ucx: src/hash_map.c@3f3a0d19db58

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

   205 }

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

   208     struct cx_hash_map_element_s *elm = iter->elem_handle;

   209     return &elm->key;

   210 }

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

   213     struct cx_hash_map_element_s *elm = iter->elem_handle;

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

   215     return elm->data;

   216 }

   218 static bool cx_hash_map_iter_valid(CxIterator const *iter) {

   219     return iter->elem_handle != NULL;

   220 }

   222 static void cx_hash_map_iter_next(CxIterator *iter) {

   223     struct cx_hash_map_s *map = iter->src_handle;

   224     struct cx_hash_map_element_s *elm = iter->elem_handle;

   226     // remove current element, if asked

   227     if (iter->remove) {

   228         // clear the flag

   229         iter->remove = false;

   231         // determine the next element

   232         struct cx_hash_map_element_s *next = elm->next;

   234         // search the previous element

   235         struct cx_hash_map_element_s *prev = NULL;

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

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

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

   239                 prev = prev->next;

   240             }

   241         }

   243         // unlink

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

   246         // advance

   247         elm = next;

   248     } else {

   249         // just advance

   250         elm = elm->next;

   251         iter->index++;

   252     }

   254     // search the next bucket, if required

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

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

   257     }

   259     // fill the struct with the next element

   260     iter->elem_handle = elm;

   261     if (elm == NULL) {

   262         iter->kv_data.key = NULL;

   263         iter->kv_data.value = NULL;

   264     } else {

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

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

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

   268     }

   269 }

   271 static CxIterator cx_hash_map_iterator(CxMap *map) {

   272     CxIterator iter;

   274     iter.src_handle = map;

   275     iter.valid = cx_hash_map_iter_valid;

   276     iter.next = cx_hash_map_iter_next;

   277     iter.current = cx_hash_map_iter_current_entry;

   279     iter.slot = 0;

   280     iter.index = 0;

   281     iter.remove = false;

   283     if (map->size > 0) {

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

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

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

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

   288         }

   289         iter.elem_handle = elm;

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

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

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

   293     } else {

   294         iter.elem_handle = NULL;

   295         iter.kv_data.key = NULL;

   296         iter.kv_data.value = NULL;

   297     }

   299     return iter;

   300 }

   302 static CxIterator cx_hash_map_iterator_keys(CxMap *map) {

   303     CxIterator iter = cx_hash_map_iterator(map);

   304     iter.current = cx_hash_map_iter_current_key;

   305     return iter;

   306 }

   308 static CxIterator cx_hash_map_iterator_values(CxMap *map) {

   309     CxIterator iter = cx_hash_map_iterator(map);

   310     iter.current = cx_hash_map_iter_current_value;

   311     return iter;

   312 }

   314 static cx_map_class cx_hash_map_class = {

   315         cx_hash_map_destructor,

   316         cx_hash_map_clear,

   317         cx_hash_map_put,

   318         cx_hash_map_get,

   319         cx_hash_map_remove,

   320         cx_hash_map_iterator,

   321         cx_hash_map_iterator_keys,

   322         cx_hash_map_iterator_values,

   323 };

   325 CxMap *cxHashMapCreate(

   326         CxAllocator *allocator,

   327         size_t buckets

   328 ) {

   329     if (buckets == 0) {

   330         // implementation defined default

   331         buckets = 16;

   332     }

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

   335     if (map == NULL) return NULL;

   337     // initialize hash map members

   338     map->bucket_count = buckets;

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

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

   341         cxFree(allocator, map);

   342         return NULL;

   343     }

   345     // initialize base members

   346     map->base.cl = &cx_hash_map_class;

   347     map->base.allocator = allocator;

   348     map->base.size = 0;

   350     return (CxMap *) map;

   351 }

   353 int cxMapRehash(CxMap *map) {

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

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

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

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

   359                                                               new_bucket_count, sizeof(struct cx_hash_map_element_s *));

   361         if (new_buckets == NULL) {

   362             return 1;

   363         }

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

   366         cx_for_n(slot, hash_map->bucket_count) {

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

   368             while (elm != NULL) {

   369                 struct cx_hash_map_element_s *next = elm->next;

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

   372                 // find position where to insert

   373                 struct cx_hash_map_element_s *bucket_next = new_buckets[new_slot];

   374                 struct cx_hash_map_element_s *bucket_prev = NULL;

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

   376                     bucket_prev = bucket_next;

   377                     bucket_next = bucket_next->next;

   378                 }

   380                 // insert

   381                 if (bucket_prev == NULL) {

   382                     elm->next = new_buckets[new_slot];

   383                     new_buckets[new_slot] = elm;

   384                 } else {

   385                     bucket_prev->next = elm;

   386                     elm->next = bucket_next;

   387                 }

   389                 // advance

   390                 elm = next;

   391             }

   392         }

   394         // assign result to the map

   395         hash_map->bucket_count = new_bucket_count;

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

   397         hash_map->buckets = new_buckets;

   398     }

   399     return 0;

   400 }

Mercurial > hg > ucx / file revision

src/hash_map.c@3f3a0d19db58

src/hash_map.c