itc_d.py

#!/usr/bin/python

#REFERENCES#
__author__ = "Corey M. Farmer - 2011"
__version__ = "1.1"

'''DESCRIPTION: this program is designed to:
1) run as a system process daemon (background process)
2) read given directory for file feeds from ITC (managed by Robie Bennett)
3) parse and write the file contents to a mysql datatable
4) delete file after job completion

Exception Handling:
program errors will be handled via commonfunctionlibrary.buildEmailGen() method
and sent to the system adminMailingList defined in given module.

errors encountered from ITC files will prompt a file rename to 'invError_' + [filename]
and excluded from future directory iterator instances.'''
#END REFERENCES#

import sys, os
sys.path.append( '/home/coreyf/applications/common' )
import commonfunctionlibrary as comfunclib

def checkIfRunning():
    '''This method verifies that an instance of this program is not already running.
    If count of process id`s is greater than 1 close program.'''

    if len( os.popen( "ps -aef | grep -i 'itc_d.py' | grep -v 'grep' | awk '{ print $3 }'" ).read().strip().split( '\n' ) ) > 1:
        raise SystemExit(0)

def createDaemon():
    '''This method sends the itc_d.py program to the command shell background process list;
    freeing up the shell CLI for user input again while the program continues to execute.'''

    try:
        pid = os.fork()
    except OSError, e:
        raise Exception, "%s [%d]" % (e.strerror, e.errno)
    if ( pid == 0 ):
        os.setsid()
        try:
            pid = os.fork()
        except OSError, e:
            raise Exception, "%s [%d]" % (e.strerror, e.errno)
        if ( pid != 0 ): os._exit(0)
    else:
        os._exit(0)

def dirIterate():
    '''iterate over "path" variable location searching for files not including
    files with "invError_" in filename.'''

    for file in os.listdir( path ):
        if 'invError_' in file: continue
        parseContents( file )

def parseContents( file ):
    '''method to parse the contents of individual files, write the data to a mysql table,
    and delete the file after successfully completing previous operations.'''

    global aErrorHandler
    errLevel = 0

    try:
        fopen = open( path + file )
        try:
            contents = fopen.read().split('|')
            if len( contents ) == 8:
                for data in contents:
                       print data
            else:
                errLevel = 2.1
                aErrorHandler.append( {'error': 'empty or missing fields in exploded file content!-> expected 8 fields but found ' + str( len( contents ) ), 'file': file, 'caller': 'parseContents::if errLevel:' + str( errLevel ) } )
        finally:
            fopen.close()
    except IOError, e:
        errLevel = 1.1
            aErrorHandler.append( {'error': e.strerror, 'file': file, 'caller': 'parseContents::try errLevel:' + str( errLevel ) } )

    pfile = path + file
    if os.path.exists( pfile ):
        os.rename( pfile, path + 'invError_' + file )


    if errLevel > 0:
        try:
            pass
        except OSError, e:
            errLevel = 1.2
            aErrorHandler.append( {'error': e.strerror, 'file': file, 'caller': 'parseContents::try errLevel:' + str( errLevel ) } )
        finally: pass


def sendErrorReport():
    '''method designed to handle errors/exceptions encountered within this program
    in a graceful way by notifying the adminMailingList and not raising the system level exception
    (keeping the program from exiting with errors).'''

    aAttach = []
    body = '<strong>Error(s) have occurred within the file (' + __file__ + ' )!</strong><br><br>'
    for index, error in enumerate( aErrorHandler ):
        if len( error['file'] ) > 0: aAttach.append( path + error['file'] )
        body += ( str( index+1 ) + ') <strong>Function Name:</strong> ' + error['caller'] +
                     '<br><strong>File Causing Error:</strong> ' + path + error['file'] +
                     '<br><strong>Error:</strong> ' + error['error'] + '<br><br>' )

    if len( body ) > 0:
        comfunclib.buildEmailGen( 'USLONSWEB003::pyERROR>>' + __file__, 'adminMailingList', body, aAttach )

#begin execution code
path = '/home/coreyf/uslonsweb003/www/systems/txt_test/'

def main():
    aErrorHandler = []

    #SETUP ENVIRONMENT#
    checkIfRunning() #ensure program is not running as another process already
    #createDaemon() #set program as shell background process (daemonize)
    ###################

    dirIterate()

    if len( aErrorHandler ) > 0:
        sendErrorReport()

    raise SystemExit(0)
main()