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      1 /**************************************************************************
      2  *
      3  * Copyright 2007 VMware, Inc.
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
     10  * distribute, sub license, and/or sell copies of the Software, and to
     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
     21  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
     22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
     23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28  /*
     29   * Authors:
     30   *   Zack Rusin <zackr (at) vmware.com>
     31   */
     32 
     33 #include "util/u_debug.h"
     34 #include "util/u_memory.h"
     35 
     36 #include "cso_hash.h"
     37 
     38 #ifndef MAX
     39 #define MAX(a, b) ((a > b) ? (a) : (b))
     40 #endif
     41 
     42 static const int MinNumBits = 4;
     43 
     44 static const unsigned char prime_deltas[] = {
     45    0,  0,  1,  3,  1,  5,  3,  3,  1,  9,  7,  5,  3,  9, 25,  3,
     46    1, 21,  3, 21,  7, 15,  9,  5,  3, 29, 15,  0,  0,  0,  0,  0
     47 };
     48 
     49 static int primeForNumBits(int numBits)
     50 {
     51    return (1 << numBits) + prime_deltas[numBits];
     52 }
     53 
     54 /*
     55     Returns the smallest integer n such that
     56     primeForNumBits(n) >= hint.
     57 */
     58 static int countBits(int hint)
     59 {
     60    int numBits = 0;
     61    int bits = hint;
     62 
     63    while (bits > 1) {
     64       bits >>= 1;
     65       numBits++;
     66    }
     67 
     68    if (numBits >= (int)sizeof(prime_deltas)) {
     69       numBits = sizeof(prime_deltas) - 1;
     70    } else if (primeForNumBits(numBits) < hint) {
     71       ++numBits;
     72    }
     73    return numBits;
     74 }
     75 
     76 struct cso_node {
     77    struct cso_node *next;
     78    unsigned key;
     79    void *value;
     80 };
     81 
     82 struct cso_hash_data {
     83    struct cso_node *fakeNext;
     84    struct cso_node **buckets;
     85    int size;
     86    int nodeSize;
     87    short userNumBits;
     88    short numBits;
     89    int numBuckets;
     90 };
     91 
     92 struct cso_hash {
     93    union {
     94       struct cso_hash_data *d;
     95       struct cso_node      *e;
     96    } data;
     97 };
     98 
     99 static void *cso_data_allocate_node(struct cso_hash_data *hash)
    100 {
    101    return MALLOC(hash->nodeSize);
    102 }
    103 
    104 static void cso_free_node(struct cso_node *node)
    105 {
    106    FREE(node);
    107 }
    108 
    109 static struct cso_node *
    110 cso_hash_create_node(struct cso_hash *hash,
    111                       unsigned akey, void *avalue,
    112                       struct cso_node **anextNode)
    113 {
    114    struct cso_node *node = cso_data_allocate_node(hash->data.d);
    115 
    116    if (!node)
    117       return NULL;
    118 
    119    node->key = akey;
    120    node->value = avalue;
    121 
    122    node->next = (struct cso_node*)(*anextNode);
    123    *anextNode = node;
    124    ++hash->data.d->size;
    125    return node;
    126 }
    127 
    128 static void cso_data_rehash(struct cso_hash_data *hash, int hint)
    129 {
    130    if (hint < 0) {
    131       hint = countBits(-hint);
    132       if (hint < MinNumBits)
    133          hint = MinNumBits;
    134       hash->userNumBits = (short)hint;
    135       while (primeForNumBits(hint) < (hash->size >> 1))
    136          ++hint;
    137    } else if (hint < MinNumBits) {
    138       hint = MinNumBits;
    139    }
    140 
    141    if (hash->numBits != hint) {
    142       struct cso_node *e = (struct cso_node *)(hash);
    143       struct cso_node **oldBuckets = hash->buckets;
    144       int oldNumBuckets = hash->numBuckets;
    145       int  i = 0;
    146 
    147       hash->numBits = (short)hint;
    148       hash->numBuckets = primeForNumBits(hint);
    149       hash->buckets = MALLOC(sizeof(struct cso_node*) * hash->numBuckets);
    150       for (i = 0; i < hash->numBuckets; ++i)
    151          hash->buckets[i] = e;
    152 
    153       for (i = 0; i < oldNumBuckets; ++i) {
    154          struct cso_node *firstNode = oldBuckets[i];
    155          while (firstNode != e) {
    156             unsigned h = firstNode->key;
    157             struct cso_node *lastNode = firstNode;
    158             struct cso_node *afterLastNode;
    159             struct cso_node **beforeFirstNode;
    160 
    161             while (lastNode->next != e && lastNode->next->key == h)
    162                lastNode = lastNode->next;
    163 
    164             afterLastNode = lastNode->next;
    165             beforeFirstNode = &hash->buckets[h % hash->numBuckets];
    166             while (*beforeFirstNode != e)
    167                beforeFirstNode = &(*beforeFirstNode)->next;
    168             lastNode->next = *beforeFirstNode;
    169             *beforeFirstNode = firstNode;
    170             firstNode = afterLastNode;
    171          }
    172       }
    173       FREE(oldBuckets);
    174    }
    175 }
    176 
    177 static void cso_data_might_grow(struct cso_hash_data *hash)
    178 {
    179    if (hash->size >= hash->numBuckets)
    180       cso_data_rehash(hash, hash->numBits + 1);
    181 }
    182 
    183 static void cso_data_has_shrunk(struct cso_hash_data *hash)
    184 {
    185    if (hash->size <= (hash->numBuckets >> 3) &&
    186        hash->numBits > hash->userNumBits) {
    187       int max = MAX(hash->numBits-2, hash->userNumBits);
    188       cso_data_rehash(hash,  max);
    189    }
    190 }
    191 
    192 static struct cso_node *cso_data_first_node(struct cso_hash_data *hash)
    193 {
    194    struct cso_node *e = (struct cso_node *)(hash);
    195    struct cso_node **bucket = hash->buckets;
    196    int n = hash->numBuckets;
    197    while (n--) {
    198       if (*bucket != e)
    199          return *bucket;
    200       ++bucket;
    201    }
    202    return e;
    203 }
    204 
    205 static struct cso_node **cso_hash_find_node(struct cso_hash *hash, unsigned akey)
    206 {
    207    struct cso_node **node;
    208 
    209    if (hash->data.d->numBuckets) {
    210       node = (struct cso_node **)(&hash->data.d->buckets[akey % hash->data.d->numBuckets]);
    211       assert(*node == hash->data.e || (*node)->next);
    212       while (*node != hash->data.e && (*node)->key != akey)
    213          node = &(*node)->next;
    214    } else {
    215       node = (struct cso_node **)((const struct cso_node * const *)(&hash->data.e));
    216    }
    217    return node;
    218 }
    219 
    220 struct cso_hash_iter cso_hash_insert(struct cso_hash *hash,
    221                                        unsigned key, void *data)
    222 {
    223    cso_data_might_grow(hash->data.d);
    224 
    225    {
    226       struct cso_node **nextNode = cso_hash_find_node(hash, key);
    227       struct cso_node *node = cso_hash_create_node(hash, key, data, nextNode);
    228       if (!node) {
    229          struct cso_hash_iter null_iter = {hash, 0};
    230          return null_iter;
    231       }
    232 
    233       {
    234          struct cso_hash_iter iter = {hash, node};
    235          return iter;
    236       }
    237    }
    238 }
    239 
    240 struct cso_hash * cso_hash_create(void)
    241 {
    242    struct cso_hash *hash = MALLOC_STRUCT(cso_hash);
    243    if (!hash)
    244       return NULL;
    245 
    246    hash->data.d = MALLOC_STRUCT(cso_hash_data);
    247    if (!hash->data.d) {
    248       FREE(hash);
    249       return NULL;
    250    }
    251 
    252    hash->data.d->fakeNext = 0;
    253    hash->data.d->buckets = 0;
    254    hash->data.d->size = 0;
    255    hash->data.d->nodeSize = sizeof(struct cso_node);
    256    hash->data.d->userNumBits = (short)MinNumBits;
    257    hash->data.d->numBits = 0;
    258    hash->data.d->numBuckets = 0;
    259 
    260    return hash;
    261 }
    262 
    263 void cso_hash_delete(struct cso_hash *hash)
    264 {
    265    struct cso_node *e_for_x = (struct cso_node *)(hash->data.d);
    266    struct cso_node **bucket = (struct cso_node **)(hash->data.d->buckets);
    267    int n = hash->data.d->numBuckets;
    268    while (n--) {
    269       struct cso_node *cur = *bucket++;
    270       while (cur != e_for_x) {
    271          struct cso_node *next = cur->next;
    272          cso_free_node(cur);
    273          cur = next;
    274       }
    275    }
    276    FREE(hash->data.d->buckets);
    277    FREE(hash->data.d);
    278    FREE(hash);
    279 }
    280 
    281 struct cso_hash_iter cso_hash_find(struct cso_hash *hash,
    282                                      unsigned key)
    283 {
    284    struct cso_node **nextNode = cso_hash_find_node(hash, key);
    285    struct cso_hash_iter iter = {hash, *nextNode};
    286    return iter;
    287 }
    288 
    289 unsigned cso_hash_iter_key(struct cso_hash_iter iter)
    290 {
    291    if (!iter.node || iter.hash->data.e == iter.node)
    292       return 0;
    293    return iter.node->key;
    294 }
    295 
    296 void * cso_hash_iter_data(struct cso_hash_iter iter)
    297 {
    298    if (!iter.node || iter.hash->data.e == iter.node)
    299       return 0;
    300    return iter.node->value;
    301 }
    302 
    303 static struct cso_node *cso_hash_data_next(struct cso_node *node)
    304 {
    305    union {
    306       struct cso_node *next;
    307       struct cso_node *e;
    308       struct cso_hash_data *d;
    309    } a;
    310    int start;
    311    struct cso_node **bucket;
    312    int n;
    313 
    314    a.next = node->next;
    315    if (!a.next) {
    316       debug_printf("iterating beyond the last element\n");
    317       return 0;
    318    }
    319    if (a.next->next)
    320       return a.next;
    321 
    322    start = (node->key % a.d->numBuckets) + 1;
    323    bucket = a.d->buckets + start;
    324    n = a.d->numBuckets - start;
    325    while (n--) {
    326       if (*bucket != a.e)
    327          return *bucket;
    328       ++bucket;
    329    }
    330    return a.e;
    331 }
    332 
    333 
    334 static struct cso_node *cso_hash_data_prev(struct cso_node *node)
    335 {
    336    union {
    337       struct cso_node *e;
    338       struct cso_hash_data *d;
    339    } a;
    340    int start;
    341    struct cso_node *sentinel;
    342    struct cso_node **bucket;
    343 
    344    a.e = node;
    345    while (a.e->next)
    346       a.e = a.e->next;
    347 
    348    if (node == a.e)
    349       start = a.d->numBuckets - 1;
    350    else
    351       start = node->key % a.d->numBuckets;
    352 
    353    sentinel = node;
    354    bucket = a.d->buckets + start;
    355    while (start >= 0) {
    356       if (*bucket != sentinel) {
    357          struct cso_node *prev = *bucket;
    358          while (prev->next != sentinel)
    359             prev = prev->next;
    360          return prev;
    361       }
    362 
    363       sentinel = a.e;
    364       --bucket;
    365       --start;
    366    }
    367    debug_printf("iterating backward beyond first element\n");
    368    return a.e;
    369 }
    370 
    371 struct cso_hash_iter cso_hash_iter_next(struct cso_hash_iter iter)
    372 {
    373    struct cso_hash_iter next = {iter.hash, cso_hash_data_next(iter.node)};
    374    return next;
    375 }
    376 
    377 int cso_hash_iter_is_null(struct cso_hash_iter iter)
    378 {
    379    if (!iter.node || iter.node == iter.hash->data.e)
    380       return 1;
    381    return 0;
    382 }
    383 
    384 void * cso_hash_take(struct cso_hash *hash,
    385                       unsigned akey)
    386 {
    387    struct cso_node **node = cso_hash_find_node(hash, akey);
    388    if (*node != hash->data.e) {
    389       void *t = (*node)->value;
    390       struct cso_node *next = (*node)->next;
    391       cso_free_node(*node);
    392       *node = next;
    393       --hash->data.d->size;
    394       cso_data_has_shrunk(hash->data.d);
    395       return t;
    396    }
    397    return 0;
    398 }
    399 
    400 struct cso_hash_iter cso_hash_iter_prev(struct cso_hash_iter iter)
    401 {
    402    struct cso_hash_iter prev = {iter.hash,
    403                                  cso_hash_data_prev(iter.node)};
    404    return prev;
    405 }
    406 
    407 struct cso_hash_iter cso_hash_first_node(struct cso_hash *hash)
    408 {
    409    struct cso_hash_iter iter = {hash, cso_data_first_node(hash->data.d)};
    410    return iter;
    411 }
    412 
    413 int cso_hash_size(struct cso_hash *hash)
    414 {
    415    return hash->data.d->size;
    416 }
    417 
    418 struct cso_hash_iter cso_hash_erase(struct cso_hash *hash, struct cso_hash_iter iter)
    419 {
    420    struct cso_hash_iter ret = iter;
    421    struct cso_node *node = iter.node;
    422    struct cso_node **node_ptr;
    423 
    424    if (node == hash->data.e)
    425       return iter;
    426 
    427    ret = cso_hash_iter_next(ret);
    428    node_ptr = (struct cso_node**)(&hash->data.d->buckets[node->key % hash->data.d->numBuckets]);
    429    while (*node_ptr != node)
    430       node_ptr = &(*node_ptr)->next;
    431    *node_ptr = node->next;
    432    cso_free_node(node);
    433    --hash->data.d->size;
    434    return ret;
    435 }
    436 
    437 boolean cso_hash_contains(struct cso_hash *hash, unsigned key)
    438 {
    439    struct cso_node **node = cso_hash_find_node(hash, key);
    440    return (*node != hash->data.e);
    441 }
    442