| /* |
| * Copyright 2004,2005 The Apache Software Foundation. |
| * |
| * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "axis2_hash.h" |
| |
| #include <stdlib.h> |
| #include <string.h> |
| #include <stdio.h> |
| |
| /* |
| * The internal form of a hash table. |
| * |
| * The table is an array indexed by the hash of the key; collisions |
| * are resolved by hanging a linked list of hash entries off each |
| * element of the array. Although this is a really simple design it |
| * isn't too bad given that environments have a low allocation overhead. |
| */ |
| |
| typedef struct axis2_hash_entry_t axis2_hash_entry_t; |
| |
| struct axis2_hash_entry_t |
| { |
| axis2_hash_entry_t *next; |
| unsigned int hash; |
| const void *key; |
| axis2_ssize_t klen; |
| const void *val; |
| }; |
| |
| /* |
| * Data structure for iterating through a hash table. |
| * |
| * We keep a pointer to the next hash entry here to allow the current |
| * hash entry to be freed or otherwise mangled between calls to |
| * axis2_hash_next(). |
| */ |
| struct axis2_hash_index_t |
| { |
| axis2_hash_t *ht; |
| axis2_hash_entry_t *this, *next; |
| unsigned int index; |
| }; |
| |
| /* |
| * The size of the array is always a power of two. We use the maximum |
| * index rather than the size so that we can use bitwise-AND for |
| * modular arithmetic. |
| * The count of hash entries may be greater depending on the chosen |
| * collision rate. |
| */ |
| struct axis2_hash_t |
| { |
| axis2_env_t *environment; |
| axis2_hash_entry_t **array; |
| axis2_hash_index_t iterator; /* For axis2_hash_first(NULL, ...) */ |
| unsigned int count, max; |
| axis2_hashfunc_t hash_func; |
| axis2_hash_entry_t *free; /* List of recycled entries */ |
| }; |
| |
| #define INITIAL_MAX 15 /* tunable == 2^n - 1 */ |
| |
| |
| /* |
| * Hash creation functions. |
| */ |
| |
| static axis2_hash_entry_t ** |
| alloc_array (axis2_hash_t *ht, unsigned int max) |
| { |
| return memset (AXIS2_MALLOC (ht->environment->allocator, |
| sizeof (*ht->array) * (max + 1)), 0, |
| sizeof (*ht->array) * (max + 1)); |
| } |
| |
| AXIS2_DECLARE(axis2_hash_t*) |
| axis2_hash_make (axis2_env_t **environment) |
| { |
| axis2_hash_t *ht; |
| AXIS2_ENV_CHECK(environment, NULL); |
| |
| ht = AXIS2_MALLOC ((*environment)->allocator, sizeof (axis2_hash_t)); |
| ht->environment = (*environment); |
| ht->free = NULL; |
| ht->count = 0; |
| ht->max = INITIAL_MAX; |
| ht->array = alloc_array (ht, ht->max); |
| ht->hash_func = axis2_hashfunc_default; |
| return ht; |
| } |
| |
| AXIS2_DECLARE(axis2_hash_t*) |
| axis2_hash_make_custom (axis2_env_t **environment, |
| axis2_hashfunc_t hash_func) |
| { |
| axis2_hash_t *ht; |
| AXIS2_ENV_CHECK(environment, NULL); |
| ht = axis2_hash_make (environment); |
| ht->hash_func = hash_func; |
| return ht; |
| } |
| |
| |
| /* |
| * Hash iteration functions. |
| */ |
| |
| AXIS2_DECLARE(axis2_hash_index_t*) |
| axis2_hash_next (axis2_env_t **environment, axis2_hash_index_t *hi) |
| { |
| hi->this = hi->next; |
| while (!hi->this) |
| { |
| if (hi->index > hi->ht->max) |
| { |
| if (environment && *environment) |
| AXIS2_FREE ((*environment)->allocator, hi); |
| return NULL; |
| } |
| |
| hi->this = hi->ht->array[hi->index++]; |
| } |
| hi->next = hi->this->next; |
| return hi; |
| } |
| |
| AXIS2_DECLARE(axis2_hash_index_t*) |
| axis2_hash_first (axis2_hash_t *ht, axis2_env_t **environment) |
| { |
| axis2_hash_index_t *hi; |
| if (environment && *environment) |
| hi = AXIS2_MALLOC ((*environment)->allocator, sizeof (*hi)); |
| else |
| hi = &ht->iterator; |
| |
| hi->ht = ht; |
| hi->index = 0; |
| hi->this = NULL; |
| hi->next = NULL; |
| return axis2_hash_next (environment, hi); |
| } |
| |
| AXIS2_DECLARE(void) |
| axis2_hash_this (axis2_hash_index_t *hi, |
| const void **key, axis2_ssize_t *klen, void **val) |
| { |
| if (key) |
| *key = hi->this->key; |
| if (klen) |
| *klen = hi->this->klen; |
| if (val) |
| *val = (void *) hi->this->val; |
| } |
| |
| |
| /* |
| * Expanding a hash table |
| */ |
| |
| static void |
| expand_array (axis2_hash_t * ht) |
| { |
| axis2_hash_index_t *hi; |
| axis2_env_t **env = NULL; |
| |
| axis2_hash_entry_t **new_array; |
| unsigned int new_max; |
| |
| new_max = ht->max * 2 + 1; |
| new_array = alloc_array (ht, new_max); |
| for (hi = axis2_hash_first (ht, NULL); hi; |
| hi = axis2_hash_next (NULL, hi)) |
| { |
| unsigned int i = hi->this->hash & new_max; |
| hi->this->next = new_array[i]; |
| new_array[i] = hi->this; |
| } |
| ht->array = new_array; |
| ht->max = new_max; |
| } |
| |
| unsigned int |
| axis2_hashfunc_default (const char *char_key, axis2_ssize_t * klen) |
| { |
| unsigned int hash = 0; |
| const unsigned char *key = (const unsigned char *) char_key; |
| const unsigned char *p; |
| axis2_ssize_t i; |
| |
| /* |
| * This is the popular `times 33' hash algorithm which is used by |
| * perl and also appears in Berkeley DB. This is one of the best |
| * known hash functions for strings because it is both computed |
| * very fast and distributes very well. |
| * |
| * The originator may be Dan Bernstein but the code in Berkeley DB |
| * cites Chris Torek as the source. The best citation I have found |
| * is "Chris Torek, Hash function for text in C, Usenet message |
| * <27038@mimsy.umd.edu> in comp.lang.c , October, 1990." in Rich |
| * Salz's USENIX 1992 paper about INN which can be found at |
| * <http://citeseer.nj.nec.com/salz92internetnews.html>. |
| * |
| * The magic of number 33, i.e. why it works better than many other |
| * constants, prime or not, has never been adequately explained by |
| * anyone. So I try an explanation: if one experimentally tests all |
| * multipliers between 1 and 256 (as I did while writing a low-level |
| * data structure library some time ago) one detects that even |
| * numbers are not useable at all. The remaining 128 odd numbers |
| * (except for the number 1) work more or less all equally well. |
| * They all distribute in an acceptable way and this way fill a hash |
| * table with an average percent of approx. 86%. |
| * |
| * If one compares the chi^2 values of the variants (see |
| * Bob Jenkins ``Hashing Frequently Asked Questions'' at |
| * http://burtleburtle.net/bob/hash/hashfaq.html for a description |
| * of chi^2), the number 33 not even has the best value. But the |
| * number 33 and a few other equally good numbers like 17, 31, 63, |
| * 127 and 129 have nevertheless a great advantage to the remaining |
| * numbers in the large set of possible multipliers: their multiply |
| * op can be replaced by a faster op based on just one |
| * shift plus either a single addition or subtraction op. And |
| * because a hash function has to both distribute good _and_ has to |
| * be very fast to compute, those few numbers should be preferred. |
| * |
| * -- Ralf S. Engelschall <rse@engelschall.com> |
| */ |
| |
| if (*klen == AXIS2_HASH_KEY_STRING) |
| { |
| for (p = key; *p; p++) |
| { |
| hash = hash * 33 + *p; |
| } |
| *klen = p - key; |
| } |
| else |
| { |
| for (p = key, i = *klen; i; i--, p++) |
| { |
| hash = hash * 33 + *p; |
| } |
| } |
| |
| return hash; |
| } |
| |
| |
| /* |
| * This is where we keep the details of the hash function and control |
| * the maximum collision rate. |
| * |
| * If val is non-NULL it creates and initializes a new hash entry if |
| * there isn't already one there; it returns an updatable pointer so |
| * that hash entries can be removed. |
| */ |
| |
| static axis2_hash_entry_t ** |
| find_entry (axis2_hash_t * ht, |
| const void *key, axis2_ssize_t klen, const void *val) |
| { |
| axis2_hash_entry_t **hep, *he; |
| unsigned int hash; |
| |
| hash = ht->hash_func (key, &klen); |
| |
| /* scan linked list */ |
| for (hep = &ht->array[hash & ht->max], he = *hep; |
| he; hep = &he->next, he = *hep) |
| { |
| if (he->hash == hash |
| && he->klen == klen && memcmp (he->key, key, klen) == 0) |
| break; |
| } |
| if (he || !val) |
| return hep; |
| |
| /* add a new entry for non-NULL values */ |
| if ((he = ht->free) != NULL) |
| ht->free = he->next; |
| else |
| he = AXIS2_MALLOC (ht->environment->allocator, sizeof (*he)); |
| he->next = NULL; |
| he->hash = hash; |
| he->key = key; |
| he->klen = klen; |
| he->val = val; |
| *hep = he; |
| ht->count++; |
| return hep; |
| } |
| |
| AXIS2_DECLARE(axis2_hash_t*) |
| axis2_hash_copy (const axis2_hash_t *orig, axis2_env_t **environment) |
| { |
| axis2_hash_t *ht; |
| axis2_hash_entry_t *new_vals; |
| unsigned int i, j; |
| |
| AXIS2_ENV_CHECK(environment, NULL); |
| |
| ht = AXIS2_MALLOC ((*environment)->allocator, sizeof (axis2_hash_t) + |
| sizeof (*ht->array) * (orig->max + 1) + |
| sizeof (axis2_hash_entry_t) * orig->count); |
| ht->environment = (*environment); |
| ht->free = NULL; |
| ht->count = orig->count; |
| ht->max = orig->max; |
| ht->hash_func = orig->hash_func; |
| ht->array = (axis2_hash_entry_t **) ((char *) ht + sizeof (axis2_hash_t)); |
| |
| new_vals = (axis2_hash_entry_t *) ((char *) (ht) + sizeof (axis2_hash_t) + |
| sizeof (*ht->array) * (orig->max + 1)); |
| j = 0; |
| for (i = 0; i <= ht->max; i++) |
| { |
| axis2_hash_entry_t **new_entry = &(ht->array[i]); |
| axis2_hash_entry_t *orig_entry = orig->array[i]; |
| while (orig_entry) |
| { |
| *new_entry = &new_vals[j++]; |
| (*new_entry)->hash = orig_entry->hash; |
| (*new_entry)->key = orig_entry->key; |
| (*new_entry)->klen = orig_entry->klen; |
| (*new_entry)->val = orig_entry->val; |
| new_entry = &((*new_entry)->next); |
| orig_entry = orig_entry->next; |
| } |
| *new_entry = NULL; |
| } |
| return ht; |
| } |
| |
| AXIS2_DECLARE(void*) |
| axis2_hash_get (axis2_hash_t *ht, const void *key, axis2_ssize_t klen) |
| { |
| axis2_hash_entry_t *he; |
| he = *find_entry (ht, key, klen, NULL); |
| if (he) |
| return (void *) he->val; |
| else |
| return NULL; |
| } |
| |
| AXIS2_DECLARE(void) |
| axis2_hash_set (axis2_hash_t *ht, |
| const void *key, axis2_ssize_t klen, const void *val) |
| { |
| axis2_hash_entry_t **hep; |
| hep = find_entry (ht, key, klen, val); |
| if (*hep) |
| { |
| if (!val) |
| { |
| /* delete entry */ |
| axis2_hash_entry_t *old = *hep; |
| *hep = (*hep)->next; |
| old->next = ht->free; |
| ht->free = old; |
| --ht->count; |
| } |
| else |
| { |
| /* replace entry */ |
| (*hep)->val = val; |
| /* check that the collision rate isn't too high */ |
| if (ht->count > ht->max) |
| { |
| expand_array (ht); |
| } |
| } |
| } |
| /* else key not present and val==NULL */ |
| } |
| |
| AXIS2_DECLARE( unsigned int ) |
| axis2_hash_count (axis2_hash_t * ht) |
| { |
| return ht->count; |
| } |
| |
| AXIS2_DECLARE(axis2_hash_t*) |
| axis2_hash_overlay (const axis2_hash_t *overlay, axis2_env_t **environment |
| , const axis2_hash_t * base) |
| { |
| AXIS2_ENV_CHECK(environment, NULL); |
| return axis2_hash_merge (overlay, environment, base, NULL, NULL); |
| } |
| |
| AXIS2_DECLARE(axis2_hash_t*) |
| axis2_hash_merge (const axis2_hash_t *overlay, axis2_env_t **environment |
| , const axis2_hash_t * base, void *(*merger) (axis2_env_t * environment |
| , const void *key, axis2_ssize_t klen, const void *h1_val |
| , const void *h2_val, const void *data), const void *data) |
| { |
| axis2_hash_t *res; |
| axis2_hash_entry_t *new_vals = NULL; |
| axis2_hash_entry_t *iter; |
| axis2_hash_entry_t *ent; |
| unsigned int i, j, k; |
| AXIS2_ENV_CHECK(environment, NULL); |
| |
| #if AXIS2_POOL_DEBUG |
| /* we don't copy keys and values, so it's necessary that |
| * overlay->a.environment and base->a.environment have a life span at least |
| * as long as p |
| */ |
| if (!axis2_environment_is_ancestor (overlay->environment, p)) |
| { |
| fprintf (stderr, |
| "axis2_hash_merge: overlay's environment is not an ancestor of p\n"); |
| abort (); |
| } |
| if (!axis2_environment_is_ancestor (base->environment, p)) |
| { |
| fprintf (stderr, |
| "axis2_hash_merge: base's environment is not an ancestor of p\n"); |
| abort (); |
| } |
| #endif |
| |
| res = AXIS2_MALLOC ((*environment)->allocator, sizeof (axis2_hash_t)); |
| res->environment = *environment; |
| res->free = NULL; |
| res->hash_func = base->hash_func; |
| res->count = base->count; |
| res->max = (overlay->max > base->max) ? overlay->max : base->max; |
| if (base->count + overlay->count > res->max) |
| { |
| res->max = res->max * 2 + 1; |
| } |
| res->array = alloc_array (res, res->max); |
| if (base->count + overlay->count) |
| { |
| new_vals = |
| AXIS2_MALLOC ((*environment)->allocator, |
| sizeof (axis2_hash_entry_t) * (base->count + |
| overlay->count)); |
| } |
| j = 0; |
| for (k = 0; k <= base->max; k++) |
| { |
| for (iter = base->array[k]; iter; iter = iter->next) |
| { |
| i = iter->hash & res->max; |
| new_vals[j].klen = iter->klen; |
| new_vals[j].key = iter->key; |
| new_vals[j].val = iter->val; |
| new_vals[j].hash = iter->hash; |
| new_vals[j].next = res->array[i]; |
| res->array[i] = &new_vals[j]; |
| j++; |
| } |
| } |
| |
| for (k = 0; k <= overlay->max; k++) |
| { |
| for (iter = overlay->array[k]; iter; iter = iter->next) |
| { |
| i = iter->hash & res->max; |
| for (ent = res->array[i]; ent; ent = ent->next) |
| { |
| if ((ent->klen == iter->klen) && |
| (memcmp (ent->key, iter->key, iter->klen) == 0)) |
| { |
| if (merger) |
| { |
| ent->val = |
| (*merger) ((*environment), iter->key, iter->klen, |
| iter->val, ent->val, data); |
| } |
| else |
| { |
| ent->val = iter->val; |
| } |
| break; |
| } |
| } |
| if (!ent) |
| { |
| new_vals[j].klen = iter->klen; |
| new_vals[j].key = iter->key; |
| new_vals[j].val = iter->val; |
| new_vals[j].hash = iter->hash; |
| new_vals[j].next = res->array[i]; |
| res->array[i] = &new_vals[j]; |
| res->count++; |
| j++; |
| } |
| } |
| } |
| return res; |
| } |
| |
| static axis2_status_t |
| axis2_hash_entry_free (axis2_env_t **environment, axis2_hash_entry_t *hash_entry) |
| { |
| AXIS2_ENV_CHECK(environment, AXIS2_FAILURE); |
| if (!hash_entry) |
| return AXIS2_FAILURE; |
| if (hash_entry->next) |
| { |
| axis2_hash_entry_free (environment, hash_entry->next); |
| } |
| AXIS2_FREE ((*environment)->allocator, hash_entry); |
| return AXIS2_SUCCESS; |
| } |
| |
| AXIS2_DECLARE(axis2_status_t) |
| axis2_hash_free (axis2_hash_t *ht, axis2_env_t** environment) |
| { |
| int i =0; |
| AXIS2_ENV_CHECK(environment, AXIS2_FAILURE); |
| if (ht) |
| { |
| for(i = 0;i <ht->max; i++) |
| { |
| if(ht->array[i]) |
| { |
| AXIS2_FREE((*environment)->allocator, ht->array[i]); |
| } |
| } |
| AXIS2_FREE((*environment)->allocator, (ht->array)); |
| AXIS2_FREE ((*environment)->allocator, ht); |
| return AXIS2_SUCCESS; |
| } |
| return AXIS2_FAILURE; |
| } |