Source code for b2sdk.progress

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#
# File: b2sdk/progress.py
#
# Copyright 2019 Backblaze Inc. All Rights Reserved.
#
# License https://www.backblaze.com/using_b2_code.html
#
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from __future__ import annotations

import time
from abc import ABCMeta, abstractmethod

try:
    from tqdm import tqdm  # displays a nice progress bar
except ImportError:
    tqdm = None  # noqa


[docs]class AbstractProgressListener(metaclass=ABCMeta): """ Interface expected by B2Api upload and download methods to report on progress. This interface just accepts the number of bytes transferred so far. Subclasses will need to know the total size if they want to report a percent done. """ def __init__(self, description: str = ''): self.description = description self._closed = False
[docs] @abstractmethod def set_total_bytes(self, total_byte_count: int) -> None: """ Always called before __enter__ to set the expected total number of bytes. May be called more than once if an upload is retried. :param total_byte_count: expected total number of bytes """
[docs] @abstractmethod def bytes_completed(self, byte_count: int) -> None: """ Report the given number of bytes that have been transferred so far. This is not a delta, it is the total number of bytes transferred so far. Transfer can fail and restart from the beginning, so byte count can decrease between calls. :param byte_count: number of bytes have been transferred """
def _can_change_description(self) -> bool: """ Determines, on a per-implementation basis, whether the description can be changed at this time. """ return True
[docs] def change_description(self, new_description: str) -> bool: """ Ability to change the description after the listener is started. Note: whether the change of description is allowed depends on the implementation. The safest option is to change the description before setting the total bytes. :param new_description: the new description to be used :return: information whether the description was changed """ if not self._can_change_description(): return False self.description = new_description return True
[docs] def close(self) -> None: """ Must be called when you're done with the listener. In well-structured code, should be called only once. """ #import traceback, sys; traceback.print_stack(file=sys.stdout) assert self._closed is False, 'progress listener was closed twice! uncomment the line above to debug this' self._closed = True
def __enter__(self): """ A standard context manager method. """ return self def __exit__(self, exc_type, exc_val, exc_tb): """ A standard context manager method. """ self.close()
[docs]class TqdmProgressListener(AbstractProgressListener): """ Progress listener based on tqdm library. """ def __init__(self, *args, **kwargs): self.tqdm = None # set in set_total_bytes() self.prev_value = 0 super().__init__(*args, **kwargs) def set_total_bytes(self, total_byte_count: int) -> None: if self.tqdm is None: self.tqdm = tqdm( desc=self.description, total=total_byte_count, unit='B', unit_scale=True, leave=True, miniters=1, smoothing=0.1, mininterval=0.2, ) def bytes_completed(self, byte_count: int) -> None: # tqdm doesn't support running the progress bar backwards, # so on an upload retry, it just won't move until it gets # past the point where it failed. if self.prev_value < byte_count: self.tqdm.update(byte_count - self.prev_value) self.prev_value = byte_count def _can_change_description(self) -> bool: return self.tqdm is None def close(self) -> None: if self.tqdm is not None: self.tqdm.close() super().close()
[docs]class SimpleProgressListener(AbstractProgressListener): """ Just a simple progress listener which prints info on a console. """ def __init__(self, *args, **kwargs): self.complete = 0 self.last_time = time.time() self.any_printed = False self.total = 0 # set in set_total_bytes() super().__init__(*args, **kwargs) def set_total_bytes(self, total_byte_count: int) -> None: self.total = total_byte_count def bytes_completed(self, byte_count: int) -> None: now = time.time() elapsed = now - self.last_time if 3 <= elapsed and self.total != 0: if not self.any_printed: print(self.description) print(' %d%%' % int(100.0 * byte_count / self.total)) self.last_time = now self.any_printed = True def _can_change_description(self) -> bool: return not self.any_printed def close(self) -> None: if self.any_printed: print(' DONE.') super().close()
[docs]class DoNothingProgressListener(AbstractProgressListener): """ This listener gives no output whatsoever. """ def set_total_bytes(self, total_byte_count: int) -> None: pass def bytes_completed(self, byte_count: int) -> None: pass
[docs]class ProgressListenerForTest(AbstractProgressListener): """ Capture all the calls so they can be checked. """ def __init__(self, *args, **kwargs): self.calls = [] super().__init__(*args, **kwargs) def set_total_bytes(self, total_byte_count: int) -> None: self.calls.append('set_total_bytes(%d)' % (total_byte_count,)) def bytes_completed(self, byte_count: int) -> None: self.calls.append('bytes_completed(%d)' % (byte_count,)) def close(self) -> None: self.calls.append('close()') super().close() def get_calls(self) -> list[str]: return self.calls
[docs]def make_progress_listener(description: str, quiet: bool) -> AbstractProgressListener: """ Return a progress listener object depending on some conditions. :param description: listener description :param quiet: if ``True``, do not output anything :return: a listener object """ if quiet: return DoNothingProgressListener() elif tqdm is not None: return TqdmProgressListener(description) else: return SimpleProgressListener(description)