eating = waiting = 0 // keep track of the number of threads/customers
mutex = Semaphore (1) // mutex protects both counters (eating and wating)
block = Semaphore (0) // incoming customers' queue (regular meaning)
must_wait = False // indicates that the bar is full

# take control of the counters
mutex.wait ( )

# if there are 5 people already sitting at the table
if must_wait:
    # increment the number of customers waiting outside
    waiting += 1
    # free the semaphore for another thread to use
    mutex.signal ( )
    # take control of the queue of customers
    block.wait ( )

# else there's an empty seat at the table.
else:
    # increment the number of customers eating at the bar
    eating += 1
    # figure out if customers will have to wait
    must_wait = (eating == 5)
    # free the semaphore so another thread can use
    mutex.signal ( )

//eat sushi

# acquire access to the eating and waiting counters
mutex.wait ( )

# eating is complete so decrement the counter for people eating at the bar
eating -= 1

# if no one is eating at the bar
if eating == 0:
    # take 5 more customers or however many people are waiting if it is less
    n = min (5, waiting)

    # set counters
    waiting -= n
    eating += n

    # see if new customers will have to wait.
    must_wait = (eating == 5)

    # release lock on queue
    block.signal (n)

# release lock on counters
mutex.signal ( )