#coding=utf-8

#myTools.py

import daemon

import fcntl

import time

import sys

import os

class myTools:

    def __init__(self,vPwd,isSingle = True,fLog = None):

        self.isSingle = isSingle

        self.pid = os.getpid()

        if(fLog == None):

            self.fLog = "%s/%s" % (vPwd,self.getLogFile())

        else:

            self.fLog = fLog

        try:

            self.fs = open(self.fLog,'a+')

        except Exception as e:

            print("open file '%s' error:%s" % (self.fLog,str(e)))

    def Log(self,s):

        try:

            self.fs.write("%s pid:%d %s\n" % (time.ctime(),self.pid,s))

            self.fs.flush()

        except Exception as e:

            print("write file error:"+str(e))

    def getLogFile(self,):

        selfFile = sys.argv[0]

        if(selfFile[-3:].upper() == ".PY"):

            selfFile = selfFile[0:-3]

        tmpStr = selfFile[::-1]#reverse string

        slashPos = tmpStr.find("/")#find the 1st "/"

        if(slashPos == -1):

            slashPos = None

        tmpStr = tmpStr[0:slashPos]

        logFile = "%s.log" % tmpStr[::-1]

        return logFile

    def existsInstance(self,):

        if(self.isSingle):

            try:

                fcntl.flock(self.fs.fileno(),fcntl.LOCK_EX | fcntl.LOCK_NB)

                return False

            except Exception as e:

                #self.Log(str(e))

                return True

        else:

            return False

    def __del__(self,):

        try:

            self.fs.close()

        except:

            pass

if __name__ == "__main__":

    vPwd = os.getcwd()

    with daemon.DaemonContext():

        tl = myTools(vPwd)

        if(tl.existsInstance()):

            tl.Log('script is exists and exit')

            exit(0)

        tl.Log('script is started to dong something')

        time.sleep(20)

        tl.Log('script is ended')