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"""
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A source of IRC log files
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"""
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import codecs
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from datetime import date, datetime, timedelta
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import pytz
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# for SEEK_*, errno
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import os, errno
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class LogSource (object) :
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"""
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A collection of IRC logs for a specific target in some format. Provides the possibility to read specific events
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"""
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def get_latest (self, count) :
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"""
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Yield the latest events, up to `count` of them.
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"""
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abstract
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class LogFile (LogSource) :
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"""
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A file containing LogEvents
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"""
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def __init__ (self, path, charset='utf-8', sep='\n') :
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"""
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Open the file at the given path, which contains data of the given codec, as lines separated by the given separator
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"""
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# store
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self.path = path
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self.charset = charset
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self.sep = sep
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# open
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self.file = codecs.open(path, 'r', charset)
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def __iter__ (self) :
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"""
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Yields a series of lines, as read from the top of the file
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"""
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# seek to beginning
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self.file.seek(0)
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# iterate over lines
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return iter(self.file)
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def get_latest (self, count) :
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"""
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Returns up to <count> lines from the end of the file, or less, if the file doesn't contain that many lines
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"""
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# the list of lines
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lines = []
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# seek to end of file
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self.file.seek(0, os.SEEK_END)
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# read offset
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# XXX; why -2 ?
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offset = self.file.tell() - 2
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# use this blocksize
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BLOCKSIZE = 1024
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# trailing data
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buf = ''
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# read a block at a time, backwards
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while count > 0 and offset >= 0:
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# update offset
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offset -= BLOCKSIZE
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# normalize to zero
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if offset < 0 :
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offset = 0
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# seek backwards one block
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self.file.seek(offset)
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# add the new block to our buffer
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read_buf = self.file.read(BLOCKSIZE)
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# make sure we got the right amount of data
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assert len(read_buf) == BLOCKSIZE, "read(%d) -> %d" % (BLOCKSIZE, len(read_buf))
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# add in our previous buf
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buf = read_buf + buf
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# split out lines
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buf_lines = buf.split(self.sep)
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# keep the first one as our buffer, as it's incomplete
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buf = buf_lines[0]
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# add up to count lines to our lines buffer
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lines = buf_lines[1:count + 1] + lines
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# update count
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count -= (len(buf_lines) - 1)
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# return the line list
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return lines
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class LogDirectory (LogSource) :
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"""
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A directory containing a series of timestamped LogFiles
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"""
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def __init__ (self, path, tz, charset='utf-8', filename_fmt='%Y-%m-%d') :
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"""
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Load the logfiles at the given path.
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The files contain data in the given charset, and are named according the the date in the given timezone and
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date format.
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"""
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# store
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self.path = path
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self.tz = tz
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self.charset = charset
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self.filename_fmt = filename_fmt
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def _get_logfile_datetime (self, dt) :
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"""
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Get the logfile corresponding to the given datetime
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"""
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# convert to target timezone
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dtz = dt.astimezone(self.tz)
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# convert to date and use that
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return self._get_logfile_date(dtz.date())
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def _get_logfile_date (self, d) :
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"""
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Get the logfile corresponding to the given naive date in our timezone
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"""
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# format filename
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filename = d.strftime(self.filename_fmt)
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# build path
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path = os.path.join(self.path, filename)
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# return the LogFile
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return LogFile(path, self.charset)
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def _iter_backwards (self, dt=None) :
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"""
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Yields an infinite series of naive date objects in our timezone, iterating backwards in time starting at the
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given *datetime*, or the the current date, if none given
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"""
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# default to now
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if not dt :
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dt = datetime.now(pytz.utc)
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# convert to target timezone
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dtz = dt.astimezone(self.tz)
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# our timedelta
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ONE_DAY = timedelta(1)
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# iterate unto infinity
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while True :
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# yield
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yield dtz.date()
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# one day sdrawkcab
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dtz -= ONE_DAY
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def get_latest (self, count) :
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"""
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Uses _iter_backwards + _get_logfile_date to read the yield the given lines from as many logfiles as needed
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"""
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# iterate backwards from now
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day_iter = self._iter_backwards()
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# number of files read
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files = 0
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# only read up to 100 files or so
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MAX_FILES = 100
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# loop until done
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while count > 0 :
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logfile = None
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try :
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# get next logfile
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files += 1
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# open
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logfile = self._get_logfile_date(day_iter.next())
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except IOError, e :
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# skip nonexistant days if we haven't found any logs yet
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if e.errno != errno.ENOENT :
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raise
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if files > MAX_FILES :
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raise Exception("No recent logfiles found")
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else :
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# skip to next day
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continue
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# yield lines
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for line in logfile.get_latest(count) :
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# yield while we still need to, otherwise, stop
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if count > 0 :
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# decrement
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count -= 1
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yield line
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else :
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break
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