/* An implementation of hash tables: * Copyright(C) 2000-2001 Salvatore Sanfilippo * * TODO: * o ht_copy() to copy an element between hash tables * o ht_dup() to duplicate an entire hash table * o ht_merge() to add the content of one hash table to another * o disk operations, the ability to save an hashtable from the * memory to the disk and the reverse operation. * * LICENSE * ------- * * Copyright (c) 2000-2001 Salvatore Sanfilippo * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * Products derived from the Software may not be called with the original * name of the Software, the name of the Software and the name of the authors * may not be used to endorse or promote products derived from the Software * without prior written permission from all the authors of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include #include #include #include #include "aht.h" /* The special ht_free_element pointer is used to mark * a freed element in the hash table (note that the elements * neven used are just NULL pointers) */ static struct ht_ele *ht_free_element = (void*) -1; static const unsigned int small_primes[] = { /* 2 is eliminated by trying only odd numbers. */ 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987, 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053, 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129, 2131, 2137, 2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213, 2221, 2237, 2239, 2243, 2251, 2267, 2269, 2273, 2281, 2287, 2293, 2297, 2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357, 2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423, 2437, 2441, 2447, 2459, 2467, 2473, 2477, 2503, 2521, 2531, 2539, 2543, 2549, 2551, 2557, 2579, 2591, 2593, 2609, 2617, 2621, 2633, 2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687, 2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729, 2731, 2741, 2749, 2753, 2767, 2777, 2789, 2791, 2797, 2801, 2803, 2819, 2833, 2837, 2843, 2851, 2857, 2861, 2879, 2887, 2897, 2903, 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971, 2999, 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079, 3083, 3089, 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, 3187, 3191, 3203, 3209, 3217, 3221, 3229, 3251, 3253, 3257, 3259, 3271, 3299, 3301, 3307, 3313, 3319, 3323, 3329, 3331, 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391, 3407, 3413, 3433, 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511, 3517, 3527, 3529, 3533, 3539, 3541, 3547, 3557, 3559, 3571, 3581, 3583, 3593, 3607, 3613, 3617, 3623, 3631, 3637, 3643, 3659, 3671, 3673, 3677, 3691, 3697, 3701, 3709, 3719, 3727, 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797, 3803, 3821, 3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881, 3889, 3907, 3911, 3917, 3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989, 4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051, 4057, 4073, 4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139, 4153, 4157, 4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243, 4253, 4259, 4261, 4271, 4273, 4283, 4289, 4297, 4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391, 4397, 4409, 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481, 4483, 4493, 4507, 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583, 4591, 4597, 4603, 4621, 4637, 4639, 4643, 4649, 4651, 4657, 4663, 4673, 4679, 4691, 4703, 4721, 4723, 4729, 4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799, 4801, 4813, 4817, 4831, 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931, 4933, 4937, 4943, 4951, 4957, 4967, 4969, 4973, 4987, 4993, 4999, 5003, 5009, 5011, 5021, 5023, 5039, 5051, 5059, 5077, 5081, 5087, 5099, 5101, 5107, 5113, 5119, 5147, 5153, 5167, 5171, 5179, 5189, 5197, 5209, 5227, 5231, 5233, 5237, 5261, 5273, 5279, 5281, 5297, 5303, 5309, 5323, 5333, 5347, 5351, 5381, 5387, 5393, 5399, 5407, 5413, 5417, 5419, 5431, 5437, 5441, 5443, 5449, 5471, 5477, 5479, 5483, 5501, 5503, 5507, 5519, 5521, 5527, 5531, 5557, 5563, 5569, 5573, 5581, 5591, 5623, 5639, 5641, 5647, 5651, 5653, 5657, 5659, 5669, 5683, 5689, 5693, 5701, 5711, 5717, 5737, 5741, 5743, 5749, 5779, 5783, 5791, 5801, 5807, 5813, 5821, 5827, 5839, 5843, 5849, 5851, 5857, 5861, 5867, 5869, 5879, 5881, 5897, 5903, 5923, 5927, 5939, 5953, 5981, 5987, 6007, 6011, 6029, 6037, 6043, 6047, 6053, 6067, 6073, 6079, 6089, 6091, 6101, 6113, 6121, 6131, 6133, 6143, 6151, 6163, 6173, 6197, 6199, 6203, 6211, 6217, 6221, 6229, 6247, 6257, 6263, 6269, 6271, 6277, 6287, 6299, 6301, 6311, 6317, 6323, 6329, 6337, 6343, 6353, 6359, 6361, 6367, 6373, 6379, 6389, 6397, 6421, 6427, 6449, 6451, 6469, 6473, 6481, 6491, 6521, 6529, 6547, 6551, 6553, 6563, 6569, 6571, 6577, 6581, 6599, 6607, 6619, 6637, 6653, 6659, 6661, 6673, 6679, 6689, 6691, 6701, 6703, 6709, 6719, 6733, 6737, 6761, 6763, 6779, 6781, 6791, 6793, 6803, 6823, 6827, 6829, 6833, 6841, 6857, 6863, 6869, 6871, 6883, 6899, 6907, 6911, 6917, 6947, 6949, 6959, 6961, 6967, 6971, 6977, 6983, 6991, 6997, 7001, 7013, 7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103, 7109, 7121, 7127, 7129, 7151, 7159, 7177, 7187, 7193, 7207, 7211, 7213, 7219, 7229, 7237, 7243, 7247, 7253, 7283, 7297, 7307, 7309, 7321, 7331, 7333, 7349, 7351, 7369, 7393, 7411, 7417, 7433, 7451, 7457, 7459, 7477, 7481, 7487, 7489, 7499, 7507, 7517, 7523, 7529, 7537, 7541, 7547, 7549, 7559, 7561, 7573, 7577, 7583, 7589, 7591, 7603, 7607, 7621, 7639, 7643, 7649, 7669, 7673, 7681, 7687, 7691, 7699, 7703, 7717, 7723, 7727, 7741, 7753, 7757, 7759, 7789, 7793, 7817, 7823, 7829, 7841, 7853, 7867, 7873, 7877, 7879, 7883, 7901, 7907, 7919, 7927, 7933, 7937, 7949, 7951, 7963, 7993, 8009, 8011, 8017, 8039, 8053, 8059, 8069, 8081, 8087, 8089, 8093, 8101, 8111, 8117, 8123, 8147, 8161, 8167, 8171, 8179, 8191, 0}; /* All the numbers congruent to 1, 7, 11, 13, 17, * 19, 23, and 29 modulo 30 are a superset of * all the prime numbers: * More info at: * http://www.utm.edu/research/primes/glossary/WheelFactorization.html * * Starting from 8191 that's the last prime in the * small_primes list we must add: */ static unsigned add[] = {6, 4, 2, 4, 2, 4, 6, 2}; /* The djb hash function, that's under public domain */ u_int32_t djb_hash(unsigned char *buf, size_t len) { int i; u_int32_t h = 5381; for (i = 0; i < len; i++) h = (h + (h << 5)) ^ buf[i]; return h; } /* My own hash function. It shows a good distribution * with strings, but it's quite slower due to the presence * of the multiplication. You may use it as a second hash * function in double hashing if the key is a string * (otherwise it sucks). It's based on the concept of * mixing different algebrical groups */ u_int32_t alt_hashf(unsigned char *buf, size_t len) { int i; u_int32_t h = 5381; for (i = 0; i < len; i++) { if (i & 1) h *= buf[i]; else h += buf[i]; } return h; } /* This functions are used to generate prime numbers: to * make the hash table the nearest prime number to a power of 2 * can avoid some problem related to bad distribution of the hash * functions. * * The following function try to divide the number to the small_primes * list, then try to use the 'wheel factorization'. * We should stop to try at the square root of the number * but I want not link against the math lib, so the function * stops when the divisor reaches n/2 */ int isprime(int n) { int i = 0; int p, limit = n/2; if ((n & 1) == 0) return 0; while ((p = small_primes[i++]) != 0 && p < n) { if ((n % p) == 0) return 0; } i = 0; p = 8191; /* the last prime in the small_primes table */ p += add[i++]; while (p < limit) { if ((n % p) == 0) return 0; p += add[i]; i = (i+1)%8; } return 1; } /* Return the littlest prime number major or equal to n */ int next_prime(int n) { while (isprime(n) == 0) n++; return n; } /* Initialize the hash table */ void ht_init(struct hashtable *t) { t->table = NULL; t->size = 0; t->used = 0; t->collisions = 0; t->hashf[0] = djb_hash; /* Our default hash function */ t->hashf[1] = t->hashf[2] = NULL; } /* Expand the hash table if needed */ int ht_expand_if_needed(struct hashtable *t) { int ret; /* If the hash table is empty expand it to the intial size, * if the table is half-full redobule its size. */ if (t->size == 0) { ret = ht_expand(t, HT_INITIAL_SIZE); if (ret != HT_OK) return ret; } else if (t->size <= (t->used << 1)) { ret = ht_expand(t, t->size << 1); if (ret != HT_OK) return ret; } return HT_OK; } /* Resize the table to the minimal size that contains all the elements */ int ht_resize(struct hashtable *t) { int minimal = (t->used * 2)+1; if (minimal < HT_INITIAL_SIZE) minimal = HT_INITIAL_SIZE; return ht_expand(t, minimal); } /* Move an element accross hash tables */ int ht_move(struct hashtable *orig, struct hashtable *dest, unsigned int index) { int ret; unsigned int new_index; /* If the element isn't in the table ht_search will store * the index of the free ht_ele in the integer pointer by *index */ ret = ht_search(dest, orig->table[index]->key, orig->table[index]->keysize, &new_index, NULL); if (ret == HT_FOUND) return HT_BUSY; else if (ret != HT_NOTFOUND) /* then report the error */ return ret; /* Move the element */ dest->table[new_index] = orig->table[index]; orig->table[index] = ht_free_element; orig->used--; dest->used++; return HT_OK; } /* Expand or create the hashtable structures */ int ht_expand(struct hashtable *t, size_t size) { struct hashtable n; /* the new hashtable */ unsigned int realsize = next_prime(size), i; int ret, j; ht_init(&n); n.size = realsize; n.table = malloc(realsize*sizeof(struct ht_ele*)); if (n.table == NULL) return HT_NOMEM; /* Copy the hash functions pointers */ for (j = 0; j < HT_FUNCTIONS; j++) n.hashf[j] = t->hashf[j]; /* Initialize all the pointers to NULL */ memset(n.table, 0, realsize*sizeof(struct ht_ele*)); /* Copy all the elements from the old to the new table: * note that if the old hash table is empty t->size is zero, * so ht_expand() acts like an ht_create() */ for (i = 0; i < t->size && t->used > 0; i++) { if (t->table[i] != NULL && t->table[i] != ht_free_element) { /* ht_move is faster than ht_add() + ht_free() */ ret = ht_move(t, &n, i); /* If there aren't bugs ht_move() must return * only HT_OK or HT_NOMEM */ if (ret != HT_OK) { assert(ret == HT_NOMEM); ht_destroy(&n); return ret; } } } assert(t->used == 0); ht_destroy(t); /* Remap the new hashtable in the old */ *t = n; return HT_OK; } /* Add an element, discarding the old if the key exist */ int ht_replace(struct hashtable *t, void *key, size_t keysize, void *data, size_t datasize) { int ret; unsigned int index; /* Try to add the element */ ret = ht_add(t, key, keysize, data, datasize); if (ret == HT_OK || ret != HT_BUSY) return ret; /* It already exist, get the index */ ret = ht_search(t, key, keysize, NULL, &index); assert(ret == HT_FOUND); /* Remove the old */ ret = ht_free(t, index); assert(ret == HT_OK); /* And add the new */ return ht_add(t, key, keysize, data, datasize); } /* Add an element to the target hash table * allocating automatically dynamic memory */ int ht_add(struct hashtable *t, void *key, size_t keysize, void *data, size_t datasize) { int ret; char *mem; /* Copy the element in the dynamically allocated memory */ if (datasize > 0) { mem = malloc(datasize); if (mem == NULL) return HT_NOMEM; memcpy(mem, data, datasize); } else { mem = NULL; } ret = ht_add_generic(t, key, keysize, mem, datasize, ht_destructor_free); if (ret != HT_OK) free(mem); return ret; } /* Add an element to the target hash table */ int ht_add_generic(struct hashtable *t, void *key, size_t keysize, void *data, size_t datasize, void (*destructor) (void *obj, unsigned int size)) { int ret; unsigned int index; /* The key can't be zero length */ if (keysize == 0) return HT_INVALID; /* If the element isn't in the table ht_search() will store * the index of the free ht_ele in the integer pointer by *index */ ret = ht_search(t, key, keysize, &index, NULL); if (ret == HT_FOUND) return HT_BUSY; else if (ret != HT_NOTFOUND) /* then report the error */ return ret; /* Allocates the memory and stores key */ if ((t->table[index] = malloc(sizeof(struct ht_ele))) == NULL) return HT_NOMEM; if ((t->table[index]->key = malloc(keysize)) == NULL) { free(t->table[index]); return HT_NOMEM; } memcpy(t->table[index]->key, key, keysize); t->table[index]->keysize = keysize; /* Store the data pointer */ t->table[index]->data = data; t->table[index]->datasize = datasize; if (destructor != NULL) t->table[index]->destructor = destructor; else t->table[index]->destructor = ht_no_destructor; t->used++; return HT_OK; } /* Destroy an entire hash table */ int ht_destroy(struct hashtable *t) { unsigned int i; int ret; /* Free all the elements */ for (i = 0; i < t->size && t->used > 0; i++) { if (t->table[i] != NULL && t->table[i] != ht_free_element) { ret = ht_free(t, i); assert(ret == HT_OK); } } assert(t->used == 0); /* Free the table itself */ free(t->table); /* Re-initialize the table */ ht_init(t); return HT_OK; /* Actually ht_destroy never fails */ } #include /* Free an element in the hash table */ int ht_free(struct hashtable *t, unsigned int index) { if (index >= t->size) return HT_IOVERFLOW; /* Index overflow */ /* ht_free() calls against non-existent elements are ignored */ if (t->table[index] != NULL && t->table[index] != ht_free_element) { /* free the key data */ free(t->table[index]->key); /* call the destructor */ t->table[index]->destructor(t->table[index]->data, t->table[index]->datasize); /* free the element structure */ free(t->table[index]); /* mark the element as freed */ t->table[index] = ht_free_element; t->used--; } return HT_OK; } /* Return 1 if two keys matches */ int ht_key_match(void *key1, unsigned int size1, void *key2, unsigned int size2) { assert(size1 != 0 && size2 != 0); if (size1 != size2) return 0; if (memcmp(key1, key2, size1) == 0) return 1; return 0; } /* Search an element in the hash table: if the element does not exist * store the available index for the given key in *index */ int ht_search(struct hashtable *t, void *key, unsigned int keysize, unsigned int *avail_index, unsigned int *found_index) { int ret; u_int32_t h = 0; /* Just in the crazy case of NO hash functions */ unsigned int i; /* The user must leave at least one index pointer to NULL */ assert(!(avail_index != NULL && found_index != NULL)); /* Expand the hashtable if needed */ if (avail_index != NULL || t->size == 0) if ((ret = ht_expand_if_needed(t)) != HT_OK) return ret; /* Try using the hash functions */ for (i = 0; i < HT_FUNCTIONS && t->hashf[i] != NULL; i++) { h = t->hashf[i]((unsigned char *) key, keysize) % t->size; /* this handles the removed elements */ if (t->table[h] == ht_free_element) { if (avail_index) goto notfound; else continue; } if (t->table[h] == NULL) goto notfound; else if (ht_key_match(key, keysize, t->table[h]->key, t->table[h]->keysize)) goto found; t->collisions++; } /* Linear search */ for (i = 0; i < t->size; i++) { h = (h+1) % t->size; /* this handles the removed elements */ if (t->table[h] == ht_free_element) { if (avail_index) goto notfound; else continue; } if (t->table[h] == NULL) goto notfound; else if (ht_key_match(key, keysize, t->table[h]->key, t->table[h]->keysize)) goto found; t->collisions++; } /* The hash table can't be full in this implemenation, * it this happen there is a bug. We can reach this point * _only_ if we are searching for an element, not for an * empty slot in the table. So avail_index must be NULL */ assert(avail_index == NULL); return HT_NOTFOUND; found: if (found_index != NULL) *found_index = h; return HT_FOUND; notfound: if (avail_index != NULL) *avail_index = h; return HT_NOTFOUND; } /* The default destructor */ void ht_destructor_free(void *obj, unsigned int size) { free(obj); } /* the NULL destructor */ void ht_no_destructor(void *obj, unsigned int size) { } /* This function is used to run all the hash table, * it returns: * 1 if the element with the given index is valid * 0 if the element with the given index is empty or marked free * -1 if the element if out of the range */ int ht_get_byindex(struct hashtable *t, unsigned int index, struct ht_ele **e) { if (index >= t->size) return -1; if (t->table[index] == NULL || t->table[index] == ht_free_element) return 0; *e = t->table[index]; return 1; }