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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 typing import IO, Any, Callable, Optional
from zope.interface import implementer
from twisted.python.compat import ioType
from ._format import formatEventAsClassicLogText, formatTime, timeFormatRFC3339
from ._interfaces import ILogObserver, LogEvent
@implementer(ILogObserver)
class FileLogObserver:
"""
Log observer that writes to a file-like object.
"""
def __init__(
self, outFile: IO[Any], formatEvent: Callable[[LogEvent], Optional[str]]
) -> None:
"""
@param outFile: A file-like object. Ideally one should be passed which
accepts text data. Otherwise, UTF-8 L{bytes} will be used.
@param formatEvent: A callable that formats an event.
"""
if ioType(outFile) is not str:
self._encoding: Optional[str] = "utf-8"
else:
self._encoding = None
self._outFile = outFile
self.formatEvent = formatEvent
def __call__(self, event: LogEvent) -> None:
"""
Write event to file.
@param event: An event.
"""
text = self.formatEvent(event)
if text:
if self._encoding is None:
self._outFile.write(text)
else:
self._outFile.write(text.encode(self._encoding))
self._outFile.flush()
def textFileLogObserver(
outFile: IO[Any], timeFormat: Optional[str] = timeFormatRFC3339
) -> FileLogObserver:
"""
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 text data. Otherwise, UTF-8 L{bytes} will be used.
@param timeFormat: The format to use when adding timestamp prefixes to
logged events. If L{None}, or for events with no C{"log_timestamp"}
key, the default timestamp prefix of C{"-"} is used.
@return: A file log observer.
"""
def formatEvent(event: LogEvent) -> Optional[str]:
return formatEventAsClassicLogText(
event, formatTime=lambda e: formatTime(e, timeFormat)
)
return FileLogObserver(outFile, formatEvent)
|
