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# -*- test-case-name: twisted.logger.test.test_file -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
File log observer.
"""
from zope.interface import implementer
from twisted.python.compat import ioType, unicode
from ._observer import ILogObserver
from ._format import formatTime
from ._format import timeFormatRFC3339
from ._format import formatEventAsClassicLogText
@implementer(ILogObserver)
class FileLogObserver(object):
"""
Log observer that writes to a file-like object.
"""
def __init__(self, outFile, formatEvent):
"""
@param outFile: A file-like object. Ideally one should be passed which
accepts L{unicode} data. Otherwise, UTF-8 L{bytes} will be used.
@type outFile: L{io.IOBase}
@param formatEvent: A callable that formats an event.
@type formatEvent: L{callable} that takes an C{event} argument and
returns a formatted event as L{unicode}.
"""
if ioType(outFile) is not unicode:
self._encoding = "utf-8"
else:
self._encoding = None
self._outFile = outFile
self.formatEvent = formatEvent
def __call__(self, event):
"""
Write event to file.
@param event: An event.
@type event: L{dict}
"""
text = self.formatEvent(event)
if text is None:
text = u""
if "log_failure" in event:
try:
traceback = event["log_failure"].getTraceback()
except Exception:
traceback = u"(UNABLE TO OBTAIN TRACEBACK FROM EVENT)\n"
text = u"\n".join((text, traceback))
if self._encoding is not None:
text = text.encode(self._encoding)
if text:
self._outFile.write(text)
self._outFile.flush()
def textFileLogObserver(outFile, timeFormat=timeFormatRFC3339):
"""
Create a L{FileLogObserver} that emits text to a specified (writable)
file-like object.
@param outFile: A file-like object. Ideally one should be passed which
accepts L{unicode} data. Otherwise, UTF-8 L{bytes} will be used.
@type outFile: L{io.IOBase}
@param timeFormat: The format to use when adding timestamp prefixes to
logged events. If C{None}, or for events with no C{"log_timestamp"}
key, the default timestamp prefix of C{u"-"} is used.
@type timeFormat: L{unicode} or C{None}
@return: A file log observer.
@rtype: L{FileLogObserver}
"""
def formatEvent(event):
return formatEventAsClassicLogText(
event, formatTime=lambda e: formatTime(e, timeFormat)
)
return FileLogObserver(outFile, formatEvent)
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