Files
glazier/lib/cache.py
2019-03-19 15:00:47 -04:00

87 lines
2.5 KiB
Python

# Copyright 2016 Google Inc. 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.
"""Manages the on-disk build cache."""
import os
import re
from glazier.lib import download
DNLD_RE = re.compile(r'([@|#][\S]+)')
class CacheError(Exception):
pass
class Cache(object):
"""Handles interation with the on-disk build cache."""
def __init__(self):
self._downloader = download.Download(show_progress=False)
def _DestinationPath(self, cache_path, url):
"""Determines the local path for a file being downloaded.
Args:
cache_path: Path to the local build cache
url: A web address to a file as a string
Returns:
The local disk path as a string.
"""
file_name = url.split('/').pop()
destination = os.path.join(cache_path, file_name)
return destination
def _FindDownload(self, line):
"""Searches a command line for any download strings.
Args:
line: the command line to search
Returns:
the url which requires downloading or none
"""
result = DNLD_RE.search(line)
if result:
return result.group(1).rstrip('"\'')
return None
def CacheFromLine(self, line, build_info):
"""Downloads any files in the command line and replaces with the local path.
Args:
line: the command line to process as a string
build_info: the current build information
Returns:
the final command line as a string; None on error
Raises:
CacheError: unable to download a file to the local cache
"""
match = self._FindDownload(line)
while match:
dl = download.Transform(match, build_info)
destination = self._DestinationPath(build_info.CachePath(), dl)
try:
self._downloader.DownloadFile(dl, destination)
except download.DownloadError as e:
self._downloader.PrintDebugInfo()
raise CacheError('Unable to download required file %s: %s' % (dl, e))
line = line.replace(match, destination)
match = self._FindDownload(line)
return line