1 #include <u.h>
2 #include <libc.h>
3 #include <bio.h>
4 #include <ndb.h>
5
6 struct Ndbcache
7 {
8 Ndbcache *next;
9 char *attr;
10 char *val;
11 Ndbs s;
12 Ndbtuple *t;
13 };
14
15 enum
16 {
17 Maxcached= 128,
18 };
19
20 static void
ndbcachefree(Ndbcache * c)21 ndbcachefree(Ndbcache *c)
22 {
23 free(c->val);
24 free(c->attr);
25 if(c->t)
26 ndbfree(c->t);
27 free(c);
28 }
29
30 static Ndbtuple*
ndbcopy(Ndb * db,Ndbtuple * from_t,Ndbs * from_s,Ndbs * to_s)31 ndbcopy(Ndb *db, Ndbtuple *from_t, Ndbs *from_s, Ndbs *to_s)
32 {
33 Ndbtuple *first, *to_t, *last, *line;
34 int newline;
35
36 *to_s = *from_s;
37 to_s->t = nil;
38 to_s->db = db;
39
40 newline = 1;
41 last = nil;
42 first = nil;
43 line = nil;
44 for(; from_t != nil; from_t = from_t->entry){
45 to_t = ndbnew(from_t->attr, from_t->val);
46
47 /* have s point to matching tuple */
48 if(from_s->t == from_t)
49 to_s->t = to_t;
50
51 if(newline)
52 line = to_t;
53 else
54 last->line = to_t;
55
56 if(last != nil)
57 last->entry = to_t;
58 else {
59 first = to_t;
60 line = to_t;
61 }
62 to_t->entry = nil;
63 to_t->line = line;
64 last = to_t;
65 newline = from_t->line != from_t->entry;
66 }
67 ndbsetmalloctag(first, getcallerpc(&db));
68 return first;
69 }
70
71 /*
72 * if found, move to front
73 */
74 int
_ndbcachesearch(Ndb * db,Ndbs * s,char * attr,char * val,Ndbtuple ** t)75 _ndbcachesearch(Ndb *db, Ndbs *s, char *attr, char *val, Ndbtuple **t)
76 {
77 Ndbcache *c, **l;
78
79 *t = nil;
80 c = nil;
81 for(l = &db->cache; *l != nil; l = &(*l)->next){
82 c = *l;
83 if(strcmp(c->attr, attr) == 0 && strcmp(c->val, val) == 0)
84 break;
85 }
86 if(*l == nil)
87 return -1;
88
89 /* move to front */
90 *l = c->next;
91 c->next = db->cache;
92 db->cache = c;
93
94 *t = ndbcopy(db, c->t, &c->s, s);
95 return 0;
96 }
97
98 Ndbtuple*
_ndbcacheadd(Ndb * db,Ndbs * s,char * attr,char * val,Ndbtuple * t)99 _ndbcacheadd(Ndb *db, Ndbs *s, char *attr, char *val, Ndbtuple *t)
100 {
101 Ndbcache *c, **l;
102
103 c = mallocz(sizeof *c, 1);
104 if(c == nil)
105 return nil;
106 c->attr = strdup(attr);
107 if(c->attr == nil)
108 goto err;
109 c->val = strdup(val);
110 if(c->val == nil)
111 goto err;
112 c->t = ndbcopy(db, t, s, &c->s);
113 if(c->t == nil && t != nil)
114 goto err;
115
116 /* add to front */
117 c->next = db->cache;
118 db->cache = c;
119
120 /* trim list */
121 if(db->ncache < Maxcached){
122 db->ncache++;
123 return t;
124 }
125 for(l = &db->cache; (*l)->next; l = &(*l)->next)
126 ;
127 c = *l;
128 *l = nil;
129 err:
130 ndbcachefree(c);
131 ndbsetmalloctag(t, getcallerpc(&db));
132 return t;
133 }
134
135 void
_ndbcacheflush(Ndb * db)136 _ndbcacheflush(Ndb *db)
137 {
138 Ndbcache *c;
139
140 while(db->cache != nil){
141 c = db->cache;
142 db->cache = c->next;
143 ndbcachefree(c);
144 }
145 db->ncache = 0;
146 }
147