lib/shash.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "shash.h"
  19 #include <assert.h>
  20 #include "hash.h"
  21
  22 static struct shash_node *shash_find__(const struct shash *,
  23                                        const char *name, size_t name_len,
  24                                        size_t hash);
  25
  26 static size_t
  27 hash_name(const char *name)
  28 {
  29     return hash_string(name, 0);
  30 }
  31
  32 void
  33 shash_init(struct shash *sh)
  34 {
  35     hmap_init(&sh->map);
  36 }
  37
  38 void
  39 shash_destroy(struct shash *sh)
  40 {
  41     if (sh) {
  42         shash_clear(sh);
  43         hmap_destroy(&sh->map);
  44     }
  45 }
  46
  47 /* Like shash_destroy(), but also free() each node's 'data'. */
  48 void
  49 shash_destroy_free_data(struct shash *sh)
  50 {
  51     if (sh) {
  52         shash_clear_free_data(sh);
  53         hmap_destroy(&sh->map);
  54     }
  55 }
  56
  57 void
  58 shash_swap(struct shash *a, struct shash *b)
  59 {
  60     hmap_swap(&a->map, &b->map);
  61 }
  62
  63 void
  64 shash_moved(struct shash *sh)
  65 {
  66     hmap_moved(&sh->map);
  67 }
  68
  69 void
  70 shash_clear(struct shash *sh)
  71 {
  72     struct shash_node *node, *next;
  73
  74     SHASH_FOR_EACH_SAFE (node, next, sh) {
  75         hmap_remove(&sh->map, &node->node);
  76         free(node->name);
  77         free(node);
  78     }
  79 }
  80
  81 /* Like shash_clear(), but also free() each node's 'data'. */
  82 void
  83 shash_clear_free_data(struct shash *sh)
  84 {
  85     struct shash_node *node, *next;
  86
  87     SHASH_FOR_EACH_SAFE (node, next, sh) {
  88         hmap_remove(&sh->map, &node->node);
  89         free(node->data);
  90         free(node->name);
  91         free(node);
  92     }
  93 }
  94
  95 bool
  96 shash_is_empty(const struct shash *shash)
  97 {
  98     return hmap_is_empty(&shash->map);
  99 }
 100
 101 size_t
 102 shash_count(const struct shash *shash)
 103 {
 104     return hmap_count(&shash->map);
 105 }
 106
 107 static struct shash_node *
 108 shash_add_nocopy__(struct shash *sh, char *name, const void *data, size_t hash)
 109 {
 110     struct shash_node *node = xmalloc(sizeof *node);
 111     node->name = name;
 112     node->data = CONST_CAST(void *, data);
 113     hmap_insert(&sh->map, &node->node, hash);
 114     return node;
 115 }
 116
 117 /* It is the caller's responsibility to avoid duplicate names, if that is
 118  * desirable. */
 119 struct shash_node *
 120 shash_add_nocopy(struct shash *sh, char *name, const void *data)
 121 {
 122     return shash_add_nocopy__(sh, name, data, hash_name(name));
 123 }
 124
 125 /* It is the caller's responsibility to avoid duplicate names, if that is
 126  * desirable. */
 127 struct shash_node *
 128 shash_add(struct shash *sh, const char *name, const void *data)
 129 {
 130     return shash_add_nocopy(sh, xstrdup(name), data);
 131 }
 132
 133 bool
 134 shash_add_once(struct shash *sh, const char *name, const void *data)
 135 {
 136     if (!shash_find(sh, name)) {
 137         shash_add(sh, name, data);
 138         return true;
 139     } else {
 140         return false;
 141     }
 142 }
 143
 144 void
 145 shash_add_assert(struct shash *sh, const char *name, const void *data)
 146 {
 147     bool added OVS_UNUSED = shash_add_once(sh, name, data);
 148     assert(added);
 149 }
 150
 151 /* Searches for 'name' in 'sh'.  If it does not already exist, adds it along
 152  * with 'data' and returns NULL.  If it does already exist, replaces its data
 153  * by 'data' and returns the data that it formerly contained. */
 154 void *
 155 shash_replace(struct shash *sh, const char *name, const void *data)
 156 {
 157     size_t hash = hash_name(name);
 158     struct shash_node *node;
 159
 160     node = shash_find__(sh, name, strlen(name), hash);
 161     if (!node) {
 162         shash_add_nocopy__(sh, xstrdup(name), data, hash);
 163         return NULL;
 164     } else {
 165         void *old_data = node->data;
 166         node->data = CONST_CAST(void *, data);
 167         return old_data;
 168     }
 169 }
 170
 171 /* Deletes 'node' from 'sh' and frees the node's name.  The caller is still
 172  * responsible for freeing the node's data, if necessary. */
 173 void
 174 shash_delete(struct shash *sh, struct shash_node *node)
 175 {
 176     free(shash_steal(sh, node));
 177 }
 178
 179 /* Deletes 'node' from 'sh'.  Neither the node's name nor its data is freed;
 180  * instead, ownership is transferred to the caller.  Returns the node's
 181  * name. */
 182 char *
 183 shash_steal(struct shash *sh, struct shash_node *node)
 184 {
 185     char *name = node->name;
 186
 187     hmap_remove(&sh->map, &node->node);
 188     free(node);
 189     return name;
 190 }
 191
 192 static struct shash_node *
 193 shash_find__(const struct shash *sh, const char *name, size_t name_len,
 194              size_t hash)
 195 {
 196     struct shash_node *node;
 197
 198     HMAP_FOR_EACH_WITH_HASH (node, node, hash, &sh->map) {
 199         if (!strncmp(node->name, name, name_len) && !node->name[name_len]) {
 200             return node;
 201         }
 202     }
 203     return NULL;
 204 }
 205
 206 /* If there are duplicates, returns a random element. */
 207 struct shash_node *
 208 shash_find(const struct shash *sh, const char *name)
 209 {
 210     return shash_find__(sh, name, strlen(name), hash_name(name));
 211 }
 212
 213 /* Finds and returns a shash_node within 'sh' that has the given 'name' that is
 214  * exactly 'len' bytes long.  Returns NULL if no node in 'sh' has that name. */
 215 struct shash_node *
 216 shash_find_len(const struct shash *sh, const char *name, size_t len)
 217 {
 218     return shash_find__(sh, name, len, hash_bytes(name, len, 0));
 219 }
 220
 221 void *
 222 shash_find_data(const struct shash *sh, const char *name)
 223 {
 224     struct shash_node *node = shash_find(sh, name);
 225     return node ? node->data : NULL;
 226 }
 227
 228 void *
 229 shash_find_and_delete(struct shash *sh, const char *name)
 230 {
 231     struct shash_node *node = shash_find(sh, name);
 232     if (node) {
 233         void *data = node->data;
 234         shash_delete(sh, node);
 235         return data;
 236     } else {
 237         return NULL;
 238     }
 239 }
 240
 241 void *
 242 shash_find_and_delete_assert(struct shash *sh, const char *name)
 243 {
 244     void *data = shash_find_and_delete(sh, name);
 245     assert(data != NULL);
 246     return data;
 247 }
 248
 249 struct shash_node *
 250 shash_first(const struct shash *shash)
 251 {
 252     struct hmap_node *node = hmap_first(&shash->map);
 253     return node ? CONTAINER_OF(node, struct shash_node, node) : NULL;
 254 }
 255
 256 static int
 257 compare_nodes_by_name(const void *a_, const void *b_)
 258 {
 259     const struct shash_node *const *a = a_;
 260     const struct shash_node *const *b = b_;
 261     return strcmp((*a)->name, (*b)->name);
 262 }
 263
 264 const struct shash_node **
 265 shash_sort(const struct shash *sh)
 266 {
 267     if (shash_is_empty(sh)) {
 268         return NULL;
 269     } else {
 270         const struct shash_node **nodes;
 271         struct shash_node *node;
 272         size_t i, n;
 273
 274         n = shash_count(sh);
 275         nodes = xmalloc(n * sizeof *nodes);
 276         i = 0;
 277         SHASH_FOR_EACH (node, sh) {
 278             nodes[i++] = node;
 279         }
 280         assert(i == n);
 281
 282         qsort(nodes, n, sizeof *nodes, compare_nodes_by_name);
 283
 284         return nodes;
 285     }
 286 }
 287
 288 /* Returns true if 'a' and 'b' contain the same keys (regardless of their
 289  * values), false otherwise. */
 290 bool
 291 shash_equal_keys(const struct shash *a, const struct shash *b)
 292 {
 293     struct shash_node *node;
 294
 295     if (hmap_count(&a->map) != hmap_count(&b->map)) {
 296         return false;
 297     }
 298     SHASH_FOR_EACH (node, a) {
 299         if (!shash_find(b, node->name)) {
 300             return false;
 301         }
 302     }
 303     return true;
 304 }
 305
 306 /* Chooses and returns a randomly selected node from 'sh', which must not be
 307  * empty.
 308  *
 309  * I wouldn't depend on this algorithm to be fair, since I haven't analyzed it.
 310  * But it does at least ensure that any node in 'sh' can be chosen. */
 311 struct shash_node *
 312 shash_random_node(struct shash *sh)
 313 {
 314     return CONTAINER_OF(hmap_random_node(&sh->map), struct shash_node, node);
 315 }