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/* hash table and linked lists, for libreswan
*
* Copyright (C) 2015, 2017, 2019 Andrew Cagney
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <https://www.gnu.org/licenses/gpl2.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#ifndef HASH_TABLE_H
#define HASH_TABLE_H
#include "list_entry.h"
#include "shunk.h" /* has constant ptr */
#include "where.h"
/*
* Generic hash table.
*/
typedef struct { unsigned hash; } hash_t;
extern const hash_t zero_hash;
struct hash_table {
const struct list_info *const info;
hash_t (*hasher)(const void *data);
struct list_entry *(*entry)(void *data);
long nr_entries; /* approx? */
unsigned long nr_slots;
struct list_head *slots;
};
#define HASH_TABLE(STRUCT, NAME, FIELD, NR_BUCKETS) \
\
LIST_INFO(STRUCT, STRUCT##_db_entries.NAME, \
STRUCT##_##NAME##_hash_info, jam_##STRUCT); \
\
static hash_t hash_table_hash_##STRUCT##_##NAME(const void *data) \
{ \
const struct STRUCT *s = data; \
return hash_##STRUCT##_##NAME(&(*s)FIELD); \
} \
\
static struct list_head STRUCT##_##NAME##_buckets[NR_BUCKETS]; \
\
static struct list_entry *hash_table_entry_##STRUCT##_##NAME(void *data) \
{ \
struct STRUCT *s = data; \
return &s->STRUCT##_db_entries.NAME; \
} \
\
struct hash_table STRUCT##_##NAME##_hash_table = { \
.hasher = hash_table_hash_##STRUCT##_##NAME, \
.entry = hash_table_entry_##STRUCT##_##NAME, \
.nr_slots = NR_BUCKETS, \
.slots = STRUCT##_##NAME##_buckets, \
.info = &STRUCT##_##NAME##_hash_info, \
}
void init_hash_table(struct hash_table *table, struct logger *logger);
void check_hash_table(struct hash_table *table, struct logger *logger);
hash_t hash_bytes(const void *ptr, size_t len, hash_t hash);
#define hash_hunk(HUNK, HASH) \
({ \
typeof(HUNK) h_ = HUNK; /* evaluate once */ \
hash_bytes(h_.ptr, h_.len, HASH); \
})
#define hash_thing(THING, HASH) \
({ \
shunk_t h_ = THING_AS_SHUNK(THING); /* evaluate once */ \
hash_bytes(h_.ptr, h_.len, HASH); \
})
/*
* Maintain the table.
*
* Use the terms "add" and "del" as this table has no true ordering
* beyond new being the most recent insertion - rehash does "del" then
* "add" which re-orders things.
*/
void init_hash_table_entry(struct hash_table *table, void *data);
void add_hash_table_entry(struct hash_table *table, void *data);
void del_hash_table_entry(struct hash_table *table, void *data);
#define HASH_DB(STRUCT, TABLE, ...) \
\
/* backup list for when there is no accelerator */ \
\
LIST_INFO(STRUCT, STRUCT##_db_entries.list, \
STRUCT##_db_list_info, jam_##STRUCT); \
\
static struct list_head STRUCT##_db_list_head = \
INIT_LIST_HEAD(&STRUCT##_db_list_head, \
&STRUCT##_db_list_info); \
\
struct hash_table *const STRUCT##_db_hash_tables[] = { \
TABLE, ##__VA_ARGS__, \
}; \
\
void STRUCT##_db_init(struct logger *logger) \
{ \
FOR_EACH_ELEMENT(h, STRUCT##_db_hash_tables) { \
init_hash_table(*h, logger); \
} \
} \
\
void STRUCT##_db_check(struct logger *logger) \
{ \
FOR_EACH_ELEMENT(h, STRUCT##_db_hash_tables) { \
check_hash_table(*h, logger); \
} \
} \
\
void STRUCT##_db_init_##STRUCT(struct STRUCT *s) \
{ \
init_list_entry(&STRUCT##_db_list_info, s, \
&s->STRUCT##_db_entries.list); \
FOR_EACH_ELEMENT(H, STRUCT##_db_hash_tables) { \
init_hash_table_entry(*H, s); \
} \
} \
\
void STRUCT##_db_add(struct STRUCT *s) \
{ \
insert_list_entry(&STRUCT##_db_list_head, \
&s->STRUCT##_db_entries.list); \
FOR_EACH_ELEMENT(H, STRUCT##_db_hash_tables) { \
add_hash_table_entry(*H, s); \
} \
} \
\
void STRUCT##_db_del(struct STRUCT *s) \
{ \
remove_list_entry(&s->STRUCT##_db_entries.list); \
FOR_EACH_ELEMENT(h, STRUCT##_db_hash_tables) { \
del_hash_table_entry(*h, s); \
} \
}
/* not all code requires rehashing */
#define REHASH_DB(STRUCT) \
void STRUCT##_db_rehash(struct STRUCT *s) \
{ \
FOR_EACH_ELEMENT(h, STRUCT##_db_hash_tables) { \
del_hash_table_entry(*h, s); \
add_hash_table_entry(*h, s); \
} \
}
#define REHASH_DB_ENTRY(STRUCT, NAME, FIELD) \
void STRUCT##_db_rehash_##NAME(struct STRUCT *s) \
{ \
del_hash_table_entry(&STRUCT##_##NAME##_hash_table, s); \
add_hash_table_entry(&STRUCT##_##NAME##_hash_table, s); \
}
/*
* Return the head of the list entries that match HASH.
*
* Use this, in conjunction with FOR_EACH_LIST_ENTRY, when searching.
*
* Don't forget to also check that the object itself matches - more
* than one hash can map to the same list of entries.
*/
struct list_head *hash_table_bucket(struct hash_table *table, hash_t hash);
#endif
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