szha commented on a change in pull request #9671: Exp backoff for downloads. URL: https://github.com/apache/incubator-mxnet/pull/9671#discussion_r165807962
########## File path: python/mxnet/utils.py ########## @@ -0,0 +1,151 @@ +# Licensed to the Apache Software Foundation (ASF) under one +# or more contributor license agreements. See the NOTICE file +# distributed with this work for additional information +# regarding copyright ownership. The ASF licenses this file +# to you 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. + +"""Utility functions applicable to all areas of code (tests, tutorials, gluon, etc).""" + +__all__ = ['check_sha1', 'download', 'create_dir'] + +import errno +import logging +import time +import os +import hashlib + +try: + import requests +except ImportError: + class requests_failed_to_import(object): + pass + requests = requests_failed_to_import + + +def check_sha1(filename, sha1_hash): + """Check whether the sha1 hash of the file content matches the expected hash. + + Parameters + ---------- + filename : str + Path to the file. + sha1_hash : str + Expected sha1 hash in hexadecimal digits. + + Returns + ------- + bool + Whether the file content matches the expected hash. + """ + sha1 = hashlib.sha1() + with open(filename, 'rb') as f: + while True: + data = f.read(1048576) + if not data: + break + sha1.update(data) + + return sha1.hexdigest() == sha1_hash + + +def _download_retry_with_backoff(fname, url, max_attempts=4): + """Downloads a url with backoff applied, automatically re-requesting after a failure. + :param fname : str + Name of the target file being downloaded. + :param url : str + URL to download. + :param max_attempts : int, optional + The number of requests to attempt before throwing a RequestException. + :return: + A streaming request object. + """ + attempts = 1 + backoff_coef = 50.0 + while True: + try: + print('Downloading %s from %s...' % (fname, url)) + r = requests.get(url, stream=True) + + # If the remote server returned an error, raise a descriptive HTTPError. + # For non-error http codes (e.g. 200, 206) do nothing. + r.raise_for_status() + return r + except requests.exceptions.RequestException: + # Likely non-2** result, possibly timeout or redirection failure. + attempts = attempts + 1 + if attempts > max_attempts: + print('Downloading %s from %s, failed after #%d attempts' % (fname, url, attempts)) + raise + + # Apply backoff with default values borrowed from the popular Boto3 lib. + time.sleep((backoff_coef * (2 ** attempts)) / 1000.0) + + +def download(url, path=None, overwrite=False, sha1_hash=None): + """Download a given URL + + Parameters + ---------- + url : str + URL to download + path : str, optional + Destination path to store downloaded file. By default stores to the + current directory with same name as in url. + overwrite : bool, optional + Whether to overwrite destination file if already exists. + sha1_hash : str, optional + Expected sha1 hash in hexadecimal digits. Will ignore existing file when hash is specified + but doesn't match. + + Returns + ------- + str + The file path of the downloaded file. + """ + if path is None: + fname = url.split('/')[-1] + elif os.path.isdir(path): + fname = os.path.join(path, url.split('/')[-1]) + else: + fname = path + + if overwrite or not os.path.exists(fname) or (sha1_hash and not check_sha1(fname, sha1_hash)): + dirname = os.path.dirname(os.path.abspath(os.path.expanduser(fname))) + if not os.path.exists(dirname): Review comment: that's py3 feature. https://docs.python.org/2.7/library/os.html#os.makedirs ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
