Answer:
int sumid=0; /* Shared var that contains the sum of the process ids currently accessing the file */
int waiting=0; /* Number of process waiting on the semaphore OkToAccess */
semaphore mutex=1; /* Our good old Semaphore variable ;) */
semaphore OKToAccess=0; /* The synchronization semaphore */
get_access(int id)
{
sem_wait(mutex);
while(sumid+id > n) {
waiting++;
sem_signal(mutex);
sem_wait(OKToAccess);
sem_wait(mutex);
}
sumid += id;
sem_signal(mutex);
}
release_access(int id)
{
int i;
sem_wait(mutex);
sumid -= id;
for (i=0; i < waiting;++i) {
sem_signal(OKToAccess);
}
waiting = 0;
sem_signal(mutex);
}
main()
{
get_access(id);
do_stuff();
release_access(id);
}
Some points to note about the solution:
release_access wakes up all waiting processes. It is NOT ok to wake up the first waiting process in this problem --- that process may have too large a value of id. Also, more than one process may be eligible to go in (if those processes have small ids) when one process releases access.
woken up processes try to see if they can get in. If not, they go back to sleep.
waiting is set to 0 in release_access after the for loop. That avoids unnecessary signals from subsequent release_accesses. Those signals would not make the solution wrong, just less efficient as processes will be woken up unnecessarily.
Circular errors are caused by adding the cell name of the active cell to its own formula.
The minor may be penalized with a jail sentence of up to thirty days for his second offence. A jail sentence of up to sixty days is possible for third offence. Under MCL 436, a minor is someone who is under twenty one years old. Such minors may not purchase, consume or be in possession of any alcoholic liquor. Possession of alcoholic drinks can be actual or constructive. It is actual when you have direct physical control over it and it is constructive when you know where it is and you have reasonable access to it.
Answer:
extends
Explanation:
When you create a subclass, you basically say "I'm creating a new class, but for now it will look and behave the same as that other class", then you add its own personality.
The syntax is:
class SubClass extends SuperClass
Where SubClass is your new subclass what inherits methods and variables from the SuperClass.
So, if you add nothing to the SubClass, it will be a carbon copy of the SuperClass. But you can add methods and variables exclusive to this SubClass that the SuperClass won't have.
