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| 1 | +# Copyright 2013 OpenStack Foundation |
| 2 | +# All Rights Reserved. |
| 3 | +# |
| 4 | +# Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 5 | +# not use this file except in compliance with the License. You may obtain |
| 6 | +# a copy of the License at |
| 7 | +# |
| 8 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +# |
| 10 | +# Unless required by applicable law or agreed to in writing, software |
| 11 | +# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 12 | +# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| 13 | +# License for the specific language governing permissions and limitations |
| 14 | +# under the License. |
| 15 | + |
| 16 | +import sys |
| 17 | + |
| 18 | + |
| 19 | +class _ProgressBarBase(object): |
| 20 | + """A progress bar provider for a wrapped obect. |
| 21 | +
|
| 22 | + Base abstract class used by specific class wrapper to show |
| 23 | + a progress bar when the wrapped object are consumed. |
| 24 | +
|
| 25 | + :param wrapped: Object to wrap that hold data to be consumed. |
| 26 | + :param totalsize: The total size of the data in the wrapped object. |
| 27 | +
|
| 28 | + :note: The progress will be displayed only if sys.stdout is a tty. |
| 29 | + """ |
| 30 | + |
| 31 | + def __init__(self, wrapped, totalsize): |
| 32 | + self._wrapped = wrapped |
| 33 | + self._totalsize = float(totalsize) |
| 34 | + self._show_progress = sys.stdout.isatty() and self._totalsize != 0 |
| 35 | + self._percent = 0 |
| 36 | + |
| 37 | + def _display_progress_bar(self, size_read): |
| 38 | + if self._show_progress: |
| 39 | + self._percent += size_read / self._totalsize |
| 40 | + # Output something like this: [==========> ] 49% |
| 41 | + sys.stdout.write('\r[{0:<30}] {1:.0%}'.format( |
| 42 | + '=' * int(round(self._percent * 29)) + '>', self._percent |
| 43 | + )) |
| 44 | + sys.stdout.flush() |
| 45 | + |
| 46 | + def __getattr__(self, attr): |
| 47 | + # Forward other attribute access to the wrapped object. |
| 48 | + return getattr(self._wrapped, attr) |
| 49 | + |
| 50 | + |
| 51 | +class VerboseFileWrapper(_ProgressBarBase): |
| 52 | + """A file wrapper with a progress bar. |
| 53 | +
|
| 54 | + The file wrapper shows and advances a progress bar whenever the |
| 55 | + wrapped file's read method is called. |
| 56 | + """ |
| 57 | + |
| 58 | + def read(self, *args, **kwargs): |
| 59 | + data = self._wrapped.read(*args, **kwargs) |
| 60 | + if data: |
| 61 | + self._display_progress_bar(len(data)) |
| 62 | + else: |
| 63 | + if self._show_progress: |
| 64 | + # Break to a new line from the progress bar for incoming |
| 65 | + # output. |
| 66 | + sys.stdout.write('\n') |
| 67 | + return data |
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