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tail.py
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tail.py
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# Twisted FollowTail
# Mohit Muthanna
#
# A Twisted version of POE::Wheel::FollowTail. Adapted from
# a post by Kragen Sitaker on the Kragen-hacks mailing list.
#
# http://lists.canonical.org/pipermail/kragen-hacks/2005-June/000413.html
from twisted.internet import reactor
from twisted.protocols import basic
import os, stat
class FollowTail:
from os import linesep as newline
__line_buffer = ""
def __init__( self, filename = None, seekend = True, delay = 1 ):
self.filename = filename
self.delay = delay
self.seekend = seekend
self.keeprunning = False
def fileIdentity( self, struct_stat ):
return struct_stat[stat.ST_DEV], struct_stat[stat.ST_INO]
def start( self ):
self.keeprunning = True
self.followTail()
def stop( self ):
self.keeprunning = False
def followTail( self, fileobj = None, fstat = None ):
if fileobj is None:
fileobj = open( self.filename )
if self.seekend: fileobj.seek( 0, 2 )
line = fileobj.read()
if line: self.dataReceived( line )
if fstat is None: fstat = os.fstat( fileobj.fileno() )
try: stat = os.stat( self.filename )
except: stat = fstat
if self.fileIdentity( stat ) != self.fileIdentity( fstat ):
fileobj = open( self.filename )
fstat = os.fstat( fileobj.fileno() )
self.fileReset()
if self.keeprunning:
reactor.callLater( self.delay, lambda: self.followTail( fileobj, fstat ) )
def dataReceived( self, data ):
# Fill buffer
self.__line_buffer += data
# Split lines
lines = self.__line_buffer.splitlines()
if not data.endswith( self.newline ):
self.__line_buffer = lines.pop()
else:
self.__line_buffer = ""
for line in lines:
self.lineReceived( line )
def lineReceived( self, line ):
"""Override This"""
def fileReset( self ):
"""Override This"""