TASK_DLLEXPORT int
Task_wait_read(int fd, long msec)
{
Task *tp;
struct timeval tv;
fd_set set;
int r;
if (!canSwitch)
{
FD_ZERO(&set);
FD_SET(fd, &set);
calcTv(&tv, msec);
r = t_select(FD_SETSIZE, &set, 0, 0, &tv);
if (r > 0)
return 0;
else if (r == 0)
return 1;
else
return r;
}
tp = currTask;
FD_ZERO(&set);
FD_SET(fd, &set);
tv.tv_sec = tv.tv_usec = 0;
r = t_select(FD_SETSIZE, &set, 0, 0, &tv);
if (r != 0)
{
Task_yield();
if (r > 0)
return 0;
else
return r;
}
FD_ZERO(&tp->rfileset);
FD_SET(fd, &tp->rfileset);
tp->wakeUp = calcWakeup(msec);
removeFromList(tp);
tp->isRead = 1;
addToWait(tp);
tp->isTimed = 0;
Task_yield();
tp->isRead = 0;
return tp->isTimed;
}
//call before moving to a new area
//called on a chef to check if other chefs
//are executing recipes that could cause a deadlock
//if a deadlock case could occur based on the order of the
//recipes on the other two chefs, the called on chef downs its
//own semaphore, which should be 0, going to sleep.
//To wake a chef, call clearAreas(Data *mychef)
void checkChefs(Data *mychef) {
int i, j, semval;
//loop through the array of data structs
//protect shared list of data
sem_wait(&s_list);
for(i = 0; i < 3; i++) {
sem_getvalue(&chefs[i].sem,&semval);
if(mychef->step == -1) {
if(mychef->recipe.tasks[0].a == chefs[i].recipe.tasks[chefs[i].step].a) {
addToWait(mychef, &chefs[i]);
//release data list and go to sleep
sem_post(&s_list);
sem_wait(&chefs[mychef->ID].sem);
}
}
//check for deadlocks based on recipes
//only loop through recipies of awake, executing chefs
if((semval > -1)&&(chefs[i].ID != mychef->ID)) {
for(j = chefs[i].recipe.numTasks; j > -1; j--) {
//check a deadlock case in which my area is the next area of another chef
//and my next area is currently occupied by that chef
if((mychef->recipe.tasks[mychef->step].a == chefs[i].recipe.tasks[j+1].a) &&
(mychef->recipe.tasks[(mychef->step)+1].a == chefs[i].recipe.tasks[j].a)) {
addToWait(mychef, &chefs[i]);
//release data list and go to sleep
sem_post(&s_list);
sem_wait(&(chefs[mychef->ID].sem));
printf("Chef %d is going to sleep in %s area",mychef->ID, getAreaStr(mychef->recipe.tasks[mychef->step].a));
}
}
}
//check if mychef's next area is currently occupied by another chef
if(mychef->recipe.tasks[(mychef->step)+1].a == chefs[i].recipe.tasks[chefs[i].step].a) {
addToWait(mychef, &chefs[i]);
//release data list and go to sleep
sem_post(&s_list);
sem_wait(&(chefs[mychef->ID].sem));
}
}
}
