/*****************************************************************************/ +#if defined(__clang__) +#pragma GCC diagnostic ignored "-Wunknown-attributes" +#endif +unsigned int +#if defined(__clang__) +__attribute__((no_sanitize("unsigned-integer-overflow"))) +#endif +hash(struct hashtable *h, void *k) +{ + /* Aim to protect against poor hash functions by adding logic here + * - logic taken from java 1.4 hashtable source */ + unsigned int i = h->hashfn(k); + i += ~(i << 9); + i ^= ((i >> 14) | (i << 18)); /* >>> */ + i += (i << 4); + i ^= ((i >> 10) | (i << 22)); /* >>> */ + return i; +} + +/*****************************************************************************/ +static int +hashtable_expand(struct hashtable *h) +{ + /* Double the size of the table to accomodate more entries */ + struct entry **newtable; + struct entry *e; + struct entry **pE; + unsigned int newsize, i, idx; + /* Check we're not hitting max capacity */ + if (h->primeindex == (prime_table_length - 1)) return 0; + newsize = primes[++(h->primeindex)]; + + newtable = (struct entry **)malloc(sizeof(struct entry*) * newsize); + if (NULL != newtable) + { + memset(newtable, 0, newsize * sizeof(struct entry *)); + /* This algorithm is not 'stable'. ie. it reverses the list + * when it transfers entries between the tables */ + for (i = 0; i < h->tablelength; i++) { + while (NULL != (e = h->table[i])) { + h->table[i] = e->next; + idx = indexFor(newsize,e->h); + e->next = newtable[idx]; + newtable[idx] = e; + } + } + free(h->table); + h->table = newtable; + } + /* Plan B: realloc instead */ + else + { + newtable = (struct entry **) + realloc(h->table, newsize * sizeof(struct entry *)); + if (NULL == newtable) { (h->primeindex)--; return 0; } + h->table = newtable; + memset(newtable[h->tablelength], 0, newsize - h->tablelength); + for (i = 0; i < h->tablelength; i++) { + for (pE = &(newtable[i]), e = *pE; e != NULL; e = *pE) { + idx = indexFor(newsize,e->h); + if (idx == i) + { + pE = &(e->next); + } + else + { + *pE = e->next; + e->next = newtable[idx]; + newtable[idx] = e; + } + } + } + } + h->tablelength = newsize; + h->loadlimit = getLoadLimit(newsize); + return -1; +} + +/*****************************************************************************/ +unsigned int +hashtable_count(struct hashtable *h) +{ + return h->entrycount; +} + +/*****************************************************************************/ +int +hashtable_insert(struct hashtable *h, void *k, void *v) +{ + /* This method allows duplicate keys - but they shouldn't be used */ + unsigned int idx; + struct entry *e; + if (++(h->entrycount) > h->loadlimit) + { + /* Ignore the return value. If expand fails, we should + * still try cramming just this value into the existing table + * -- we may not have memory for a larger table, but one more + * element may be ok. Next time we insert, we'll try expanding again.*/ + hashtable_expand(h); + } + e = (struct entry *)malloc(sizeof(struct entry)); + if (NULL == e) { --(h->entrycount); return 0; } /*oom*/ + e->h = hash(h,k); + idx = indexFor(h->tablelength,e->h); + e->k = k; + e->v = v; + e->next = h->table[idx]; + h->table[idx] = e; + return -1; +} + +/*****************************************************************************/ +void * /* returns value associated with key */ +hashtable_search(struct hashtable *h, void *k) +{ + struct entry *e; + unsigned int hashvalue, idx; + hashvalue = hash(h,k); + idx = indexFor(h->tablelength,hashvalue); + e = h->table[idx]; + while (NULL != e) + { + /* Check hash value to short circuit heavier comparison */ + if ((hashvalue == e->h) && (h->eqfn(k, e->k))) return e->v; + e = e->next; + } + return NULL; +} + +/*****************************************************************************/ +void * /* returns value associated with key */ +hashtable_remove(struct hashtable *h, void *k) +{ + /* TODO: consider compacting the table when the load factor drops enough, + * or provide a 'compact' method. */ + + struct entry *e; + struct entry **pE; + void *v; + unsigned int hashvalue, idx; + + hashvalue = hash(h,k); + idx = indexFor(h->tablelength,hash(h,k)); + pE = &(h->table[idx]); + e = *pE; + while (NULL != e) + { + /* Check hash value to short circuit heavier comparison */ + if ((hashvalue == e->h) && (h->eqfn(k, e->k))) + { + *pE = e->next; + h->entrycount--; + v = e->v; + freekey(e->k); + free(e); + return v; + } + pE = &(e->next); + e = e->next; + } + return NULL; +} + +/*****************************************************************************/ +/* destroy */ +void +hashtable_destroy(struct hashtable *h, int free_values) +{ + unsigned int i; + struct entry *e, *f; + struct entry **table = h->table; + if (free_values) + { + for (i = 0; i < h->tablelength; i++) + { + e = table[i]; + while (NULL != e) + { + f = e; + e = e->next; + freekey(f->k); + if(h->dest == NULL) + free(f->v); + else + h->dest(f->v); + free(f); + } + } + } + else + { + for (i = 0; i < h->tablelength; i++) + { + e = table[i]; + while (NULL != e) + { f = e; e = e->next; freekey(f->k); free(f); } + } + } + free(h->table); + free(h); +} + +/* some generic hash functions */ + +/* one provided by Aaaron Wiebe based on perl's hashing algorithm + * (so probably pretty generic). Not for excessively large strings! + */ +#if defined(__clang__) +#pragma GCC diagnostic ignored "-Wunknown-attributes" +#endif +unsigned __attribute__((nonnull(1))) int +#if defined(__clang__) +__attribute__((no_sanitize("unsigned-integer-overflow"))) +#endif +hash_from_string(void *k) +{ + char *rkey = (char*) k; + unsigned hashval = 1; + + while (*rkey) + hashval = hashval * 33 + *rkey++; + + return hashval; +} + + +int +key_equals_string(void *key1, void *key2) +{ + /* we must return true IF the keys are equal! */ + return !strcmp(key1, key2); +} + + +/* + * Copyright (c) 2002, Christopher Clark + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * * Neither the name of the original author; nor the names of any contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER + * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +*/ |