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Viewing changes to lib9/lock.c

  • Committer: Bazaar Package Importer
  • Author(s): Daniel Baumann
  • Date: 2006-01-25 15:33:00 UTC
  • Revision ID: james.westby@ubuntu.com-20060125153300-6hh4p9wx8iqqply5
Tags: upstream-2
Import upstream version 2

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lib9/lock.c
 
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#include <u.h>
 
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#include <unistd.h>
 
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#include <sys/time.h>
 
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#include <sched.h>
 
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#include <errno.h>
 
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#include <libc.h>
 
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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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}