#!/usr/bin/python

import os
import time
import sys
import logging
import exceptions
import fcntl

PID_FILE="TCP_RELAY.PID"

def create_pid_file():
    pid = -1
    pid = os.getpid()
    f = open(PID_FILE,'w')
    f.write(str(pid))


def compare_pid(pid):
    PS_CMD = "ps -ef|awk '{print $2}'|grep "
    PS_CMD = PS_CMD + pid

    fd=os.popen(PS_CMD,"r")
    pid_string = fd.read()
    #print(pid_string)
    if pid_string:
        #print(pid_string)
        bRun = 1
        return bRun
    else:
	bRun = 0
        return bRun
    
'''
def single_test():
    bRun = 0
    try:
       fd=open(PID_FILE,'r')

    except IOError:
        print("PID File doesn't exist,create one")
        create_pid_file()
        return bRun
    
          
    if fd:
       old_pid = fd.readline()
       print("already exist pid=%s"%old_pid)
       bRun = compare_pid(old_pid)
       if bRun == 1:
           print("The task is already running")
           print("Exit")
	
       else:
           print("No existing running task")
           print("Continue executing")
           create_pid_file()
       
       
    return bRun
'''
def single_test(): 
    global pidfile 
    pidfile = open(PID_FILE, "w") 
    try: 
        fcntl.lockf(pidfile, fcntl.LOCK_EX | fcntl.LOCK_NB) 
    except IOError: 
        print("The task is already running...")
        sys.exit(0)