# L-33 MCS 275 Mon 5 Apr 2010 : clockforkserver.py

# Illustration of a forking server.
# Each requests spawns a process.

# The server will send the time to clients.

import os, sys
from socket import *
from time import ctime, sleep

hostname = ''
port = 12091
buffer = 25

server_address = (hostname,port)
server = socket(AF_INET, SOCK_STREAM)
server.bind(server_address)

server.listen(5) # allow 5 connections

active_processes = []
def kill_processes():
   """
   kills handler processes
   """
   while len(active_processes) > 0:
      pid = active_processes.pop(0)
      print '-> killing process %d' % pid
      os.system('kill -9 %d' % pid)

def handle_client(s):
   """
   handling a client via the socket s
   """
   print "client is blocked for ten seconds ..."
   sleep(10)
   print "handling a client ..."
   while True:
      data = s.recv(buffer)
      if not data: break
      print 'received \"' + data + '\" from client'
      now = ctime()
      print 'sending \"' + now + '\" to client'
      s.send(now)
   s.close()
   os._exit(0)

def dispatcher():
   """
   listen for connecting clients
   """
   try:
      print 'press ctrl c to stop server'
      while True:
         client, address = server.accept()
         print 'server connected at', address
         child_pid = os.fork()
         if child_pid == 0:
            handle_client(client)
         else:
            print 'appending PID', child_pid
            active_processes.append(child_pid)
   except:
      print 'ctrl c pressed, closing server'
      print 'active processes :', active_processes
      kill_processes()
      server.close()

dispatcher()