1 #include <u.h>
2 #include <unistd.h>
3 #include <sys/time.h>
4 #include <sched.h>
5 #include <errno.h>
6 #include <libc.h>
7 
8 static pthread_mutex_t initmutex = PTHREAD_MUTEX_INITIALIZER;
9 
10 static void
11 lockinit(Lock *lk)
12 {
13 	pthread_mutexattr_t attr;
14 
15 	pthread_mutex_lock(&initmutex);
16 	if(lk->init == 0){
17 		pthread_mutexattr_init(&attr);
18 		pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);
19 		pthread_mutex_init(&lk->mutex, &attr);
20 		pthread_mutexattr_destroy(&attr);
21 		lk->init = 1;
22 	}
23 	pthread_mutex_unlock(&initmutex);
24 }
25 
26 void
27 lock(Lock *lk)
28 {
29 	if(!lk->init)
30 		lockinit(lk);
31 	if(pthread_mutex_lock(&lk->mutex) != 0)
32 		abort();
33 }
34 
35 int
36 canlock(Lock *lk)
37 {
38 	int r;
39 
40 	if(!lk->init)
41 		lockinit(lk);
42 	r = pthread_mutex_trylock(&lk->mutex);
43 	if(r == 0)
44 		return 1;
45 	if(r == EBUSY)
46 		return 0;
47 	abort();
48 }
49 
50 void
51 unlock(Lock *lk)
52 {
53 	if(pthread_mutex_unlock(&lk->mutex) != 0)
54 		abort();
55 }