proto semaphore

protosem.py

import threading

mutex1 = threading.Lock()
sem_limit = 5
sem_count = sem_limit
lista1 = []

def acquire_sem():
  mutex1.acquire()
  if sem_count == 0:
    current_thread = threading.current_thread()
    lista1.append(current_thread)
    mutex1.release()
    current_thread.sleep()
  else:
    sem_count -= 1
    mutex1.release()

def release_sem():
  mutex1.acquire()
  if sem_count < sem_limit:
    ll1 = len(lista1)
    i = 0
    while True:
      t = lista1[i]
      if t.is_sleep():
        t.wake_up()
        lista1.remove(i)
        break
      i = (i+1) % ll1
    sem_count += 1
  mutex1.release()