'''This file is part of AToMPM - A Tool for Multi-Paradigm Modelling
Copyright 2011 by the AToMPM team and licensed under the LGPL
See COPYING.lesser and README.md in the root of this project for full details'''

from threading import *

#Barrier implementation from here
#From http://greenteapress.com/semaphores/index.html
class barrier:
    def __init__(self, n):
        self.n = n
        self.count = 0
        self.mutex = Semaphore(1)
        self.turnstile = Semaphore(0)
        self.turnstile2 = Semaphore(0)

    def phase1(self):
        self.mutex.acquire()
        self.count += 1
        if self.count == self.n:
            for i in range(self.n):
                self.turnstile.release()
        self.mutex.release()
        self.turnstile.acquire()

    def phase2(self):
        self.mutex.acquire()
        self.count -= 1
        if self.count == 0:
            for i in range(self.n):
                self.turnstile2.release()
        self.mutex.release()
        self.turnstile2.acquire()

    def wait(self):
        self.phase1()
        self.phase2()