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/*
* spin4.c
*
* Declare a spinlock object, lock it, spin on it,
* and then unlock it again.
*
* For this to work on a single processor machine we have
* to static initialise the spinlock. This bypasses the
* check of the number of processors done by pthread_spin_init.
* This is a non-portable side-effect of this implementation.
*/
#include "test.h"
#include <sys/timeb.h>
pthread_spinlock_t lock = PTHREADS_SPINLOCK_INITIALIZER;
struct _timeb currSysTimeStart;
struct _timeb currSysTimeStop;
#define GetDurationMilliSecs(_TStart, _TStop) ((_TStop.time*1000+_TStop.millitm) \
- (_TStart.time*1000+_TStart.millitm))
static int washere = 0;
void * func(void * arg)
{
_ftime(&currSysTimeStart);
assert(pthread_spin_lock(&lock) == 0);
assert(pthread_spin_unlock(&lock) == 0);
_ftime(&currSysTimeStop);
washere = 1;
return (void *) GetDurationMilliSecs(currSysTimeStart, currSysTimeStop);
}
int
main()
{
long result = 0;
pthread_t t;
assert(pthread_spin_lock(&lock) == 0);
assert(pthread_create(&t, NULL, func, NULL) == 0);
/*
* This should relinqish the CPU to the func thread enough times
* to waste approximately 2000 millisecs only if the lock really
* is spinning in the func thread (assuming 10 millisec CPU quantum).
for (i = 0; i < 200; i++)
{
sched_yield();
}
assert(pthread_spin_unlock(&lock) == 0);
assert(pthread_join(t, (void *) &result) == 0);
assert(result > 1000);
assert(pthread_spin_destroy(&lock) == 0);
assert(washere == 1);
return 0;
}
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