ucx: src/hash_map.c@69a83fad8a35

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

    91         if (e == NULL) {

    92             return -1;

    93         }

    95         // write the value

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

    97         e->data = value;

    99         // copy the key

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

   101         if (kd == NULL) {

   102             return -1;

   103         }

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

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

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

   107         e->key.hash = hash;

   109         // insert the element into the linked list

   110         if (prev == NULL) {

   111             hash_map->buckets[slot] = e;

   112         } else {

   113             prev->next = e;

   114         }

   115         e->next = elm;

   117         // increase the size

   118         map->size++;

   119     } else {

   120         // (elem != NULL && elem->key.hash == hash) - overwrite value of existing element

   121         elm->data = value;

   122     }

   124     return 0;

   125 }

   127 static void cx_hash_map_unlink(

   128         struct cx_hash_map_s *hash_map,

   129         size_t slot,

   130         struct cx_hash_map_element_s *prev,

   131         struct cx_hash_map_element_s *elm

   132 ) {

   133     // unlink

   134     if (prev == NULL) {

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

   136     } else {

   137         prev->next = elm->next;

   138     }

   139     // free element

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

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

   142     // decrease size

   143     hash_map->base.size--;

   144 }

   146 /**

   147  * Helper function to avoid code duplication.

   148  *

   149  * @param map the map

   150  * @param key the key to look up

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

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

   153  */

   154 static void *cx_hash_map_get_remove(

   155         CxMap *map,

   156         CxHashKey key,

   157         bool remove

   158 ) {

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

   161     unsigned hash = key.hash;

   162     if (hash == 0) {

   163         cx_hash_murmur(&key);

   164         hash = key.hash;

   165     }

   167     size_t slot = hash % hash_map->bucket_count;

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

   169     struct cx_hash_map_element_s *prev = NULL;

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

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

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

   173                 void *data = elm->data;

   174                 if (remove) {

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

   176                 }

   177                 return data;

   178             }

   179         }

   180         prev = elm;

   181         elm = prev->next;

   182     }

   184     return NULL;

   185 }

   187 static void *cx_hash_map_get(

   188         CxMap const *map,

   189         CxHashKey key

   190 ) {

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

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

   193 }

   195 static void *cx_hash_map_remove(

   196         CxMap *map,

   197         CxHashKey key

   198 ) {

   199     return cx_hash_map_get_remove(map, key, true);

   200 }

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

   203     // struct has to have a compatible signature

   204     struct cx_map_entry_s *entry = (struct cx_map_entry_s *) &(iter->kv_data);

   205     return entry;

   206 }

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

   209     struct cx_hash_map_element_s *elm = iter->elem_handle;

   210     return &elm->key;

   211 }

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

   214     struct cx_hash_map_element_s *elm = iter->elem_handle;

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

   216     return elm->data;

   217 }

   219 static bool cx_hash_map_iter_valid(CxIterator const *iter) {

   220     return iter->elem_handle != NULL;

   221 }

   223 static void cx_hash_map_iter_next(CxIterator *iter) {

   224     struct cx_hash_map_s *map = iter->src_handle;

   225     struct cx_hash_map_element_s *elm = iter->elem_handle;

   227     // remove current element, if asked

   228     if (iter->remove) {

   229         // clear the flag

   230         iter->remove = false;

   232         // determine the next element

   233         struct cx_hash_map_element_s *next = elm->next;

   235         // search the previous element

   236         struct cx_hash_map_element_s *prev = NULL;

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

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

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

   240                 prev = prev->next;

   241             }

   242         }

   244         // unlink

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

   247         // advance

   248         elm = next;

   249     } else {

   250         // just advance

   251         elm = elm->next;

   252         iter->index++;

   253     }

   255     // search the next bucket, if required

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

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

   258     }

   260     // fill the struct with the next element

   261     iter->elem_handle = elm;

   262     if (elm == NULL) {

   263         iter->kv_data.key = NULL;

   264         iter->kv_data.value = NULL;

   265     } else {

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

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

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

   269     }

   270 }

   272 static CxIterator cx_hash_map_iterator(CxMap *map) {

   273     CxIterator iter;

   275     iter.src_handle = map;

   276     iter.valid = cx_hash_map_iter_valid;

   277     iter.next = cx_hash_map_iter_next;

   278     iter.current = cx_hash_map_iter_current_entry;

   280     iter.slot = 0;

   281     iter.index = 0;

   282     iter.remove = false;

   284     if (map->size > 0) {

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

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

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

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

   289         }

   290         iter.elem_handle = elm;

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

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

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

   294     } else {

   295         iter.elem_handle = NULL;

   296         iter.kv_data.key = NULL;

   297         iter.kv_data.value = NULL;

   298     }

   300     return iter;

   301 }

   303 static CxIterator cx_hash_map_iterator_keys(CxMap *map) {

   304     CxIterator iter = cx_hash_map_iterator(map);

   305     iter.current = cx_hash_map_iter_current_key;

   306     return iter;

   307 }

   309 static CxIterator cx_hash_map_iterator_values(CxMap *map) {

   310     CxIterator iter = cx_hash_map_iterator(map);

   311     iter.current = cx_hash_map_iter_current_value;

   312     return iter;

   313 }

   315 static cx_map_class cx_hash_map_class = {

   316         cx_hash_map_destructor,

   317         cx_hash_map_clear,

   318         cx_hash_map_put,

   319         cx_hash_map_get,

   320         cx_hash_map_remove,

   321         cx_hash_map_iterator,

   322         cx_hash_map_iterator_keys,

   323         cx_hash_map_iterator_values,

   324 };

   326 CxMap *cxHashMapCreate(

   327         CxAllocator *allocator,

   328         size_t buckets

   329 ) {

   330     if (buckets == 0) {

   331         // implementation defined default

   332         buckets = 16;

   333     }

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

   336     if (map == NULL) return NULL;

   338     // initialize hash map members

   339     map->bucket_count = buckets;

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

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

   342         cxFree(allocator, map);

   343         return NULL;

   344     }

   346     // initialize base members

   347     map->base.cl = &cx_hash_map_class;

   348     map->base.allocator = allocator;

   349     map->base.size = 0;

   351     return (CxMap *) map;

   352 }

   354 int cxMapRehash(CxMap *map) {

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

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

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

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

   360                                                               new_bucket_count, sizeof(struct cx_hash_map_element_s *));

   362         if (new_buckets == NULL) {

   363             return 1;

   364         }

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

   367         cx_for_n(slot, hash_map->bucket_count) {

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

   369             while (elm != NULL) {

   370                 struct cx_hash_map_element_s *next = elm->next;

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

   373                 // find position where to insert

   374                 struct cx_hash_map_element_s *bucket_next = new_buckets[new_slot];

   375                 struct cx_hash_map_element_s *bucket_prev = NULL;

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

   377                     bucket_prev = bucket_next;

   378                     bucket_next = bucket_next->next;

   379                 }

   381                 // insert

   382                 if (bucket_prev == NULL) {

   383                     elm->next = new_buckets[new_slot];

   384                     new_buckets[new_slot] = elm;

   385                 } else {

   386                     bucket_prev->next = elm;

   387                     elm->next = bucket_next;

   388                 }

   390                 // advance

   391                 elm = next;

   392             }

   393         }

   395         // assign result to the map

   396         hash_map->bucket_count = new_bucket_count;

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

   398         hash_map->buckets = new_buckets;

   399     }

   400     return 0;

   401 }

Mercurial > hg > ucx / file revision

src/hash_map.c@69a83fad8a35

src/hash_map.c