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#include <u.h>
#include <libc.h>
#ifdef PTHREAD
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();
}
#else
/* old, non-pthread systems */
int
canlock(Lock *lk)
{
return !tas(&lk->key);
}
void
lock(Lock *lk)
{
int i;
/* easy case */
if(canlock(lk))
return;
/* for multi processor machines */
for(i=0; i<100; i++)
if(canlock(lk))
return;
for(i=0; i<100; i++) {
osyield();
if(canlock(lk))
return;
}
/* looking bad - make sure it is not a priority problem */
for(i=0; i<12; i++) {
osmsleep(1<<i);
if(canlock(lk))
return;
}
/* we are in trouble */
for(;;) {
if(canlock(lk))
return;
iprint("lock loop %ld: val=%d &lock=%ux pc=%p\n", getpid(), lk->key, lk, getcallerpc(&lk));
osmsleep(1000);
}
}
void
unlock(Lock *lk)
{
assert(lk->key);
lk->key = 0;
}
#endif
void
ilock(Lock *lk)
{
lock(lk);
}
void
iunlock(Lock *lk)
{
unlock(lk);
}
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