Show a pretty progressbar when uploading and downloading an image.

Add a new module that contain generic wrapper for file and iterator, which
are used to wrap image to upload and the request body iterator in upload and
download cases repectively, to show and advance a pretty progress bar when this
laters are consumed, The progress bar is triggered by adding a --progress command
line argument to commands: image-create, image-download or image-update.

Change-Id: I2ba42fd0c58f4fa087adb568ec3f08246cae3759
bug fix: LP#1112309
blueprint: progressbar-when-uploading

1 files changed, 87 insertions, 0 deletions

diff --git a/glanceclient/common/progressbar.py b/glanceclient/common/progressbar.py
new file mode 100644
index 0000000..63d4d8d
--- /dev/null
+++ b/glanceclient/common/progressbar.py
@@ -0,0 +1,87 @@
+# Copyright 2013 OpenStack LLC.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import sys
+
+
+class _ProgressBarBase(object):
+    """
+    Base abstract class used by specific class wrapper to show a progress bar
+    when the wrapped object are consumed.
+
+    :param wrapped: Object to wrap that hold data to be consumed.
+    :param totalsize: The total size of the data in the wrapped object.
+
+    :note: The progress will be displayed only if sys.stdout is a tty.
+    """
+
+    def __init__(self, wrapped, totalsize):
+        self._wrapped = wrapped
+        self._totalsize = float(totalsize)
+        self._show_progress = sys.stdout.isatty() and self._totalsize != 0
+        self._percent = 0
+
+    def _display_progress_bar(self, size_read):
+        if self._show_progress:
+            self._percent += size_read / self._totalsize
+            # Output something like this: [==========>             ] 49%
+            sys.stdout.write('\r[{0:<30}] {1:.0%}'.format(
+                '=' * int(round(self._percent * 29)) + '>', self._percent
+            ))
+            sys.stdout.flush()
+
+    def __getattr__(self, attr):
+        # Forward other attribute access to the wrapped object.
+        return getattr(self._wrapped, attr)
+
+
+class VerboseFileWrapper(_ProgressBarBase):
+    """
+    A file wrapper that show and advance a progress bar whenever file's read
+    method is called.
+    """
+
+    def read(self, *args, **kwargs):
+        data = self._wrapped.read(*args, **kwargs)
+        if data:
+            self._display_progress_bar(len(data))
+        else:
+            # Break to a new line from the progress bar for incoming output.
+            sys.stdout.write('\n')
+        return data
+
+
+class VerboseIteratorWrapper(_ProgressBarBase):
+    """
+    An iterator wrapper that show and advance a progress bar whenever
+    data is consumed from the iterator.
+
+    :note: Use only with iterator that yield strings.
+    """
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        try:
+            data = self._wrapped.next()
+            # NOTE(mouad): Assuming that data is a string b/c otherwise calling
+            # len function will not make any sense.
+            self._display_progress_bar(len(data))
+            return data
+        except StopIteration:
+            # Break to a new line from the progress bar for incoming output.
+            sys.stdout.write('\n')
+            raise