111 lines
3.3 KiB
Python
111 lines
3.3 KiB
Python
"""See `StreamLogger`.
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This is taken from https://gist.github.com/pmuller/2376336
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which has no license associated with it.
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"""
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from __future__ import annotations
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import sys
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import logging
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import io
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from typing import Any, Optional, Tuple
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class StreamLogger:
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"""
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A helper which intercepts what's written to an output stream
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then sends it, line by line, to a `logging.Logger` instance.
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Usage:
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By overwriting `sys.stdout`:
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sys.stdout = StreamLogger('stdout')
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print 'foo'
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As a context manager:
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with StreamLogger('stdout'):
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print 'foo'
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"""
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__name: str
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__stream: Any
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__logger: Optional[logging.Logger]
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__buffer: io.StringIO
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__unbuffered: bool
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__flush_on_new_line: bool
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def __init__(
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self,
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name: str,
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logger: Optional[logging.Logger] = None,
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unbuffered: bool = False,
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flush_on_new_line: bool = True,
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) -> None:
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"""
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``name``: The stream name to incercept ('stdout' or 'stderr')
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``logger``: The logger that will receive what's written to the stream.
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``unbuffered``: If `True`, `.flush()` will be called each time
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`.write()` is called.
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``flush_on_new_line``: If `True`, `.flush()` will be called each time
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`.write()` is called with data containing a
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new line character.
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"""
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self.__name = name
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self.__stream = getattr(sys, name)
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self.__logger = logger or logging.getLogger()
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self.__buffer = io.StringIO()
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self.__unbuffered = unbuffered
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self.__flush_on_new_line = flush_on_new_line
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def write(self, data: str) -> None:
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"""Write data to the stream."""
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self.__buffer.write(data)
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if self.__unbuffered is True or (
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self.__flush_on_new_line is True and "\n" in data
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):
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self.flush()
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def flush(self) -> None:
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"""Flush the stream."""
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self.__buffer.seek(0)
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while True:
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line = self.__buffer.readline()
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if line:
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if line[-1] == "\n":
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line = line[:-1]
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if line:
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level, line = self.parse(line)
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logger = getattr(self.__logger, level)
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logger(line)
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else:
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self.__buffer.seek(0)
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self.__buffer.write(line)
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self.__buffer.truncate()
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break
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else:
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self.__buffer.seek(0)
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self.__buffer.truncate()
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break
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def parse(self, data: str) -> Tuple[str, str]:
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"""Override me!"""
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return "debug", data
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def isatty(self) -> bool:
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"""I'm not a tty."""
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return False
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def __enter__(self) -> None:
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"""Enter the context manager."""
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setattr(sys, self.__name, self)
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def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> None:
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"""Leave the context manager."""
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setattr(sys, self.__name, self.__stream)
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class InfoStreamLogger(StreamLogger):
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"""StreamLogger, but write to info log instead of debug."""
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def parse(self, data: str) -> Tuple[str, str]:
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return "info", data
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