usr.sbin/nscd/hashtable.h

   1 /*-
   2  * Copyright (c) 2005 Michael Bushkov <bushman@rsu.ru>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #ifndef __CACHELIB_HASHTABLE_H__
  28 #define __CACHELIB_HASHTABLE_H__
  29
  30 #include <string.h>
  31
  32 #define HASHTABLE_INITIAL_ENTRIES_CAPACITY 8
  33 typedef unsigned int hashtable_index_t;
  34
  35 /*
  36  * This file contains queue.h-like macro definitions for hash tables.
  37  * Hash table is organized as an array of the specified size of the user
  38  * defined (with HASTABLE_ENTRY_HEAD) structures. Each hash table
  39  * entry (user defined structure) stores its elements in the sorted array.
  40  * You can place elements into the hash table, retrieve elements with
  41  * specified key, traverse through all elements, and delete them.
  42  * New elements are placed into the hash table by using the compare and
  43  * hashing functions, provided by the user.
  44  */
  45
  46 /*
  47  * Defines the hash table entry structure, that uses specified type of
  48  * elements.
  49  */
  50 #define HASHTABLE_ENTRY_HEAD(name, type) struct name {                  \
  51         type    *values;                                                \
  52         size_t capacity;                                                \
  53         size_t size;                                                    \
  54 }
  55
  56 /*
  57  * Defines the hash table structure, which uses the specified type of entries.
  58  * The only restriction for entries is that is that they should have the field,
  59  * defined with HASHTABLE_ENTRY_HEAD macro.
  60  */
  61 #define HASHTABLE_HEAD(name, entry) struct name {                       \
  62         struct entry    *entries;                                       \
  63         size_t          entries_size;                                   \
  64 }
  65
  66 #define HASHTABLE_ENTRIES_COUNT(table)                                  \
  67         ((table)->entries_size)
  68
  69 /*
  70  * Unlike most of queue.h data types, hash tables can not be initialized
  71  * statically - so there is no HASHTABLE_HEAD_INITIALIZED macro.
  72  */
  73 #define HASHTABLE_INIT(table, type, field, _entries_size)               \
  74         do {                                                            \
  75                 hashtable_index_t var;                                  \
  76                 (table)->entries = calloc(_entries_size,                \
  77                         sizeof(*(table)->entries));                     \
  78                 (table)->entries_size = (_entries_size);                \
  79                 for (var = 0; var < HASHTABLE_ENTRIES_COUNT(table); ++var) {\
  80                         (table)->entries[var].field.capacity =          \
  81                                 HASHTABLE_INITIAL_ENTRIES_CAPACITY;     \
  82                         (table)->entries[var].field.size = 0;           \
  83                         (table)->entries[var].field.values = malloc(    \
  84                                 sizeof(type) *                          \
  85                                 HASHTABLE_INITIAL_ENTRIES_CAPACITY);    \
  86                         assert((table)->entries[var].field.values != NULL);\
  87                 }                                                       \
  88         } while (0)
  89
  90 /*
  91  * All initialized hashtables should be destroyed with this macro.
  92  */
  93 #define HASHTABLE_DESTROY(table, field)                                 \
  94         do {                                                            \
  95                 hashtable_index_t var;                                  \
  96                 for (var = 0; var < HASHTABLE_ENTRIES_COUNT(table); ++var) {\
  97                         free((table)->entries[var].field.values);       \
  98                 }                                                       \
  99         } while (0)
 100
 101 #define HASHTABLE_GET_ENTRY(table, hash)                                \
 102         (&((table)->entries[hash]))
 103
 104 /*
 105  * Traverses through all hash table entries
 106  */
 107 #define HASHTABLE_FOREACH(table, var)                                   \
 108         for ((var) = &((table)->entries[0]);                            \
 109                 (var) < &((table)->entries[HASHTABLE_ENTRIES_COUNT(table)]);\
 110                 ++(var))
 111
 112 /*
 113  * Traverses through all elements of the specified hash table entry
 114  */
 115 #define HASHTABLE_ENTRY_FOREACH(entry, field, var)                      \
 116         for ((var) = &((entry)->field.values[0]);                       \
 117                 (var) < &((entry)->field.values[(entry)->field.size]);  \
 118                 ++(var))
 119
 120 #define HASHTABLE_ENTRY_CLEAR(entry, field)                             \
 121         ((entry)->field.size = 0)
 122
 123 #define HASHTABLE_ENTRY_SIZE(entry, field)                              \
 124         ((entry)->field.size)
 125
 126 #define HASHTABLE_ENTRY_CAPACITY(entry, field)                          \
 127         ((entry)->field.capacity)
 128
 129 #define HASHTABLE_ENTRY_CAPACITY_INCREASE(entry, field, type)           \
 130         do {                                                            \
 131                 (entry)->field.capacity *= 2;                           \
 132                 (entry)->field.values = realloc((entry)->field.values,  \
 133                          (entry)->field.capacity * sizeof(type));       \
 134         } while (0)
 135
 136 #define HASHTABLE_ENTRY_CAPACITY_DECREASE(entry, field, type)           \
 137         do {                                                            \
 138                 (entry)->field.capacity /= 2;                           \
 139                 (entry)->field.values = realloc((entry)->field.values,  \
 140                         (entry)->field.capacity * sizeof(type));        \
 141         } while (0)
 142
 143 /*
 144  * Generates prototypes for the hash table functions
 145  */
 146 #define HASHTABLE_PROTOTYPE(name, entry_, type)                         \
 147 hashtable_index_t name##_CALCULATE_HASH(struct name *, type *);         \
 148 void name##_ENTRY_STORE(struct entry_*, type *);                        \
 149 type *name##_ENTRY_FIND(struct entry_*, type *);                        \
 150 type *name##_ENTRY_FIND_SPECIAL(struct entry_ *, type *,                \
 151         int (*) (const void *, const void *));                          \
 152 void name##_ENTRY_REMOVE(struct entry_*, type *);
 153
 154 /*
 155  * Generates implementations of the hash table functions
 156  */
 157 #define HASHTABLE_GENERATE(name, entry_, type, field, HASH, CMP)        \
 158 hashtable_index_t name##_CALCULATE_HASH(struct name *table, type *data) \
 159 {                                                                       \
 160                                                                         \
 161         return HASH(data, table->entries_size);                         \
 162 }                                                                       \
 163                                                                         \
 164 void name##_ENTRY_STORE(struct entry_ *the_entry, type *data)           \
 165 {                                                                       \
 166                                                                         \
 167         if (the_entry->field.size == the_entry->field.capacity)         \
 168                 HASHTABLE_ENTRY_CAPACITY_INCREASE(the_entry, field, type);\
 169                                                                         \
 170         memcpy(&(the_entry->field.values[the_entry->field.size++]),     \
 171                 data,                                                   \
 172                 sizeof(type));                                          \
 173         qsort(the_entry->field.values, the_entry->field.size,           \
 174                 sizeof(type), CMP);                                     \
 175 }                                                                       \
 176                                                                         \
 177 type *name##_ENTRY_FIND(struct entry_ *the_entry, type *key)            \
 178 {                                                                       \
 179                                                                         \
 180         return ((type *)bsearch(key, the_entry->field.values,           \
 181                 the_entry->field.size, sizeof(type), CMP));             \
 182 }                                                                       \
 183                                                                         \
 184 type *name##_ENTRY_FIND_SPECIAL(struct entry_ *the_entry, type *key,    \
 185         int (*compar) (const void *, const void *))                     \
 186 {                                                                       \
 187         return ((type *)bsearch(key, the_entry->field.values,           \
 188                 the_entry->field.size, sizeof(type), compar));          \
 189 }                                                                       \
 190                                                                         \
 191 void name##_ENTRY_REMOVE(struct entry_ *the_entry, type *del_elm)       \
 192 {                                                                       \
 193                                                                         \
 194         memmove(del_elm, del_elm + 1,                                   \
 195                 (&the_entry->field.values[--the_entry->field.size] - del_elm) *\
 196                 sizeof(type));                                          \
 197 }
 198
 199 /*
 200  * Macro definitions below wrap the functions, generaed with
 201  * HASHTABLE_GENERATE macro. You should use them and avoid using generated
 202  * functions directly.
 203  */
 204 #define HASHTABLE_CALCULATE_HASH(name, table, data)                     \
 205         (name##_CALCULATE_HASH((table), data))
 206
 207 #define HASHTABLE_ENTRY_STORE(name, entry, data)                        \
 208         name##_ENTRY_STORE((entry), data)
 209
 210 #define HASHTABLE_ENTRY_FIND(name, entry, key)                          \
 211         (name##_ENTRY_FIND((entry), (key)))
 212
 213 #define HASHTABLE_ENTRY_FIND_SPECIAL(name, entry, key, cmp)             \
 214         (name##_ENTRY_FIND_SPECIAL((entry), (key), (cmp)))
 215
 216 #define HASHTABLE_ENTRY_REMOVE(name, entry, del_elm)                    \
 217         name##_ENTRY_REMOVE((entry), (del_elm))
 218
 219 #endif