blob: 8284ffd7ff0fd41320908102c0e8664a5a9f22d8 (
plain)
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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
/*
spin -a semaphore.p
pcc -DSAFETY -DREACH -DMEMLIM'='500 -o pan pan.c
pan -i
rm pan.* pan
*/
#define N 3
bit listlock;
byte value;
bit onlist[N];
bit waiting[N];
bit sleeping[N];
bit acquired[N];
inline lock(x)
{
atomic { x == 0; x = 1 }
}
inline unlock(x)
{
assert x==1;
x = 0
}
inline sleep(cond)
{
assert !sleeping[_pid];
assert !interrupted;
if
:: cond
:: atomic { else -> sleeping[_pid] = 1 } ->
!sleeping[_pid]
fi;
if
:: skip
:: interrupted = 1
fi
}
inline wakeup(id)
{
if
:: sleeping[id] == 1 -> sleeping[id] = 0
:: else
fi
}
inline semqueue()
{
lock(listlock);
assert !onlist[_pid];
onlist[_pid] = 1;
unlock(listlock)
}
inline semdequeue()
{
lock(listlock);
assert onlist[_pid];
onlist[_pid] = 0;
waiting[_pid] = 0;
unlock(listlock)
}
inline semwakeup(n)
{
byte i, j;
lock(listlock);
i = 0;
j = n;
do
:: (i < N && j > 0) ->
if
:: onlist[i] && waiting[i] ->
atomic { printf("kicked %d\n", i);
waiting[i] = 0 };
wakeup(i);
j--
:: else
fi;
i++
:: else -> break
od;
/* reset i and j to reduce state space */
i = 0;
j = 0;
unlock(listlock)
}
inline semrelease(n)
{
atomic { value = value+n; printf("release %d\n", n); };
semwakeup(n)
}
inline canacquire()
{
atomic { value > 0 -> value--; };
acquired[_pid] = 1
}
#define semawoke() !waiting[_pid]
inline semacquire(block)
{
if
:: atomic { canacquire() -> printf("easy acquire\n"); } ->
goto out
:: else
fi;
if
:: !block -> goto out
:: else
fi;
semqueue();
do
:: skip ->
waiting[_pid] = 1;
if
:: atomic { canacquire() -> printf("hard acquire\n"); } ->
break
:: else
fi;
sleep(semawoke())
if
:: interrupted ->
printf("%d interrupted\n", _pid);
break
:: !interrupted
fi
od;
semdequeue();
if
:: !waiting[_pid] ->
semwakeup(1)
:: else
fi;
out:
assert (!block || interrupted || acquired[_pid]);
assert !(interrupted && acquired[_pid]);
assert !waiting[_pid];
printf("%d done\n", _pid);
}
active[N] proctype acquire()
{
bit interrupted;
semacquire(1);
printf("%d finished\n", _pid);
skip
}
active proctype release()
{
byte k;
k = 0;
do
:: k < N ->
semrelease(1);
k++;
:: else -> break
od;
skip
}
/*
* If this guy, the highest-numbered proc, sticks
* around, then everyone else sticks around.
* This makes sure that we get a state line for
* everyone in a proc dump.
*/
active proctype dummy()
{
end: 0;
}
|
