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
|
#include <u.h>
#include <unistd.h>
#include <sys/time.h>
#include <sched.h>
#include <errno.h>
#include <libc.h>
static pthread_mutex_t initmutex = PTHREAD_MUTEX_INITIALIZER;
static void
lockinit(Lock *lk)
{
pthread_mutexattr_t attr;
pthread_mutex_lock(&initmutex);
if(lk->init == 0){
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);
pthread_mutex_init(&lk->mutex, &attr);
pthread_mutexattr_destroy(&attr);
lk->init = 1;
}
pthread_mutex_unlock(&initmutex);
}
void
lock(Lock *lk)
{
if(!lk->init)
lockinit(lk);
if(pthread_mutex_lock(&lk->mutex) != 0)
abort();
}
int
canlock(Lock *lk)
{
int r;
if(!lk->init)
lockinit(lk);
r = pthread_mutex_trylock(&lk->mutex);
if(r == 0)
return 1;
if(r == EBUSY)
return 0;
abort();
}
void
unlock(Lock *lk)
{
if(pthread_mutex_unlock(&lk->mutex) != 0)
abort();
}
|
