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# Copyright (C) 2010, 2012 Google Inc. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import logging
import os
import sys
import time
LOG_HANDLER_NAME = 'MeteredStreamLogHandler'
class MeteredStream(object):
"""
This class implements a stream wrapper that has 'meters' as well as
regular output. A 'meter' is a single line of text that can be erased
and rewritten repeatedly, without producing multiple lines of output. It
can be used to produce effects like progress bars.
"""
@staticmethod
def _erasure(txt):
num_chars = len(txt)
return '\b' * num_chars + ' ' * num_chars + '\b' * num_chars
@staticmethod
def _ensure_newline(txt):
return txt if txt.endswith('\n') else txt + '\n'
def __init__(self, stream=None, verbose=False, logger=None, time_fn=None, pid=None, number_of_columns=None):
self._stream = stream or sys.stderr
self._verbose = verbose
self._time_fn = time_fn or time.time
self._pid = pid or os.getpid()
self._isatty = self._stream.isatty()
self._erasing = self._isatty and not verbose
self._last_partial_line = ''
self._last_write_time = 0.0
self._throttle_delay_in_secs = 0.066 if self._erasing else 10.0
self._number_of_columns = sys.maxint
if self._isatty and number_of_columns:
self._number_of_columns = number_of_columns
self._logger = logger
self._log_handler = None
if self._logger:
log_level = logging.DEBUG if verbose else logging.INFO
self._log_handler = _LogHandler(self)
self._log_handler.setLevel(log_level)
self._logger.addHandler(self._log_handler)
def __del__(self):
self.cleanup()
def cleanup(self):
if self._logger:
self._logger.removeHandler(self._log_handler)
self._log_handler = None
def write_throttled_update(self, txt):
now = self._time_fn()
if now - self._last_write_time >= self._throttle_delay_in_secs:
self.write_update(txt, now)
def write_update(self, txt, now=None):
self.write(txt, now)
if self._erasing:
self._last_partial_line = txt[txt.rfind('\n') + 1:]
def write(self, txt, now=None, pid=None):
now = now or self._time_fn()
pid = pid or self._pid
self._last_write_time = now
if self._last_partial_line:
self._erase_last_partial_line()
if self._verbose:
now_tuple = time.localtime(now)
msg = '%02d:%02d:%02d.%03d %d %s' % (now_tuple.tm_hour, now_tuple.tm_min, now_tuple.tm_sec, int((now * 1000) % 1000), pid, self._ensure_newline(txt))
elif self._isatty:
msg = txt
else:
msg = self._ensure_newline(txt)
self._stream.write(msg)
def writeln(self, txt, now=None, pid=None):
self.write(self._ensure_newline(txt), now, pid)
def _erase_last_partial_line(self):
num_chars = len(self._last_partial_line)
self._stream.write(self._erasure(self._last_partial_line))
self._last_partial_line = ''
def flush(self):
if self._last_partial_line:
self._stream.write('\n')
self._last_partial_line = ''
self._stream.flush()
def number_of_columns(self):
return self._number_of_columns
class _LogHandler(logging.Handler):
def __init__(self, meter):
logging.Handler.__init__(self)
self._meter = meter
self.name = LOG_HANDLER_NAME
def emit(self, record):
self._meter.writeln(record.getMessage(), record.created, record.process)
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