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 "hash.h"
  20
  21 static struct shash_node *shash_find__(const struct shash *,
  22                                        const char *name, size_t name_len,
  23                                        size_t hash);
  24
  25 static size_t
  26 hash_name(const char *name)
  27 {
  28     return hash_string(name, 0);
  29 }
  30
  31 void
  32 shash_init(struct shash *sh)
  33 {
  34     hmap_init(&sh->map);
  35 }
  36
  37 void
  38 shash_destroy(struct shash *sh)
  39 {
  40     if (sh) {
  41         shash_clear(sh);
  42         hmap_destroy(&sh->map);
  43     }
  44 }
  45
  46 /* Like shash_destroy(), but also free() each node's 'data'. */
  47 void
  48 shash_destroy_free_data(struct shash *sh)
  49 {
  50     if (sh) {
  51         shash_clear_free_data(sh);
  52         hmap_destroy(&sh->map);
  53     }
  54 }
  55
  56 void
  57 shash_swap(struct shash *a, struct shash *b)
  58 {
  59     hmap_swap(&a->map, &b->map);
  60 }
  61
  62 void
  63 shash_moved(struct shash *sh)
  64 {
  65     hmap_moved(&sh->map);
  66 }
  67
  68 void
  69 shash_clear(struct shash *sh)
  70 {
  71     struct shash_node *node, *next;
  72
  73     SHASH_FOR_EACH_SAFE (node, next, sh) {
  74         hmap_remove(&sh->map, &node->node);
  75         free(node->name);
  76         free(node);
  77     }
  78 }
  79
  80 /* Like shash_clear(), but also free() each node's 'data'. */
  81 void
  82 shash_clear_free_data(struct shash *sh)
  83 {
  84     struct shash_node *node, *next;
  85
  86     SHASH_FOR_EACH_SAFE (node, next, sh) {
  87         hmap_remove(&sh->map, &node->node);
  88         free(node->data);
  89         free(node->name);
  90         free(node);
  91     }
  92 }
  93
  94 bool
  95 shash_is_empty(const struct shash *shash)
  96 {
  97     return hmap_is_empty(&shash->map);
  98 }
  99
 100 size_t
 101 shash_count(const struct shash *shash)
 102 {
 103     return hmap_count(&shash->map);
 104 }
 105
 106 static struct shash_node *
 107 shash_add_nocopy__(struct shash *sh, char *name, const void *data, size_t hash)
 108 {
 109     struct shash_node *node = xmalloc(sizeof *node);
 110     node->name = name;
 111     node->data = CONST_CAST(void *, data);
 112     hmap_insert(&sh->map, &node->node, hash);
 113     return node;
 114 }
 115
 116 /* It is the caller's responsibility to avoid duplicate names, if that is
 117  * desirable. */
 118 struct shash_node *
 119 shash_add_nocopy(struct shash *sh, char *name, const void *data)
 120 {
 121     return shash_add_nocopy__(sh, name, data, hash_name(name));
 122 }
 123
 124 /* It is the caller's responsibility to avoid duplicate names, if that is
 125  * desirable. */
 126 struct shash_node *
 127 shash_add(struct shash *sh, const char *name, const void *data)
 128 {
 129     return shash_add_nocopy(sh, xstrdup(name), data);
 130 }
 131
 132 bool
 133 shash_add_once(struct shash *sh, const char *name, const void *data)
 134 {
 135     if (!shash_find(sh, name)) {
 136         shash_add(sh, name, data);
 137         return true;
 138     } else {
 139         return false;
 140     }
 141 }
 142
 143 void
 144 shash_add_assert(struct shash *sh, const char *name, const void *data)
 145 {
 146     bool added OVS_UNUSED = shash_add_once(sh, name, data);
 147     ovs_assert(added);
 148 }
 149
 150 /* Searches for 'name' in 'sh'.  If it does not already exist, adds it along
 151  * with 'data' and returns NULL.  If it does already exist, replaces its data
 152  * by 'data' and returns the data that it formerly contained. */
 153 void *
 154 shash_replace(struct shash *sh, const char *name, const void *data)
 155 {
 156     size_t hash = hash_name(name);
 157     struct shash_node *node;
 158
 159     node = shash_find__(sh, name, strlen(name), hash);
 160     if (!node) {
 161         shash_add_nocopy__(sh, xstrdup(name), data, hash);
 162         return NULL;
 163     } else {
 164         void *old_data = node->data;
 165         node->data = CONST_CAST(void *, data);
 166         return old_data;
 167     }
 168 }
 169
 170 /* Deletes 'node' from 'sh' and frees the node's name.  The caller is still
 171  * responsible for freeing the node's data, if necessary. */
 172 void
 173 shash_delete(struct shash *sh, struct shash_node *node)
 174 {
 175     free(shash_steal(sh, node));
 176 }
 177
 178 /* Deletes 'node' from 'sh'.  Neither the node's name nor its data is freed;
 179  * instead, ownership is transferred to the caller.  Returns the node's
 180  * name. */
 181 char *
 182 shash_steal(struct shash *sh, struct shash_node *node)
 183 {
 184     char *name = node->name;
 185
 186     hmap_remove(&sh->map, &node->node);
 187     free(node);
 188     return name;
 189 }
 190
 191 static struct shash_node *
 192 shash_find__(const struct shash *sh, const char *name, size_t name_len,
 193              size_t hash)
 194 {
 195     struct shash_node *node;
 196
 197     HMAP_FOR_EACH_WITH_HASH (node, node, hash, &sh->map) {
 198         if (!strncmp(node->name, name, name_len) && !node->name[name_len]) {
 199             return node;
 200         }
 201     }
 202     return NULL;
 203 }
 204
 205 /* If there are duplicates, returns a random element. */
 206 struct shash_node *
 207 shash_find(const struct shash *sh, const char *name)
 208 {
 209     return shash_find__(sh, name, strlen(name), hash_name(name));
 210 }
 211
 212 /* Finds and returns a shash_node within 'sh' that has the given 'name' that is
 213  * exactly 'len' bytes long.  Returns NULL if no node in 'sh' has that name. */
 214 struct shash_node *
 215 shash_find_len(const struct shash *sh, const char *name, size_t len)
 216 {
 217     return shash_find__(sh, name, len, hash_bytes(name, len, 0));
 218 }
 219
 220 void *
 221 shash_find_data(const struct shash *sh, const char *name)
 222 {
 223     struct shash_node *node = shash_find(sh, name);
 224     return node ? node->data : NULL;
 225 }
 226
 227 void *
 228 shash_find_and_delete(struct shash *sh, const char *name)
 229 {
 230     struct shash_node *node = shash_find(sh, name);
 231     if (node) {
 232         void *data = node->data;
 233         shash_delete(sh, node);
 234         return data;
 235     } else {
 236         return NULL;
 237     }
 238 }
 239
 240 void *
 241 shash_find_and_delete_assert(struct shash *sh, const char *name)
 242 {
 243     void *data = shash_find_and_delete(sh, name);
 244     ovs_assert(data != NULL);
 245     return data;
 246 }
 247
 248 struct shash_node *
 249 shash_first(const struct shash *shash)
 250 {
 251     struct hmap_node *node = hmap_first(&shash->map);
 252     return node ? CONTAINER_OF(node, struct shash_node, node) : NULL;
 253 }
 254
 255 static int
 256 compare_nodes_by_name(const void *a_, const void *b_)
 257 {
 258     const struct shash_node *const *a = a_;
 259     const struct shash_node *const *b = b_;
 260     return strcmp((*a)->name, (*b)->name);
 261 }
 262
 263 const struct shash_node **
 264 shash_sort(const struct shash *sh)
 265 {
 266     if (shash_is_empty(sh)) {
 267         return NULL;
 268     } else {
 269         const struct shash_node **nodes;
 270         struct shash_node *node;
 271         size_t i, n;
 272
 273         n = shash_count(sh);
 274         nodes = xmalloc(n * sizeof *nodes);
 275         i = 0;
 276         SHASH_FOR_EACH (node, sh) {
 277             nodes[i++] = node;
 278         }
 279         ovs_assert(i == n);
 280
 281         qsort(nodes, n, sizeof *nodes, compare_nodes_by_name);
 282
 283         return nodes;
 284     }
 285 }
 286
 287 /* Returns true if 'a' and 'b' contain the same keys (regardless of their
 288  * values), false otherwise. */
 289 bool
 290 shash_equal_keys(const struct shash *a, const struct shash *b)
 291 {
 292     struct shash_node *node;
 293
 294     if (hmap_count(&a->map) != hmap_count(&b->map)) {
 295         return false;
 296     }
 297     SHASH_FOR_EACH (node, a) {
 298         if (!shash_find(b, node->name)) {
 299             return false;
 300         }
 301     }
 302     return true;
 303 }
 304
 305 /* Chooses and returns a randomly selected node from 'sh', which must not be
 306  * empty.
 307  *
 308  * I wouldn't depend on this algorithm to be fair, since I haven't analyzed it.
 309  * But it does at least ensure that any node in 'sh' can be chosen. */
 310 struct shash_node *
 311 shash_random_node(struct shash *sh)
 312 {
 313     return CONTAINER_OF(hmap_random_node(&sh->map), struct shash_node, node);
 314 }