Vector clock implementation

vector_clock.py

from multiprocessing import Process, Pipe
from os import getpid
from datetime import datetime
from time import sleep

def local_time(counter):
    return '| (VECTOR_TIME={}, LOCAL_TIME={})'.format(counter, datetime.now())

def calc_recv_timestamp(recv_time_stamp, counter):
    for id  in range(len(counter)):
        counter[id] = max(recv_time_stamp[id], counter[id])
    return counter

def event(pid, counter):
    counter[pid] += 1
    print('Something happened in {} !'.\
          format(pid) + local_time(counter))
    return counter

def send_message(pipe, pid, counter):
    counter[pid] += 1
    pipe.send(('Empty shell', counter))
    print('Message sent from ' + str(pid) + local_time(counter))
    return counter

def recv_message(pipe, pid, counter):
    counter[pid] += 1
    message, timestamp = pipe.recv()
    counter = calc_recv_timestamp(timestamp, counter)
    print('Message received at ' + str(pid)  + local_time(counter))
    return counter

def report_counter(pid, counter):
    print("="*100 + f"Process {pid} has counter {counter}")

def processA(pipeAB):
    pid = 0
    counter = [0, 0, 0]

    counter = send_message(pipeAB, pid, counter) # a0 -> b0
    counter = send_message(pipeAB, pid, counter) # a1 -> b1
    counter = event(pid, counter)                # a2
    counter = recv_message(pipeAB, pid, counter) # b2 -> a3
    counter = event(pid, counter)                # a4
    counter = event(pid, counter)                # a5
    counter = recv_message(pipeAB, pid, counter) # b5 -> a6 
    
    report_counter(pid, counter)

def processB(pipeBA, pipeBC):
    pid = 1
    counter = [0, 0, 0]

    counter = recv_message(pipeBA, pid, counter) # a0 -> v0
    counter = recv_message(pipeBA, pid, counter) # a1 -> b1
    counter = send_message(pipeBA, pid, counter) # b2 -> a3
    counter = recv_message(pipeBC, pid, counter) # c0 -> b3
    counter = event(pid, counter)                # b4
    counter = send_message(pipeBA, pid, counter) # b5 -> a6
    counter = send_message(pipeBC, pid, counter) # b6 -> c1
    counter = send_message(pipeBC, pid, counter) # b7 -> c3
    
    report_counter(pid, counter)


def processC(pipeCB):
    pid = 2
    counter = [0, 0, 0]

    counter = send_message(pipeCB, pid, counter) # c0 -> b3
    counter = recv_message(pipeCB, pid, counter) # b6 -> c1
    counter = event(pid, counter)                # c2
    counter = recv_message(pipeCB, pid, counter) # b7 -> c3
    
    report_counter(pid, counter)


if __name__ == '__main__':
    AB, BA = Pipe()
    BC, CB = Pipe()

    process1 = Process(target=processA, args=(AB,))
    process2 = Process(target=processB, args=(BA, BC))
    process3 = Process(target=processC, args=(CB,))

    process1.start()
    process2.start()
    process3.start()

    process1.join()
    process2.join()
    process3.join()