/*
* Philosopher code
*/
static void *dp_thread(void *arg)
{
int think_rnd;
int eat_rnd;
int i;
philosopher *me;
me = (philosopher *) arg;
me->tid = gettid();
while (!stop) {
think_rnd = (rand() % 10000);
eat_rnd = (rand() % 10000);
/*
* Think a random number of thoughts before getting hungry
*/
for (i = 0; i < think_rnd; i++){
think_one_thought();
}
/*
* Grab both chopsticks
*/
#if DEADLOCK
/*
* This order results in deadlock
*/
pthread_mutex_lock(left_chop(me));
pthread_mutex_lock(right_chop(me));
#else
/*
* This order avoids deadlock
*/
if(me->id % 2 == 0) {
pthread_mutex_lock(left_chop(me));
pthread_mutex_lock(right_chop(me));
} else {
pthread_mutex_lock(right_chop(me));
pthread_mutex_lock(left_chop(me));
}
#endif
/*
* Eat some random amount of food
*/
for (i = 0; i < eat_rnd; i++){
eat_one_mouthful();
}
/*
* Release both chopsticks
*/
pthread_mutex_unlock(right_chop(me));
pthread_mutex_unlock(left_chop(me));
}
return NULL;
}
/*
* Philosopher code which makes each philosopher eat and think for a
* random period of time.
*/
static void *dp_thread(void *arg)
{
int eat_rnd;
int i;
int id;
philosopher *me;
int think_rnd;
me = (philosopher *) arg;
id = me->id;
/*
* While the gobal Stop flag is not set, keep thinking and eating
* like a good Philosopher.
*/
while (!Stop) {
/*
* Determine how long to think and eat in this cycle. Limit the
* values to defined maximum values.
*/
think_rnd = (rand() % MAX_PHIL_THINK_PERIOD);
eat_rnd = (rand() % MAX_PHIL_EAT_PERIOD);
/*
* Think a random number of thoughts before getting hungry. this
* is a loop with a lot of overhead, since we call a subroutine
* for each thought. That is a feature, not a bug, in this case as
* we want each thought to be several machine instructions.
*/
for (i = 0; i < think_rnd; i++){
think_one_thought();
}
/*
* Grab both chopsticks: ASYMMETRIC and WAITER SOLUTION
*/
pthread_mutex_lock(left_chop(me));
pthread_mutex_lock(right_chop(me));
/*
* Eat some random amount of food. Again, this involves a
* subroutine call for each mouthful, which is a feature, not a
* bug.
*/
for (i = 0; i < eat_rnd; i++){
eat_one_mouthful();
}
/*
* Release both chopsticks: WAITER SOLUTION
*/
pthread_mutex_unlock(right_chop(me));
pthread_mutex_unlock(left_chop(me));
/*
* Update my progress in current session and for all time.
*/
me->prog++;
me->prog_total++;
}
/*
* Philosopher thread finished, so rejoin parent
*/
return NULL;
}