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# Back In Time
# Copyright (C) 2008-2009 Oprea Dan, Bart de Koning, Richard Bailey
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
import os
import os.path
import time
#class used to handle one application instance mechanism
class GUIApplicationInstance:
#specify the base for control files
def __init__( self, base_control_file, raise_cmd = '' ):
self.pid_file = base_control_file + '.pid'
self.raise_file = base_control_file + '.raise'
self.raise_cmd = raise_cmd
#remove raise_file is already exists
try:
os.remove( self.raise_file )
except:
pass
self.check( raise_cmd )
self.start_application()
#check if the current application is already running
def check( self, raise_cmd ):
#check if the pidfile exists
if not os.path.isfile( self.pid_file ):
return
#read the pid from the file
pid = 0
try:
file = open( self.pid_file, 'rt' )
data = file.read()
file.close()
pid = int( data )
except:
pass
#check if the process with specified by pid exists
if 0 == pid:
return
try:
os.kill( pid, 0 ) #this will raise an exception if the pid is not valid
except:
return
#exit the application
print "The application is already running ! (pid: %s)" % pid
#notify raise
try:
file = open( self.raise_file, 'wt' )
file.write( raise_cmd )
file.close()
except:
pass
exit(0) #exit raise an exception so don't put it in a try/except block
#called when the single instance starts to save it's pid
def start_application( self ):
file = open( self.pid_file, 'wt' )
file.write( str( os.getpid() ) )
file.close()
#called when the single instance exit ( remove pid file )
def exit_application( self ):
try:
os.remove( self.pid_file )
except:
pass
#check if the application must to be raised
#return None if no raise needed, or a string command to raise
def raise_command( self ):
ret_val = None
try:
if os.path.isfile( self.raise_file ):
file = open( self.raise_file, 'rt' )
ret_val = file.read()
file.close()
os.remove( self.raise_file )
except:
pass
return ret_val
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