1 /* Licensed under LGPLv2+ - see LICENSE file for details */
2 #ifndef CCAN_HTABLE_H
3 #define CCAN_HTABLE_H
4 #include "config.h"
5 #include <ccan/str/str.h>
6 #include <stdint.h>
7 #include <stdbool.h>
8 #include <stdlib.h>
9
10 /* Define CCAN_HTABLE_DEBUG for expensive debugging checks on each call. */
11 #define HTABLE_LOC __FILE__ ":" stringify(__LINE__)
12 #ifdef CCAN_HTABLE_DEBUG
13 #define htable_debug(h, loc) htable_check((h), loc)
14 #else
15 #define htable_debug(h, loc) ((void)loc, h)
16 #endif
17
18 /**
19 * struct htable - private definition of a htable.
20 *
21 * It's exposed here so you can put it in your structures and so we can
22 * supply inline functions.
23 */
24 struct htable {
25 size_t (*rehash)(const void *elem, void *priv);
26 void *priv;
27 unsigned int bits, perfect_bitnum;
28 size_t elems, deleted;
29 /* These are the bits which are the same in all pointers. */
30 uintptr_t common_mask, common_bits;
31 uintptr_t *table;
32 };
33
34 /**
35 * HTABLE_INITIALIZER - static initialization for a hash table.
36 * @name: name of this htable.
37 * @rehash: hash function to use for rehashing.
38 * @priv: private argument to @rehash function.
39 *
40 * This is useful for setting up static and global hash tables.
41 *
42 * Example:
43 * // For simplicity's sake, say hash value is contents of elem.
44 * static size_t rehash(const void *elem, void *unused)
45 * {
46 * (void)unused;
47 * return *(size_t *)elem;
48 * }
49 * static struct htable ht = HTABLE_INITIALIZER(ht, rehash, NULL);
50 */
51 #define HTABLE_INITIALIZER(name, rehash, priv) \
52 { rehash, priv, 0, 0, 0, 0, -1, 0, &name.common_bits }
53
54 /**
55 * htable_init - initialize an empty hash table.
56 * @ht: the hash table to initialize
57 * @rehash: hash function to use for rehashing.
58 * @priv: private argument to @rehash function.
59 */
60 void htable_init(struct htable *ht,
61 size_t (*rehash)(const void *elem, void *priv), void *priv);
62
63 /**
64 * htable_init_sized - initialize an empty hash table of given size.
65 * @ht: the hash table to initialize
66 * @rehash: hash function to use for rehashing.
67 * @priv: private argument to @rehash function.
68 * @size: the number of element.
69 *
70 * If this returns false, @ht is still usable, but may need to do reallocation
71 * upon an add. If this returns true, it will not need to reallocate within
72 * @size htable_adds.
73 */
74 bool htable_init_sized(struct htable *ht,
75 size_t (*rehash)(const void *elem, void *priv),
76 void *priv, size_t size);
77
78 /**
79 * htable_count - count number of entries in a hash table.
80 * @ht: the hash table
81 */
htable_count(const struct htable * ht)82 static inline size_t htable_count(const struct htable *ht)
83 {
84 return ht->elems;
85 }
86
87 /**
88 * htable_clear - empty a hash table.
89 * @ht: the hash table to clear
90 *
91 * This doesn't do anything to any pointers left in it.
92 */
93 void htable_clear(struct htable *ht);
94
95
96 /**
97 * htable_check - check hash table for consistency
98 * @ht: the htable
99 * @abortstr: the location to print on aborting, or NULL.
100 *
101 * Because hash tables have redundant information, consistency checking that
102 * each element is in the correct location can be done. This is useful as a
103 * debugging check. If @abortstr is non-NULL, that will be printed in a
104 * diagnostic if the htable is inconsistent, and the function will abort.
105 *
106 * Returns the htable if it is consistent, NULL if not (it can never return
107 * NULL if @abortstr is set).
108 */
109 struct htable *htable_check(const struct htable *ht, const char *abortstr);
110
111 /**
112 * htable_copy - duplicate a hash table.
113 * @dst: the hash table to overwrite
114 * @src: the hash table to copy
115 *
116 * Only fails on out-of-memory.
117 *
118 * Equivalent to (but faster than):
119 * if (!htable_init_sized(dst, src->rehash, src->priv, 1U << src->bits))
120 * return false;
121 * v = htable_first(src, &i);
122 * while (v) {
123 * htable_add(dst, v);
124 * v = htable_next(src, i);
125 * }
126 * return true;
127 */
128 #define htable_copy(dst, src) htable_copy_(dst, htable_debug(src, HTABLE_LOC))
129 bool htable_copy_(struct htable *dst, const struct htable *src);
130
131 /**
132 * htable_add - add a pointer into a hash table.
133 * @ht: the htable
134 * @hash: the hash value of the object
135 * @p: the non-NULL pointer
136 *
137 * Also note that this can only fail due to allocation failure. Otherwise, it
138 * returns true.
139 */
140 #define htable_add(ht, hash, p) \
141 htable_add_(htable_debug(ht, HTABLE_LOC), hash, p)
142 bool htable_add_(struct htable *ht, size_t hash, const void *p);
143
144 /**
145 * htable_del - remove a pointer from a hash table
146 * @ht: the htable
147 * @hash: the hash value of the object
148 * @p: the pointer
149 *
150 * Returns true if the pointer was found (and deleted).
151 */
152 #define htable_del(ht, hash, p) \
153 htable_del_(htable_debug(ht, HTABLE_LOC), hash, p)
154 bool htable_del_(struct htable *ht, size_t hash, const void *p);
155
156 /**
157 * struct htable_iter - iterator or htable_first or htable_firstval etc.
158 *
159 * This refers to a location inside the hashtable.
160 */
161 struct htable_iter {
162 size_t off;
163 };
164
165 /**
166 * htable_firstval - find a candidate for a given hash value
167 * @htable: the hashtable
168 * @i: the struct htable_iter to initialize
169 * @hash: the hash value
170 *
171 * You'll need to check the value is what you want; returns NULL if none.
172 * See Also:
173 * htable_delval()
174 */
175 #define htable_firstval(htable, i, hash) \
176 htable_firstval_(htable_debug(htable, HTABLE_LOC), i, hash)
177
178 void *htable_firstval_(const struct htable *htable,
179 struct htable_iter *i, size_t hash);
180
181 /**
182 * htable_nextval - find another candidate for a given hash value
183 * @htable: the hashtable
184 * @i: the struct htable_iter to initialize
185 * @hash: the hash value
186 *
187 * You'll need to check the value is what you want; returns NULL if no more.
188 */
189 #define htable_nextval(htable, i, hash) \
190 htable_nextval_(htable_debug(htable, HTABLE_LOC), i, hash)
191 void *htable_nextval_(const struct htable *htable,
192 struct htable_iter *i, size_t hash);
193
194 /**
195 * htable_get - find an entry in the hash table
196 * @ht: the hashtable
197 * @h: the hash value of the entry
198 * @cmp: the comparison function
199 * @ptr: the pointer to hand to the comparison function.
200 *
201 * Convenient inline wrapper for htable_firstval/htable_nextval loop.
202 */
htable_get(const struct htable * ht,size_t h,bool (* cmp)(const void * candidate,void * ptr),const void * ptr)203 static inline void *htable_get(const struct htable *ht,
204 size_t h,
205 bool (*cmp)(const void *candidate, void *ptr),
206 const void *ptr)
207 {
208 struct htable_iter i;
209 void *c;
210
211 for (c = htable_firstval(ht,&i,h); c; c = htable_nextval(ht,&i,h)) {
212 if (cmp(c, (void *)ptr))
213 return c;
214 }
215 return NULL;
216 }
217
218 /**
219 * htable_first - find an entry in the hash table
220 * @ht: the hashtable
221 * @i: the struct htable_iter to initialize
222 *
223 * Get an entry in the hashtable; NULL if empty.
224 */
225 #define htable_first(htable, i) \
226 htable_first_(htable_debug(htable, HTABLE_LOC), i)
227 void *htable_first_(const struct htable *htable, struct htable_iter *i);
228
229 /**
230 * htable_next - find another entry in the hash table
231 * @ht: the hashtable
232 * @i: the struct htable_iter to use
233 *
234 * Get another entry in the hashtable; NULL if all done.
235 * This is usually used after htable_first or prior non-NULL htable_next.
236 */
237 #define htable_next(htable, i) \
238 htable_next_(htable_debug(htable, HTABLE_LOC), i)
239 void *htable_next_(const struct htable *htable, struct htable_iter *i);
240
241 /**
242 * htable_prev - find the previous entry in the hash table
243 * @ht: the hashtable
244 * @i: the struct htable_iter to use
245 *
246 * Get previous entry in the hashtable; NULL if all done.
247 *
248 * "previous" here only means the item that would have been returned by
249 * htable_next() before the item it returned most recently.
250 *
251 * This is usually used in the middle of (or after) a htable_next iteration and
252 * to "unwind" actions taken.
253 */
254 #define htable_prev(htable, i) \
255 htable_prev_(htable_debug(htable, HTABLE_LOC), i)
256 void *htable_prev_(const struct htable *htable, struct htable_iter *i);
257
258 /**
259 * htable_delval - remove an iterated pointer from a hash table
260 * @ht: the htable
261 * @i: the htable_iter
262 *
263 * Usually used to delete a hash entry after it has been found with
264 * htable_firstval etc.
265 */
266 #define htable_delval(htable, i) \
267 htable_delval_(htable_debug(htable, HTABLE_LOC), i)
268 void htable_delval_(struct htable *ht, struct htable_iter *i);
269
270 /**
271 * htable_pick - set iterator to a random valid entry.
272 * @ht: the htable
273 * @seed: a random number to use.
274 * @i: the htable_iter which is output (or NULL).
275 *
276 * Usually used with htable_delval to delete a random entry. Returns
277 * NULL iff the table is empty, otherwise a random entry.
278 */
279 #define htable_pick(htable, seed, i) \
280 htable_pick_(htable_debug(htable, HTABLE_LOC), seed, i)
281 void *htable_pick_(const struct htable *ht, size_t seed, struct htable_iter *i);
282
283 /**
284 * htable_set_allocator - set calloc/free functions.
285 * @alloc: allocator to use, must zero memory!
286 * @free: unallocator to use (@p is NULL or a return from @alloc)
287 */
288 void htable_set_allocator(void *(*alloc)(struct htable *, size_t len),
289 void (*free)(struct htable *, void *p));
290 #endif /* CCAN_HTABLE_H */
291