Sometime I want extract part of disk-based log file, created by standard logging module) into separated file on disk. This recipe shows simple technique to acquire this.
Sample: processing tasks in loop, so on exit I have few logs: on log per task.
Python, 114 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | # -*- coding: Windows-1251 -*-
'''
'''
import logging
import os
log=logging.getLogger('LogExtractor')
BUF_SIZE=8*1024
class LogExtractor(object):
'''
Save current position of first disk file-based handler
and save log fragment up to current position
into separated file by request.
Useful for splitting common program log for further reviewing
by unprofessional personnel/client ;)
'''
def _find_file_handler(self, logger):
# partially imported from Logger.callHandlers()
c = logger
filehandler=None
while c:
for hdlr in c.handlers:
#log.info('Handler: %s' % type(hdlr))
if isinstance(hdlr, logging.FileHandler):
filehandler=hdlr
break
if filehandler:
break
if not c.propagate:
c = None #break out
else:
c = c.parent
return filehandler
def __init__(self, logger):
'''
search for first FileHandler and store it's current position
'''
self.init_ok=0
if not isinstance(logger, logging.Logger):
log.error('__init__: <logger> must be instance of logging.Logger')
return
filehandler=self._find_file_handler(logger)
if filehandler is None:
log.error('__init__: no FileHandlers binded to <logger>')
return
self.stream=filehandler.stream
self.basename=filehandler.baseFilename
self.start_pos=self.stream.tell()
self.init_ok=1
def write_part(self, part_filename):
'''
put log file fragment from saved position to cyurrent state
into separate file
'''
if not self.init_ok:
log.error('not properly initialized')
return 0
if self.stream.closed:
if os.path.isfile(self.basename):
part_size=os.path.getsize()
else:
log.error('log file (%s) not found on disk' % (self.basename))
return 0
else:
part_size=self.stream.tell() - self.start_pos
# put fragment
f_log=open(self.basename, 'rb')
f_part=open(part_filename, 'wb')
try:
f_log.seek(self.start_pos)
left_size=part_size
while left_size > 0:
s=min(left_size, BUF_SIZE)
buf=f_log.read(s)
if len(buf) > 0:
f_part.write(buf)
left_size-=s
else:
break
return 1
finally:
f_part.close()
f_log.close()
return 0
if __name__ == '__main__':
import sys
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(levelname)s %(message)s',
filename='%s.log' % sys.argv[0],
filemode='w')
log=logging.getLogger('main')
for i in range(1, 6):
logextr=LogExtractor(log) # save current position
for r in range(10):
log.info('Pass %d: log message %d' % (i, r))
rc=logextr.write_part('pass_%d.log' % i) # put fragment to file
log.info('write_part result: %r' % rc)
|
Tags: sysadmin
