68 lines
2.3 KiB
Python
68 lines
2.3 KiB
Python
# Copyright 2013 OpenStack Foundation
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import sys
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class _ProgressBarBase(object):
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"""A progress bar provider for a wrapped object.
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Base abstract class used by specific class wrapper to show
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a progress bar when the wrapped object are consumed.
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:param wrapped: Object to wrap that hold data to be consumed.
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:param totalsize: The total size of the data in the wrapped object.
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:note: The progress will be displayed only if sys.stdout is a tty.
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"""
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def __init__(self, wrapped, totalsize):
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self._wrapped = wrapped
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self._totalsize = float(totalsize)
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self._show_progress = sys.stdout.isatty() and self._totalsize != 0
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self._percent = 0
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def _display_progress_bar(self, size_read):
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if self._show_progress:
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self._percent += size_read / self._totalsize
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# Output something like this: [==========> ] 49%
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sys.stdout.write('\r[{0:<30}] {1:.0%}'.format(
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'=' * int(round(self._percent * 29)) + '>', self._percent
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))
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sys.stdout.flush()
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def __getattr__(self, attr):
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# Forward other attribute access to the wrapped object.
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return getattr(self._wrapped, attr)
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class VerboseFileWrapper(_ProgressBarBase):
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"""A file wrapper with a progress bar.
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The file wrapper shows and advances a progress bar whenever the
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wrapped file's read method is called.
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"""
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def read(self, *args, **kwargs):
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data = self._wrapped.read(*args, **kwargs)
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if data:
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self._display_progress_bar(len(data))
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else:
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if self._show_progress:
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# Break to a new line from the progress bar for incoming
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# output.
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sys.stdout.write('\n')
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return data
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