ucx: src/hash_map.c@d566bd3e6af8

     1 /*

     2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

     3  *

     4  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.

     5  *

     6  * Redistribution and use in source and binary forms, with or without

     7  * modification, are permitted provided that the following conditions are met:

     8  *

     9  *   1. Redistributions of source code must retain the above copyright

    10  *      notice, this list of conditions and the following disclaimer.

    11  *

    12  *   2. Redistributions in binary form must reproduce the above copyright

    13  *      notice, this list of conditions and the following disclaimer in the

    14  *      documentation and/or other materials provided with the distribution.

    15  *

    16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    17  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    19  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

    20  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    26  * POSSIBILITY OF SUCH DAMAGE.

    27  */

    29 #include <string.h>

    30 #include "cx/hash_map.h"

    31 #include "cx/utils.h"

    33 static void cx_hash_map_clear(struct cx_map_s *map) {

    34     struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;

    35     cx_for_n(i, hash_map->bucket_count) {

    36         struct cx_hash_map_element_s *elem = hash_map->buckets[i];

    37         if (elem != NULL) {

    38             do {

    39                 struct cx_hash_map_element_s *next = elem->next;

    40                 // free the key data

    41                 cxFree(map->allocator, elem->key.data.obj);

    42                 // free the node

    43                 cxFree(map->allocator, elem);

    44                 // proceed

    45                 elem = next;

    46             } while (elem != NULL);

    48             // do not leave a dangling pointer

    49             hash_map->buckets[i] = NULL;

    50         }

    51     }

    52     map->size = 0;

    53 }

    55 static void cx_hash_map_destructor(struct cx_map_s *map) {

    56     struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;

    58     // free the buckets

    59     cx_hash_map_clear(map);

    60     cxFree(map->allocator, hash_map->buckets);

    62     // free the map structure

    63     cxFree(map->allocator, map);

    64 }

    66 static int cx_hash_map_put(

    67         CxMap *map,

    68         CxHashKey key,

    69         void *value

    70 ) {

    71     struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;

    72     CxAllocator *allocator = map->allocator;

    74     unsigned hash = key.hash;

    75     if (hash == 0) {

    76         cx_hash_murmur(&key);

    77         hash = key.hash;

    78     }

    80     size_t slot = hash % hash_map->bucket_count;

    81     struct cx_hash_map_element_s *elm = hash_map->buckets[slot];

    82     struct cx_hash_map_element_s *prev = NULL;

    84     while (elm != NULL && elm->key.hash < hash) {

    85         prev = elm;

    86         elm = elm->next;

    87     }

    89     if (elm != NULL && elm->key.hash == hash) {

    90         // overwrite existing element

    91         elm->data = value;

    92     } else {

    93         // insert new element

    95         struct cx_hash_map_element_s *e = cxMalloc(allocator, sizeof(struct cx_hash_map_element_s));

    96         if (e == NULL) {

    97             return -1;

    98         }

   100         // write the value

   101         // TODO: depending on future map features, we may want to copy here

   102         e->data = value;

   104         // copy the key

   105         void *kd = cxMalloc(allocator, key.len);

   106         if (kd == NULL) {

   107             return -1;

   108         }

   109         memcpy(kd, key.data.obj, key.len);

   110         e->key.data.obj = kd;

   111         e->key.len = key.len;

   112         e->key.hash = hash;

   114         // insert the element into the linked list

   115         if (prev == NULL) {

   116             hash_map->buckets[slot] = e;

   117         } else {

   118             prev->next = e;

   119         }

   120         e->next = elm;

   122         // increase the size

   123         map->size++;

   124     }

   126     return 0;

   127 }

   129 static void cx_hash_map_unlink(

   130         struct cx_hash_map_s *hash_map,

   131         size_t slot,

   132         struct cx_hash_map_element_s *prev,

   133         struct cx_hash_map_element_s *elm

   134 ) {

   135     // unlink

   136     if (prev == NULL) {

   137         hash_map->buckets[slot] = elm->next;

   138     } else {

   139         prev->next = elm->next;

   140     }

   141     // free element

   142     cxFree(hash_map->base.allocator, elm->key.data.obj);

   143     cxFree(hash_map->base.allocator, elm);

   144     // decrease size

   145     hash_map->base.size--;

   146 }

   148 /**

   149  * Helper function to avoid code duplication.

   150  *

   151  * @param map the map

   152  * @param key the key to look up

   153  * @param remove flag indicating whether the looked up entry shall be removed

   154  * @return the value corresponding to the key or \c NULL

   155  */

   156 static void *cx_hash_map_get_remove(

   157         CxMap *map,

   158         CxHashKey key,

   159         bool remove

   160 ) {

   161     struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;

   163     unsigned hash = key.hash;

   164     if (hash == 0) {

   165         cx_hash_murmur(&key);

   166         hash = key.hash;

   167     }

   169     size_t slot = hash % hash_map->bucket_count;

   170     struct cx_hash_map_element_s *elm = hash_map->buckets[slot];

   171     struct cx_hash_map_element_s *prev = NULL;

   172     while (elm && elm->key.hash <= hash) {

   173         if (elm->key.hash == hash && elm->key.len == key.len) {

   174             if (memcmp(elm->key.data.obj, key.data.obj, key.len) == 0) {

   175                 void *data = elm->data;

   176                 if (remove) {

   177                     cx_hash_map_unlink(hash_map, slot, prev, elm);

   178                 }

   179                 return data;

   180             }

   181         }

   182         prev = elm;

   183         elm = prev->next;

   184     }

   186     return NULL;

   187 }

   189 static void *cx_hash_map_get(

   190         CxMap const *map,

   191         CxHashKey key

   192 ) {

   193     // we can safely cast, because we know when remove=false, the map stays untouched

   194     return cx_hash_map_get_remove((CxMap *) map, key, false);

   195 }

   197 static void *cx_hash_map_remove(

   198         CxMap *map,

   199         CxHashKey key

   200 ) {

   201     return cx_hash_map_get_remove(map, key, true);

   202 }

   204 static void *cx_hash_map_iter_current_entry(CxIterator const *iter) {

   205     // struct has to have a compatible signature

   206     return (struct cx_map_entry_s *) &(iter->kv_data);

   207 }

   209 static void *cx_hash_map_iter_current_key(CxIterator const *iter) {

   210     struct cx_hash_map_element_s *elm = iter->elem_handle;

   211     return &elm->key;

   212 }

   214 static void *cx_hash_map_iter_current_value(CxIterator const *iter) {

   215     struct cx_hash_map_element_s *elm = iter->elem_handle;

   216     // TODO: return a pointer to data if this map is storing copies

   217     return elm->data;

   218 }

   220 static bool cx_hash_map_iter_valid(CxIterator const *iter) {

   221     return iter->elem_handle != NULL;

   222 }

   224 static void cx_hash_map_iter_next(CxIterator *iter) {

   225     struct cx_hash_map_s *map = iter->src_handle;

   226     struct cx_hash_map_element_s *elm = iter->elem_handle;

   228     // remove current element, if asked

   229     if (iter->remove) {

   230         // clear the flag

   231         iter->remove = false;

   233         // determine the next element

   234         struct cx_hash_map_element_s *next = elm->next;

   236         // search the previous element

   237         struct cx_hash_map_element_s *prev = NULL;

   238         if (map->buckets[iter->slot] != elm) {

   239             prev = map->buckets[iter->slot];

   240             while (prev->next != elm) {

   241                 prev = prev->next;

   242             }

   243         }

   245         // unlink

   246         cx_hash_map_unlink(map, iter->slot, prev, elm);

   248         // advance

   249         elm = next;

   250     } else {

   251         // just advance

   252         elm = elm->next;

   253         iter->index++;

   254     }

   256     // search the next bucket, if required

   257     while (elm == NULL && ++iter->slot < map->bucket_count) {

   258         elm = map->buckets[iter->slot];

   259     }

   261     // fill the struct with the next element

   262     iter->elem_handle = elm;

   263     if (elm == NULL) {

   264         iter->kv_data.key = NULL;

   265         iter->kv_data.value = NULL;

   266     } else {

   267         iter->kv_data.key = &elm->key;

   268         // TODO: pointer to data if this map is storing copies

   269         iter->kv_data.value = elm->data;

   270     }

   271 }

   273 static CxIterator cx_hash_map_iterator(CxMap *map) {

   274     CxIterator iter;

   276     iter.src_handle = map;

   277     iter.valid = cx_hash_map_iter_valid;

   278     iter.next = cx_hash_map_iter_next;

   279     iter.current = cx_hash_map_iter_current_entry;

   281     iter.slot = 0;

   282     iter.index = 0;

   283     iter.remove = false;

   285     if (map->size > 0) {

   286         struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;

   287         struct cx_hash_map_element_s *elm = hash_map->buckets[0];

   288         for (; elm == NULL; iter.slot++) {

   289             elm = hash_map->buckets[iter.slot];

   290         }

   291         iter.elem_handle = elm;

   292         iter.kv_data.key = &elm->key;

   293         // TODO: pointer to data if this map is storing copies

   294         iter.kv_data.value = elm->data;

   295     } else {

   296         iter.elem_handle = NULL;

   297         iter.kv_data.key = NULL;

   298         iter.kv_data.value = NULL;

   299     }

   301     return iter;

   302 }

   304 static CxIterator cx_hash_map_iterator_keys(CxMap *map) {

   305     CxIterator iter = cx_hash_map_iterator(map);

   306     iter.current = cx_hash_map_iter_current_key;

   307     return iter;

   308 }

   310 static CxIterator cx_hash_map_iterator_values(CxMap *map) {

   311     CxIterator iter = cx_hash_map_iterator(map);

   312     iter.current = cx_hash_map_iter_current_value;

   313     return iter;

   314 }

   316 static cx_map_class cx_hash_map_class = {

   317         cx_hash_map_destructor,

   318         cx_hash_map_clear,

   319         cx_hash_map_put,

   320         cx_hash_map_get,

   321         cx_hash_map_remove,

   322         cx_hash_map_iterator,

   323         cx_hash_map_iterator_keys,

   324         cx_hash_map_iterator_values,

   325 };

   327 CxMap *cxHashMapCreate(

   328         CxAllocator *allocator,

   329         size_t buckets

   330 ) {

   331     if (buckets == 0) {

   332         // implementation defined default

   333         buckets = 16;

   334     }

   336     struct cx_hash_map_s *map = cxMalloc(allocator, sizeof(struct cx_hash_map_s));

   337     if (map == NULL) return NULL;

   339     // initialize hash map members

   340     map->bucket_count = buckets;

   341     map->buckets = cxCalloc(allocator, buckets, sizeof(struct cx_hash_map_element_s *));

   342     if (map->buckets == NULL) {

   343         cxFree(allocator, map);

   344         return NULL;

   345     }

   347     // initialize base members

   348     map->base.cl = &cx_hash_map_class;

   349     map->base.allocator = allocator;

   350     map->base.size = 0;

   352     return (CxMap *) map;

   353 }

   355 int cxMapRehash(CxMap *map) {

   356     struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;

   357     if (map->size > ((hash_map->bucket_count * 3) >> 2)) {

   359         size_t new_bucket_count = (map->size * 5) >> 1;

   360         struct cx_hash_map_element_s **new_buckets = cxCalloc(map->allocator,

   361                                                               new_bucket_count, sizeof(struct cx_hash_map_element_s *));

   363         if (new_buckets == NULL) {

   364             return 1;

   365         }

   367         // iterate through the elements and assign them to their new slots

   368         cx_for_n(slot, hash_map->bucket_count) {

   369             struct cx_hash_map_element_s *elm = hash_map->buckets[slot];

   370             while (elm != NULL) {

   371                 struct cx_hash_map_element_s *next = elm->next;

   372                 size_t new_slot = elm->key.hash % new_bucket_count;

   374                 // find position where to insert

   375                 struct cx_hash_map_element_s *bucket_next = new_buckets[new_slot];

   376                 struct cx_hash_map_element_s *bucket_prev = NULL;

   377                 while (bucket_next != NULL && bucket_next->key.hash < elm->key.hash) {

   378                     bucket_prev = bucket_next;

   379                     bucket_next = bucket_next->next;

   380                 }

   382                 // insert

   383                 if (bucket_prev == NULL) {

   384                     elm->next = new_buckets[new_slot];

   385                     new_buckets[new_slot] = elm;

   386                 } else {

   387                     bucket_prev->next = elm;

   388                     elm->next = bucket_next;

   389                 }

   391                 // advance

   392                 elm = next;

   393             }

   394         }

   396         // assign result to the map

   397         hash_map->bucket_count = new_bucket_count;

   398         cxFree(map->allocator, hash_map->buckets);

   399         hash_map->buckets = new_buckets;

   400     }

   401     return 0;

   402 }

Mercurial > hg > ucx / file revision

src/hash_map.c@d566bd3e6af8

src/hash_map.c