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