1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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.
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.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
** A class for static sized hash tables where old entries are deleted in
** first-in-last-out to usage.
*/
#ifndef HASH_FILO_H
#define HASH_FILO_H
#ifdef __GNUC__
#pragma interface /* gcc class implementation */
#endif
class hash_filo_element
{
hash_filo_element *next_used,*prev_used;
public:
hash_filo_element() {}
friend class hash_filo;
};
class hash_filo
{
const uint size, key_offset, key_length;
const hash_get_key get_key;
void (*free_element)(void*);
bool init;
hash_filo_element *first_link,*last_link;
public:
pthread_mutex_t lock;
HASH cache;
hash_filo(uint size_arg, uint key_offset_arg , uint key_length_arg,
hash_get_key get_key_arg,void (*free_element_arg)(void*))
:size(size_arg), key_offset(key_offset_arg), key_length(key_length_arg),
get_key(get_key_arg), free_element(free_element_arg),init(0)
{
bzero((char*) &cache,sizeof(cache));
}
~hash_filo()
{
if (init)
{
if (cache.array.buffer) /* Avoid problems with thread library */
(void) hash_free(&cache);
pthread_mutex_destroy(&lock);
}
}
void clear(bool locked=0)
{
if (!init)
{
init=1;
(void) pthread_mutex_init(&lock,NULL);
}
if (!locked)
(void) pthread_mutex_lock(&lock);
(void) hash_free(&cache);
(void) hash_init(&cache,size,key_offset, key_length, get_key, free_element,
0);
if (!locked)
(void) pthread_mutex_unlock(&lock);
first_link=last_link=0;
}
hash_filo_element *search(gptr key,uint length)
{
hash_filo_element *entry=(hash_filo_element*)
hash_search(&cache,(byte*) key,length);
if (entry)
{ // Found; link it first
if (entry != first_link)
{ // Relink used-chain
if (entry == last_link)
last_link=entry->prev_used;
else
{
entry->next_used->prev_used = entry->prev_used;
entry->prev_used->next_used = entry->next_used;
}
if ((entry->next_used= first_link))
first_link->prev_used=entry;
first_link=entry;
}
}
return entry;
}
my_bool add(hash_filo_element *entry)
{
if (cache.records == size)
{
hash_filo_element *tmp=last_link;
last_link=last_link->prev_used;
hash_delete(&cache,(byte*) tmp);
}
if (hash_insert(&cache,(byte*) entry))
{
if (free_element)
(*free_element)(entry); // This should never happen
return 1;
}
if ((entry->next_used=first_link))
first_link->prev_used=entry;
else
last_link=entry;
first_link=entry;
return 0;
}
};
#endif
|
