#!/usr/bin/env python

import sys, os, commands, string, getopt, glob, time



def ts():
	rt = time.strftime("%Y/%m/%d %H:%M:%S", time.localtime( time.time() ))
	rt = rt + " = "

	return rt



# period	the period of time in second which you want to check whether the file is out of date
# file		the file you want to check
# cmd		when the file is out of date, execute this cmd
# timeout	the time which you think the file is out of date
# lines		the lines in the end of the file you want to print
try:
	optlist, args = getopt.getopt(sys.argv[1:], 'p:f:c:t:l:g:',
		 ['period=', 'file=', 'cmd=', 'timeout=', 'lines=', 'globalTimeout=' ])
except getopt.GetoptError, e:
	print 'WatchDog: argument error'
	sys.stdout.flush()
	sys.exit(1)



period = 120
file = ''
cmd = ''
timeout = 0
globalTimeout = 1000000   # sec allowed to run in total
lines = 30
for key, val in optlist:
	if key == '--file':
		file = val
	elif key == '-f':
		file = val
	elif key == '--period':
		period = int(val)
	elif key == '-p':
		period = int(val)
	elif key == '--timeout':
		timeout = int(val)
	elif key == '-t':
		timeout = int(val)
	elif key == '--globalTimeout':
		globalTimeout = int(val)
	elif key == '-g':
		globalTimeout = int(val)
	elif key == '--cmd':
		cmd = val
	elif key == '-c':
		cmd = val
	elif key == '--lines':
		lines = int(val)
	elif key == '-l':
		lines = int(val)



if file == '' or os.path.exists( file ) == 0:
	print ts() + 'WatchDog: no file assigned or file is not existent.'
	sys.stdout.flush()
	sys.exit(1)


if timeout == 0:
	print ts() + 'WatchDog: no timeout assigned.'
	sys.stdout.flush()
	sys.exit(1)


if cmd == '':
	print ts() + 'WatchDog: no cmd assigned.'
	sys.stdout.flush()
	sys.exit(1)



pid = os.fork()

# parent
if pid != 0:
	print ts() + 'WatchDog: fork a child process %d to monitor %s' % (pid, file)
	print ts() + 'WatchDog parameters:'
	print '          period        = ',period
	print '          cmd           = ',cmd
	print '          timeout       = ',timeout
	print '          globalTimeout = ',globalTimeout
	print '          lines         = ',lines

	#os.system( 'echo %d > WatchDog.pid' % pid )
	sys.stdout.flush()
	sys.exit(0)



# child
pid = os.getpid()
print ts() + 'WatchDog: Child process %d is monitoring %s' % (pid, file)

globalT0 = int( time.time() )

while 1:
	# file is gone
	if os.path.exists( file ) == 0:
		break


	stat = os.stat( file )
	LastUpdateTime = stat[8]

	now = int( time.time() )
	dt0 = now - LastUpdateTime
	dt1 = now - globalT0
	if ( dt0 > timeout or dt1 > globalTimeout ) :
		c = 'tail -n %d %s' % (lines, file)
		s, r = commands.getstatusoutput( c )
		print ts() + '> %s' % c
		print ts() + '%s' % r
		print ''

		if ( dt0 > timeout  ) :
		    LastUpdateTime = time.strftime("%Y/%m/%d %H:%M:%S", time.localtime( LastUpdateTime ))
		    print ts() + 'WatchDog: File %s is not updated more than %d since %s' % (file, timeout, LastUpdateTime)
		else:
		    nowStr = time.strftime("%Y/%m/%d %H:%M:%S", time.localtime( now ) )
		    sttStr = time.strftime("%Y/%m/%d %H:%M:%S", time.localtime( globalT0 ) )
		    print ts() + 'WatchDog: Exceeded global timeout of %d s, start=%s, now=%s' % (globalTimeout, sttStr ,nowStr)

		s, r = commands.getstatusoutput( cmd )
		print ts() + '> %s' % cmd
		print ts() + '%s' % r
		print ''

		sys.stdout.flush()

		break

	os.system( 'sleep %d' % period )



sys.stdout.flush()
sys.exit(0)