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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
#include <u.h>
#include <libc.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>
enum {
NHASH = 128
};
typedef struct Intlist Intlist;
struct Intlist
{
ulong id;
void* aux;
Intlist* link;
};
struct Intmap
{
RWLock rwlock;
Intlist* hash[NHASH];
void (*inc)(void*);
};
static ulong
hashid(ulong id)
{
return id%NHASH;
}
static void
nop(void *v)
{
USED(v);
}
Intmap*
allocmap(void (*inc)(void*))
{
Intmap *m;
m = emalloc9p(sizeof(*m));
if(inc == nil)
inc = nop;
m->inc = inc;
return m;
}
void
freemap(Intmap *map, void (*destroy)(void*))
{
int i;
Intlist *p, *nlink;
if(destroy == nil)
destroy = nop;
for(i=0; i<NHASH; i++){
for(p=map->hash[i]; p; p=nlink){
nlink = p->link;
destroy(p->aux);
free(p);
}
}
free(map);
}
static Intlist**
llookup(Intmap *map, ulong id)
{
Intlist **lf;
for(lf=&map->hash[hashid(id)]; *lf; lf=&(*lf)->link)
if((*lf)->id == id)
break;
return lf;
}
/*
* The RWlock is used as expected except that we allow
* inc() to be called while holding it. This is because we're
* locking changes to the tree structure, not to the references.
* Inc() is expected to have its own locking.
*/
void*
lookupkey(Intmap *map, ulong id)
{
Intlist *f;
void *v;
rlock(&map->rwlock);
if(f = *llookup(map, id)){
v = f->aux;
map->inc(v);
}else
v = nil;
runlock(&map->rwlock);
return v;
}
void*
insertkey(Intmap *map, ulong id, void *v)
{
Intlist *f;
void *ov;
ulong h;
wlock(&map->rwlock);
if(f = *llookup(map, id)){
/* no decrement for ov because we're returning it */
ov = f->aux;
f->aux = v;
}else{
f = emalloc9p(sizeof(*f));
f->id = id;
f->aux = v;
h = hashid(id);
f->link = map->hash[h];
map->hash[h] = f;
ov = nil;
}
wunlock(&map->rwlock);
return ov;
}
int
caninsertkey(Intmap *map, ulong id, void *v)
{
Intlist *f;
int rv;
ulong h;
wlock(&map->rwlock);
if(*llookup(map, id))
rv = 0;
else{
f = emalloc9p(sizeof *f);
f->id = id;
f->aux = v;
h = hashid(id);
f->link = map->hash[h];
map->hash[h] = f;
rv = 1;
}
wunlock(&map->rwlock);
return rv;
}
void*
deletekey(Intmap *map, ulong id)
{
Intlist **lf, *f;
void *ov;
wlock(&map->rwlock);
if(f = *(lf = llookup(map, id))){
ov = f->aux;
*lf = f->link;
free(f);
}else
ov = nil;
wunlock(&map->rwlock);
return ov;
}
|